Mecyclothorax irregularis Britton

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 79-81

Taxon classification Animalia Coleoptera Carabidae

(029) Mecyclothorax irregularis Britton Figs 44 C–D, 45 D–E, 46A, 47A, 48

Cyclothorax multipunctatus , Blackburn 1878a: 122 (misidentification).

Mecyclothorax irregularis Britton 1948b: 161; Liebherr 2005b, 122.

Diagnosis.

The irregularly anastomosed elytral striae 2-6, combined with the bicolored dorsal surface-piceous head, testaceous pronotum, plus testaceous elytral convexities versus piceous striae (Fig. 44C)-uniquely diagnose this species within the Hawaiian Mecyclothorax fauna. The ventral body coloration is equally distinctive, with the piceous genae, thoracic ventrites, metacoxae, and mediobasal portions of the basal abdominal ventrites distinctly contrasted to the pale mentum and gula, pronotal and elytral epipleura, and abdominal apex (Fig. 44D). Setal formula 2 2 2 2. Standardized body length 4.7-5.2 mm.

Identification

(n = 5). The head is broader relative to the hindbody in this species, MEW/MHW = 1.78-1.90, than in any other species of the group. The broad head is based on a broad head capsule as the eyes are small, ocular lobe ratio = 0.70-0.81, and not very convex, ocular ratio = 1.30-1.39. The pronotal median base is smooth, with the small punctures isolated by areas of granulate isodiametric microsculpture. The laterobasal pronotal depressions are also smooth, shallow, with a broad median tubercle. Microsculpture across the body is well developed, with: 1, vertex, and pronotal disc and base with granulate isodiametric sculpticells, the surface appearing dull; 2, elytral disc and apex with isodiametric sculpticells; 3, metasternum covered with an upraised transverse mesh; and 4, basal abdominal ventrites with lateral areas covered with swirling isodiametric and transverse sculpticells.

Male genitalia (n = 1). Aedeagal median lobe slender, distance from parameral articulation to tip 4.8 × depth at midlength (Fig. 45D); shaft curved basally, nearly straight apically, apex slightly expanded dorsoventrally with rounded tip; median lobe straight in ventral view, left margin distinct incurved to blunt apex, right margin angled leftward to tip (Fig. 45E); internal sac without distinct ornamentation, but surface covered with melanic spicules, short flagellar plate evident in repose, length 0.24 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with rounded apex, length 0.68 mm, breadth 0.23 mm (Fig. 46A); bursal walls translucent, densely wrinkled; gonocoxite 1 with 3 apical fringe setae, and 6-7 smaller setae on medial surface (Fig. 47A); gonocoxite 2 subtriangular, apex acuminate, base evenly extended laterally from lateral margin, 2 lateral ensiform setae with the apical seta longer and broader, apical nematiform setae on medial surface at 0.73 × gonocoxite length.

Holotype.

Female (BMNH) labeled: mounting platen with Blackburn Maui code ( Zimmerman 1957: 210), multip (on reverse) // Type // Hawaiian Is. Rev. T. Blackburn 1883-30 // Cyclothorax irregularis sp. n. E.B. Britton det. 1939.

Distribution and habitat.

This species was described by Britton (1948b) from a single Blackburn specimen originally considered by Blackburn to represent Mecyclothorax multipunctatus . The type locality for Mecyclothorax multipunctatus was listed as "Haleakala, 4000 ft."; i.e. near Olinda. The only modern records derive from the ecologically disjunct forest near Polipoli Springs on Haleakalā’s southwest rift (Fig. 48). Microhabitats at Polipoli where this species has been collected include Dryopteris wallichiana (laukahi) fern litter, deep leaf litter at the bottom of a small rocky face, and the mossy surface of a small, downed Pinus radiata trunk lying in deep leaf litter at the bottom of a shallow ravine.