Pachycondyla nakasujii, Yashiro, Toshihisa, Matsuura, Kenji, Guénard, Benoit, Terayama, Mamoru & Dunn, Robert R., 2010

Yashiro, Toshihisa, Matsuura, Kenji, Guénard, Benoit, Terayama, Mamoru & Dunn, Robert R., 2010, On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species, Zootaxa 2685, pp. 39-50 : 44-47

Pachycondyla nakasujii sp. nov.

( Figs 4 , 5 )

Worker: Measurements (mm) holotype (paratypes, n = 15): HW 0.83 (0.79–0.85); HL 0.91 (0.88–0.94); SL 0.87 (0.83–0.92); EL 0.15 (0.14–0.18); WL 1.42 (1.36–1.47); MW 0.60 (0.59–0.64); PW 0.52 (0.49–0.55). Structure. Head slightly longer than wide, weakly round-sided behind eyes, with weakly emarginate posterior margin in full-face view. Mandible with 6 larger and 4 smaller teeth on the masticatory margin, and with distinct basal fovea. Antenna long, scape surpassing the posterior margin of head by less than 1/4 of its total length in full-face view; all funicular segments longer than wide. Pronotal dorsum bluntly demarcated from lateral face; seen from above anterolateral corner round. Mesonotum distinctly demarcated from pronotum and propodeum by deep furrows, posteriorly weakly emarginate. Mesopleuron with a somewhat vestigially transverse groove. In profile propodeum demarcated by a distinct obliquely running suture from metapleuron; posterior face well demarcated from lateral face by a rather sharp ridge, but separation from dorsal face indistinct. Petiole thin and high, with weakly convex dorsal margin in profile; in posterior view petiolar scale round and slightly higher than wide, with convex dorsal margin. Sculpture. Dorsum of head minutely and densely punctate. Clypeus with much more superficial sculpture and shiny except for sculptured median portion. Mandible finely striatopunctate except for the area around apex and along mesal margin smooth with large sparse punctures. Dorsum of pronotum finely punctate; its lateral face and mesonotum with still finer punctation; mesopleuron almost smooth and shiny, with rugulae in lower area; upper portion of metapleuron punctate, with smooth interspaces, lower portion rugose, with smooth interspaces. Dorsolateral face of propodeum irregularly sculptured and matte, posterior face smooth except for margins and upper portion weakly sculputured. Petiole anteriorly micropunctate, posteriorly smooth. Gastral segments densely and weakly punctate evenly over the surface. Pilosity. Body covered with decumbent pubescence except for mesopleuron, metapleuron, and posterior faces of propodeum and petiole that are almost bare. Standing hairs sparse; gastral tergites 1 and 2 each with more than ten standing hairs. Coloration. Body dark brown to blackish; gaster slightly lighter than head and mesosoma. Antennal funiculus, mandible, subpetiolar process and legs yellowish brown to orangish.

Queen: Structure. Body distinctly larger than the worker, with the head width ranging from 0.86 to 0.87 mm. Eye much larger than the worker; EL = 0.22–0.25 mm. Ocelli small, ca. 0.07 mm in maximum diameter; distance between posterior ocelli greater 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. Sculpture. Body sculpture much as in the worker except for distinctly punctate metapleuron. Pilosity. Body covered with decumbent pubescence except for mesopleuron, and posterior faces of propodeum and petiole that are almost bare. Eye with short fine standing hairs. Mesosoma dorsally and gastral tergites with numerous long standing hairs. Coloration. Much as in the worker.

Male: Structure. Head including eyes much wider than long. Eye large; EL = 0.26–0.27 mm, strongly convex, mesally 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 small, ca. 0.08 mm in maximum diameter; distance between posterior ocelli much greater than that between anterior and posterior ocelli. Antenna long; scape twice as long as pedicel and 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 obtuse posterior tooth in profile. Sculpture. Head superficially micropunctate. Pronotum, mesoscutum, metanotum and metapleuron weakly sculptured; mesopleuron extensively smooth and strongly shiny; axilla coarsely rugose. Propodeum more strongly and densely sculptured, but on its posterior face sculpture somewhat weaker. Anterior and posterior faces of petiole densely and irregularly sculptured; posterior face very weakly sculptured and somewhat shiny. Gaster only superficially sculptured. Pilosity. Body covered with decumbent pubescence except for mesopleuron, and posterior faces of propodeum and petiole that are almost bare. Petiole extensively with dense obliquely standing short hairs on its anterior and lateral faces; subpetiolar process below with standing hairs. Outer margin of forewing and hindwing with dense short fringe. Coloration. Body brown to pale brown, with ivory white legs.

