Strumigenys morisitai

A rare species, known only from 2 records of specimens taken under stones in a rather open situation in Japan (Japanese Ant Image Database).

Barry Bolton (2000) had this to say about the peculiar mandible morphology of this species: "Even in a genus such as Pyramica (now combined with Strumigenys), where peculiarly shaped mandibles are commonplace, the utterly bizarre structure encountered in Strumigenys morisitai still promotes a sense of wonder. The shape evolved here is unique and its purpose impossible to determine. The relatively broad club-shaped basal portions of the mandibles contrast very strongly with the much narrower forceps-like apical portions, and these project down from the basal portions at a marked angle. Teeth are very small and restricted to the extreme apex, which is the only place on the apical portion where both blades fully engage."

Identification
Bolton (2000) – The only member of the Strumigenys morisitai-group. This species has such peculiar mandibular morphology that it could not be mistaken for any other.

Distribution based on Regional Taxon Lists
Palaearctic Region: Japan.

Nomenclature

 *  morisitai. Smithistruma morisitai Ogata & Onoyama, 1998: 284, figs. 16-18 (w.) JAPAN. Combination in Pyramica Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 124. See also: Bolton, 2000: 449.

Worker
TL 1.2-1.3 mm, HL 0.44-0.45 mm; HW 0.32-0.33 mm, CI 71-73, ML 0.14-0.15 mm, MI 32-33, SL 0.20-0.22, SI 61-69, PW 0.21-0.22 mm, WL 0.43-0.45 mm (3 measured).

Head distinctly larger than wide, with roundly convex sides posteriorly; posterior border emarginate with low occipital carina. Mandibles elongate, the exposed length about X 1.5 as long as clypeus; the shape peculiar; the shaft broadened towards apex and somewhat truncate or strongly bending downwards at anterior 1/3, forming an obtuse but distinct angled corner in lateral view, the subapical portion slightly concave in lateral view, and forming shallow space in full face view, when the mandibles are closed. Clypeus as long as wide or slightly longer than wide; anterior margin narrowly convex. Antennae 6-segmented; scape simply broadened at basal 1/3, not forming an angulate elbow; apical segment long, as long as scape and longer than the rest of funicular segments together; subapical segment as long as 2nd antennal segment. Eyes small but distinct, consisting of 4 facets, situated at posterior 2/5.

Pronotum weakly marginate anteriorly, anterior margin narrowly rounded in dorsal view; metanotal groove very weakly impressed. General shape of mesosoma similar to that of Strumigenys incerta, without angulate pronotal humeri; dorsal outline gently convex; posterior margin of propodeum with thin lamellate appendages and with dorsal spiniform processes. Spongiform appendages on petiole and postpetiole developed. Hairs on body narrow scale-like and appressed, on gaster simple and decumbent. Body color brownish yellow.

Bolton (2000) - TL 1.7, HL 0.44, HW 0.32, CI 73, ML 0.13-0.16, MI 30-35, SL 0.20-0.22, SI 63-69, PW 0.20-0.21, AL 0.42-0.45 (2 measured). In full-face view the club-like basal portion of the mandible with numerous appressed short spatulate hairs, these hairs slightly shorter and somewhat more dense than those on the clypeus. Entire dorsum of head finely reticulate-punctate, without standing hairs of any form; the flagellate apicoscrobal is the only specialised hair on the head. Eye small, of only 4 ommatidia in total and just visible in full-face view. Dorsal alitrunk, declivity of propodeum and dorsum of petiole finely reticulate-punctate. Mesopleuron and metapleuron smooth and shining. Basigastral costulae short but sharply defined, occurring across the width of the first gastral tergite, without a central costula-free area. Postpetiole disc and gaster smooth.

Type Material
Bolton (2000) - Holotype and paratype workers, JAPAN: Higashi, Kunigami-gun, Okinawa I., 14.xi.1975 (T. Abe) [examined].

Etymology
The species name is for the memory of the late Dr. Masaaki Morisita.

Determination Clarifications
The species was placed under a separate unnamed genus in MSJ (1988) and Ogata & Onoyama (1992) and was treated with the Japanese name, Kibaore-uroko-ari. It also corresponds to “unnmaed new genus? sp.” of Onoyama (1976).

References based on Global Ant Biodiversity Informatics

 * Ogata K. and Onoyama K. 1998. A Revision of the Ant Genus Smithistruma Brown of Japan, with Descriptions of Four New Species (Hymenoptera: Formicidae). Entomological Science 1: 277-287
 * Terayama M., S. Kubota, and K. Eguchi. 2014. Encyclopedia of Japanese ants. Asakura Shoten: Tokyo, 278 pp.
 * 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., Y. Harada, and K. Eguchi. 2013. Classification and ecology of ants. Natural history of ants in Southern Kyushu. 200 pages
 * 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.