Mecyclothorax contractus, 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 : 181-183

Taxon classification Animalia Coleoptera Carabidae

(075) Mecyclothorax contractus sp. n. Figs 90F, 92B, 93B, 94

Diagnosis.

This third species of the triplet lacking dorsal elytral setae can be diagnosed by the more quadrate pronotum (Fig. 90F); MPW/PL = 1.07-1.13. The pronotum is relatively less constricted basally in association with the quadrate shape; MPW/BPW = 1.42-1.43. The elytra are subquadrate, the lateral margins extended laterally outside the distinctly angulate humeri, and broader relative to the pronotum than in other Mecyclothorax microps group species; MEW/MPW = 1.56-1.59. Setal formula 2 2 0(1) 0; 1 of the 3 specimens has the anterior dorsal elytral seta present. Standardized body length 4.0 mm.

Description

(n = 3). Head capsule with frontal grooves broad at clypeus, sinuous, with broad convexity laterad groove and thin carina mesad supraorbital seta; dorsal impression of neck slightly concave; ocular lobe little projected, eyes small, little convex, vertical dimension greater than length, ocular ratio = 1.29-1.33, ocular lobe ratio = 0.73-0.78, about 10 ommatidia across horizontal diameter of eye; labral anterior margin angularly emarginate medially, impressed 1/6 length; antennomere 2 with sparse setae at apex, antennomere 3 sparsely setose along shaft; mentum tooth with sides acute, apex pointed. Pronotum with lateral margins broadly sinuate anterad slightly obtuse, projected hind angles, margin behind angle convex; median base depressed relative to disc, covered with punctures and longitudinal strigae; basal margin slightly convex between laterobasal depressions; median longitudinal impression finely incised, shallow but evident, continued onto median base; anterior transverse impression broad, shallow, surface slightly irregular; anterior callosity coplanar with disc medially, slightly raised laterally, smooth, glossy; front angles not projected, rounded; apical and basal pronotal widths subequal, APW/BPW = 0.97-1.04; lateral marginal depression broadest inside front angles, narrow with beadlike margins in anterior half, margin upraised basally; laterobasal depression with irregular surface, continuous with lateral depression. Proepisternum with 5-6 minute punctures along hind marginal groove; prosternal process broadly depressed medially. Elytra subquadrate, the disc flat medially, moderately sloped on sides and apex; the humeral angles are proximate relative to elytral width, MEW/HuW = 1.95-2.0; parascutellar striole with 3 punctures, the striole interrupted between punctures; sutural interval slightly more upraised throughout its length than lateral intervals; sutural striae slightly deeper than 2nd stria basally, of similar depth apically; discal striae 1-4 moderately impressed, minutely punctate, intervals 5-6 shallow but evident with elongate irregularities along length, stria 7 obsolete, interrupted; 8th interval laterad 7th stria of same convexity as more mesal intervals; 1 dorsal elytral seta present in 1 of 3 specimens at 0.23 –0.26× elytral length, setal impression shallow, spanning ½ width of interval 3; lateral elytral setae arranged in anterior series of 6(7) setae and posterior series of 5(6) setae; elytral marginal depression moderately broad with upraised margin outside humerus, beadlike from midlength to subapical sinuation; subapical sinuation shallow, more abruptly incurved anteriorly. Mesepisternum with ~7 punctures in 2 rows; metepisternal width to length ratio = 0.88; metepisternum/metepimeron suture distinct; metathoracic flight wing 2.33 × long as broad, with remnant R and M veins, the vestigium extended for 0.75 × its length beyond hind margin of metanotum. Abdomen with indistinct lateral wrinkles on ventrites 1-5; suture between ventrites 2 and 3 reduced laterally, effaced; apical female ventrite with 4 equally space marginal setae plus median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.19; metatarsomere 4 length along outer lobe 1.5 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, basal tarsomeres medially subcarinate. Microsculpture of vertex very shallow isodiametric and transverse mesh, sculpticell breadth 2 × length mesad eyes; pronotal disc with shallow transverse mesh, sculpticell breadth 2 –4× length, median base with mixture of isodiametric and transverse sculpticells, breadth 2 × length, apex with transverse mesh, sculpticell breadth 4 × length; metasternum with distinct transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufous; antennomeres 1-3 flavous, 4-11 rufoflavous; pronotal disc rufous, lateral margins, base, and apex broadly rufoflavous; proepipleuron rufoflavous, proepisternum rufobrunneous; elytral disc rufobrunneous with reflective sheen, sutural interval rufoflavous basally, flavous apically; elytral marginal depression and 9th interval rufoflavous, intervals 7-9 and apex apicad terminus of interval 4 tending toward flavous; elytral epipleuron flavous dorsally, rufoflavous ventrally, metepisternum rufobrunneous; abdominal ventrite 1 and 4-6 rufoflavous, ventrites 2-3 rufobrunneous, apical half of apical ventrite 6 flavous; metafemur flavous; metatibia flavous with rufoflavous cast.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded apex, length 0.67 mm, breadth 0.23 mm (Fig. 92B); bursal walls translucent with thin wrinkles; gonocoxite 1 with 3 small apical fringe setae and 5-6 smaller setae on medial surface (Fig. 93B); gonocoxite 2 narrowly subtriangular, apex rounded, base narrowly extended laterally, 2 lateral ensiform setae with apical seta broader and longer, apical nematiform setae on medial surface at 0.75 × gonocoxite length.

Holotype.

Female (CUIC) labeled: HI: Maui Hanawi N.A.R. / Pig fence helipad sift / humus ex ohia 21-V- / 1993 lot 02 el. 1575 m // 2 // HOLOTYPE / Mecyclothorax / contractus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui, Haleakala, Hanawi N.A.R., Kopiliula Str., pyrethrin fog Cibotium + Metrosideros , 1137 m el., 4-v-1998 lot 02 (CUIC, 1), same data as holotype (CUIC, 1).

Etymology.

The adjectival species epithet contractus means drawn together, or made narrow, and refers to the basally constricted pronotum of beetles in this species.

Distribution and habitat.

This species is known from collecting sites in Hanawī near Kuhiwa and Kopili‘ula Streams, elevations 1137-1585 m (Fig. 94). Two beetles were found in a sift sample of humus associated with a shrublike ‘ōhi‘a tree at the former site, and a third was found in a pyrethrin fog sample of a Cibotium tree fern on a horizontal, mossy ‘ōhi‘a nurse log in the Kopili‘ula drainage.