DOI: 10.15468/elgvvj
title: New ant species related to Cerapachys sexspinus and discussion of the status of Yunodorylus (Hymenoptera: Formicidae).

description: This dataset contains the digitized treatments in Plazi based on the original journal article Borowiec, M. L. (2009): New ant species related to Cerapachys sexspinus and discussion of the status of Yunodorylus (Hymenoptera: Formicidae). Zootaxa 2069: 43-58, URL: http://hol.osu.edu/reference-full.html?id=22781AbstractThree species related to the Chinese ant Cerapachys sexspinus (Xu, 2000) are described as new: Cerapachys doryloides n. sp. from Borneo, C. eguchii n. sp. from Vietnam, and C. paradoxus n. sp. from Borneo. Additionally, Cerapachys sexspinus is redescribed. A species-group diagnosis and a discussion of the group's affinities are provided, together with a key to species based on workers. All species are illustrated with photographs and a distribution map. It is recommended that the name Yunodorylus remain a synonym of Cerapachys until the taxonomy and phylogeny of the Cerapachyinae is better understood.Key words: ants, Formicidae, dorylomorphs, Cerapachyinae, Cerapachys, Yunodorylus, taxonomy, key, new species IntroductionIn 2000, Xu introduced Yunodorylus, a new genus name in the Formicidae. He described a single species, Y. sexspinus from Yunnan province, China, and placed the genus in the subfamily Dorylinae. Due to a unique character combination seen in these ants, namely a one-segmented waist and general habitus reminiscent of doryline ants on the one hand and presence of modified, peg-like setae on the pygidium and absence of promesonotal suture on the other hand, he concluded that Yunodorylus may be an "interlink" in the evolution of Cerapachyinae and Dorylinae. However, Bolton (2003) synonymized the genus with Cerapachys, because its definition clearly includes apomorphies of the Cerapachyinae and the assumption that Cerapachys can only possess two waist segments is not true, as had already been shown in Bolton (1990).Subsequently, Cerapachys sexspinus has been included in two important ant phylogenies, with ambiguous results. In Moreau et al. (2006) it appeared as sister group to Sphinctomyrmex, whereas in Brady et al. (2006) it appeared as sister group to an Aenictinae + Ecitoninae clade.The purpose of the present study is to describe the diversity of species related to C. sexspinus that has accumulated in collections since the original description, to provide a concise group diagnosis that can be related to other cerapachyines and to discuss group affinities based upon available data. An effort was undertaken to gain access to as much material of this group as possible. However, specimens collected in Thailand and reported as C. sexspinus by Jaitrong & Nabhitabhata (2005) have not been examined.Measurements, terms, and materialMeasurements were taken using Nikon SMZ 1500 and Wild M5A stereomicroscopes at 100X magnification with ocular micrometer. Color photographs were prepared using a Nikon SMZ 1500 stereomicroscope with a Nikon Coolpix 4500 digital photo camera (Figs. 1-8, 13-14) and Leica MZ 16 stereomicroscope with a JVC digital video camera (Figs. 9-12). All images were processed using CombineZP freeware, and cleaned and adjusted using Adobe Photoshop.HW Head width: Maximum width in full face view. Since in this group eyes are absent, the measurement is taken across the widest point.HL Head length: Maximum length along midline in full face view, from the anteriormost part of the head (anterior edge of frontal lobes) to the posterior margin.SL Scape length: Maximum length measured without condyle and neck.MH Mesosoma height: In side view, maximum height measured from the lowermost point of mesopleuron (in front of middle coxa) to dorsal edge of mesosoma.ML Mesosoma length: In side view, maximum longitudinal distance from posteroventral corner of mesosoma to the farthest point on anterior face of pronotum, excluding the neck.PrW Pronotal width: Maximum width in dorsal view.PW Petiole width: Maximum width of abdominal segment II in dorsal view.PL Petiole length: Maximum length of abdominal segment II in dorsal view, measuring only the length of petiolar tergite.IIIAW Third abdominal tergite width: Maximum width in dorsal view.IIIAL Third abdominal tergite length: Maximum length in dorsal view, measuring only the length of posttergite, excluding pretergite III (helcium).IVAW Fourth abdominal tergite width: Maximum width in dorsal view.IVAL Fourth abdominal tergite length: Maximum length in dorsal view, excluding pretergite.FFeW Front femur width: Maximum width in side view.All leg measurements below are taken as maximum length measured along extensor (outer) surface:FFeL Front femur length.HFeL Hind femur length.FTiL Front tibia length.HTiL Hind tibia length.FBaL Front basitarsus length.HBaL Hind basitarsus length.CI Cephalic index: HL/HWx100.MI Mesosomal index: ML/MHx100.PI Petiolar index: PL/PWx100.Measurements of the holotype worker are given first, followed by ranges for all specimens measured, including the holotype. All measurements are given in millimeters.Depositories:BMNH Natural History Museum, London, United Kingdom.CASC California Academy of Sciences, San Francisco, United States of America.MCZC Museum of Comparative Zoology, Harvard University, Cambridge, United States of America.ISAS Kunming Institute of Technology, Academia Sinica, Kunming, China.KEPC Katsuyuki Eguchi private collection, Nagasaki, Japan.MLBC Marek Borowiec private collection, Wroclaw, Poland.VNMN Vietnam National Museum of Nature, Hanoi, Vietnam.Two special terms used in this work are explained below.The term 'parafrontal ridges' is derived from Wilson's (1964) work on Aenictus, and is used for low lines running from lateral portions of clypeus