Mecyclothorax mauiae, 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 : 131-134

Taxon classification Animalia Coleoptera Carabidae

(051) Mecyclothorax mauiae sp. n. Figs 62 D–E, 63D, 68A, 69, 71

Diagnosis.

Among the assemblage of Mecyclothorax ovipennis group species with punctate discal elytral striae and concolorous elytral intervals, this and the next species, Mecyclothorax subternus , stand out due to their broadly ellipsoid to obovoid elytra (Fig. 68 A–B). The pronotum characterizing these species is also very constricted basally-MPW/BPW = 1.58-1.72 for this species-with a minutely punctate, glossy median base. Mecyclothorax mauiae can be diagnosed from Mecyclothorax subternus by the better developed microsculpture: 1, vertex with evident transverse mesh, sculpticell breadth 2 × length; and 2, pronotal and elytral discs and elytral apex with transverse mesh, sculpticell breadth 2 –3× length. The eyes also tend to be less convex and slightly smaller than in Mecyclothorax subternus , with ocular ratio = 1.43-1.50, and ocular lobe ratio = 0.75-0.79 in this species. The final arbiter for any identification involving a male specimen is the apex of the aedeagal median lobe, with the apex always rounded in male of this species (Fig. 69) versus acuminate in Mecyclothorax subternus (Fig. 70 A–D). The degree of strial development varies among individuals of this species, potentially allowing specimens of this species to be confused with those of Mecyclothorax nanunctus of the Mecyclothorax palustris group. That group is characterized by a less depressed apex on elytral stria 2; a character exhibiting some infraspecific variation. Specimens of Mecyclothorax mauiae always exhibit broader pronotal lateral marginal depressions, and more ellipsoid elytra than observed in individuals of Mecyclothorax nanunctus . As with Mecyclothorax subternus , examination of male genitalia will finalize the diagnosis, as the male aedeagal median lobe of Mecyclothorax nanunctus is much more elongate and gracile, with the apex terminated in narrowly projected tip (Fig. 153 D–J). Setal formula 2 1 2 0. Standardized body length 3.4-4.5 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; labral anterior margin very shallowly emarginate medially; antennae filiform, antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex rounded. Pronotum cordate, moderately transverse, MPW/PL = 1.23-1.27; hind angle right to slightly acute, lateral margin convergent just before angle; median base almost coplanar to slightly depressed relative to disc, ~12 sparsely distributed punctures each side; basal margin convexly expanded between laterobasal depressions; median longitudinal impression shallow, finely incised, crossed by fine transverse wrinkles; anterior transverse impression narrow, shallowly incised laterally, obsolete medially; anterior callosity slightly convex, smooth to slightly irregular due to fine wrinkles, surface glossy; front angles slightly projected, rounded; pronotal apical width greater than basal width, APW/BPW = 1.03-1.11; lateral marginal depression moderately narrow, edge beaded anterad lateral seta, broader at front angle, edge little upturned in basal half; laterobasal depression narrow and deep, continuous with lateral depression. Proepisternum with 5 minute punctures along hind marginal groove; prosternal process with narrow median impression, lateral margins broadly beaded between coxae. Elytra broadly obovoid, disc narrowly flat medially, sides steeply sloped; basal grooves briefly recurved to proximate humeral angles, the tightly rounded to subangulate angles defined by hitch at the base of the lateral marginal depression, MEW/HuW = 2.28-2.51; parascutellar seta present; parascutellar striole with 4 isolated punctures, striole may be discontinuous between adjacent punctures; sutural interval slightly more convex than lateral intervals, sutural juncture upraised; sutural stria shallow between deep, round punctures basally, smooth, moderately deep apically, 2nd stria shallower but also with rounded punctures on disc, shallower and broader apically, the two striae of subequal depth at elytral apex; discal striae 3-4 very shallow, punctate on disc, stria 5 very shallow, traceable, striae 6-7 obsolete, associated inner intervals slightly convex, lateral intervals flat; 8th interval convex, though striae are obsolete in that area of elytra; 2 dorsal elytral setae at 0.31 × and 0.56 –0.58× elytral length, setal impressions shallow, spanning ½ to 2/3 width of interval 3; apical and subapical setae absent; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression slightly broader at humerus, narrowed laterally and posteriorly to beadlike at subapical sinuation; subapical sinuation shallow, concavity symmetrical. Mesepisternum with ~8 punctures in 1-2 rows; metepisternal width to length ratio = 0.70; metepisternum/metepimeron suture distinct. Abdomen with irregular lateral wrinkles on ventrites 1-5, lateral depressions on ventrites 3-6; suture between ventrites 2 and 3 complete; apical male ventrite with 2 marginal setae; apical female ventrite with 4 equally spaced marginal setae and median trapezoid of 4, subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.18; metatarsomere 4 length along outer lobe 1.4 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, shallow, median area broad. Microsculpture of pronotal median base obsolete medially, the surface glossy, a transverse mesh present laterally between punctures; metasternum with shallow transverse mesh; laterobasal abdominal ventrites with swirl ing isodiametric and transverse microsculpture. Coloration of vertex rufobrunneous; antennomere 1 flavous, antennomeres 2-3 brunneous, 4-11 with piceous cast; pronotal disc rufobrunneous, lateral margins narrowly, and base and apex rufous; proepipleuron rufoflavous, proepisternum rufobrunneous; elytral disc rufobrunneous basally, apical half the same with piceous cast, sutural interval rufous throughout, intervals 8-9 rufoflavous, paler apically; elytral epipleuron dorsally rufoflavous, ventrally darker, metepisternum rufobrunneous; abdomen with ventrites 1-3 rufobrunneous, ventrites 4-5 darker, rufopiceous, apical ventrite 6 rufoflavous mediobasally, apical half flavous; metafemur flavous; metatibia flavous with brunneous cast.

