Aenictus yangi, Liu & Hita Garcia & Peng & Economo, 2015

Liu, Cong, Hita Garcia, Francisco, Peng, Yan-Qiong & Economo, Evan P., 2015, Aenictus yangi sp. n. - a new species of the A. ceylonicus species group (Hymenoptera, Formicidae, Dorylinae) from Yunnan, China, Journal of Hymenoptera Research 42, pp. 33-45 : 37-40

Aenictus yangi sp. n.

Figs 3A , 4A-D

Type material.

Holotype, pinned worker, China, Yunnan, Xishuangbanna, Man Sai village, 21°51'34.4"N, 101°16'39.6"E, 680m, young rain forest, leaf litter, 12.IIV.2013 (B. Blanchard, B. Guénard & C. Liu) (ISAS: CASENT0735503).

Paratypes, 14 pinned workers, China, Yunnan, Xishuangbanna, Man Sai village, 21°51'34.4"N, 101°16'39.6"E, 680m, young rain forest, leaf litter, 12.IIV.2013 (B. Blanchard, B. Guénard & C. Liu) (BMNH: CASENT0717204; CAS: CASENT0735506; CASENT0735508; HLMD: CASENT0735507; ISAS: CASENT0717203; CASENT0735495; CASENT0735496; CASENT0735498; MCZ: CASENT0735505; MHNG: CASENT0735504; NHMB: CASENT0735501; PUPAC: CASENT0735500; SKYC: CASENT0735499; THNHM: CASENT0735497).

Non-type material.

China, Yunnan, Xishuangbanna, Man Sai village, 21°51'34.4"N, 101°16'39.6"E, 680m, young rain forest, leaf litter, 12.IIV.2013 (B. Blanchard, B. Guénard & C. Liu).

Diagnosis.

Aenictus yangi differs from other South East Asian members of the A. ceylonicus group by the following combination of characters: head in full-face view distinctly longer than broad (CI 82-90); masticatory margin of mandible with seven teeth/denticles; antennal scapes relatively long (SI 76-86); metanotal groove noticeably present but weak; propodeal junction noticeably angulate with distinct tooth; subpetiolar process relatively elongate, subrectangular, and slightly projecting anteroventrally; propodeum laterally mostly smooth and shiny, weakly irregularly rugulose at base, and weakly reticulate-punctate near propodeal junction; petiole and postpetiole mostly smooth and shiny with lower portions reticulate-punctate.

Worker measurements

(N=17). TL 2.21-2.60; HL 0.51-0.57; HW 0.43-0.50; SL 0.33-0.42; ML 0.69-0.87; PL 0.17-0.20; CI 82-90; SI 76-86.

Worker description.

Head in full-face view distinctly longer than broad (CI 82-90), sides convex, posterior head margin straight to very weakly convex; occipital margin bearing a distinct carina. Antennal scapes relatively long (SI 76-86), extending beyond 2/3 of head length but not reaching posterior head margin. Frontal carinae relatively short and indistinct, reaching the level of posterior margin of torulus. Parafrontal ridges absent. Anterior clypeal margin weakly to moderately concave, not concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with large acute apical tooth followed by one medium-sized subapical tooth, one small denticle, one medium-sized tooth, two smaller denticles, and medium-sized basal tooth, reaching total of seven teeth/denticles; basal margin straight. Maximum width of gap between anterior clypeal margin and mandibles about 1.0 to 1.4 times broader than maximum width of mandible. Promesonotum convex dorsally and sloping gradually to metanotal groove; metanotal groove noticeably present but weak; mesopleuron relatively long, clearly demarcated from metapleuron by weak groove; metapleural gland bulla relatively large, its maximum diameter about 1.7 to 2.1 times longer than distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with feebly convex dorsal outline; propodeal junction noticeably angulate with distinct tooth; declivity of propodeum moderately concave and encircled by strongly developed rim. Petiole in profile higher than long, its dorsal outline strongly convex; subpetiolar process relatively elongate, subrectangular, and slightly projecting anteroventrally. Postpetiole slightly smaller than petiole, its dorsal outline strongly convex. Head including antennal scape entirely smooth and shiny. Mandibles predominantly unsculptured, smooth and shiny with weak, superficial striation basally. Promesonotum entirely smooth and shiny; mesopleuron and metanotal groove irregularly rugulose; propodeum laterally mostly smooth and shiny, weakly irregularly rugulose at base, and weakly reticulate-punctate near propodeal junction. Petiolar node and postpetiole mostly smooth and shiny with lower portions reticulate-punctate. Head and mesosoma dorsally with abundant erect to subdecumbent hairs. Head, mesosoma, and gaster usually reddish brown, always distinctly darker than yellow to light yellowish brown mandibles, antennae, petiole, postpetiole, and legs.

Etymology.

The new species is dedicated to Da-Rong Yang from the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences. We want to thank him for his great support of the first author’s studies in the area.

Distribution and ecology.

At present, the new species is only known from Xishuangbanna in southern Yunnan. The type locality is a tropical lowland rainforest situ ated at an elevation of around 550 m. The new species was only collected twice, both times through leaf litter extraction. Nevertheless, as for most Aenictus , we strongly suspect that A. yangi has a more hypogaeic lifestyle and might be more abundant in the soil stratum. The use of specific collection techniques that target subterranean army ants, such as subterranean oil baiting ( Weissflog et al. 2001), will likely yield additional material of this species. Unfortunately, due to the limited available material there is no additional information about its ecology.

Taxonomic notes.

The identification of A. yangi within the A. ceylonicus species group can be easily performed with the updated identification key provided above. The new species is morphologically most similar to A. baliensis Jaitrong & Yamane, 2013 (Bali), A. longicephalus Jaitrong & Yamane, 2013 (Lombok), A. minipetiolus Jaitrong & Yamane, 2013 (Lombok), and A. wiwatwitayai Jaitrong & Yamane, 2013 (Thailand). However, A. yangi can be immediately separated from these by the development of the metanotal groove, the shape of the propodeum and the subpetiolar process, and the sculpture on the mesosoma and waist segments (see Fig. 3 for details). Aenictus yangi can be easily separated from A. brevipodus Jaitrong & Yamane, 2013 (Thailand), and A. formosensis Forel, 1913 (Taiwan) by the number of mandibular teeth, shape of the head, the shape and punctate of petiole and postpetiole, and the shape of subpetiolar process.

Figures

Figure 3. Mesosoma and waist segments in profile (black arrows indicate metanotal groove and propodeal junction, black ellipse subpetiolar process). A A. yangi sp. n. B A. baliensis Jaitrong & Yamane C A. longicephalus Jaitrong & Yamane D A. minipetiolus Jaitrong & Yamane E A. wiwatwitayai Jaitrong & Yamane. Images except figure 3 A are from Jaitrong and Yamane (2013).

Figure 4. Aenictus yangi sp. n. (CASENT 0735503). A Body in profile B Body in dorsal view C head in full-face view D right mandible in frontal view.