Mecyclothorax flaviventris, 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 : 136-139

Taxon classification Animalia Coleoptera Carabidae

(053) Mecyclothorax flaviventris sp. n. Figs 62G, 63F, 68 C–D, 70 E–I, 72

Diagnosis.

This species is the most gracile-bodied Mecyclothorax ovipennis group species with cordate pronotum, narrowed elytral humeri, and punctate discal elytral intervals (Fig. 68C). In body conformation it is most similar to Mecyclothorax ovipennis (Fig. 65A), and both species share the setal formula 2 2 2 1[ae]. However individuals of this species lack the parascutellar seta. Also, this species is uniquely characterized among species in the group by the apically flavous abdomen, with the flavous ventrites 4-6 contrasted to the rufobrunneous basal ventrites (Fig. 68D). Standardized body length 3.7-4.1 mm.

Description

(n = 5). Head capsule with frontal grooves broad near clypeus, lateral carina to supraorbital seta; dorsal surface of neck flat to slightly concave; eyes large and moderately convex, ocular ratio = 1.51-1.56, ocular lobe ratio = 0.82-0.88; labral anterior margin deeply angulate medially, emarginated 1/3 of length; antennae filiform; antennomeres 2-3 with only a few short setae along shafts; mentum tooth with sides acute, apex tightly rounded. Pronotum quadrisetose, distinctly constricted basally, MPW/BPW = 1.49-1.58, with lateral margins convergent before the right to slightly acute, projected hind angles; pronotum appearing narrow, but actually slightly transverse, MPW/PL = 1.13-1.21; median base broadly depressed relative to disc, rugose medially, longitudinally strigose laterally; basal margin very slightly convex between laterobasal depressions; median longitudinal impression evident, finely incised, continued onto median base; anterior transverse impression broad, surface with granulate microsculpture and deep, dense longitudinal wrinkles; anterior callosity depressed, covered with longitudinal wrinkles from transverse impression; front angles not projected, tightly rounded; pronotal apical width greater than basal width, APW/BPW = 1.06-1.09; lateral marginal depression moderately narrow, edge upturned, slightly broader inside front angle; laterobasal depression slightly transversely wrinkled, continuous with lateral depression. Proepisternum with 4-5 minute punctures along hind marginal groove; prosternal process with narrow median impression, lateral margins broadly beaded between coxae. Elytra distinctly ovoid with maximal width behind midlength, disc narrowly flat medially, sides steeply sloped; basal groove gently recurved to subangulate humerus that is defined by hitch at base of lateral marginal depression, MEW/HuW = 2.10-2.18; parascutellar striole very shallow, smooth, difficult to trace; sutural interval slightly more convex than lateral intervals, but depressed at suture; sutural and 2nd striae of subequal depth from base to apex, striae 2-6 progressively shallower on disc, stria 7 discontinuous, obsolete, discal striae 1-4 with small punctures restricted to deepest parts of striae; 8th interval slightly more convex than apical fused portion of striae 5 + 7; 2 dorsal elytral setae at 0.30 –0.31× and 0.61 –0.66× elytral length, setal impressions shallow, spanning ½ width of interval 3; apical elytral seta present near medial apex of interval 3, subapical seta absent; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression moderately narrow, edge upraised until beaded at subapical sinuation; subapical sinuation shallow, more abruptly incurved anteriorly. Mesepisternum with ~8 punctures in 1-2 rows; metepisternal width to length ratio = 0.71; metepisternum/metepimeron suture distinct. Abdomen with irregular lateral wrinkles on ventrites 1-5, lateral depressions on ventrites 3-6 (Fig. 68D); suture between ventrites 2 and 3 reduced laterally, effaced; apical male ventrite with 2 marginal setae, apical female ventrite with 4 equally spaced setae plus median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.21; metatarsomere 4 length along outer lobe 1.33 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, shallow, median area broad. Microsculpture of vertex and pronotal disc a transverse mesh, sculpticell breadth 2 –3× length; pronotal median base with granulate isodiametric and transverse mesh, sculpticell breadth 2 × length; elytral disc with shallow isodiametric and transverse mesh, sculpticell breadth 2 × length, in transverse rows; elytral apex with shallow isodiametric sculpticells in transverse rows; metasternum with upraised transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufobrunneous with piceous cast; antennomeres 1-3 flavous, 4-11 darker, more brunneous; pronotal disc rufopiceous, lateral margins, base, and apex narrowly rufoflavous; proepipleuron rufoflavous, proepisternum rufobrunneous; elytral disc dark rufobrunneous, sutural interval narrowly rufobrunneous basally, rufoflavous apically; elytral marginal depression and 9th interval rufoflavous, elytral apex narrowly flavous; elytral epipleuron dorsally flavous, ventrally rufoflavous, metepisternum rufopiceous; abdomen with ventrites 1-2 rufobrunneous, ventrite 3 medially rufobrunneous, laterally and apically flavous, ventrites 3-6 flavous; metafemur flavous; metatibia flavous with a brunneous cast.

