Psammophylax ocellatus Bocage, 1873

Branch, William R., Baptista, Ninda, Keates, Chad & Edwards, Shelley, 2019, Rediscovery, taxonomic status, and phylogenetic relationships of two rare and endemic snakes (Serpentes: Psammophiinae) from the southwestern Angolan plateau, Zootaxa 4590 (3), pp. 342-366 : 356-357

Psammophylax ocellatus Bocage, 1873

Angolan Skaapsteker

Psammophylax ocellatus Bocage 1873 , 221. Bocage, J.V.B. 1873. Melanges erpetologiques. II. Sur quelques reptiles et batraciens nouveaux, rares ou peu connus d‘Afrique occidentale. Jorn. Acad. Sci. Lisboa 4: 209–227.

Type locality: “de l’interieur de Mossamedes (Gambos) par M. d’Anchieta“ ( Bocage, 1873). Crawford-Cabral & Mesquitela (1989) updated this to “Chibemba, Huíla Province (15°46'S, 14°06'; 1316 m a.s.l)”, which was refined without comment to “Chibemba, Huíla Province; 15°45'11.18"S, 14°04'31.62"E; 1321 m a.s.l” by Wallach et al. (2014). The use of Chibemba to anchor the ill-defined region of ‘Gambos’ by Crawford-Cabral & Mesquitela (1989) is based on the region “Circunscrição dos Gambos” which in the late nineteenth century was already defined. The village Chibemba developed near a fort, "Forte dos Gambos" on the road between Lubango and Xangongo (L. Veríssimo pers. comm., 3 April 2018).

Holotype: MBL? Presumed lost in fire that destroyed the Lisbon Museum collections. Broadley (1977b) inspected the Bocage material during a visit to the Lisbon museum in 1968 but noted that Bocage’s type was then absent and it is considered lost, although its fate remains unknown.

Synonymy:

Psammophylax ocellatus Bocage 1873, p221 .

Psammophylax rhombeatus Bocage 1895 n, p108.

Trimerorhinus rhombeatus (part) Boulenger 1896, p138.

Psammophylax rhombeatus FitzSimons, 1957, p239 .

Psammophylax rhombeatus ocellatus Broadley 1977, p20 .

Material examined. Psammophylax ocellatus : PEM R17986 , Estação Zootécnica (14°54'35.7"S, 13°17'50.8"E, 2175 m a.s.l), Huíla Province, Angola, 14 January 2009, WR Branch & KA Tolley ; PEM R16270 ( NB561 ), Tundavala rock trap, south of observatory , (14°48'29.8''S, 13°24'3.2”E, 2275 m a.s.l), Huíla Province, Angola, 19 February 2017 ; NB171 , Tundavala dirt road , (14°49'11"S, 13°23'49"E, 2263 m a.s.l), Huíla Province, Angola, 13 April 2016 ; NB491 , Tundavala grassland near rocks, south of observatory (14°48'29.2''S, 13°24'5.2''E, 2275 m a.s.l), 21 November 2016 ; NB492 , Tundavala rock trap, south of observatory (14°48'29"S, 13°24'04"E, 2275 m a.s.l), Huíla Province, Angola, 16 November 2016 ; NB585 , Tundavala grass trap, south of observatory (14°48'37"S, 13°24'13"E, 2286 m a.s.l), Huíla Province, Angola, 21 April 2017 ; NB586 , Tundavala grassland near grass trap, south of observatory (14°48'28.8''S, 13°24'7.2'' E, 2276 m a.s.l), 20 April 2017 (all Tundavala material collected by N. Baptista) . SAM ZR 46424 , Calueque , Cunene Province, Angola (-17.3750S, 14.6250, 1108 m a.s.l), July 1983 (2930—part of John Visser Coll.?) .

