Eotania
Creators: name: Carle, Frank Louis
name: Kjer, Karl M.
Publisher: name: Zenodo
Year: 2002
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Eotania

description: Eotania subgenus nov.
Type Species: Mesothemis composita Hagen
Length: 42­49mm; abdomen 30­32mm; hind wing 35­37mm.
Distribution: USA (AZ, CA, KS, NV, NM, OR, TX, UT, WY).
Adult ­ Face white with anterior edge of labrum black, dorsum of vertex and occiput white, compound eyes pearly white. Posterior margin of prothorax low and rounded. Middorsal pterothoracic white stripe extended over 1 / 2 of mesanepisterna, pterothorax laterally white with black stripes along meso­ and metapleural sulci, interpleural suture black to level of spiracle, legs black with basal half of outer femoral face pale. Wings hyaline with saffron stain extended outward to about arculus, female with nodal brown spots, costa white, and pterostigmata brown. Triangles 2­3 / 1­2 celled, fore wing subtriangle 3­4 celled, bridge crossveins 2­3, hind wing antenodals 10­12, and forewing cubital planate wth 2 cell rows. Abdomen black with submedian row of pale spots on segments 1­3 in male, and 1­8 in female. Abdominal sternum 1 without hooks, anterior lamina angled ventrally at about 30 degrees, and posterior hamuli with well developed endhook and shoulder. Tergum 9 without lateral carinae. Male cerci only slightly widened distally. Penis with low hood, with elongate lateral lobes with apices curved dorsally, with cornual base expanded with dense dorsal cover of erectile hair, and with lateral cornua short­robust.
Larvae­ Head expanded posterior to compound eyes. Abdomen with apical submedian brown stripes, dorsal abdominal hooks absent or at most humplike, and lateral abdominal spines obsolete.
Morphological characters
The principal characters utilized in our analysis are those of the wing venation and coloration, and those of the male secondary genitalia. Many of the characters utilized are well illustrated in Needham, Westfall, and May (2000), and will be referred to in the following format: (NWM Fig.00x­z). Head characters are used only three times in the analysis of Libelluloid phylogeny with the most important, (Character 27 c in Appendix 1), involving the posterior border of adult compound eye (NWM Fig. 28 c­d). Leg characters are used to distinguish Macromiinae, which are characterized by a long ventral tarsal claw (NWM Fig. 430 d). Two thoracic characters are utilized;, they are the sinuous mesoplueral sulci (Garman 1927, Fig. 40 a­b), and the bilobate hind margin of the prothorax (Borror 1945, Figs. 37­43). Abdominal characters involve the shape of the abdomen and the development of transverse and lateral carinae. In addition, eight abdominal coloration characters are utilized and an additional three are concerned with the degree of pruinosity, a waxy covering which typically obscures the color patterns of males. The submedian abdominal pale spots are used in four characters (NWM Fig. 29 b).
The terminology of wing venation used in this analysis is basically that of Needham, Westfall, and May (2000), (NWM Fig. 7). The costal pleat is well developed between the wing base and nodus, and crossveins within this space are referred to as antenodals and, when these are aligned and strengthened, they are called costal braces. Hind wing with 9 plus costal braces (character 33 a), is a conservatively stated character, as most Libelulini have more than 11 costal braces. Beyond the nodus the subcostal vein fuses to the costa so that postnodal crossveins are located to either side of the radial vein. Character 35 b, forewing with 4­5 unmatched postnodals, refers to the missing basal crossveins of the second postnodal series (compare NWM Fig. 10 to 444). The pterostigma is located near the end of the postnodal space, and characters include the number of crossveins beyond the hind wing pterostigma, position of the pterostigmal brace (the pterostigmal brace is located in the second postnodal interspace typically at the proximal end of the pterostigma), pterostigmal shape (NWM Fig. 428), and the relative length of the pterostigma. Perhaps the most distinctive feature of Anisopteran venation are the triangles: characters utilized include base of hind wing triangle at or near arculus (NWM Fig. 26), cubital vein arises from outer side of triangle, (compare NWM Fig. 426 to 427), and forewing subtriangle with more than 3 cells. The anal loop of Libelulidae forms a strong pleat which supports the anal region of the wing, and in higher Corduliinae and Libellulinae the anal loop has a well developed midrib (NWM Fig. 426). Further characters involve development of the anal loop toe, development of the "heel angle" of anal loop bisector, and development of the spur (NWM Fig. 426). Other venational characters include the number of bridge crossveins (NWM Fig. 10), vein M 2 strongly undulate (compare NWM Fig. 425 to 485), and forewing cubital planate with 2­3 cell rows (labeled as Mpl on NWM Fig. 425). In addition, fifteen wing coloration characters are utilized; they involve the presence, color, and relative size of basal, nodal, and apical wing spots; and the color of the costa and pterostigma.
