Mecyclothorax arthuri, 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 : 85-88

Taxon classification Animalia Coleoptera Carabidae

(031) Mecyclothorax arthuri sp. n. Figs 45 H–J, 46C, 47C, 49 A–B, 51

Diagnosis.

This species can be diagnosed by the narrow pronotum relative to the elytra, MEW/MPW = 1.64-1.67, and the irregularly anastomosing striae 2-7, resulting in massive convex warts that may or may not be bilaterally symmetrical (Fig. 49 A–B). These characters set this species apart from all others from Haleakalā except Mecyclothorax medeirosi below. That species differs by a relatively broader pronotum (Fig. 49C); MEW/MPW = 1.47. A third species, Mecyclothorax oppenheimeri Liebherr from West Maui, shares the warty elytral condition of Mecyclothorax arthuri and Mecyclothorax medeirosi while exhibiting a pronotum of relative width intermediate to that of those two species; i.e. MEW/MPW = 1.52-1.57 ( Liebherr 2011, fig. 36). Setal formula: 2 1 2 0(1-2)[sae]. The variation in the apical elytral setae is distributed as: 5 individuals with both setae absent; 1 individual with apical seta absent and subapical setae present; and 1 individual with both apical and subapical setae present. Standardized body length 4.0-4.4 mm.

Description

(n = 5). Head capsule with frontal grooves deep near clypeus, straight, with external carina; dorsal surface of neck flat to convex; eyes moderately convex, ocular ratio = 1.43-1.47, covering ¾ of slightly protruded ocular lobe, ocular lobe ratio = 0.72-0.80; labral anterior margin broadly, moderately deeply emarginate; antennae filiform, antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex rounded. Pronotum bisetose, lateral seta present, basal seta absent, basally constricted, MPW/BPW = 1.46-1.53; hind angle acute, apex acuminate, lateral margin broadly convergent anterad angle; median base depressed relative to disc, with sparsely distributed punctures near basal margin, longitudinal wrinkles at juncture with disc; basal margin straight between laterobasal depressions; median longitudinal impression shallow, indistinct, to deep, distinct, always crossed by transverse wrinkles emanating onto disc; anterior transverse impression deeply incised, complete, short wrinkles extended from impression posteriorly onto disc; anterior callosity broadly convex, smooth; front angles slightly produced, tightly rounded; width between front angles greater than basal width, APW/BPW = 1.01-1.08; lateral marginal depression narrow, edge beaded; laterobasal depression broad, a depressed expansion of lateral depression. Proepisternum with 6 minute punctures along hind marginal groove; prosternal process medially depressed, with broad marginal bead. Elytra broadly subquadrate, lateral margins convex from humerus to subapical sinuation; basal groove incrementally recurved, bordering 4 basal convexities mesad tightly rounded to subangulate humeral angle; humeri narrow relative to broadest portion of elytra behind midlength; MEW/HuW = 2.07-2.16; parascutellar seta present; parascutellar striole narrow, deep, directly connected to isolated basal portion of sutural stria; sutural interval as convex as interval 2, though less convex than warty protuberances associated with intervals 3-7; discal striae lined with sculpticells, smooth; sutural and 2nd striae of subequal depth in apical half of elytra; discal striae 2-6 joined irregularly at positions of dorsal elytral setae, larger convexities associated with striae 2-4, smaller more irregular convexities laterad; warty convexities vary among individuals, as well as bilaterally (Fig. 49 A–B); 7th and 8th interval of similar convexity mesad subapical sinuation; 2 dorsal elytral setae at 0.31 × and 0.69 × elytral length, setal impressions very small, shallow, not distinctly associated with a depressed stria; lateral elytral setae arranged in anterior series of 5 setae, an isolated intermediate seta, and 4 posterior setae; elytral marginal depression broad laterally, narrow behind; subapical sinuation shallow, broad. Mesepisternum with 8 shallow punctures in 2 rows; metepisternal width to length ratio = 0.72; metepisternum/metepimeron suture distinct; metathoracic flight wing an ovoid flap 3.3 × long as broad, remnant R and M veins present, flap extended to hind margin of metanotum. Abdomen with indistinct lateral wrinkles on ventrites 1-3; suture between ventrites 2 and 3 complete; apical male ventrite with 2 marginal setae, apical female ventrite with 4 equally spaced marginal setae and median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio 0.20; metatarsomere 4 length along outer lobe 1.2 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, shallow. Microsculpture of vertex a granulate isodiametric mesh; pronotal disc with shallow transverse mesh median base with isodiametric sculpticells and glossy portions; elytral disc and apex with very shallow isodiametric sculpticells in transverse rows; metasternum with distinct transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufobrunneous with piceous cast; antennomere 1 rufoflavous, antennomeres 2-11 rufopiceous; pronotal disc rufobrunneous, pronotal margins broadly paler, rufoflavous; proepipleuron flavous, proepisternum rufous; elytral disc rufobrunneous, sutural interval concolorous basally, rufous apically; elytral marginal depression narrowly rufoflavous, apex concolorous with disc; elytral epipleuron rufoflavous, metepisternum rufous; abdomen rufobrunneous mediobasally, all ventrites flavous laterally, the apical ventrite with apex broadly flavous; metafemur flavous with piceous basal cloud; metatibia rufobrunneous, piceous cast medially.

