Onymacris paiva (Haag-Rutenberg 1875) Dull Three-ribbed Namaqua Darkling

A black Onymacris without white waxy secretions. Pronotum dull, with large rounded punctures laterally. Elytral disc with three distinct costae, with strong, backwardly directed denticular granules; distinct secondary costa not developed. Meso tibiae subcylindrical, tarsal claws very slender.

Several subspecies have been described (Koch 1948), of which Penrith (1975) recognized two, O. paiva paiva from the northern Namaqualand/Richtersveld coast north of the Buffels River, and O. paiva conjuncta from south of the Buffels River.
Illustration of different elytral patterns from Koch 1948:

Penrith 1984 describes the 2 recognized subspecies as follows (this does however not agree with the subspecies outlined by Haag-Rutenberg and Koch 1948):

Onymacris paiva paiva: First elytral costa uniting with second before or at top of apical declivity; apical declivity between united costae usually with short transverse anastomosing costae.

Onymacris paiva conjuncta: First elytral costa either not uniting with second, which terminates freely before junction of first and third costae, or uniting with second on apical declivity; apical declivity between united costae without transverse costae.

Original description in:
Haag-Rutenberg, G. J. 1875. Beiträge zur näheren Kenntniss einiger Gruppen aus der Familie der Tenebrioniden. Deutsche Entomologische Zeitschrift 19(7): 1-56.
https://www.digitale-sammlungen.de/view/bsb11323431?page=486
Elongated, black, slightly shiny; with a large head; between the eyes with a carina, impressed, almost smooth; pronotum very sharply cut out, shiny, disc almost smooth, sides punctured; elytra oblong, the margins and three carinae joined together, elevated, loosely crenulate; legs very long, black, with very large, black-brown spurs and claws.
Length 16-18 mm; width 8-9 mm.

Onymacris paiva confluens illustrated in:
Koch C. 1955. Monograph of the Tenebrionidae of southern Africa Vol I (Tentyriinae, Molurini Trachynotina: Somaticus Hope). Transvaal Museum Memoir 7
Plate 1: https://journals.co.za/doi/pdf/10.10520/AJA0000012_541

Distribution: Northern Cape, South Africa; Succulent Karoo along the coast.

iNat observations:
https://www.inaturalist.org/observations/97148209
https://www.inaturalist.org/observations/82980029
https://www.inaturalist.org/observations/73333470
https://www.inaturalist.org/observations/19422621
https://www.inaturalist.org/observations/10830856
https://www.inaturalist.org/observations/10830634

References:
Key and distribution maps for Onymacris in Penrith 1984:
https://journals.co.za/doi/pdf/10.10520/AJA00411752_156

Koch, C. 1948. The Tenebrionidae of Southern Africa. VII. Preliminary notes on the South African Adesmiini. Annals of the Transvaal Museum 21.
https://journals.co.za/doi/pdf/10.10520/AJA00411752_427
Plate 23, figures 11-20 https://journals.co.za/doi/epdf/10.10520/AJA00411752_431

Publicerat 24 april 2024 16.35 av traianbertau