Pachycondyla nigrita (Emery, 1895)

Yamane, S., 2007, Pachycondyla nigrita and related species in Southeast Asia., Advances in ant systematics (Hymenoptera: Formicidae): Homage to E. O. Wilson - 50 years of contributions. (Memoirs of the American Entomological Institute 80), pp. 650-663 : 653-655

Pachycondyla nigrita (Emery, 1895)

Figures 6, 17,18

Ponera nigrita Emery , 1895: 459 (w) examined.

Euponera (Brachyponera) nigrita : Emery, 1900: 668.

Brachyponera nigrita : Bingham, 1903: 102.

Pachycondyla nigrita : Brown in Bolton, 1995: 307.

Worker (redescription of a syntype of Ponera nigrita Emery ). Measurements (mm): Body length in fully extended posture ca. 6; HW 1.05; HL 1.14; SL 1.14; EL 0.21; MSL 0.10. SL / HL 1.00, Number of ommatidia along longest axis of eye 12.

Antennal scape long, surpassing the posterior margin of head by more than 1 / 4 of its total length; segments 3 - 7, 11 distinctly longer than wide; segments 8 - 10 only slightly longer than wide (relative length of funicular segments much longer than in those of P. luteipes ). Mandibular fovea distinct. Lateral face of mesosoma very weakly sculptured or shining; lateral face of propodeum well demarcated from metapleuron by a suture, somewhat distinctly microsculptured and relatively mat. In profile petiole thick; its lower margin longer than lower margin of metapleuron.

Queen. The following description is based on specimens from Doi Suthep, N. Thailand. Structure. Body distinctly larger than the worker, with the head width ranging from 1.04 to 1.06 mm. Eye much larger than in the worker (ca. 0.28 mm long and with ca. 22 ommatidia along the long axis). Distance between posterior ocelli longer than that between anterior and posterior ocelli. Mesopleuron above always with a distinct transverse groove. Compared with the worker, petiole relatively thin, seen from above almost lacking dorsal flat portion. Body sculpture much as in the worker. Mesopleuron and metapleuron smooth and shining; in one specimen from Taiwan posterior face of propodeum and petiole also smooth medially, and mesopleuron partly and metanotum densely punctate. Pilosity. Body covered with decumbent pubescence except on mesopleuron and metapleuron where pubescence is absent or very sparse. Eye with short fine standing hairs. Mesosoma dorsally and gastral tergites with very sparse standing hairs; long hairs on tergites almost confined to their posterior margins; sternites with more long standing hairs on the disc. Outer margin of forewing with dense short fringe; outer and posterior margins of hindwing fringed with longer hairs. Coloration much as in the worker.

Male. Description based on the specimens from the same series as the queen. Structure. Head including eyes much wider than long. Eyes very large (maximum diameter ca. 0.40 mm) with outer margin strongly convex and inner margin weakly emarginate. Clypeus transverse with anterior and posterior margins truncate; labrum anteriorly produced as a narrow lobe. Mandible long and fragile, not opposable, basally wide and suddenly narrowed toward bluntly pointed apex. Ocelli relatively large; distance between posterior ocelli slightly longer than their diameter, and as long as ocello-occipital distance; antenna long; scape (segment 1) twice as long as segment 2 and slightly shorter than segment 3. Pronotum short; mesoscutum large, with weak notauli and sharp parapsidal lines; mesopleuron large, with a wide transverse furrow which is striate on the bottom; scutellum dorsally convex with an anterior transverse zone which is much lower than the main disc; axilla extensively concave; metanotum short. Propodeum rounded; dorsal, lateral and posterior faces not clearly differentiated. Petiole relatively low, in profile rather strongly narrowed above, seen from back almost as wide as high, with dorsal margin almost straight; subpetiolar process flat, with acute posterior tooth in profile. Sculpture. Head superficially micropunctate. Sculpture on pronotum, mesoscutum, metanotum and metapleuron still weaker; mesopleuron extensively smooth and strongly shining; axilla coarsely rugose. Propodeum more strongly and densely sculptured, but on its posterior face sculpture somewhat weaker. Anterior face of petiole mat; posterior face weakly shining. Gaster only superficially and sparsely punctate and somewhat shining. Pilosity similar to that in the queen. Mesopleuron, metapleuron and posterior face of petiole almost hairless. Petiole extensively with dense obliquely standing short hairs on its anterior and lateral faces; subpetiolar process below with standing hairs. Fringe on wings as in the queen. Coloration. Body brown to pale brown, with ivory white femora and tibiae; tarsi especially fore tarsus darker. Scape and pedicel yellowish; other segments dark brown.

