Acanthostichus bentoni

The type specimens were collected early in the morning in the reserve belonging to the Biological Dynamics of Forest Fragments Project (Smithsonian Institution / World Wildlife / Instituto Nacional de Pesquisas da Amazonia (INPA) Collaborative Project). This reserve is a very large patch of continuous forest and is often referred to by the project participants as “41” reserve (Benton. pers. comm.). Dr. Benton observed a short trail (at most about 1 m long) at night, emerging from a hole in sandy soil in a forest clearing in which the main camp site of the “41” reserve is situated. At the end of the trail the ants were feeding on small pieces of cut earthworm. Dr. Benton was not certain the ants had killed the earthworm or were merely opportunist scavengers. (Mackay 1996)

Identification
Mackay (1996) - This species could be confused with Acanthostichus lattkei. It can be easily separated based on three good characters: the anterior half of the head is finely striate or costulate (anterior fourth of head of A. lattkei is similar, but more finely sculptured), the anterior medial tooth of clypeus is absent (present in A. lattkei and the medial border is strongly and deeply excised (Fig. 7), and the top of the petiole is fmally punctate (lightly longitudinally striate in A. lattkei. The petiole is not quadrate with carinae on the lateral edges as in A. quadratus. It differs from A. serratulus as there are no carinae on the lateral edges of the petiole. The excised clypeal border easily separates it from workers of essentially all other species.

Distribution
Mate Grosso, Brazil

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Castes
Known only from the worker caste.

Nomenclature

 *  bentoni. Acanthostichus bentoni Mackay, W.P., 1996: 143, fig. 7 (w.) BRAZIL.

Worker
Worker (holotype in parentheses): HL (1.10)-1.14, HW (l.06)-1.14, SL (0.61)-0.64, EL 0.03-(0.05), WL (1.48)-1.58, PW (0.53)-0.54, PL (0.45)-0.53, SI 56 (56), CI (97)-100, PI (86)-98, SL/SW (3.20)-3.47.

Mandibles toothless, apex pointed; anterior border of clypeus strongly excised between bases of frontal carinae (Fig. 7), lateral teeth moderately well formed (Fig. 7); head slightly narrowed posteriorly; vertex slightly, but broadly concave; eyes small, 4-6 poorly defined ommatidia; scape with concave anterior border, not unusually thickened; mesosoma as in others in the species complex; propodeum concave posteriorly, poorly defined tubercles on each comer, united with a weakly defined carina; petiole wider than long, anterior face strongly concave, subpetiolar process large with posteriorly directed point, as others in the complex; gaster as in other species. Sculpture mostly smooth and polished, except the anterior half of the head is rough and costulate, dorsum of petiole finely punctate. Hairs long (over 0.5mm), erect, golden, abundant on most surfaces; decumbent pubescence lacking. Reddish brown, gaster somewhat lighter in color.

Type Material
Type series. Brazil. Amazonas. ZF3. Km41. Res. 41 WWF. 7-viii-1991. F. Benton leg. Holotype worker and two paratype workers. Forbes Benton gave additional specimens from the series to Barry Bolton, which are presumably in the British Museum. The series was collected in Reserve 1501 at km 41 of the ZF-3 road which joins the BR 174 Boa Vista - Manaus Highway at km 64 (64 km N Manaus).

Etymology
Named in honor of the collector of the type specimens. Dr. Forbes Benton. The specimens were forwarded to me by Dr. Ana Harada.