Mecyclothorax nubicola (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 : 146-147

Taxon classification Animalia Coleoptera Carabidae

(058) Mecyclothorax nubicola (Blackburn) Figs 78A, 79

Cyclothorax nubicola Blackburn 1878b: 156.

Mecyclothorax nubicola , Sharp 1903: 244; Britton 1948b: 150.

Cyclothorax rupicola (lapsus calami), Blackburn and Sharp 1885: 216 ( Sharp 1903: 244).

Diagnosis.

This species is uniquely characterized by the very broad pronotum and the remarkably narrow, subparallel elytra (Fig. 78A); MEW/MPW = 1.31-1.36. The only other Haleakalā species to approach this conformation is Mecyclothorax pusillus (Fig. 78C). The pronotum of Mecyclothorax nubicola also distinctively diagnoses the species, with the hind angles represented by a slight widening of the lateral marginal bead, with the lateral margin only slightly sinuate anterad the very obtuse angle. Also, this species is composed of small beetles; standardized body length 3.4-3.5 mm. The setal formula of 2 2 2 2 is shared with the following three species; Mecyclothorax krushelnyckyi , Mecyclothorax pusillus , and Mecyclothorax rusticus . All four species also lack the parascutellar seta.

Identification

(n = 3). The eyes are moderately convex; ocular ratio = 1.46-1.52, ocular lobe ratio 0.81-0.82. The pronotal disc is smooth, with a fine median longitudinal impression and moderately deep, finely incised anterior transverse impression. The median base contrasts to the disc as it is rugose, and is covered with ~10 densely distributed, elongate punctures each side, with fine longitudinal wrinkles at the base-disc juncture. The elytral basal groove is distinctly recurved laterally, with the humeral angle defined by a hitch at the base of the lateral marginal depression; MEW/HuW = 1.80-1.94. Discal elytral striae 1-3 are continuous, punctate, whereas stria 4 is interrupted along its length, and stria 5 is a series of punctures. Microsculpture is reduced in this species, with the frons and vertex glossy and covered with an obsolete transverse mesh. The pronotal disc has transverse lines in part, the cuticle glossy between these areas of microsculpture, whereas the pronotal median base is glossy medially, with irregular sculpticells laterally. The elytral disc bears very shallow isodiametric sculpticells in transverse rows.

Holotype.

Female (BMNH): mounting platen with Blackburn Maui label ( Zimmerman 1957: 210), Cyc nubicola (on reverse) // Type // Hawaiian Is. Rev. T. Blackburn 1888-30 // HOLOTYPE Cyclothorax nubicola Blackburn J.K. Liebherr 1998 (black-margined red label).

Distribution and habitat.

Mecyclothorax nubicola is a fourth summit-dwelling Mecyclothorax species, but it was not collected by Perkins in 1894 or 1896. The species is known from only four specimens and three localities (Fig. 79); the holotype described by Blackburn (1878b) from 10,000 ft. (3040 m), a Timberlake specimen (UCRC) from "gulch near Puu Nianiau, 6000 ft." (1820 m; most probably the head of Waikamoi Gulch), and two specimens from Leleiwi Overlook, 2650 m elevation (P.D. Krushelnycky, CUIC, UHIM). The latter two specimens were collected in a pitfall trap in subalpine shrubland, though the summit record suggests also historical occupation of the alpine zone by this species.