# Secondary Sexual Characteristics in the Galerucinae (Sensu Stricto) (Coleoptera: Chrysomelidae)

Authors: M. S. Mohamedsaid; D. G. Furth
Journal: ISRN Zoology
 (2011)

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## Abstract

A list of 1298 species and 172 genera of Chrysomelidae from the subfamily Galerucinae (sensu stricto) with the males having at least one form of secondary sexual characteristic (SSC) is presented. The number of species amounts to 24% of the total Galerucinae presently known from all over the world—a very significant amount. The SSCs comprise various types of modified structures found on all parts of the body—head, thorax, and abdomen. They are not variable but species specific. Illustrations from selected 87 species that include 84 images and 15 line drawings showing various types of SSC are provided. The amazing array of SSCs from the Galerucinae offers a large and taxonomically diverse set of data that are not comparable with other subfamilies in the Chrysomelidae and may be useful in phylogenetic analysis of the family.


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## Body

## 1. Introduction

Galerucinae (sensu stricto) is the second largest subfamily within the Chrysomelidae (Coleoptera), represented by about 520 genera and between some 5000 species [1], 5500 species [2], and 6300 species [3] and  its most diverse distribution concentrated mainly in the tropical and subtropical regions.The classification of the Chrysomelidae proposed by Lawrence and Newton [4] lumped together the Galerucinae and Alticinae into a single subfamily Galerucinae (sensu lato).  Consequently, the Galerucinae (sensu stricto) was placed in the Tribe Galerucini and the Alticinae (sensu stricto) as the Tribe Alticini. Since then, some workers have continued to separate the two subfamilies as in the Seeno and Wilcox [5]. There has been support for Alticinae as a monophyletic group with metafemoral spring as the main character [6]. Likewise, Galerucinae has been considered paraphyletic with Alticinae as a subordinated clade [7]. On the other hand, Kim et al. [8] in their molecular and morphological-based phylogenetic studies showed that there is molecular data to support Alticinae as  a tribal ranking (Alticini) within the Galerucinae and neither  as  a separate subfamily. They suggested that more independent characters are needed. More recently, Gillespie et al. [1] claimed to have the most comprehensive phylogeny estimation and showed consistency with previous molecular phylogenetic reconstruction of Galerucinae, but at the same time agreed that there was a lack of taxon representation from the Old World. There is no doubt that more characteristics need to be utilised from a more complete range of taxa selected from the Old and New Worlds, that is,  better taxon sampling, including secondary sexual characteristics.In this study, we refer to a secondary sexual characteristic (SSC), defined by Mayr [9] as a modified structure of the male members of a species that distinguishes the two sexes of the species but does not function directly in reproduction. The modified structure from the male differs from homologous structures in the female. The SSC may provide an advantage during competition for mates, for example, the aquatic smooth newt, Triturus cristatus[Laurenti] (Amphibia: Salamandridae), is dimorphic with the male having a dorsal crest. Darwin thought that the function of the crest was to attract females, but it was a century later that it was demonstrated that females chose males exhibiting conspicuous dorsal crests [10]. Observational and experimental evidence suggest that feather ornaments of birds play an important role in female choice [11]. Eberhard [12, 13] referred to an SSC as the nongenitalic male contact structure, a product of an intersexual competition [14]. Besides agreeing that SSCs are the result of Darwinian selection, Jolivet [15] noted that they are also a manifestation of biodiversity.The SSCs are species specific; thus, they are important as diagnostic tools for identification. In the Chrysomelidae, particularly the subfamily Galerucinae, SSCs are found on various parts of the body, including head, thorax, and abdomen. The presence of these modified characteristics was discussed in some earlier works on the Galerucinae by Maulik [16, 17], who provided illustrations of modified antennae present in some members of the genus AgetoceraHope and modified clypeus in PalpoxenaBaly. According to Maulik [17], the antennae, clypeus, labrum, and maxillary palpi that have undergone extraordinary modifications possess a highly diagnostic value. Blake [18, 19] noted the modified characteristics, the excised metatibiae of the male, as important generic characters (Deinocladus Blake, Luperosoma Jacoby, andPorechontes Blake). Wilcox [20] noted that in some genera, for example, MalacorhinusJacoby, species in which the elytra are modified in the male are easily identified by that characteristic. Silfverberg [21] defined ProsmidiaWeise and NeolaetanaLaboissiere above all by their secondary sexual characteristics, the pronotum, and the basal area of the elytra being modified in the male.In constructing a phylogeny or a classification, a set of characters from morphological data are tabulated, representing common ancestor (plesiomorphy) and derived states (synapomorphy). The SSC is a derived characteristic. Phylogeny is a statement not only of relationships among taxa but also about the evolution of characters. There is little literature pertaining to the utilization of the SSCs in phylogenetic studies of Chrysomelidae; thus, these characteristics received scant attention. The earliest traceable work was that of Silfverberg [22] in a revision of the galerucine group Prosomidiites, only known from the Afrotropical Region. He employed the modified scutellar area of the elytra as the root for eight genera. Furthermore, according to Silfverberg, the modifications of the male pronotum and elytra are of a type not present in other Galerucinae and can, therefore, be considered apomorphic when found in the Prosomidiites. After more than thirty years, SSCs began to be considered in a phylogenetic analysis. Freund and Wagner [23] constructed a phylogenetic tree of 31 species, which employed 4 SSCs. Barroga and Mohamedsaid [24] in the construction of a phylogeny for genus AulacophoraChevrolat from Sundaland used 59 characteristics, including 13 SSCs. Recently, Stapel et al. [2] utilized the SSCs from the modified head, antennae, and elytra in their phylogenetic analysis on the Afrotropical MonoleptaChevrolat and related galerucine genera.The present paper has three objectives: (1) to compile all known of SSCs found in chrysomelid beetles of the subfamily Galerucinae (sensu stricto) from all over the world, (2) to provide some explanation on functions of the various modified structures, and (3) to highlight the myriad forms of SSCs in the Galerucinae and their taxonomic significance in the Chrysomelidae.


## 2. Materials and Methods

Information sources for SSCs from the subfamily Galerucinae (sensu stricto) were gathered in three ways. Unless otherwise stated, all reference to Galerucinae in this study means sensu  stricto. First, male specimens were examined physically for modified structures; second, data was extracted from descriptions and illustrations of modified structure in the literature; third, data was extracted through virtual examination of modified structure displayed on images of the males posted on websites of the Internet. Some of the figures included here were taken directly from websites and, therefore, their clarity and resolution may not be of high quality; however, we feel that they are adequate to illustrate the modifications discussed.  For the first phase of this study, the first author examined all the specimens in collection of the Centre for Insect Systematic, Universiti Kebangsaan Malaysia (UKM). Subsequently, three main websites were consulted in the Internet: GBIF Deutschland: http://www.biologie.uni-ulm.de/; MCZ, Harvard University: http://mcz-28168.oeb.harvard.edu/mcz/index.htm; Smithsonian Institution Library for the digital Biologia Centrali-Americana:  http://www.sil.si.edu/DigitalCollections/bca/explore.cfm.In this study, we decided to exclude modified last visible abdominal sternite (the apical sternite) and modified first segment of protarsi. The SSCs resulting from modifications of these characteristics are universal that are present in most males of the Chrysomelidae although the modified apical sternite is much more complex in Galerucinae (sensu stricto) than in other subfamilies.


