Mecyclothorax argutuloides, 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 : 166-169

Taxon classification Animalia Coleoptera Carabidae

(068) Mecyclothorax argutuloides sp. n. Figs 83D, 84D, 86, 87C, 88 A–B

Diagnosis.

This species (Fig. 87C) looks like a smaller bodied, allometrically more conservative version of its adelphotaxon, Mecyclothorax argutulus (Fig. 81D). Both species share a little transverse, basally broad pronotum; MPW/PL = 1.19-1.22, MPW/BPW = 1.38-1.40 for this species; values that subsume the ratios derived from the unique Mecyclothorax argutulus holotype. However the body proportions of this species are narrower overall, leading to a more gracile appearance. The pronotal lateral marginal depression is narrow at midlength, and although the elytra are narrower in this species than in its robust relative, the elytra are still broader relative to the pronotum; MEW/MPW = 1.39-1.47 versus MEW/MPW = 1.38 in Mecyclothorax argutulus . The elytra tend to have more dorsal elytral setae present, though presence of these setae is also unstable in this species. Of the four specimens available, the setal counts for left plus right elytra are: 4 + 4, 4 + 3, 2 + 3, and 3 + 4; setal formula 2 2 3-4(2) 2. Standardized body length 5.3-5.6 mm, versus 6.2 mm for its closest relative.

Description

(n = 4). Head capsule with frontal grooves broad near clypeus, sinuous, broad convex carina to mesad anterior supraorbital seta; dorsal surface of neck slightly concave; eyes small, little convex, ocular lobe obtusely extended from ocular lobe, ocular ratio = 1.36-1.42, ocular lobe ratio 0.68-0.73; labral anterior margin broadly shallowly emarginate; antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex rounded. Pronotum with lateral margin slightly convergent before acute hind angle, the angle acute even with convexly rounded margin behind angle; median base depressed relative to disc, rugose due to elongate wrinkles and punctures; basal margin broadly extended medially between laterobasal depressions, also convexly expanded posteriorly behind depressions to hind angle; median longitudinal impression finely incised, shallow; anterior transverse impression deeply incised, smooth, anterior callosity broadly convex, the callosity smooth with indistinct longitudinal wrinkles; front angles projected, tightly rounded; apical and basal pronotal widths subequal, APW/BPW = 0.96 -1.02; lateral marginal depression narrow at midlength, broader at front angles, expanded in basal sinuation, margin upturned; laterobasal depression broadly concave, median tubercle present in some individuals. Proepisternum with 6 punctures along hind marginal groove; prosternal process medially concave, margin smoothly upraised. Elytra subquadrate, disc flat, sides moderately sloped; basal groove subangulate at base of sutural stria, extended to tightly angled humerus, the lateral marginal depression broader, its margin more upraised laterad humerus, MEW/HuW 1.75-1.85; parascutellar seta present; parascutellar striole deep, with 3-4 elongate punctures, smooth between punctures; sutural interval convexity only slightly more convex than lateral intervals, sutural juncture upraised at midlength, depressed basally and apically; sutural and 2nd striae of subequal depth from base to apex; discal striae 1-5 present, the median 4 striae continuous, stria 5 partially interrupted, stria 6 reduced and stria 7 only traceable; discal strial punctures minute, only slightly expanding strial breadth and associated with strial irregularities; 8th interval laterad 7th stria of similar convexity to more mesal intervals; up to 4 dorsal elytral setae, at 0.22 –0.24×, 0.38 –0.46×, 0.52 –0.52×, and 0.67 –0.74× elytral length when all are present, setal impressions shallow, spanning about ½ width of interval 3; apical and subapical setae present; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression moderately broad, lined with sculpticells, margin upturned; subapical sinuation shallow, broad. Mesepisternum with ~7 shallow punctures on glossy surface; metepisternal width to length ratio = 0.80; metepisternum/metepimeron suture distinct; the metepisternal ratio is 0.88, and the suture indistinct in the robust adelphotaxon, Mecyclothorax argutulus . Abdomen with shallow indistinct lateral wrinkles on ventrites 1-3; suture between ventrites 2 and 3 complete; apical male ventrite with 2 setae, apical female ventrite with 4 equally spaced setae and median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.18; metatarsomere 4 length along outer lobe 1.4 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci shallow, broad. Microsculpture of vertex a shallow isodiametric mesh in transverse rows; pronotal disc with shallow transverse mesh, median base with distinct isodiametric sculpticells; elytral disc with elongate transverse mesh, apex with reflective transverse mesh; metasternum with reflective transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse sculpticells. Coloration of vertex rufobrunneous; antennomeres 1-3 and base of 4 rufoflavous, balance of antennae with a piceous cast; pronotal disc rufobrunneous with a piceous cast, margins concolorous, depression rufoflavous at front angles; proepipleuron rufoflavous, proepisternum rufobrunneous with piceous cast; elytral disc reflective rufobrunneous, sutural interval concolorous basally, slightly paler apically; elytral margins narrowly rufoflavous in lateral depression, apex broadly paler, rufoflavous; elytral epipleuron rufoflavous, metepisternum rufobrunneous with piceous cast; abdomen rufobrunneous, slightly paler laterally, apical half of apical abdominal ventrite broadly paler, rufoflavous; metafemur rufoflavous; metatibia rufoflavous with brunneous cast.

Male genitalia (n = 1). Aedeagal median lobe robust, dorsal margin flat, distance from parameral articulation to tip 3.7 × depth at midlength (Fig. 88A); apex elongate, with groove extended from ostial opening to downwardly curved, acutely rounded tip; median lobe apex slightly curved rightward in ventral view (Fig. 88B); median shaft broadly expanded medially, maximum breadth 0.32 × parameral articulation-tip distance; internal sac with large dorsal ostial microtrichial patch (right patch in Fig. 88B), and smaller ventral ostial microtrichial patch; flagellar plate of moderate size, length 0.33 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix very elongate, slightly broader in apical half, length 1.37 mm, breadth 0.43 mm (Fig. 83D); bursal walls moderately opaque, thickly wrinkled; gonocoxite 1 with 3-4 apical fringe setae, 2 of the setae larger, the balance smaller (Fig. 84D), 7 smaller setae on medial surface; gonocoxite 2 narrowly falcate, base broadly, moderately extended laterally, 2 broad lateral ensiform setae (apices worn), apical nematiform setae on medial surface at 0.90 × gonocoxite length.

Holotype.

Male (CUIC) labeled: HI:Maui Haleakala N.P. / Kipahulu Vy., 2100 m el. / 7-V-1991 sifting / leaf litter by day // S. Jessel / A.C. Medeiros, /Jr. collectors // Mecyclothorax / argutuloides / ♂ photo / det. J.K. Liebherr 2014 // HOLOTYPE / Mecyclothorax / argutuloides / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

HI: Maui, Haleakala, Upper Hana For. Res., [= Wai‘anapanapa], 2073 m el., 8-v-1973 (BPBM, 1); same data as holotype (CUIC, 2).

Etymology.

The adjectival species epithet argutuloides modifies the epithet argutulus proposed above for a closely related species, leading to a name that signifies "like the small shining" Mecyclothorax argutulus . Again Perrault’s (1984, 1986, 1988, 1989) convention of using a common stem for epithets of closely related species is employed.

Distribution and habitat.

Mecyclothorax argutuloides is known from Wai 'anapanapa, 2070 m elevation in the Hāna Bogs area, and upper Kīpahulu Valley, 2100 m elevation (Fig. 86). The Kīpahulu specimen was collected in a sifted leaf litter sample.