Mecyclothorax bicoloris, 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 : 272-275

Taxon classification Animalia Coleoptera Carabidae

(108) Mecyclothorax bicoloris sp. n. Figs 143C, 144 D–G, 145B, 146B, 148

Diagnosis.

This species (Fig. 143C) and Mecyclothorax bicoloratus (Fig. 143D) comprise a cryptic sibling species pair diagnosed by: 1, broadly flavous elytral margins contrasted to a rufopiceous disc; and 2, punctate discal elytral striae 1-5. The strial punctures vary in size (Fig. 143 C–D), though unfortunately for the taxonomist, not in tandem with the diagnostic male aedeagal median lobe. The median lobe apex for Mecyclothorax bicoloris males is ventrally pointed (Fig. 144D, F–G), whereas the lobe apex in Mecyclothorax bicoloratus males is broadly rounded (Fig. 144 H–I). Two subtle external characters allow these two species to be diagnosed, though not with the confidence based on a male dissection. Firstly, the microsculpture of the vertex of Mecyclothorax bicoloris individuals comprises an indistinct transverse mesh, sculpticell breadth 2 –3× length, with areas of microsculpture interspersed with glossy areas. The sculpticell margins are not visible in areas of reflected microscope light. Mecyclothorax bicoloratus individuals, in contrast, exhibit a well-developed transverse mesh on the vertex, with the convex surfaces of individual sculpticells discernible, and the entire surface less glossy. Secondly, the elytral lateral marginal groove is narrower basally just laterad the humeral angle in Mecyclothorax bicoloris (Fig. 143C), whereas it is broader with a more elevated margin in Mecyclothorax bicoloratus (Fig. 143D). Setal formula 2 1 2 0. Standardized body length 4.1-4.6 mm.

Description

(n = 5). Head capsule with frontal grooves deepest in anterior half of length where they are parallel on the frons, grooves narrower and shallower posterad a lateral jog in their direction, grooves terminated mesad narrow carina inside anterior supraorbital seta; dorsal impression of neck slightly concave; ocular lobe distinctly protruded from gena, eyes moderately convex and large, ocular ratio = 1.48-1.53, ocular lobe ratio = 0.85-0.91; labral anterior margin angularly emarginate 1/8 of labral length; antennae filiform; antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum transverse, MPW/PL = 1.15-1.29, lateral margins distinctly sinuate for short distance anterad right to slightly acute hind angles, MPW/BPW = 1.56-1.70; median base distinctly depressed relative to disc, with ~20 small, isolated punctures each side; basal margin slightly convex medially, straight behind laterobasal depressions; median longitudinal impression very shallow, middle of disc flat, crossed by indistinct transverse wrinkles; anterior transverse impression broad, shallow, smooth, obso lete medially, incised immediately mesad front angles; anterior callosity nearly flat, slightly convex, smooth; front angles slightly projected, tightly rounded; pronotal apical width slightly greater than basal width, APW/BPW = 1.01-1.09; lateral marginal depression narrow, edge upturned anterad lateral seta, a bit broader at front angle; laterobasal depression narrow with irregular surface, continuous with lateral depression. Proepisternum with 5 minute punctures along hind marginal groove; prosternal process with narrow median impression, lateral margins broadly upraised. Elytra subquadrate, disc slightly convex, sides moderately sloped to margins; basal groove angulate at sutural stria, extended directly to angulate humerus at juncture of basal groove and broader lateral depression, MEW/HuW = 2.04-2.12; parascutellar seta present; parascutellar striole with 5 punctures, striole shallow but continuous between punctures; sutural interval coplanar basally, upraised apically; sutural and 2nd striae of subequal depth and punctation on disc; sutural stria continued to base whereas striae 2-5 obsolete basally; at elytral apex sutural stria deep and smooth, striae 2-3 and 7 traceable apically but very shallow; discal striae 2-6 progressively shallower laterally, punctures more isolated and associated intervals flatter, stria 7 absent at elytral midlength; 8th interval of similar convexity to apical fused portion of striae 5 + 7; 2 dorsal elytral setae at 0.26 × and 0.65 × elytral length, setal impressions small, shallow, spanning ½ 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 narrow laterad humerus with upturned margin, narrower and beaded apically at subapical sinuation; subapical sinuation very shallow, symmetri cal. Mesepisternum with ~9 punctures in 2-3 rows; metepisternal width to length ratio = 0.65; 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 and apical female ventrite with 4 equally spaced setae and median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.19; metatarsomere 4 length along outer lobe 1.3 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, shallow, basal tarsomere medially subcarinate. Microsculpture of pronotal disc shallow transverse mesh to transverse lines between areas of glossy cuticle, median base glossy between punctures, indistinct transverse sculpticells over parts of cuticle; elytral disc with transversely stretched isodiametric sculpticells, sculpticells up to 2 × broad as long, apex with mixture of isodiametric and transverse sculpticells; metasternum with shallow transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse sculpticells. Coloration of vertex rufobrunneous; antennomeres 1-3 flavous, 4-11 rufoflavous; pronotal disc rufobrunneous, lateral margins, base, and apex rufoflavous; proepipleuron rufoflavous, proepisternum dorsally rufoflavous, ventrally rufobrunneous; elytral disc basally rufobrunneous to rufopiceous, lateral margins 7-9 contrastedly flavous, sutural interval rufoflavous basally, flavous apically; elytral apex broadly flavous, the paler area matching or exceeding the breadth of the pale lateral margin; elytral epipleuron flavous dorsally, rufoflavous ventrally, metepisternum rufobrunneous; abdomen with ventrites 1-3 rufobrunneous medially, rufoflavous laterally, ventrites 4-6 basally rufobrunneous, apically flavous; metafemur flavous; metatibia rufoflavous.

