Actenonyx White, 1846

Kavanaugh, David H., 2022, A New Species of the New Zealand Endemic Genus Actenonyx White, 1846 (Coleoptera: Carabidae: Odacanthini) with Notes on Variation, Distribution, and Habitat, Proceedings of the California Academy of Sciences 67 (11), pp. 281-299 : 283-284

Genus Actenonyx White

Actenonyx White, 1846:2 . Type species: Actenonyx bembidioides White, 1846:2 , by monotypy.

Sphallax Bates, 1867:55 . Type species: Sphallax peryphoides Bates, 1867:56 , by monotypy. Generic synonomy recognized by Bates, 1874:275.

Notes on nomenclature and types. — As Bates (1874) stated when he recognized the synonymy of his genus Sphallax with Actenonyx , “White’s description omits all the essential characters of this curious Carabid [sic], and is so vague that there are no means of identifying it without reference to the type.” Bates’ (1867) description of Sphallax was far more informative and useful.

Diagnosis. — Liebherr (2016) suggested the following combination of features as diagnostic of the monogeneric odacanthine subtribe, Actenonycina: antennomeres 2 and 3 glabrous; genae with a ventral seta present; pronotum with disc bearing shallow transverse wrinkles, lateral setae absent; tarsomeres 5 with reduced ventral setation (only three short ventrolateral setae on each side); and median lobe of male aedeagus evenly narrowed apically.

Examination of the material at hand has shown that two of these features are not universally diagnostic for members of this subtribe and genus. Liebherr recorded antennomeres 2 and 3 as glabrous (his Character 7, state 0). However, in all the specimens I have examined, antennomeres 2 and 3 have at least a few scattered fine setae along their length in addition to the apical whorl of fixed setae (Liebherr’s state 1). In some specimens, the density of this pubescence on the apical half of antennomere 3 is nearly one-third of that of the more distal antennomeres. Although most specimens of Actenonyx have the lateral pronotal setae absent (Liebherr’s Character 36, state 0), some specimens of the new species described below have a single setae present on each lateral margin (Liebherr’s Character 36, state 1) at about the basal one-third (see below for further discussion of the occurrence of this feature).

Two other features recorded in the literature appear to be erroneous. Bates (1867) stated that the male protarsi had four tarsomeres “moderately dilated, triangular; clothed beneath with a dense brush of short hairs”. Among the specimens I have examined, only protarsomeres 1 to 3 are clearly wider than in females and bear pads of adhesive setae ventrally (no pads seen on protarsomere 4). Larochelle and Larivière (2001) listed A. bembidioides as “brachypterous, incapable of flight”. However, all of the specimens of both species of Actenonyx that I have examined have hindwings that are large, apically folded, and with a reflexed tip and should be able to support flight.

Geographical distribution and diversity. — This genus is a New Zealand endemic. It is widely represented on both North and South Islands, but has not been recorded from Stewart Island or any of the Offshore Islands. It includes just two known species, including the second species newly described here.