## 3. Results

In the course of the present study, the generic names for a number of species are retained because they have not been revised or the revisions are only partially completed. The genusPlatyxanthaBaly was reduced by Reid [25] to a synonym of TaumaceraThunberg, but this synonymy applies only to species from the Oriental Region. Platyxanthafrom the African Region has not been revised, and in the present study, 28 species are listed with modified characteristics that possibly belong to another genus than Taumacera. The same is true with MonoleptaChevrolat, where its African fauna has been revised by Wagner [26], but the Oriental and Australasian faunas have not been revised, and we believe some of them could belong to another genus. Therefore, the name Monoleptais retained for 41 species listed here with modified characteristics despite the fact that true Monoleptaas redefined by Wagner [27] has no modified characteristics/SSCs. Another genus is NymphiusWeise recently revised by Bezděk [28], but for convenience, the following two species: Calomicrus(Nymphius) buettikeri(Medvedev) and C.(Nymphius) friedmani(Lopatin) with a modified abdomen are retained under Nymphius. This is because the abdomen of these two species has appendages, not a characteristic of the genus CalomicrusStephens. According to Bezděk, the two species should be placed into a separate new genus. Nevertheless, all these taxonomic changes that would have happened do not affect the total number of modified species from the subfamily Galerucinae and, of course, there would be changes in the total number of genera.As a result of this study, a list of 172 genera (AppendixA) and 1298 species (Appendix B) of the Galerucinae having SSCs is provided. These SSCs represent various types of modified structures found on all parts of the body head, thorax, and abdomen. Table 1 shows a distribution of various forms of modified structures of the SSCs found on the head, the thorax, and the abdomen. Table 2 shows distribution of the galerucine genera and species with modified head, thorax, and abdomens. Table 3 shows distribution of the galerucine genera and species with various types of modified antennae. Table 4 shows a list of 49 largest genera attributed to the main modified characteristics. Illustrations of 87 selected species, that include images of 84 species and line drawings of 15 species, are provided to show amazing and truly unusual SSCs of the Galerucinae. These SSCs are classified, tabulated, and provided with plausible explanations of their functions. However, it is beyond the scope of the present study to go into a detailed anatomy of the various modified structures.Table 1
Distribution of modified structures found on head, thorax and abdomen of the chrysomelid beetles subfamily Galerucinae (sensu stricto).
HeadAntennae with one, double, and triple segments, more than three segments modified, or covered with unusually long hairs. Vertex depressed or excavated, with surface smooth or with structures. Frontal tubercles ase very large. Clypeus is strongly convex, excavated, with surface smooth, or with structures. Labrum are extremely large or deformed. Maxillary palpi with the 3rd segment swollen. Eyes are large.ThoraxPronotumDisc bulged and excavated with structures. Posterior margin with process.ElytraElytra humpback. A pair of tubercles at base or at apex. A pair of cavities behind scutellum, in middle, at sides, or at apex. Humeri with rows of erect hairs.LegsFront legs: Femora emarginate. Tibiae thickened, curved, emarginated, excised, or notched. Middle legs: Tibiae curved, excised, or notched. Hind legs: Trochanters with a process, a spine, or blade-like structure. Femora enlarged and excavated. Tibiae broadened, excavated, or curved; apex of tibiae with a process. All tarsal claws bifid (simple or appendiculate in female).MetasternumMetasternum with posterior median lobe or covered with long hairs.AbdomenFirst abdominal sternite with an appendage, a tubercle, or a pair of appendages, or a projected covering the following four sternites; first and second sternites each with a pair of appendages; second visible sternite with an appendage; third sternite with one or a pair of long appendages; fourth sternite emarginated, with a triangular process, a pair of spines, or long appendages.Table 2
Distribution of galerucine genera and species with modified head, thorax, and abdomen.
Modified organsGenera (number of species)Head119 genera (756 species)Vertex10 genera (32 species)Aulacophora(12), Chthoneis(1), Coelomera(1), Lamprocopa(10),Malacorhinus(1), Monolepta(1), Monoleptocrania(1), Oroetes(2), Palpaenidea(2), Sarawakiola(1).Frontal tubercles1 genus (1 species)Hyphaenia(1).Clypeus24 genera (181 species)Acroxena(5), Afrocrania(5), Aulacophora(1), Azlania(4), Cerotoma(5), Chthoneis(1), Eccoptopsis(12), Eusattodera(1), Exosoma(1), Fleutiaxia(6), Gynandrobrotica(3), Hoplosaenidea(24), Hyphaenia(6), Hystiopsis(1), Kanahiiphaga(7), Macrima(9), Metrobrotica(1), Palpoxena(43), Porechontes(3), Pseudaenidea(2), Rachicephala(1), Sermyloides(31), Taumacera(6), Theopea(3).Labrum2 genera (10 species)Acroxena(1), Palpoxena(9).Maxillary palpi12 genera (51 species)Cyclotrypema(1), Aulacophora(5), Cneoranidea(5), Coelomera(1),Diabrotica(5), Gynandrobrotica(3),Hystiopsis(1),Luperodes(1), Palpaenidea(2),Palpoxena(25), Spilocephalus(1), Theopea(1).Eyes12 genera (35 species)Aulacophora(2), Cerophysa(1), Chapuisia(8),Chthoneis(1), Diabrotica (12),Haplosomoides(5), Hyphaenia(1), Liroetis(1),Luperodes(1),Platyxantha(1), Pseudoscelida (1),Rohaniella(1).Antennae119 genera (645 species)Segments modified109 genera (585 species)Acroxena(4),Afrocrania(5),Agetocera(23), Alphidia(1), Anisobrotica(2), Antsianaka(1), Apophylia(17), Arimetus(2),Arthrotus(1), Asbecesta(20), Aulacophora(53), Austrotella(2),Bangprella(1), Bonesia(2), Buckibrotica(1),  Cerophysa(35), Cerophysella(2), Cerotoma(3), Chapuisia(10), Chthoneis(3), Clitena(2), Cneorane(1), Coraia(2), Cornubrotica(2), Deinocladus (3), Dercetina(1), Diabrotica(21),Dircemella(1), Doryscus(1), Dreeus(1),Duvivieria(1), Eccoptopsis(12), Ectmesopus(3), Exosoma(2), Geinula(1), Halysacantha(1), Haplosomoides(3), Hoplosaenidea(7), Huillania(3), Hylaspoides(1), Hymnesia(1), Hyphaenia(4), Japonitata(3), Kinabalua(2), Laetana(1), Laetiacantha(10), Leptoxena(1), Lesnella(1), Liroetiella(1), Luperodes(2), Luperosoma (9), Malacorhinus(5),Megalognatha(59), Metacoryna(5), Metopoedema(1),Metrobrotica(2), Microlepta(1),Miltina(1), Neolaetana(5), Niasia(3), Nirina(3), Nirinoides(3), Oidomorpha(1),Oorlogia(1), Ornithonagthus(1), Oroetes(2),Orthoxia(1), Palpaenidea(1),Palpoxena(6), Parabrotica(1), Paraplotes(3), Parabescesta(6), Paratriarius(2), Periclitena(2), Phyllecthris(3), Phyllobrotica(1), Phyllobroticella(7), Pimentelia(1), Platybrotica(1), Platyxantha(19), Porechontes(2),Pseudorupilia(2), Pseudoshaira(1),Pseudoscelida(2),Rohaniella(1), Ruwenzoria(1), Samoria(7),Sarawakiola(1), Schematiza(5), Sermyloides(26), Sessilia(1), Shungwayana(1),Sikkimia(4), Simopsis(1), Spilocephalus(3), Spilonotella(1), Stenoplatys(2), Synetocephalus(1), Taenala(2), Taphinella(1), Taumacera(41), Taumaceroides(1), Theopea(5), Therphis(1), Trichomimastra(1), Vitruvia(1), Xenarthra(6), Xenoda(23), Zinjotella(1).With 10 segments2 genera (5 species)Oroetes(2), Phyllecthris(3)With    long hairs19 genera (55 species)Acroxena(1), Aelianus(1), Apophylia(1), Arthrotus(1),Aulacophora(2), Cerophysa(1), Cerophysella(1), Chthoneis(1),Dimalianella(2), Eleona(1),Haplosomoides(1), Hyphaenia(21), Leptaulaca(5), Mahutia(1), Mimastra(1), Platyxantha(7), Pseudoscelida(2), Sinoluperoides(1),Stenellina(4).Thorax37 genera (379 species)Pronotum10 genera (38 species)With tubercles4 genera (17 species)Bacteriaspis(2), Cannonia(4), Paracanthina(2), Prosmidia(9).With cavities5 genera (19 species)Jacobya(5), Laetiacantha(9), Neolaetana(3), Oroetes(1), Paleosepharia(1).Posterior process5 genera (22 species)Cannonia(4), Laetiacantha(6), Paleosepharia(1), Prosmidia(9), Taenala(2).Scutellum tongue-shapedProsmidia(3).Elytra30 genera (304 species)With tubercles10 genera (119 species)Bacteriaspis(2), Cannonia(2), Diacantha(81), Elyces(1), Halysacantha(1), Laetiacantha(10), Lesnella(1), Paracanthina(2), Prosmidia(18), Sonchia(1).With cavities19 genera (180 species)Afroatrachya(1), Afrocrania(10), Androlyperus(6), Atrachya(5), Austrotella(2), Candezea(8), Cerophysella(2), Erythrobapta(1), Lomirana(1), Malacorhinus(8), Monolepta(30), Neolaetana(5), Paleosepharia(44), Paratriarius(8), Paridea(15), Phyllobroticella(7), Pseudocophora(25), Pseudocrania(2), Strobiderus(1).Humeral hairsAulacophora(5).Metasternum4 genera (60 species)Apophylia(12), Cneoranidea(1), Kinabalua(2), Taumacera(45).Legs88 genera (401 species)Hind trochanterCoeligetes(1), Liroetis(1), Monolepta(1).Front femoraLygistus(1),Mahutia(1), Taumaceroides(1).Middle femoraCornibrotica(1),Mahutia(1).Hind femoraMahutia(1), Leptoxena(1), Apophylia(3).Front tibiaeCornubrotica(1),Cyclotrypema(1), Eccoptopsis(1), Eleona(1), Hoplosaenidea(1),Hystiopsis(3), Leptaulaca(1), Metrobrotica (1), Mombasa(3), Parabrotica(1),Platymorpha(2), Platyxantha(1),Simopsis(1),Stenoplatys(1), Synetocephalus(1),  Luperosoma(9),Taumacera(2),Taumaceroides(1).Middle tibiaeCoraia(2),Cornubrotica(1),Deinocladus(3),Dreeus(1),Ephaenidea(1),Haplosomoides(1),Momaea(1), Oroetes(1),Parabrotica(1),Phyllecthris(3),Platymorpha(1), Porechontes(3),Simopsis(1),Synetocephalus(1), Taumacera(2), Trichobrotica (9).Hind tibiaeApophylia(2),Cerophysa(1),Duvivieria(1),Haplosomoides(1),Hoplasoma(1),Hoplosaenidea(3), Lilophaea(1), Luperodes(1), Platyxantha(2),Scelida(1),Scelidacne(1),Scelolyperus(15),Synetocephalus(1), Taumacera(11).Tarsal claws bifid2 genera (153 species)Apophylia(148), Erynephala(5)Abdomen18 genera (66 species)Anatela(1), Androlyperus(1), Apophylia(6), Cneoranidea(1), Ceoligetes(2), Euliroetis(5), Haplosomoides(13), Hemigascelis(1), Hoplasoma(13), Inbioluperus(1), Liroetis(2), Luperogala(2), Mimastra(2), Nymphius(9), Phyllobrotica (4),Pseudoluperus(1), Scelida(1), Scelidacne(1).Table 3
Distribution of galerucine genera and species with various types of modified antennal segments.
Modified segmentsGenera (number of species)Single41 genera and 156 species1st9 genera and 21 species:Antsianaka(1),Aulacophora(8), Doryscus(1), Hoplosaenidea(4),Malacorhinus(2), Metopoedema(1), Palpoxena(1), Paraplotes(1),  Sarawakiola(1).3rd9 genera and 40 species:Arthrotus(1),Aulacophora(1), Halysacantha(1), Hylaspoides(1), Metrobrotica(1), Microlepta(1),Palpoxena(1),Sermyloides(26),Taumacera(16).4th7 genera 12 species:Afrocrania(4), Cerophysa(2),Geinula(1), Hoplosaenidea(1),Hyphaenia(1), Luperodes(2),Palpaenidea(1).5th1 genus and 4 species:Apophylia(4).7th6 genera 24 species:Bangprella(1), Dercetina(1), Duvivieria(1),Megalognatha(19), Oidomorpha(1),Palpoxena(1), Ruwenzoria(1).8th8 genera and 23 species:Clitena(1), Hymnesia(1), Apophylia(1), Cerophysa(15), Dircemella(1), Metacoryna(1), Periclitena(2), Pseudoscelida(1).9th5 genera and 8 species:Agetocera(4),Cerophysa(1), Metacoryna(1), Periclitena(1), Porechontes(1).10th1 genus and 2 species:Ectmesopus(2).11th4 genera and 12 species:Aulacophora(7), Luperosoma(3), Paraplotes(1), Phyllobrotica(1).Double27 genera and 106 species1st  and 3rd2 genera and 3 species:Acroxena(2),Taumacera(1).3rd  and 4th12 genera and 36 species:Apophylia(1), Cerophysa(2),Cerotoma(3),Eccoptopsis(12), Hoplosaenidea(2), Laetana(1), Liroetiella(1),  Malacorhinus(1), Metrobrotica (1), Oroetes(2), Phyllobroticella(7),Taumacera(3).3rd and 8th1 genus and 1 species:Taumacera(2).4th  and 5th1 genus and 1 species:Afrocrania(1).5th  and 6th2 genera and 2 species:Taumacera(1), Taumaceroides(1).6th  and 7th3 genera and 11 species:Cerophysa(6), Megalognatha(4), Taumacera(1).7th  and 8th2 genera and 6 species:Kinabalua(2), Megalognatha(4).7th  and 9th1 genus and 1 species:Buckibrotica(1).8th  and 9th7 genera and 29 species:Agetocera(19), Cornubrotica(2),  Hyphaenia(1), Megalognatha(2), Metacoryna(3), Nirina(1), Taumacera(1).9th  and 10th4 genera and 8 species:Hyphaenia(1),Luperosoma(1), Stenoplatys(1),Taumacera(5).9th  and 11th1 genus and 1 species:Dreeus(1).10th and 11th3 genera and 6 species:Platyxantha(1), Sikkimia(4), Taumacera(1).Triple21 genera and 97 