Yunodorylus

This is a poorly known genus with striking morphology somewhat reminiscent of Dorylus. Very little is known about this lineage. Yunodorylus eguchii nests in soil in evergreen forests and dry dwarf forests in southern Vietnam. A colony sample (type series) of Y. eguchii contained larvae of various sizes. (Borowiec 2016)

Identification
Borowiec (2016) - Worker Workers of Yunodorylus are stout ants with no eyes and body coloration ranging from yellow to reddish, with cuticle sculpture and pilosity moderate. Yunodorylus is the only non-army ant doryline with a single waist segment and no or very weak girdling constriction on abdominal segment IV. It can be distinguished from army ant dorylines by relatively high positioned propodeal spiracle and presence of propodeal lobes. Male The males of Yunodorylus have a distinctive habitus with abdominal segment III very broadly attached posteriorly to segment IV and gaster widest towards the apex, posterior of abdominal segment IV. A combination of propodeal lobes well-developed, 13-segmented antennae, helcium relatively narrow and axial, no constrictions between abdominal segments IV, V, and VI, and wings always with veins C, R·f3, and at least a stub of Rs·f2–3 will distinguish Yunodorylus males from other genera. Although there may be gutter-like constrictions on abdominal segment IV and beyond, these are restricted to the tergites and do not produce constricted appearance in lateral view as in, for example, Zasphinctus. Sharp and conspicuously ventrally hooked penisvalvae appear to be unique among dorylines.

Distribution
Restricted to mainland Southeast Asia and Borneo, although it is possible it will be eventually found on other islands (Borowiec 2016).

Fossils
Fossils are known from: (an unidentified species, Wang et al., 2021).

Castes
Eguchi et al. 2016 - The “full-dichthadiigyne” in Dorylinae is usually defined by a combination of the following characteristics: compound eyes vestigial or absent; head swollen and subglobular, often with falcate mandibles; mesosoma without flight sclerites; petiole hypertrophied, commonly bilaterally cornulate; gaster distended (Bolton, 1990; Hölldobler & Wilson, 1990; Gotwald, 1995). Thus, it is safe to conclude that the queen of Y. eguchii is subdichthadiiform, based on: head less swollen and not subglobular; mandibles triangular (as seen in the worker); petiole less hypertrophied and simple in shape. In other words, the worker-queen dimorphism is weaker in Yunodorylus than in the Dorylinae lineages with a full dichthadiigyne. The remarkable differences between the worker and queen in Yunodorylus are body proportions, presence (worker) or absence (queen) of metatibial gland, and presence (worker) or absence (queen) of pygidial peg-like or spine-like setae. Interestingly, the absence of pygidial peg-like or spine-like setae is also known in the normal and subdichthadiiform queens of the genus Acanthostichus (Brown, 1975; Mackay, 2004).

Nomenclature

 *  YUNODORYLUS  [Dorylinae]
 * Yunodorylus Xu, 2000b: 297. Type-species: Yunodorylus sexspinus, by original designation.
 * Yunodorylus junior synonym of Cerapachys: Bolton, 2003: 141, 268.
 * Yunodorylus as genus: Borowiec, 2016: 232.

Taxonomic Notes
Borowiec (2016) - The genus was originally established for Yunodorylus sexspinus by Xu (2000) from Yunnan, China and synonymized by Bolton (2003) under Cerapachys. In a recent contribution I provided descriptions and a key (Cerapachys sexspinus species group and Key to Yunodorylus) to the four species so far known from workers (Borowiec 2009). Based on genomic data, Yunodorylus is part of a well-supported clade also including Cerapachys and Chrysapace.

