Tetramorium ocothrum, Bolton, B., 1979

Bolton, B., 1979, The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Malagasy region and in the New World., Bulletin of the British Museum (Natural History) Entomology 38, pp. 129-181 : 176

Tetramorium ocothrum sp. n.

(Fig. 57)

Holotype worker. TL 2.9, HL 0.64, HW 0.56, CI 87, SL 0.47, SI 84, PW 0.42, AL 0.70.

Antennae with 12 segments. Mandibles delicately longitudinally striate. Anterior clypeal margin convex and entire. Frontal carinae reaching a level about halfway between posterior margins of eyes and occipital corners, weak throughout their length, no stronger than the cephalic sculpture with which they merge posteriorly. With head in full-face view the sides evenly convex, the occipital margin transverse, not concave medially. Eyes moderate, maximum diameter 0.12, about 0.21 x HW, situated in front of the midlength of the sides. Dorsal alitrunk evenly convex in profile, in dorsal view the pronotal corners rounded. Propodeal spines short, narrow and spiniform, slightly longer than the acute triangular metapleural lobes. Petiole in profile with a long, downcurved anterior peduncle and a low dome-shaped node with broadly rounded antero- and posterodorsal angles and an evenly convex dorsum. In dorsal view the petiole node subglobular, slightly broader than long. Postpetiole with an anterior peduncle which is narrower than the node itself, the whole segment longer than broad. Dorsum of head covered with a mass of fine, irregular, dense confused regulation, the interspaces finely punctulate. Dorsal alitrunk with a fine open rugoreticulum. Petiole and postpetiole unsculptured dorsally but the former with lateral traces of faint punctulation. Gaster unsculptured. All dorsal surfaces of head and body with numerous elongate fine hairs but the dorsal (outer) surfaces of the hind tibiae only with short, appressed pubescence. Colour black.

Holotype worker, Borneo: Sarawak, 4 th Division, Gunong Mulu Nat. Pk, RG. S .. Expd. Long Pala, lowl. rainfor., on tree trunk, 14. X. 1977 (B. Bolton) (BMNH).

A species of the tonganum-group, most closely related to tonganum itself and running out with that species in the key (Bolton, 1977: 77). The two are quickly separable by colour, tonganum being yellowish brown or mid-brown whilst ocothrum is black. Apart from this the eyes of tonganum are slightly larger (0.24 - 0.27 x HW) and the cephalic sculpture is more regular, not so nearly disorganized in appearance as in ocothrum .