species3rd, 4th,  and 5th3 genera and 36 species:Acroxena(1),Aulacophora(34), Cerophysa(1).3rd, 6th, and 7th1 genus and 1 species:Taumacera(1).3rd, 8th, and 9th2 genera and 3 species:Porechontes(1), Taumacera(2).4th, 5th,  and 6th2 genera and 3 species:Cerophysa(2), Chthoneis(1).5th, 6th,  and 7th2 genera and 2 species:Paratriarius(1), Platyxantha (1).6th, 7th,  and 8th3 genera and 16 species:Asbecesta(1),Cerophysa(2),Megalognatha(13).6th, 9th, and 10th1 genus and 1 species:Taumacera(1).7th, 8th,  and 9th3 genera and 13 species:Asbecesta(4),Megalognatha(8), Paratriarius(1).8th, 9th,  and 10th4 genera and 4 species:Asbecesta(1),Eccoptopsis(1),Hoplasoma(1), Trichomimastra(1).9th, 10th,  and 11th9 genera and 20 species:Anisobrotica(2), Apophylia(5), Cneorane(1), Japonitata(1),Leptoxena(1),Luperosoma(3), Stenoplatys(1),Taumacera(5),Vitruvia(1).More than three segments modified71 genera and 232 speciesAcroxena(1), Agetocera(1), Apophylia(6),Arimetus(2),Arthrotus(1),Asbecesta(14), Aulacophora(5), Austrotella(2),Bonesia(2), Buckbrotica(1),Cerophysa(6), Cerophysella(1), Chapuisia(10),Chthoneis(3), Clitena(1), Cneorane(1), Coraia(2),Deinocladus(3), Diabrotica(21),Ectmesopus(1), Exosoma(2), Haplosomoides (3), Huillania(3), Hyphaenia(1), Jacobya(1), Japonitata(2), Laetana(1), Laetiacantha(10), Lesnella(1), Luperosoma(2), Malacorhinus(2),  Megalognatha(4), Miltina(1), Neolaetana(5), Niasia(3), Nirina(2),Nirinoides(3),Oorlogia(1),Ornithognathus (1),Orthoxia(1), Palpoxena(2),Parabrotica(1), Paraplotes(2), Parasbecesta(6), Paratriarius(2),Pimentelia(1), Platybrotica(1),  Platyxantha(16), Pseudorupilia(2),Pseudoscelida(1),Pseudoshaira(1),Rohaniella(1), Ruwenzoria(1),Samoria(7),Schematiza(5),Sessilia(1), Shungwayana(1),Simopsis(1), Spilocephalus(2), Spilonotella(1),Stenoplatys(1),Synetocephalus(1),Taenala(1),Taphinella(1), Taumacera(3), Theopea(5), Therpis(1),Trichomimastra(1),Xenarthra(6), Xenoda(23).Table 4
List of 49 largest genera with common modified organs.
GeneraNo. of speciesCommon modified organs(1)Apophylia148Tarsal claws bifid(2)Diacantha81Elytra tuberculate(3)Megalognatha59Antennal segments modified(4)Aulacophora54Antennal segments modified(5)Taumacera45Metasternum with posterior process(6)Paleosepharia44Elytra excavated(7)Palpoxena41Head excavated(8)Cerophysa33Antennal segments modified(9)Monolepta31Elytra excavated(10)Sermyloides31Head excavated(11)Pseudocophora25Elytra excavated(12)Hoplosaenidea24Head excavated(13)Hyphaenia24Antennae with long hairs(14)Xenoda23Antennal segments modified(15)Agetocera22Antennal segments modified(16)Diabrotica21Antennal segments modified(17)Asbecesta20Antennal segments modified(18)Prosmidia18Elytra tuberculate(19)Platyxantha17Antennal segments modified(20)Paridea15Elytra excavated(21)Hoplasoma13Abdomen with appendages(22)Diabrotica13Eyes large(23)Eccoptopsis12Antennal segments modified(24)Afrocandezea11Elytra excavated(25)Haplosomoides11Abdomen with appendages(26)Lamprocopa10Head excavated(27)Laetiacantha10Elytra tuberculate(28)Afrocrania10Elytra excavated(29)Scelolyperus10Hind tibiae curved(30)Macrima9Head excavated(31)Nymphius9Abdomen with appendages(32)Luperosoma9Middle tibiae notched(33)Trichobrotica9Middle tibiae notched(34)Malacorhinus8Elytra excavated(35)Candezea8Elytra excavated(36)Chapuisia8Eyes large(37)Kanahiiphaga7Head excavated(38)Phyllobroticella7Antennal segments modified(39)Samoria7Antennal segments modified(40)Fleutiauxia6Head excavated(41)Parabecesta6Antennal segments modified(42)Metacoryna5Antennal segments modified(43)Schematiza5Antennal segments modified(44)Theopea5Antennal segments modified(45)Cneoranidea5Maxillary palpi large(46)Atrachya5Elytra excavated(47)Neolaetana5Elytra excavated(48)Euliroetis5Abdomen with appendages(49)Jacobya5Pronotum excavatedEvery part of the body, including the head, thorax, and abdomen, is affected with some forms of modifications (Tables1, 2, and 3). Table 1 shows various modified structures present on the head, thorax, and abdomen. On the head, almost every aspect has a structure that has undergone modification, including vertex, frontal tubercles, clypeus, labrum, maxillary palpi, eye, and antenna. Table 2 shows distribution of galerucine genera and species with the modified structures. Modifications of head structures are found in 756 species and 119 genera. These modified structures can be described as simple to complex. The simple modified vertex has a smoothly bulged surface, or smoothly, strongly depressed surface (Monolepta flavicollis(Gyllenhal) (Figure 1)). The complex modified vertex has a depressed or excavated area with ridges or other structures (Aulacophora frontalisBaly (Figure 2)).Figure 1
Modified head:Monolepta flavicollis(Gyllenhal).Figure 2
Modified head:Aulacophora frontalisBaly.The clypeus is located anterior to the frontal tubercles. The modified clypeus is found in 181 species and 24 genera (Table2). The genus PalpoxenaBaly has the highest number of modified clypeus, represented by 43 species. A simple modified clypeus has its surface transversely, deeply depressed and without structures (Cerotoma atrofasciataJacoby (Figure 3)). A complex one has some forms of structures, such as ridges, projections, and hairs. In Aulacophora cornutaBaly (Figures 4(a) and 4(b)), the clypeus is deeply excavated anteriorly and with a process at sides. In an extreme case, the modified clypeus is deformed or disfigured (Palpoxena divisa(Jacoby) (Figure 5), P. sumatrensis(Jacoby) (Figure 6), and Eccoptopsis denticornis(Jacoby) (Figures 7(a) and 7(b))). Mouthparts affected with modifications are labrum and maxillary palpi. Modified labrum in form of extremely large size is found in two genera, AcroxenaBaly and PalpoxenaBaly. The labrum is either transverse (P. barbata(Baly) (Figures 8(a) and 8(b))) or triangularly shaped (P. coeruleipennis (Baly) (Figure 9) and P. variabilis (Jacoby) (Figure 10)). Maxillary palpi with modification are quite common, and they are found in 51 species and 12 genera. In some species the modification is very extreme and the usually cylindrical-shaped of the palpi is deformed (Palpoxena laeta(Baly) (Figure 11)). Males with large size of eyes are found in 35 species and 12 genera (Table 2).Figure 3
Modified head:Cerotoma atrofasciataJacoby.Modified head:Aulacophora cornutaBaly.
(a)(b)Figure 5
Modified head:Palpoxena divisa(Jacoby).Figure 6
Modified head:Palpoxena sumatrensis(Jacoby).Modified head:Eccoptopsis denticornis(Jacoby).
(a)(b)Modified labrum:Palpoxena barbata(Baly).
(a)(b)Modified labrum:Palpoxena coeruleipennis(Baly).
(a)(b)Figure 10
Modified labrum:Palpoxena variabilis(Jacoby).Figure 11
Modified maxillary palpi ofPalpoxena laeta(Baly).The modified antennae are the most widely distributed, found in 645 species and 119 genera (Table2). The number of species with modified antenna amounts to 50% of the total modified Galerucinae. The genus MegalognathaBaly has the highest number with modified antenna, represented by 59 species. Generally, all males and females have 11 antennal segments. However, in the following two genera, OroetesJacoby and PhyllecthrisDejean, the male has the antenna with 10 segments compared with 11 in females. Every antennal segment, from the first to the eleventh, is affected by some form of modification. A simple modification is an enlargement of a segment, without any cavity, structure, or gland. A complex one affects more than one segment. Besides, some of the modified segments appear totally different from normal feature, being distorted or deformed.Table3 shows distribution of galerucine genera and species with various types of modified antenna. There are examples of sets of single, double, triple, and more than three modified segments. Antennal segment 2 is rarely modified but always reduced to a minute size if segment 3 is greatly modified, as in Taumaceraspp. However, in Aulacophora diversaBaly and A. dulitensisBarroga and Mohamedsaid, segment 2 is enlarged and dilated at apex and modified together with segments 3–7. The same is with segment 6 that is never singularly modified but always combined with other segments, such as in the double modified segments 5 and 6 (Taumaceroides sinicusLopatin) and segments 6 and 7 (Taumacera variceps(Laboissiere); and in the triple modified segments 5, 6, and 7 (Paratriarius dorsatus(Say), and segments 6, 7, and 8 (Megalognatha rolettiLaboissiere (Figure 34)).There are 156 species in 41 genera having a single modified antennal segment. Segment 3 is the most affected and found in 40 species and 9 genera. The genusSermyloidesJacoby has the highest number with the 3rd segment modified, represented by 26 species. The following are some examples of species with the single modified antenna that affect segment 1 (A. cornuta(Figure 4) andSarawakiola ajaibMohamedsaid (Figure 12)), segment 3 (Taumacera sucki(Weise) (Figure 13)), segment 4 (Afrocrania kaethae Middelhauve and Wagner (Figure 14) and A. latifrons(Weise)), segment 5 (Apophylia incisitarsis(Laboissiere) (Figure 15)), segment 7 (Duvivieria apicitarsisWeise (Figure 16) and Megalognatha grouvellei(Weise) (Figure 17)),  segment 8 (Cerophysa flava Baly (Figure 18) and Cerophysa gestroiJacoby (Figure 19)), segment 9 (Metacoryna guatemalensisJacoby (Figure 20) and Agetocera silva(Bezděk) (Figure 21)), segment 10 (Ectmesopus darlingtoniBlake, (Figure 22)) and segment 11 (Aulacophora luteicornis(Fabricius) (Figure 23)).Figure 12
Modified antennae:Sarawakiola ajaibMohamedsaid.Figure 13
Modified antennae:Taumacera sucki(Weise).Figure 14
Modified antennae:Afrocrania kaethaeMiddelhauve and Wagner.Figure 15
Modified antennae:Apophylia incisitarsis(Laboissiere).Figure 16
Modified antennae:Duviviera apicitarsisWeise.Figure 17
Modified antennae:Megalognatha grouvelleiWeise.Figure 18
Modified antennae:Cerophysa flavaBaly.Figure 19
Modified antennae:Cerophya gestroiJacoby.Figure 20
Modified antennae:Metacoryna guatemalensisJacoby.Figure 21
Modified antennae:Agetocera silvaBezděk.Figure 22
Modified antennae:Ectmesopus darlingtoniBlake.Figure 23
Modified antennae:Aulacophora luteicornis(Fabricius).There are 106 species in 27 genera having a set of double modified antennal segments with segments 3 and 4 the most affected, which is found in 36 species and 12 genera. But the genusAgetoceraHope with the double modifications of segments 8 and 9 has the highest number, represented by 19 species.  Examples of species with double modifications of segments 1 and 3 (Taumacera khalednordini Mohamedsaid (Figure 24)), segments 3 and 4 (Hoplosaenidea aerosa(Laboissiere) (Figure 25) and Cerotoma ruficornis(Olivier) (Figure 26)), segments 4 and 5 (Afrocrania foveolata(Karsch)), segments 5 and 6 (Taumaceroides sinicus), segments 6 and 7 (Cerophysa sumatrensis(Jacoby) and Taumacera variceps); segments 7 and 8 (Kinabalua musaamani Mohamedsaid (Figures 27(a) and 27(b))),  segments 8 and 9 (Taumacera occipitalis(Laboissiere) (Figure 28), Metacoryna fulvipes Jacoby (Figure 29) and M. jacobyi Bowditch (Figure 30)); segments 9 and 10 (Agetocera nigripennis Laboissiere (Figure 31)). Apparently in Metacoryna jacobyi the modified segments are fused together and appear as one.Figure 24
Modified antennae:Taumacera khalednordiniMohamedsaid.Figure 25
Modified antennae:Hoplosaenidea aerosa(Laboissiere).Figure 26
Modified antennae:Cerotoma ruficornis(Olivier).Modified antennae:Kinabalua musaamaniMohamedsaid.
(a)(b)Figure 28
Modified antennae:Taumacera occipitalis(Laboissiere).Figure 29
Modified antennae:Metacoryna fulvipesJacoby.Figure 30
Modified antennae:Metacoryna jacobyi Bowditch.Figure 31
Modified antennae:Agetocera nigripennis Laboissiere.There are 97 species in 21 genera having a set of triple modified antennal segments with a combination of segments 3, 4, and 5 the most commonly affected and found in 36 species and 3 genera.  The genusAulacophorahas the highest number of triple modifications, represented by 34 species.  Examples of triple modifications are segments 3, 4 and 5 (Aulacophora laevifrons Baly (Figure 32) and A. martia Weise (Figure 33)), segments 5, 6, and 7 (Paratriarius dorsatus(Say)), segments 6, 7, and 8 (Megalognatha rolleti Laboissiere (Figure 34)), segments 7, 8, and 9 (Paratriarius neocrassicornis(Bowditch)) and segments 9, 10, and 11 (Vitruvia clavicornisWeise).Figure 32
