Calyptomyrmex rectopilosus

Calyptomyrmex rectopilosus nests in rotting twigs and wood fragments on the floor of well-developed forests. Colonies are usually small, consisting of dozens of workers. This is one of only two Calyptomyrmex species currently known from the South-east Asian mainland (the other being Calyptomyrmex beccarii). (K. Eguchi pers. comm.; Eguchi, Bui and Yamane 2011).

Identification
Shattuck (2011) - 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.

Jaitrong & Yamane (2018) - The hairs on the head, mesosoma and gaster are fine (same width through entire length or slightly and gradually expanded distally) and blunt at the apex. The promesonotal hairs are almost as long as those on the head or slightly longer. The eye is small, with 2-3 ommatidia in the greatest diameter. The propodeum in profile is armed with a pair of moderately long, narrow teeth. The mandible is striate basally, essentially smooth apically. The rugae on the dorsum of the head are widely spaced, the underlying punctate surface is clearly visible and the rugae are essentially absent near the posterior margin. The upper portion of the mesosoma is covered with irregular, sinuous rugae that superimpose over the punctate background. The lower portions of the mesosoma, propodeum, petiole and postpetiole are punctate; the gaster is finely and is distinclty punctate and with a semi-matte appearance. The body colour is yellow-red with the gaster slightly darker.

Distribution based on Regional Taxon Lists
Oriental Region: Cambodia, Thailand, Vietnam. Palaearctic Region: China.

Nomenclature

 * . Calyptomyrmex rectopilosus Dlussky & Radchenko, 1990: 124, figs. 7, 8 (w.) VIETNAM.
 * Status as species: Shattuck, 2011a: 17 (redescription); Akbar & Bharti, 2015: 8 (in key); Jaitrong & Yamane, 2018: 134.

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.

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.

Jaitrong & Yamane (2018) - (n = 10): CFW 0.12–0.17, HL 0.63–0.76, HW 0.56–0.66, ML 0.56–0.66, MTL 0.26–0.35, PetL 0.12–0.17, PetW 0.25–0.30, PronW 0.43–0.59, SL 0.26–0.33, CI 86–90, PetI 160–225, SI 47–53.

Type Material
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.

References based on Global Ant Biodiversity Informatics

 * Dlussky G. M.; Radchenko A. G. 1990. The ants (Hymenoptera, Formicidae) of Vietnam. Subfamily Pseudomyrmicinae. Subfamily Myrmicinae (tribes Calyptomyrmecini, Meranoplini, Cataulacini). Pp. 119-125 in: Akimov, I. A.; Emelianov, I. G.; Zerova, M. D. et al. (eds.) 1990. News of faunistics and systematics. [In Russian.]. Kiev: Naukova Dumka, 184 pp.
 * Eguchi K.; Bui T. V.; Yamane S. 2011. Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), part I  Myrmicinae and Pseudomyrmecinae. Zootaxa 2878: 1-61.
 * Jaitrong W., and S. Yamane. 2018. A new species of the ant genus Calyptomyrmex Emry, 1887 (Hymenoptera: Formicidae: Myrmicinae) from Laos and new records of C. rectopilosus from Thailand and Hong Kong. Nat. Hist. Bull. Siam Soc. 62(2): 131-139.
 * Shattuck S. O. 2011. Revision of the ant genus Calyptomyrmex (Hymenoptera: Formicidae) in South-east Asia and Oceania. Zootaxa 2743:1-26.
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.