Acropyga smithii

This species is the first recorded Acropyga species being transported by man (from Belize to Alabama presumably by ship: information from label data).

Identification
From Lapolla (2004):

Diagnosis - Worker: 7-8 segmented antennae; mandibles broad with 4 distinct teeth; mesosomal dorsum relatively flat (pronotum and mesonotum at about same height); an especially small species (total length < l.7 mm). Queen: as in worker with modifications expected for caste. Male: 9 segmented antennae; head longer than broad; in lateral view, parameres slightly tapering to a rounded apex; cuspi short meeting digiti dorsally. Compare with: Acropyga exsanguis, Acropyga fuhrmanni, and Acropyga stenotes.

This is among the smallest New World species (TL: 1.2-1.6); Acropyga panamensis is around the same size, though it is quite different morphologically from A. smithii. A. smithii workers can possess antennal segment counts as low as 7 segments, the lowest number observed in a New World Acropyga (the only other species to have antennal segment counts this low is Acropyga oceanica from Southeastern Asia). A. smithii could be confused with Acropyga stenotes because they both are small species that have distinctly longer than broad heads, but A. stenotes has 11-segmented antennae.

A. smithii is the only member of the decedens species-group known to possess broadly rounded paramere apices in the male. It shares several characteristics with Acropyga fuhrmanni such as elongated penis valves, antennal segment counts in the worker not greater than 8 segments and similarly shaped mandibles.

Key to New World Acropyga Workers / Queens / Males

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Brazil, Colombia, Costa Rica, Guatemala, Honduras, Lesser Antilles, Mexico, Panama, Peru, Saint Vincent and the Grenadines, Trinidad and Tobago, Venezuela.

From LaPolla (2004): The species has a large range from Central America (to Belize) southward, probably throughout tropical South America. It has also been found in the Lesser Antilles.

Biology
Lapolla (2004) - A. smithii is known to inhabit rainforests and cacao plantations. It occurs in the soil and litter; Weber (1944) reported nests from red clay soils down to a depth of 7.5 cm. Queens have been recorded from under the bark of a rotten log. Weber (1944) reported that at least two queens were found in one nest, indicating that this species may be polygynous. Winged reproductives have been collected from January-May. Two mealybug species have been recorded with this species, Neochavesia eversi, and Geococcus coffeae.

Nomenclature

 *  smithii. Acropyga (Rhizomyrma) smithii Forel, 1893g: 349 (q.) ANTILLES IS. Senior synonym of kathrynae, urichi: LaPolla, 2004a: 43.
 * kathrynae. Acropyga (Rhizomyrma) kathrynae Weber, 1944: 114, fig. 12 (w.) TRINIDAD. Junior synonym of smithii: LaPolla, 2004a: 43.
 * urichi. Acropyga (Rhizomyrma) urichi Weber, 1944: 115, figs. 2,3 (w.q.m.) TRINIDAD. Junior synonym of smithii: LaPolla, 2004a: 43.

Worker
From LaPolla (2004) - Head: yellow; covered in a layer of thick layer of appressed hairs; head distinctly longer than broad; posterior margin entire; 7-8 segmented, distinctly incrassate antennae; scape fails to reach posterior margin by about the length of the first two funicular segments; clypeus with abundant erect to suberect hairs; mandibles narrow with 4 distinct teeth; gap exists between inner mandibular margin and anterior clypeal margin. Mesosoma: pronotum rises gently from margin toward mesonotum; mesosomal dorsum flat; mesonotum and propodeum at about the same level; abundant suberect to erect hairs on mesonotum; metanotal area distinct; propodeum distinct; declivity steep. Gaster: petiole thick and erect, well below level of propodeum; gaster yellow; covered in a thick layer of appressed hairs, with scattered erect hairs throughout.

Measurements (n=13): TL: 1.23-1.62; HW: 0.316-0.364; HL: 0.36-0.408; SL: 0.192-0.251; ML: 0.354-0.449; GL: 0.492-0.764; CI: 81.86-97.2; SI: 58.02-69.76.

Queen
From LaPolla (2004) - As in worker with modifications expected for caste.

Measurements (n=2): TL: 2.07-2.24; HW: 0.395-0.408; HL: 0.427-0.449; SL: 0.256-0.281; ML: 0.627-0.634; GL: 1.02-1.16; CI: 90.87-92.51; SI: 64.81-68.87.

Male
From LaPolla (2004) - Head: brownish-yellow, darker around 3 prominent ocelli; head longer than broad; covered in layer of short appressed hairs with scattered, longer hairs, especially along sides: 9 segmented, slightly incrassate antennae, with apical segment about as long as three preceding segments; scape fails posterior margin by about length of pedicel; posterior margin entire; clypeus medially convex with many long erect hairs on surface; mandible narrow with 2 teeth, a small tooth at basal angle and a long apical tooth; apical tooth separated from basal tooth by a wide, smooth diastema; a slight gap exists between inner mandibular margin and outer clypeal margin. Mesosoma: light yellow; pronotum narrow and collar-like with only a few erect; pronotum overarched by mesonotum; mesonotum rounded anteriorly and covered in a layer of appressed hairs, occasionally with a few erect hairs; propodeum rounded; declivity steep. Gaster: petiole thick and erect; gaster yellow; covered in a layer of appressed hairs with scattered erect hairs throughout. Genitalia: in lateral view, parameres taper to rounded apices; posterior portion of parameres with many long erect hairs; cuspi short, round and each tapering to an apical point; digiti flat and anvil-shaped apically; cuspi meet digiti dorsally.

(n=2): TL: 1.5; HW: 0.275-0.287; HL: 0.313-0.324; SL: 0.208-0.21; ML: 0.474-0.51; GL: 0.65; CI: 87.86-88.58; SI: 73.17-75.64

Type Material
Acropyga (Rhizomyrma) smithii Forel, 1893: 349 (q.). Holotype queen, ST. VINCENT AND THE GRENADINES: St. Vincent, elev. 457.2 m, (H.H. Smith) (BMNH) [examined]. The holotype queen is labeled JSL TYPE #101.

Acropyga (Rhizomyrma) kathrynae Weber, 1944: 114 (w.). 4 syntype workers, TRINIDAD: Maracas Valley. B.W.I. (N.A. Weber) (MCZC) [examined]. NEW SYNONYM.

Acropyga (Rhizomyrma) urichi Weber, 1944: 115 (w.q.m.). 2 syntype workers, 1 syntype queen, 1 syntype male, TRINIDAD: Maracas Valley. B.W.I. (N.A. Weber) (MCZC) [examined]. NEW SYNONYM.