Mecyclothorax rex, 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 : 239-242

Taxon classification Animalia Coleoptera Carabidae

(097) Mecyclothorax rex sp. n. Figs 126A, 127, 128A, 129A, 130

Diagnosis.

These handsome beetles are instantly recognizable by: 1, the very large body size, standardized body length 6.9-7.4 mm; 2, dark, glossy cuticle; and 3, transverse pronotum-MPW/PL = 1.23-1.27-with projected, glabrous hind angles (Fig. 126A). The discal elytral striae are deep and distinctly punctate, the associated intervals moderately convex. The only other Hawaiian Mecyclothorax of similar body size is the very different-looking Mecyclothorax molops (Fig. 95A). Although only possible to test using first-hand experience, the elytral cuticle is so hard and brittle that use of an insect mounting pin to prepare a fully sclerotized specimen will shatter the elytron (much as would happen during such a pinning exercise for a specimen of Clivina Latreille). Setal formula 2 1 2 1[sae].

Description

(n = 4). Head capsule with frontal grooves broad near clypeus, shallow, lateral convexity very low; dorsal surface of neck flat to convex; ocular lobe obtusely projected from gena, ocular ratio = 1.48-1.56, ocular lobe ratio = 0.79-0.84; labral anterior margin broadly, shallowly emarginate; antennae filiform, antennomeres 2-3 glabrous except for apical setae; mentum tooth with sides acute, apex rounded. Pronotum broad, moderately constricted basally, MPW/BPW = 1.20-1.27; hind angle obtuse, margin behind angle convex, lateral margin anterad angle subparallel for short distance before diverging; median base smooth with minute, isolated punctures; basal margin convex between hind angles; median longitudinal impression shallow, finely incised; anterior transverse impression broad, deep, continuous medially, finely incised at front angles; anterior callosity broadly convex, smooth; front angles subangulate, not protruded; pronotal apex much narrower than basal width, APW/BPW = 0.79-0.83; lateral marginal depression narrow, edge beaded at midlength, slightly broader at front angle, broadly explanate at hind angle; laterobasal depression smooth, deep, continuous with lateral depression. Proepisternum and proepimeron with ~6 large punctures along hind marginal grooves; prosternal process broadly depressed on ventral surface, low marginal bead between coxae. Elytra subparallel with broadly convex apical margins, disc convex, sides depressed; basal groove absent from base of parascutellar interval, angled anteriorly at lateral edge of sutural interval and subangulate humerus at base of stria 6; elytral base broad, MEW/HuW = 1.63-1.70; parascutellar seta present; parascutellar striole shallow, 3-4 isolated punctures along length; sutural interval more convex than lateral intervals, sutural juncture upraised; sutural and 2nd striae of subequal depth on disc, stria 2 evanescent at apex whereas sutural stria finely incised, deep, and smooth; all striae except sutural and 8th absent from elytral apex, elytral surface evenly convex between those striae; 2 dorsal elytral setae at 0.25 × and 0.55 × elytral length, setal impressions small, spanning about 1/3 of interval 3; apical absent, subapical setae present in melanized track of reduced stria 7; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression narrow, lateral margin upturned; subapical sinuation very shallow, internal plica visible from dorsal viewpoint. Mesepisternum with ~20 punctures in 2-3 rows; metepisternal width to length ratio 0.83; metepisternum/metepimeron suture distinct; metathoracic flight wing an elongate strap, 3.7 × long as broad, remnant R and M veins present, the strap extended beyond posterior margin of metanotum for 0.4 × its length. Abdomen with anterior margin of abdominal ventrite 2 depressed along suture; abdominal ventrites 1-6 smooth; suture between ventrites 2 and 3 very shallow but traceable; apical male ventrite with 2 marginal setae and apical female ventrite with 4 equally spaced setae and median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.17; metatarsomere 4 length along outer lobe 1.2 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, shallow. Microsculpture of vertex, pronotal disc and base obsolete, surfaces glossy; elytral disc with obsolete, elongate transverse mesh, apex without microsculpture, surface glossy; metasternum and laterobasal abdominal ventrites with glossy surfaces. Coloration of vertex rufopiceous; antennomere 1 rufoflavous, antennomeres 2-11 with piceous cast; pronotal disc and margins rufopiceous; proepipleuron rufobrunneous with piceous upper margin, proepisternum rufobrunneous with piceous cast; elytral disc rufopiceous, sutural interval concolorous basally to rufobrunneous apically, margins concolorous with disc; elytral epipleuron and metepisternum rufous; abdomen rufous with a piceous cast, apex of apical ventrite only slightly paler; metafemur rufoflavous with median piceous cloud; metatibia rufopiceous with tibial setae golden.

