Eburopone, Borowiec, Marek L., 2016

Borowiec, Marek L., 2016, Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae), ZooKeys 608, pp. 1-280 : 107-110

Taxon classification Animalia Hymenoptera Formicidae

Eburopone gen. n.

Type-species.

Cerapachys wroughtoni , by present designation.

Only one species of this group has been described from Afrotropics, but Madagascar harbors a considerable undescribed diversity.

Diagnosis.

Worker. Workers of Eburopone are most easily recognized from other dorylines by a unique whitish patch of cuticle of presumably glandular function present on the posterior edge of abdominal sternite IV, although the patch may be faint in small or pale-colored specimens. A combination of 12-segmented antennae, propodeal spiracle placed low on the sclerite and propodeal lobes present, petiole dorsolaterally immarginate, lack of conspicuous constrictions posterior to abdominal segment IV, helcium narrow and placed at about mid-height of the segment, pronotomesopleural Pronotomesopleural suture present, and mid and hind tibiae each with a single pectinate spur will serve to distinguish Eburopone workers from other dorylines. In the Afrotropics and in Madagascar other non-army dorylines include Ooceraea , Parasyscia , Lividopone , Lioponera , and Zasphinctus . None of these genera possesses the characteristic, apparently glandular, patch on the underside of gaster, but if that character is not obvious or obscured, it is still relatively easy to distinguish Eburopone : Ooceraea found in this region ( Ooceraea biroi ) have 9-segmented antennae, Parasyscia and Lividopone have pronotomesopleural sutures fused, and Lioponera has a dorsolaterally marginate petiole and a raised flange on hind coxa. Zasphinctus belongs to the genera with pronounced constrictions between abdominal segments IV, V, and VI.

Male. The male morphology of Eburopone is very variable, including wing venation, but the following combination of characters usually allows separation from other genera: Antennae with 13 segments, at least weak constriction present anterior to abdominal segment IV, costal vein (C) present in the fore wing, submarginal cell open, presence of R·f3 and a free 'stigmal vein’ formed by 2r-rs and Rs·f4-5 in the absence of Rs·f2-3 or 2rs-m, not running to the wing margin. Among non-army ant dorylines that overlap in range with Eburopone , Lioponera and Ooceraea can have a free stigmal vein but these genera never have costal vein running along the anterior margin of the fore wing in combination with R·f3 present past pterostigma.

Description.

Worker.Head: Antennae with 12 segments. Apical antennal segment moderately enlarged, broader than and about equal in length to two preceding segments combined to conspicuously enlarged, much broader than and longer than two preceding segments combined. Clypeus without cuticular apron. Lateroclypeal teeth present. Parafrontal ridges 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, edentate. Eyes absent or present, composed of at most several weakly differentiated ommatidia. 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 present. Mesosoma: Pronotal flange often separated from collar by ridge, usually distinct but rarely poorly developed or absent. Promesonotal connection with Pronotomesopleural suture present, weakly differentiated or with Pronotomesopleural suture conspicuous and complete but immobile. Pronotomesopleural suture visible as groove but not unfused. Mesometapleural groove deeply impressed, conspicuous. Transverse groove dividing mesopleuron present. Pleural endophragmal pit concavity present. Mesosoma dorsolaterally immarginate. Metanotal depression or groove on mesosoma absent. Propodeal spiracle situated low on sclerite. Propodeal declivity with distinct dorsal edge or margin and rectangular in posterior view. Metapleural gland usually with bulla visible through cuticle, sometimes obscured. Propodeal lobes present, well developed. Metasoma: Petiole anterodorsally immarginate or marginate, dorsolaterally immarginate, and laterally above spiracle marginate. Helcium in relation to tergosternal Pronotomesopleural suture placed at posttergite and axial. Prora forming a U-shaped margin with median ridge. 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). Abdominal segment III about half size of succeeding segment IV, which is strongly constricted at presegmental portion (binodal waist). Girdling constriction of segment IV present, i.e. pre- and postsclerites distinct. Cinctus of abdominal segment IV gutter-like and cross-ribbed; sculpturing may be weak. Abdominal segment IV not conspicuously largest segment. Abdominal segment IV 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 large, with impressed medial field, and armed with modified setae. Hypopygium unarmed. Legs: Mid tibia with single pectinate spur. Hind tibia with sin gle pectinate 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.