The male secondary genitalia are unique to the Odonata and include the most important systematic characters in the group; in Libellulidae the anterior hamuli and apical penile segment are reduced (compare NWM Fig. 12 to 435). The penile terminology used in this analysis is basically that of Kennedy (1922 a), and because many of the characters utilized are well illustrated in Kennedy (1922 b) his drawings will be referred to in the following format: (K Plate 0 Fig.00). Of the 31 genitalic characters utilized to determine libellulid phylogeny only five do not involve penile characters. Among these are the unique ventral process on abdominal segment 1 of male Plathemis and Platetrum (NWM Fig. 528). In addition, the degree of uplift of the anterior lamina distinguishes Eotania from Neotetrum­Holotania (NWM Fig. 489). The shape of the posterior hamuli is also quite distinctive among subgenera of Libellula: the stubby boxing­glove­like type is characteristic of the Platetrum­Ladona groups, in other Libellula it is more hook­like with a reduced shoulder (compare NWM Fig. 489 to 528). The penile characters utilized in this analysis primarily involve the shape of the apical segment, the shape of the lateral lobes, and the development of the cornua (Kennedy 1922 a, b).
Phylogenetic results
Figure 1 shows the results of our phylogenetic analysis. Corduliinae is divided into a paraphyletic group by character sets 25 and 26. Sympetrini (Tillyard 1917, Tillyard and Fraser 1940, Fraser 1957, Davies 1981, Bridges 1994) is found to be polyphyletic and not the sister group of Libellulini. Trameini is rather closely related to Libellulini, and Orthemis is the sister group of Libellula sensu lato (s.l.) within our taxon sample. Libellula (s.l.) is divided into four basal monophyletic groups: Platetrum­Plathemis, Eurothemis­Ladona, Libellula­Syntetrum­Eolibellula, and Belonia­Neotetrum­Holotania­Eotania subgen. nov. Belonia is found to be monophyletic and the sister group of the remaining subgenera of group four, and Eotania subgen. nov. is found to be the sister group of Neotetrum­Holotania. Monophyly for most named taxa are well supported as indicated by both high bootstrap values (Fig. 1) and the high congruence of independent character sets shown in the sorted data matrix (Appendix 2).
Discussion
The phylogenetic topology of basal libelluloides closely mirrors the breakup of Pangaea (Carle 1995). Cordulegastridae are limited to Laurasia; Neopetaliidae to Chile; Chlorogomphidae to India, Southeast Asia, and Japan; Synthemistidae to Tasmania, Australia, New Guinea, and New Caledonia; and the gomphomacromiids and basal corduliines to Australia, Andean South America, South Africa, and Madagascar. In tropical Africa and Southeast Asia basal Corduliinae are not represented, and in contrast, the Libellulinae, the species of which comprise nearly 70 % of all Libelluloidea, exhibits its greatest diversity (Davies 1981). Determining what corduliine group has given rise to Libellulinae will undoubtedly effect the placement of Libellulini within Libellulinae.
Unlike Corduliinae, Libellulinae are a monophyletic group well defined by uncorrelated apomorphic character states; these include: posterior margin of compound eye evenly curved, mesopleural sulci sinuous, and abdominal terga 2 and 3 with transverse carinae (Carle 1995). An additional apomorphy not included in our analysis is secondary genitalia with a unique filling and ejaculatory mechanism (Pfau 1991). Characteristics most often utilized to define Libellulinae are the well developed toe of the anal loop, and in males, the lack of tibial keels, lack of the hind wing angulation, and lack of auricles (denticulate lateral tubercles of abdominal segment 2). However, the anal loop is typically obsolete in Tetrathemini, and the toe of the anal loop is typically obsolete in Brachydiplacini. In addition, the loss characters of libelluline males are correlated and also typical of Hemicordulia (Corduliinae), Anatogaster (Cordulegastridae), and Anax (Aeshnidae). The well developed lateral abdominal carinae and elongate bisectored anal loop of higher Corduliinae combined with the loss of male auricles, hind wing angulation, and mesotibial keels in Hemicordulia, suggest that even the higher corduliines are paraphyletic as implied by the classifications of Bechly (1996) and Lohman (1996). In addition, the occurrence of Hemicordulia from Tasmania to Southeast Asia and Madagascar, support the evolution of Libellulinae from the higher vagile Corduliinae, and not from the peripherally isolated gomphomacromiid­like corduliines.
