Mecyclothorax vitreus Britton

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 223-224

Taxon classification Animalia Coleoptera Carabidae

(091) Mecyclothorax vitreus Britton Figs 115 A–B, 116 A–C, 117A, 118A, 119

Metrothorax laticollis Sharp 1903: 271 (junior homonym of Mecyclothorax laticollis Sloane 1900: 565).

Mecyclothorax vitreus Britton 1948b: 134.

Diagnosis.

Beetles of this species display the most vivid bluish metallic reflection of any species in the group (Fig. 115 A–B). That characteristic in combination with the more transverse, glabrous pronotum, MPW/PL = 1.18-1.23 assures facile identification even in the field. The elytra vary in shape, with the humeral area broader (Fig. 115A) or narrower (Fig. 115B); MEW/HuW = 2.12-2.30. Setal formula 2 0 2 0. Standardized body length 4.9-5.6 mm.

Identification

(n = 5). The eyes are convex, ocular ratio = 1.46-1.57, and cover much of the protruded ocular lobe, ocular lobe ratio = 0.81-0.87. The pronotal hind angles are right to slightly obtuse, with the margin behind the angles convex, and the lateral margins anterad the angle variably convergent. The pronotal median base is minutely punctured, with ~23 punctures each side isolated by glossy cuticle. The pronotal anterior transverse impression is broad and shallow, and lined with dense longitudinal wrinkles that extend medially across the anterior callosity. The pronotal lateral marginal depression is extremely narrow, constituted only by the beaded margin adjacent to the pronotal disc. The pronotal apex is distinctly broader than the base; APW/BPW = 1.14-1.20. All elytral intervals are flat, though the sutural interval may be slightly convex on the middle of the disc (Fig. 115A), with the sutural stria the most punctate. The 2nd stria may be serially punctate and slightly impressed on the disc, or indicated by a series of isolated punctures. The vertex is glossy, bearing only obsolete microsculpture that is difficult to discern. The pronotal disc and median base are also glossy, with obsolete transverse microsculpture over parts of the discal surface and obsolete isodiametric sculpticells in the laterobasal depression. The elytral disc is glossy with an obsolete, elongate transverse mesh; patches of elongate transverse sculpticells on the elytral apex.

Male genitalia (n = 2). Aedeagal median lobe gracile, distance from parameral articulation to tip 4.1 × depth at midlength (Fig. 116A, C); apex narrowly extended beyond ostial opening 3 × its minimum depth, tip curved ventrally with oblique apical face; median lobe straight in ventral view, though right and left margins are sinuously subparallel as they narrow to an acuminate tip (Fig. 116B); internal sac with evident, though small, dorsal and ventral ostial microtrichial patches (left and right patches in ventral view, Fig. 116B); flagellar plate apparently short based on uneverted specimen (Fig. 116A), length 0.29 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded apex, length 0.94 mm, breadth 0.38 mm (Fig. 117A); bursal walls thickly wrinkled, base more translucent, apex more opaque; gonocoxite 1 with 3-4 apical fringe setae, a curved seta at medioapical angle and 6-7 smaller setae along medial surface (Fig. 118A); gonocoxite 2 narrowly falcate with tightly rounded tip and elongate basal extension with curved terminus, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.72 × gonocoxite length.

Lectotype.

Female (BMNH) hereby designated, labeled: Metrothorax laticollis Type D.S. Hawaii Perkins 680 // Type // Hawaiian Is. Perkins 1904-336. // Mecyclothorax vitreus n.n. for Metrothorax laticollis Sharp E.B. Britton det. 1939 // LECTOTYPE Metrothorax laticollis Sharp J.K. Liebherr 1998 (black-margined red label). The type locality represented by R.C.L.P. lot 680 is HI: Maui, Haleakala, 4000+ ft. ( Anonymous N D), in the Waikamoi area above Olinda.

Distribution and habitat.

Mecyclothorax vitreus is found at moderate elevations in the Waikamoi area, with all records spanning 1170-1830 m elevation (Fig. 119). More recently is has been collected in association with koa trunks, or by beating vegetation at night.