New records of a lost species and a geographic range expansion for sengis in the Horn of Africa

Abstract

The Somali Sengi or Somali Elephant-shrew (‘Elephantulus’ revoilii, Macroscelidea, Mammalia) has been considered a “lost species” and is primarily known from about 39 museum specimens, with no new vouchered occurrence records since the early 1970s. The scientific literature contains no data concerning living Somali Sengi individuals and the species’ current Data Deficient conservation status is attributable to an absence of modern information. Almost everything that has been published about the species is derived from anatomical examinations of historic specimens, gleaned from museum collection notes, or inferred from the known habits and ecology of other sengi taxa. Here we report new evidence that the Somali Sengi is currently extant. These data include voucher specimens, georeferenced occurrence localities, body measurements, habitat parameters, and DNA sequences. While the species is historically documented as endemic to Somalia, these new records are from the neighboring Republic of Djibouti and thus expand the Somali Sengi’s known range in the Horn of Africa. Furthermore, Djiboutian locality data near international borders suggests that the Somali Sengi is also a current inhabitant of both Somalia and Ethiopia. Criteria that inform conservation status assessments (e.g., suitable habitat contiguity and occurrence in wildlife protected areas) can be positively characterized in Djibouti and therefore bode well for the survival of the Somali Sengi species. New data also inform previously undocumented substrate and sheltering affiliations. DNA analyses indicate that the Somali Sengi is a descendant of the Macroscelidini lineage and therefore reveal that the species’ referral to the genus Elephantulus is incompatible with sengi phylogeny. This taxonomic issue is resolved by recognizing a new genus replacement and recombinant binomial that redesignates the Somali Sengi as Galegeeska revoilii (gen. nov., nov. comb). An analysis of ancestral biogeography suggests that the Somali Sengi has inhabited the Horn of Africa for more than 5.4 million years—and the recognition of the species’ phylogenetic ancestry appends the already remarkable biogeographic story of the Macroscelidini tribe.

The Rufous Sengi is not Elephantulus —Multilocus reconstruction of evolutionary history of sengis from the subfamily Macroscelidinae

“…Our new material was complemented by genetic data from GenBank, collected from 326 elephant shrews from the subfamily Macroscelidinae, most of them from South Africa and Namibia, but we also included recently published sequences of G. revoilii from Djibouti (Heritage et al, 2020) (Table ).…”

“…Males were examined for the presence of nipples (a synapomorphic character of the genera Petrodromus and Petrosaltator ; Olbricht & Stanley, 2009). In addition, we focused on diagnostic traits of G. revoilii and E. rufescens highlighted in Heritage et al (2020) and examined them in our material of E. rufescens . Those characteristics are as follows: size of the second upper incisor (in G. revoilli , it is of the same size as the first and the third incisor, whereas remarkably smaller in E. rufescens ), presence of hairs on tail (in G. revoili , the tail is relatively hairy with a tuft on the distal tip; E. rufescens should have short hairs and lacks tuft), haired inferior part of rhinarium (synapomorphy of G. revoilii and E. rufescens ), and pale eye ring with a dark post‐ocular spot.…”

“…All extant species of sengis are members of a single family Macroscelididae, with two clearly monophyletic subfamilies: Rhynchocyoninae with five species in a single genus Rhynchocyon and Macroscelidinae with 15 species in five genera Macroscelides , Petrodromus , Petrosaltator , Galegeeska , and Elephantulus (Heritage, 2018; Heritage et al, 2020). While the giant sengis from the genus Rhynchocyon are distributed in coastal, montane, and lowland forests of tropical Africa, the members of Macroscelidinae live in more open habitats from woodlands ( Petrodromus ) to semi‐deserts ( Macroscelides ), with the highest species diversity in Southern African region (Heritage, 2018; see also distributional data at https://www.sengis.org/distribution.php).…”

“…In the latter study, Dumbacher (2016) thus defined two tribes in the subfamily Macroscelidinae: Macroscelidini with genera Macroscelides , Petrodromus , and Petrosaltator ; and Elephantulini with species‐rich genus Elephantulus . Finally, Heritage et al (2020) recently rediscovered the very poorly known Somali Sengi ( Elephantulus revoilii ; Huet, 1881) in Djibouti. Subsequent genetic analysis revealed that this species belongs to another distinct evolutionary lineage within Macroscelidini, assigned to the generic name Galegeeska (Heritage et al, 2020).…”

“…Finally, Heritage et al (2020) recently rediscovered the very poorly known Somali Sengi ( Elephantulus revoilii ; Huet, 1881) in Djibouti. Subsequent genetic analysis revealed that this species belongs to another distinct evolutionary lineage within Macroscelidini, assigned to the generic name Galegeeska (Heritage et al, 2020).…”