Mecyclothorax ninamu, Liebherr, James K., 2013

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 65-67

53. Mecyclothorax ninamu sp. n.

Diagnosis.

Among the five species in the Mecyclothorax viridis group that exhibit smaller body size, standardized body lengths 3.3-4.2 mm (Fig. 31), this species is characterized by a very dark, glossy dorsal surface with metallic blue reflection. The head, pronotal disc, and discal elytral intervals lack distinct microsculpture, with areas of obsolete, elongate transverse mesh visible over portions of each somite. Only the first and seventh elytral striae are deeply impressed apically, with the second stria broader and much less defined. Setal formula 2221; standardized body length 3.5-4.0 mm. Head with narrowly incised, subparallel frontal grooves, the mesal surface with transversely radiating wrinkles inside anterior supraorbital seta, grooves broader, quadrately depressed at frontoclypeal suture; eyes moderately convex but with dorsal margin convexly convergent, ocular ratio 1.49-1.55, ocular lobe distinctly protruded from gena, ocular lobe ratio 0.82-0.89; antennae short, submoniliform, antennomere 8 length 1.75 × maximal breadth. Pronotum cordate, lateral margins distinctly convergent anterad right to slightly obtuse, protruded hind angles, MPW/BPW = 1.49-1.56 (n = 5), and moderately transverse, MPW/PL = 1.19-1.24; median base only slightly depressed relative to disc, 16-19 deep, rounded punctures each side, the punctures more elongate along juncture with disc; anterior transverse impression broad, shallow, medially crossed by indistinct longitudinal wrinkles in some individuals, defined anteriorly by upraised, nearly flat anterior callosity; front angles not protruded, rounded behind; lateral marginal depression narrow throughout length, edge beaded, broadened inside front angle; laterobasal depression a narrow oblique continuation of lateral marginal depression, surface punctate, the depression defining a triangular raised area with the basal pronotal seta. Elytra broadly ovate, convex, sides distinctly sloped to vertical at lateral marginal depression; humerus broadly angulate laterad the evenly curved basal groove; striae 1-7 shallow but evident, continuous, obsolete basally and not reaching basal groove, indistinctly punctate in basal half, smooth and deeper apically; lateral marginal depression broadest at humerus, narrow with beaded margin posteriorly; interval 8 more convex than intervals 2 or 7 at elytral apex, surface broadly convex both dorsally and laterally; lateral elytral setae 7 + 6; the lone apical elytral seta in outer half of terminally fused striae 3 + 7 near apical terminus of interval 8. Coloration of head rufopiceous with silvery reflection, mandibles rufoflavous; antennomeres 1-3 rufoflavous, 4-11 with rufous cast; pronotal disc rufopiceous with indistinct blue-green reflection, only the median base paler, rufobrunneous near margin; elytral disc rufopiceous with more distinct blue-green reflection, lateral marginal depression narrowly rufobrunneous at humerus, rufoflavous apically; femora and tibiae contrastedly pale, rufoflavous, the tibiae with brunneous cast.

Male genitalia. Aedeagal median lobe curved dorsally, apex broadened dorsoventrally with broad, flat apical face (Fig. 30C), the apical configuration an exaggeration of that observed in males of Mecyclothorax viridis (Fig. 30D); flagellar plate relatively elongate for the short median lobe, length 0.52 × distance from parameral articulations to apical face.

Female reproductive tract. Bursa copulatrix elongate, symmetrical and only slightly narrower than vagina in unstretched configuration (Fig. 33A), bursal + vaginal length 3.7 × bursal breadth when flattened under cover slip; basal gonocoxite 1 short, broad, with apical fringe of four setae and 6-8 smaller setae along medial margin (Fig. 9A); apical gonocoxite 2 stout, moderately expanded basally with arcuate lateral margin, and bearing two subequal lateral ensiform setae, a dorsal ensiform seta; apical sensory furrow with two apical nematiform setae and two furrow pegs.

Holotype male (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 / ninamu / J.K. Liebherr 2013 (black-bordered red label).

Allotype female (MNHN) labeled: French Polynesia: Tahiti Nui / Pito Hito el. 2070 m 2-VI- / 2006 lot 01 pyrethrin fog / 17°36.813'S, 149°27.842'W / E.M. Claridge // HOLOTYPE / Mecyclothorax / ninamu / J.K. Liebherr 2013 (black-bordered red label).

Paratypes: 3 paratypes labeled as the holotype (CUIC, 2; EMEC, 1).

Etymology.

The Tahitian word nīnamu means blue as in the blue color of a lagoon, and signifies the metallic dorsal coloration of these beetles.

Distribution and habitat.

This species inhabits the summit area of Pito Hiti from 2000-2070 m elevation, with specimens collected from moss-covered vegetation through the application of pyrethrin fog.