Nucras aff. broadleyi

Bauer, Aaron M., Murdoch, Matthew & Childers, Jackie L., 2020, A reevaluation of records of Sandveld lizards, Nucras Gray, 1838 (Squamata: Lacertidae), from northern Namibia, Amphibian & Reptile Conservation (e 271) 14 (3), pp. 231-250 : 245

Nucras aff. broadleyi . CAS 214642 , from 48 km west of Kamanjab on the road to Torra Bay (-19.65389,

14.35083), in the Kunene Region, Namibia ( Fig. 5 ), was strongly supported as the sister to the twoAngolan samples sequenced and identified as Nucras broadleyi by Branch et al. (2019a). There was a 15.03–15.69% divergence in the 16S sequence between the Angolan and Namibian specimens, compared to a 7.83% divergence between the two Angolan samples. While these divergences are relatively high, they are likely artificially inflated because of ambiguities in base calls and alignment in part of the sequences obtained. When compared with the diagnostic features proposed for N. broadleyi , our specimen is consistent with respect to scale characters, most notably the presence of granules between the supraoculars and supraciliaries, the well-defined occipital scale separating the parietals posteriorly, and the absence of a distinct parietal window in the interparietal scale ( Fig. 6C ). It is also consistent in size (58.2 mm SVL vs. a maximum of 63 mm) and falls within the range of all standard but non-diagnostic features of scalation presented by Branch et al. (2019a) for N. broadleyi . However, the specimen differs significantly in color pattern. Branch et al. (2019a) describe the diagnostic dorsal pattern as having a series of longitudinal pale stripes, including four pale stripes on the nape with the lateralmost of these forming a light stripe that is continuous with the outer edges of the parietals. In contrast, the Namibian specimen has a pattern entirely lacking solid longitudinal stripes and instead exhibits pale spots or dashes anteriorly and a series of irregular transverse bars posteriorly ( Figs. 6–7 ). This most closely resembles the pattern seen in adult specimens of N. intertexta , which was, indeed, the field identification given to the specimen by the senior author. However, Namibian N. intertexta are much larger (up to 91 mm SVL) and have a larger number of dorsal midbody scale rows (40–56 vs. 38–48 in Angolan N. broadleyi and 38 in CAS 214642) and usually have the parietals in contact posteriorly (comparative data from Broadley 1972 and Branch et al. 2019a). The mismatch in color is noteworthy, however, both N. intertexta and N. broadleyi show significant variation in their patterns ( Branch et al. 2019a: Fig. 6 ; Broadley 1972: Pl. III), with elements of the pattern of N. intertexta present even in a paratype of N. broadleyi (PEM R24157, Branch et al. 2019a). The recognition of speciesspecific patterns has confounded Nucras systematics since the time of Boulenger (1917, 1920). A possible, though purely speculative, interpretation could be that CAS 214642 represents mitochondrial introgression of N. broadleyi into N. intertexta in northern Namibia. Nuclear data for the Namibian sample would be needed to test this hypothesis. Alternatively, it might represent a new species allied to N. broadleyi or it could be conspecific with Angolan N. broadleyi . Under the last interpretation one would have to assume both that color pattern is very highly variable and that more (and more complete) sequence data would likely reveal less pronounced genetic distances between samples. If conspecific, this would represent a substantial range extension southward and would expand the extent of occurrence of N. broadleyi to over 117,000 km 2. Based on the present evidence, given that we have only a single Namibian sample and very limited DNA sequence data, we refer this single sample to N. aff. broadleyi .

Figures

Fig. 5. Map of Namibia showing the distribution of Nucras damarana (green circles) and N. cf. broadleyi (blue triangle). Black borders indicate regional boundaries. Regions mentioned in the text are: KU – Kunene, OH – Ohangwena, OM – Omasati, OS – Oshana, OK – Oshikoto, and OT – Otjozondjupa. Map courtesy of Edward L. Stanley.

Fig. 6. Nucras aff. broadleyi (CAS 214642). (A) Whole body dorsum, (B) lateral view of head, and (C) dorsal view of head. Note the patterning resembling Nucras intertexta and the prominent occipital scale. Photos by M. Murdoch.