Mecyclothorax major, 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 : 173-174

Taxon classification Animalia Coleoptera Carabidae

(070) Mecyclothorax major sp. n. Figs 90A, 91 A–B, 94

Diagnosis.

With standardized body length 4.5 mm, this is the largest-bodied species of the Mecyclothorax microps group residing across all islands. Like Mecyclothorax minor (Fig. 90B) and Mecyclothorax angusticollis (Fig. 90C), the elytra are parallel sided and narrow relative to the pronotum (Fig. 90A); MEW/MPW = 1.42 for this species. The cuticle is more pallid than observed in Mecyclothorax angusticollis , and the pronotum is more constricted basally than in Mecyclothorax minor . Also, the elytra have a single dorsal elytral seta at the anterior position, resulting in the setal formula 2 2 1 0 unique to this species within the species group.

Description

(n = 1). Head capsule with frontal grooves convexly curved from clypeus to mesad anterior supraorbital seta, broad carina laterad convex groove; dorsal impression of neck slightly concave; eyes little convex, ocular lobe very obtusely extended from gena, ocular ratio = 1.31; ocular lobe ratio = 0.73; 10-11 ommatidia across horizontal diameter of eye; labral anterior margin angularly emarginate medially, impressed 1/7 length of labrum; antennomeres 2-3 with sparse pelage of short setae; antennae submoniliform; mentum tooth with sides acute, apex pointed. Pronotum little transverse, MPW/PL = 1.19, base moderately constricted, MPW/BPW = 1.49, with lateral margin straight to sinuate anterad obtuse hind angle; median base depressed relative to disc, covered with minute punctures basally and minute wrinkles at juncture with disc; basal margin slightly convex between laterobasal depressions; median longitudinal impression finely incised, shallow; anterior transverse impression broad, moderately deep laterally, obsolete medially; anterior callosity coplanar with disc medially, crossed by distinct wrinkles; front angles moderately produced, tightly rounded; pronotal apical and basal widths subequal, APW/BPW = 0.99; lateral marginal depression moderately broad with upturned margin before lateral seta, narrow with upraised margin to hind angle; laterobasal depression with irregular surface, continuous with lateral marginal depression. Proepisternum with 5-6 minute punctures along hind margin; prosternal process broadly depressed medially. Elytra subparallel, disc medially depressed, sides markedly depressed to margins; basal groove broadly recurved on rounded humeri, MEW/HuW = 1.84; parascutellar seta absent; parascutellar striole discontinuous, with 4-5 small punctures; sutural interval coplanar with lateral intervals basally, slightly upraised in apical half; sutural interval deeper and more steeply sided than 2nd stria throughout most of length, striae of subequal depth at elytral apex; discal striae 1-4 shallow, punctate, striae 5-6 a series of isolated punctures, stria 7 absent near midlength; discal intervals 2-4 flat; 8th interval laterad 7th stria of same convexity as more mesal intervals; 1 dorsal elytral seta at 0.23 –0.26× elytral length, setal impressions shallow, spanning ½ width of interval 3; apical and subapical setae absent; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 5 setae; elytral marginal depression moderately broad with margin upraised laterad humerus, beadlike from midlength to subapical sinuation; subapical sinuation shallow, more abruptly incurved anteriorly. Mesepisternum smooth; metepisternal width to length ratio = 0.58; metepisternum/metepimeron suture distinct; metathoracic flight wing length 2.33 × breadth, remnant R and M veins present, apex extended 0.75 × wing remnant’s length beyond hind margin of metanotum (all estimated by viewing through elytra). Abdomen with indistinct lateral wrinkles on ventrites 1-5; suture between ventrites 2 and 3 reduced laterally, effaced; apical male ventrite with 2 marginal setae. Legs-metatarsomere 1/metatibial length ratio = 0.20; 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 an obsolete transverse mesh, sculpticell breadth 2 × length; pronotal disc with obsolete transverse mesh, sculpticell breadth 2 –4× length, portions of disc glossy, median base with mixture of isodiametric and transverse sculpticells, breadth 2 × length; elytral disc with shallow isodiametric mesh in transverse rows, apex with same mesh obsolete; metasternum with distinct transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufoflavous; antennomere 1 flavous, 2-7 rufoflavous (outer antennomeres broken off); pronotal disc and margins rufoflavous; proepipleuron flavous, proepisternum rufoflavous; elytral disc and sutural interval rufoflavous, marginal depression narrowly flavous; elytral apex and apices of intervals 7 -9 flavous apicad terminus of interval 4; elytral epipleuron flavous dorsally, rufoflavous ventrally, metepisternum rufoflavous; abdomen rufoflavous, apical half of apical ventrite 6 flavous; metafemur rufoflavous; metatibia rufoflavous with brunneous cast.

Male genitalia (n = 1). Aedeagal median lobe slender, straight at midlength, shaft abruptly curved ventrally at base and apex (Fig. 91A); distance from parameral articulation to tip 5.4 × depth at midlength; apex broadly extended beyond ostial opening, tip blunt with dorsal angle rounded and ventral angle denticulate; median lobe abruptly curved rightward ear apex in ventral view (Fig. 91B), blunt tip appearing concave in this view; internal sac with broad fields of dark microspicules but no apparent macrospicules (assessed in uneverted type specimen); right paramere parallel sided, broad nearly to apex (Fig. 91A).

Holotype.

Male (BPBM) dissected and labeled: Paliku, Haleakala / Crater, Maui 6500' / VI–20-26– 75 // R. Burkhart / Collector // pitfall trap // ACC. NO. 1990.009 / BISHOP Museum // HOLOTYPE / Mecyclothorax / major Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Etymology.

The Latin adjectival epithet major , i.e. larger, is used for this species in order to contrast it with the following Mecyclothorax minor .

Distribution and habitat.

Mecyclothorax major is known only from Paliku at the eastern margin of Haleakalā Crater (Fig. 94). The lone collecting event was in a pitfall trap, with the little developed eyes of this species also pointing to occupation of ground-level microhabitats.