Mecyclothorax longulus 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 : 102-104

Taxon classification Animalia Coleoptera Carabidae

(038) Mecyclothorax longulus Sharp Figs 52C, 53 E–F, 54C, 55C, 56

Mecyclothorax longulus Sharp 1903: 251; Britton 1948b: 143.

Diagnosis.

It is the narrow, parallel-sided body shape (Fig. 52C) that diagnoses this species. The quadrate, elongate elytra exhibit only slightly convex lateral margins and relatively broad humeri, MEW/HuW = 1.83-1.93, and the pronotum is very broad relative to the elytra, MEW/MPW = 1.33-1.36. In this group, only Mecyclothorax consobrinus (Fig. 57B) and Mecyclothorax sobrinus (Fig. 57C) exhibit such quadrate elytra, but their body sizes are much larger; standardized body length for these two species spans 5.5-6.6 mm versus a standardized body length of 5.1-5.3 for Mecyclothorax longulus . Setal formula 2 2 2 2.

Identification

(n = 4). As above for the pronotum, head broad, MEW/MHW = 2.00-2.06, the eyes moderately convex, ocular ratio = 1.40-1.46. The lateral margins of the pronotum are only slightly sinuate anterad the obtuse, non-projected hind angles. The pronotal median base is indistinctly punctate, with 8-11 distinct rounded punctures or elongate longitudinal wrinkles each side, and the smooth laterobasal depression has a broad median tubercle. The discal elytral striae are minutely punctate, with associated intervals 1-5 slightly convex. The elytral setae consist of the parascutellar seta, 2 dorsal elytral setae at 0.33 –0.35× and 0.60-0.62 and 0.60 –0.62× elytral length, apical and subapical setae, and lateral setae arranged in an anterior series of 7 setae plus a posterior series of 6 setae. The dorsal microsculpture includes: 1, vertex with an upraised isodiametric mesh in transverse rows; 2, pronotal disc with upraised transverse mesh, sculpticell breadth 2 × length, the median base with granulate isodiametric sculpticells intermixed with some transverse sculpticells; 3, elytral disc with an upraised isodiametric mesh, the apex with the isodiametric and slightly transversely stretched sculpticells in transverse rows.

Male genitalia (n = 1). Aedeagal median lobe gracile, distance from parameral articulation to tip 4.3 × depth at midlength (Fig. 53E); apex extended 3 × its depth beyond ostial opening, apex expanded dorsoventrally with ventral margin convex before round ed tip; median lobe distinctly curved to right in ventral view distad apex of ostial opening (Fig. 53F); internal sac covered with dark fields of microspicules, short flagellar plate visible inside dorsal margin of lobe, length 0.26 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar, short and broad, the dimensions dictated by a heavily sclerotized, hemi-elliptical plate dorsad bursa copulatrix-median oviduct juncture, bursal length 0.48 mm, breadth 0.40 mm, the same dimensions as bursal sclerite (Fig. 54C); bursal walls translucent with thin wrinkles where not sclerotized into bursal sclerite; gonocoxite 1 with 3-4 apical fringe setae, 6-7 smaller setae on medial surface (Fig. 55C); gonocoxite 2 subfalcate with tightly rounded apex, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.77 × gonocoxite length.

Holotype.

Male (BMNH) labeled: Mecyclothorax longulus Type D.S. Haleakala Perkins 120 // Type // Hawaiian Is. Perkins 1904-336. // Haleakala Maui 5000 ft. 6 IV 1894 // HOLOTYPE Mecyclothorax longulus Sharp J.K. Liebherr 1998 (black-margined red label).

Distribution and habitat.

Mecyclothorax longulus is known from Koa- ‘Ōhi‘a Mesic Forest across a very limited geographic area west of Pu‘u o Kakae-elevations 1425-1615 m-in the Waikamoi area (Fig. 56). It was described by Sharp (1903) from a unique specimen from Ukulele Camp, and it has been recollected on four occasions since. It has been found in leaf siftate, by grubbing in leaf litter, under the rotten bark of Cheirodendron ('ōlapa), and in a yellow-pan trap.