Male.Head: Antennae with 13 segments. Clypeus with or without cuticular apron. Parafrontal ridges absent. Torulo-posttorular complex vertical. Maxillary palps 4- or 3-segmented. Labial palps 3- or 2-segmented. Mandibles triangular with teeth or falcate. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Carina surrounding occipital foramen ventrally absent or present. Mesosoma: Pronotal flange not separated from collar by distinct ridge. Notauli present at least anteriorly, very rarely absent. Transverse groove dividing mesopleuron absent or present. Propodeal declivity reduced, without distinct dorsal edge or margin. Metapleural gland opening absent. Propodeal lobes present. Metasoma: Petiole anterodorsally immarginate or marginate, dorsolaterally immarginate, and laterally above spiracle immarginate. Helcium in relation to tergosternal Pronotomesopleural suture placed at posttergite and axial. Prora simple, not delimited by carina. 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 long relative to rest of genital capsule and of approximately equal length on both dorsal and ventral surfaces. Basimere broadly fused to telomere, with no sulcus trace at junction, and ventrally with left and right arms abutting. Telomere not apically expanded, very reduced relative to basimere. Volsella variable. Penisvalva laterally compressed, rounded at apex. 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 present as oval patch of whitish cuticle. 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 but not enclosing cell with Rs·f5 or rarely absent. Abscissae Rs·f2-3 absent. Cross-vein 2r-rs present, forming base of 'free stigmal vein’ (2r-rs&Rs·f4-5) in absence of Rs·f3 and 2rs-m or rarely absent. Abscissae Rs·f4-5 fused in absence of 2rs-m or rarely absent. Abscissa M·f2 in fore wing contiguous with Rs+M or rarely absent. Abscissa M·f4 in fore wing present, reaching wing margin or not, rarely entirely absent. Cross-vein 1m-cu in fore wing present or rarely absent. Cross-vein cu-a in fore wing present, arising from M+Cu and proximal or near M·f1. Vein Cu in fore wing present, with only Cu1 branch prominent or absent past M+Cu. Vein A in fore wing with abscissae A·f1 and A·f2 or only A·f1 present. Vein C in hind wing absent. Vein R in hind wing present, extending past Sc+R but not reaching distal wing margin. Vein Sc +R in hind wing absent or present. Abscissa Rs·f1 in hind wing present, shorter than 1rs-m. Abscissa Rs·f2 in hind wing absent or present, not reaching wing margin. Cross-vein 1rs-m in hind wing fused with M·f1 or absent. Vein M+Cu in hind wing absent or present. Abscissa M·f1 in hind wing absent or present. Abscissa M·f2 in hind wing absent. Cross-vein cu-a in hind wing absent or present. Vein Cu in hind wing absent or present. Vein A in hind wing present with abscissa A·f1 present or absent.

Gyne. At least one dealate gyne specimen with fully developed wing sclerites is known, but ergatoid queens have also been collected (Peter Hawkes pers. comm.).

Larva. Larvae have not been described. Cocoons present.

Distribution.

One species of Eburopone , Eburopone wroughtoni , has been described so far from South Africa and Zimbabwe, but more species are evidently to be found throughout Sub-Saharan Africa, as evidenced by unassociated males and gynes present in collections. Specimens belonging to this group have also been collected in Cameroon and Mozambique, suggesting that Eburopone is widely distributed in Africa. This lineage is also represented by a major radiation in Madagascar with dozens of species, none of which has been described.

Taxonomy and phylogeny.

Cerapachys wroughtoni was originally described by Forel from South Africa and the same author subsequently described Cerapachys wroughtoni var. rhodesiana and Cerapachys roberti , both considered junior synonyms of wroughtoni by Brown (1975).

The position of Eburopone on the doryline tree is uncertain ( Brady et al. 2014, Borowiec, in prep.) and the internal phylogeny of the group has never been investigated in detail, although it appears that the Madagascar species are nested within Afrotropical lineages and that the crown group of this genus is very old (Borowiec, in prep.).

Biology.

There are no published reports on the biology of this lineage, although field observations suggest that most species are subterranean, have relatively populous colonies, and forage on brood of other ants. Based on several nest samples of undescribed Malagasy species where only larvae or pupae were collected, brood production appears to be synchronized (Brian Fisher pers. comm., author’s observations).

Species of Eburopone

Eburopone wroughtoni (Forel, 1910c): South Africa, comb. n.