Ctenognathus oreobius ( Broun, 1886 )

Larochelle & Larivière, Marie-Claude, 2021, Synopsis of the tribe Platynini in New Zealand (Coleoptera: Carabidae), Insecta Mundi 2021 (864), pp. 1-96 : 58-59

Ctenognathus oreobius ( Broun, 1886)

Fig. 78 , 121 , 139

Anchomenus oreobius Broun, 1886: 876 . Holotype: “ one male ” from “ Mount Maungatua , Taieri ” [DN] (BMNH, could not be located).

Agonum (Platynus) oreobium: Csiki 1931: 853 .

Anchomenus oreobius: Hudson 1934: 174 .

Ctenognathus oreobius: Larochelle and Larivière 2007: 81 , 111.

Description. Body length 10.5–13.0 mm. Head, pronotum, and elytra mostly piceous black; posterolateral angles of pronotum and lateral margins of elytra reddish; abdomen piceous black; antennae and palpi dark rufous; femora dark yellow; tibiae and tarsi reddish. Microsculpture isodiametric on head, pronotum, and elytra (elytra almost granulate). Iridescence absent. Head and pronotum very shiny, elytra dull. Forebody moderately wide in comparison to elytra. Head. Moderately wide. Mandibles moderately long and curved anteriorly.Labrum strongly transverse, slightly emarginate anteriorly. Eyes strongly convex; two setiferous punctures on inner side of each eye. Tempora not inflated. Neck constriction absent dorsolaterally. Mentum: medial tooth slightly or moderately emarginate apically; two setae. Submentum with six setae. Palpi with terminal segment obtuse apically. Thorax. Pronotum slightly convex, impunctate, obsoletely wrinkled on disc, wide, moderately cordate, widest before middle; apex strongly emarginate; anterolateral angles well developed, broadly rounded; anterior bead complete; sides moderately rounded, moderately sinuate posteriorly; lateral beads complete; lateral depressions narrow anteriorly, widened posteriorly; two setiferous punctures (anterior and posterior) on each side; posterolateral angles rectangular; laterobasal foveae moderately deep and wide, prolonged forward; posterior bead obsolete; base emarginate. Legs. Moderately long. Metafemora with two posteroventral setae. Meso- and metatarsomeres 1–4 well developed, tricarinate dorsally, deeply bisulcate laterally. Metatarsomeres 4 moderately bilobed, symmetrical apically. Metatarsomeres 5 glabrous ventrally. Elytra. Slightly convex, not sloping down toward apex, oblong, widest about middle. Shoulders moderately rounded. Sides moderately rounded. Scutellar setiferous pore visible. Scutellar striole moderately long, impunctate. Striae deep, impunctate. Intervals depressed; interval 3 with three shallow, minute setiferous punctures. Umbilicate series with 15–18 setiferous punctures. Subapical sinuations feeble. Apices obtuse. Abdomen. Sterna IV–VI: both sexes with two long apical ambulatory setae. Sternum VII (last visible sternum): male with four long apical ambulatory setae; female with ten long apical ambulatory setae. Aedeagus. Lateral view ( Fig. 121 ): strongly arcuate; base moderately convex dorsally, with basal lobe narrow; middle strongly convex dorsally, strongly concave ventrally, with dorsal membranous area strongly widened in apical half and moderately long; apex subtriangular, moderately convex dorsally, slightly concave ventrally, with extreme tip moderately narrow and moderately long. Dorsal view: very wide, asymmetrical (ostium of membranous area deflected to the left); basal bulb moderately distant from membranous area.

Material examined. 107 specimens ( AMNZ, CMNH, JNNZ, LUNZ, MONZ, NZAC).

Geographic distribution ( Fig. 139 ). South Island: CO, DN, MK, SL.

Ecology. Lowland, montane, subalpine, alpine. Epigean. Tussock grasslands, fellfields, adjacent scrublands and forests (podocarp, broadleaf). Mostly open ground; moist or wet soil. Nocturnal; hides during the day under stones, in leaf litter, and under logs. Gregarious.

Biology. Seasonality: September–March. Tenerals: September, March. Predacious (based on mouthpart morphology).

Dispersal power. Subapterous (incapable of flight). Moderate runner.

Collecting techniques. Pitfall trapping; turning stones; sifting leaf litter; turning logs.

References. Larochelle and Larivière 2001: 131 (as “ Anchomenus ” oreobius ; catalogue; biology, dispersal power, ecology, geographic distribution, references), 2007: 81, 111 (as Ctenognathus oreobius ; list), 2016: 37 (list).

Remarks. The holotype of Anchomenus oreobius could not be located in BMNH where Broun’s specimens can usually be found. However, there is no ambiguity regarding the identity of this taxon; the original description can only apply to the species as currently understood. In addition to morphological characters of the male genitalia, Ctenognathus oreobius has the following distinguishing features: antennae dark rufous; terminal segment of palpi obtuse apically; eyes strongly convex; pronotum obsoletely wrinkled on disc, moderately cordate, posterolateral angles rectangular; elytra oblong, sides moderately rounded, striae deep and impunctate. Ctenognathus oreobius occurs mostly in southeastern areas of the South Island (MK to SL, mostly DN and CO).

Figures

Figures 77–79. Dorsal habitus. 77) Ctenognathus davidsoni new species. 78) C. oreobius. 79) C. hoarei new species. Scale line = 1 mm.

Figures 115–122. Aedeagus, lateral. 115) Ctenognathus xanthomelus. 116) C. intermedius. 117) C. colensonis. 118) C. otagoensis. 119) C. earlyi new species.120) C. davidsoni new species.121) C. oreobius. 122) C. hoarei new species.

Figures 136–141. Species distribution maps. 136) Ctenognathus kaikoura new species. 137) C. marieclaudiae new species. 138) C. novaezelandiae. 139) C. oreobius. 140) C. otagoensis. 141) C. perumalae new species.