Mecyclothorax bacrionis, 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 : 212-215

Taxon classification Animalia Coleoptera Carabidae

(088) Mecyclothorax bacrionis sp. n. Figs 104D, 105D, 110A, 111, 112

Diagnosis.

This species plus Mecyclothorax haleakalae and Mecyclothorax simpulum comprise the second triplet of Haleakalā’s Mecyclothorax haleakalae group species; this triplet characterized by the glabrous pronotum. In addition to the external key characters of: 1, minutely punctate pronotal median base; and 2, glossy elytral surface without evident microsculpture, this species (Fig. 110A) is easily diagnosed from Mecyclothorax haleakalae (Fig. 110B) and Mecyclothorax simpulum (Fig. 110C) by the foreshortened, more transverse pronotum, MPW/PL = 1.15-1.21. The elytral microsculpture is also less developed in beetles of this species, with the discal surface of the elytra glossy, the surface slightly irregular but without microsculpture. Setal formula 1(2) 0 2 0; the anterior supraorbital seta is present in rare instances. Standardized body length 4.9-5.9 mm.

Description

(n = 5). Head capsule with frontal groove sinuously curved laterally from deep juncture with clypeus to position mesad supraorbital seta; dorsal impression of neck broadly concave, visible dorsally; protruded ocular lobe largely covered by convex eye; ocular ratio = 1.51-1.61, ocular lobe ratio = 0.84-0.91; labral anterior margin shallowly emarginate to 1/8 labral length; antennae filiform, antennomeres 2-3 with extremely short setae to glabrous; mentum tooth narrow, sides acute, apex tightly rounded. Pronotum with basal margin slightly convex medially; median longitudinal impression very finely incised, obsolete on disc, continued deeply on front of median base; anterior transverse impression broad, shallow medially, well incised in lateral halves of each side to front angle; anterior callosity slightly convex, surface minutely irregular due to densely lined longitudinal wrinkles; front angles slightly projected, broadly expanded before tightly rounded margin; pronotal apical width greater than basal width, APW/BPW = 1.05-1.12; lateral marginal depression very narrow, beaded laterally, broader with margin upturned at front angle and outside laterobasal depression; laterobasal depression very narrow, surface irregular, continuation of lateral depression. Proepisternum with 5 distinct punctures along hind marginal groove, small carinae between some of the punctures; prosternal process with broad median depression, lateral margins broadly upraised. Elytra elongate subovoid, disc flat medially, sides distinctly sloped to margins; basal groove curved to angulate humerus defined by hitch at base of marginal depression, MEW/HuW = 2.26-2.44; parascutellar seta present; parascutellar striole with 7 isolated punctures, interrupted between punctures; sutural interval slightly elevated basally, more so apically; discal striae 1-2 shallow, punctate, striae 3-5 a series of punctures, and striae 6-7 absent, sutural stria deep and fine apically, stria 2 obsolete on apex; discal intervals slightly convex on inner intervals, flat laterally; 8th interval laterad 7th stria of same convexity as apical fused portion of striae 5 + 7; 2 dorsal elytral setae at 0.28 –0.30× and 0.58 –0.60× elytral length, setal impressions spanning ½ width of interval 3; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression moderately narrow with upturned edge at humerus, depression lined with isodiametric sculpticells in anterior half, narrowed in apical 1/3 to subapical sinuation; subapical sinuation shallow, symmetrical, internal plica visible from dorsal view. Mesepisternum with ~11 punctures in 2-3 rows; metepisternal width to length ratio = 0.70; metepisternum/metepimeron suture distinct. Abdomen with irregular longitudinal wrinkles laterally on ventrites 1-6, round lateral depressions on ventrites 4-6; suture between ventrites 2 and 3 effaced; apical male ventrite with 2 marginal setae and 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 1.3 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci narrow, lateral, median surface granulate. Microsculpture reduced on vertex, surface glossy with indistinct transverse sculpticells in shallow depressions of the cuticle; pronotal disc glossy, indistinct transverse sculpticells over parts of the surface, median base glossy between the isolated punctures; elytral apex glossy, with indistinct transverse sculpticells along margin; metasternum with shallow transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufous with a piceous cast; antennomere 1 rufoflavous, 2-11 rufobrunneous; pronotum rufopiceous, marginal depression narrowly rufoflavous; proepipleuron rufobrunneous, proepisternum rufopiceous; elytral disc rufopiceous with cupreous reflection, sutural interval concolorous basally, rufoflavous apically; elytral marginal depression rufobrunneous, apex narrowly rufobrunneous apicad subapical sinuation; elytral epipleuron dorsally rufoflavous, ventrally rufobrunneous, metepisternum rufopiceous; abdominal ventrites 1-5 medially rufopiceous, ventrites 3-6 rufoflavous marginally, apical ventrite 6 rufoflavous in apical half; metafemur rufoflavous, apex with rufobrunneous cast; metatibia rufobrunneous.

