Mecyclothorax haydeni, 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 : 72-74

Taxon classification Animalia Coleoptera Carabidae

(026) Mecyclothorax haydeni sp. n. Figs 37E, 38E, 39C, 42, 43

Diagnosis.

Larger bodied beetles within the species group, standardized body length = 5.0-6.2 mm, with broad, subquadrate elytra. The discal elytral striae are lined with small though distinct punctures that at most expand strial breadth, or at least introduce irregularities to the strial orientation (Fig. 38E). The eyes are smaller than those observed in Mecyclothorax robustus individuals (see diagnosis above), though the male genitalic configuration is the only certain means to diagnose the two species. The male median lobe of Mecyclothorax haydeni males exhibits an evenly downcurved apex (Fig. 43), though the degree of narrowing toward the tip and extension beyond the ostial opening varies among individuals (Fig. 43B versus 43D). The male aedeagal internal sac is shorter and narrower in males of Mecyclothorax haydeni (Fig. 43B, F, H) than in males of Mecyclothorax robustus (Fig. 41B, E, G). Setal formula 2 2 2 2.

Description

(n = 5). Head capsule with frontal grooves broad near clypeus, with broad lateral carina to anterior supraorbital seta; dorsal surface of neck flat to slightly concave; labral anterior margin subangulate, medially excavated 0.1 × length; antennae robustly filiform, antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum slightly transverse, MPW/PL = 1.20-1.24, variably constricted basally, MPW/BPW = 1.37-1.50; hind angle slightly obtuse, basal margin rounded posterad angle, lateral margin slightly divergent anterad hind angle; median base depressed relative to disc, covered with dense punctures and wrinkles, surface strigose; basal margin broadly, moderately convex between laterobasal depressions; median longitudinal impression very shallow, finely incised; anterior transverse impression broad, shallow, crossed by wrinkles and lined by granulate isodiametric microsculpture; anterior callosity slightly elevated, crossed by dense longitudinal wrinkles, strigose; front angles slightly projected, rounded; pronotum broader basally than apically, APW/BPW = 0.90-0.95; lateral marginal depression only slightly broader at front angle, moderately narrow, edge upturned; laterobasal depression broad, smooth, with median tubercle. Proepisternum with 6 indistinct punctures along hind marginal groove; prosternal process medially depressed, with broad lateral marginal bead. Elytra subquadrate, disc convex, sides more sloped; basal groove recurved to subangulate humerus, the angle defined by hitch in groove at juncture with lateral marginal depression, MEW/HuW = 1.81-2.08; parascutellar seta present; parascutellar striole continuous, with 5 small punctures or irregularities along length; sutural interval more convex than lateral intervals, sutural juncture upraised; sutural and 2nd striae of subequal depth from base to apex; discal striae minutely punctured in basal 1/3, smooth and deep apically, associated intervals convex; 7th and 8th intervals of similar convexity mesad subapical sinuation; 2 dorsal elytral setae at 0.31 × and 0.63 × elytral length, setal impressions small, extended over ½ width of interval 3; apical and subapical setae present; lateral elytral setae arranged as anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression moderately narrow throughout length, flat bottomed until subapical sinuation; subapical sinuation evident, moderately deep. Mesepisternum with ~ 14 punctures in two rows; metepisternal width to length ratio = 0.79; metepisternum/metepimeron suture distinct. Abdomen with irregular lateral wrinkles on ventrites 1-5; suture between ventrites 2 and 3 complete; apical male ventrite with 2 marginal setae, and apical female ventrite with 4 equally spaced setae and a median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.19; metatarsomere 4 length along outer lobe 1.4 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci deep, broad, median area medially strigose. Microsculpture of vertex an isodiametric mesh; pronotal disc with transverse mesh, sculpticell breadth 2 –3× length; pronotal median base with distinct to granulate isodiametric mesh; elytral disc and apex with transverse mesh, sculpticell breadth 3 × length, to transverse lines unconnected into a mesh, the apex with more transverse lines; metasternum with distinct transverse mesh; laterobasal abdominal ventrites swirling isodiametric and transverse microsculpture. Coloration of vertex rufobrunneous; antennomere 1 flavous, 2-3 rufoflavous, 4-11 rufobrunneous; pronotal disc rufobrunneous, margins and apex slightly paler, base concolorous; proepipleuron rufoflavous, proepisternum rufobrunneous; elytral disc rufobrunneous; sutural interval rufous basally, rufoflavous apically; elytral marginal depression slightly paler, elytral apex concolorous with disc; elytral epipleuron rufoflavous, metepisternum rufobrunneous; abdomen with ventrites 1-6 medially rufobrunneous, laterally rufoflavous; apical abdominal ventrite 6 with apical half paler, flavous; metafemur flavous; metatibia rufoflavous.

Male genitalia (n = 26). Aedeagal median lobe slender, elongate, distance from parameral articulation to tip 4.1 –5.5× depth at midlength (Fig. 43E, H), but apical extension always smoothly curved relative to median lobe shaft, the apex evenly narrowed to a rounded tip; median lobe broadly curved rightward, the apex blunt in ventral view (Fig. 43C, G); internal sac of variable length (Fig. 43B, F, H), with consistent presence of two ventral microtrichial patches-basal and apical as in Mecyclothorax antaeus (Fig. 34J)-the apical patch of variable size; flagellar plate relatively small, length of sclerotized ventral face 0.33 –0.36× parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with narrow, rounded apex, length 1.17 mm, apical breadth 0.31 mm, basal breadth 0.47 mm subequal to vagina breadth (Fig. 39C); bursal walls translucent with thin wrinkles basally, apical surface shagreened but not wrinkled; gonocoxite 1 with 2-4 apical fringe setae, a moderately sized seta just basad medioapical angle and 7-8 small setae on medial surface (Fig. 37E); gonocoxite 2 narrowly subtriangular with broad apex and tightly rounded tip, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.78 × gonocoxite length.

Holotype.

Female (BPBM) labeled: Kipahulu Valley / Maui Camp 2 / 1250 m, 13-17.VIII.67 // N. Wilson / Collector / BISHOP //? cognatus (E.C.Z. handwriting) // HOLOTYPE / Mecyclothorax / haydeni / Liebherr / J.K. Liebherr 2015 (black-margined red label).

Paratypes.

176 specimens (see Appendix).

Etymology.

This species is named to honor the contributions of Dr. James E. Hayden, Jr. to this project, wherein he dissected numerous male specimens of Hawaiian Mecyclothorax in order to delineate species boundaries.

Distribution and habitat.

Mecyclothorax haydeni occupies ‘Ōhi‘a Forest formations from 1127-2145 m elevation on the wetter, eastern end of the Haleakalā windward forest (Fig. 42). Beetles may be found in leaf litter via sifting, or they may be observed actively running on tree trunks and ferns at night. To date, equivalent samples derived from leaf litter sampling or pyrethrin fogging at 1500-1960 m in Kīpahulu Valley include many more individuals of this species than do samples from 1200 m elevation.