Syscia guizhouensis ( Zhou, 2006 ) Du & Xu & Chen, 2024

Du, Congcong, Xu, Zhenghui & Chen, Zhilin, 2024, Taxonomic account of the ant genus Syscia Roger, 1816 (Hymenoptera, Formicidae) from Asia, with descriptions of two new species from China, European Journal of Taxonomy 930, pp. 157-181 : 168-173

Syscia guizhouensis ( Zhou, 2006) comb. nov.

Figs 6–7 , Table 1

Cerapachys guizhouensis Zhou, 2006: 581 , figs 1–2 (w.). China.

Ooceraea guizhouensis – Bharti et al. 2021: 181.

Diagnosis

Workers have 11-segmented antennae, body color brown with antennae and legs yellowish brown. Head in full-face view subrectangular, distinctly longer than broad. Mesosoma in dorsal view subrectangular with almost parallel lateral sides; in lateral view, dorsal outline slightly convex. Petiole in dorsal view elliptical, longer than broad, with lateral margins convex; in lateral view, petiolar node (excluding sternite) subtrapezoid with slightly convex dorsal outline, bilateral edge slop, and slightly concave; subpetiolar process in lateral view subtrapezoid, with posterior outline strongly concave, and ventral margin very short and almost straight. Postpetiole in lateral view slightly higher than long, sternite anteroventrally produced as nearly orthogonal directed downward and forward.

Type material

Holotype (worker) CHINA • Guizhou, Tongren City, in the Fanjingshan National Nature Reserve ; 27.911945° N, 108.696634° E; 2195.00 m a.s.l.; 3 Jun. 2002; Shanyi Zhou leg; No. GXNU 060127; GXNU: GXNU060127 .

Paratypes (workers) CHINA • 1 worker; same collection data as for holotype; GXNU: SWFU 060127-1 • 1 worker; same collection data as for holotype; SWFU: GXNU 060127-2 • 1 worker; same collection data as for holotype; IZCAS: GXNU 060127-3 .

Other material examined

CHINA • 1 spec; Xizang, Linzhi City, Motuo Town, Motuo Village ; 29.32° N, 95.34° E; 1230 m a.s.l.; 27 Aug. 2016; Zhilin Chen leg.; No. G160363; GXNU: G160363 .

Redescription

MEASUREMENTS AND INDICES. Holotype worker: BL 3.20, HL 0.60, HW 0.45, CI 75, SL 0.31, SI 69, MW 0.33, ML 0.85, PL 0.35, PH 0.32, PW 0.27, PI1 107, PI2 77, PPL 0.41, PPH 0.45, PPW 0.42, PPI1 91, PPI2 102, WI 156. Paratype worker: BL 3.10–3.25, HL 0.60–0.63, HW 0.43–0.45, CI 71–72.00, SL 0.30–0.33, SI 69–75, MW 0.33–0.35, ML 0.81–0.84, PL 0.33–0.34, PH 0.32–0.33, PW 0.26–0.28, PI1 102–105, PI2 75–85, PPL 0.40–0.43, PPH 0.42–0.43, PPW 0.40–0.43, PPI1 95–99, PPI2 100–102, WI 154–169 (n = 3) (individual measurements see Table 1 ).

Worker

HEAD. Antennae with 11 segments; apical antennal segment (XI) conspicuously enlarged, much broader than and longer than two preceding segments (IX–X) combined. In full-face view, head subrectangular, distinctly longer than broad, lateral margins slightly convex and convergent from middle to posterior, and posterior margin slightly concave, with posterolateral corner acute ( Fig. 6A ). Frontal carinae short and narrow, not reaching to middle of head, with anterior half sharply elevated and posterior half low and vestigial in profile. Clypeus short, anterior margin almost straight. Eyes and ocelli completely absent ( Fig. 6A ). Mandibles triangular; masticatory margin serrated, without distinct teeth ( Fig. 6A ).

MESOSOMA. In dorsal view, robust and subrectangular, with almost parallel lateral sides, anterior margin slightly convex, and posterior margin slightly concave ( Fig. 6B ); in lateral view, dorsal outline slightly convex; promesonotal suture and metanotal groove absent; mesopleuron demarcated from pronotum by distinct suture, but not demarcated from mesonotum and metapleuron; mesopleuron also not differentiated from metapleuron ( Fig. 6C ). Propodeal declivity straight, encircled with distinct thin rim ( Fig. 6C ).

