Pheidole rabo Forel

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 80-84

Pheidole rabo Forel

Figs. 22a-g

Pheidole rabo Forel , 1913c: 28-30. Eguchi 2001a: 21-22 (lectotype designation, redescription of major & minor), Eguchi 2001b: 102-104 (redescription of major & minor), Eguchi, Bui et al. 2005: 90 (checklist), Eguchi, Yamane & Zhou 2007: 276-279 (reconfirmation of lectotype designation, redescription of major & minor). Lectotype: major, "No. 54a Maxwell's Hill Taiping Malacca (v. Buttel)" [W. Malaysia], MHNG, examined; paralectotypes: 1 major & 2 minors, same data as the lectotype, MHNG, examined; 2 queens, "No 643 Bandar Baroe Sumatra Malacca (v. Buttel)", MHNG, examined; original description also included syntype (s) from "Beras Tagi", not examined.

Pheidole concinna Wheeler , 1928: 13-16, junior primary homonym of P. concinna Santschi , 1910: 362. Lectotype: major, "Laokay, Indo-China, 2-22-25, F. Silvestri", MCZC cotype-20656, examined; paralectotypes: 1 major & 6 minors, same data as the lectotype, MCZC cotype-20656, examined.

Pheidole tsailuni Wheeler , 1929: 2, replacement name for Pheidole concinna . Eguchi 2001a: 30-32 (lectotype designation & redescription of major & minor), Yamane et al. 2003: 57 (checklist), Eguchi, Yamane & Zhou 2007: 276-279 (junior synonym of rabo ).

Other type examined: S. China: Hong Kong: Taipo Kau N.P., New Territory [Eg00-HK-014, -015, -16, - 23, -029]. Taiwan: Nantou: Wushe [S. Kubota's sample 82-A-J14], Lushan Hot Spring [S. Kubota's sample 80-E-G8, 80-E-G2]. Vietnam: Bac Giang: W. Yen Tu N.P. (= Tay Yen Tu N.P.), 21°10-11'N, 106°43-44'E, ca. 170 m alt. [Eg03-VN-080], W. Yen Tu N.P., ca. 190 m alt. [Eg03-VN-009, -019, -029], W. Yen Tu N.P., 240 m alt. [Eg03-VN-113]; Quang Ninh: Chua Yen Tu, 21°09'N, 106°43'E, 720-845 m alt. [Eg04-VN-051], Ky Thuong N.R., 21°09-11'N, 107°06-07'E, 160 m alt. [Eg03-VN-178], Ky Thuong N.R., 550 m alt. [Eg03- VN-231, -238]; Ha Tay (mislabeled as Ha Tai): Ba Vi N.P., 400-800 m alt., [Eg99-VN-113, -122; Eg01-VN- 229, -232; Eg02-VN-047, -058]; Ninh Binh: Cuc Phuong N.P., 20°14'N, 105°36'E [Eg01-VN-175, -188]; Nghe An: Pu Mat N.P. (Khe Kem Area, 18°58'N, 104°48'E, 255 m alt.) [Eg15iii06-01]; Dong Nai: S. Cat Tien N.P., <160 m alt. [Eg04-VN-766]. Thailand: Phang-nga: Khao Sok N.P., 08°55'N, 98°36'E [A. Schulz leg.]; Trang: Khao Chong Waterfall [Eg01-TH-724, -733]; Songkhla: Songkhla Univ. (Khao Kor Hong) [Eg01-TH-599], Ton Nga Chang, nr. Hat Yai [Eg01-TH-621]; Narathiwat: Bala area of Bala-Hala W.S. [Eg01-TH-687]. W. Malaysia: Selangor: Ulu Gombak [FI92MG-111, -203, -468, -511, -576, -577]; Johor: Kota Tinggi [FI92MKT-5]. E. Malaysia: Sabah: Gunong Rara [Eg97-BOR-588].

Worker measurements & indices: Major (data from Eguchi, Yamane & Zhou 2007). - HL 1.11-1.53 mm; HW 1.06-1.42 mm; CI 91-95; SL 0.49-0.59 mm; SI 42-49; FL 0.65-0.87 mm; FI 58-67.

Minor (data from Eguchi, Yamane & Zhou 2007). - HL 0.49-0.60 mm; HW 0.43-0.53 mm; CI 87-91; SL 0.45-0.53 mm; SI 100-108; FL 0.48-0.61 mm; FI 105-116.

Worker description

Major. - Head in lateral view not or very weakly impressed on vertex; frons longitudinally rugose; vertex rugoso-reticulate; dorsal and dorsolateral faces of vertexal lobe reticulate, with enclosures smooth to punctured; frontal carina absent or inconspicuous (present just as rugulae); antennal scrobe absent; median longitudinal carina on clypeus absent or conspicuous; hypostoma with low or inconspicuous median and well-developed submedian processes in addition to conspicuous (but sometimes reduced) lateral processes; outer surface of mandible (excluding area around the base) smooth or dimly rugose, sparsely with a (very) short appressed hairs; antenna with a 3-segmented club; maximal diameter of eye (a little) longer than antennal segment X. Promesonotal dome in lateral view at most with an inconspicuous mound on its posterior slope; humerus weakly produced laterad; the dome at the humeri as broad as or broader than at the bottom (or sometimes a little narrower than at the bottom). Petiole much longer than postpetiole (excluding helcium); postpetiole not massive. First gastral tergite weakly rugoso-punctate usually in its anterior 1/2 or more (at least around articulation with postpetiole).

Minor. - Dorsum of head punctured dorsally and laterally, and often overlain by weak rugoso-reticulation dorsally; preoccipital carina very weak or inconspicuous dorsally; median part of clypeus smooth, weakly punctured or weakly reticulate; median longitudinal carina absent, inconspicuous or weak; antenna with a 3- segmented club; scape usually exceeding posterior margin of head by almost the length of antennal segment II or more (but sometimes by the half length of II); maximal diameter of eye almost as long as or a little shorter than antennal segment X. Dorsal and lateral faces of mesosoma punctured; punctation on dorsum of promesonotal dome often overlain sparsely by weak rugulae; promesonotal dome in lateral view at most with an inconspicuous mound on its posterior slope; humerus in dorso-oblique view produced weakly or very weakly; propodeal spine elongate-triangular. Petiole (much) longer than postpetiole (excluding helcium); postpetiole not massive.

Recognition: This species is distinguishable among Indo-Chinese species by the combination of the following characteristics: in the minor head punctured dorsally and laterally; in the major frontal carina absent or inconspicuous (present just as rugulae); in the major antennal scrobe absent; in the major submedian processes of hypostoma well developed; in the minor maximal diameter of eye almost as long as or a little shorter than antennal segment X; in the minor scape exceeding posterior margin of head usually by almost the length of antennal segment II or more; in the minor mesosoma punctured; in the major and minor promesonotal dome in lateral view at most with an inconspicuous mound on its posterior slope.

This species is very similar to P parva , but distinguishable from the latter of which the minor has the following characteristics: scape exceeding posterior margin of head by less than half length of antennal segment II, or not reaching the posterior margin; maximal diameter of eye longer than antennal segment X.

Distribution & bionomics: Widely distributed in Indo-Chinese and Indo-Malayan subregions. This species inhabits usually well-developed forests but sometimes forest edges or bamboo forests, and nests under shelters (e.g., stones) or rarely in rotting logs on the ground.