Male genitalia (n = 2). Aedeagal median lobe large, moderately gracile, distance from parameral articulation to tip 3.9 × depth at midlength (Fig. 127A); apex extended 2.5 × depth beyond apex of ostial opening, curved dorsally near tip that is slightly expanded dorsally, and broadly convex apically; median lobe straight in ventral view, lateral margins evenly convergent to knifelike apex that is slightly curved toward left at tip (Fig. 127B); internal sac narrow, stalklike, with a broad dorsal ostial microtrichial patch at base, and ventral surface broadly covered with shaggy, melanic, microspicules (Fig. 127C); flagellar plate elongate, as long as membranous internal sac, and 0.64 × as long as parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded apex and basal constriction, length 1.48 mm, breadth 0.74 mm, basal constriction 0.45 mm broad (Fig. 128A); bursal walls translucent, thickly wrinkled; gonocoxite 1 with 3 apical fringe setae, the middle seta of series largest, a curved seta at medioapical angle and 8-10 setae on medial surface (Fig. 129A); gonocoxite 2 narrowly subtriangular with tightly rounded apex, base only moderately extended laterally, 2 lateral ensiform setae with apical seta broader and longer than basal seta, apical nematiform setae on medioventral surface at 0.70 × gonocoxite length.

Holotype.

Female (CUIC), right elytron cracked at pin, labeled: HI: Maui Haleakala NW / slope Waikamoi Flume / Waikamoi to Haipuaena / Gulches 11-IV-1991 / el 1300 m J. Liebherr // 3 // HOLOTYPE / Mecyclothorax / rex / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui: Koolau For. Res., Flume Rd., wet forest, yellow pan trap, 1280 m el., vi-viii-2006, Leblanc (UHIM, 1), Kula Pipeline Rd., wet forest, yellow pan trap, 1183-1280 m el., vi-viii-2006, Leblanc (CUIC, 5; UHIM, 6), Waikamoi Gulch, 1210 m el., vii-1956, Namba (BPBM, 1), Waikamoi Flume, beat scrape Metrosideros , 1310 m el., 26-v-1997 lot 06, Liebherr (CUIC, 1), Waikamoi-Maile Tr., ecotone forest, yellow pan trap, 1426-1573 m el., vi-viii-2006, Leblanc (UHIM, 1); Waikamoi N.C.P., Keanae Gap, Camp 6, 1524 m el., 09-i-1998 lot 01, Haines (CUIC, 1).

Etymology.

At 7.4 mm, the largest individuals of this species are among the largest Mecyclothorax beetles in Hawai‘i, and so the species epithet rex -Latin for king-seems an appropriate epithet to apply.

Distribution and habitat.

Mecyclothorax rex is a species of wet forest in the Waikamoi area, with an easternmost limital record in Ke‘anae Valley (Fig. 130). Localities range 1210-1573 m elevation. Most specimens have been collected from ground level, either under boards or in yellow-pan traps within ‘Ōhi‘a Wet Forest. One specimen was found in scraped moss from the trunk of a larger ‘ōhi‘a tree.