Vollenhovia okinawana

This species is widely distributed on Okinawa Island, nesting in decaying wood in forests. The females are winged. Vollenhovia yambaru, which produces ergatoid females and workers identical to those of V. okinawana, is found in the native forests of northern Okinawa. 

Identification
Terayama & Kinomura (1997) - Very similar to Vollenhovia benzai. However, it is distinguished from the latter by the shape of the postpetiole which is highest at posterior 1/3 and concave posterodorsal margin in the female and worker (highest at midlength and convex posterodorsal margin in benzai).

Distribution based on Regional Taxon Lists
Palaearctic Region: Japan.

Nomenclature

 *  okinawana. Vollenhovia okinawana Terayama & Kinomura, 1997: 4, figs. 4, 8 (w.q.) JAPAN.

Worker
Holotype. HL 0.53 mm; HW 0.45 mm; SL 0.31 mm; CI 85; SI 69; WL 0.63 mm; PL 0.24 mm; PH 0.21 mm; DPW 0.15 mm; TL 2.1 mm.

Head longer than wide, with subparallel sides and weakly concave posterior margin in frontal view. Mandibles with 7 teeth; basalmost tooth minute. Clypeal carinae subparallel. Antennae with 12 segments; scape 0.58 x head length. Eyes 0.13 mm in diameter.

Dorsum of promesonotum almost straight in profile; metanotal groove not incised dorsally; posterodorsal comer of propodeum dully angulate, without tooth in profile.

Petiole as long as high, with convex dorsal outline in profile; anterodorsal and posterodorsal corners not forming angle. Subpetiolar process low and small; its thin lamellar wall ca. 0.04 mm in height. Postpetiole slightly longer than high, highest at posterior 1/3 in profile; posterodorsal margin concave.

Head shagreened with relatively large coarse punctures; space between punctures less than 0.5 x their own diameters; dorsum of alitrunk punctated with unsculptured longitudinal band medially; mesosoma, propodeum and petiole reticulate; sculpture on petiole weaker than that on propodeum; postpetiole smooth in most part: gaster and legs smooth and subopaque.

Color: reddish brown; mandibles, antennae, and legs yellowish brown; frons without dark brown spot.

Queen
Paratype. HL 0.60 mm; HW 0.56 mm: SL 0.35 mm; CI 94: SI 62; WL 0.88 mm: PL 0.25 mm; PH 0.29 mm; DPW 0.18 mm; TL 2.6 mm. (one measured).

Head slightly longer than wide. with slightly concave posterior margin in frontal view; eyes 0.15 mm in diameter: ocelli forming right triangle.

Alitrunk 0.45 mm in maximum dorsal width; dorsum of pro- and mesonotum coarsely punctated, with smooth interspaces; mesonotum with an unsculptured longitudinal band medially; propodeum without tooth.

Petiole higher than long, with convex dorsal outline in profile. Subpetiolar process low and small. Postpetiole highest at posterior 1/3, with concave posterodorsal margin in profile.

Forewings 0.60 mm in length. Color: reddish brown; ocellar triangular area dark brown; frons without large brown spot.

Variation. Five paratype workers with the following measurements and indices: HL 0.48-0.49 mm; HW 0.45 mm; SL 0.29-0.30 mm; CI 92-95; SI 63-64; WL 0.60-0.63 mm; PL 0.20-0.24 mm; PH 0.19-0.20 mm; DPW 0.15-0.16 mm; TL 2.0-2.2 mm.

Eye diameter varies from 0.12 to 0.13 mm. In some specimens the basalmost tooth of mandibles is obscure.

Type Material
Holotype. Worker, Gushiken. Notobu, Okinawajima, Okinawa Pref., 1.1.1985, K. Yamauchi leg. Paratypes. 1 female, 6 workers, same data as holotype; 1 female, 2 workers, Nakijin, Motobu, Okinawa-jima. Okinawa Pref., Xll.1990, K. Yamauchi leg.; 8 females, 21 workers. Fuku-gawa, Okinawa-jima, Okinawa Pref., 31.XII.1984, K. Yamauchi leg.

Type depository. The holotype and some paratypes are deposited in the Museum of Nature and Human Activities, Hyogo, and the other paratypes are in the National Institute of Agro-Environmental Sciences, Tsukuba. and National Science Museum, Tokyo.

Etymology
The specific epithet refers to the type locality.

Determination Clarifications
orresponds to Vollenhovia sp. 4 ("Okinawa-umematsuari" in Japanese) in Terayama and Yamauchi (1992).

References based on Global Ant Biodiversity Informatics

 * Fukumoto S., Sk. Yamane, and M. Hira. 2016. Records of ants from Yoro-Shima, Amami Gunto, Japan (Hymenoptera, Formicidae). Nature of Kagoshima 42: 461–464.
 * Kobayashi K., H. Tamura, M. Okamoto, E. Hasegawa, K. Ohkawara. 2012. Phylogenetic relationships among populations of Vollenhovia ants, with particular focus on the evolution of wing morphology. Annals of the Entomological Society of America 105(3):454-461.
 * Terayama M., S. Kubota, and K. Eguchi. 2014. Encyclopedia of Japanese ants. Asakura Shoten: Tokyo, 278 pp.
 * Terayama M.; Kinomura, K. 1997. Taxonomic studies of Japanese Formicidae, part 3. Genus Vollenhovia Mayr. Nature & Human Activities 2:1-8.
 * Yamane S. 2016. How many species of Ants in Amami Islands? (in Japanese). Part 2, chapter 1 in How many species of Ants in Amami Islands? Pp. 92-132.
 * Yamane S., S. Ikudome, and M. Terayama. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp, 138-317.
 * Yamane S.; Ikudome, S.; Terayama, M. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp138-317.