Mecyclothorax bicoloratus, Liebherr, James K., 2015

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 276-277

Taxon classification Animalia Coleoptera Carabidae

(109) Mecyclothorax bicoloratus sp. n.

Diagnosis.

This species (Fig. 143D) shares the bicolored elytra, punctate discal elytral striae, and setal formula 2 1 2 0 with its cryptic sibling species, Mecyclothorax bicoloris (Fig. 143C). As detailed under that species’ treatment, the more intensely microsculptured vertex can externally diagnose individuals of this species, with the isodiametric sculpticells upraised, their individual reflections producing a textured look to the surface. Also, the elytral lateral marginal depression is broader laterad the humerus in this species (Fig. 143D). The aedeagus of this species has a broadly rounded median lobe apex (Fig. 144 H–I) instead of the ventrally pointed apex of Mecyclothorax bicoloris males (Fig. 144 D–G). Standardized body length 4.1-4.8 mm.

Description

(n = 5). [The above description of Mecyclothorax bicoloris can serve to describe this species. All diagnostic characters are presented above, so only the various recorded ratios are presented below.] Eyes moderately convex, covering much of the protruded ocular lobes, ocular ratio = 1.44-1.50, ocular lobe ratio = 0.79-0.84. Pronotum transverse, MPW/PL = 1.18-1.30, lateral margins distinctly sinuate for short distance anterad right to slightly acute hind angles, MPW/BPW = 1.54-1.64. Elytra narrowly subquadrate, MEW/HuW = 2.05-2.14.

Male genitalia (n = 2). Aedeagal median lobe gracile, distance from parameral articulation to tip 3.7 × depth at midlength (Fig. 144 H–I); apex parallel sided, of variable breadth, extended 1.5 –2.7× minimum depth beyond ostial opening, tip with apical face less convex dorsad rounded juncture with ventral margin; internal sac with evident, broadly diffuse dorsal ostial microtrichial patch (uneverted specimen, Fig. 144H); flagellar plate of moderate size, length 0.35 × parameral articulation-tip distance (uneverted specimens, Fig. 144 H–I). Both figured specimens were collected at State Fence Camp on Helele‘ike‘oha Stream, and as there are no other features that diagnose these males, variation in the breadth of the median lobe and its apex is considered infraspecific.

Female reproductive tract (n = 1). Bursa copulatrix broad basally, with parallel-sided apical lobe with rounded apex, overall length 0.76 mm, apical lobe 0.60 mm long × 0.29 mm broad, base at vagina 0.38 mm broad (Fig. 145C); bursal walls translucent, thickly wrinkled; gonocoxite 1 with 3-4 apical fringe setae, the medial 1 or 2 smaller (Fig. 146C), a curved seta at apicomedial angle and 9-10 setae on medial surface; gonocoxite 2 narrowly subtriangular, with apex curved laterad, lateral margin straight near ensiform setae and base moderately extended laterally, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.76-0.79 gonocoxite length.

Holotype.

Female (CUIC) labeled: HI:Maui Haleakala N.P. / Kipahulu Vy. 1800m el. / 8-V-1991 sifting / leaf litter by day // S. Jessel / A.C. Medeiros / Jr. collectors // 2 // HOLOTYPE / Mecyclothorax / bicoloratus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui: Hana For. Res., Heleleikeoha Str. State Fence Camp, pyrethrin fog Metrosideros /moss, 1615 m el., 11-v-1998 lot 06, Polhemus (NMNH, 2), 12-v-1998 lot 03, Liebherr (CUIC, 1), lot 10 Polhemus (CUIC, 1; NMNH, 1).

Etymology.

The adjectival species epithet bicoloratus is used to name the second bicolored species in the Mecyclothorax palustris group, adding to the examples of sibling species named with the same word stem.

Distribution and habitat.

The distribution of Mecyclothorax bicoloratus lies to the east of that of Mecyclothorax bicoloris , with the known localities in upper Kīpahulu Valley (1800 m elevation) or the Helele‘ike‘oha Stream drainage at 1615 m elevation (Fig. 148). All specimens have been collected in association with ‘ōhi‘a, either in leaf litter or via pyrethrin fog application to mossy trunks and logs.