Apodecter stromeri, HOPWOOD, 1929

Antoñanzas, Raquel López, Sen, Sevket & Mein, Pierre, 2004, Systematics and phylogeny of the cane rats (Rodentia: Thryonomyidae), Zoological Journal of the Linnean Society 142, pp. 423-444 : 432-433

APODECTER STROMERI HOPWOOD, 1929

Synonymy: Neosciuromys stromeri ( Hopwood, 1929)

The holotype of A. stromeri ( AMNH 22538 ; Fig. 4H) is a right mandibular ramus with m1-m3 from an uncertain Lower Miocene locality of the Namib desert, south of Lüderitz Bay ( Hopwood, 1929) .

Lavocat (1973: 42) reallocated this species to the genus Paraphiomys . Lavocat (1973): 44) noted several differences between the specimens of Paraphiomys stromeri found at Rusinga ( Kenya, Lower Miocene) and those from Songhor ( Kenya, Lower Miocene): the former are smaller and lack the metalophulid II, whereas the lower molars from Songhor frequently show it. Somewhat unusually, Lavocat (1973) considered these differences insufficient to justify a specific distinction, but nonetheless reliable indications for recognizing two subspecies of P. stromeri . Therefore, he coined P. stromeri stromeri to accommodate both the material from Rusinga and the holotype specimen of Apodecter stromeri , and P. stromeri hopwoodi for the sample from Songhor.

We concur with Winkler (1992: 244) in considering that the morphological differences between these two ‘subspecies’ are perfectly adequate to elevate them to the species rank. However, there is no reason to reallocate A. stromeri to Paraphiomys , as Lavocat (1973) did. The Namibian holotype of A. stromeri , which may be 2 Myr older (from rocks deposited 19 Mya), is smaller and more hypsodont than the material from Rusinga ( Mein et al., 2000: 377) assigned by Lavocat (1973) to P. stromeri stromeri . In conclusion, it is not justifiable to consider the holotype of A. stromeri and the remaining specimens of P. stromeri stromeri as representatives of the same species. Therefore, (1) the genus Apodecter is here resurrected, as envisaged by Flynn et al. (1983), (2) a new specific name is given to the material from Rusinga ( P. renelavocati sp. nov.), and (3) the correct name for the material from Songhor is P. hopwoodi .

Incidentally, de Bruijn (1986: 129) reallocated A. stromeri to Neosciuromys . Unfortunately, he did not indicate why, and we judge this combination unjustifiable.

Apodecter stromeri differs from P. pigotti , P. hopwoodi , Paraphiomys sp. nov. from Saudi Arabia, P. occidentalis , Epiphiomys coryndoni and Sacaresia moyaeponsi in lacking the metalophulid II on the lower molars. Apodecter stromeri is much smaller and less hypsodont than N. africanus and P. simonsi . Among other features, it differs from Gaudeamus aegyptius in having an anterolabial cuspid on the lower molars and the hypolophid much less obliquely directed. Apodecter stromeri has the m3 more reduced posteriorly than that of P. orangeus . It is distinct from P. roessneri in having a mesoloph on the P4 and M1 ( Mein et al., 2000: 378). Apodecter stromeri is much smaller than P. australis , Paraulacodus indicus and Paraulacodus johanesi . Finally, A. stromeri mainly differs from P. afarensis in having the m1 and the m2 nearly equal in length, in having an anterolabial cuspid on the lower molars, and in having the hypolophid nearly transverse.