Mecyclothorax rusticus Sharp

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 150-151

Taxon classification Animalia Coleoptera Carabidae

(061) Mecyclothorax rusticus Sharp Figs 74F, 76 I–J, 78D, 80

Mecyclothorax rusticus Sharp 1903: 244; Britton 1948b: 151.

Diagnosis.

Individuals of this species (Fig. 78D) are most like those of Mecyclothorax pusillus (Fig. 78C), and they are best diagnosed by the broader, more convexly margined elytra. The basal groove is recurved evenly on the rounded humeri, not tightly rounded to subangulate as in Mecyclothorax pusillus . Also, the head is narrow relative to the elytra; MEW/MHW = 2.02-2.07, with slightly more elongate antennomeres. The discal elytral striae are deeper and more continuous than in Mecyclothorax pusillus , though the lateral striae are more similar between the species; striae 5-6 discontinuous, stria 7 a series of minute punctures. The pronotal median base is little depressed relative to the disc, and is covered with ~10 isolated, elongate punctures each side, the surface glossy between the punctures. Finally, the vertex is glossy, with only an obsolete transverse mesh visible in angled light, sculpticell breadth 2 –3× length. Setal formula 2 2 2 2. Standardized body length 3.7-4.3 mm.

Identification

(n = 5). The eyes are less convex than in individuals of Mecyclothorax pusillus , but due to the narrower head, the ocular ratio = 1.50-1.53; slightly greater than measured for that species. The pronotum is moderately constricted basally; MPW/BPW = 1.42-1.49. However the base is relatively broad, APW/BPW = 0.91-0.97, versus the subequal apical and basal pronotal widths in Mecyclothorax pusillus . The pronotal disc is glossy, with an obsolete transverse mesh, sculpticell breadth 2 –3× length. The pronotal median base also glossy with shallow isodiametric sculpticells laterally between the punctures. The elytral disc bears shallow isodiametric and transverse sculpticells, breadth 2 × length, in transverse rows, whereas the elytral apex is covered with shallow isodiametric sculpticells in transverse rows.

Male genitalia (n = 1). Aedeagal median lobe slender, distance between parameral articulation and tip 5.2 × depth at midlength (Fig. 76I); apex nearly as broad as median shaft until it curves ventrally to narrow, blunt tip; median lobe sinuously curved apically in ventral view, right margin distinctly and briefly concave, left margin with incurved hitch near bluntly rounded tip (Fig. 76J); internal sac without ornamentation, flagellar plate short (visible in ventral view, Fig. 76J), length 0.29 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar, length 0.46 mm, breadth 0.22 mm basally at vagina, 0.11 mm near rounded apex (a slightly broader version of Mecyclothorax pusillus bursa, Fig. 62L); bursal wall translucent with thin wrinkles; gonocoxite 1 with 2 short apical fringe setae and 4-6 shorter setae on medial surface (Fig. 74F); gonocoxite 2 falcate with broadly rounded apex (worn?), 2 short, broad lateral ensiform setae (also worn?), apical nematiform setae on medial surface at 0.73 × gonocoxite length.

Lectotype.

Male (BMNH) hereby designated, labeled: Mecyclothorax rusticus Type D.S. Haleakala Perkins 254 // Type // Hawaiian Is. Perkins 1904-336. // Haleakala Maui 9½– 10000 ft. Perkins IV-1894 // LECTOTYPE Mecyclothorax rusticus Sharp J.K. Liebherr 1998 (black-margined red label).

Distribution and habitat.

Mecyclothorax rusticus has been collected only by R.C.L. Perkins, with localities ranging 2895-3050 m elevation along his trips to the summit, and also at Holua, 2100-2200 m elevation at the western margin of Haleakalā Crater (Fig. 80).