Pheidole indosinensis Wheeler, 2008

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 43-46

Pheidole indosinensis Wheeler stat.n.

Figs. 11a-h

Pheidole sulcaticeps subsp. indosinensis Wheeler , 1928: 10. Eguchi, Bui et al. 2005: 90 (checklist). Syntypes: 6 minors, "Yi Liang, Indochina, F. Silvestri leg." [China], MCZC cotype-20665, examined.

Other material examined: S. China: Guangdong: Dawuling N.R., Maoming [J. Fellowes], Nankunshan N.R., Top Gate, Longmen [J. Fellowes]; Hainan: Diaoluoshan N.R., Lingshui [J. Fellowes], Jianfengling N.R., Ledong [J. Fellowes]. N. Vietnam: Vinh Phuc: Tam Dao N.P., 21°27'N, 105°38'E, ca. 900 m alt. [Eg01- VN-108, -110, -111], Tam Dao N.P., 900-1100 m alt. [Eg99-VN-054, -057]; Ha Tay (misspelled as "Ha Tai"): Ba Vi N.P., 21°03'N, 105°22'E, ca. 1100 m alt. [Eg02-VN-032, -034], Ba Vi N.P., 1100-1200 m alt. [Eg99- VN-128].

Worker measurements & indices: Major (n=5). - HL 1.65-1.80 mm; HW 1.58-1.78 mm; CI 94-99; SL 0.91-0.99 mm; SI 55-59; FL 1.27-1.36 mm; FI 76-84.

Minor (n=5). - HL 0.70-0.78 mm; HW 0.59-0.67 mm; CI 83-86; SL 0.87-0.96 mm; SI 143-149; FL 0.89-1.00 mm; FI 149-157.

Worker description

Major. - Body deep yellowish-brown with paler appendages. Head in lateral view not or hardly impressed on vertex; vertexal lobes in full-face view relatively widely separated from each other; frons and anterior part of vertex rugose longitudinally-obliquely; posterior part of vertex and dorsal and dorsolateral faces of vertexal lobe rugoso-reticulate or reticulate; median longitudinal carina of clypeus usually conspicuous but sometimes very weak or inconspicuous; frontal carina relatively well developed; antennal scrobe present as a shallow impression; median process of hypostoma poorly developed or almost absent; submedian processes developed well; lateral processes conspicuous; antenna with a 3-segmented club; maximal diameter of eye shorter than or almost as long as antennal segment X (sometimes a little longer than antennal segment X). Promesonotal dome in dorsal view sparsely rugose or rugoso-reticulate transversely, with interspaces smooth, in lateral view with a low prominence/mound on its posterior slope; humerus hardly or very weakly produced laterad; the dome at the humeri as broad as or narrower than at the bottom. Petiole longer than postpetiole(excluding helcium); postpetiole not massive. First gasteral tergite smooth over the surface or very weakly punctured in its anterior 1/3.

Minor. - Body yellowish-brown. Frons and vertex smooth and shining or shagreened, or sometimes weakly rugoso-reticulate; dorsolateral and lateral face of head usually rugoso-reticulate dimly or weakly; median portion of clypeus smooth and shining, with a weak or conspicuous median longitudinal carina; preoccipital carina conspicuous dorsally and laterally; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye shorter than antennal segment X. Promesonotal dome largely smooth and shining, in lateral view usually with an inconspicuous mound on its gentle posterior slope; humerus in dorso-oblique view usually (but not always) produced very weakly; mesopleuron, metapleuron and lateral face of propodeum weakly punctured; propodeal spine elongate-triangular. Petiole longer than postpetiole (excluding helcium); postpetiole not massive.

Recognition: I was unable to find the type material of the nominotypical taxon of Pheidole sulcaticeps Roger in a possible depository (Zoologisches Museum an der Humboldt-Universitat zu Berlin). According to its original description (Roger, 1863a: 193-194) head of the major is in lateral view strongly impressed at the posterior 1/3 of its dorsum, and dorsum of "mesonotum [= a mound (prominence) on the posterior slope of promesonotal dome]" of the minor is in lateral view horizontal at the begining. These characteristics are not seen in P. sulcaticeps subsp. indosinensis which I recognised based on my examination of the type material of the subspecies. Thus, I here conclude that the two forms are different from each other at the species level, and raise the subspecies indosinensis to the species rank.

This species is characterized among Indo-Chinese species by a combination of the following characteristics: in the major dorsal and lateral faces of vertexal lobe rugoso-reticulate or reticulate; in the major frontal carina relatively well developed; in the minor preoccipital carina conspicuous dorsally and laterally; in the major submedian processes of hypostoma well developed; in the major posterior slope of promesonotal dome with a low prominence/mound; in the major and minor petiole longer than postpetiole. This species is similar to Pheidole elongicephala sp.n. and P ochracea sp.n. However, in the major of the latter two vertexal lobes in full-face view relatively close to each other; and submedian processes of hypostoma is usually (but not always) very small or inconspicuous.

Distribution & bionomics: Known from N. Vietnam and S. China. This species seemingly prefers woody habitats. Majors serve as repletes [Eg99-VN-128].