Acropyga tricuspis

This species is only known from two localities in Brazil.

Identification
From Lapolla (2004):

Diagnosis - Worker: 11 segmented antennae; mandible with an enlarged, square-shaped basal tooth with three distinct cusps. Queen: as in worker except for modifications expected for caste. Male: 12 segmented antennae; basal tooth as in worker, though less distinct. This species is unique in its appearance.

This species is easy to recognize with its distinctively enlarged, roughly square basal tooth with 3 discernible cusps. The enlarged basal tooth of A. tricuspis is interesting because unlike species of the Old World butteli species-group and the New World Acropyga panamensis, the enlarged basal tooth is square in shape rather than rectangular. An enlarged basal tooth has evolved independently at least 3 times within the genus, and in the New World the two species recorded with an enlarged basal tooth are not closely related to each other. A. tricuspis is most closely related to Acropyga donisthorpei (see there for further discussion).

Key to New World Acropyga Workers / Queens / Males

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Biology
Acropyga tricuspis has been collected in rainforest from leaf litter and rotten wood, but otherwise nothing is known of its natural history.

Nomenclature

 *  tricuspis. Acropyga tricuspis LaPolla, 2004a: 59, figs. 23, 40, 45 (w.q.m.) BRAZIL.

Worker
Head: brownish-yellow; head oval, rounded at posterolateral corners; head longer than broad; covered in a layer of short appressed hairs; posterior margin slightly concave; 11 segmented, incrassate antennae, with apical segment about as long as the four preceding segments; scape fails to reach posterior margin by about the length of the first two funicular segments; clypeus medially convex with longer erect hairs on surface; mandibles short and thick with 3 teeth; basal tooth enlarged and roughly square with 3 distinct cusps, first and second cusps comparatively smaller than the third cusp which is offset by a short diastema; inner mandibular margin and anterior clypeal margin nearly parallel. Mesosoma: brownish-yellow; pronotum in lateral view with a short anterior shelf that rises steeply toward mesonotum; posterior portion of pronotum with several long, erect hairs; mesonotum slightly elevated above level of propodeum, covered with layer of appressed hairs and sub erect to erect hairs; metanotal area distinct; propodeum with steep declivity. Gaster: petiole thick and erect; gaster brownish-yellow, covered in thick layer of appressed hairs with scattered suberect hairs.

Measurements (n=4): TL: 1.82-1.96; HW: 0.476-0.48; HL: 0.516-0.562; SL: 0.302-0.334; ML: 0.503-0.522; GL: 0.752-0.933; CI: 83.63-93.02; SI: 64.25-70.17.

Queen
As in worker except for modifications expected for caste.

Measurements (n=3): TL: 2.8-2.91; HW: 0.538-0.59; HL: 0.587-0.62; SL: 0.438-0.474; ML: 0.886-0.906; GL: 1.28-1.43; CI: 91.65-96.41; SI: 77.97-82.87.

Male
Head: brownish-yellow, darker toward apex around 3 prominent ocelli; head narrows toward apex; entire head covered in a fine layer of appressed hairs; 12 segmented antennae; scape reaches to posterior margin; clypeus slightly convex with several long erect hairs on surface; mandible short and thick with two teeth, the basal tooth as in workers and queens, except cusps are less well-defined. Mesosoma: brownish-yellow; pronotum small and collar-like, overarched by mesonotum; mesonotum rounded anteriorly, dorsum flat and covered in a thick layer of appressed hairs; propodeum flat, sloping gently toward declivity; declivity very short and indistinct. Gaster: petiole thick and erect; gaster brownish-yellow; covered in thick layer of appressed hairs with scattered suberect to erect hairs. Genitalia: parameres taper to rounded apices; parameres with numerous long hairs, becoming more numerous toward apices; cuspi taper to pointed apices, giving them a tubular appearance in ventral view; cuspi meets digiti dorsally; digiti anvil-shaped and flat.

Measurements (n=2): TL: 1.89-1.90; HW: 0.382-0.392; HL: 0.42-0.448; SL: 0.342-0.346; ML: 0.704-0.728; GL: 0.72-0.762; CI: 87.5-90.95; SI: 87.24-90.58.

Type Material
Holotype worker, BRAZIL: Amazonas, Ponta Negra; N. of Manaus; M-163 (W.L. Brown) (MCZC); 2 paratype workers, 2 paratype queens, 1 paratype male (MCZC). The holotype is labeled JSL TYPE # 103.

Etymology
The specific epithet tricuspis is Latin for three points, in reference to the three cusps found on the enlarged basal tooth.