Pheidole yeensis Forel

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 107-110

Pheidole yeensis Forel

Figs. 30a-g, 32g, 32h

Pheidole sulcaticeps r. yeensis Forel , 1902: 179, 195. Emery 1921: 94 (subspecies of sulcaticeps ). Syntype: 1 major, "Birmah (Bingham) Ye Valley CCI 14" [Myanmar], MHNG, examined, designated as the lectotype [Fig. 32g, 32h].

Pheidole yeensis Forel . Binghami 1903: 252 (raised to species), Eguchi, Bui et al. 2005: 90 (checklist). Pheidole sp. eg-102. Yamane et al. 2003: 57.

Other material examined: S. China: Guangxi: Qinglongshan N.R., Longzhou [J. Fellowes]; Hong Kong: Tai Lung Farm, Sheung Shui, New Territory [Eg99-HK-37]; Hainan: Lumuwan N.R., 210 m alt., Danzhou [J. Fellowes], Limushan N.R., 620 m alt., Qiongzhong [J. Fellowes]. N. Vietnam: Bac Kan: Ba Be N.P., 22°24- 25'N, 105°37-38'E, <260 m alt. [Eg04-VN-167]; Thai Nguyen: My Yen Commune Forest, edge of secondary forest, Na Hau Village [Eg01-VN-138, -139, -142, -144]; Bac Giang: W. Yen Tu N.P. (= Tay Yen Tu N.P.), 21°11'N, 106°43-44'E, 150 m alt. [B&E04-2-1, -2, -3, -4, -5, -6, -7, -8], W. Yen Tu N.P., 190 m alt. [Eg03- VN-045, -048], W. Yen Tu N.P., 400 m alt. [Eg04-VN-075]; Quang Ninh: Ky Thuong N.R., 21°11'N, 107°07'E, 220 m alt. [Eg03-VN-187]; Vinh Phuc: Tam Dao N.P., <900 m alt. [Eg99-VN-072, -074, -075, - 077]; Ha Tay (misspelled as "Ha Tai"): Ba Vi N.P., 21°03'N, 105°22'E, ca. 400-550 m alt. [VN01-SKY-75]; Ninh Binh: Cuc Phuong N.P., 20°14'N, 105°36'E [Eg01-VN-202; Eg11vi05-02; Eg12vi05-21], Cuc Phuong N.P., 370 m alt. [Eg01-VN-166]. M. Vietnam: Nghe An: Lung Khung, 640 m alt., Pu Hoat [T.V. Bui], Ban Om, 550 m alt., Pu Hoat [T.V. Bui]. S. Vietnam: Dong Nai: S. Cat Tien N.P., <160 m alt. [Eg04-VN-515]. Thailand: Nakhonratchashima: nr. Sakaerat Environmental Research Centre [Eg01-TH-519, -520, -521, -541, -542, -556].

Worker measurements & indices: Major (n=5). - HL 2.01-2.09 mm; HW 1.77-1.83 mm; CI 85-89; SL 0.94-0.99 mm; SI 53-55; FL 1.55-1.61 mm; FI 87-88.

Minor (n=5). - HL 0.73-0.93 mm; HW 0.58-0.77 mm; CI 79-83; SL 0.86-0.97 mm; SI 126-149; FL 0.97-1.23 mm; FI 160-170.

Worker description

Major. - Head in lateral view strongly impressed on vertex; frons rugose longitudinally, with interspaces weakly punctured; vertex and dorsal and dorsolaeral faces of vertexal lobe reticulate or rugoso-reticulate, with enclosures weakly punctured; frontal carina well developed, partly overhanging antennal scrobe; median longitudinal carina of clypeus absent, inconspicuous or weak; hypostoma without conspicuous median and submedian processes, but with conspicuous lateral processes; outer surface of mandible smooth excluding its basal area, bearing short appressed hairs; antenna with a 3-segmented club; maximal diameter of eye longer than antennal segment X. Promesonotal dome in dorsal view transversely rugoso-reticulate, with enclosures weakly punctured, in lateral view with a low or inconspicuous mound on its posterior slope; humerus very weakly produced laterad; the dome at the humeri a little narrower than or almost as broad as at the bottom. Petiole (a little) longer than postpetiole (excluding helcium); petiolar node in rear view weakly concave mediodorsally; postpetiole not massive. First gastral tergite longitudinally rugoso-punctate entirely.

Minor. - Dorsum of head and mesosoma sparsely bearing relatively thick standing hairs; frons and vertex smooth or shagreened; dorsolateral part of head often rugoso-punctate weakly; preoccipital carina conspicuous dorsally and laterally; median part of clypeus largely smooth; median longitudinal carina of clypeus absent, or present but weak; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye almost as long as or shorter than antennal segment X. Promesonotal dome smooth entirely, or almost smooth dorsally and weakly rugoso-punctate dorsolaterally (and laterally); the dome in lateral view with a low mound on its posterior slope; humerus of the dome in dorso-oblique view not produced; mesopleuron, metapleuron and lateral face of propodeum well punctured. Petiole (a little) longer than postpetiole (excluding helcium); postpetiole relatively large but not massive.

Recognition: This species is characterized among Indo-Chinese species by the combination of the following features: in the minor dorsum of head and mesosoma sparsely bearing relatively thick standing hairs; in the major head in lateral view strongly impressed on vertex; in the major hypostoma at most with inconspicuous median and submedian processes; in the major and minor promesonotal dome in lateral view with a low mound on its posterior slope; in the major first gastral tergite longitudinally rugoso-punctate entirely.

This species is similar to P. planifrons Santschi among Indo-Chinese species (see under P. planifrons ).

Distribution & bionomics: Known from the Indo-Chinese subregion. This species is more common in open lands, tillage and gardens than in woody habitats, and nests in the soil. In N. Vietnamese rural areas this species and P parva are the most dominant Pheidole species. Prominent wall built with soil usually surrounds the nest entrance. Workers actively forage on the ground, and prey and/or scavenge on small invertebrates including other ground-foraging ants, such as Odontoponera denticulata .