Male genitalia (n = 5). Aedeagal median lobe gracile, distance from parameral articulation to tip 4.0 –4.3× depth at midlength (Fig. 111 A–C, E); apex elongate, extended 6 × its minimum depth beyond ostial opening, terminated in a spoonlike expanded tip; median lobe apex distinctly curved rightward at 45° angle in ventral view (Fig. 111D), right margin distinctly concave, and left side slightly convex before apex which terminates in a chiseled tip in this view; internal sac with ovoid macrospicular field on right side near base, the ventral surface broadly and diffusely covered with a pelage of microspicules (Fig. 111E); flagellar plate moderately large, length 0.47 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar, narrow and elongate, apex rounded, length 1.20 mm, breadth 0.34 mm (Fig. 104D); bursal walls translucent, thinly wrinkled; gonocoxite 1 with 4-5 apical fringe setae, a thicker seta at medioapical angle and 3-6 smaller setae along medial surface (Fig. 105D); gonocoxite 2 subtriangular, apex tightly rounded, base broadly extended laterally, 2 broad and elongate lateral ensiform setae, apical nematiform setae on medioventral surface at 0.75 × gonocoxite length.

Holotype.

Male (CUIC) dissected and labeled: HI: Maui Haleakala Koolau / For. Res. Koolau Gap @ Halehaku 13-V-1998 / lot03 1325m el. pyr. fog / Cibotium +mossy nurse / log J.K. Liebherr // Mecyclothorax bacrionis / ♂ #4 / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / bacrionis / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui: Koolau For. Res., Hanawi N.A.R., Kopiliula Str., pyrethrin fog Acacia koa trunk, 1127 m el., 03-v-1998 lot 02, Liebherr (CUIC, 3), pyrethrin fog Metrosideros /moss, 1127 m el., 03-v-1998 lot 03, Liebherr (CUIC, 1), beating Metrosideros , 1170 m el., 04-v-1998 lot 05, Ewing (CUIC, 1), Kuhiwa Vy. E rim, dead fronds Cibotium chamissoi , 900 m el., 10-vi-1999 lot 07, Ewing (CPEC, 1), pyrethrin fog Cibotium , 880 m el., 10-vi-1999 lot 05, Polhemus (NMNH, 3), 915 m el., 10-vi-1999 lot 02, Polhemus (NMNH, 5), lot 03, Polhemus (NMNH, 1), pyrethrin fog Metrosideros , 880 m el., 09-vi-1999 lot 04, Polhemus (NMNH, 1).

Etymology.

The species epithet bacrionis , or Latin for ladle with a long handle ( Brown 1956), is here used as a noun in apposition. The epithet references the conformation of the male aedeagal median lobe (Fig. 111).

Distribution and habitat.

Mecyclothorax bacrionis is distributed across the lower elevations-880-1325 m-of Hanawī (Fig. 112). The relatively few records have been associated with ‘ōhi‘a, koa , Cibotium ( hāpu‘u), or soft ferns.