Stictoponera bicolor

Gnamptogenys bicolor is abundant in some areas, as evidenced by its abundance in museum collections.

Identification
Lattke (2004) - Occipital lobes prominent, projecting posteroventrally in lateral view; eyes situated on posterior half of head, usually less than one eye diameter from vertex. Mesosomal dorsum densely foveolate to areolate, with median longitudinal strip of strigae-rugulae extending from posterior pronotum to mesonotum. Mesosomal dorsal margin with more than ten standing hairs in lateral view. Propodeal declivitous face medially with raised posteriorly diverging surface that usually ends before anterior margin in small oval depression. Metacoxal tooth slender and straight.

Distribution
Known from China, Malaysia, Myanmar, Thailand and Indonesia.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia, Malaysia. Oriental Region: India, Myanmar, Thailand, Vietnam. Palaearctic Region: China.

Biology
Lattke (2004) - In the closely related species Gnamptogenys menadensis, most reproduction is through gamergates (Gobin, Peeters, and Billen 1998a), so it seems reasonable to expect a similar situation for G. bicolor.

Most habitat labels indicate mesic, forested habitats, especially rotten wood, as the favorite haunt of this species.

Castes
Queens have not been collected for this species.

Nomenclature

 *  bicolor. Ectatomma (Stictoponera) bicolor Emery, 1889b: 493 (w.) MYANMAR. Lattke, 2004: 83 (m.). Combination in Stictoponera: Emery, 1911d: 48; in Gnamptogenys: Brown, 1958g: 227. Subspecies of coxalis: Emery, 1895k: 458; of menadensis: Emery, 1911d: 48; Wheeler, W.M. 1921c: 529. Status as species: Forel, 1900d: 316; Bingham, 1903: 83; Brown, 1950e: 245. Senior synonym of minor: Brown, 1950e: 245; of bannana: Lattke, 2004: 81. See also: Brown, 1954h: 4; Lattke, 2004: 80.
 * minor. Ectatomma (Stictoponera) bicolor var. minor Forel, 1900d: 317 (w.) MYANMAR. [Unresolved junior primary homonym of Ectatomma mucronatum var. minor Forel, 1899c: 9 (now in Acanthoponera).] Junior synonym of bicolor: Brown, 1950e: 245.
 * bannana. Gnamptogenys bannana Xu & Zhang, 1996: 55, figs. 1-7 (w.) CHINA. Junior synonym of bicolor: Lattke, 2004: 81.

Lattke (2004) - This species shares with Gnamptogenys menadensis the protuberant occipital lobes and posteriorly displaced eyes and other features; consequently the two species are easily confused. Brown (1950, 1954b) described the variability in color and other morphological aspects that have caused confusion separating these species, as well as the reasons for the synonymy of G. minor. Even though Brown (1954b) cited the smooth promesonotal area in G. menadensis versus the strigulose surface in G. bicolor as a fairly reliable distinction, he still expressed the possibility of their synonymy. Gnamptogenys menadensis can be distinguished from G. bicolor in having (1) the lateral margins of the frontal lobes tending to be straight and parallel to each other; (2) the promesonotum with a smooth longitudinal median area; (3) the propodeal declivity with a parallel-sided raised area; and (4) the metacoxal tooth usually bent close to its base. G. menadensis generally has fewer foveolae on the postpetiole, and they are shallower and smaller in diameter than in G. bicolor. The sides of the fourth abdominal tergite in G. menadensis tend to be smoother with less-developed punctae. The hairs on the mesosomal dorsum of G. menadensis are very short, rarely protruding above the foveolae from which they originate.

Xu and Zhang (1996) described Gnamptogenys bannana from a series of workers taken in southern China. They describe it as very close to G. bicolor but differing in the development of the occipital lobe, gauge of the foveolate sculpture, and coloration. The color scheme of G. bannana can be found in G. bicolor, and the development of the occipital lobe also fits G. bicolor. The metrics for their type series mostly overlap those of G. bicolor specimens found in southern China. The ants were examined in 1997 by the myrmecologist Zhou Shanyi, and he could not find any difference between G. bannana and G. bicolor. So although the types were not personally seen in the course of this revision, it seems relatively safe to recognize G. bannana as a junior synonym of G. bicolor.

Wu and Wang (1995:36) included G. bicolor in a key to the species of Gnamptogenys present in China. Comments under Gnamptogenys menadensis provide an additional discussion of differences between these two species.

