Notagonum chathamense ( Broun, 1909 )

Larochelle & Larivière, Marie-Claude, 2021, Synopsis of the tribe Platynini in New Zealand (Coleoptera: Carabidae), Insecta Mundi 2021 (864), pp. 1-96 : 8-9

Notagonum chathamense ( Broun, 1909)

Fig. 38 , 81 , 155

Anchomenus chathamensis Broun, 1909: 147 . Holotype: “[male symbol]. [ CH] Chatham Islands ” (BMNH, could not be located).

Agonum (Anchomenus) chatamense [sic]: Csiki 1931: 865.

Notagonum chathamensis [sic]: Watt 1980: 334.

Description. Body length 7.3–8.2 mm. Head, pronotum, and elytra mostly piceous black; lateral margins of pronotum and elytra narrowly reddish; abdomen dark rufous; antennae, palpi, and legs dark rufous. Microsculpture isodiametric on head, very transverse (with microlines) on pronotum, and moderately transverse on elytra. Iridescence present on pronotum. Very shiny, with moderate metallic luster (bronze). Head. Mandibles moderately curved anteriorly. Labrum moderately transverse, slightly emarginate anteriorly. Thorax. Pronotum moderately convex, impunctate, feebly wrinkled on disc, moderately wide, subquadrate, widest before middle; apex subtruncate; anterolateral angles poorly developed, rounded; anterior bead incomplete, obsolete medially; sides moderately rounded, not sinuate posteriorly; lateral beads complete; lateral depressions narrow anteriorly, gradually widened posteriorly; posterolateral angles obtuse; laterobasal foveae very deep, moderately wide, not prolonged forward; posterior bead incomplete, obsolete medially; base subtruncate. Legs. Moderately long. Metatarsomeres 5 glabrous ventrally. Elytra. Slightly convex, sloping down toward apex, pear-shaped. Fused along suture (hindwings about half as long as elytra). Shoulders narrow, moderately rounded. Sides strongly rounded. Scutellar striole impunctate. Striae deep, impunctate. Intervals slightly convex; interval 3 with three deep, large (foveate) setiferous punctures. Umbilicate series with 15–16 setiferous punctures. Subapical sinuations feeble. Aedeagus. Lateral view ( Fig. 81 ): strongly arcuate; base moderately convex dorsally, with basal lobe very wide; middle strongly convex dorsally, strongly concave ventrally, without visible dorsal membranous area; apex subtriangular, straight dorsally, slightly concave ventrally, with extreme tip narrow and moderately long.

Material examined. 103 specimens ( AMNZ, JNNZ, LUNZ, MONZ, NZAC).

Geographic distribution ( Fig. 155 ). Offshore Islands: CH.

Ecology. Lowland. Epigean, arboreal. Wet forests (broadleaf) and shrublands; boggy pastures. Shaded or open ground; wet soil. Nocturnal; hides during the day under logs and stones. Gregarious.

Biology. Seasonality: October–November, January–March. Tenerals: January–February. Predacious (based on mouthpart morphology). Occasionally infested with mites and fungi (Laboulbeniales).

Dispersal power. Brachypterous (hindwings half as long as elytra), incapable of flight. Moderate runner. Regular climber (on trees and logs).

Collecting techniques. Turning logs and stones; pitfall trapping.

References. Larochelle and Larivière 2001: 137 (catalogue; biology, dispersal power, ecology, geographic distribution, references), 2007: 114 (list), 2016: 38 (list).

Remarks. The holotype of Anchomenus chathamensis 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 diagnostic characters of the male genitalia, Notagonum chathamense has the following distinguishing features: pronotum subquadrate, apex subtruncate, anterolateral angles poorly developed, sides moderately rounded and not sinuate posteriorly, lateral depressions narrow anteriorly, gradually widened posteriorly; elytra pear-shaped, fused along the suture, shoulders moderately rounded, sides strongly rounded. This species is restricted to the Chatham Islands ( CH).

Figures

Figures 37–40. Dorsal habitus. 37) Platynus macropterus. 38) Notagonum chathamense. 39) N. lawsoni. 40) N. feredayi. Scale line = 1 mm.

Figures 80–86. Aedeagus, lateral. 80) Platynus macropterus. 81) Notagonum chathamense. 82) N. lawsoni. 83) N. feredayi. 84) N. submetallicum. 85) Prosphodrus mangamuka new species. 86) P. waltoni.

Figures 154–159. Species distribution maps. 154) Maoriplatynus marrisi new species. 155) Notagonum chathamense. 156) N. feredayi. 157) N. lawsoni. 158) N. submetallicum. 159) Platynus macropterus.