At least 13 tribes are currently recognized within Libellulinae and in this analysis we have included representative genera from Leucorrhiniini (Celithemis), Libellulini (Orthetrum, Orthemis, Libellula), Sympetrini (Sympetrum, Tarnetrum, Pachydiplax, Erythemis, Crocothemis), Palpopleurini (Perithemis), and Trameini (Tramea). Needham and Broughton (1927) presented a genealogical tree of Libellulinae based on venation and placed the Sympetrini as the sister group of Libellulini according to similarities in the anal loop. A more basal clade of their tree included Perithemis, Celithemis, and Crocothemis, and yet a more basal clade included Tramea. Within the Libellulinae sampled here Perithemis, Celithemis, Sympetrum, Tarnetrum, Pachydiplax, and Erythemis are characterized by an erect bilobate posterior margin of the prothorax and most are also characterized by a well developed spur vein or heel area of the anal loop. In stark contrast to the results of Needham and Broughton (1927), this group forms the sister group to a clade composed of Tramea, Crocothemis, and Libellulini (Fig. 1). Fraser (1957) placed Celithemis in Leucorrhiniini and considered it near Sympetrini; this is consistent with its position as shown in Fig. 1. Again in contrast to our results, Needham and Broughton (1927) removed Celithemis from Sympetrini, and placed it within a newly established Celithemini composed of Palpopleurini, Macrodiplacini, and other assorted genera including Crocothemis. Based on the 9 plus antenodals in the hind wing, Crocothemis in this taxon sample actually forms the sister group to Libellulini.
Apomorphies of Libellulini include an undulate M 2 vein, male abdomen pruinose, abdomen short and wide, reduction in width of anal field, and an increase in venational density. The Neotropical Cannaphila Kirby also fits quite well within Libellulini, but lacks a strongly undulate M 2 vein. Based on 5 or more crossveins beyond the pterostigma, Orthemis rather than Orthetrum is the sister group to Libellula s.l. within this taxon sample. Orthemis also shares short robust penile segments with Libellula, has the posterior hamuli somewhat boxing­glovelike, and has paired lateral cornua which are similar to those of L. (Eolibellula) semifasciata Burmeister, L. (Libellula) quadrimaculata, and L. (Syntetrum) angelina Selys. Placement of Orthemis together with Plathemis as the sister group of remaining Libellula s. l. (Artiss et al. 2001), is not supported by our analysis. Synapomorphies of Libellula include fore wing with 4­5 unmatched postnodals, wings with 2­6 bridge crossveins, basal brown area of fore wing extended to first antenodal (reversed at least 3 times), and abdomen wide (abdominal segment 5 wider than long, reversed at least 4 times). Our analysis divides the genus Libellula s.l. into three basal groups of 3 to 5 species which are laurasian in distribution and one basal group of 20 species that is nearctic in distribution. The first two groups are Eurothemis­Ladona, and Platetrum­Plathemis; they comprise the sister group to Libellula s.s. and are characterized by boxing glove­like posterior hamuli, lateral cornua which are short and wide at least basally, short wide lateral penile lobes (convergent to L. quadrimaculat a), and short wide abdomens with a white pruinessence (grayish in L. deplanata Rambur). Eurothemis and Ladona share similar wing and abdominal patterns and the dorsal fusion of the cornua. Eurothemis exhibits a remarkable expansion of the fused cornua and an associated apical elongation of the lateral lobes, this led Kennedy (1922 b) to place it as the sister taxon to Neotetrum. Although superficially similar, the cornual expansion in Neotetrum has its apex directed dorsally as opposed to anteroventrally in Eurothemis, suggesting that these expansions are not homologous. Although Artiss et al. (2001) did not confirm a close relationship between Platetrum and Plathemis, this, our second basal group is characterized by several synapomorphies including: male with ventral processes on abdominal sternum one, lateral penile lobes widened apically, third penile segment with a transverse trough, and abdominal segment 9 with lateral carinae. Both the Ladona­Eurothemis and Plathemis­Platetrum subgeneric pairs are separated by the North Atlantic Ocean; because none of these species are unusually vagile it is likely that they represent the isolated remnants of a transatlantic Miocene faunal split.