Worker
Borowiec (2016) - Head: Antennae with 11 or 12 segments. Apical antennal segment not enlarged, not broader and longer than two preceding segments combined. Clypeus without cuticular apron. Lateroclypeal teeth present. Parafrontal ridges absent or reduced. Torulo-posttorular complex vertical. Antennal scrobes absent. Labrum with median notch or concavity. Proximal face of stipes projecting beyond inner margin of sclerite, concealing prementum when mouthparts fully closed. Maxillary palps 2-segmented. Labial palps 2-segmented. Mandibles triangular, with teeth or falcate, with teeth on elongated masticatory margin. Eyes absent. Ocelli absent. Head capsule with differentiated vertical posterior surface above occipital foramen. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Posterior head corners dorsolaterally immarginate. Carina surrounding occipital foramen ventrally absent. Mesosoma: Pronotal flange not separated from collar by distinct ridge. Promesonotal connection with suture completely fused. Pronotomesopleural suture visible, unfused partway to notal surface. Mesometapleural groove weakly impressed. Transverse groove dividing mesopleuron absent. Pleural endophragmal pit concavity present. Mesosoma dorsolaterally immarginate. Metanotal depression or groove on mesosoma absent. Propodeal spiracle situated low on sclerite. Propodeal declivity without distinct dorsal edge or margin and rectangular in posterior view. Metapleural gland with bulla visible through cuticle. Propodeal lobes present, short. Metasoma: Petiole anterodorsally, dorsolaterally immarginate, and laterally above spiracle immarginate. Helcium in relation to tergosternal suture placed at posttergite and axial or supraaxial. Prora forming a vertical carina. Spiracle openings of abdominal segments IV–VI circular. Abdominal segment III anterodorsally immarginate and dorsolaterally immarginate. Abdominal segment III more than half size of succeeding segment IV, which is weakly constricted at presegmental portion (uninodal waist). Girdling constriction of segment IV absent, i.e. pre- and postsclerites indistinct. Cinctus of abdominal segment IV not impressed. Abdominal segment IV not conspicuously largest segment. Abdominal tergite IV not folding over sternite, and anterior portions of sternite and tergite equally well visible in lateral view. Girdling constriction between pre- and posttergites of abdominal segments V and VI absent. Girdling constriction between pre- and poststernites of abdominal segments V and VI absent. Pygidium medium-sized, with impressed medial field, and armed with cuticular spines. Hypopygium unarmed. Legs: Mid tibia with pectinate and simple spur. Hind tibia with pectinate and simple spur. Hind basitarsus not widening distally, circular in cross-section. Posterior flange of hind coxa not produced as raised lamella. Metatibial gland present as oval patch of whitish cuticle. Metabasitarsal gland absent. Hind pretarsal claws simple. Polymorphism: Monomorphic to moderately polymorphic.

Male
Borowiec (2016) - Head: Antennae with 13 segments. Clypeus with cuticular apron. Parafrontal ridges absent. Torulo-posttorular complex vertical. Maxillary palps 3-segmented. Labial palps 2-segmented. Mandibles triangular, edentate to falcate. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Carina surrounding occipital foramen ventrally absent. Mesosoma: Pronotal flange not separated from collar by distinct ridge. Notauli absent. Transverse groove dividing mesopleuron absent or present. Propodeal declivity reduced, without distinct dorsal edge or margin. Metapleural gland opening absent or present. Propodeal lobes present. Metasoma: Petiole anterodorsally immarginate, dorsolaterally immarginate, and laterally above spiracle immarginate or marginate. Helcium in relation to tergosternal suture placed at posttergite and axial. Prora forming a simple U-shaped margin. Spiracle openings of abdominal segments IV–VI circular. Abdominal segment III more than half size of succeeding segment IV; latter weakly constricted at presegmental portion (uninodal waist). Girdling constriction of segment IV present, i.e. pre- and postsclerites distinct. Cinctus of abdominal segment IV gutter-like, not sculptured. Girdling constriction between pre- and postsclerites of abdominal segments V and VI absent. Abdominal segment IV not conspicuously largest segment. Abdominal sternite VII simple. Abdominal sternite IX distally armed with two spines, with lateral apodemes about as long as medial apodeme, directed anteriorly (towards head). Genitalia: Cupula short relative to rest of genital capsule and shorter ventrally than dorsally. Basimere broadly fused to telomere, with no sulcus trace at junction, and ventrally with left and right arms abutting. Telomere gradually tapering toward apex. Volsella gradually tapering toward apex. Penisvalva hook-like, strongly curved ventrally. Legs: Mid tibia with single pectinate spur. Hind tibia with single pectinate spur. Posterior flange of hind coxa not produced as raised lamella. Metatibial gland absent. Metabasitarsal glands absent. Hind pretarsal claws simple. Wings: Tegula present, broad, demiovate in shape. Vein C in fore wing present. Pterostigma broad. Abscissa R·f3 present and running toward distal wing margin and enclosing cell with Rs·f5 or not. Abscissae Rs·f2–3 present, disconnected from Rs+M, rarely closely approaching Rs+M. Cross-vein 2r-rs present, connected to Rs·f2–3&Rsf4. Abscissae Rs·f4–5 present, fused in absence of 2rs-m. Abscissa M·f2 in fore wing contiguous with Rs+M. Abscissa M·f4 in fore wing present, reaching wing margin. Cross-vein 1m-cu in fore wing present. Cross-vein cu-a in fore wing present, arising from M+Cu and proximal to M·f1. Vein Cu in fore wing present, with only Cu1 branch prominent. Vein A in fore wing with abscissae A·f1 and A·f2 present. Vein C in hind wing absent. Vein R in hind wing absent. Vein Sc+R in hind wing present. Abscissa Rs·f1 in hind wing present, shorter than 1rs-m. Abscissa Rs·f2 in hind wing present, not reaching wing margin. Cross-vein 1rs-m in hind wing present, about as long as M·f1. Vein M+Cu in hind wing present. Abscissa M·f1 in hind wing present. Abscissa M·f2 in hind wing present. Cross-vein cu-a in hind wing absent. Vein Cu in hind wing present. Vein A in hind wing with abscissa A·f1 present.