Male genitalia (n = 50). Aedeagal median lobe variably robust, distance between parameral articulation and tip 2.2 –3.3× depth at midlength (Fig. 69E, M), but apex always little extended beyond ostial opening, with tip broadly rounded (Fig. 69); median lobe symmetrical in ventral view, broadest at midlength of lobe shaft, evenly narrowed to blunt tip which lies on right side of apex (Fig. 69B); internal sac broad, of variable length (Fig. 69 H–J), sac length from ostium to base of flagellar plate 0.77 –1.1× parameral articulation-tip distance, surface unornamented except denser microspicules may occur on ventral surface (Fig. 69J); flagellar plate very large, length 0.60 –0.67× parameral articulation-tip distance.

Female reproductive tract (n = 2). Bursa copulatrix columnar, elongate, length 1.08-1.16 mm, breadth 0.33-0.36 mm, an apical lobe offset from basal portion by curved constriction, apical lobe 0.49 mm long (Fig. 62 D–E); bursal walls translucent with thick wrinkles; gonocoxite 1 with 3-4 apical fringe setae, the outermost setae of series smallest, and 5-8 smaller setae on medial surface (Fig. 63D); gonocoxite 2 falcate with tightly rounded tip, base with lateral panhandle extension with 90° bend at terminus, 2 lateral ensiform setae with apical seta longer and broader, apical nematiform setae on medial surface at 0.68 × gonocoxite length.

Holotype.

Male (CUIC) labeled: HI: Maui Haleakala NW / slope Waikamoi Flume / Waikamoi to Haipuaena / Gulches 11-IV-1991 / el. 1300 m J. Liebherr // under boards in / wet ohia rain / forest // HOLOTYPE / Mecyclothorax / mauiae / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

817 specimens (see Appendix).

Etymology.

This species’ similarity to Mecyclothorax molokaiae of Moloka‘i, suggests use of mauiae as the species epithet, the first declension genitive singular form to mean Maui’s Mecyclothorax .

Distribution and habitat.

Mecyclothorax mauiae is broadly distributed across the windward face of Haleakalā, including Kīpahulu Valley, Kaumakani Peak and the Manawainui Planeze (Fig. 71). Collection localities range 880-1830 m elevation. This species is found in association with a variety of plant substrates, with ‘ōhi‘a and Cibotium ( hāpu‘u) tree ferns most commonly associated with collections. Beetles have also been collected infrequently on koa trunks, and very commonly in sift samples of ‘ōhi‘a litter. Whereas the predominantly ground-dwelling species of the Mecyclothorax robustus and Mecyclothorax sobrinus species groups were trapped extensively in yellow-pan traps in the Waikamoi area (see above), only six specimens of Mecyclothorax mauiae were so trapped at one wet forest site (Kula Pipeline Road, 1183-1280 m elevation, vi-viii-2006, L. LeBlanc, UHIM).