METASOMA. In dorsal view, petiole elliptical, longer than broad ( Fig. 6B ); in lateral view, petiolar node (excluding sternite) subtrapezoid with slightly convex dorsal outline, anterior edge slightly concave and poster edge sloped ( Fig. 6C ). Subpetiolar process in lateral view subtrapezoid, with posterior outline strongly concave, and ventral margin very short and almost straight ( Fig. 6C ). Postpetiole in dorsal view clearly larger than petiole, subtrapezoid, anterior margin slightly concave and shorter than posterior margin, lateral margins slightly convex ( Fig. 6B ); in lateral view, postpetiole higher than long; dorsal outline obviously convex; postpetiolar sternite in lateral view really low, with ventral margin convex, anteroventrally produced as nearly orthogonal directed downward and forward ( Fig. 6C ). Abdominal tergite IV (second gastral tergite) in dorsal view elongate, subrectangular with lateral margins slightly convex, anterior margin strongly concave, and lateral margins slightly convex ( Fig. 6B ).

SCULPTURE. Entire body with numerous, relatively small, closely-spaced foveolae ( Fig. 6 ). Antennal scape, outer surface of mandible, and legs with fine dense micropunctures ( Fig. 6 ).

PILOSITY. Body entirely covered with densely long and short decumbent, sub-erect and erect hairs.

COLORATION. Body brown. Antennae and legs yellowish brown ( Fig. 6 ).

Distribution

China (Guizhou, Xizang).

Habitat

The nest of Syscia guizhouensis was found in the Fanjingshan National Nature Reserve, Guizhou, China. The sampled site is located in an evergreen broad-leaf forest, on the soil surface under the falling leaves.

Recognition

Syscia guizhouensis is similar to S. humicola , but can be distinguished from S. humicola by the following characteristics: 1) subpetiolar process in lateral view subrectangular in S. guizhouensis (subpetiolar process in lateral view subtriangular in S. humicola ); 2) in full-face view posterior half of the head trapezoidal, narrower posteriorly in S. guizhouensi (in full-face view posterior half of the head rectangular in S. humicola ); 3) in lateral view anterior margin of petiole concave in S. guizhouensis (in lateral view anterior margin of petiole sloped and slightly convex in S. humicola ).

Syscia guizhouensis is also similar to a species from Thailand, S. chaladthanyakiji , in the general appearance of workers with 11-segmented antennae. However, S. guizhouensis can be distinguished from S. chaladthanyakiji by the following characteristics: 1) dorsal outline of mesosoma in lateral view slightly convex in S. guizhouensis (nearly straight in dorsal view in S. chaladthanyakiji ); 2) petiole in dorsal view obviously elliptical, longer than broad; in lateral view trapezoidal with slightly convex dorsal outline, bilateral edge slop and anterior edge slightly concave in S. guizhouensi (obviously rectangular in dorsal view, broader than long; in lateral view rectangular with convex dorsal outline, bilateral edge vertical in S. chaladthanyakiji ); 3) subpetiolar process in lateral view subtrapezoid, with posterior outline strongly concave, and ventral margin very short and almost straight in S. guizhouensis (subrectangular with ventral outline concave in S. chaladthanyakiji ); 4) postpetiolar sternite in lateral view anteroventrally produced as nearly orthogonal directed downward and forward in S. guizhouensi . (reduced into blunt angle directed downward and forward in S. chaladthanyakiji ); 5) body color darker, reddish brown in S. guizhouensis (brown in S. chaladthanyakiji ).

Figures

Fig. 6. Syscia guizhouensis (Zhou, 2006) comb. nov., holotype, worker (No. G160363). A. Head in fullface view. B. Body in dorsal view. C. Body in lateral view (imaged by Zhilin Chen).

Fig. 7. Syscia guizhouensis (Zhou, 2006) comb. nov., worker (No. G160363). A. Head in full-face view. B. Petiole and postpetiole in dorsal view. C. Body in dorsal view. D. Body in lateral view (imaged by Zhilin Chen).