Brachyuromys Major, 1896

Denys, Christiane, Gabriel, Nadine W., Lalis, Aude & Jenkins, Paulina, 2024, Subfossil rodents and tenrecs of Children’s Cave, Madagascar, Journal of Natural History 58 (25 - 28), pp. 796-839 : 801

Genus Brachyuromys Major, 1896

Today in Madagascar there are two recognised species, Brachyuromys ramirohitra Major, 1896 and Brachyuromys betsileoensis ( Bartlett, 1880) , both ranked as Least Concern on the International Union for Conservation of Nature (IUCN) Red List ( Goodman et al. 2013). According to Soarimalala and Goodman (2011), B. betsileoensis is smaller and is distinguished easily by external characters. Ellerman (1941) provided an identification key with some dental characters for the genus, among which were the flat-crowned cheekteeth, with curved folds becoming isolated with wear. According to him B. ramirohitra molars are flatter and their folds become isolated at a very early age, while in B. betsileoensis this condition is not reached until old age. Brachyuromys ramirohitra has a larger m3 than B. betsileoensis . Petter (1961) also recognised the same size and morphological differences between molars of the two species. Currently although both species are known from separate locations in the Central Highlands of Madagascar, defined as the interior region of the island greater than 900 m above sea level ( Goodman and Soarimalala 2018; Denys et al. 2021), they are only sympatric in Andringitra and Ampitambe ( Goodman and Rasolonandrasana 2001; Jenkins and Carleton 2005).

Some of the Children’s Cave specimens were labelled ‘ Brachyuromys arvicoloides ’ Maj. but the species was never described and is a nomen nudum. According to Jenkins and Carleton (2005), during his fieldwork Major provisionally recognised the presence of two species within the genus that he was later to formally name as Brachyuromys , using the label names of B. ramirohitra and B. ‘ arvicola ’. Evidently Major recognised that taxa which he had provisionally named ‘ arvicola ’ and ‘ arvicoloides ’ were synonyms of Nesomys betsileoensis Bartlett, 1880 but formulated Brachyuromys as a new genus in recognition of the incorrect generic allocation to Nesomys . In his original description of B. ramirohitra, Major (1896a) indicated the presence of this species in the lower deposits of the Children’s Cave (Sirabé).

In order to verify the presence of one or two species of Brachyuromys in the cave and their specific attribution we compared them with modern representatives of the genus. We confirm here the presence of two Brachyuromys species in Children’s Cave.