Mecyclothorax xestos, 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 : 177-179

Taxon classification Animalia Coleoptera Carabidae

(073) Mecyclothorax xestos sp. n. Figs 90D, 94

Diagnosis.

This species (Fig. 90D) plus the following 2 species, Mecyclothorax orbiculus (Fig. 90E), and Mecyclothorax contractus (Fig. 90F), comprise the only species of the Mecyclothorax microps group that can be characterized by presence of both supraorbital setae and both pronotal setae, but much reduced elytral setation; no dorsal elytral setae or subapical and apical setae present; base setal formula 2 2 0 0. As the single known specimen of this species unilaterally lacks the anterior supraorbital seta on the right side, this species’ setal formula is scored 2(1) 2 0 0. As in all Mecyclothorax microps group species, the parascutellar seta is also absent. This setal configuration relegates the lateral elytral setae to be the sole setiform sensory organs of the dorsal hindbody. Mecyclothorax xestos exhibits the most reduced elytral striation of the three species, with: 1, only the sutural and 2nd striae shallow, evident; 2, striae 3-4 traceable only as irregular, shallow grooves; 3, striae 5-6 very shallow, obsolete and interrupted; and 4, stria 7 absent basally, traceable only near elytral apex. Standardized body length 3.8 mm.

Description

(n = 1). Head capsule with frontal grooves narrow, a broad convexity laterad groove and fine carinae mesad eye; dorsal impression of neck broadly, slightly concave; eyes flat externally and small, ocular ratio = 1.28, ocular lobe ratio = 0.67; 9-10 ommatidia across horizontal diameter of eye; labral anterior margin angularly emarginate medially 1/7 of length; antennae nearly moniliform, antennomeres 2-3 with few very short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum slightly transverse, MPW/PL = 1.20, basally constricted, MPW/BPW = 1.52; hind angle right to slightly acute, lateral margin subparallel to convergent for short distance anterad angle; median base depressed relative to disc, covered with longitudinal strigae; basal margin slightly convex between laterobasal depressions; median longitudinal impression finely incised, shallow but evident; anterior transverse impression broad, shallow, obsolete medially; anterior callosity coplanar with disc medially, slightly raised laterally, smooth, glossy; front angles not projected, tightly rounded; apical and basal pronotal widths subequal, APW/BPW = 0.98; lateral marginal depression narrow, edge upraised throughout length, slightly wider at front angle; laterobasal depression with irregular surface, continuous with lateral depression. Proepisternum with numerous small irregularities along hind marginal groove due to microsculpture; prosternal process broadly depressed medially. Elytra broadly subellipsoid, disc flat medially, moderately sloped at sides and apex; basal groove evenly curved anterad to angulate humeral juncture with lateral marginal depression, MEW/HuW = 1.90; parascutellar seta absent; parascutellar striole very shallow, smooth, hard to trace; sutural interval slightly upraised throughout length; discal intervals 2-4 flat; 8th interval laterad 7th stria more convex than more mesal intervals; elytral marginal depression moderately broad, margin upraised laterad humerus, beadlike from midlength to subapical sinuation; subapical sinuation shallow, more abruptly incurved anteriorly. Mesepisternum with ~9 punctures in 2-3 rows; metepisternal width to length ratio = 0.68; metepisternum/metepimeron suture distinct. Abdomen with indistinct lateral wrinkles on ventrites 1-3, circular depressions on ventrites 3-6; suture between ventrites 2 and 3 reduced laterally, effaced; apical female ventrite with 4 equally spaced marginal setae plus median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.20; metatarsomere 4 length along outer lobe 1.3 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, basal tarsomeres medially subcarinate. Microsculpture of vertex a 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; elytral disc with regular transverse mesh, sculpticell breadth 2 × length on disc, 3 –4× length laterally, apex with transverse mesh, sculpticell breadth 2 –3× length; metasternum with distinct transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufous, clypeus rufoflavous; antennomeres 1-3 flavous, 4-11 rufoflavous; pronotal disc rufous with brunneous cast, lateral margins, base, and apex broadly rufoflavous; proepipleuron flavous, proepisternum rufobrunneous; elytral disc rufobrunneous with reflective sheen, sutural interval rufoflavous basally, flavous api cally; elytral lateral marginal depression and interval 9 rufoflavous, elytral apex and intervals 7-9 flavous apicad terminus of interval 4; elytral epipleuron flavous dorsally, rufoflavous ventrally, metepisternum rufobrunneous; abdominal ventrite 1 rufobrunneous, ventrites 2-3 medially rufopiceous, laterally rufoflavous, ventrites 4-5 and base of 6 rufoflavous, apical half of ventrite 6 flavous; metafemur flavous; metatibia flavous with rufoflavous cast.

Female reproductive tract. The lone female specimen was not dissected.

Holotype.

Female (CUIC) labeled: HI: Maui Haleakala / Hanawi N.A.R. Poouli / Cabin 5-V-1998 lot 01 / 1590m el. pyrethrum fog / mossy ohia J.K. Liebherr // HOLOTYPE / Mecyclothorax / xestos Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Etymology.

This species epithet is the Greek xestos , or scraped, planed, smoothed, or polished ( Brown 1956).

Distribution and habitat.

The type specimen was collected near Kuhiwa Stream at 1590 m elevation in Hanawī (Fig. 94) in a pyrethrin fog samples of several moss-covered ‘ōhi‘a trees. Seven other Mecyclothorax spp. were also collected in this set of samples taken within a radius of 30 m: Mecyclothorax crassuloides , Mecyclothorax kipwilli , Mecyclothorax mauiae , Mecyclothorax pau , Mecyclothorax perstriatus , Mecyclothorax poouli , and Mecyclothorax robustus .