Myopias etsukoae, 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 : 609-611

Myopias etsukoae , new species

( Fig. 1 )

Types. Holotype: worker (BOR-JWY-01, UMS), East Malaysia, Borneo, Sabah, Danum Valley , 30 April 2000, coll. C. Brühl. Paratypes: nine workers (BOR-JWY-02 to

BOR-JWY-10, SKYC), and two workers (BOR-JWY-11 and BOR-JWY-12, THNHM), same locality as holotype .

Worker description ( Fig. 1 )

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. Paratypes (n = 4): TL 4.85–4.92, HL 0.96–0.99, HW 0.83–0.86, SL 0.66–0.69, ED 0.17–0.20, ML 0.66–0.69, PW 0.66, MSL 1.39–1.42, PL 0.43–0.46, PH 0.50–0.56, DPW 0.40–0.43; CI 86–87, SI 77–84, OI 19–24, MI 69–70, LPI 115–123, DPI 92–100.

Head. In full-face view, head longer than broad (CI 86–87) (almost as long as broad when excluding median clypeal lobe), broader posteriorly, with sides convex and posterior margin almost straight; posterolateral corner of head roundly convex. Frontal lobe long, much longer than median clypeal lobe, slightly translucent. Median longitudinal frontal sulcus deep, extending near mid-length of head. Median clypeal lobe rectangular or weakly widened anteriad, slightly broader than long, with a pair of diverging long lateral spines; its anterior margin shallowly convex, bearing minute median denticle. Mandible robustly linear and subfalcate, relatively short, and in profile down-curved; masticatory margin with four teeth, i.e., large basal tooth, large prebasal tooth, minute preapical tooth (denticle), and medium-sized apical tooth — the first three teeth are widely spaced, but preapical denticle is almost attached to the base of apical tooth; basal margin with well-defined protuberance. Eye relatively large, with ca. 20 ommatidia, 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 enlarged toward apex to approximate width of frontal lobe, reaching posterior margin of head; antennal segment II longer than broad and longer than each of segments III– VII; segments III–VII each broader than long; four apical segments forming a club.

Mesosoma. Stout, in profile with dorsal outline of promesonotum convex, sloping gradually to metanotal groove; promesonotal suture and metanotal groove distinct; mesopleuron clearly demarcated from metapleuron and mesonotum by shallow grooves composed of row of punctures, and divided into upper and lower portions by similar groove; metapleuron not demarcated from lateral face of propodeum; pronotum broader than mesonotum and propodeum in dorsal view. In profile view, propodeum relatively long and convex dorsal outline; junction roundly convex; declivity more or less flat.

Metasoma. Petiole in profile view subrectangular and sessile, higher than long, its anterior and posterior faces vertical, dorsal face weakly convex; in dorsal view petiolar node subrectangular, clearly broader than long (DPI 92–100), broader posteriorly; subpetiolar process well developed, subtriangular, with apex truncate and directed downward; anterior margin of subpetiolar process convex, while posterior margin almost straight and distinctively longer than the former. Gaster (abdominal segments III–VII) elongate, in dorsal view, gastral segment I slightly narrower than II. Sting long, sharp and upcurved.

Dorsum of head punctate but interspaces smooth and shiny; lateral and ventral faces of head smooth and shiny. Pronotum and mesonotum smooth and shiny; mesopleuron largely smooth and shiny with sparse punctures in upper portion; metapleuron with smooth and shiny upper portion and irregularly striate lower portion; propodeum with shiny dorsum and irregularly striate lateral face. Lateral face of petiole irregularly striate, while dorsal face smooth and shiny. Gaster smooth and shiny. Legs 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 long erect hairs and dense appressed hairs. Body extensively reddish brown; head and pronotum paler than propodeum, petiole, and gastral segments I–II; mandible, antenna, and tip of gaster yellowish brown.

Etymology. The specific name is dedicated to Ms. Etsuko Yamane, who has supported our activity for a long period.

Habitat. Primary rainforest.

Distribution. Borneo (Sabah).

Remarks. Myopias etsukoae , new species, is most similar to Myopias castaneicola ( Donisthorpe, 1938) from New Guinea in having a reddish brown body and deep metanotal groove. However, it can be separated from M. castaneicola by the following characteristics: 1) anterior margin of median clypeal lobe concave, its median portion with minute denticle (concave without minute tooth at median portion in M. castaneicola ); 2) posterior margin of head almost straight (weakly concave in M. castaneicola ); 3) lateral faces of proprodeum and petiole strongly sculptured (smooth and shiny in M. castaneicola ); 4) dorsal outline of propodeum weakly convex (almost straight in M. castaneicola ).

Figures

Fig. 1. Myopias etsukoae, new species, worker (holotype, BOR-JWY-01, UMS). A, body in profile view; B, head in full-face view; C, body in dorsal view.