Adetomyrma venatrix

"The twenty-one workers were collected from the lower surface of a rotten log, at the log/soil interface, in a tract of tropical dry forest in western Madagascar. The workers appeared to be foraging as a group, much in the manner of several small Cerapachys species that are characteristic of the dry forest of western Madagascar, although it is possible that they were recruiting to a prey item (not seen). Unfortunately time did not permit a detailed search for the colony. One of the workers stung my finger and this produced a noticeable stinging sensation (and later a slight swelling that persisted for several days) despite the minute size of the worker. It seems reasonable to surmise that Adetomyrma ventrix is a specialized predator or ground-dwelling arthropods." Ward (1994)

Identification
Ward (1994): (i) absence of a petiole in dorsal view (abdominal tergum 3 lacking a dorsally differentiated pretergite), (ii) gaster large and expanded posteriorly, all terga and sterna unfused and without constrictions, (iii) absence of eyes, and (iv) presence of a very large sting (larger, in relation to body size, than that of any other known ant).

Distribution
This taxon is known only from Madagascar.

Habitat
Tropical forest - dry, montane and rainforest.

Abundance
Only known from a few collections.

Worker
Worker measurements (n = 13). HW 0.40-0.49, HL 0.48-0.56, SL 0.29-0.34, PW 0.28-0.33, DPW 0.20-0.27, LHT 0.32-0.37. CI 0.83-0.90, SI 0.66-0.73.

Description (worker ). Small (HW < 0.50mm), pale and blind. Mandibles subfalcate, without distinct basal and masticatory margins; inner margin with 3 or (more commonly) 4 teeth, equally spaced and lying in t h e same plane as the front of the head, followed by a gap (0.05-0.06mm) and two longer (subapical and apical) teeth which, as a consequence of the curvature of the mandibles, lie in the dorsoventral plane when the mandibles are closed. Closed mandibles with apices over- lapping. Clypeus very short, its principal surface deflected ventrally, anterior margin broadly convex and furnished with a row of about 20 small, specialized, conical setae. Frontal carinae short, low, expanded laterally as small frontal lobes that over n o more than about a third of t h e antennal insertions (dorsal view). Medial portion of the antennal sclerite (torulus) upturned and fusing with the frontal carinae. Scape notably shorter than head length (SL/HL 0.59-0.61); first funicular segment c. 2.3 times longer than broad, and approximately equal to the combined length of the next three funicular segments; funicular segments 2-8 broader than long, segments 8-11 becoming gradually enlarged but not forming a distinct club. Terminal funicular segment c. 2.5 times longer than penultimate segment, and about half the scape length. Head subquadrate, longer than wide (CI 0.83-0.90), widest near the mandibular insertions; sides slightly convex, converging posteriorly and rounding into the concave posterior margin. Mesosoma dorsum somewhat flattened in profile, lateral margins rounded; in dorsa1 view pro- notum longer than broad, with convex sides, mesonotum very short and twice as wide as long. Basal (= dorsal) face of propodeum narrower than pronotum, about 1.5 times longer than wide, with subparallel sides that converge slightly towards the mesonotum; basal face of propodeum about 2.5 times the length of the declivitous face, and rounding gently into the latter. Metapleuron fully fused with propodeum, the two not distinguishable in lateral view. Metapleural gland bulla conspicuous, manifested as a large circular patch on the lower posterolateral corner of the mesosoma, its dorso-ventral height about two-thirds the length of the declivitous face of the propodeurn. Inferior propodeal (‘metapleural’) lobes essentially undeveloped. Abdominal tergum 2 c. 1.4 times broader than long, in dorsal view. Abdominal sternum 2 with a conspicuous subpetiolar process, shaped like an irregular axe blade. Abdominal sternum 3 with anteroventral surface evenly convex, lacking protuberant ridges near the helcium.

Mandibles smooth with scattered punctures. Most of body smooth and shining; head and mesosoma dorsum with numerous piligerous punctures (c. 0.010-0.015 mm diameter) separated by one to several times their diameters, densest on the head (except for a smooth puncture- free median strip). A few scattered punctures on abdominal tergum 2, remainder of metasoma with small, less conspicuous punctulae, preceded on the exposed portions of the anterior margins of each sclerite by fine transverse reticulate-striolate sculpture. Sides of propodeum and metapleuron with weak reticulations. Body with a rather dense cover of pale, erect and suberect hairs; more than 30 standing hairs visible in profile on the mesosoma dorsum; anterior margin of clypeus with a row of long (up to 0.12 mm), slender, curved setae (dorsad of the specialized tooth-like setae) that exceed the closed mandibles; erect setae also present on the scapes, funiculi, and extensor surfaces of the tibiae. Colour: light yellow-brown, with narrow darker bands at the posterior margins of abdominal segments 2 to 4 or 5.

Queen
Undescribed.

Male
Undescribed.

Type Material
Holotype worker

Paratypes. Series of twenty workers, same data as holotype to be deposited in, , , , , , Phil Ward Collection,.

Type Locality Information
MADAGASCAR, Zombitse Forest, along Route Nationale 7, 15 km E Sakaraha, 760 m, 22“54’S, 44”41’E, 15 February 1993, P. S. Ward no.11932, ex rotten log, tropical dry forest

Additional References

 * Ward, P. S. 1994. Adetomyrma, an enigmatic new ant genus from Madagascar (Hymenoptera: Formicidae) and its implications for ant phylogeny. Systematic Entomology. 19:159-175.