Pelomedusa somalica, Petzold & Vargas-Ramírez & Kehlmaier & Vamberger & Branch & Preez & Hofmeyr & Meyer & Schleicher & Široký & Fritz, 2014

Petzold, Alice, Vargas-Ramírez, Mario, Kehlmaier, Christian, Vamberger, Melita, Branch, William R., Preez, Louis Du, Hofmeyr, Margaretha D., Meyer, Leon, Schleicher, Alfred, Široký, Pavel & Fritz, Uwe, 2014, A revision of African helmeted terrapins (Testudines: Pelomedusidae: Pelomedusa), with descriptions of six new species, Zootaxa 3795 (5), pp. 523-548 : 540

Pelomedusa somalica sp. nov.

Diagnosis: Small to medium-sized, light-coloured helmeted terrapins with a known maximum straight carapacial length of 15.7 cm. Pectoral scutes triangular to rectangular with wide or, rarely, narrow midseam contact. One large undivided temporal scale on each side of head. Two small barbels under chin. In adults, plastron completely yellow; soft parts ventrally lighter than dorsally. Pelomedusa somalica differs from all other Pelomedusa species by the presence of thymine (T) instead of adenine (A), cytosine (C) or a gap at position 122 of the 360-bp-long reference alignment of the 12S rRNA gene (Supporting Information).

Holotype: The Natural History Museum , London ( BMNH 1970.1481 , field number 502, adult, Borama district , Awdal, Somaliland / Somalia, N9°55 E43°10, 4500 ft; coll. R.H. R. Taylor, 17 December 1932; Fig. 5 top).

Description of the holotype: Shell. Straight carapacial length 15.7 cm, plastral length 13.7 cm. Pectoral scutes rectangular with very wide midseam contact. Carapace light chestnut; plastron entirely yellow.

Paratypes: The Natural History Museum , London ( BMNH 1931.7.20.412–414, juvenile and two shells of adults with heads in alcohol, Buran , Sanaag, Somaliland / Somalia; BMNH 1931.8 .1.177, juvenile, Ceerigaabo , Sanaag, Somaliland / Somalia); Naturhistorisches Museum Wien ( NMW 24449, juvenile, Abyssinia) .

Derivatio nominis: The species name somalica refers to the geographical origin of the new species.

Distribution: Somaliland, Somalia ( Vargas-Ramírez et al. 2010; Wong et al. 2010; Fritz et al. 2014). A genetically verified paratype of P. somalica (NMW 24449) was collected in Abyssinia by Baron Carlo von Erlanger (5 September 1872 – 4 September 1904) in 1901. Abyssinia comprised present-day Eritrea and northern Ethiopia, suggesting that P. somalica also occurs in one or both of these countries.

Remarks: Pelomedusa somalica corresponds to mtDNA lineage VI of Vargas-Ramírez et al. (2010). Our phylogenetic analyses of mtDNA sequences indicate that P. somalica is part of the northern species group of Pelomedusa and that P. barbata from the Arabian Peninsula is its sister species. However, the relatively deep divergences among Somali terrapins from two sites being only 40 km distant ( Vargas-Ramírez et al. 2010; Table S1 ) raise the possibility that P. somalica consists of more than only one species. This situation warrants further research. That more than one species could be involved is also suggested by two morphologically divergent specimens from Somaliland in the Museum für Naturkunde, Berlin (ZMB 27266, 49719). These relatively small adult males of 13.0 cm and 10.9 cm straight carapacial length differ from the type series from Awdal and Sanaag regions (Somaliland) significantly in their distinctly darker colouration. Without genetic verification, we are reluctant to identify them with P. somalica and exclude them explicitly from the type series.

Figures

FIGURE 5. Dorsal and ventral aspects of the holotype of Pelomedusa somalica sp. nov. (BMNH 1970.1481, adult, Borama district, Awdal, Somaliland/Somalia; top) and of Pelomedusa variabilis sp. nov. (SMF 58075, subadult male, Gold Coast, Ghana; bottom). Scale bars, 3 cm. Photos: A. Petzold and E. Morawa.