laterad to antennal sockets, thus separating them from the genae. Such ridges are present in most Cerapachyini, but absent in many Sphinctomyrmex, all Acanthostichus and Cylindromyrmex.'Lateroclypeal tooth is here introduced for the modification of the lateral corners of the clypeus, which in cerapachyines can be variably developed, from being bluntly pointed to drawn into conspicuous teeth that project over the mandibles.Characters of the species-groupIn this contribution, an effort was taken to present a concise species-group diagnosis, enabling anyone working with Cerapachys material to distinguish these species from other groups. Modern species-group classification in Cerapachyinae is derived from work of Brown (1975), who recognized 18 informal groups in Cerapachys. However, he had not taken the diagnoses any further than providing very rudimentary remarks on characters such as number of antennal segments, size of the eyes, dorsolateral margination of various body parts, and geographical distribution. Apart from his preliminary key to species, he did not provide unique character combinations for each group that could constitute formal diagnoses. The present work included examination of a large amount of cerapachyine material in order to provide a good overview of characters relevant to diagnosing the sexspinus species-group.Diagnosis of sexspinus species-group based on worker casteAntennae with 11 or 12 segments. Apical antennal segment not conspicuously enlarged, equal or little longer than two preceding. Parafrontal ridges strongly reduced to absent (see note 1 below). Two ridges present behind frontal carinae with medial impression between them. Palp formula 2,2 (known in sexspinus, paradoxus). Mandibles triangular, crenulate or with denticles, or elongated, with teeth. Eyes in worker completely absent. Ventrolateral margins of the head capsule reduced to weakly pronounced ridge. Ocelli in workers absent. Pronotum not marginate anterodorsally, pronotal collar not separated from dorsal surface. Mesosoma, petiole and postpetiole not marginate dorsolaterally. Waist of a single segment, abdominal segment IV with very broad presclerites and weak constriction between pre- and postsclerites (see note 2 below). Fourth abdominal tergite not folding over sternite, and anterior portions of sternite and tergite are equally well visible in side view. Spur formula 2(1s, 1p), 2(1s, 1p) (see note 3 below). Middle and hind basitarsi not widening distally, circular in cross-section. Posterior flange of hind coxa not produced as raised lamella. Metatibial glands with no discernible orifice, visible as a lighter, round to elongate patch of cuticle devoid of pubescence. Pretarsal claws simple. Polymorphic (see note 4 below).Characters in italics are hypothetical autapomorphies of the group. They could not be seen in any other Cerapachys or other species of the Cerapachyinae available at the time of this study and are apparently unique for the whole subfamily.Note 1. Absence of parafrontal ridges is characteristic of this group but can be observed in at least one species outside the group, namely Australian Cerapachys edentatus (Forel, 1900). However, this unrelated species is easily distinguished by having 9 antennal segments and small abdominal segment III, differentiated as postpetiole. Many Sphinctomyrmex have parafrontal ridges reduced to absent. Since monophyly of both Cerapachys and Sphinctomyrmex is questioned (Brown 1975, Brady et al. 2006), at this point it is not possible to say how many times this feature appeared or disappeared in the subfamily.Note 2. In Cerapachys the abdominal segments III and IV are externally separated by at least a girdling constriction between pre- and postsclerites of segment IV. Additionally, abdominal segment III may be of various sizes, in some species offragosus and typhlus species-groups sensu Brown (1975) being much smaller and forming what can be called a postpetiole. The species-group discussed here is an exception, having a very weak impression between pre- and postsclerites IV. Illustrated description of this character throughout the Cerapachyinae was provided by Bolton (1990).Note 3. In the original description of C. sexspinus (Xu, 2000), the tibial spur condition is described as single pectinate on middle and hind tibiae. The true condition is different, as all the specimens examined possess one simple and one broadly pectinate spur on both middle and hind tibiae. Bolton (2003) lists the following character states for spur formula in Cerapachys: 2p, 2p; 2(1s, 1b-p), 2(1s, 1p); 1s-b, 1p; 1p, 1p. The formula 1p, 1p is the most common, occurring in, for example, the antennatus-group (containing the type species of the genus), the speciose dohertyi-cribrinodis species-group (sensu Brown 1975), and in most species with sides of petiole margined (the'Phyracaces lineage' of Brown [1975]). The spur formula 1s-b, 1p is characteristic for apparently arboreal species related to C. longitarsus (Mayr, 1879). The unique spur formula 2p, 2p is present in the aberrant crawleyi-group (see general discussion below).Note 4. Of the species examined here, at least eguchii, paradoxus, and sexspinus exhibit considerable range of body size among workers. Only one specimen of C. doryloides has been examined, so nothing can be said about its polymorphism. A polymorphic worker caste is also present in some apparently not related, hitherto undescribed Cerapachys (author's unpublished data). Due to a limited amount of material, quantitative analysis of allometry and polymorphism is not attempted here but there seems to be continuous size variation, and allometry of various body parts is weakly pronounced.No gynes or males are known thus far and the diagnosis is based solely on worker characters.