Mecyclothorax kokone, Liebherr, James K., 2013

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 67-68

55. Mecyclothorax kokone sp. n.

Diagnosis.

This smallest-bodied Tahitian Mecyclothorax - standardized body length 3.35 mm - is also diagnosable by the broadly flavous pronotal and elytral margins contrasted with rufopiceous discs, and small, little convex eyes (Fig. 31C); ocular ratio 1.41 (n = 2), ocular lobe ratio 0.75-0.76. The antennae are very short, the segments moniliform, with the antennomere 8 length 1.5 × its maximal breadth. Setal formula 2221. Head with broadly impressed frontal grooves, sinuously curved toward midline anteriorly, frons broadly convex between groove and antennal base; eye diameter anteriorly defined by antennal articulation crossing 12 ommatidia. Pronotum moderately transverse with broad base, MPW/PL = 1.22-1.24, MPW/BPW = 1.45; lateral margin straight anterad obtuse hind angle that is defined by triangular, raised expansion of lateral bead that houses basal pronotal seta articulatory socket, the hind angle therefore little more than a jag in the pronotal margin at the basal seta; median base slightly depressed relative to disc, rugosely wrinkled laterally, ~5 elongate punctures each side along margin with disc; anterior transverse impression shallow, broad, crossed by 3-4 very fine, indistinct wrinkles each side of midline; front angles rounded, not protruded, lateral marginal depression very narrow even at front angles, the edge beaded; laterobasal depression a broad expansion of lateral margin depression, crossed by transverse raised areas that also occur near base of lateral depression. Elytra subquadrate, slightly convex medially, flattened behind scutellum; striae 1-7 distinctly impressed, with elongate punctures in basal half, striae 1 + 2, 3, 4, and 5 continuous to basal groove; interval 8 broadly convex laterad stria 7 at elytral apex, only slightly raised above level of interval 7; lateral elytral setae 7 + 6. Metathoracic wings assessable due to breakage of left elytron from paratype; wing rudiment triangular with anterior subcostal margin 1.5 × length of truncate apical margin, the wing apex extended only to posterior margin of metanotum; alar surface ridged, with unmelanized indications of Sc + R and M veins, and a transverse budge more apically that seems not homologous with a vein as it does not reach the alar base. Microsculpture of frons a transverse mesh, sculpticell breadth 2 –4× length, with more transverse sculpticells in frontal grooves, sculpticells isodiametric on neck; pronotal disc with shallow transverse mesh, breadth 2 –4× length intermixed with transverse lines; elytral disc with well-developed transverse mesh, breadth 2 –4× length. Coloration of head rufous, more flavous behind eyes and near dark rufous frontoclypeal suture; antennomeres 1-3 flavous, 4-11 rufoflavous; pronotal disc each side of midline rufobrunneous with silvery reflection, lateral margins broadly flavous, anterior callosity and median base rufoflavous; elytral disc rufopiceous with purplish metallic reflection; base and humerus, lateral depression and ninth interval, apex of eighth interval and elytral apex apicad apical seta all flavous; sutural interval broadly rufoflavous basally, paler apically; femora flavous, tibiae flavous with brunneous cast.

Female reproductive tract. Bursa copulatrix relatively elongate, vagina of similar diameter and therefore not discernible (Fig. 33B), bursal length>3.0 × breadth compressed under cover slip; basal gonocoxite 1 narrow, with apical fringe of three setae placed laterally, and 6-8 setae lining the medial margin (Fig. 9B); apical gonocoxite 2 narrowly triangular, not extended laterally at base, rightly rounded apically, with two lateral ensiform setae, the basal seta of smaller diameter, and one dorsal ensiform seta; apical sensory furrow with two apical nematiform setae and two furrow pegs.

Holotype female (MNHN) labeled: French Polynesia: Tahiti Nui / Pito Hito el. 2000 m 2-VI- / 2006 lot 02 pyrethrin fog / 17°36.790'S, 149°27.842'W / E.M. Claridge // HOLOTYPE / Mecyclothorax / kokone / J.K. Liebherr 2013 (black-bordered red label).

Paratype: female specimen, reproductive tract dissected and left elytron removed (CUIC, 1).

Etymology.

The species epithet kokone is the Tahitian word for diminutive, and it signifies the very small body size of these beetles. Kokone is one of only a few Tahitian words ( Wahlroos 2002) to share the k sound with Tahitian’s close linguistic relative, Hawaiian; a fitting connection given the derivation of Tahitian and Hawaiian Mecyclothorax biotas from the same Australian stock ( Britton 1948; Liebherr 2012a).

Distribution and habitat.

This is another species known only from 2070 m elevation near the summit of Pito Hiti. As for the others, beetles of this species have been shown to inhabit arboreal moss on emergent vegetation through sampling using pyrethrin fog.