Modified antennae:Aulacophora laevifrons Baly.Figure 33
Modified antennae:Aulacophora martia Weise.Figure 34
Modified antennae:Megalognatha rolleti Laboissiere.The modified antenna with more than three segments is the most common and widely distributed, found in 232 species and 71 genera. The genusXenodaBaly has the highest number with more than three segments modified and represented by 23 species. The affected segments are either a combination of three or more basal, apical, or a combination of almost all the antennal segments. Examples are (Malacorhinus antennatusJacoby (Figure 35), Megalognatha variicornis(Weise) (Figure 36), Exosoma deformicornis(Queddenfledt) (Figure 37) and Megalognatha femoralisLaboissiere (Figure 38)). However, in the genus Xenoda (subgenus Xenoda), all modified segments 3 to 8 are united into more or less one piece (Xenoda pallidaJacoby (Figure 39) and X. ovalisMohamedsaid (Figure 40)).  This union of segments is also found in other species, but it affects two segments, the 8th and 9th, as in Metacoryna jacobyi(Figure 30). Besides affecting the shape of antennal segments, the modified antenna is also the one with the presence of long hairs. There are 55 species in 19 genera having antenna covered with long hairs.Figure 35
Modified antennae:Malacorhinus antennatus Jacoby.Figure 36
Modified antennae:Megalognatha variicornis Weise.Figure 37
Modified antennae:Exosoma deformicornis(Queddenfledt).Figure 38
Modified antennae:Megalognatha femoralisLaboissiere.Figure 39
Modified antennae:Xenoda pallidJacoby.Figure 40
Modified antennae:Xenoda ovalis Mohamedsaid.In thorax, these modified structures are found on pronotum, scutellum, elytra, legs, and the ventrite of the third thoracical segment (Table2). The modified pronotum is the least represented, found in 38 species and 10 genera. The pronotum has either the disc bulged or excavated (Jacobya cavicollis(Fairmaire) (Figure 41)), or the middle of posterior margin bearing a short process or knob (Cannonia meridionalis(Weise) (Figure 42)). In an isolated case, scutellum for three species of Prosmidiais transformed into tongue-liked shape (P. suahelorumWeise (Figure 43)). In addition, these species also have both pronotum excavated and elytra with a pair of tubercles.Modified pronotum:Jacobya cavicollis(Faimaire).
(a)(b)Figure 42
Modified pronotum:Cannonia meridionalis(Weise).Figure 43
Modified pronotum:Prosmidia suahelorumWeise.Modified elytra are the most widely distributed and found in 304 species and 30 genera (Table2). The number of species with modified elytra amounts to 24% of the total modified Galerucinae. There are two types of modified elytra, one is with the presence of tubercles and the other with cavities. The modified structures are located either at base, posterior to scutellum or between scutellum and humeri laterally, or at the apex of the elytra. In Elyces quadrimaculataJacoby the humerus is strongly tuberculate. A pair of tubercles is located either at the base of elytra (Laetiacantha distincta(Gahan) (Figure 44) and Laetiacantha ruficollisLaboissiere (Figure 45)), or at the apex of elytra, found in 81 species of the genus DiacanthaChevrolat. The tubercles have various sizes and shapes, such as rounded (Diacantha senegalensis(Laboissiere) (Figure 46)), pointed (D. insignipennisThomson (Figure 47) and D. varians Weise (Figure 48)), bifurcate (D. cupripennis(Laboissiere) (Figure 49)), semicircular-shaped (D. bituberculata(Fabricius) (Figure 50)), and elongate and parallel to the suture (D. dimidiata(Laboissiere) (Figure 51)). In an extreme case the tubercle forms a long lateral carina, extending from the humeri to apex (Candezea bicostata(Weise) (Figure 52)).Figure 44
Modified elytra:Laetiacantha distincta(Gahan).Figure 45
Modified elytra:Laetiacantha ruficollisLaboissiere.Figure 46
Modified elytra:Diacantha senegalensis(Laboissiere).Figure 47
Modified elytra:Diacantha insignipennisThomson.Figure 48
Modified elytra:Diacantha varians Weise.Figure 49
Modified elytra:Diacantha cupripennis(Laboissiere).Figure 50
Modified elytra:Diacantha bituberculata(Fabricius).Figure 51
Modified elytra:Diacantha dimidiata(Laboissiere).Figure 52
Modified elytra:Candezea bicostata(Weise).Opposite to the formation of a tubercle, the elytra are excavated. There are various sizes and shapes of the cavities, as well as their depth. The cavities are located on various parts of the disc, posterior to the scutellum, in the middle, at sides, or at apex of the elytra. The most common are located at posterior of the scutellum. Simple excavated elytra have traces of a cavity, or with shallow depression (Afrocrania ubatubaeMiddelhauve and Wagner (Figure 53)), with a straight groove (Paleosepharia jambuicaMohamedsaid (Figure 54)), an outward oblique at the posterior (P. zakriiMohamedsaid (Figure 55), P. lawaMohamedsaid (Figure 56) and P. legendaMohamedsaid (Figure 57)), or a spindle-shaped cavity (P. tenasserimensis(Maulik) (Figure 58)). In Monolepta kerangas(Mohamedsaid) (Figure 59), the cavity is located in the middle and the elytra humpbacked view from side. A few species have the cavity located at apex of elytra (Paratriarius alternans(Weise); Strobiderus excavatusJacoby). In other species, the cavity is funnel shaped and located at the base between scutellum and humerus (Neolaetana alternans(Silfverberg)). Pseudocrania basalisJacoby (Figure 60) has the broadest excavated elytra.  In addition, in the following two genera: MalacorhinusJacoby andAndrolyperusCrotch, the cavities are located at the sides. In the former, the cavities are located in the middle and the latter near the apex of the elytra. Examples are M. decempunctatusJacoby (Figures 61(a) and 61(b)), M. foveipennisJacoby (Figure 62), M. tripunctatusJacoby (Figure 63) and A. nataliaeClark (Figure 64). Another type of modified elytra is with the presence of rows of erect hairs on shoulders, which is found in five species of Aulacophora.Figure 53
Modified elytra:Afrocrania ubatubaeMiddelhauve and Wagner.Figure 54
Modified elytra:Paleosepharia jambuicaMohamedsaid.Figure 55
Modified elytra:Paleosepharia zakriiMohamedsaid.Figure 56
Modified elytra:Paleosepharia lawaMohamedsaid.Figure 57
Modified elytra:Paleosepharia legendaMohamedsaid.Figure 58
Modified elytra:Paleosepharia tenasserimensis(Maulik).Figure 59
Modified elytra:Monolepta kerangasMohamedsaid.Figure 60
Modified elytra:Pseudocrania basalisJacoby.Modified elytra:Malacorhinus decempunctatusJacoby.
(a)(b)Figure 62
Modified elytra:Malacorhinus foveipennis(Jacoby).Figure 63
Modified elytra:Malacorhinus tripunctatus(Jacoby).Figure 64
Modified elytra:Androlyperus nataliaeClark.The modified leg includes modifications on any part of it, which include trochanter, femur, tibia, tarsus, and claws. There are 401 species in 88 genera with modified legs (Table2). The number of species with modified leg amounts to 31% of the total modified Galerucinae. The affected part of the leg is either enlarged, emarginated, excised, with a process, or spine, or having a different set of tarsal claws. The male has bifid tarsal claws in contrast to the female with either appendiculate or simple claws. The genus ApophyliaThomson, represented by 148 species, has a characteristic of bifid tarsal claws differing from females that have appendiculate claws. Another genus with the male having bifid tarsal claws is ErynephalaBlake, represented by 5 species.The modified tibia is the widely distributed modification of the leg, represented by 103 species and 39 genera. Examples of part of the modified leg are metatrochanter with a long spine inCoeligetes borneensisMohamedsaid (Figure 65); protibia enlarged in Mombasa magna(Weise) (Figure 66) and Cerotoma dilatipesJacoby (Figure 67); protibia emarginate in Taumacera tibialisMohamedsaid (Figure 68); mesotibia emarginated in Dreeus distinctus(Shute) and Taumacera midtibialisMohamedsaid (Figure 69); metatibia curved and with a tooth in the middle in Scelolyperus tejonicusCrotch (Figure 70). In the two rare species, Sastroides tarsalisMohamedsaid and Momaea distinctaMohamedsaid (Figures 71(a) and 71(b)), two parts of the same leg are modified, the mesotibia and mesotarsus, with the former excavated and covered with a series of pegs and the latter has a long process. A modified first segment of protarsus is common in the Chrysomelidae, but in some Galerucinae, it is strongly dilated as in Taumacera yamamotoi(Mohamedsaid) (Figure 72).Figure 65
Modified legs:Coeligetes borneensis Mohamedsaid.Figure 66
Modified legs:Mombasa magna(Weise).Figure 67
Modified legs:Cerotoma dilatipesJacoby.Figure 68
Modified legs:Taumacera tibialisMohamedsaid.Figure 69
Modified legs:Taumacera midtibialisMohamedsaid.Figure 70
Modified legs:Scelolyperus tejonicusCrotch.Modified legs:Momaea distinctaMohamedsaid.
(a)(b)Figure 72
Modified legs:Taumacera yamamotoi(Mohamedsaid).The thorax also has the modified structures on the venter of its third segment, known as the metasternum, and this is found in 60 species and 4 genera. The modified metasternum is present in tubercle (Apophylia nobilitataGerstaecker (Figure 73)), an elongated lobe (Kinabalua musaamaniMohamedsaid (Figure 74)) or a laminated lobe (Taumacera midtibialis(Figure 75)).  Besides, in Cneoranidea hirta(Yang), the metasternum is covered with long hairs.Figure 73
Modified ventrite of thorax:Apophylia nobilitataGerstaecker.Figure 74
Modified ventrite of thorax:Kinabalua musaamaniMohamedsaid.Figure 75
Modified ventrite of thorax:Taumacera midtibialisMohamedsaid.The abdomen has the sternite with modified structures in the present appendages, tubercles, and hairs. There are 66 species in 18 genera with modified abdomen (Table2). The number of species with modified abdomen amounts to 5% of the total modified Galerucinae. The genus HoplasomaJacoby has the highest number with modified abdomen, represented by 13 species. The modified abdominal sternite are either densely covered with long hairs (Hemygascelis longicollisJacoby (Figure 76)), or bearing one piece (Haplosomoides chinmatraMaulik (Figure 77)), a pair (Coeligetes submetallicaJacoby (Figure 78) and Hoplasoma unicolor(Illiger) (Figure 79)), or two pairs of appendages (H. apicaleJacoby (Figure 80), Androlyperus fulvusCrotch (Figure 81) and Scelida flaviceps(Horn) (Figure 82)). Also a complex abdominal appendage is found in species of NymphiusWeise (N. ensifer(Guillebeau) (Figure 83), N. forcipifer(Weise) (Figure 84), N. gianassoiBezděk (Figure 85), N. lydius(Weise) (Figure 86), N. ogloblini(Bogachev) (Figure 87), N. pravei(Jacobson) (Figure 88), and N. stylifer(Weise) (Figure 89)).Figure 76
Modified abdomen:Hemygascelis  longicollis Jacoby.Figure 77
Modified abdomen:Haplosomoides chinmatraMaulik.Figure 78
Modified abdomen:Coeligetes submetallicaJacoby.Figure 79
Modified abdomen:Hoplasoma unicolor(Illiger).Figure 80
Modified abdomen:Hoplasoma apicaleJacoby.Figure 81
Modified abdomen:Androlyperus fulvus(Crotch).Figure 82
Modified abdomen:Scelida flaviceps(Horn).Figure 83
Modified abdomen:Nymphius ensifer(Guillebeau).Figure 84
Modified abdomen:Nymphius forcipifer(Weise).Figure 85
Modified abdomen:Nymphius gianassoiBezděk.Figure 86
Modified abdomen:Nymphius lydius(Weise).Figure 87
Modified abdomen:Nymphius ogloblini(Bogachev).Figure 88
Modified abdomen:Nymphius pravei(Jacobson).Figure 89
Modified abdomen:Nymphius stylifer(Weise).Table4 presents a list of 49 largest genera represented by at least 5 species. These genera represent 1007 species or 74% of the total 1298 species presently listed. The genus Apophyliahas the highest number of species (148) with modified structures followed by Diacantha(81), Megalognatha(59), Aulacophora(54), and Taumacera(45). However, the most common form of SCC is the modified antennae, followed by the modified elytra and the modified head.Worldwide distribution of modified Galerucinae both from the Old and New Worlds has the former represented by 88% of the total modified species of the subfamily. The Luperini is the major tribe and represented by 84% of the total modified species in the Galerucinae. The Old World Luperini has the highest representation of SCCs with 87% of the total modified Luperini. The Galerucini from the Old World has the highest representation with 90% of the total modified from the tribe.