Male genitalia (n = 1). Aedeagal median lobe slender, distance from parameral articulation to tip 5.1 × depth at midlength (Fig. 45H); apex extended 4 × its depth beyond ostial opening, gradually narrowed to narrowly rounded tip; median lobe constricted laterally toward apex in ventral view, right margin distinctly concave, left margin more gradually narrowed, tip blunt (Fig. 45J); internal sac with bulbous ventral lobe near midlength, apex broadly rounded with small sclerotized flagellar plate visible along dorsal surface of apical lobe (Fig. 45 H–I), sac surface uniformly covered with microspicules.

Female reproductive tract (n = 1). Bursa copulatrix very short, broad, little extended from broad vaginal base, length 0.23 m, breadth 0.40 mm (Fig. 46C); bursal walls translucent, thinly wrinkled; gonocoxite 1 with 3-4 apical fringe setae in oblique series, 4-6 smaller setae on medial surface (Fig. 47C); gonocoxite 2 subtriangular, apex evenly narrowed, base broadly extended laterally, 2 narrow lateral ensiform setae and broad dorsal ensiform seta with rounded apex, apical nematiform setae on medioventral surface at 0.75 × gonocoxite length.

Holotype.

Male (CUIC) dissected and labeled: HI: Maui Haleakala N.P. / Kuiki, below at 2134 m / N20°42.23', W156°08.00', / 16-V-2001 lot 02 sift / litter under ohia lehua / J.K. Liebherr // HOLOTYPE / Mecyclothorax / arthuri / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui: Haleakala N.P., Haleakala Crater, Paliku, 2134 m el., 23-vi-1975, Burkhart (BPBM, 1), Kipahulu Vy., sift litter by day, 2100 m el., 07-v-1991 lot 05, Jessel/Medeiros (CUIC, 3), Kuiki, below, sift Metrosideros litter, 2145 m el., 16-v-2001 lot 02, Liebherr (CUIC, 2).

Etymology.

Patronyms used in this revision honor the contributions of colleagues to the work in hand. The immense contributions of Dr. Arthur Medeiros in teaching the author how to conduct operative science in the Hawaiian rainforest made this entire work possible. Thus this is the first of two patronyms to honor him.

Distribution and habitat.

The known distribution of Mecyclothorax arthuri straddles the head of Kīpahulu Valley, including Paliku in the eastern end of Haleakalā Crater, Kuiki high along the southwest valley rim, and the upper Kīpahulu Camp sampled by Medeiros and Jessel, 2100 m elevation (Fig. 51). Specimens have been collected by sifting leaf litter.