Mecyclothorax curtus (Sloane)

Liebherr, James K., 2018, Taxonomic review of Australian Mecyclothorax Sharp (Coleoptera, Carabidae, Moriomorphini) with special emphasis on the M. lophoides (Chaudoir) species complex, Deutsche Entomologische Zeitschrift 65 (2), pp. 177-224 : 177

Mecyclothorax curtus (Sloane) Figures 2C, 3C, 7D, 8C, 9C, 10C, 11B

Cyclothorax curtus Sloane, 1895: 448.

Mecyclothorax curtus Sloane, 1903: 585.

Diagnosis

(n = 4). The transverse pronotum–MPW /PL = 1.39-1.47 with nearly impunctate median base and broadly convex margins (Fig. 2C), and broad, subparallel elytra (Fig. 3C), are unique within Mecyclothorax , unmistakably diagnosing this very rarely collected species. The pronotal hind angles are defined by denticles on a more broadly convex margin, the basal pronotal setae associated with a broadened marginal bead at their point of insertion. There are 5-6 minute punctures each side on the median base inside the laterobasal depressions, which are marked by 2-3 oblique lines of larger punctures associated with the depression (Fig. 2C, left side). Ventral prothoracic punctation is restricted to the lateral reaches of the prosternum ( Liebherr 2018, fig. 2D). The lateral margins of the abdominal ventrites are also distinctly punctate, the punctures distributed densely and irregularly enough to give the surface a dented look. As in the above two species, both males and females have 4 setae along the apical margin of the apical abdominal ventrite. As in M. punctatus , the eyes are large and convex, EyL/OLL = 0.87-0.91. However unlike M. punctatus and M. moorei , the elytral striae are fully developed, with all striae evident nearly to the elytral apex. There is a well-developed carina immediately laterad stria 7 that extends from the position of the posterior series of lateral elytral setae to the elytral margin distad the well-developed elytral plica, parsimoniously interpreted as a parallelism also observed in M. blackburni (Fig. 1B, Liebherr 2018, fig. 2L). The apical palpomeres bear a sparse pelage of very short setae, a character otherwise only observed within the genus in Norfolk Islandʼs M. monteithi . Standardized body length 3.8-4.1 mm. Setal formula ++/++/+2++.

Male genitalia (n = 1). Aedeagal median lobe apex narrowly rounded with broad dorsal expansion, the apical face of the lobe concave (Fig. 7D); flagellum short, associated with very elongate sclerotized saccal surface herein interpreted as flagellar sheath (single available male with sac uneverted); right paramere elongate but broad apically (Fig. 8C), the paramere more robust than in other Eucyclothorax (Figs 8, 13), and with ventral surface bearing only a single short seta complementing the 2 long apical setae, and the dorsal surface glabrous; left paramere broad basally (as in males of M. moorei and M. punctatus ), but also broad apically, the apex more than half the breadth of base, a single longer seta present at apex.

Female reproductive tract (n = 1). Bursa copulatrix elongate, columnar (Fig. 9C); helminthoid sclerite with distal projection; spermathecal duct elongate, more than twice length of spermathecal reservoir, the duct moderately sclerotized, undulated along length; basal gonocoxite with a single large seta laterally along apical margin (Fig. 10C); apical gonocoxite very broad, the base extended and recurved basally so that lateral margin is distinctly concave; lateral ensiform setae broad, dorsal ensiform seta situated medially so that its apex extends beyond medial margin; apical nematiform setae in subbasal sensory furrow.

Type information.

Holotype (ANIC): specimen on white triangle, lacking head and prothorax // C. curtus Sl. (type) / Bendigo. W.W.F. / 1176; “1176” is in Sloaneʼs specimen list for 1893/94 (ANIC, unpubl. data).

Distribution and habitat.

The lone holotype was collected by W.W. Froggatt at Bendigo, Victoria. Besides the holotype, I have had the opportunity to examine only a second specimen from Bendigo (MVM), two specimens from Sea Lake, Victoria (Fig. 11B; ANIC, MVM) and a single female from 27 km W Manangatan (ANIC). This last specimen is labeled "South Australia", but based on the locality data it must be from Victoria. Nothing is recorded concerning this speciesʼ habits, though occupation of a terrestrial microhabitat associated with forest vegetation near water would be consistent with the habits of its adelphotaxon, the sister-species pair M. moorei and M. punctatus (Fig. 1B). All specimens are vestigially winged.