## 4. Discussion

A total of 1298 species and 172 genera of the Galerucinae (sensu stricto) with SSCs are recorded; a huge number.  The modified species represent about 24% of the total number of the Galerucinae, based on an estimate of 5500 species [2]. However, we believe that there are many more species with SSCs that either we were not aware of or were not available for our examination. Our observations were mainly based on original descriptions and illustrations and images of types that are posted on websites of various institutions. However, there are many species that were described based on female specimens and/or are the only images posted on websites. There is a high possibility that males belonging to a species that was described based on a female have modified characteristics, but there are no images or subsequent descriptions of males of these species.  In certain species, we know that some congeneric species described based on the female have males with modified characteristics. We also know that not all males of congeneric species have SSCs; therefore, we cannot make an assumption that a particular species described based on female has male with  modified characteristics without examining  the specimen, and such a species is discounted in the present study. Despite these deficiencies, we believe that our compilation of species of the Galerucinae with SSCs is representative for the subfamily. We believe that this study has covered more than 80% of all known species of the Galerucinae from around the world and recorded well the presence of the secondary sexual characteristics.Among the three body parts (head, thorax, and abdomen), the head with various modified structures (vertex, frontal tubercles, clypeus, labrum, maxillary palpi, and antennae) has the widest representation in the Galerucinae, found in 756 species and 119 genera. The thorax with modified pronotum, elytra, third thoracic sternite, and legs is found in 379 species under 37genera. In the modified thorax, the elytra have the highest representation with 304 species, followed by modified first foretarsal segments with 158 species. The ventrites with the modified third thoracic sternite and abdominal sternites combined are found in 126 species of 20 genera. In the modified head, the antennae have the highest representation with 645 species, followed by modified clypeus with 181 species. Modifications of the head occur in 756 species or 58% of the total modified Galerucinae, and of these 645 species have modified antennae (50% of the total) also higher than modifications found in other parts of the body, such as thorax and abdomen.Generally, the distribution of modified structures on a body part is associated with their function. Modified structures on the head may be associated with olfaction and to a lesser extent with some modified pronota and elytra having hairs or sensillae. Modified structures on the thorax, especially on the legs, are associated with precopulatory behaviour. Also the modified abdomen is associated with precopulatory behaviour. Details of these modified structures are discussed below.  There are certainly many more examples of SSCs of which we are not yet aware but will be discovered in the future. The record of Galerucinae having the SSC is growing. Since 2005, 78 species were described including 9 that were described in 2010 and recently 2 in 2011 (see AppendixB, list of species).


