Syscia sabahna Yamane et Mizuno, 2024

Yamane, Seiki & Mizuno, Riou, 2024, Three new species of the ant genera Ooceraea and Syscia (Hymenoptera: Formicidae: Dorylinae) from Sabah, Borneo, Asian Myrmecology (e 017004) 17, pp. 1-14 : 5-10

Syscia sabahna Yamane et Mizuno , sp. nov.

http://zoobank.org/ C5D128A4-5A0D-4634-9D59- BFF88E1AAE4D

Fig. 2A–D , Fig. 3A–C

Type material. Holotype: worker, Malaysia, Borneo, Sabah, Crocker Range, Inobong , 23.ii.2006, Sk. Yamane leg., SB06-SKY-06 (24SKYRM-03; ITBC) . Paratypes: 5 workers & 1 dealate queen, same data as above (24SKYRM-04–09; ITBC, SKYC) .

Nontype material examined. 3 workers, Sabah, Kinabalu Park, Poring , 600–700 m alt., 8.i.1998, Sk. Yamane leg. ( ITBC, SKYC) ; 5 workers, Sabah, Kinabalu Park, Tambuyukon , 29.iii.2013, Sk. Yamane, SB 13-SKY-14 ( ITBC, SKYC) ; 1 worker, Sabah, Tawau Hills National Park , 8.vii.1996, Sk. Yamane leg. ( SKYC) .

Worker description. Diagnosis. Body reddish brown with yellowish apical flagellomere of antenna and legs, extensively punctate/punctoreticulate. Antenna with 9 flagellomeres (11 antennomeres). Head in profile view with posterior portion of its ventral margin provided with lamellate flange. Propodeal declivity superficially sculptured and rather shiny, with transverse dorsal carina more or less complete. Petiole slightly longer than broad, postpetiole as broad as long.

Measurements (n=5). TL 2.3–2.5, HW 0.47–0.49, HL 0.61–0.63, SL 0.30–0.33, PrW 0.35–0.37, PtW 0.24–0.26, PtL 0.26–0.28, PtH 0.25–0.29, PptW 0.32–0.34, PptL 0.33, PptH 0.34–0.36, G1 W 0.52 – 0.53, 0.58–0.61. CI 75.8–80.3, SI 62.5–68.1, G1I 86.7–89.8.

Full description. Head in full-face view distinctly longer than broad, narrowed anteriad, with weakly convex lateral margin, very shallowly concave posterior margin and rounded posterolateral corner ( Fig. 2C ). Frontal carinae raised high, posteriorly very close to each other, slightly diverging anteriad; parafrontal ridge moderately developed, without anterior prominence. Clypeus lamellate, very short, with anterior and posterior margins convex ( Fig. 2C , arrow). Mandible subtriangular, in profile view down-curved; masticatory margin minutely serrate; basal margin entire. Antenna with 9 flagellomeres (11 antennomeres); scape when laid back slightly broadened apicad, weakly outwardly curved; pedicel small, broader than long; flagellomeres I–IV ring-like, each shorter than pedicel; club composed of 4- or 5 flagellomeres but poorly differentiated from preceding ones; apical flagellomere thick and long, much longer than four preceding flagellomeres combined, as long as scape. With head in profile view, posterolateral corner round; lamellate flange present along posteroventral margin of temple/ gena. Mesosoma in dorsal view ( Fig. 2A ) with straight anterior margin, parallel lateral margins and concave posterior margin that is carinate, completely lacking pro-mesonotal suture and metanotal groove. With mesosoma in profile view ( Fig. 2B ), dorsal outline shallowly convex, highest at mid-length; pronotum with anteroventral corner bluntly angled; its ventral margin with lamellate flange; pronoto-mesopleural suture deep; mesopleuron, metapleuron and lateral face of propodeum completely fused; metapleural gland orifice with elongate opening, partly masked with dorsal and ventral flaps, dorsally with several peripheral hairs; propodeum with posterior margin steep, without posterodorsal spine; propodeal lobe roundly produced backward. Propodeum in posterior view with declivity margined with continuous carina dorsally and laterally. Foretrochanter much larger than mid- and hindtrochanters, which are basally petiolate. With waist in dorsal view, petiole only slightly longer than broad, with straight lateral margin, slightly diverging posteriad; postpetiole broader than petiole, almost as long as broad, broadened posteriad. Petiole in profile view nearly as long as high, with node clearly separated from sternite; dorsal outline shallowly convex; subpetiolar process with beak-like anterior prominence that is downwardly directed, but shape of the process highly variable; postpetiole as long as high with convex dorsal and ventral margins; its anteroventral margin rather sharply carinate ( Fig. 2D ). Gastral tergite I much broader than postpetiole, longer than broad (G1I 86.7–89.7), longer than other tergites combined, broader posteriorly than anteriorly; cinctus well differentiated and cross-ribbed on tergite but obsolete on sternite ( Fig. 2D , cinc); presclerite transversely striate, slightly ‘narrowed’ around border of tergite and sternite ( Fig. 2D ); last sternite laterally margined with carinae.

