Mecyclothorax splendidus, 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 : 210-212

Taxon classification Animalia Coleoptera Carabidae

(087) Mecyclothorax splendidus sp. n. Figs 102C, 104C, 105C, 108, 109

Diagnosis.

Extremely similar to Mecyclothorax reiteratus , with bisetose pronotum and elytral humeri nearly as narrow; MEW/HuW = 2.39-2.49. The discal elytral intervals are more convex than those of Mecyclothorax reiteratus (Figs 102 B–C), and the pronotal lateral margins are slightly more convergent before the hind angles; lateral margin convergent for 0.12 × pronotal length. The dorsal microsculpture is more developed on beetles of this species, with the pronotal median base bearing a distinct isodiametric mesh across its width, and the elytral disc with a well-developed isodiametric mesh. The configuration of the male aedeagal median lobe is the best arbiter for identification, with the rounded lobe apex more or less symmetrically expanded dorsoventrally in males of this species, even given the infraspecific variation present in this structure (Fig. 108), versus a median lobe apex with a dorsal "crochet hook" expansion in males of Mecyclothorax reiteratus (Fig. 107). Setal formula 2 1 2 0(1)[sae]; the subapical elytral seta is most commonly absent, but present in rare instances. Standardized body length 4.4-5.3 mm.

Description

(n = 5). [The above description of Mecyclothorax reiteratus can serve to describe this species with the following substitutions.] Head with well-developed eyes, ocular ratio = 1.58-1.67, ocular lobe ratio = 0.84-0.90. Pronotum appearing longer than broad, but MPW/PL = 1.04-1.10, base moderately constricted, MPW/BPW = 1.46-1.54; median longitudinal impression finely incised, broadened on median base, crossed by moderately deep transverse wrinkles; anterior transverse impression shallow, broad, surface obscured by deep, dense longitudinal wrinkles; apical pronotal width slightly greater than basal width, APW/BPW = 1.02-1.05. Microsculpture of vertex an indistinct transverse mesh, sculpticell breadth 2 –3× length, cuticle glossy in part; elytral apex with evident isodiametric microsculpture; metasternum with shallow transverse lines to transverse mesh, sculpticell breadth 2 × length.

Male genitalia (n = 18). Aedeagal median lobe gracile, distance from parameral articulation to tip 4.2 –4.7× depth at midlength (Fig. 108A, C–I); apex extended 2 –3× depth beyond ostial opening, slightly expanded dorsoventrally at rounded tip; in ventral view, median lobe slightly curved rightward in apical half, the right and left margins convergent to rounded tip (Fig. 108B); internal sac with broad 1-part (Fig. 108E), or 2-3-part (Fig. 108F, H) dorsal ostial microtrichial patch on right side at base, a transverse band of macrospicules on left side of sac base also present in some individuals (Fig. 108H), ventral sac surface covered with shaggy pelage of microsetae; flagellar plate moderately large, length 0.40 –0.44× parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar, elongate, apex rounded, length 1.03 mm, rounded apex breadth 0.50 mm, basal breadth 0.32 mm (Fig. 104C); bursal walls translucent, apex thinly wrinkled, base more thickly wrinkled; gonocoxite 1 with 6 apical fringe setae, a thick seta at medioapical angle and 5-6 setae along medial surface (Fig. 105C); gonocoxite 2 broadly subtriangular, tip subacuminate, base broadly extended laterally, 2 elongate lateral ensiform setae, apical nematiform setae on medioventral surface at 0.70 × gonocoxite length.

Holotype.

Male (CUIC) dissected and labeled: HI:Maui Haleakala N.P. / Kipahulu Vy. Central / Pali Tr. 1200 m el. / 29-IV-1991 beating / vegetation at night // J.K. Liebherr / A.C. Medeiros, Jr. collectors // HOLOTYPE / Mecyclothorax / splendidus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

108 specimens (see Appendix).

Etymology.

Though hardly unique in its splendidness, this species is given the adjectival epithet splendidus to carry the flag for all species of this hyperdiverse Hawaiian radiation that evolved in splendid isolation ( Simpson 1980, Zevon 1989).

Distribution and habitat.

Mecyclothorax splendidus exhibits a broad, bipartite distribution that includes the Waikamoi forest plus most of the windward face of Maui, including Hanawī, Hāna Bogs, Kīpahulu Valley, and the Manawainui Planeze (Fig. 109). Localities range from 915-2145 m elevation. Recorded forest plant substrates are predomi nantly ‘ōhi‘a and koa , but other recorded plants include Cibotium menziesii ( hāpu‘u), Dubautia (kupoao), Myrsine (kolea), and Pipturus ( māmaki). This species has been repeatedly collected by sifting humus, leaf litter, and moss.