Worker
Lattke (2004) - Metrics (n = 10): HL 1.03-1.46, HW 0.86-1.17, ML 0.53-0.69, SL 0.79-1.17, ED 0.21-0.28, WL 1.37-1.96 mm. CI 0.78-0.88, SI 0.92-1.03, MI 0.57-0.66, OI 0.22-0.27. Head with broadly convex lateral margins that converge anteriorly in frontal view, posterior margin relatively straight with lateral protruding occipital lobes, anterior margin of clypeal lamella forming blunt angle, sometimes projecting anterad as narrow lobe with straight to weakly sinuate sides; frons rugulose-foveolate with sharp, roughly longitudinal ridges, foveolae with smooth, convex bottoms; frontal triangle divided through middle by longitudinal ridge; frontal lobe with subparallel lateral margin; scape with variable degree of longitudinal strigulae, from very strigulose to mostly smooth; clypeus longitudinally strigose. Occipital lobe prominent, projecting posteroventrally in lateral view; occipital lamella convex, low, with extremities either angular or convex; eye situated on posterior half of head, usually less than one ocular diameter distant from vertex.

Pronotum with lamellate humeral angle, ventral pronotal margin relatively narrow, frequently with sharply angular anteroventral corner, densely foveolate with occasional fine strigulae posterad; promesonotal suture marked as series of transverse depressions; mesosomal dorsum densely foveolate to areolate with median longitudinal strip of strigae-rugulae extending from posterior pronotum to mesonotum; anepisterum narrow, rectangular to cuneiform, usually smooth with some foveolae; katepisternum foveolate, with or without strigulae; metapleuron posteroventrally strigose, anterodorsally with narrow strip of mostly smooth or undulate cuticle; propodeum foveolate, unarmed, declivitous face medially with raised surface that diverges posteriorly, elevated area usually ends in small oval depression before anterior propodeal margin, cuticle surrounding raised area usually smooth. Petiolar node dorsally foveolate, with subquadrate to lobe like ventral process in lateral view; postpetiolar dorsum foveolate, foveolae well impressed, denser anterad than posterad, tergite densely foveolate anterolaterally; postpetiolar sternum transversely strigulose, laterally punctate-foveolate; dorsum of abdominal segment 4 mostly smooth with scattered punctulae, laterally with scattered punctae. Fore coxa transversely strigulose in lateral view; fore tarsus opposite strigil with single prominent basal seta, occasionally followed apically by row of slender setae; metacoxal tooth straight and slender. Most of body with scattered suberect to subdecumbent hairs. Mesosoma ferruginous to ferruginous brown; head slightly darker; gaster darkest, usually brown to nearly black.

Male
Lattke (2004) - Metrics (n = 1): HL 0.88, HW 0.83, ML 0.47, SL 0.24, ED 0.38, WL 1.70 mm. CI 0.94, SI 0.29, MI 0.57, OI 0.46. Frons mostly areolate in frontal view with oval depression just anterad of median ocellus; with single, sharp ridge extending from depression to posterior end of clypeus. Clypeal shield with median longitudinal sulcus, mostly smooth with lateral ridges; frontal triangle large, smooth bottomed. Occipital lobes modest, subquadrate, not as developed as workers. Pronotum densely foveolate; mesopleuron foveolate, mesopleural suture well impressed; anepisternum with some strigulae, especially posterad. Metapleuron and propodeum densely foveolate. Mesonotum foveolate with some rugosity, scutellum densely foveolate.

Type Material
Lattke (2004) - Syntype workers: Birmania [Myanmar], Tienzo (Fea) (MCSN) [Examined].

Gnamptogenys bannana Xu and Zhang, 1996:55. Holotype worker: China, Yunnan, Menglun Town (Niu Yao) (SNUC) [Not examined]. New synonymy.

Ectatomma (Stictoponera) bicolor var. minor Forel, 1900:317. Syntype workers: Birmania [Myanmar] (MHNG) [Not examined]. Synonymized by Brown, 1950:245.

Additional References

 * Gobin, B., C. Peeters, and J. Billen. 1998a. Colony reproduction and arboreal life in the ponerine ant Gnamptogenys menadensis. Netherlands Journal of Entomology, 48:53-63.

Entomotaxonomia, 18:55-58.
 * Xu, Z. and W. Zhang. 1996. A new species of the genus Gnamptogenys (Hymenoptera: Formicidae: Ponerinae) from southwestern China.