## 5. Peculiar Form of SSCs

Interestingly, the antennae and tarsal claws are two characters that have some of the most peculiar forms of SSCs in the Galerucinae. Usually the number of antennal segments is the same in both males and females, that is, 11 segments in almost all the Galerucinae, and fewer than that in a few genera of the subfamily Alticinae (sensu stricto), for example, 9 segments in NonarthraBaly, and 10 segments in PsylliodesLatreille  Monotalla Bechyné, and DeciplatusLinzmeier and Konstantinov. However, in a couple genera of Galerucinae, there is a difference in the antennal segments between male and female. In OroetesJacoby and PhyllectrisDejean the males have 10 antennal segments (O. flavicollis, P. gentilis(Leconte)) compared with females having 11 segments. There is no apparent explanation as to why the male has less segments than the female.It is common for both males and females to possess the same characteristics of the tarsal claws, either simple, bifid, or appendiculate. However, inApophylia, the males have bifid tarsal claws versus appendiculate claws in the females, and in ErynephalaBlake, males also have bifid claws, but females have simple claws. The beetles of the genus Apophyliahave the elytral surfaces closely punctuate, appearing rugose. The same is true for the elytral surface of Erynephalathat have closely but moderately coarse punctures. Thus, it is speculated that the male uses its bifid tarsal claws to hold onto the rugose surface of the female elytra during copulation. Of course, there are many genera with both males and females with the same tarsal claws, either bifid or appendiculate and with the rugose elytra.


## 6. Functions of SSCs

More than 1000 species have SSCs with more than two modified structures, and some 100 species have three or more modified structures. The presence of more than one type of SSC is also known as having multiple sexual ornaments. There are several hypotheses attempting to explain why a male would have multiple sexual ornaments. One of these is themultiple messages hypothesis, which states that each trait display reflects only one aspect of the overall quality of the male, different ornaments, and therefore signal different kinds of properties in an individual [29].  Additional displays may serve to enhance the accuracy with which observers assess a single quality or serve to provide information about different qualities [30]. According to Moller and Pomiankowski [29], multiple sexual ornaments should be particularly common in taxa with the most intense sexual selection (i.e., lekking and other polygynous taxa). However, the SSCs are apparently not ornaments displayed by males to attract females. There is no variation in the SSCs among individuals within a species that would lead to intraspecific competition. Also, they are not weapons like the horns that are found in the other beetles, such as the Scarabaeidae or the jaws of Lucanidae. In these two families, the horns and jaws commonly function as weapons in the intraspecific battles [31].The majority of the SSCs are associated with sensory and olfactory functions particularly in the antennae and to some extent in elytra where glands are formed. The other modified structures of the SSCs are associated with copulatory behavior, and in some it is suspected to be involved in sound production.


### 6.1. Olfaction

Olfaction begins with transduction of the information carried by odor molecules into electrical signals in sensory neurons. The odor causes species-specific signal responses by the olfactory receptor neurons. Insect odor and taste receptors are highly sensitive detectors of food, mates, and oviposition sites, and these receptors have been identified in several insects [32]. The sense organs act as transducers in converting chemical energy into electrical energy of nerve impulses in sensory neurons to stimulate appropriate behavioural responses, such as finding food and mate and avoiding danger.As an olfactory organ, antennae are all provided with sensory receptors or sensillae. Usually, in a modified segment with gland, the segment is enlarged, oval, or rounded with an opening or pore, as inCerophysa flava (Figure 18), C. gestroi (Figure 19), Metacoryna guatemalensis(Figure 20), M. fulvipes(Figure 29), Ectmesopus darlingtoni(Figure 22), and Aulacophora luteicornis(Figure 23). The same is true with some modified elytra with cavities found in Malacorhinusspp. (Figures 61–63) and Androlyperus nataliae(Figure 64) that bear sensillae and glands [33]. The sensory receptors are densely located in the excavated antenna of Sarawakia ajaib(Figure 12) and Cerotoma ruficornis(Figure 26), clypeus of Palpoxenaspp. (Figures 5, 6, 8, and 9), and Eccoptopsis denticornis(Figure 7).


### 6.2. Copulatory Behavior

The SSC associated with copulatory behaviour is known as a nongenitalic male contact structure [12]. One common function of this structure is to grasp the female. The nongenitalic male structure, such as modified antennae and legs that are specialized to grasp and stimulate the female, is involved in intersexual competition [13]; thus, the tight grasping by the copulating male resists any attempt by another male to dislodge the copulation.There is a hypothesis about the interrelation between the genitalia and the secondary sexual characteristics (SSCs), wherein for a small and poorly sclerotized aedeagus, there is a provision for compensation in external structures [12, 13]. For example, recently, Konstantinov and Korotyaev [34] suggested that the male apionid beetle (Trichoconapion hirticone(Korotyaev)) probably used the three thickened apical antennal segments as a clasping organ during copulation since it has smaller aedeagus. In the genus Aulacophora,there is a relationship between the structure of aedeagus and the presence and absence of the nongenitalic characteristics [35]. A male species with a small and poorly sclerotized aedeagus is speculated to use the enlarged modified 3rd, 4th, and 5th antennal segments (Figures 32 and 33) function to grasp the female during copulation. It is speculated that other species in a number of genera with large modified middle antennal segments may possibly use these as a grasping organ (Malacorhinus antennatus(Jacoby) (Figure 35), Megalognatha femoralis(Laboissiere) (Figure 38)).This speculation is that when the leg functions as a grasping organ there is  a larger body size, or there is  some form of modification of the leg such as being curved or excised (emarginate or notched). The modified structures are found on various parts of the front, middle, and hind legs. Usually, only one part of a leg is modified, either the femur, tibia, tarsus, or tarsal claws.  For example, if the protibia is enlarged (Mombasa magna,Figure 66, Cerotoma dilatipes,Figure 67), the protibia excised (Taumacera tibialis,Figure 68), midtibia excised (T. midtibialis,Figure 69), and the metatibia curved with a spine (Scelolyperus tejonicus,Figure 70). The modified first segment of the protarsus being enlarged or strongly dilated is also known in males of other subfamilies of Chrysomelidae; however, in the Galerucinae, the modified tarsi are extremely large and with various shapes (e.g., Taumacera yamamotoi(Figure 71)). In the genus Apophylia,the presence of bifid tarsal claws, which are appendiculate in the female, possibly functions as grasping organs.Another nongenitalic male contact structures are found on the ventrite of the third segment of thorax, the metasternum, and the five visible abdominal sternites. In the modified metasternum, there are the median of the posterior margin, an extended process, or a pair of lobes. The function of these SSCs could possibly be associated in precopulatory behaviour; the metasternal process (Figures73 and 74) is used by the male to stroke the female. However, the appendages on the modified abdomen (Figures 75–88) are more complex, particularly in the genus Nymphius(Figures 82–88). It is also speculated that these appendages are used by the male to stroke the female during copulatory behaviour.


### 6.3. Sound Production

Sound produced through vibration and stridulation in animals, including insects, provides information used in predator-prey interactions, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions [36].  Two examples from various studies on insect sound production are the termite Zootermopsis angusticollis(Hagen) that bangs its head to produce a substrate-borne vibration as an alarm signal of a disturbance to the nest by predators [37], and the leaf-cutter ant, Atta cephalotes (Linnaeus), that produces a stridulation sound using a file and scrapper mechanism for communication. Foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations are used by the hitchhikers to locate workers engage in leaf cutting [38].It is suspected that some of the SSCs in the Galerucinae are involved in producing sound, and that such  devices are located in every part of the body, the antenna, pronotum, scutellum, elytron, leg, and abdomen [39]. Stridulation  is produced by  a file and scraper mechanism. Two species of KinabaluaMohamedsaid and nine species of XenodaBaly of the subgenus Xenoda(sensu stricto) have modified antennae with stridulatory devices. Figure 27 shows Kinabalua musaamaniMohamedsaid with antennal 8th segment bearing a long spine and 7th segment bearing a series of pegs on basal third. Xenoda species (Figures 39 and 40) has antennal segment 8 bearing a long spine and segment 9 bearing a series of pegs on the apical area. In the modified antennae mentioned above, the spine functions as a scraper and is pulled over the pegs stridulation is produced.In some species of the following genera:Cannonia(Figure 42), Laetiacantha(Figures 44 and 45),and Prosmidia(Figure 43), the modified pronotum has a short process in the middle of the posterior margin. It is suspected that when the pronotal process (scrapper) is pulled over the surface of scutellum (file), stridulation occurs. This type of sound could also be produced by modified elytra of Prosmidiathat has a pair of tubercles located at the base, between scutellum and humeri. It is speculated that during elytral movement, the basal tubercles come into contact with the posterior margin of pronotum and stridulation occurs.Generally, as discussed above, the modified structures found on legs are associated with copulatory behaviour. But in some Galerucinae, some are suspected to be involved in sound production using a file and scrapper mechanism. These stridulation devices are found on the metatrochanter, mesotibia, and tarsi. In the following three speciesCoeligetes borneensisMohamedsaid (Figure 65), Liroeties spinipes(Oglobin), andMonolepta trochanterinaMohamedsaid, the metatrochanter bears a long pointed appendage. This trochanter which moves vertically allows the spine to rub the abdominal sternite covered with series of pegs to produce sound. In males of Momaea distincta(Figures 71(a) and 71(b)) on the middle leg, the first segment of tarsus bears a long process pointing towards an excavated area at the apex of tibia that is covered with a series of pegs. Stridulation occurs when the tarsal process (scrapper) is pulled over the series pegs on the tibia.There are cases of modified elytra with a pair of tubercles located at the apex that are suspected to produce vibrational sound. Vibration can provide a channel of communication between males and females during mating when no stridulation occurs. The tubercle is hollow, thus when tapped on the abdomen a type of vibrational sound may be produced. It is like when one cups one’s hand and taps on a surface, it produces a sound that is different compared with tapping an open hand. Amazingly, in the genusDiacanthaalone, there are 81 species with males having modified elytra in a series of various-shaped tubercles. These tubercles may produce different vibrational sounds. Elytra with this type of tubercle are also found in some species of Paratriariusand one species of Sonchia.The presence of sound production devices in some of the Galerucinae (sensu stricto) is very interesting and has great potential for future research. It had been reported in other subfamilies of the Chrysomelidae, such as the Megalopodinae, Zeugophorinae, Criocerinae, Clytrinae, Hispinae, and Cassidinae [40–42].