Type material examined. Holotype: worker, JAPAN, Okayama Prefecture, Okayama, Mt. Handayama, 34°41’47”N, 133°55’32”E, 22 m, 5 vi 2007, (coll. T. Yashiro). Paratypes: 3 queens and 8 workers from the same locality, 5 vi 2007, (coll. T. Yashiro); 3 males and 7 workers, JAPAN, Okayama Prefecture, Wake, Mt. Tenjinyama, 34°50’56”N, 134°07’47”E, 206 m, 4 vii 2008, (coll. T. Yashiro).

Type depository. The holotype (NSMT-I-Hym 51990) is deposited in the National Museum of Nature and Science, Tokyo. Paratypes are deposited in the National Museum of Nature and Science, Tokyo, Japan; the Osaka Museum of Natural History, Osaka, Japan; the Museo Civico di Storia Naturale “Giacomo Doria”, Genova, Italy; the Natural History Museum, London, England; and the Museum of Comparative Zoology, Harvard University, Cambridge, USA.

Additional material examined. 5 workers, JAPAN, Kanagawa Prefecture, Yokosuka, Hayama, 35°15’37”N, 139°36’23”E, 150 m, 7 v 2008, (coll. M. Yashiro); 1 queens and 5 workers, JAPAN, Kagawa Prefecture, Takamatsu, Nishiueta, 34°13’53”N, 134°4’38”E, 86 m, 14 x 2007, (coll. T. Yashiro); 1 queens and 5 workers, JAPAN, Fukuoka Prefecture, Tagawa, Mt. Hikosan, 33°28’52”N, 130°55’10”E, 994 m, 11 x 2007, (coll. T. Yashiro).

Etymology. This species is named in honor of Professor Emeritus Fusao Nakasuji, a notable Japanese entomologist and an authority on integrated pest management, who supervised the undergraduate and master's theses of one of the authors (Toshihisa Yashiro) at Okayama University.

Remarks. This species belongs to the Pachycondyla chinensis species complex. It is easily distinguished from the sympatric species P. chinensis in the worker by having a proportionally wider petiole (PI [Pronotal index: PW/HW x 100] = 60–64 in P. nakasujii , PI = 48–58 in P. chinensis ) ( Fig. 4 B,D) and in the male by having much darker coloration and the well developed mandibles ( Fig. 5 A–D). Moreover, the worker of this species is easily distinguished from another closely related species, P. luteipes , by having a proportionally wider petiole (PI = 60–64 in P. nakasujii , PI = 52–58 in P. luteipes ) ( Fig. 4 B,F) and a sculptured propodeum (largely smooth in P. luteipes ) ( Fig. 4 A,E).

Pachycondyla nakasujii nests in rotten wood or leaf litter on the ground. It is common in Honshu, Shikoku, and Kyushu, Japan, where it is sympatric with P. chinensis ( Fig. 6 ). Although P. nakasujii and P. chinensis are sympatrically distributed in temperate zones, P. nakasujii is rare in dry and disturbed area, where P. chinensis remains common. Both species have been observed to nest near termite nests frequently and to carry termites back to their nests as food.

Figures

FIGURE 4. Characters of worker propodeum and petiole. The left side of worker propodeum and petiole of P. nakasujii (A), P. chinensis (C) and P. luteipes (E), and the posterior face of worker petiole of P. nakasujii (B), P. chinensis (D) and P. luteipes (F) (Scanning electron microscopy photographs). Horizontal white arrow: PW. Also see Japanese Ant Database Group (2003).

FIGURE 5. Characters of male coloration and mandible of P. nakasujii (A, B), P. chinensis (C, D) and P. luteipes (E, F). Black arrows indicate the mandible.

FIGURE 6. Currently known distribution of P. nakasujii (A) and P. chinensis (B) in Japan. Each dot may indicate more than one site if they are located less than 20 km apart.