Myopias striaticeps, Jaitrong & Wiwatwitaya & Yamane, 2020

Jaitrong, Weeyawat, Wiwatwitaya, Decha & Yamane, Seiki, 2020, Three new species of the ant genus Myopias Roger, 1861 (Hymenoptera: Formicidae: Ponerinae) from Borneo, Raffles Bulletin of Zoology 68, pp. 608-618 : 611-612

Myopias striaticeps , new species

( Figs. 2 , 3 )

Types. Holotype: worker (BOR-JWY-13, UMS), Borneo, East Malaysia, Sabah, Crocker Range N.P., Mahua Waterfall area , 4–5 November 2000, coll. Sk. Yamane. Paratypes: one gyne with same data as holotype (BOR-JWY-14, THNMH); one worker , Borneo, Kinabalu Park, Sayap Kinabalu (ca. 1,000 m alt.), 16 July 1996, coll. Sk. Yamane (BOR-JWY-15, SKYC) .

Non-type material examined. One worker, Sabah, Kinabalu Park, Poring (550 m alt.), 17 March 1995, Sk. Yamane; one worker, same loc. (altitude unknown), 23 August 1997, Sk. Yamane; one worker, Sabah, Tawau Hills NP, 10 July 1996, Sk. Yamane ; one worker, Sarawak, Lambir Hills NP, Tourist area , 20 January 1993, Sk. Yamane .

Worker description ( Fig. 2 ) Measurements. Holotype: TL 4.92, HL 0.99, HW 0.86, SL 0.66, ED 0.20, ML 0.69, PW 0.69, MSL 1.45, PL 0.46, PH 0.56, DPW 0.43; CI 87, SI 77, OI 23, MI 70, LPI 121, DPI 93. Paratype: TL 4.1, HL 1.08, HW 0.87, SL 0.73, EL 0.17, ML 0.65, PW 0.70, MSL 1.55, PL 0.46, PH 0.60, DPW 0.46; CI 81, SI 84, OI 20, MI 60, LPI 130, DPI 100.

Head. In full-face view, head clearly longer than broad (CI 81–87), subrectangular with sides weakly convex and posterior margin weakly concave; posterolateral corner of head bluntly angulate (note that the head is almost as long as broad if the anterior median lobe of the clypeus is excluded). Frontal lobe low, passing over lateral portion of anterior clypeal margin; frontal lobe slightly longer than median clypeal lobe. Median longitudinal frontal sulcus deep, extending slightly beyond ⅓ of head length. Median lobe of clypeus subrectangular, slightly broader than long, its anterior margin distinctly concave to form roundly produced lateral corners. Mandible robustly linear and subfalcate, relatively long, down-curved in profile; masticatory margin with four teeth, i.e., large basal tooth, large prebasal tooth, minute preapical denticle, and sharp apical tooth (the first three are widely spaced, but preapical denticle is almost attached to the base of the apical tooth); basal margin with well-defined protuberance. Eye relatively large, composed of ca. 15 ommatidia along longest axis, located close to base of mandible; distance between mandibular base and anterior margin of eye almost as long as length of eye. Antennal scape robust and gradually widened to its midlength where its width approximates width of frontal lobe, not reaching posterior margin of head; antennal segment II longer than broad and longer than each of segments III–VIII; segments III–VIII each shorter than broad; four apical segments forming club.

Mesosoma. Stout, in profile with dorsal outline of promesonotum weakly convex, sloping gradually to metanotal groove; promesonotal suture and metanotal groove distinct; mesopleuron clearly demarcated from metapleuron by shallow grove composed of chain of punctures and from mesonotum by more vague furrow, not clearly divided into upper and lower portions; metapleuron not demarcated from lateral face of propodeum, pronotum broader than mesonotum and propodeum in dorsal view. Propodeum in profile, weakly convex dorsal outline; junction obtusely angulate; declivity more or less flat.

