Otomys typus Heuglin 1877

Mizerovská, Daniela, Martynov, Aleksey A., Mikula, Ondřej, Bryjová, Anna, Meheretu, Yonas, Lavrenchenko, Leonid A. & Bryja, Josef, 2023, Genomic diversity, evolutionary history, and species limits of the endemic Ethiopian laminate-toothed rats (genus Otomys, Rodentia: Muridae), Zoological Journal of the Linnean Society 199 (4), pp. 1059-1077 : 1073

Otomys typus Heuglin 1877

Typical Vlei Rat

Oreomys typus Heuglin 1877: 76 ; Thomas 1891:185 (new species description of Otomys , retention of typus in separate genus). Otomys typus Thomas 1906 , Wroughton 1906, Dollman 1915, Misonne (1974) (no indication rank); Yalden et al. 1976 (no indication rank); Corbet and Hill 1980, 1986, 1991 (no indication of synonym); Honacki et al. 1982 (no indication of synonym), Musser and Carleton 1993 (allocation of synonyms without rank); Yalden et al. 1996 (no indication of synonym).

Otomys typus typus Allen 1939 , Ellerman 1941, Bohmann 1952. Otomys irroratus ( typus ) Delany 1975 (new name combination); Peưer 1982 (allocation of synonym without rank).

Holotype: BMNH 2.9 .9.19.

Type locality: Gonder Province, Simien Mts..

Taxonomic notes: Otomys typus is a monophyletic genomic clade, sister to O. helleri ( Fig. 3 ). Both species are only weakly differentiated, both at their genomes and skull morphology, but we prefer to keep them as two allopatric species, awaiting further studies of their possible contact zones in central Ethiopia ( Fig. 2 ). Specimens from the Chercher Mts. and Hirna (east of GRV) were assigned to O. typus based on morphometric analysis by Taylor et al. (2011), but they instead represent O. helleri , based on phylogeographic paưerns of other taxa (e.g. Mizerovská et al. 2020). We do not include degeni as a synonym of O. typus [contrary to Taylor et al. (2011) and previous taxonomic revisions]. This taxon was described by Thomas (1902) from Gombitchu (8000 ss = 2438 m a.s.l.) in Shoa, not far from Addis Ababa. The morphological analysis of the holotype was inconclusive ( Taylor et al. 2011: fig. 5). Further, the type locality was visited by one of the authors (L.A.L.), and the mid-elevation habitat is very unsuitable for both O. typus and O. helleri . It is also possible that degeni is an available name for O. cf. cheesmani (see that account).

Ecological notes: Otomys typus is an Afro-alpine species preferring alpine moorland, similar to e.g. Stenocephalemys zimai ( Mizerovská et al. 2020) .

Distribution: Otomys typus is restricted to four high-elevation mountain ranges north-west of GRV. Compared to Taylor et al. (2011), we extended its distribution to Choqa and Aboye Gara Mts..

Figures

Figure 2. A, Cytb phylogeny of two groups (the TYPUS and SIMIENSIS groups) of endemic Ethiopian taxa from the O. typus complex. The numbers above the branches indicate BI posterior probability/ML bootstrap support.Maps show the distribution of the mitochondrial diversity in the Ethiopian SIMIENSIS group (B) and TYPUS group (C). Coloured circles indicate the localities with genetically characterized individuals; different colours correspond to six Ethiopian species marked by coloured bars on the right side of the phylogenetic tree.Stars of particular colours show the type localities (there are two stars for O. cheesmani; Dangila is the type locality, the paratype specimen was collected from Gojam). White dots are records of non-genotyped Otomys [based on Yalden et al. (1976, 1996) and the GBIF database; see more details in Bryja et al. (2019a)]. The shades of grey on the map indicate elevation.

Figure 3. ML tree of concatenated SNPs loci developed by ddÞD approach. Numbers above the branches indicate the bootstrap support; coloured bars correspond to six presumed Ethiopian species (for their distribution see Fig. 2B and C). The tree is based on the dataset of 5587 loci and 48 200 SNPs with a minimum 10% occupancy, but the trees from more filtered data had concordant topologies, only with progressively lower support of clades (not shown).