Mecyclothorax subternus, 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 : 135-136

Taxon classification Animalia Coleoptera Carabidae

(052) Mecyclothorax subternus sp. n. Figs 62F, 63E, 68B, 70 A–D, 71

Diagnosis.

Individuals of this species (Fig. 68B) are nearly identical externally to those of Mecyclothorax mauiae (Fig. 68A), though the eyes tend to be larger and more convex; ocular ratio = 1.48-1.54, ocular lobe ratio = 0.79-0.82, and the dorsal surface is less sculptured; 1, vertex, pronotal disc and median base, and elytral disc glossy, microsculpture obsolete; 2, elytral apex with shallow to obsolete transverse mesh, the surface glossy; 3, metasternum with shallow transverse-mesh microsculpture. The male aedeagal median lobe certifies the identification, as the apex terminates in a pointed tip (Fig. 70 A–C) instead of the broadly rounded apex of Mecyclothorax mauiae (Fig. 69). Setal formula 2 1 2 0. Standardized body length 3.4-4.2 mm.

Description

(n = 5). The description of Mecyclothorax mauiae also serves for this species with the following substitutions. Pronotum slightly broader basally and more transverse than that of Mecyclothorax mauiae ; MPW/BPW = 1.57-1.65, MPW/PL = 1.23-1.32. Pronotal lateral margin narrow, beaded, not wider at front angles. Discal elytral striae shallow between deep, rounded and nearly isolated punctures; discal elytral interval 2 slightly convex, intervals 3-4 nearly flat. Mesepisternum smooth, with 3-4 punctures arrayed in 1 row. Coloration pale (though single topotypic type series may include exclusively somewhat teneral individuals); vertex rufous; antennomere 1 flavous, antennomeres 2-3 rufoflavous, 4-11 brunneous; pronotal disc and margins pale rufous; elytral disc basally rufous, apically rufobrunneous, sutural interval basally rufoflavous, apically flavous; abdominal ventrites 1-5 mediobasally rufous, laterally and apically rufobrunneous; metafemur flavous with medial brunneous cloud.

Male genitalia (n = 2). Aedeagal median lobe robust, distance between parameral articulation and tip 2.5 × depth at midlength (Fig. 70 A–C); apex little extended beyond ostial opening, tip acutely pointed; median lobe symmetrical in ventral view, right margin broadly concave, left margin incurved to blunt tip which is on right side of apex (Fig. 70D); internal sac very broad basally, with oblong ventral ostial microtrichial patch on right side (Fig. 70B); flagellar plate very large, length 0.67 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix a broad sac, length 1.23 mm, maximum breadth in apical half 0.65 mm, breadth at vagina 0.34 mm (Fig. 62F); bursal walls translucent with thick wrinkles; gonocoxite 1 with 3 apical fringe setae, middle seta of series largest, 8 smaller setae along medial margin (Fig. 63E); gonocoxite 2 falcate with acuminate tip, base with sinuous lateral extension, 2 lateral ensiform setae with apical seta broader and longer, apical nematiform setae on medial surface at 0.72 × gonocoxite length.

Holotype.

Male (NMNH) labeled: HI:Maui Haleakala Hana- / wi NAR Kuhiwa Vy. E rim / 9-VI-1999 lot 07 880 m el. / N20°46'25", W156°06'04" / D.A. Polhemus pyr. fog / Cibotium // Mecyclothorax / subternus / ♂ #40 / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / subternus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

Same data as holotype (BPBM, 2; CUIC, 3; NMNH, 5).

Etymology.

The adjectival species epithet subternus , meaning that which is underneath ( Jaeger 1955), signifies the geographical range of this species being at the lower elevational bounds of its closely related, and much more broadly distributed relative, Mecyclothorax mauiae (Fig. 71).

Distribution and habitat.

Mecyclothorax subternus is known only from a single locality along the lower elevational limit of the range of its much more extensively distributed cryptic sibling species, Mecyclothorax mauiae (Fig. 71). All 10 specimens of this species came from a single day of collecting on mossy ‘ōhi‘a trunks and logs. The type locality in Kuhiwa Valley is extremely wet both due to precipitation but also due to the extensive rainwater runoff from the upper elevations of Kuhiwa Valley. Yearly rainfall at 871 m elevation in Kuhiwa Valley averaged 9.75 m from 1934-1941 (Stearns and McDonald 1942); the highest average total for any station in East Maui during those years.