The third and fourth basal subgeneric groups of basal Libellula are: Eolibellula­Libellula­Syntetrum, and Belonia­Eotania­Holotania­Neotetrum. This group of seven subgenera share the presence of a medial penile cornua, have 2­3 cell rows subtended by the fore wing cubital planate (convergent to Plathemi s), and typically have nodal wing spots (lost three times). Kennedy (1922 b) considered the penis of our third group to be the most plesiotypic within Libellula and treated the group as paraphyletic. Accordingly Kennedy established two new subgenera so that all three subgenera in our basal group three are monotypic. Synapomorphies of group three include posterior hamuli hook­like, basal abdominal segments translucent, abdomen swollen basally and acuminate apically, and costa white (convergent to Eotania). However, the lateral penile cornua in group three are shorter than in either Orthemis or Belonia indicating that intermediate length cornua may also be a genuine synapomorphy for the group. Group three has a circumpolar distribution with Eolibellula found throughout eastern North America, with Synetrum restricted to Japan, and with Libellula quadrimaculata circumpolar. Similar wing patterns indicate that Eolibellula and Syntetrum might form a subgeneric pair with a distribution similar to the gomphid genus Lanthus, however it seems more likely that Syntetrum represents a peripheral isolate of Libellula quadrimaculata which later also dispersed into North America where it is now sympatric with Eolibellula.
The forth and largest basal group of Libellula, includes the subgenera Belonia, Eotania, Holotania and Neotetrum, is characterized by having the median cornua longer than the lateral cornua. All four subgenera are restricted to North America and the most basal species in each is found in either the south western United States or Central America, suggesting that this area was an important refugium for Libellula during glacial maxima. In contrast to the findings of Artiss et al. (2001) we do not find Belonia to be paraphyletic. Synapomorphies for Belonia include the reddish abdominal and wing color, and the unique penile cornua which are elongate, asymmetrical, and lined with short papillae. Based on shorter cornua and darker coloration, L. foliata (Kirby) and L. mariae Garrison, are the most basal Belonia. The penis of Eotania, Holotania, and Neotetrum is unique in that the lateral lobes are elongate and curved dorsally, and the cornual base is greatly expanded with a dense dorsal covering of erectile hair. Additional synapomorphies for this group include the erect posterior hamuli with a reduced shoulder, and the submedian line of pale abdominal spots. Kennedy (1922) considered Eotania to be the sister taxon to Holotania, probably based on the relatively short lateral penile lobes of Neotetrum. However several apomorphies are shared between Holotania and Neotetrum, these include: submedian pale areas confluent and contiguous with the lateral carina of terga 6­10, anterior lamina angled at about 45 degrees, third penile segment hood­like, lateral penile cornua obsolete, and forewing subtriangle typically with more than 3 cells. Therefore, Eotainia is here considered to be the sister taxon to Holotania ­ Neotetrum. Neotetrum and Holotania are distinguished primarily on the basis of penile characters, Neotetrum has the lateral penile lobes reduced to small up­curved rods and has a sharp medial ridge on the posterior face of the penile hood, Holotania is characterized by having the lateral penile lobes curved ventrally at apex, by having the penile hood produced posteroventrally, and by having the medial cornua elongate­recumbent. The less extensive wing markings and less reduced medial cornua indicate that L. nodisticta Hagen represents the most basal Neotetrum. Libellula luctuosa Burmeister and L. gaigei Gloyd comprise the sister group to remaining Holotania, synapomorphies for this pair include base of the wings opaque black or brownish red out to the nodus, and medial penile lobe of segment 3 hoodlike. Remaining Holotania are characterized by having an enlarged pterostigma which is about one half as long as the postnodal space. Libellula flavida Rambur, L. cyanea Fabricius, and L. comanche Calvert exhibit bicolored pterostigma, and in the latter two species the pterostigma are about half black and half white. Remaining Holotania are characterized by having the submedian abdominal pale areas confluent and contiguous with the lateral carina on segments 3­10. Speciation has apparently been quite rapid in the remaining Holotania so that many taxonomic characters involve reproductive isolation, and are quite homoplastic. Libellula axillena Westwood may be basal in this group due to its darker coloration, more robust build, and more extensive wing markings. Of the remaining species, Libellula incesta Hagen and L. vibrans Fabricius share a fingerlike extension of the penile hood, and L. jesseana Williamson, L. auripennis Burmeister, and L. needhami Westfall have red costa and the submedian abdominal pale areas confluent and contigious with the lateral carinae of segments 1­10. Libellula jesseana and L. auripennis share bright red pterostigmata in the mature male.
description: Published as part of Carle, Frank Louis & Kjer, Karl M., 2002, Phylogeny of Libellula Linnaeus (Odonata: Insecta), pp. 1-18 in Zootaxa 87 on pages 3-9, DOI: 10.5281/zenodo.155965