Asphinctopone pilosa

The single known specimen of this species was collected in a forest area, in an accumulation of moist leaf litter at the base of a large sloping rock outcrop. This microhabitat was a moister and thicker litter layer than was typical for the location. (Hawkes, 2010)

Identification
From Hawkes 2010: "Asphinctopone pilosa is distinctly different from its congeners in many respects; the most obvious differences are 1) its larger size, 2) the stronger and much more extensive sculpturation and denser pubescence, 3) the differently shaped mesonotum and propodeum, 4) the far less strongly impressed promesonotal suture and metanotal groove, 5) the terminal four, rather than three, antennal segments forming a weak club, 6) the more strongly squamiform petiole, which is also more arcuate in dorsal view, 7) the less developed clypeal structure (in Asphinctopone silvestrii and Asphinctopone differens the median clypeal lobe is bounded by distinct sharp angles, is distinctly though shallowly concave on either side of the more acutely rounded median projection and is relatively broader at about 0.40 x HW), 8) the lack of a tooth-like process on the inner basal margin of the mandible and 9) its darker colour.

Distribution based on Regional Taxon Lists
Afrotropical Region: United Republic of Tanzania.

Biology
Asphinctopone is one of the most rarely collected and least known small ponerine genera of the Afrotropical region. Specimens are seldom found and most samples recovered consist of only one or two workers. As a measure of its rarity, a survey of leaf litter in Ghana (Belshaw & Bolton, 1994) recorded 43,824 individual ants, of which only 5 (about 0.01%) were Asphinctopone. Despite this rarity, the genus is widespread in wet forest zones in leaf litter, topsoil, pieces of rotten wood and rotting vegetation on the forest floor. One worker has been found foraging in a fallen, abandoned termitary (Dejean et al., 1996). Beyond this nothing is known of its biology. Its specialised morphology implies that it may be prey-specific, but in reality its victims remain unknown. (Bolton and Fisher 2008)

Nomenclature

 *  pilosa. Asphinctopone pilosa Hawkes, 2010: 29, figs. 1A-E (w.) TANZANIA.

Description
Holotype worker. TL 4.48, HL 1.07, HW 0.86, CI 81, SL 0.80, SI 92, OD 0.06, OI 7, PW 0.66, WL 1.38 (all measurements in mm).

Medium sized (total length c. 4.5 mm) ponerine ant largely conforming to the diagnosis of the genus as presented by Bolton & Fisher (2008), but with differences in the development of the promesonotal and metanotal grooves, antennal structure and median clypeal lobe as indicated below. Mandibles smooth and shining, without any sculpture other than coarse scattered hair-pits and with five teeth plus a small denticle between the basal and the second tooth. No tooth-like process on the inner basal margin of the mandible. Eyes very small, comprising a single central ommatidium surrounded by a ring of 6 less distinct ommatidia, positioned distinctly in front of the mid-length of the sides of the head. Ocular diameter less than half the maximum width of the antennal scape. Entire dorsum, sides and ventral surfaces of head with quite coarse punctures (up to 0.03 mm diameter) with weak irregular sculpture between the punctures on the dorsal and dorso-lateral surfaces. Median portion of the vertex, as well as the sides of the head below the eyes, with larger and more widely spaced punctures. Pubescence on head dense, decumbent and arising both from within the numerous large punctures and from minute hair-pits between these, more sparse on the sides of the head below the eye and on the underside, giving these areas a smoother and more polished appearance. Frontal lobes somewhat more densely and more finely punctulate than remainder of the head; frontal carinae and antennal scrobes absent. In full-face view the sides and the posterior margin of the head very shallowly convex. Antennal scapes when laid back just reaching the occipital margin. Funicular segments 2–10 broader than long, segments 2–7 very distinctly so. Funicular segments 8–11 broader than the preceding 6, becoming increasingly longer relative to their width and forming an indistinctly 4-segmented club. The terminal funicular segment much longer than broad and distinctly exceeding the combined length of the preceding 5 segments. Clypeus with a projecting median lobe bounded by a rounded obtuse angle on each side, the anterior margin of this lobe flat to very slightly concave laterally and with a broadly rounded median projection. Width of the anterior margin of the projecting clypeal lobe about 0.33 x HW. Several pairs of strong setae and a number of weaker setae present on the clypeus.

Mesosoma with a pattern of sculpturing very similar to that of the head; dorsum and sides of pronotum, mesonotum and propodeum entirely coarsely punctulate and covered with a dense pelt of fine suberect (pronotum and mesonotum) to erect (propodeum) curved pubescence, the katepisternum and the disc of the pronotum with more sparse punctures and pilosity. Ventral surfaces of the mesosoma with dense fine puncturation and reduced pubescence. The punctulate sculpture on the dorsal and lateral mesosoma is overlaid by irregular effaced fine rugulose sculpture everywhere except on the disc of the pronotum and small areas of the lower propleuron and katepisternum. Pronotal humeri broadly rounded; the pronotum with a subglobose appearance in dorsal view. Promesonotal suture moderately impressed and with cross-ribs on the anterior mesonotum, the metanotal groove only slightly impressed and with fewer more widely spaced but much longer cross-ribs. Mesonotum twice as wide as long. Propodeal dorsum narrow, about half the width of the mesonotum and extending horizontally from the level of the metanotal groove to the short upper portion of the declivity, which slopes downward at about 45o to the junction with the very steep main face of the declivity. The propodeal outline thus presents three distinct planes in profile view. Propodeal dorsum about 1.5 x as long as the mesonotum. Declivity of the propodeum the only portion of the dorsal mesosoma lacking sculpture and with greatly reduced pilosity; smooth and weakly shining.

Petiole node high and squamiform, unsculptured apart from minute hair-pits, smooth and weakly shining and with pubescence similar to but less dense than that on the mesosoma. In profile view the anterior and posterior faces of the petiole node almost parallel, only slightly convergent dorsally; in posterior view the dorsal margin forming a bluntly triangular peak. In dorsal view the anterior face shallowly convex, the posterior even more shallowly concave. Subpetiolar process with the complex shape characteristic of the genus.

Gaster unsculptured apart from minute hair-pits (c. 0.005 mm diameter), pubescence denser but shorter (0.04 mm) on tergites 2–4 than on the first gastral tergite (0.07 mm), much longer and more variable on the sternites. No setae present on gastral tergites 1–4, but a few pairs on each sternite and abundant setae present on the pygidium and hypopygium. Sting stout and slightly upcurved in lateral view, somewhat laterally flattened.

A single (pectinate) spur is present on each tibia, those on the metatibiae much longer (0.34 mm) than those on the mesotibiae (0.17 mm), with those on the protibiae intermediate in length (0.29 mm). All segments of the appendages, including the antennae, with fine appressed pubescence but no standing hairs.

Colour: head and mesosoma dark reddish-brown throughout, the gaster, appendages and mandibles a lighter reddish-brown, with the exception of a small yellowish-brown patch on each mandible.

Type Locality Informtion
Tanzania, Tanga Region, Kilindi Forest Reserve, 1015 m,, 28.viii.2005, CEPF-TZ-3.4.F34, SAM-HYM-C020683, Primary forest, hand collected (P. Hawkes, J. Makwati, R. Mtana) (SAMC).

Etymology
The specific epithet pilosa refers to the pubescence which is much denser on the head and mesosoma than in all previously described species of the genus.

References based on Global Ant Biodiversity Informatics

 * Hawkes, P. G. "A new species of Asphinctopone (Hymenoptera: Formicidae: Ponerinae) from Tanzania." Zootaxa 2480 (2010): 27-36.