Mecyclothorax aquilus, 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 : 249-250

Taxon classification Animalia Coleoptera Carabidae

(100) Mecyclothorax aquilus sp. n. Figs 133A, 134A, 135

Diagnosis.

This is the only Haleakalā species of the group that consistently exhibits a glabrous pronotum (Fig. 133A). Mecyclothorax aquilus is otherwise most similar in appearance to Mecyclothorax insolitus (Fig. 133B) and Mecyclothorax invisitatus (Fig. 133C) sharing the broadly flavous apical elytral margins. However beetles of this species are larger, standardized body length 5.1-5.6 mm, versus a range of 4.2-5.1 mm for the other two species. Setal formula 2 0 2 0.

Description

(n = 2). Head capsule with frontal grooves deep and broad near clypeus, a broad lateral convexity before eye that continues posterad enveloping anterior supraorbital seta; dorsal impression of neck slightly concave; ocular lobe moderately protruded from gena, eyes moderately convex, ocular ratio= 1.48-1.49, ocular lobe ratio = 0.80-0.81; labral anterior margin shallowly emarginate to 1/8 of labral length; antennae filiform, antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum slightly transverse, MPW/PL = 1.11-1.16, the disc broadly convex; hind angles obtuse but sharp apically, lateral margins evenly divergent anterad, MPW/BPW = 1.52-1.56; median base slightly depressed relative to disc, ~20 minute, isolated punctures each side in glossy surface; basal margin distinctly convex between hind angles; median longitudinal impression very finely incised, broader in front of median base; anterior transverse impression very shallow, broad, incised only immediately inside front angle; anterior callosity flat medially, surface glossy; front angles slightly projected, tightly rounded; pronotal apical width variably subequal to basal width, APW/BPW = 0.97-1.06; lateral marginal depression obsolete, narrowly beaded laterally and basally, bead thicker only at hind angle, depression narrow only inside upraised margin of front angle; laterobasal depression deep, sloping from disc, margined by narrow U-shaped depression. Proepisternum with 5 minute punctures along hind marginal groove; prosternal process with broad median depression, lateral margins broadly upraised between coxae. Elytra subovoid, domed, the sides distinctly sloped to a vertical juncture with lateral marginal depression; basal groove evenly and briefly curved to angulate humerus at juncture with broader lateral marginal depression, MEW/HuW = 2.21-2.38; parascutellar striole with 3-5 isolated punctures, the striole shallow between punctures; sutural interval coplanar with lateral intervals basally, upraised in apical half; sutural and striae 2-4 of equal development on disc, but sutural stria the only one complete to base and apex, the basal part shallow and punctate, the apical portion finely incised, smooth and deep; stria 5 traceable only as a series of shallow punctures in basal half, striae 6-7 absent; elytral apex evenly and broadly convex, the lateral surface overlying the deep 8th stria; 2 dorsal elytral setae at 0.33 –0.36× and 0.54 –0.60× elytral length, setal impressions small, spanning ¼ of interval 3; lateral elytral setae arranged in an anterior series of 7 setae and a posterior series of 6 setae; elytral marginal depression narrow throughout, edge upturned at humerus, beaded laterally to subapical sinuation; subapical sinuation shallow, symmetrical. Mesepisternum with ~11 punctures in 2-3 rows; metepisternal width to length ratio = 0.71; metepisternum/metepimeron suture distinct. Abdomen with smooth glossy ventrites, round lateral depressions on ventrites 3-6; suture between ventrites 2 and 3 effaced; apical male ventrite with 2 marginal setae and apical female ventrite with 4 equally spaced marginal setae plus trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.20; metatarsomere 4 length along outer lobe 1.5 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, lateral, upper surface granulate without carina. Microsculpture of vertex an obsolete transverse mesh, sculpticell breadth 2 × length; pronotal disc and base glossy; elytral disc glossy, indistinct transverse lines visible through the reflective sheen; elytral apex glossy, surface irregular but no sculpticells visible; metasternum glossy; laterobasal abdominal ventrites glossy, indistinct sculpticells in lateral depressions. Coloration of vertex rufous with a piceous cast; antennomeres 1-4 rufoflavous, 5-11 slightly darker; pronotal disc rufous with piceous cast, lateral margins narrowly rufous, and base and apex broadly rufous; proepipleuron rufoflavous, proepisternum rufopiceous; elytral disc rufopiceous, sutural interval broadly rufous basally, rufoflavous to flavous apically; elytral margins with intervals 7-8 pale rufous basally, margin more broadly flavous in apical 1/3 where apex of interval 2 is also broadly flavous; elytral epipleuron flavous dorsally, darker ventrally, metepisternum rufopiceous; abdomen with ventrite 1-5 medially rufopiceous, ventrites 3-6 flavous marginally, the apical half of ventrite 6 flavous; metafemur flavous; metatibia flavous with brunneous cast.

Male genitalia (n = 1). Aedeagal median lobe gracile, distance from parameral articulation to tip 4.5 × depth at midlength (Fig. 134A); apex sinuously extended to a dorsoventrally expanded knoblike tip; median lobe curved to right beyond ostial opening in ventral view; internal sac with small dorsal ostial microtrichial patch based on uneverted specimen; flagellar plate short, length 0.32 × parameral articulation-tip distance.

Female reproductive tract. The female allotype was not dissected.

Holotype.

Male (CUIC) dissected and labeled: HI: Maui Haleakala N.P. / Kipahulu Vy. Central / Pali tr. 910 m el. / 30-IV-1991 beating / vegetation at night // J.K. Liebherr / A.C. Medeiros, / Jr. collectors // Mecyclothorax / aquilus / ♂1 / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / aquilus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Allotype.

Female (CUIC) with same data as holotype.

Etymology.

The Latin adjective aquilus -dark-colored, blackish, dun, swarthy ( Brown 1956)-is used to signify the dark body coloration representative of this species.

Distribution and habitat.

Mecyclothorax aquilus is known only from two specimens collected at 915 m elevation in Kīpahulu Valley (Fig. 135). These were collected by sifting moss and leaf litter, and by beating vegetation at night. The 915 m elevation collecting site has large stature koa trees and a high diversity of understory vegetation.