Ctenognathus arnaudensis
Creators: name: Larochelle
name: Larivière, Marie-Claude
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Ctenognathus
Ctenognathus arnaudensis

description: Ctenognathus arnaudensis (Broun, 1921)   
Fig. 66, 109, 125  
 Anchomenus arnaudensis Broun, 1921: 598. Holotype: “[male symbol] [BR] Mt St Arnaud, Nelson ” (BMNH, could not be located).   
 Agonum (Anchomenus) arnaudense: Csiki 1931: 865.   
 Anchomenus arnaudensis: Hudson 1934: 174.   
 Ctenognathus arnaudensis: Larochelle and Larivière 2007: 81, 111.   
 Description. Body length 10.1–10.6 mm. Head, pronotum, elytra, and abdomen piceous black; antennal segments 1–3 reddish black, 4–11 dark rufous; palpi reddish; femora and tibiae dark rufous; tarsi rufotestaceous. Microsculpture isodiametric on head, moderately transverse on pronotum and elytra. 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, moderately emarginate anteriorly. Eyes strongly convex; two setiferous punctures on inner side of each eye. Tempora not inflated. Neck constriction shallow dorsolaterally. Mentum: medial tooth slightly emarginate apically; two setae. Submentum with six setae. Palpi with terminal segment obtuse apically. Thorax. Pronotum slightly convex, impunctate, obsoletely wrinkled across base, wide, subrectangular, widest before middle; apex slightly emarginate; anterolateral angles moderately developed, moderately rounded; anterior bead complete; sides moderately rounded, not sinuate posteriorly; lateral beads complete; lateral depressions wide, much more so posteriorly; two setiferous punctures (anterior and posterior) on each side; posterolateral angles obtusely rectangular; laterobasal foveae very deep and wide, prolonged forward; posterior bead incomplete, obsolete medially; base subtruncate. 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, sloping down toward apex, oblong, widest behind middle. Shoulders moderately rounded. Sides slightly rounded. Scutellar setiferous pore visible. Scutellar striole moderately long, impunctate. Striae shallow, impunctate. Intervals subdepressed; interval 3 with three or four very deep, large (foveate) setiferous punctures. Umbilicate series with 16–17 setiferous punctures. Subapical sinuations feeble. Apices obtusely rounded. 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 eight long apical ambulatory setae. Aedeagus. Lateral view (Fig. 109): strongly arcuate, very wide medially, stout; base strongly convex dorsally, with marginal blade instead of basal lobe; middle strongly convex dorsally, strongly concave ventrally, with dorsal membranous area very wide in apical half and very long; apex subtriangular, slightly convex dorsally, slightly concave ventrally, with extreme tip triangular 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. 15 specimens (BMNH, CMNZ, MONZ, NZAC).   
 Geographic distribution (Fig. 125). South Island: BR –Lake Rotoiti. Mount St Arnaud. KA–Williams Stream. MB –Judges Creek. Shroders Creek (Upper Wairau Valley). NN –Beebys Knob. Kaituna River (near Aorere). Nelson.   
 Ecology. Lowlands, montane. Epigean. Dry forests (beech). Shaded ground; dry soil. Nocturnal; found under a log and a matagouri bush.   
 Biology. Seasonality: September–October, January–February, June. Predacious (based on mouthpart morphology).   
 Dispersal power. Subapterous (incapable of flight). Moderate runner.   
 Collecting technique. Hand-collecting.   
 References. Larochelle and Larivière 2001: 130 (as “ Anchomenus ” arnaudensis; catalogue; biology, dispersal power, ecology, geographic distribution, references), 2007: 81, 111 (as Ctenognathus arnaudensis; list), 2016: 36 (list).   
 Remarks. The holotype of Anchomenus arnaudensis 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. Furthermore, a nontype female specimen from the Broun Collection (BMNH) was examined. This specimen is from Lake Rotoiti (BR) at St Arnaud next to the St Arnaud Range and its morphology corresponds to Broun’s original description of Anchomenus arnaudensis. In addition to diagnostic characters of the male genitalia, Ctenognathus arnaudensis has the following distinguishing features: femora and tibiae dark rufous; pronotum subrectangular, base subtruncate; elytra slightly convex, microsculpture moderately transverse, striae impunctate. Ctenognathus arnaudensis occurs in dry beech forests from northern areas of the South Island (NN, BR, MB, KA).
description: Published as part of Larochelle & Larivière, Marie-Claude, 2021, Synopsis of the tribe Platynini in New Zealand (Coleoptera: Carabidae), pp. 1-96 in Insecta Mundi 2021 (864) on pages 45-46, DOI: 10.5281/zenodo.5041813