Acanthognathus stipulosus

The worker holotype was taken from a leaf litter berlesate sample from rainforest. This is the first record of the genus from the middle Amazonian region. It must be uncommon, for it was taken only once out of many Berlese funnel extractions from the Manaus area.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 * . Acanthognathus stipulosus Brown & Kempf, 1969: 104, fig. 3 (w.) BRAZIL (Amazonas).
 * Type-material: holotype worker.
 * Type-locality: Brazil: Amazonas, NE of Manaus, branch of Rio Taruma, high falls (Cachoeira Alta), 28.viii.1962 (W.L. Brown).
 * Type-depository: MCZC.
 * Status as species: Kempf, 1972a: 9; Bolton, 1995b: 53; Bolton, 2000: 17; Galvis & Fernández, 2009: 248 (in key).
 * Distribution: Guyana, Brazil.

Worker
Holotype. Measurements and indices given in Table. A small-sized, slender species resembling Acanthognathus ocellatus and Acanthognathus brevicornis.

The character that immediately sets this species off from the rest is the shape of its petiole (Fig. 3). Set on a long, gently curved peduncle, the node is compressed anteroventrally, and is sharply rounded above in side-view profile. Seen from above, the anterior peduncle is about 3x times as long as the node, and the posterior peduncle about half as long ; the node itself is about o.IO mm long and 0.18 mm wide, with a convex anterior face and a flat, sloping posterior face; the anterior peduncle widens gradually behind the spiracles to receive the node. Seen from behind, the node is some­what like a Formica petiole in outline, with broadly rounded crest, bulging sides and narrower ventral portion. Postpetiole about 0.16 mm long, 0.17 mm wide, subcircular as seen from above, with straight anterior margin.

Also the following characters:(1) Mandibles relatively shorter than in ocellatus, their preapical borders unarmed except for an almost imperceptible "submedian welt." (2) Humeral teeth triangular, strongly projecting, rendering the promesonotum very  slightly broader than long (cervix excluded). Sculpture of promesonotum consisting of about 8 slightly wavy costulae running anteriad from the metanotal groove and fanning out to meet 2-3 short transverse costulae on the anterior pronotum ; costulae and interspaces shining; cervix smooth and shining. (3) Propodeal dorsum gently convex, smooth and shining discad; spines long and nearly straight as seen from side, but slightly di­vergent with apices incurved as seen from above; moderately elevated. (4) Head smooth and shining, with spaced but large and distinct round fossae over the dorsum, each centrally tuberculate and bearing an inclined, short, white clavate hair. Sides of alitrunk loosely rugose, shining; rest of body and most parts of appendages smooth and shining. (5) Color reddish ferruginous, gaster darker, reddish-brown ; legs, mandibles and antennae pale straw yellow, middle and posterior femora each with a broad subapical brownish band.

Type Material
Holotype. A unique taken in rain forest near the quarry at the high falls (Cachoeira Alta) of a branch of the Rio Tamma, northeast of Manaus, Amazonas,  Brasil; 28 August  1962, W. L. Brown, Jr., leg. The worker was taken from a leaf litter berlesate.

References based on Global Ant Biodiversity Informatics

 * Campos R. B. F., J. H. Schoereder, and C. F. Sperber. 2007. Small-scale patch dynamics after disturbance in litter ant communities. Basic and Applied Ecology 8: 3643.
 * Siqueira de Castro F., A. B. Gontijo, W. Duarte da Rocha, and S. Pontes Ribeiro. 2011. As comunidades de formigas de serapilheira nas florestas semidecíduas do Parque Estadual do Rio Doce, Minas Gerais. MG.BIOTA, Belo Horizonte 3(5): 5-24.