Mecyclothorax macrops (Sharp)

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 186-187

Taxon classification Animalia Coleoptera Carabidae

(077) Mecyclothorax macrops (Sharp) Figs 95B, 96 A–B, 97A, 98A, 99

Metrothorax macrops Sharp 1903: 270.

Mecyclothorax macrops , Britton 1948b: 119.

Diagnosis.

This species (Fig. 95B) looks much like a smaller version of Mecyclothorax molops (Fig. 95A), but the pronotal hind angles are projected, distinctly obtuse, and the pronotal lateral margin clearly sinuate anterad the angle. The pronotal median base is more punctate, with 20 or more punctures each side that are isolated by glossy cuticle. The sutural stria is easily followed to the basal groove, though it is smooth near the elytral base. The parascutellar seta is absent. The setal formula is 1 0 2 0; anterior supraorbital seta absent. Among Haleakalā species of the group this formula is shared only with Mecyclothorax macrops and Mecyclothorax scarites . At standardized body length 6.1-6.4 mm, these beetles are diagnostically smaller than the former, and diagnostically larger than the latter.

Identification

(n = 4). The pronotum is vase shaped, little transverse, MPW/PL = 1.08-1.13, with the base less constricted than in Mecyclothorax molops ; MPW/BPW = 1.53-1.65. The anterior transverse impression is deep, finely incised, with minute irregularities in the deepest portion. The anterior callosity is convex and crossed by fine longitudinal wrinkles. The elytra are slightly broader basally than in Mecyclothorax macrops , with the basal groove distinctly curved anterad to the subangulate humerus; MEW/HuW = 2.05-2.14. The elytral striae are very reduced apically, with only the sutural interval evident, striae 2-7 absent and traceable only by subsurface punctual remnants. The dorsal body surface bears microsculpture, if much reduced: 1, vertex with very shallow transverse mesh, sculpticell breadth 2 × length; 2, pronotal disc with obsolete transverse lines in part, glossy areas between sculpticells; 3, pronotal median base glossy, with indistinct transverse cells laterally; 4, elytral disc with transverse lines irregularly joined into a loose mesh, apex with shallow transverse mesh, sculpticell breadth 2 –3× length; 5, metasternum with shallow transverse mesh, sculpticell breadth 3 –4× length; and 6, laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture.

Male genitalia (n = 1). Aedeagal median lobe elongate, gracile, distance from parameral articulation to tip 4.0 × depth at midlength (Fig. 96A); apex broadly convex dorsally beyond ostial opening, tip acutely pointed, defined by juncture of convex apical face and downwardly curved ventral margin median lobe straight in ventral view, apex curved and slightly displaced to the right, with right and left margins convergent to pointed tip in this view (Fig. 96B); internal sac with lightly sclerotized macrospicules in position of dorsal ostial microtrichial patch (right side of lobe, Fig. 96B); flagellar plate of moderate size, length 0.37 × parameral articulation-tip distance (estimated from shadow of sclerotized plate in ventral view, Fig. 96B).

Female reproductive tract (n = 1). Bursa copulatrix columnar, elongate, broadest at midlength, length 1.43 mm, midlength breadth 0.51 mm, apical breadth 0.46 mm (Fig. 97A); bursal walls translucent, thickly wrinkled; gonocoxite 1 with 3 apical fringe setae, a thick, curved seta at medioapical angle and 8-9 smaller setae along medial surface (Fig. 98A); gonocoxite 2 very falcate with narrowly rounded tip, base extended laterally in an elongate panhandle with curved terminus; 2 broad, moderately elongate lateral ensiform setae, apical nematiform setae on medioventral surface at 0.61 × gonocoxite length.

Lectotype.

Male (BMNH) hereby designated, labeled: Metrothorax macrops Type D.S. Haleakala Maui 383 // Type // Hawaiian Is. Perkins 1904-336. // LECTOTYPE Metrothorax macrops Sharp J.K. Liebherr 1998 (black-margined red label).

Distribution and habitat.

Mecyclothorax macrops was collected by Perkins from various elevations near Ukulele Camp, however Perkins also collected a single specimen from Olinda from under the bark of a koa tree (Fig. 99), thus expanding the elevational range from 1210-1830 m. Several koa -associated Carabidae in the genus Blackburnia (Tribe Platynini ) suffered catastrophic population declines near the turn of the 20th Century, among them Blackburnia octoocellata (Karsch), Blackburnia sharpi (Blackburn), and Blackburnia terebrata (Blackburn) ( Liebherr 2006). The suggested causes are koa logging and incursion of cattle into the Koa Forest edge-the latter compacting the soil and killing the koa roots-and invasion by alien isopods that occupied the cavities in mature koa trees that would have previously served as daytime refugia for night-foraging carabid beetles.