Mecyclothorax bradycelloides, 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 : 78-79

Taxon classification Animalia Coleoptera Carabidae

(028) Mecyclothorax bradycelloides sp. n. Figs 44B, 45 B–C, 48

Diagnosis.

This species (Fig. 44B), Mecyclothorax anthracinus (Fig. 44E), and Mecyclothorax inconscriptus (Fig. 50A) represent the three smallest-bodied species in this group, with all individuals equal to or less than 4.1 mm length. Of these, Mecyclothorax bradycelloides is the only species without fused elytral striae, though the impressions of the dorsal elytral setae are large, crossing most of the width of interval 3. The pronotum is also the most constricted basally, with MPW/BPW = 1.56 versus a collective span of 1.42-1.53 for the other two species. The elytral margins are straight and nearly parallel at elytral midlength, though the tightly rounded humeral angles are narrowly separated relative to elytral width due to the broadly rounded elytral margins laterad the angles; MEW/HuW = 2.0. Setal formula 2 2 2 2. Standardized body length 4.1 mm.

Description

(n = 1). Head capsule with frontal grooves deep and broad near clypeus, narrowed toward anterior supraorbital seta; dorsal surface of neck slightly convex; ocular ratio = 1.49, ocular lobe ratio = 0.81; antennae filiform, antennomere 3 with sparse pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum cordate, hind angle obtuse, rounded behind; lateral margin sinuate for short distance anterad hind angle; median base covered with punctures and wrinkles isolated by granulate microsculpture; basal margin nearly straight, slightly convex medially; median longitudinal impression shallow, finely incised; anterior transverse impression deeply incised, complete, crossed by longitudinal wrinkles; anterior callosity broadly, slightly convex; front angles projected, tightly rounded, APW/BPW = 1.07; lateral marginal depression narrow, edge upturned to beaded; laterobasal depression broad, irregular, slightly convex medially. Proepisternum with smooth hind marginal groove; prosternal process medially depressed, with lateral marginal bead. Elytra subquadrate, disc slightly convex; parascutellar seta present on left side, absent on right; parascutellar striole shallow with 6 punctures; sutural interval moderately convex, appearing broader than intervals 2-4 due to elevated juncture at suture; sutural and 2nd striae of subequal depth from base to apex; discal striae with small punctures that cause strial irregularities along length, intervals convex; 7th and 8th intervals of similar convexity mesad subapical sinuation; 2 dorsal elytral setae at 0.23 –0.27× and 0.60 –0.63× elytral length; apical and subapical setae present; lateral elytral setae arranged as anterior series of 7 setae, and posterior series of 4-5 setae; elytral marginal depression moderately broad, lined with sculpticells, margin upturned; subapical sinuation very shallow, broad. Mesepisternum with ~9 shallow punctures in 1-2 rows; metepisternal width to length ratio = 0.81; metepisternum/metepimeron suture distinct. Abdomen with nearly smooth ventrites; suture between ventrites 2 and 3 complete; apical male ventrite with 2 marginal 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, deep, median area carinate. Microsculpture of vertex isodiametric sculpticells arranged in transverse rows; pronotal disc with transverse mesh, the microsculpture parallel in part; pronotal median base with granulate isodiametric sculpticells; elytral disc with irregular elongate transverse mesh and parallel lines; elytral apex with upraised transverse mesh; metasternum with indistinct transverse mesh; laterobasal abdominal ventrites with indistinct transverse mesh. Coloration of vertex rufobrunneous; antennomeres 1-3 flavous, 4-11 rufobrunneous; pronotal disc rufobrunneous, margins narrowly paler, rufoflavous; proepipleuron flavous, proepisternum brunneous; elytral disc rufobrunneous, sutural interval concolorous basally, rufoflavous apically, margins narrowly rufoflavous in lateral depression, apex broadly flavous; elytral epipleuron flavous with rufous cast, metepisternum rufobrunneous; abdominal ventrites 1-5 rufobrunneous, 6 basally rufoflavous, flavous in apical half; metafemur flavous; metatibia flavous with brunneous cast.

Male genitalia (n = 1). Aedeagal median lobe robust, distance from parameral articulation to tip 3 × depth at midlength (Fig. 45B); apex narrowly extended twice its depth beyond ostial opening, tip subangulate where flattened apical face and ventral margin meet; median lobe straight in ventral view, the left margin distinctly incurved to meet blunt tip (Fig. 45C); internal sac with well-developed, heavily sclerotized dorsal ostial microtrichial patch (based on position near apex of ostium (Fig. 45B), and separate ventral ostial microtrichial patch (Fig. 45C); flagellar plate well sclerotized, visible just inside dorsal margin of lobe (Fig. 45B).

Holotype.

Male (NMNH) dissected and labeled: HI:Maui Haleakala / Waikamoi N.C.P. Ukulele / Pipeline 7-V-1998 lot07 / 1465-1495m el. / pyrethrum fog mossy ohia / log D.A. Polhemus // HOLOTYPE / Mecyclothorax / bradycelloides / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Etymology.

The adjectival epithet bradycelloides is based on Moloka‘i’s Mecyclothorax bradycellinus Sharp, with the -oides suffix signifying the similarity between the two species.

Distribution and habitat.

The type locality for Mecyclothorax bradycelloides lies at ~1500 m elevation near Ukulele Camp (Site) of the USGS (1983) Kilohana, Hawaii quadrangle (Fig. 48). This species was found in a pyrethrin fog sample of a mossy ‘ōhi‘a log.