Mecyclothorax ambiguus (Erichson)

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 ambiguus (Erichson) Figures 2L, 6C, 15C, 16C, 17C, 18C, 19C

Anchomenus ambiguus Erichson, 1842: 130.

Cyclothorax ambiguus Sloane, 1895: 447.

Mecyclothorax ambiguus Sloane, 1920: 153.

Cyclothorax lophoides Sloane, 1895: 447 (misidentification).

Diagnosis

(n = 5). Moore (1984) deferred reliable diagnosis of this species from M. punctipennis based on the configuration of the male aedeagus (e.g. Fig. 15 C–D), however the pronotal lateral margins are reliably narrower in individuals of this species (Fig. 2L). Although variable melanization of the pronotal disc and marginal depressions may confuse the appearance of the width of the lateral depressions, other aspects of the pronotum may be used, including: 1, punctation of the median base, with about 20-22 punctures each side in this species versus nearly 30 deeper punctures each side in M. punctipennis (Fig. 2 L–M); 2, median base juncture with pronotal disc lined with deep, nearly round to moderately elongate punctures in this species, versus distinctly strigose depressions with 1-2 punctures in each depression for M. punctipennis . Microsculpture also varies unambiguously between the two species: 1, in M. ambiguus a transverse mesh visible over portions of the pronotal disc and median base, best viewed adjacent to areas of reflected microscope light, versus glossy pronotal disc and median base, with only indistinct transverse lines within irregularities of the cuticular surface in M. punctipennis ; and 2, discal elytral intervals with well-developed transverse mesh, sculpticell breadth 2 –3× length, and surface subiridescent in M. ambiguus , versus discal elytral intervals glossy, with at most indistinct transverse sculpticells visible at margins of fields of reflected light, the surface without any iridescence in M. punctipennis . The depth of elytral striae varies on the elytral apex, however in M. ambiguus , interval 8 is broadly convex adjacent to the well-developed stria 7 between the subapical and apical elytral setae, whereas in M. punctipennis , interval 8 is internally subcarinate and angularly depressed laterally ( Liebherr 2012a, fig. 7). For M. ambiguus , the mentum tooth has sides obtuse, the apex broadly rounded, whereas M. punctipennis is characterized by an acute mentum tooth with apex tightly rounded. The prosternal anteapical groove is deep and smooth here, but broader and distinctly punctate laterally, though smoother and slightly irregular medially, in M. punctipennis . In addition, the depressions surrounding the dorsal elytral setae span 1/4-1/2 of elytral interval 3 in this species, but up to 1/2-3/4 of the interval width in M. punctipennis . Standardized body length 5.0-5.7 mm. Setal formula ++/++/+2++.

Male genitalia (n = 3). Aedeagal median lobe gracile, narrow dorsoventrally relative to length, apex broad, expanded both ventrally and dorsally resulting in a nearly straight apical face (Fig. 15C); ostial ventroapical operculum well developed as a broadly triangular sclerite; flagellar plate very large, well-sclerotized with longitudinal ridges; aedeagal internal sac bearing a ventral spicular sclerite; right paramere slightly broadened basally, evenly narrowed to apex, ventral surface with ~20 setae along margin, additional very small setae may be present near apex (Fig. 16C); left paramere slightly expanded in basal half, apically narrowed to whip-like apex.

Female reproductive tract (n = 2). Bursa copulatrix elongate, columnar, length about 3 × diameter when pressed under cover slip, surface membranous, translucent, wrinkled (Fig. 17C); spermathecal duct entering bursa copulatrix mediodorsally, duct length about 2 × length of spermathecal reservoir; spermathecal gland duct long,>3 × length of spermathecal reservoir; basal gonocoxite apical margin with 4 setae, 1 setae at apicomedial angle, and several smaller setae along medial margin (Fig. 18C); apical gonocoxite broad basally with 2 short, stout lateral ensiform setae, apex narrowly rounded; apical nematiform setae in sensory furrow near apex of apical gonocoxite.

Type information.

Dissected and pinned male Lectotype (ZMHU): 3294 // ring sclerite and aedeagus on card // ambiguus / Er. / Van Diemens Land / Schayer [blue label] // LECTOYPE (red label) Mecyclothorax / " Anchomenus " / ambiguus / Erichson 1842 / designated by / B. P. Moore. An additional two male and one female paralectotypes (ZMUH) accompany the lectotype.

Distribution and habitat.

This species is distributed throughout southeastern Australia including Tasmania and King Island (Fig. 19C). Localities and repositories for examined material include: NSW: Bodalla (MCZ, 4); Braidwood (MCZ, 41); Breakfast Ck. (MVM, 1); Cabramatta (BMNH, 1); Comboyne plateau (MCZ, 4); Cumberland (BMNH, 1); Greta (AMNH, 1); Kosciuszko N. P. (CUIC, 8; MCZ, 7); Mt. Wilson (FMNH, 1); Narrabeen Lagoon (FMNH, 5); Richmond R. vic. Wiangaree (MCZ, 8); Tallaganda St. For. (CAS, 1); Uralla (CAS, 3); SA: Adelaide (CAS, 1); Adelaide, 18 km E, Carey, 3 km SE (FMNH, 1); Adelaide, 8 km S, Waterfall Gully (FMNH, 1); Blackwood, Sturt Gorge Res. (ZMUC, 13); Goose Island (MVM, 3); Norton Summit, 10 km E Adelaide (FMNH, 2); Williamstown (FMNH, 1); Yorketown (CAS, 2; FMNH, 13); TAS: Burnie (MCZ, 8); Cockle Ck. (MCZ, 2); Florentine R. (MCZ, 3); Goulds Country (CMNH, 2); Hartz N. P. (MCZ, 2); Hastings (MCZ, 3); Hobart (MVM, 3); King Is. (MVM, 2); Launceton (FMNH, 1; MCZ, 1); Mersey R. Vy. (MCZ, 2); Mt. Ben Lomond (MCZ, 6); Mt. Field, base (MCZ, 7); Mt. Wellington (MCZ, 1); Parratah (MVM, 2); Queenstown (MCZ, 16); Smithton (CAS, 7); Tarraleah (MCZ, 3); Waldheim (MCZ, 1); Zeehan (CAS, 1); VIC: Ballarat (BMNH, 2); Bogong (MVM, 2); Dandenong (CAS, 2); Frankston (MVM, 1); Ferntree Gully (MVM, 1); Lakes Entrance (MVM, 1); Mt. Buller (MCZ, 1); Mt. Donna Buang (MCZ, 15); Mt. Hotham (MCZ, 3); Mt. Wogwog (EMEC, 1); Oakleigh (MVM, 2); Olinda (BMNH, 2); Penshurst (CUIC, 7); Port Melbourne (MVM, 2); Portland to Pt. Fairy (MCZ, 2); Pretty Vy. Dam (MVM, 1); Warburton (MVM, 6); Warrendyte (MVM, 1); Whiskey Ck. (MVM, 3); Yarra Glen (MVM, 1).