Mecyclothorax subtilis Britton & Liebherr

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 114-115

Taxon classification Animalia Coleoptera Carabidae

(043) Mecyclothorax subtilis Britton & Liebherr sp. n. Figs 60A, 64

Mecyclothorax n. sp. α, Liebherr 2004, fig. 4.

Diagnosis.

This is one of three species in the group that is characterized by bicolored elytra; the lateral elytral intervals flavous, contrasted to the piceous disc (Fig. 60 A–C). In this species intervals 7-9 and the apex of the sutural stria are rufobrunneous to flavous, whereas the basal portions of intervals 2-5 are rufopiceous. The dorsal surface of the head and the pronotum are rufous with a flavous cast. The pronotum is moderately transverse, MPW/PL = 1.26, and basally constricted, MPW/BPW = 1.58. The dorsal surface of the head bears well-developed isodiametric sculpticells arranged in transverse rows. The setal formula is 2 1 2 0; the other two bicolored species- Mecyclothorax patulus and Mecyclothorax patagiatus -are characterized by presence of the subapical seta. Moreover, this species lacks the parascutellar seta, whereas it is present in the other two species. Standardized body length 3.45 mm.

Description

(n = 1). Head capsule with frontal grooves broad near clypeus, convexity present laterad groove, a narrow carina extended to supraorbital seta; dorsal surface of neck flat; eyes large, moderately convex, ocular ratio = 1.46, ocular lobe ratio = 0.84; labral anterior margin very shallowly emarginate medially; antennae filiform, antennomeres 2-3 glabrous except for 1 or 2 small setae on shafts; mentum tooth with sides acute, apex tightly rounded. Pronotum with glabrous hind angles, the base constricted, and lateral margins subparallel anterad the right, projected hind angles; median base moderately depressed, strigose due to long punctures and wrinkles; basal margin straight medially, margin expanded posterad laterobasal depressions; median longitudinal impression shallow, finely incised; anterior transverse impression shallow, broad, crossed by indistinct wrinkles; anterior callosity elevated, flat, crossed by indistinct longitudinal wrinkles; front angles projected, tightly rounded; pronotal apex broader than base, APW/BPW = 1.06; lateral marginal depression narrow, edge slightly upturned, broader at front angle, beaded anterad basal sinuation; laterobasal depression smooth, continuous with lateral depression; slight tubercle mesad lateral margin. Proepisternum with 5 minute punctures along hind marginal groove; prosternal process with narrow median impression, lateral margins broadly beaded between coxae. Elytra subellipsoid, disc flat, sides moderately sloped; basal groove slightly recurved to tightly rounded humeral angle; greatest width near midlength, MEW/HuW = 2.09; parascutellar striole discontinuous along length, with 3-4 punctures; sutural interval coplanar with lateral striae basally, upraised in apical half; sutural and 2nd striae of subequal depth from base to apex; discal striae 1-5 broad but defined, lined with minute elongate punctulae in basal 1/3 of length, 6-7 discontinuous, represented by serial punctures, discal intervals moderately convex; 8th interval slightly more convex than fused apical portion of fused striae 5 + 7; 2 dorsal elytral setae at 0.28 × and 0.64 × elytral length, setal impression small, spanning 1/3-1/2 of interval 3; apical and subapical setae absent; lateral elytral setae arranged in an anterior series of 6 setae and a posterior series of 5 setae; elytral marginal depression narrow, margin little upturned in basal half, narrowly beadlike near subapical sinuation; subapical sinuation very shallow, nearly obsolete. 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; suture between ventrites 2 and 3 complete; apical female ventrite with 4 equally spaced marginal setae plus median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.20; metatarsomere 4 length along outer lobe 1.33 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, shallow, median surface broad. Microsculpture of pronotal disc transverse mesh, sculpticell breadth 2 × length, median base with mixture of isodiametric and transverse sculpticells; elytral disc with transverse mesh, sculpticell breadth 2 –4× length, apex with shallow transverse mesh of the same dimensions; metasternum with shallow transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of antennomere 1 flavous, antennomeres 2-3 rufoflavous, 4-11 rufobrunneous; proepipleuron and proepisternum rufoflavous; elytral epipleuron rufoflavous, metepisternum rufobrunneous; abdomen with ventrites 1-3 medially pale rufobrunneous, lateral portions and ventrites 4-6 rufoflavous; femur rufoflavous; tibia rufoflavous with rufous cast.

Female reproductive tract. The lone female holotype was not dissected.

Holotype.

Female (BPBM) labeled: Haleakala / 5000 ft. / April / RCLP (obverse of mounting platen) / 369 (on reverse of platen) // Type (round red-margined label) // sp. n. near Mecyclothorax ovipennis // 1323 // HOLOTYPE / Mecyclothorax / subtilis / E.B. Britton / det. 1940 // HOLOTYPE / Mecyclothorax / subtilis Britton / & Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Etymology.

Britton’s choice of the Latin adjective subtilis to signify the minute, slender body of this beetle was extremely appropriate, and that choice is hereby validated.

Distribution and habitat.

Perkins’ lot 369 was collected on 10-iv-1894 at 5000 ft. (1524 m) elevation ( Anonymous N D). The only relevant field note from that day (Perkins, 1894) states "Picked up a good number of Carabids, …” As Perkins made no mention of straying far from camp, Ukulele Camp (Site) is designated the type locality (Fig. 64).