Eusphinctus furcatus

In Thailand this species has been collected in evergreen forests (Jaitrong et al., 2016).

Identification
Jaitrong et al. (2016) - Eusphinctus furcatus is similar to Eusphinctus taylori in general appearance as they share the pygidial apex deeply notched (as seen from above), 11-segmented antenna, reddish brown body and swollen mesosoma. However, E. furcatus is easily separated from E. taylori by the following conditions: body larger (WL 1.68-1.78 mm in E. furcatus while WL 1.27 mm in E. taylori); petiole longer than broad (broader than long in E. taylori); body color darker (deep reddish brown in E. furcatus while light reddish brown in E. taylori).


 * Larger species (WL 1.68-1.78 mm); body deep reddish brown; petiolar node longer than broad (India, Myanmar, and Thailand) . . . . . Eusphinctus furcatus


 * Smaller species (WL 1.27 mm); body light reddish brown; petiolar node broader than long (India) . . . . . Eusphinctus taylori

Distribution based on Regional Taxon Lists
Oriental Region: India, Myanmar, Thailand.

Biology
A. B. Soans and W. L. Brown collected two colonies of E. furcatus in Kottiyoor, Kerala, India. One was located in leaf litter near a rotting log and the other one was found under a stone in a shaded creek bottom. There were about 50 workers in each of the observed nests, and one colony contained two ergatoid gynes (Brown 1975).

Nomenclature

 *  furcatus. Eusphinctus furcatus Emery, 1893a: cclxxv (w.) MYANMAR.
 * [Also described as new by Emery, 1895k: 457.]
 * Combination in Sphinctomyrmex (Eusphinctus): Emery, 1895k: 457.
 * Combination in Eusphinctus: Borowiec, 2016: 144.
 * See also: Bingham, 1903: 25; Brown, 1975: 75.

Worker
Jaitrong et al. (2016) - Non-type worker (n = 6): TL 6.85-6.90 mm, HL 1.12-1.16 mm, HW 1.02-1.09 mm, SL 0.61-0.63 mm, EL 0.03-0.05 mm, WL 1.68-1.78 mm, PL 0.61-0.63 mm, PW 0.58-0.63 mm, CI 91-94, SI 58-61, OI 3-5.

Head in full-face view almost as long as broad, subrectangular, slightly broader posteriorly with side convex and posterior margin feebly concave; posterior corners of head bluntly angular; occipital margin bearing a narrow collar. Eye present, located in a foveola at middle of lateral face of head. Antenna 11-segmented; antennal scape relatively short, reaching midlength of head; II-VI each shorter than broad; XI slightly longer than VII+VIII+IX+X. Frontal carina short, extending 1/3 of head length, fused at posteriormost portion to form a single carina; parafrontal ridge extending posteriorly less than 1/3 of head length. Clypeus narrowly inserted between frontal carinae; median portion of clypeus with a distinct tubercle, anterior clypeal margin strongly concave. Mandible subtriangular, with basal margin rounding into masticatory margin; the latter apparently edentate.

Mesosoma stout and swollen, in profile with almost flat dorsal outline; promesonotal suture and metanotal groove obliterated; mesopleuron clearly demarcated from promesonotum by a deep groove and from metapleuron and lateral face of propodeum by a carina; propodeal junction obtusely angulated; declivity of propodeum shallowly concave, and encircled with a distinct rim.

Petiole in profile rectangular and sessile, clearly longer than broad, its dorsal outline straight, anterior and posterior faces vertical; subpetiolar process well developed, subtriangular, its apex truncate and directed downward, anterior margin convex, while posterior margin concave.

Gaster elongate, gastral segments I and II clearly separated by distinct constrictions, segments III, IV, and V separated from each other by deeply impressed, short constrictions; in dorsal view, gastral segment I (abdominal segment III) slightly narrower than gastral segment II, as broad as segment III, and broader than segment IV; segment III larger than IV in width and length; dorsum of pygidium shallowly concave with a row of spines laterally, pygidial apex deeply notched as seen from above.

Head with dense foveolae, foveolar intervals broad, smooth and shiny; antennal scrobe finely superficially reticulate but shiny; dorsum of mesosoma largely smooth and shiny with sparse, very shallow foveolae; lateral faces of pronotum, mesopleuron, metapleuron and propodeum with dense foveolae, foveolar intervals superficially shagreened but shiny; lateral face of petiole reticulate; each gastral segment with generally smooth and shiny.

Pilosity comparatively sparse; dorsum and lateral face of head with sparse standing hairs mixed with sparse short decumbent hairs; dorsa of mesosoma, petiole, gaster with sparse standing hairs; pygidium and hypopygium with dense longer hairs.

Body entirely deep reddish brown.

Type Material
Jaitrong et al. (2016) – syntypes, workers from Myanmar, Palon, Pegu, VIII.IX 1887, L. Fea leg.