Mecyclothorax ambulatus, 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 : 36

Taxon classification Animalia Coleoptera Carabidae

(009) Mecyclothorax ambulatus sp. n. Figs 16 K–L, 20B, 21

Mecyclothorax n. sp. δ, Liebherr 2004: fig. 4.

Diagnosis.

This species exhibits the most somber coloration in the group, the dorsal surface dark fuscous, and antennomeres 1-3 and femora only slightly paler (Fig. 20B). Elytral striae 1-5 are punctate basally, the punctures expanding strial breadth, a characteristic shared with the species triplet, Mecyclothorax waikamoi , Mecyclothorax poouli , and Mecyclothorax ahulili (Fig. 24 B–D), however Mecyclothorax ambulatus exhibits larger body size; standardized body length 4.0 mm versus 2.9-3.4 mm in the other three species. Setal formula 2 1 2 0.

Description

(n = 1). Head capsule with frontal grooves broad near clypeus, a lateral carina present to anterior supraorbital seta; dorsal impression of neck flat to slightly concave; ocular ratio = 1.43, ocular lobe ratio = 0.81; labral anterior margin broadly, shallowly emarginate; antennae filiform, antennomere 2 sparsely setose, antennomere 3 with well-developed pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum with lateral seta present, basal seta absent; MPW/BPW = 1.43; hind angle obtuse, apex rounded; lateral margin slightly divergent anterad hind angle, then more divergent anteriorly; median base moderately depressed relative to disc, sparsely covered with minute punctures, minute wrinkles present at juncture with disc; basal margin convexly expanded between laterobasal depressions; median longitudinal impression narrow, shallowly incised; anterior transverse impression narrow, finely incised, shallowest medially, crossed by fine wrinkles; anterior callosity elevated, flat, crossed by fine wrinkles; front angles slightly projected, tightly rounded; APW/BPW= 1.01; lateral marginal depression narrow, edge upturned anteriorly, beadlike at lateral sinuation and posterad laterobasal depressions; laterobasal depression smooth, continuous with lateral depression. Proepisternum with smooth hind marginal groove; prosternal process medially depressed, sides broadly upraised. Elytra broadly subquadrate; disc moderately convex, sides more so; basal groove recurved to subangulate humeral angle defined by a hitch at base of lateral marginal depression; MEW/HuW = 1.93; parascutellar seta present; parascutellar striole with 3 deep punctures, deep, continuous between punctures; sutural interval more convex than lateral intervals, sutural juncture elevated; sutural and 2nd striae of subequal depth base to apex; striae 1-8 deep, interval 8 convex mesad subapical sinuation; 2 dorsal elytral setae at 0.28 –0.30× and 0.61 –0.63× elytral length, setal impressions moderately deep, spanning 2/3 of interval 3; subapical and apical setae absent; lateral elytral setae arranged in an anterior series of 7 setae and a posterior series of 5 setae; elytral marginal depression broad with upraised margin at humerus, gradually narrowed but still evident before subapical sinuation. Mesepisternum with ~7 punctures in 2-3 irregular rows; metepisternal width to length ratio = 0.80; metepisternum/metepimeron suture distinct. Abdomen with irregular lateral wrinkles on ventrites 1-5; suture between ventrites 2 and 3 reduced, effaced laterally; apical ventrite of male with 2 marginal setae. Legs-metatarsomere 1/metatibial length ratio = 0.19; metatarsomere 4 length along outer lobe 1.33 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, lateral, median area broad. Microsculpture of vertex a well-developed isodiametric mesh in transverse rows; pronotal disc with well-developed transverse mesh, sculpticell breadth 2 –3× length; pronotal median base with well-developed, upraised transverse mesh, sculpticells twice as broad as long; elytral disc with mixture of transverse mesh and transverse lines; elytral apex with mixture of transverse mesh–sculpticell breadth 3 × length–and transverse lines; metasternum with distinct transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex dark rufobrunneous; antennomeres 1-3 rufobrunneous, 4-11 rufopiceous; pronotal disc and margins concolorous, dark rufobrunneous; proepipleuron rufoflavous, proepisternum rufobrunneous; elytral disc dark rufobrunneous, sutural interval concolorous basally, slightly paler, rufoflavous at apex, elytral marginal depression and apex slightly paler, rufoflavous; elytral epipleuron rufoflavous, metepisternum rufobrunneous; abdomen rufobrunneous, apical 1/6 of apical ventrite 6 paler, flavous; metafemur rufobrunneous with piceous cloud covering basal 4/4; metatibia rufoflavous with piceous cast.

Male genitalia (n = 1). Aedeagal median lobe broad, long, distance from parameral articulation to tip 3.3 × depth at midlength (Fig. 16K); apex evenly curved, extended for 3 × its breadth beyond ostial opening, tip slightly flattened on dorsal aspect; median lobe distinctly curved to the right just before blunt apex in ventral view (Fig. 16L); internal sac with dark microspicules over surface, a short flagellar plate visible inside dorsal margin in lateral view.

Holotype.

Male (BPBM) dissected, point mounted above original mounting platen, and labeled: Hal. Maui / 1500 ft. (on reverse) // obscuricolor / var. from lower / elevation. RCLP. // red rectangle // T. obscuricolor // Mecyclothorax / ambulatus / ♂ #1 / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / ambulatus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label). The elevation of 1500 ft. along the Makawao-Paia road is designated the type locality.

Etymology.

The past participle ambulatus means to have travelled or traversed, and is used to signify R.C.L. Perkins’ discovery of the single known specimen at 1500 ft. elevation on Haleakalā. This low elevation collecting site is interpreted to have been along his walk from Makawao, the home base of his mountain collecting, to Paia, the village where he purchased groceries ( Manning 1986).

Distribution and habitat.

Mecyclothorax ambulatus is a biogeographic relict, being labeled from Haleakalā, 1500 ft. by Perkins (Fig. 21). The designated type locality currently lies among agricultural fields and homesites near the town of Kamole, leading to the conclusion that this species is extinct near its only known locality.