Mecyclothorax altiusculus (Britton)

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 36-37

21. Mecyclothorax altiusculus (Britton)

Thriscothorax altiusculus Britton, 1938: 104.

Mecyclothorax altiusculus , Britton 1948: 110; Perrault 1978b: 136; 1988: 232.

Identification.

Beetles of this species appear superficially similar to, and are distributed sympatrically with those of Mecyclothorax altiusculoides (Fig. 16D), but they exhibit pronotal lateral marginal depressions that are apically narrowed, and elytral lateral marginal depressions that are only narrowly reflexed (Fig. 17D). The discal elytral striae 1-6 are deeply and narrowly incised, and are lined with elongate punctures along their basal half, the punctures causing crenulations along the strial length. The eighth interval is finely carinate dorsad the posterior series of the lateral elytral setae, and gradually toward the elytral apex where the interval is broadly convex. The frons and vertex are covered with dense transverse lines that are progressively replaced by an isodiametric mesh near the pronotal juncture. The pronotal disc is glossy medially, with an elongate, partially confused transverse mesh laterally; and the discal elytral intervals are covered with isodiametric sculpticells arranged in transverse rows. The male aedeagal median lobe is very similar to those of Mecyclothorax paraltiusculus and Mecyclothorax pseudaltiusculus (Figs 18F, G), but has a slightly more slender shaft, and an apex with a more acute ventral tip, a flatter apical face, and a more ventrally curved ostial canal (Fig. 19A). Setal formula 2122; standardized body length 5.5-6.5 mm.

Distribution and habitat.

This species is known to occupy habitats on Mont Aorai from 1255 to 1940 m elevation. All associated ecological data place it in the axils of dead, decaying Freycinetia fronds, where is occurs microsympatrically with Mecyclothorax altiusculoides .