Otomys helleri Frick 1914

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 : 1074

Otomys helleri Frick 1914

Heller’s Vlei Rat

Otomys jacksoni helleri : Frick 1914:10 [type locality— Abyssinia ( Ethiopia), Chilalo Divide Camp, 2743 m]; Allen 1939:345 (listed as valid subspecies); Ellerman 1941:322 (listed as valid subspecies).

Otomys typus helleri : Bohmann 1952

Otomys typus [ helleri ]: Misonne (1974), Yalden et al. 1976, Musser and Carleton 1993

Otomys helleri : Taylor et al. 2011 (new rank).

Otomys jacksoni malkensis : Frick 1914 [type locality— Abyssinia ( Ethiopia), Sidamo , Malka; holotype — CM 3433 ] .

Otomys typus malkensis: Bohmann 1952.

Otomys typus (malkensis): Misonne (1974), Yalden et al. 1976, Musser and Carleton 1993.

Holotype: CM 3519 .

Type locality: Ethiopia, Chilalo Divide Camp, 2743 m a.s.l..

Taxonomic notes: Taylor et al. (2011) elevated the rank of this taxon to a separate species distributed in Bale and Arsi Mts., and possibly farther south (as O. jacksoni malkensis ). We analysed genomically for the first time the populations from central Ethiopia, west of GRV (Guwasa, Debre Sina, Ankober, and Borena Saynt NP) and found them to form a monophyletic group, a sister to O. helleri from Bale and Arsi Mts. Even if they are slightly different in skull morphology ( Fig. 8B ), we suggest they are conspecific. Awaiting genetic analysis of the type of O. degeni from Gombitchu (Shoa), we propose to use the name O. helleri for all of them. The distinctiveness of O. helleri and O. degeni is supported by the morphology of skulls, i.e. the laưer might represent another species ( Taylor et al. 2011: fig. 5; see also above).

Ecological notes: This species prefer patches dominated by Alchemilla in both ericaceous and Afro-alpine habitats ( Kostin et al. 2019).

Distribution: Otomys helleri was described from the Arsi Mts (2743 m a.s.l.) and was considered endemic to Afro-alpine habitats of the Bale and Arsi Mts (3300−4100 m). Here we extended the known distribution of the species to mountains west of GRV, where it inhabits Afro-alpine habitats above 3100 m a.s.l.. This agrees with morphological identification of the species from Ankober ( Taylor et al. 2011). Two specimens from Bongke (Bonke; 3000−3200 m a.s.l.) in the Gughe mountains in southern Ethiopia were also assigned to this species by skull morphology ( Taylor et al. 2011). Even if the elevation corresponds to Afro-alpine habitats, preferred by this species, this geographically distant record in southern Ethiopia requires genetic confirmation.

Figures

Figure 8. Between-group principal components (bgPC) of TYPUS group separating (A) Otomys fortior, O. typus and O. helleri and (B) phylogenetic lineages of O. helleri.Large filled symbols are species means, small open points are individuals, star is O. fortior type specimen (B. S. = Borena Saynt, D. S. = Debre Sina). The skulls of O. typus and O. helleri type specimens are broken.