Sphinctomyrmex furcatus (Emery, 1893)

W. Jaitrong, D. Wiwatwitaya & W. Sakchoowong, 2016, Review of the Thai Species of the Genus Sphinctomyrmex Mayr, 1866 (Hymenoptera: Formicidae, Dorylinae), with Description of a New Species, Far Eastern Entomologist 305, pp. 1-9 : 4-5

Sphinctomyrmex furcatus (Emery, 1893)

Figs 1– 4

Eusphinctus furcatus Emery, 1893: 275 ( syntypes – workers from Myanmar, Palon, Pegu , VIII. IX 1887, L. Fea leg.) .

Sphinctomyrmex furcatus: Emery, 1895: 457 ; Bingham, 1903: 25; Brown, 1975: 75; Bolton, 1995: 392.

MATERIAL. Thailand: Trang Province, Nayong District, evergreen forest, 16.IV 2000, colony no. WJT 160400 -1, 5 workers ( THNHM-I-00001 to THNHM-I- 00005 ), W. Jaitrong leg .; Saraburi Province, Ched Kod , dry evergreen forest, 4.VII 2003, 1 worker ( THNHM-I-00006 ), S. Hasin leg .

REDESCRIPTION. 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.

MEASUREMENTS. 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.

DISTRIBUTION. India, Myanmar (type locality) and Thailand (Saraburi and Trang Provinces, new record).

REMARKS. Sphinctomyrmex furcatus is similar to S. taylori Forel, 1900 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, S. furcatus is easily separated from S. taylori by the following conditions: body larger ( WL 1.68-1.78 mm in S. furcatus while WL 1.27 mm in S. talori ); petiole longer than broad (broader than long in S. taylori ); body color darker (deep reddish brown in S. furcatus while light reddish brown in S. taylori ).