Mecyclothorax minor 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 : 175-176

Taxon classification Animalia Coleoptera Carabidae

(071) Mecyclothorax minor Britton Figs 90B, 91C, 94

Mecyclothorax minor Britton 1948b: 154.

Diagnosis.

This species (Fig. 90B) and Mecyclothorax angusticollis (Fig. 90C) represent the two species of the Mecyclothorax microps group characterized by: 1, a quadrate, basally broad pronotum, MPW/BPW = 1.30-1.35; 2, both anterior and posterior dorsal elytral setae present; and 3, elytra that are narrow relative to the forebody, MEW/MPW = 1.35-1.44, MEW/MHW = 1.93-2.12. Britton distinguished his Mecyclothorax minor from Mecyclothorax angusticollis based on the paler body color, and the broader pronotal base with non-sinuate lateral margins anterad the obtuse hind angles. Setal formula 2 2 2 0. Standardized body length 3.7 mm.

Identification

(n = 1). The eyes are small, ocular ratio = 1.36, but cover much of the non-protruded ocular lobe, ocular lobe ratio = 0.79. The labrum is medially emarginate to 1/5 labral length. The pronotal median base is nearly coplanar with disc, and covered with 8-10 minute, isolated punctures each side. The laterobasal depressions are not present, with that area broadly convex to the narrow lateral and basal margins. The elytra are narrow, with the basal groove distinctly recurved on the tightly rounded humeri, MEW/HuW = 1.80. The sutural and 2nd striae are of equal development throughout their length, whereas striae 3-4 are of similar depth and punctation on the disc. Striae 5-6 are shallower and less punctate, and stria 7 shallower still and interrupted along its length. The 2 dorsal elytral setae are placed at 0.26 –0.30× and 0.59 –0.61× elytral length, with the setal impressions spanning half of interval 3. The vertex is covered with a shallow isodiametric and transverse mesh, sculpticell breadth 2 × length; pronotal disc with transverse mesh, sculpticell breadth 2 –4× length, the median base with mixture of isodiametric and transverse sculpticells; and elytral disc with transverse mesh, sculpticell breadth 3 –4× length, and transverse lines, the apex with mixture of transverse sculpticells and parallel lines.

Male genitalia (n = 2). Aedeagal median lobe moderately gracile, distance from parameral articulation to tip 3.7 × depth at midlength (Fig. 91C); apex extended for twice breadth beyond ostial opening, flattened on apical face, tip narrowly rounded; internal sac with a well-developed dorsal ostial microtrichial patch present, ventral surface broadly covered with microspicules; flagellar plate moderately large, length 0.45 × parameral articulation-tip distance.

Holotype.

Male (BMNH), dissected and labeled: Type (round red-margined label) // Haleakala, / Maui 5000ft. / Perkins. V 1896 // near microps // Sharp Coll. / 1905-313. // Hawaiian Is. / R.C.L. Perkins. // Cyclothorax / minor sp. n. / E.B. Britton / det. 1939.

Distribution and habitat.

Mecyclothorax minor was collected in Perkins’ lot 600 ( Anonymous N D) consistent with a collecting locality near Ukulele Camp (Fig. 94). It has not been collected since, though the mesic forest surrounding Ukulele Pipeline near that elevation has been visited on several occasions.