Calyptomyrmex rectopilosus

This is one of only two Calyptomyrmex species currently known from the South-east Asian mainland (the other being Calyptomyrmex beccarii). It has been encountered a number of times in Vietnam and is known to nest in rotten twigs and small fragments of rotten wood in well-developed forests (K. Eguchi, pers. comm.).

Identification
Hairs on head and body thin (essentially the same width along entire length, or only slightly and gradually expanded distally, and with blunt tips), propodeum armed with moderately long, narrow spines, petiolar node leaning slightly posteriorly, the anterior face rounding into the dorsal face, in dorsal view broader than long; rugae on dorsum of head widely spaced, the underlying punctate surface clearly visible, the rugae fading posteriorly and essentially absent near the posterior margin. This species can be separated from others in this region by the thin body hairs, relatively long, narrow propodeal spines and the configuration of the cephalic sculpturing.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 *  rectopilosus. Calyptomyrmex rectopilosus Dlussky & Radchenko, 1990: 124, figs. 7, 8 (w.) VIETNAM. See also: Shattuck, 2011: 17.

Holotype worker from "Archipelago Baitylong, Isl. Dongho", Quang Ninh Prov., Vietnam. This island is also known as Do Dông Khoa, Ba Mùn Island and Cao Lô Island (and probably other names) and is located approx. 100km ENE Hi Phòng at approx. 21º00’N 107º35’E.

Description
Worker description. Mandibles striate basally, essentially smooth apically. Eyes small, with 2–3 ommatidia in greatest diameter. Propodeum in lateral view armed with moderately long, narrow spines. Propodeal lobes uniform in thickness. Node of petiole in profile higher and narrower than that of postpetiole. In dorsal view the petiolar node similar in width to postpetiolar node. Head with widely spaced and indistinct rugae anteriorly, fading to essentially absent posteriorly, with the entire surface distinctly punctate. Upper section of mesosoma with irregular, wavy rugae superimposed over a punctate background; lower section of mesosoma (above legs), propodeum, petiole and postpetiole punctate. Gaster finely and indistinctly punctate and with a semi-matte appearance. Hairs on head and body erect, uniform in diameter and with sharp or blunt tips. Clypeal fork with short, thickened hairs basally and thin, elongate hairs distally. Colour yellow-red, the gaster slightly darker.

Measurements. Worker (holotype) - CFW 0.10; CI 97; HL 0.63; HW 0.60; ML 0.57; MTL 0.25; PetI 163; PetL 0.12; PetW 0.20; PronW 0.40; SI 57; SL 0.35.

Additional References

 * Dlussky, G.M. & Radchenko, A.G. (1990) The Ants (Hymenoptera, Formicidae) of Vietnam. Subfamilies Pseudomyrmicinae and Myrmicinae (tribes Calyptomyrmecini, Meranoplini and Cataulacini), pp. 119–125 in Akimov, I.A., Emelianov, I.G. & Zerova, M.D. (eds.). News of Faunistics and Systematics, Kiev (Naukova Dumka) [in Russian].
 * Shattuck, S.O. (2011) Revision of the ant genus Calyptomyrmex (Hymenoptera: Formicidae) in South-east Asia and Oceania. Zootaxa, 2743, 1-26.