Male genitalia (n = 3). Aedeagal median lobe moderately stout, distance from parameral articulation to tip 3.0 × depth at midlength (Fig. 144D, F); apex extended 2 –3× its minimum depth beyond ostial opening, dorsal and ventral margins parallel until tip that is acutely angled and slightly downturned, the apical face convex; median lobe straight, right and left margins similarly convergent in ventral view, the apex with oblique, blunt tip in this view (Fig. 144E); internal sac about twice as long as broad, with broad, diffuse dorsal ostial microtrichial patch near base, and ventral sac surface covered with brownish microspicules (Fig. 144G); flagellar plate of moderate size, length 0.40 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix ovate-like an insect net in profile (Fig. 145B)-with length 0.72 mm, basal breadth 0.51 mm, midlength breadth 0.34 mm; bursal walls translucent, thickly wrinkled; gonocoxite 1 with 3-4 apical fringe setae, a curved seta at medioapical angle and 6-7 setae on medial surface (Fig. 146B); gonocoxite 2 falcate with subacuminate apex, basal extension curved at terminus, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.75 × gonocoxite length.

Holotype.

Male (CUIC) labeled: HI: Maui Haleakala NW / slope Waikamoi Pres. / trans. 3 @ 1700 m el. / 10-IV-1991 sifting / litter J.K. Liebherr // 1 // HOLOTYPE / Mecyclothorax / bicoloris / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui: Haleakala N.P., NW upper slope, beating, 1830-1980 m el., 18-viii-1937, Zimmerman (BPBM, 1); Hanawi N.A.R., Kopiliula Str., pyrethrin fog Metrosideros /moss/uluhe, 1127 m el., 03-v-1998 lot 08 Polhemus (CUIC, 1), Kuhiwa Vy., Poouli Cabin, pyrethrin fog Metrosideros /moss, 1590 m el., 06-v-1998 lot 06, Polhemus (NMNH, 1), pyrethrin fog Metrosideros / roots/trunk, 1590 m el., 06-v-1998 lot 07, Polhemus (NMNH, 1); Koolau For. Res., Kula Pipeline Rd., pyrethrin fog Acacia koa , 1305 m el., 18-v-2003 lot 10, Polhemus (NMNH, 2); Waikamoi N.C.P., pyrethrin fog Metrosideros /moss, 1750 m el., 12-iii-2002, Takumi (BPBM, 1), Honomanu drainage, transect 3, sift moss and litter, 1680-1710 m el., 10-iv-1991 lot 01, Liebherr (CUIC, 1), 08-v-1991 lot 06, Kavanaugh (CAS, 3), scrape Metrosideros humus/moss, 1700 m el., 08-v-1991 lot 03, Liebherr (CUIC, 1), Ukulele Pipeline, pyrethrin fog Metrosideros mossy log, 1510 m el., 16-v-2003 lot 05, Liebherr (CUIC, 2).

Etymology.

The species epithet bicoloris refers to the bicolored elytra of members of this species. The epithet is the genitive singular form of bicolor, and its ending does not change with gender.

Distribution and habitat.

Mecyclothorax bicoloris is distributed on the windward face of Haleakalā from Kuhiwa Stream on the east to the Waikamoi forests on the west (Fig. 148). Localities range in elevation 1305-1980 m. The species was collected once in association with koa , but nearly all records are in association with ‘ōhi‘a; mossy trunks, mossy downed logs and exposed roots, or humus and leaf litter.