Metasoma. Petiole in profile subrectangular and sessile, slightly higher than long, its anterior face vertical, dorsal and posterior faces weakly convex; in dorsal view, petiolar node subrectangular, slightly longer than broad (DPI 93), broader posteriorly; subpetiolar process well developed, in profile view subtriangular, apically truncate and directed downward; its anterior margin convex, while posterior margin weakly concave and distinctively longer than anterior margin. Gaster elongate, in dorsal view, gastral segment I slightly narrower than II. Sting long, sharp and upcurved.

Entire dorsum of head with irregular longitudinal striae; lateral and ventral faces of head smooth and shiny. Mesosomal dorsum entirely with irregular longitudinal striae; mesopleuron, metapleuron, and lateral face of propodeum striate from front to rear; lateral face of pronotum smooth and shiny; propodeal dorsum with longitudinal striation, and declivity with fine transverse striation. Petiole largely smooth and shiny. Gaster smooth and shiny. Legs predominantly smooth and shiny. Dorsum of head with sparse long hairs mixed with dense shorter hairs; dorsa of mesosoma and metasoma with dense long hairs mixed with sparse short hairs; tip of metasoma with dense standing hairs; tibiae with sparse suberect long hairs and dense appressed hairs. Dorsum of head dark brown, while its ventral face reddish brown; mesosoma entirely dark brown; petiole and gastral segments I–II dark brown; remaining gastral segments yellowish brown; mandible, antenna, and legs reddish brown.

Dealate gyne description ( Fig. 3 )

Measurements. Paratype (n = 1). TL 5.64, HL 1.06, HW 0.92, SL 0.69, ED 0.26, ML 0.69, PW 0.73, MSL 1.62, PL 0.46, PH 0.59, DPW 0.46, CI 88, SI 75, OI 29, MI 66, LPI 129, DPI 100.

Similar to the worker in structure, sculpture, pilosity, and colouration, with the following conditions that should be noted: body slightly larger; head in full-face view rectangular, with almost parallel sides and straight posterior margin; eye large, located close to the base of mandible; distance between eye and mandibular base much shorter than eye length; median ocellus as large as lateral ocellus in dorsal view, mesoscutum trapezoidal with slightly protruding anterior border; with mesosoma in profile, mesoscutum slightly bulged anteriorly and flattened caudad; parapsidal lines indistinct; scutellum oblong, clearly broader than long; metanotum short; metanotopropodeal sulcus deeply impressed; propodeum in profile with almost straight dorsal outline; propodeal junction roundly convex; petiole clearly shorter than high; gaster larger than in the worker.

Etymology. The specific name refers to the fine striation on the dorsum of the head.

Habitat. The type series was collected from highland primary forests (ca. 1,000 m a.s.l.).

Distribution. Borneo (Sabah and Sarawak).

Remarks. Myopias striaticeps , new species, is most similar to M. philippinensis ( Menozzi, 1925) in having striae on the dorsa of the head and mesosoma. However, this species can be distinguished from the latter by the following characteristics in the worker caste: 1) propodeal junction obtusely angulate (roundly convex in M. philippinensis ); 2) with mesosoma in dorsal view, posterior margin of mesonotum strongly convex (almost straight in M. philippinensis ); 3) body entirely black to dark brown (reddish brown in M. philippinensis ); and 4) dorsum of head entirely strongly striate (anteriormost portion punctate with weak striation in M. philippinensis ). We examined four additional worker specimens that agree with the holotype in most characters. We omit these from the type series because they were collected from lowland forests, one in Lambir Hills National Park, Sarawak, and the other three from Poring, Sabah.

Figures

Fig. 2. Myopias striaticeps, new species, worker (holotype, BOR-JWY-13, UMS). A, body in profile view; B, head in full-face view; C, body in dorsal view.

Fig. 3. Myopias striaticeps, new species, dealate gyne (paratype, BOR-JWY-14, THNHM). A, body in profile view; B, head in full-face view; C, body in dorsal view.