Mecyclothorax angusticollis (Blackburn)

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 176-177

Taxon classification Animalia Coleoptera Carabidae

(072) Mecyclothorax angusticollis (Blackburn) Figs 90C, 91 D–E, 92A, 93A, 94

Cyclothorax angusticollis Blackburn 1878b: 156; Blackburn and Sharp 1885: 216.

Mecyclothorax angusticollis , Sharp 1903: 246; Britton 1948b: 155.

Diagnosis.

This species is distinguished from all others in the group by the transverse pronotum (Fig. 90C), MPW/PL = 1.21-1.28, that is broad relative to the elytra, MEW/MPW = 1.35-1.39. Most similar to Mecyclothorax minor , Mecyclothorax angusticollis can also be distinguished from that species by the distinct isodiametric sculpticells in transverse rows on the elytral disc and apex. Body coloration is darker as well, with the pronotal disc rufobrunneous to rufopiceous, and the elytra rufobrunneous, in some instances with an apical rufopiceous cloud. Setal formula 2 2 2 0. Standardized body length 3.2-3.7 mm.

Identification

(n = 5). The eyes are relatively flat, ocular ratio = 1.32-1.39, and cover about ¾ of the ocular lobe, ocular lobe ratio = 0.75-0.79. The labrum is medially emarginate 1/5-1/6 of its length. The pronotal hind angles are obtuse rounded and little projected, the lateral margin only briefly subparallel before the angle. The pronotal median base is slightly depressed relative to the disc, but well set off by the dense elongate punctures and wrinkles, and the upraised isodiametric and transverse sculpticells over the surface. The elytral striae are well developed, with striae 1-6 and 8 complete and moderately deep on disc, stria 7 shallower. Striae 1-6 are distinctly punctate in basal ¾ of length. Sutural stria deep to apex, stria 2 shallower in apical half, except for deep portion parallel to deepened apex of stria 7. The 8th interval is broadly convex, slightly more so than inner intervals. The lateral elytral setae are arranged in an anterior series of 6 setae and a posterior series of 4 setae.

Male genitalia (n = 2). Aedeagal median lobe gracile, distance from parameral articulation to tip 3.9 × depth at midlength (Fig. 91D); apex extended for twice breadth beyond ostial opening, dorsal surface broadly expanded before evenly rounded tip; median lobe curved rightward near apex in ventral view, right and left margins parallel before bluntly rounded apex that is offset to the right (Fig. 91E); internal sac with small, well-sclerotized ventral ostial microtrichial patch (on left of sac, Fig. 91E); flagellar plate of moderate size, length 0.40 × parameral articulation-tip distance (estimated by viewing ovoid sclerotized plate in ventral view, Fig. 91E).

Female reproductive tract (n = 1). Bursa copulatrix columnar with apical cap separated by constriction, overall length 0.67 mm, apical cap breadth 0.23 mm, medial shaft breadth 0.30 mm (Fig. 92A); bursal walls translucent with thin wrinkles; gonocoxite 1 with 3 small apical fringe setae and 6 very small setae on medial surface (Fig. 93A); gonocoxite 2 broadly subtriangular, apex evenly curved laterally, base evenly expanded laterally, 2 lateral ensiform setae, apical nematiform setae on medial surface at 0.67 × gonocoxite length.

Lectotype.

Male (BMNH) hereby designated, labeled: mounting platen with Blackburn Maui code ( Zimmerman 1957: 210), angustic (on reverse) // Type // Hawaiian Is. Rev. T. Blackburn 1888-30. // Lectotype Cyclothorax angusticollis Blackburn J.K.Liebherr 1998 (black-margined red label).

Distribution and habitat.

Mecyclothorax angusticollis was collected repeatedly by Blackburn and Perkins in the late 19th Century (Perkins lots 112, 115, 120, 251, 350, 366, 367, 369, 371, 372, 597, 604, 605, 615, 680; Anonymous N D). Yet the only 20th Century record was a single specimen collected by beating vegetation at 1830-1980 m elevation (E.C. Zimmerman, BPBM). This species appears to have been a species of the forest edge (Fig. 94), with the historical collecting sites now extensively disturbed, the old forest edge gone.