Calyptomyrmex retrostriatus

This rarely encountered species has been collected from a submontane forest in Sarawak. Nothing more is known of its biology.

Identification
Hairs on head and body thin (essentially the same width along entire length and with blunt tips) and sculpturing on gaster a series of widely spaced longitudinal striations. This species is most similar to Calyptomyrmex lineolus in having thin body hairs and a heavily sculptured gaster, but differs in having the gaster entirely striate rather than consisting of a network anteriorly and striations posteriorly. Additionally, the body is body smaller (head width < 1.00mm) in the Malaysian-based retrostriatus while it is larger (head width > 1.20mm) in the Australian lineolus.

Distribution
This taxon was described from Borneo.

Nomenclature

 *  retrostriatus. Calyptomyrmex retrostriatus Shattuck, 2011: 19, fig. 13 (w.) BORNEO.

Holotype worker and 2 worker paratypes from G. Matang, near Kuching, Sarawak, May 1994, Löbl ; 3 worker paratypes from Gn Matang, 20km W Kuching, Sarawak, 800m, 13 May 1994, Löbl & Burckhardt, submontane forest.

Description
Worker description. Mandibles weakly striate basally, smooth distally (along masticatory margin). Eyes with 5–6 ommatidia in greatest diameter. Propodeum in lateral view with spines reduced to broad convexities and essentially absent. Propodeal lobes slightly thickened posteriorly. Node of petiole in profile slightly higher and narrower than postpetiole. In dorsal view the petiolar node slightly narrower than the postpetiolar node. Head indistinctly rugose, the rugae forming an indistinct network with the rugae more closely spaced anteriorly and more widely spaced posteriorly, and with the underlying surface finely but distinctly punctate. Mesosoma and petiolar and postpetiolar nodes with irregular, wavy rugae superimposed over an indistinctly punctate background. Gaster distinctly longitudinally striate. Hairs on head and body erect, uniform in diameter and with sharp or blunt tips. Clypeal fork with thin hairs only, the apical pair slightly thinner than the lateral pair. Colour red-brown, the antennae and legs slightly lighter.

Measurements. Worker (n = 4) - CFW 0.13–0.15; CI 112–114: HL 0.78–0.85; HW 0.87–0.96; ML 0.86–0.96; MTL 0.37–0.41; PetI 162–178; PetL 0.22–0.24; PetW 0.36–0.41; PronW 0.58–0.65; SI 50–51; SL 0.45–0.49.