Mecyclothorax gourvesi Perrault, 1978b: 146; 1988: 244

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 80

67. Mecyclothorax gourvesi Perrault, 1978b: 146; 1988: 244

Identification.

From the most similarly appearing Mecyclothorax gourvesioides , this species can be diagnosed by the convexity of the eighth elytral interval taking the form of a carina adjacent to stria 7, not an elongate, more broadly convex roll. The elytra are also narrower in this species, with the basal margins less extended laterally outside the humeral angles. At standardized body length 5.2-5.7 mm, individuals of this species are also larger than those of the former species. The head is glossy, with no indication of microsculpture on the frons or vertex, and only a narrow band of transverse-mesh microsculpture near the margin with the pronotum. The pronotal disc is covered with an obsolete transverse mesh, the sculpticells only visible outside areas of reflected light; sculpticell breadth 2 × length. The discal elytral intervals are lined with a well-developed transverse mesh, sculpticell breadth 2 –3× length. The male aedeagal median lobe has a robust, broad shaft, and is narrowly extended beyond the ostium to a spatulate, dorsoventrally expanded apex (Figs 36 E–I). The aedeagal internal sac bears a broad, diffuse ventral ostial microtrichial patch, a broadly spiculate dorsal ostial microtrichial patch, and a moderately elongate flagellar plate, length 0.43 –0.47× distance from parameral articulations to apical face (Figs 36G, H). This and Mecyclothorax acutangulus (Fig. 36B) are the two species in the group characterized by a spatulate median lobe apex, though the apex is not nearly so expanded here. Setal formula 2122.

Distribution and habitat.

This species is known from both Mont Marau and Mont Aorai; from 1125-1400 m elevation on the former, and 1210-1400 m on the latter. Various male specimens were dissected to verify conspecificity of populations on the two ridge systems, with observed variation precluding division into two species. There is variability in the dorsoventral expansion of the median lobe apex, with two specimens from Marau exhibiting a narrow apical extension and narrowly spatulate apex (Fig. 36F) to broadly spatulate apex (Fig. 36G). A third Marau specimen exhibits a broader apical extension with moderately expanded apex (Fig. 36E), a conformation shared with a specimen from Aorai (Fig. 36H). Finally, a fifth specimen from Mont Aorai has a very broad apical extension with moderately expanded apex (Fig. 36I), though the teneral nature of the specimen may have influenced its conformation when temporarily slide-mounted for photography.

Specimens have been collected from the rotten cambial layer under the bark of a dead Reynoldsia tree. They have been collected by beating Dicranopteris ferns, other soft ferns, or dead Cyathea tree fern fronds. Several were obtained through the use of pyrethrin fog applied to moss-covered Metrosideros , horizontal moss-covered logs, and banks of dead ferns. And two specimens were collected in a Malaise trap, indicating a penchant for climbing.