### 6.4. Unknown Function

For some SSCs, there is no apparent explanation as to their functions. The following are some examples: first antennal segment enlarged (Aulacophora cornuta(Figure 4) and Taumacera khalednordini(Figure 24)), vertex strongly broadly depressed (Monolepta flavicollis(Figure 1)), vertex  longitudinally grooved (Aulacophora frontalis(Figure 2)), frons excavated with a projection (Lamprocopaspp.), clypeus transversely, deeply depressed (Cerotoma atrofasciata(Figure 3)), clypeus excavated with projections or spines (Palpoxena sumatrensis(Figure 6), Eccoptopsis denticornis(Figure 7), Palpoxena coerulipennis(Figure 9)), labrum extremely large (Palpoxenaspp. (Figures 8–10)), maxillary palpi large (Palpoxena laeta(Figure 11)), larger eyes in the males of 35 species and 12 genera (Table 2), pronotum excavated with projection (Jacobya cavicollis(Figure 41)), scutellum excavated, with sides raised into  high ridges (Halysacantha weisei(Jacoby)), elytra longitudinally carinate  (Candezea bicostata(Figure 52)), and elytra with cavities or extrusions in Paleosepharia(Figures 54–58) and some species of Monolepta(Figure 59), Pseudocrania(Figure 60), Parideaspp., and Pseudocophoraspp.


## 6.1. Olfaction

Olfaction begins with transduction of the information carried by odor molecules into electrical signals in sensory neurons. The odor causes species-specific signal responses by the olfactory receptor neurons. Insect odor and taste receptors are highly sensitive detectors of food, mates, and oviposition sites, and these receptors have been identified in several insects [32]. The sense organs act as transducers in converting chemical energy into electrical energy of nerve impulses in sensory neurons to stimulate appropriate behavioural responses, such as finding food and mate and avoiding danger.As an olfactory organ, antennae are all provided with sensory receptors or sensillae. Usually, in a modified segment with gland, the segment is enlarged, oval, or rounded with an opening or pore, as inCerophysa flava (Figure 18), C. gestroi (Figure 19), Metacoryna guatemalensis(Figure 20), M. fulvipes(Figure 29), Ectmesopus darlingtoni(Figure 22), and Aulacophora luteicornis(Figure 23). The same is true with some modified elytra with cavities found in Malacorhinusspp. (Figures 61–63) and Androlyperus nataliae(Figure 64) that bear sensillae and glands [33]. The sensory receptors are densely located in the excavated antenna of Sarawakia ajaib(Figure 12) and Cerotoma ruficornis(Figure 26), clypeus of Palpoxenaspp. (Figures 5, 6, 8, and 9), and Eccoptopsis denticornis(Figure 7).


## 6.2. Copulatory Behavior

The SSC associated with copulatory behaviour is known as a nongenitalic male contact structure [12]. One common function of this structure is to grasp the female. The nongenitalic male structure, such as modified antennae and legs that are specialized to grasp and stimulate the female, is involved in intersexual competition [13]; thus, the tight grasping by the copulating male resists any attempt by another male to dislodge the copulation.There is a hypothesis about the interrelation between the genitalia and the secondary sexual characteristics (SSCs), wherein for a small and poorly sclerotized aedeagus, there is a provision for compensation in external structures [12, 13]. For example, recently, Konstantinov and Korotyaev [34] suggested that the male apionid beetle (Trichoconapion hirticone(Korotyaev)) probably used the three thickened apical antennal segments as a clasping organ during copulation since it has smaller aedeagus. In the genus Aulacophora,there is a relationship between the structure of aedeagus and the presence and absence of the nongenitalic characteristics [35]. A male species with a small and poorly sclerotized aedeagus is speculated to use the enlarged modified 3rd, 4th, and 5th antennal segments (Figures 32 and 33) function to grasp the female during copulation. It is speculated that other species in a number of genera with large modified middle antennal segments may possibly use these as a grasping organ (Malacorhinus antennatus(Jacoby) (Figure 35), Megalognatha femoralis(Laboissiere) (Figure 38)).This speculation is that when the leg functions as a grasping organ there is  a larger body size, or there is  some form of modification of the leg such as being curved or excised (emarginate or notched). The modified structures are found on various parts of the front, middle, and hind legs. Usually, only one part of a leg is modified, either the femur, tibia, tarsus, or tarsal claws.  For example, if the protibia is enlarged (Mombasa magna,Figure 66, Cerotoma dilatipes,Figure 67), the protibia excised (Taumacera tibialis,Figure 68), midtibia excised (T. midtibialis,Figure 69), and the metatibia curved with a spine (Scelolyperus tejonicus,Figure 70). The modified first segment of the protarsus being enlarged or strongly dilated is also known in males of other subfamilies of Chrysomelidae; however, in the Galerucinae, the modified tarsi are extremely large and with various shapes (e.g., Taumacera yamamotoi(Figure 71)). In the genus Apophylia,the presence of bifid tarsal claws, which are appendiculate in the female, possibly functions as grasping organs.Another nongenitalic male contact structures are found on the ventrite of the third segment of thorax, the metasternum, and the five visible abdominal sternites. In the modified metasternum, there are the median of the posterior margin, an extended process, or a pair of lobes. The function of these SSCs could possibly be associated in precopulatory behaviour; the metasternal process (Figures73 and 74) is used by the male to stroke the female. However, the appendages on the modified abdomen (Figures 75–88) are more complex, particularly in the genus Nymphius(Figures 82–88). It is also speculated that these appendages are used by the male to stroke the female during copulatory behaviour.


## 6.3. Sound Production

Sound produced through vibration and stridulation in animals, including insects, provides information used in predator-prey interactions, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions [36].  Two examples from various studies on insect sound production are the termite Zootermopsis angusticollis(Hagen) that bangs its head to produce a substrate-borne vibration as an alarm signal of a disturbance to the nest by predators [37], and the leaf-cutter ant, Atta cephalotes (Linnaeus), that produces a stridulation sound using a file and scrapper mechanism for communication. Foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations are used by the hitchhikers to locate workers engage in leaf cutting [38].It is suspected that some of the SSCs in the Galerucinae are involved in producing sound, and that such  devices are located in every part of the body, the antenna, pronotum, scutellum, elytron, leg, and abdomen [39]. Stridulation  is produced by  a file and scraper mechanism. Two species of KinabaluaMohamedsaid and nine species of XenodaBaly of the subgenus Xenoda(sensu stricto) have modified antennae with stridulatory devices. Figure 27 shows Kinabalua musaamaniMohamedsaid with antennal 8th segment bearing a long spine and 7th segment bearing a series of pegs on basal third. Xenoda species (Figures 39 and 40) has antennal segment 8 bearing a long spine and segment 9 bearing a series of pegs on the apical area. In the modified antennae mentioned above, the spine functions as a scraper and is pulled over the pegs stridulation is produced.In some species of the following genera:Cannonia(Figure 42), Laetiacantha(Figures 44 and 45),and Prosmidia(Figure 43), the modified pronotum has a short process in the middle of the posterior margin. It is suspected that when the pronotal process (scrapper) is pulled over the surface of scutellum (file), stridulation occurs. This type of sound could also be produced by modified elytra of Prosmidiathat has a pair of tubercles located at the base, between scutellum and humeri. It is speculated that during elytral movement, the basal tubercles come into contact with the posterior margin of pronotum and stridulation occurs.Generally, as discussed above, the modified structures found on legs are associated with copulatory behaviour. But in some Galerucinae, some are suspected to be involved in sound production using a file and scrapper mechanism. These stridulation devices are found on the metatrochanter, mesotibia, and tarsi. In the following three speciesCoeligetes borneensisMohamedsaid (Figure 65), Liroeties spinipes(Oglobin), andMonolepta trochanterinaMohamedsaid, the metatrochanter bears a long pointed appendage. This trochanter which moves vertically allows the spine to rub the abdominal sternite covered with series of pegs to produce sound. In males of Momaea distincta(Figures 71(a) and 71(b)) on the middle leg, the first segment of tarsus bears a long process pointing towards an excavated area at the apex of tibia that is covered with a series of pegs. Stridulation occurs when the tarsal process (scrapper) is pulled over the series pegs on the tibia.There are cases of modified elytra with a pair of tubercles located at the apex that are suspected to produce vibrational sound. Vibration can provide a channel of communication between males and females during mating when no stridulation occurs. The tubercle is hollow, thus when tapped on the abdomen a type of vibrational sound may be produced. It is like when one cups one’s hand and taps on a surface, it produces a sound that is different compared with tapping an open hand. Amazingly, in the genusDiacanthaalone, there are 81 species with males having modified elytra in a series of various-shaped tubercles. These tubercles may produce different vibrational sounds. Elytra with this type of tubercle are also found in some species of Paratriariusand one species of Sonchia.The presence of sound production devices in some of the Galerucinae (sensu stricto) is very interesting and has great potential for future research. It had been reported in other subfamilies of the Chrysomelidae, such as the Megalopodinae, Zeugophorinae, Criocerinae, Clytrinae, Hispinae, and Cassidinae [40–42].