Body almost entirely covered with dense punctation or puncto-reticulation. Clypeus finely sculptured and weakly shiny; area mesad to parafrontal ridge smooth and shiny. Mandible with punctures but rather shiny. Antennal scape with dense medium-sized punctures. Entire apical flagellomere and basal portions of flagellomeres VII–IX punctate and matte. Posterior face of propodeal declivity superficially sculptured and shiny. All coxae minutely punctate; all tarsi microsculptured and matte; forefemur and foretibia superficially punctate and shiny, other femora and tibiae more coarsely punctate and matte.

Dorsum of body almost entirely covered with erect/suberect/decumbent short hairs, mixed with sparser long hairs; venter of postpetiole and gaster with similar pilosity; venter of petiole with a few erect hairs anteriorly.Antennae covered with dense short erect/suberect hairs mixed with sparser, slightly longer erect hairs; apical flagellomere almost without long hairs. Legs with dense, short decumbent hairs; longer erect/suberect hairs much sparser. Body entirely yellowish to reddish brown; mandible, apical flagellomere and legs much paler.

Queen description. Measurements (n=1): TL 3.0 mm, HW 0.51, HL 0.61, SL0.34, EW 0.09, EL 0.10, PrW 0.49, PtW 0.29, PtL 0.28, PtH 0.41, PptW 0.37, PptL 0.35, PptH,0.27, G1 W 0.62; G1L 0.94; CI 85.0, SI 66.7, G1I 66.0.

Description. Very similar to worker in size, structure, sculpture, pilosity and coloration except for caste-specific characters mainly seen in head and mesosoma ( Fig. 3 ). Body size almost same as that of worker (but see measurements). Parafrontal ridge with incision at mid-length (throughout entire in worker). Eye hemispherical, located on lateral face of head at midlength of cranium, with ca. 15 ommatidia along longest axis and a few suberect hairs; with head in full-face view outer margin of eye distinctly projecting from lateral margin of head. Complete set of ocelli present that are arranged in flat triangle; all ocelli with same size. With mesosoma in dorsal view, mesoscutum longer than pronotum, anteriorly strongly narrowed, with round apex; scutoscutellar suture straight; main disc of mesoscutellum much shorter than mesoscutum, broader than long, distinctly narrowed posteriad; metanotum very short (‘narrow’), sharply defined anteriorly and posteriorly by microgrooves; propodeum slightly narrower than mesonotum, as long as mesoscutellum, posteriorly margined with carina ( Fig. 3A , arrow). With mesosoma in profile view, dorsal outline shallowly convex; pronotum with steep anterior margin and short dorsal margin; pronoto-mesopleural sulcus complete; mesopleuron not divided into upper and lower sections; separation of mesopleuron from metapleuron clear only in upper one-third ( Fig. 3B , arrow); metapleuron and lateral face of propodeum completely fused.

Remarks. This species is differentiated from related Asian species with 11 antennomeres by the following combination of character conditions: 1) posterolateral lamellate zone (flange) of head rather developed, 2) anterior clypeal margin distinctly convex, 3) posterodorsal carina on propodeal declivity complete or only partly interrupted medially, 4) cinctus of gastral segment I clearly defined, cross ribbed, 5) punctation on head dorsum, gastral tergites III and IV very coarse (with ca. 20 large punctures on a line across head dorsum in full-face view) 6) in profile view dorsa of petiole, postpetiole and gastral tergite I roundly convex, 7) subpetiolar process ill-developed, not distinctly produced ventrad.

This species inhabits good forests. The colony SB06-SKY-06 (type series) was collected from rotting wood, and SB13-SKY-14 from leaf litter. Syscia sp. 9 of SKY collected from Lambir National Park , Sarawak, Borneo ( Yamane et al 2021) well agrees with the present new species .

Etymology. The specific epithet derives from the type locality (Sabah).

Figures

Fig. 2. Syscia sabahna sp. nov., paratype worker:A) habitus in dorsal view B) habitus in profile view C) head infullface view (arrow: anterior margin of clypeus) D) cinctus and presclerites of gastral segment I (abdominal segment IV) (arrow: narrowed part of presclerite ring). cinc, cinctus; gt1, gastral tergite I (posttergite); ppt, postpetiole; prs, presternite; prt, pretergite; pt, petiole.

Fig. 3. Syscia sabahna sp. nov., paratype dealate queen:A) habitus in dorsal view (arrow: metanotum) B) habitus in profile view (arrow: groove separating mesopleuron and metapleuron) C) head in full-face view.