Mecyclothorax planatus, 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 : 165-166

Taxon classification Animalia Coleoptera Carabidae

(067) Mecyclothorax planatus sp. n. Figs 82 I–L, 83C, 84C, 86, 87B

Diagnosis.

This is the adelphotaxon to Mecyclothorax planipennis , treated immediately above, with the two species synapomorphically united by the anterior and posterior dorsal elytral depressions (Fig. 87 A–B), and by the males possessing four marginal setae on the apical abdominal ventrite. The pronotal base exhibited by members of this species is narrower relative to maximum pronotal width; MPW/BPW = 1.49-1.60, and APW/BPW = 1.06-1.15. The discal elytral intervals within the anterior elytral depression are flatter in this species (Fig. 87B), and the male aedeagal median lobe is bluntly rounded (Figs 82 I–L). Setal formula 2 2 2 2. Standardized body length 5.2-5.7 mm.

Description

(n = 5). As in the taxonomic treatments of other cryptic sibling species pairs in this revision, this description provides only those attributes and measurements that deviate from the description provided above for the sibling species, Mecyclothorax planipennis . Eyes tending to be more convex than in Mecyclothorax planipennis ; ocular ratio = 1.47-1.53, ocular lobe ratio = 0.72-0.80. Pronotum transverse, MPW/PL = 1.30-1.37. Elytra subquadrate, but narrower basally than in Mecyclothorax planipennis , MEW/HuW = 1.91-2.02; discal strial punctures small, little expanding strial breadth within anterior elytral depression; lateral marginal depression extremely narrow at humerus, the lateral margin depression and basal groove similarly upraised laterad and mesad humeral angle.

Male genitalia (n = 5). Aedeagal median lobe robust, distance from parameral articulation to tip 3.2 × depth at midlength (Fig. 82I, K–L); apex little extended beyond ostial opening, flattened on apical face, tip acutely rounded; median lobe curved rightward near apex, right and left margins subparallel near (Fig. 82J); internal sac with small dorsal ostial microtrichial patch and larger, heavily spiculated and projected ventral ostial microtrichial patch (Fig. 82K); flagellar plate very large, length 0.67 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar, length 0.84 mm, breadth 0.46 mm (Fig. 83C); bursal walls translucent, thickly wrinkled; gonocoxite 1 with 4 apical fringe setae and 3 smaller setae on medial surface (Fig. 84C); gonocoxite 2 falcate, base extended laterally, 2 stout, apically narrowed lateral ensiform setae, apical nematiform setae on medial surface at 0.75 × length of gonocoxite.

Holotype.

Male (CUIC) labeled: HI: Maui Haleakala NW / slope Waikamoi Pres. / trans. 3 @ 1700 m el. / 8-V-1991 scraping / ohia w/ moss & dirt // J.K. Liebherr / collector // Mecyclothorax / nsp platysminus / ♂ #1 EM / J.E. Hayden 2005 // HOLOTYPE / Mecyclothorax / planatus / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

91 specimens (see Appendix).

Etymology.

The adjectival species epithet planatus is derived from the Latin planus, flat or level, and signifies the flattened qualities of beetles of this species.

Distribution and habitat.

Mecyclothorax planatus is broadly distributed across the higher elevation forests in the Waikamoi area, with a population known from the western reaches of Ko‘olau Gap (Fig. 86). It can occupy open shrubland such as occurs at Halemau‘u Trailhead (2438 m), or lower-elevation Koa- ‘Ōhi‘a Forest (1210-2438 m). It has been found on koa trunks by scraping the flaky bark, or in moss on ‘ōhi‘a trunks. It has been collected also in sifted litter from ‘Ōhi‘a Forest, as well as under rocks resting on bare soil. That is has been a repeatedly encountered species since G.C. Munro collected a specimen at Olinda in 1936, but was not seen earlier by either Blackburn or Perkins suggests a fundamental change in relative abundances of Mecyclothorax species in this area over the last century.