Koch's Barking Gecko, named after Dr. C. Koch who collected the first specimen and reported the unusual gecko calls from Gobabeb. There, at the type locality for this species, mainly through his energy and devotion, the Namib Desert Research Station has been erected, which made further studies and collections possible.
TYPES : Holotype: Adult male, TM 28809, coll. by W. D. Haacke, October 1963. Allotype: Adult female, TM 28447, coll. by W. D. Haacke, May 1963.
Paratypes: TM 24993 — 4, coll. by C. Koch, Oct. 1957. 25880 — 1, 25883 — 4, 25887, 25889 — 90, p5947, coll. by C. K. Brain, May 1959. 28442 — 6. 28448 — 55, 28625 — 7, coll. by W. D. Haacke, Oct. 1963.
The data from three specimens not from the type locality have been included in the statistical analysis.
TM 25885, 25888, coll. by C. K. Brain, Rooibank, May 1959. 28388, coll. by W. D. Haacke, Farm Greylingshof, dist. Swakopmund, May 1963.
All types are in the Transvaal Museum, Pretoria.
DIAGNOSIS: A stoutly built ground gecko, similar in general appearance to the common Barking Gecko (Ptenopus garrulus), but usually bigger than specimens of the latter from the same localities. Body scales much smaller than the scales of other species of the genus, and consequently a greater number of scales round the middle of the body, viz. 187—222. Toes and fingers fringed laterally with elongate pointed scales. Yellow colour in males not restricted to the throat only, but extending over labials on to sides of snout, neck and body.
DESCRIPTION: Holotype: Adult male, TM 28809, total length 119.8 (61.8 + 58) mm, tail length 93.8% of snout-vent length. Body covered with minute flattened scales, numbering 220 round middle of body, 82 gulars below eyes, 57 scales between supracilliary ridges. Upper labials 8, lower 9. Nostril pierced between 2 nasal scales, which are distinctly swollen. Nostril capable of being closed from the inside by a projection from upper nasal; nasal separated above rostral by a single, enlarged granule. Ear opening a short oblique slit. Rostral and mental undivided; cheeks swollen; no enlarged gular scales.
Toes and fingers flattened and fringed laterally greatly elongated, pointed scales. Tail tapering covered with small, subimbricate scales. Three enlarged tubercular scales on either side of base of tail; postanal sacks present; preanal and femoral pores absent. Peritoneal lining pigmented.
Colour in life: Basic dorsal colour reddish brown, with dark brown infusions, which are darker laterally. Underside of body, limbs and tail white. Throat sulphur-yellow. Yellow colour not restricted to throat but spreads over labials on to sides of snout, and also in the form of irregular spots along sides of neck and body. Hands paler in colour than body, dark infusions on toes and distal half of tail form indistinct crossbars. Supracilliary ridges a pale reddish brown. Iris brown, with lighter areas on dorsal and ventral edges of pupil, and marked with fine wavy lines.
Allotype:Adult, total length 104.6 (62.8+41.8) mm, body/tail ratio smallest in series. Base of tail not swollen, two enlarged tubercles on either side. 207 scales round middle of body, 84 gulars, 57 interorbital scales, 10 upper labials, 10 and 11 lower labials, nostrils surrounded by 2 nasal scales each.
COLOUR (in alcohol): Underside, throat and lateral spots white, otherwise similar to holotype.
Paratypes: In general scale character of paratypes similar to holotype, but colour varies to a certain extent from very light to darker specimens.
Statistically the most significant difference between P. kochiand the other two species is the much higher scale count round the middle of the body. No practical overlap was observed nor is a theoretical overlap of ± 3 S.D. possible. Further-more P. kochi has a higher mean HB/tail ratio, which is not, however, very significant as overlaps were observed.
In P. kochi an internal projection of the upper nasal scale can close the nostril, in P. garrulus this isnot always so well developed, while in P. carpi the nostrils are open.
Males of all species have yellow throats. In P.kochi the yellow colour spreads to other parts of the body, while in the other species only a very restricted area is covered on the throat itself. It was generally assumed that the females of all the Ptenopus spp. had white throats, but, in October 1963, all three females of P. carpi had yellow throats, although the actual areas covered were smaller than in the males. The females might be more subject to seasonal changes, as Brain did not observe this fact when collecting the type-series in May 1959. Attention should also be given to this possibility in the other species.
The toes of all three species are fringed laterally with elongated, pointed scales which, however, are weaker developed in P. carpi than in the other two species. The fingers too are fringed laterally with elongated, pointed scales in P. kochibut with triangular more or less pointed scales only in P. garrulus and P. carpi.
Peritoneal lining in P.kochi and P.garrulus pigmented, unpigmented in P. carpi.