TYPE MATERIAL

Worker, Carin Ghecu, Myanmar, 1300 - 1400 m L. Fea II-III 88 [printed] / Ponera nigrita Emery [handwritten] / Emery [handwritten] / Collect. G. Mayr [printed] / nigrita [handwritten] det Emery [printed] (examined).

ADDITIONAL MATERIAL

THAILAND. 2 w, Doi Inthanon N. P. (HQ, 1800 m alt.), Chiang Mai Prov., 20 viii 1998, Sk. Yamane; 1 w, Doi Ang Kang (HQ, 1300 m alt.), Chiang Mai Prov., 21 viii 1998, Sk. Yamane; 10 w, Doi Suthep N. P., Chian Mai Prov., 21 - 22 xii 1997, F. & Sk. Yamane; 12 w, same loc., 18 viii 1998, H. Okido & Sk. Yamane; 5 w, 1 m, same loc. & date, H. Okido (TH 98 - H 006); 10 w, 2 q, 8 m, same data, Sk. Yamane (TH 98 - SKY- 06 & - 07). VIETNAM. 30 w, Cuc Phuong N. P., Nho Quan Distr., 10 - 12 viii 1998, Sk. Yamane; 3 w, same loc., 9 xi 2001, Sk. Yamane; 10 w, same loc. (320 m alt.), 10 xi 2001, K. Eguchi (Eg 01 - VN- 189); 8 w, Bavi N. P. (670 m alt.), Hatai Distr., 12 xi 2001, K. Eguchi (Eg 01 - VN- 227); 11 w, same loc., Sk. Yamane (VN 01 - SKY- 96); 3 w, same loc. (1100 m alt.), 19 iv 2002, K. Eguchi (Eg 02 - VN- 037); 18 w, Tam Dao (900 - 1240 m alt.), Vinh Phuc Prov., 9 viii 1998, Sk. Yamane; 1 q, same loc., 8 viii 1998, H. Okido; 1 w, Na Xan (500 m alt.), Nghe An Prov., 14 iv 1999, T. V. Bui. TAIWAN. 2 w, 1 q, Wulai, Taipei Hsien, 2 viii 1981, M. Terayama; 10 w, Fushan, Taipei Hsien, 22 - 23 ix 1997, Sk. Yamane.

REMARKS

The worker specimens from Doi Suthep, Chiang Mai, N. Thailand agreed well with the type material. This species is very similar to P. pilidorsalis that occurs in Borneo and the southern part of the Malay Peninsula. The former is distinguished from the latter by 1) more weakly sculptured posterior faces of propodeum and petiole (W), 2) fewer and shorter standing hairs on mesosoma and gastral tergites 1 and 2 (W, Q), 3) frequent lack of transverse groove on mesopleuron (W), and 3) much larger body size (Q).

P. nigrita shows variation in sculpturation on the mandible and propodeum in the worker. Striation and punctation in these parts tend to be stronger and more extensive in the specimens from N. Vietnam; in some specimens the major portion of the mandible is densely striate, and the lateral and posterior faces of the propodeum are extensively and rather coarsely striate or irregularly sculptured.

The subspecies P. nigrita nigritella (Starcke, 1930) from Sumatra may not be a race of P. nigrita , since according to the original description the body size and eye size are smaller for P. nigrita , and head is relatively long (HL / HW 1.14 for nigritella vs. 1.10 for typical nigrita ). Starcke himself (1930) suggested that nigritella is closely related to Brachyponera nigrita chinensis , which is now given specific status (Brown, 1958).