A realistic approach to subspecies-identification in the springbok

Naturalists interested in the subspecies of the springbok (Antidorcas marsupialis) should read https://www.zobodat.at/pdf/Zeitschrift-Saeugetierkunde_46_0189-0197.pdf. Although now forty years old, Groves (1981) is still the best reference on a topic which will probably never be resolved satisfactorily.

Zoologists failed to document the nominate subspecies. The Karoo springbok (Antidorcas marsupialis marsupialis) occurred in Namaqualand, the Karoo, Eastern Cape, Free State, Gauteng, and the southern part of Northwest Province, with possible extensions into Mpumalanga, Limpopo, and even Kwazulu-Natal Provinces. Despite the extreme abundance of this form, the museums of the world have virtually no study-skins and only a few skulls. The Karoo springbok was, like the quagga (Equus quagga quagga), taken for granted until it was too late; and far fewer specimens were collected scientifically than for the quagga.

We cannot know exactly what subspecies marsupialis looked like in its original, fully wild condition. It is technically extinct because artificial reintroductions failed to discriminate against subspecies hofmeyri of the Northern Cape, and then there has been nearly a century of advertent and inadvertent selective breeding by farmers, partly to promote mutant genotypes. Body size is too adaptable to mean much, and the facial colouration varies individually in all the subspecies.

South Africa has thus lost its national mammal as a subspecific genetic entity, and more unfortunately we can never define what that entity was in the first place. Our best guess, based on a south-north cline from the northeastern Karoo to Angola (Groves 1981), is that the springbok of the Klein Karoo and Eastern Cape had extremely short, smooth horns in the female, and was not as pale as conspecifics in the Kalahari.

Groves found only 33 study-skins of the whole species of the springbok to examine in the museums of the world, and ironically 39% of these came from Angola and Kaokoland, which remain so remote that iNaturalist still features few photos from these areas. More particularly, we have the odd situation that subspecies angolensis is the best-represented of all the subspecies in terms of study-skins (13 of the 33 specimens examined by Groves), but so poorly represented photographically that to this day no photo shows clearly the darkness of colouration which Groves found relative to subspecies hofmeyri south of the Kunene River, in Kaokoland (also surprisingly well-represented, by 7 study-skins).

The false notion that angolensis extends to northern Namibia, including Etosha, seems to have arisen in Cain et al. (2004) Mammalian Species no. 753 (available free on the Web). Although ostensibly an authoritative summary of the springbok, this misportrayed the subspecies in its distribution map.

My suggestion for iNaturalist: for photos from Angola, assume angolensis; for photos from the Namib, northern Namibia, Botswana and the Kgalagadi Transfrontier Park, assume hofmeyri; and for all other locations just identify to species-level because the subspecies-status has been irretrievably compromised.

Publicado por milewski milewski, 06 de mayo de 2021

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