Acropyga keira

Workers and males were collected from a nest in July, but otherwise nothing is known of its natural history.

Identification
From Lapolla (2004):

Diagnosis - Worker: 9 segmented antennae (but see description); mesosoma with short, appressed hairs, giving it a bare appearance; mandible with 3 teeth. Queen: unknown. Male: 11 segmented antennae; parameres roughly rectangular, covered in hairs of varying lengths, with thickest concentration toward the middle. Compare with Acropyga exsanguis and Acropyga romeo.

The short appressed hairs that cover A. keira are the main distinguishing characteristic of the worker. Nonetheless, A. keira workers can be difficult to distinguish from other members of the goeldii complex, especially from Acropyga exsanguis workers. A. keira has very few erect to suberect hairs on the mesosoma, and when present they are only found on the posterior region of the pronotum, whereas A. exsanguis always has abundant erect to suberect hairs on the mesosoma. The head of A. keira is also typically longer than broad, while in A. exsanguis the head is typically broader or at least as broad as long.

The best way to confirm A. keira is with male specimens, which are very distinct from A. exsanguis and other closely related species. The penis valve of A. keira is unique in that it is shorter (as measured from apodeme to caudal tip) than other goeldii complex members, and the laterally expanded, flattened tips are distinctly large relative to the whole structure.

Key to New World Acropyga Workers / Males

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica.

This species is known only from its type locality in Costa Rica.

Nomenclature

 *  keira. Acropyga keira LaPolla, 2004a: 53, figs. 21, 39, 45 (w.m.) COSTA RICA.

Worker
Head: yellow; head longer than broad; covered in layer of short appressed hairs; posterior margin slightly concave; 9 segmented, incrassate antennae (note that males have 11 segments suggesting workers could have up to 10 segments); scape reaches or fails to reach posterior margin by about half length of pedicel; clypeus narrow, convex and covered in thick layer of suberect to erect hairs of varying lengths; mandible with 3 teeth; gap exists between anterior clypeal margin and inner mandibular margin. Mesosoma: yellow; pronotum in lateral view rises steeply toward mesonotum; covered in thin layer of short appressed hairs, except along posterior end where several erect hairs are present; mesonotum nearly at level of propodeum, covered in layer of short appressed hairs; metanotal area distinct; propodeum with layer of short appressed hairs; declivity steep. Gaster: petiole thick and erect; gaster yellow; covered in appressed hairs, with scattered erect hairs throughout, especially along posterior segmental margins.

Measurements (n=4): TL: 2. 14-2.23; HW: 0.491-0.513; HL: 0.532-0.543; SL: 0.39-0.413; ML: 0.588-0.609; GL: 1.02-1.1; CI: 90.9-95.5; SI: 76.8-82.1.

Queen
Queens are not known for this species.

Male
Head: brownish-yellow, darker toward apex around 3 prominent ocelli; head about as broad as long; posterior margin broadly rounded, with rounded posterolateral comers; eyes large, breaking outline of head in full frontal view; 11 segmented antennae; scape surpasses posterior margin by about half length of pedicel; clypeus slightly convex, covered in a dense layer of suberect to erect hairs; mandible typically with 2 teeth separated by a diastema; occasionally a small tooth develops near apical tooth, making mandible 3-toothed; a gap exists between anterior clypeal margin and inner mandibular margin. Mesosoma: yellow; pronotum collar-like, overarched by mesonotum, which is rounded anteriorly; mesonotum flat covered with layer of short appressed hairs; propodeum broadly rounded into an indistinct declivity. Gaster: petiole thick and erect; gaster yellow; covered in layer of short appressed hairs. Genitalia: parameres rectangular, coming to a point dorsocaudally; parameres mostly covered in layer of hairs of varying lengths, longest near middle of parameres, and then parameres bare toward base; cuspi cylindrical, bending toward apices with a number of short, peg-like teeth; digiti anvil-shaped, bent toward cuspi, meeting them dorsally, where there are a series of short peg-like teeth.

Measurements (n=2): TL: 1.93-2.09; HW: 0.369-0.378; HL: 0.406-0.407; SL: 0.35-0.354; ML: 0.624-0.741; GL: 0.901-0.947; CI: 90.9-93.0; SI: 92.6-95.9

Type Material
Holotype worker, COSTA RICA: Heredia, La Selva Biological Station, elev. 50-150 m, 10026' N, 840 I' W (J. Longino) (INBC); 1 paratype worker, 1 paratype male, same locality as holotype (MCZC). The holotype is labeled JSL TYPE # 102.

Etymology
The specific epithet keira is Greek for cut short, in reference to the distinctly short hairs that are found on the head and mesosoma.