Male genitalia (n = 5). Aedeagal median lobe variably gracile, distance between parameral articulation and tip 3.7 –4.2× depth at midlength (Fig. 70E, H, I); apex extended twice its depth beyond apex of ostial opening, tip slightly downturned, rounded; median lobe curved rightward toward apex in ventral view (Fig. 70F), right margin concave, left margin incurved to blunt tip; internal sac elongate, length from ostial margin to base of flagellar plate 0.79 × parameral articulation-tip distance, sac surface unornamented but with microspicules more developed over entire ventral surface (Fig. 70G); flagellar plate moderately short, length 0.36 × parameral articulation-tip distance. The male from Kīpahulu Valley, 1500 m elevation (Fig. 70H) exhibits a broader apex, though the internal sac in its uneverted condition looks identical to the configuration of the Kīpahulu Valley, 1845 m elevation male (Fig. 70E). All of these specimens exhibit the flavous abdominal ventrites that represent an autapomorphy for the species, and if the lower elevation Kīpahulu Valley population is determined to be distinct, the additionally recognized species will be the sister to Mecyclothorax flaviventris . A present, with only a single specimen from the lower Kīpahulu Valley locality, such recognition is deemed premature, and the aedeagal conformations are assumed to represent infraspecific variability.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded, slightly expanded apex, length 0.68 mm, breadth 0.29 mm (Fig. 62G); bursal walls translucent with thin wrinkles; gonocoxite 1 with 0-1 apical fringe setae and 7-8 smaller setae on medial surface (Fig. 63F); gonocoxite 2 falcate with tightly rounded tip, base with long, thin lateral extension with 90° bend at terminus, 2 lateral ensiform setae, the apical seta longer and broader, apical nematiform setae on medial surface at 0.69 × gonocoxite length.

Holotype.

Male (CUIC) dissected and labeled: HI:Maui Haleakala N.P. / Kipahulu Vy. 1500 m el. / 9-V-1991 sifting / leaf litter by day // S. Jessel / A.C. Medeiros, / Jr. collectors // Mecyclothorax / flaviventris / ♂ #4 / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / flaviventris / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

35 specimens (see Appendix).

Etymology.

The Latin genitive singular flaviventris signifies the flavous abdominal ventrites 4-6 contrasted to the piceous abdominal base.

Distribution and habitat.

Mecyclothorax flaviventris has a distribution that is centered on the upper elevations of Kīpahulu Valley, extended northward into the Hāna Bogs, westward to the eastern mesic margin of Haleakalā Crater at Paliku, and southward to Kīpahulu’s west rim near Kuiki (Fig. 72). Collecting localities span 1500-2100 m elevation. The beetles have almost always been collected in association with mossy ‘ōhi‘a trunks and logs. Several beetles have been encountered while beating vegetation, and one was captured in a pitfall trap at Paliku.