Pelomedusa olivacea (Schweigger, 1812)

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 : 539

Pelomedusa olivacea (Schweigger, 1812)

1812 Emys olivacea Schweigger —Restricted type locality: Senegal; holotype: Muséum National d’Histoire naturelle, Paris, MNHN 7971

1884 Pelomedusa gasconi Rochebrune —Restriced type locality (by neotype designation, Fritz et al. 2014): Dagana, Senegal; neotype ( Fritz et al. 2014): Zoologisches Forschungsmuseum Alexander Koenig, Bonn, ZFMK 17076 (Fig. 6 bottom in Fritz et al. 2014)

Diagnosis: Small to medium-sized helmeted terrapins with a known maximum straight carapacial length of 16.8 cm. Pectoral scutes triangular and either just meeting at their tips along the plastral midseam or more or less widely separated. One large undivided temporal scale on each side of head. Two small barbels under chin. Carapace and plastron light coloured. Soft parts dorsally darker than ventrally. Pelomedusa olivacea differs from all other Pelomedusa species by the presence of guanine (G) instead of adenine (A) or cytosine (C) at position 123 and by the presence of adenine (A) instead of guanine (G) at position 271 of the 360-bp-long reference alignment of the 12S rRNA gene (Supporting Information).

Distribution: Genetically verified records for P. olivacea are known from Benin, Burkina Faso, Niger, Nigeria, and Senegal ( Vargas-Ramírez et al. 2010; Wong et al. 2010; Fritz et al. 2014).

Remarks: Pelomedusa olivacea corresponds to mtDNA lineage III of Vargas-Ramírez et al. (2010). Phylogenetically, P. olivacea belongs to the northern clade of Pelomedusa and is most closely related to P. variabilis from Ghana and the Ivory Coast ( Fig. 1 ). In both species, the pectoral scutes may be triangular with or without midseam contact. Among 21 museum specimens of P. olivacea , 18 have completely divided pectoral scutes and three have triangular pectoral scutes just meeting at the plastral midline. This matches the description for Senegalese P. olivacea given in Rochebrune (1884).

The monogenean flatworm Polystomoides nabedei Kulo, 1980 was described from helmeted terrapins from Siborototi, Togo (most likely Pelomedusa olivacea or P. variabilis ). This parasite was described as a distinct species based on morphological differences from Polystomoides chabaudi , which is known from Pelomedusa subrufa and probably P. neumanni (see respective species accounts).

Figures

FIGURE 1. Maximum Likelihood tree for helmeted terrapins (Pelomedusa spp.) using 1848 bp of mitochondrial DNA (12S, cyt b, ND4+tRNAs), rooted with Pelusios sinuatus. Terminal clades collapsed to cartoons. The topology of the Bayesian 50% majority rule consensus tree was identical. Numbers along branches indicate bootstrap support and clade support under BI (posterior probabilities) greater than 50 or 0.95, respectively. Asterisks represent maximum support under both methods. Colours and symbol correspond to the map (Fig. 2). On the right, proposed species names indicated; in brackets, mtDNA lineages. For clade membership of individual samples, see Table S1. The questionable sample MTD T 5484 from Swellendam District (Western Cape), South Africa, is highlighted in red (see text). The shown terrapins are Pelomedusa neumanni (top; Kakamega, Kenya) and P. galeata (bottom; Port Elizabeth, South Africa—photos: H. Prokop and W.R. Branch).