Description. The smallest skaapsteker (maximum 875 mm; see Broadley 1977b for other species). Nostril pierced between single pre- and post-nasals; preocular 1, separated from frontal; postoculars 2 (sometimes 3 on one side); temporals usually 2+3 (sometimes 2+2 or 2+4); supralabials 8, the fourth & fifth entering orbit (sometimes 3–4); infralabials 10–12, the first 5 usually in contact with anterior sublinguals (rarely 4–6); dorsal scales in 17-17- 13 rows; ventrals 156–183 (see discussion above); cloacal shield divided; subcaudals 57–68. Tail length 21.5–29.1% of total length (see discussion above). Dorsum grey, heavily patterned with longitudinal series of paravertebral and lateral ocelli; paravertebral ocelli comprise 1–2 central reddish brown scales irregularly encircled in black and then with a thin yellow-orange ring, and separated in the midline by a thin white-yellowish line that runs from the neck to the base of the tail; the lateral ocelli are larger and have 1–3 greyish scales and a narrow black edge. Head uniform brown on top with a narrow elongate extension onto the neck; iris of eye brilliant red; the supra- and infralabials are white with scattered black blotches that form more regular bars on the latter; two large, solid back blotches occur on each side of the head, the largest on the temporal region, the other on the side of the neck; ventrum white with 2–5 subtriangular black spots that arise at the base and extend halfway to the free edge of most ventral scales; subcaudals grey-white with scattered blotches on the lateral edges.

Scalation details of specimen are summarized in Table 2 .

Size: Maximum size: Male (MBL 1724) 720 + 155 = 875 mm

Habitat. Recent material was collected in montane grassland on the edge of the Humpata Plateau, in the vicinity of the Chela Escarpment at an altitude of 2100–2300 m a.s.l, with scattered sandstone outcrops, seepage lines, and patches of Protea sp. bush and dwarf miombo woodland dominated by Brachystegia spiciformis ( Fig. 1C ). The climate, pedology, geomorphology and woody species composition were characterised by Barbosa (1970) for Angolan montane grasslands in the Humpata and Tundavala regions. The Tundavala collecting sites were dominated by the grasses Loudetia simplex, Schizachyrium sanguineum, Diheteropogom filifolius, Hyparrhenia cymbaria and Elionurus muticus . All Tundavala snakes, except for NB171, were collected within close proximity (0.1 km 2) and around 1 km from the edge of the plateau in the south of the Tundavala SASSCAL biodiversity observatory in habitat consisting of montane grasslands on sandy soil and with weathered sandstone outcrops.

Distribution. Currently restricted to isolated populations, with recent material inhabiting montane grasslands at the edge of the Humpata Plateau in the vicinity of the Chela Escarpment ( Fig. 6 ). It represents a range extension of about 122 km to the northwest from historical material from the Main Plateau region of Huíla and Cunene provinces. It also more than doubles the altitudinal range of the species (1108 m to 2286 m a.s.l). The presence of another putatively isolated population in the Angolan section of the Cuvelai-Etosha Basin from Calueque requires confirmation.

Ecology. NB586 and NB491 were collected while active during the day. PEM R17986 was collected during the day under a small slab within 30 cm of the edge of a small stream. It had an adult Tomopterna cf. tuberculosa in its stomach, that was mainly undigested and probably collected during the previous night. This was the most frequently seen species of snake in the scope of the Tundavala monitoring events, indicating that it is locally common.

Figures

FIGURE 1. Psammophylax ocellatus PEM R17986, Estação Zootécnica, montane grasslands, Huíla Province. A: dorsum showing the characteristic boldly blotched body, a thin vertebral line separating the paravertebral ocelli, and the absence of a dark nape collar; B: ventrum showing the white belly with irregular rows of dark spots, that are absent below the tail; C: Live specimen showing general colouration and striking red eye; D: Habitat—montane grasslands, Estação Zootécnica, Huíla Province, Angola. All photos by W. R. Branch.

FIGURE 6. Distribution of Psammophylax ocellatus (green) and Psammophis ansorgii (blue). Right (A): Africa with location of Angola in blue. Middle (B): Topographic map of Angola, showing relief and central localities, and red square outlining the location of the Humpata Plateau, adjacent to the Chela Escarpment. Localities: 1–2 Catchiungo—Chinguar (blue star) type locality of Psammophis ansorgii; 3, Cunhangamua; 4, Tundavala; 5, Estação Zootécnica; 6, Chibemba (green star) type locality of Psammophylax ocellatus; 7, Humbe; 8, Calueque, near Ruacaná. Left (C): zoomed in region of Humpata Plateau.