## 6.4. Unknown Function

For some SSCs, there is no apparent explanation as to their functions. The following are some examples: first antennal segment enlarged (Aulacophora cornuta(Figure 4) and Taumacera khalednordini(Figure 24)), vertex strongly broadly depressed (Monolepta flavicollis(Figure 1)), vertex  longitudinally grooved (Aulacophora frontalis(Figure 2)), frons excavated with a projection (Lamprocopaspp.), clypeus transversely, deeply depressed (Cerotoma atrofasciata(Figure 3)), clypeus excavated with projections or spines (Palpoxena sumatrensis(Figure 6), Eccoptopsis denticornis(Figure 7), Palpoxena coerulipennis(Figure 9)), labrum extremely large (Palpoxenaspp. (Figures 8–10)), maxillary palpi large (Palpoxena laeta(Figure 11)), larger eyes in the males of 35 species and 12 genera (Table 2), pronotum excavated with projection (Jacobya cavicollis(Figure 41)), scutellum excavated, with sides raised into  high ridges (Halysacantha weisei(Jacoby)), elytra longitudinally carinate  (Candezea bicostata(Figure 52)), and elytra with cavities or extrusions in Paleosepharia(Figures 54–58) and some species of Monolepta(Figure 59), Pseudocrania(Figure 60), Parideaspp., and Pseudocophoraspp.


## 7. Utilization of the SSC

### 7.1. Identification of the Sex

The presence of SSCs has long been utilized as tool for sex identification. According to Hinton [43], a rapid and accurate method of sexing bark beetle is valuable, but the absence of SSCs in the adult confused flour beetle, Tribolium confusumDuval, and the rust-red flour beetle, T. castaneumHerbst, means that the beetles could only be sexed in the pupal stage, a procedure which is frequently very inconvenient. Schmitz and Furniss [44] reported the relative accuracy and usefulness of SSCs as sex indicators in Scolytus laricisBlackman. Recently, French and Hammack [45] show that the presence of SSC in the tarsal segment of corn rootworms and bean leaf beetles facilitates sex identification, which is very useful for modelling and management purposes.


### 7.2. Subfamily Taxonomy

There are 1298 species and 172 genera of Galerucinae with at least one type of SSC. The number of species known to have SSCs represents about 24% of the total known Galerucinae, estimated as 5500 [2]. This is significant representation. A high number of Galerucinae with SSCs indicate a large amount of information or data that can be utilized to understand the subfamily in relation to other subfamilies of Chrysomelidae.Taxonomically, of course, all modified structures are significant at the species level and to some extent at the generic level. Table4 provides a summary of modified characteristics found in 49 largest genera. The modified characteristics tabulated in Table 4 are generally distinctive for the respective genera. Not much has been written about the significance of the modified characteristics at the subfamily level, except for the antennae. Jolivet [46] highlighted some Galerucinae with modified antennae and noted that compared to other Chrysomelidae this subfamily possesses the greatest diversity in antennal shape. Mohamedsaid [47] provided a general review on some modified antennae of Malaysian Galerucinae. The degree of antennal modification is much greater, not only in terms of their larger size, but also in terms of shape that to some extent may be extremely distorted or deformed. Much earlier, Maulik [17] concluded that such antennal modifications common in the Galerucinae are not found in any other subfamily, not even in the very closely allied Alticinae. However, the present study provides all types of SSCs in the form of many modified structures, including the antennae, found on all parts of the body, the head, thorax, and abdomen. A summation of all these modified characteristics documents its taxonomic significance with respect to the subfamily Galerucinae and continues to demonstrate additional differences of the Galerucinae (sensu stricto) from other subfamilies, especially the Alticinae.There are some modified structures present in other subfamilies of Chrysomelidae, but they are not comparable in terms of representation within a subfamily and complexity of the modifications or the numbers of taxa found in the Galerucinae. This begs the question as to why this phenomenon of the SSCs is so prevalent and somewhat unique for these characters of the Galerucinae and that this may reflect its position in the Chrysomelidae.  This SSC phenomenon is somewhat similar to the correlation of other morphological systems (e.g., aedeagus, spermatheca, and wing venation) of the Alticinae/Galerucinae that demonstrate either a Galerucinae or Alticinae tendency at the generic level [48].  Various authors have made the general statement that there are no differences between larvae of the Galerucinae (sensu stricto) and the Alticinae (sensu stricto) [49–52], but larval studies of the Galerucinae and Alticinae are far from comprehensive and without worldwide representation, that is, poor taxon sampling [53].  Besides, similarities between larvae of certain alticine and galerucine groups may be more closely tied to convergence such as habitat than to actual ancestral identity, that is, relationships [20].An adult galerucine with the modified characteristics is clearly different from other congeneric adults without modifications. It is not known whether certain larvae of the modified adults are different from the larvae of nonmodified adults. Despite the apparently similar larval morphology, the second author has always maintained that the characteristic of the metafemoral spring (found in both sexes) is unique to and primarily defines the Alticinae, and it differentiates this subfamily from the Galerucinae (sensu stricto) [6].  This characteristic also has the very useful aspect that it can be used to distinguish genera in the vast majority of cases because of its consistent morphology in all species of each genus [54–56].  One study that tried to demonstrate that the metafemoral spring was variable within a genus [7] failed to recognize that when the spring is taken out of the metafemur and allowed to dry out its very thin chitinous structure shrivels up differently depending on many factors such as how it was treated (e.g., chemicals, temperature, etc.) during extraction; therefore, the conclusion in that reference that the metafemoral spring is not a valid intrageneric character is erroneous.


## 7.1. Identification of the Sex

The presence of SSCs has long been utilized as tool for sex identification. According to Hinton [43], a rapid and accurate method of sexing bark beetle is valuable, but the absence of SSCs in the adult confused flour beetle, Tribolium confusumDuval, and the rust-red flour beetle, T. castaneumHerbst, means that the beetles could only be sexed in the pupal stage, a procedure which is frequently very inconvenient. Schmitz and Furniss [44] reported the relative accuracy and usefulness of SSCs as sex indicators in Scolytus laricisBlackman. Recently, French and Hammack [45] show that the presence of SSC in the tarsal segment of corn rootworms and bean leaf beetles facilitates sex identification, which is very useful for modelling and management purposes.


## 7.2. Subfamily Taxonomy

There are 1298 species and 172 genera of Galerucinae with at least one type of SSC. The number of species known to have SSCs represents about 24% of the total known Galerucinae, estimated as 5500 [2]. This is significant representation. A high number of Galerucinae with SSCs indicate a large amount of information or data that can be utilized to understand the subfamily in relation to other subfamilies of Chrysomelidae.Taxonomically, of course, all modified structures are significant at the species level and to some extent at the generic level. Table4 provides a summary of modified characteristics found in 49 largest genera. The modified characteristics tabulated in Table 4 are generally distinctive for the respective genera. Not much has been written about the significance of the modified characteristics at the subfamily level, except for the antennae. Jolivet [46] highlighted some Galerucinae with modified antennae and noted that compared to other Chrysomelidae this subfamily possesses the greatest diversity in antennal shape. Mohamedsaid [47] provided a general review on some modified antennae of Malaysian Galerucinae. The degree of antennal modification is much greater, not only in terms of their larger size, but also in terms of shape that to some extent may be extremely distorted or deformed. Much earlier, Maulik [17] concluded that such antennal modifications common in the Galerucinae are not found in any other subfamily, not even in the very closely allied Alticinae. However, the present study provides all types of SSCs in the form of many modified structures, including the antennae, found on all parts of the body, the head, thorax, and abdomen. A summation of all these modified characteristics documents its taxonomic significance with respect to the subfamily Galerucinae and continues to demonstrate additional differences of the Galerucinae (sensu stricto) from other subfamilies, especially the Alticinae.There are some modified structures present in other subfamilies of Chrysomelidae, but they are not comparable in terms of representation within a subfamily and complexity of the modifications or the numbers of taxa found in the Galerucinae. This begs the question as to why this phenomenon of the SSCs is so prevalent and somewhat unique for these characters of the Galerucinae and that this may reflect its position in the Chrysomelidae.  This SSC phenomenon is somewhat similar to the correlation of other morphological systems (e.g., aedeagus, spermatheca, and wing venation) of the Alticinae/Galerucinae that demonstrate either a Galerucinae or Alticinae tendency at the generic level [48].  Various authors have made the general statement that there are no differences between larvae of the Galerucinae (sensu stricto) and the Alticinae (sensu stricto) [49–52], but larval studies of the Galerucinae and Alticinae are far from comprehensive and without worldwide representation, that is, poor taxon sampling [53].  Besides, similarities between larvae of certain alticine and galerucine groups may be more closely tied to convergence such as habitat than to actual ancestral identity, that is, relationships [20].An adult galerucine with the modified characteristics is clearly different from other congeneric adults without modifications. It is not known whether certain larvae of the modified adults are different from the larvae of nonmodified adults. Despite the apparently similar larval morphology, the second author has always maintained that the characteristic of the metafemoral spring (found in both sexes) is unique to and primarily defines the Alticinae, and it differentiates this subfamily from the Galerucinae (sensu stricto) [6].  This characteristic also has the very useful aspect that it can be used to distinguish genera in the vast majority of cases because of its consistent morphology in all species of each genus [54–56].  One study that tried to demonstrate that the metafemoral spring was variable within a genus [7] failed to recognize that when the spring is taken out of the metafemur and allowed to dry out its very thin chitinous structure shrivels up differently depending on many factors such as how it was treated (e.g., chemicals, temperature, etc.) during extraction; therefore, the conclusion in that reference that the metafemoral spring is not a valid intrageneric character is erroneous.


## 8. Conclusion

There are 1298 species in the subfamily Galerucinae (sensu stricto) with at least one type of sexual secondary characteristics (SSCs). This figure represents 24% of the total members of the subfamily and is a very significant number. The SSCs are so diverse, with modified structures found on every part of the body (head, thorax, and abdomen) and with functions encompassing olfactory and copulatory behaviour, as well as sound production. The presence of SSCs as stridulatory devices functioning to produce sound is certainly a significant characteristic of the subfamily Galerucinae (sensu stricto). The SSCs are not variable but are species specific. They are variable interspecifically a manifestation of amazing biodiversity of the Galerucinae with SSCs. Modified Galerucinae are unparalleled in other subfamily of the Chrysomelidae. Despite reputed larval similarities, these apomorphic characteristics of adult Galerucinae distinguish them from the Alticinae. A high representation of SSCs indicates that they are not exceptional but a characteristic of the subfamily Galerucinae (sensu stricto). These characteristics should be fully utilized in our attempt to understand the Galerucinae and its relationships with other subfamilies in the Chrysomelidae.



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*Source: 328670-2011-05-10.xml*