Mecyclothorax crassulus, 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 : 198-199

Taxon classification Animalia Coleoptera Carabidae

(082) Mecyclothorax crassulus sp. n. Figs 96J, 97E, 98E, 100C, 101

Diagnosis.

This adelphotaxon (Fig. 100C) to Mecyclothorax crassuloides (Fig. 100B) can be diagnosed externally by the elytral microsculpture, with the discal intervals covered with a shallow isodiametric mesh, and the lateral intervals with more transverse sculpticells, the microsculpture of all intervals visible in areas of reflected microscope light. The elytral apex bears a distinctly isodiametric mesh, with the sculpticell centers upraised, as opposed to the flat tiling of the isodiametric sculpticells on the elytral apex of Mecyclothorax crassuloides . As for this species’ sister taxon, the male aedeagal median lobe provides a certain diagnosis, with the lobe of Mecyclothorax crassulus more gracile throughout its length, and the apex narrower (Fig. 96J). The internal sac differs also, beings smaller and bearing less melanized spicules. Setal formula 2 1 2 0. Standardized body length 4.6-4.9 mm.

Description

(n = 5). As the microsculptural characters above are the only reliable external anatomical characters yet found to diagnoses these two species, the description of Mecyclothorax crassuloides can serve for this species as well, allowing the following substitutions involving non-diagnostic mensural and qualitative characters. Head capsule with eyes large, variably convex, ocular ratio = 1.47-1.62, ocular lobe ratio 0.77-0.85; labral anterior margin nearly straight; mentum tooth with sides right, apex rounded. Pronotum moderately transverse, MPW/PL = 1.22-1.31, distinctly constricted basally, MPW/BPW = 1.67-1.79; hind angle slightly obtuse, lateral margin subparallel for 0.12 × pronotal length; median base depressed relative to disc, with ~16 small isolated punctures each side; basal margin slightly convex between hind angles, not extended posteriorly near angles; pronotal apical width nondiagnostically narrower relative to basal width in this species versus Mecyclothorax crassulus , APW/BPW = 1.08-1.17. Elytra tending to be narrower (Fig. 100C), more subellipsoid than in Mecyclothorax crassulus (Fig. 100B), MEW/HuW = 2.17-2.39; discal striae 2-4 often more evident, traceable as interrupted linear series of very small punctures. Coloration of available specimens extremely variable, ranging from sclerotized but not fully melanized individuals (as in Fig. 100C), to darker, more melanic individuals (e.g. Mecyclothorax crassuloides of Fig. 100B). Darker specimens share the smoky brunneous femoral apex on a flavous femoral base observed in specimens of Mecyclothorax crassuloides .

Male genitalia (n = 2). Aedeagal median lobe robust, broadest basally, distance from parameral articulation to tip 2.5 × basal depth (Fig. 96J), apex elongate, sinuously extended 5 × its depth to obliquely expanded tip with blunt dorsal projection, flattened apical face, and acutely rounded tip (median lobe appears much like a more slender version of that seen in Mecyclothorax crassuloides , Fig, 96I); internal sac with distinct field of macrospicules on right surface near base, otherwise covered with fine microspicules; flagellar plate very large, length 0.67 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded apex, length 0.61 mm, breadth 0.30 mm, bursal walls translucent, thickly wrinkled (Fig. 97E); gonocoxite 1 with 2 apical fringe setae, the medial seta smaller, and 7 smaller setae along medial surface (Fig. 98E); gonocoxite 2 subtriangular with subacuminate tip, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.77 × gonocoxite length.

Holotype.

Male (BPBM) labeled: Kula Pipeline / 8-25-27 Maui // O.H. Swezey / Collector // Ferns // 2 // HOLOTYPE / Mecyclothorax / crassulus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui, Haleakala, 1524 m el., 08-iii-1912, Rock (BPBM, 1); Olinda, 1207 m el., 13-vi-1918, Giffard/Fullaway (BPBM, 1); Waikamoi N.C.P., Honomanu drainage transect 3, sift litter, 1700 m el., 10-iv-1991 lot 01, Liebherr (CUIC, 2), sift moss and litter, 1680 m el., 08-v-1991 lot 07, Kavanaugh (CAS, 1).

Etymology.

This adjectival species epithet crassulus lies intermediate along the Mecyclothorax crassus - Mecyclothorax crassuloides linguistic cline. The adjectival crassulus is the diminutive of crassus -thick, heavy-used by Sharp (1903) for Mecyclothorax crassus of West Maui ( Liebherr 2011).

Distribution and habitat.

Mecyclothorax crassulus is a species of the Waikamoi forest area (Fig. 101), with historically collected specimens from Olinda and Kula Pipeline (~1200 m elevation) complemented by more recent collections in the Honomanu drainage at ~1700 m elevation. Associated ecological collection data are limited to beating ferns, and sifting moss and leaf litter.