Mecyclothorax castaneus Perrault, 1986: 455

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 69

56. Mecyclothorax castaneus Perrault, 1986: 455

Identification.

Among the smaller-bodied members of the Mecyclothorax viridis group with elytral striae 1-5 continuously impressed to the elytral basal groove (Fig. 31), this species can be diagnosed by the rufopiceous dorsal body coloration (Fig. 31D) and the well-developed microsculpture: 1, head covered with regular transverse mesh across frons, neck with isodiametric sculpticells; 2, pronotal disc with densely packed transverse microsculpture, consisting of elongate transverse sculpticells and unconnected transverse lines; and 3, elytral discal intervals bearing gratelike transverse microsculpture consisting predominantly of transverse lines, with some areas including crossconnections resulting in an elongate transverse mesh. Summarizing the type series of two specimens ( Perrault 1986) plus six more specimens collected in 2006, only the 1986 female paratype unilaterally possesses a posterior dorsal elytral seta, the other elytron bearing only the anterior dorsal seta. Thus the most usual setal formula is 2211, a formula shared with Mecyclothorax paahonu , below. The male aedeagal median lobe is gracile and elongate, with an apicodorsal hooklike expansion (Fig. 30E). Standardized body length 3.8-4.1 mm.

Distribution and habitat.

In 1977, Perrault (1986) collected two specimens between 900 and 1100 m elevation on Mont Marau. In 2006 that elevational zone had become invaded with Albizia chinensis ( Fabaceae ) and was too dry for successful collecting. That year specimens were collected at 1275-1335 m elevation, through beating soft ferns and mossy Weinmannia branches, and via the use of pyrethrin fog on a tangled bank of dead ferns and a horizontal, moss-covered Weinmannia log.