Pachydactylus vanzyli (STEYN & HAACKE 1966)
Female of Pachydactylus vanzyli.
© J. Boone.
Male of Pachydactylus vanzyli.
© J. Boone.
Male of Pachydactylus vanzyli.
© F. Colacicco.
Hatchling of Pachydactylus vanzyli.
© J. Boone.
Habitat of Pachydactylus vanzyli.
© M. Barts.
Originalbeschreibung / Original description
Type material: Nineteen specimens.
Holotype: Male CR 4000/7. Allotype: Female CR 4000/8. Paratypes: CR 4000/1 — 6 and CR 4000/9—19.
Other material: Eleven specimens: CR 4063, collected about 30 miles inland from CapeFrio (indicated as CapeFria on some maps) along the track to Orupembe by P. Motonane.
CR 4048/1 — 5 collected at the type site by 13. van Zyl and W. Steyn in the eve ning of the 13th and dug up in the early morning before sunrise on the 14th No vember, 1965.
CR 4064/1 and 5, collected about 33 miles SSE of Cape Frio in the inter-dune spaces among loose barchans near a granitic hill on the eastern border of the subcoastal dune field, by W. Steyn, 15th November, 1965 (Fig. 4).
CR 4064/2, 3 and 4 collected on the barren vegetationless gravel terraces (Fig. 5 and 6) east of the Khumib river, 10 miles upstream from Sarusas West, by W. Steyn on the 16th November, 1965. The last-mentioned eleven specimens are in the collection of the StateMuseum in Windhoek.
Diagnosis: A nocturnal ground gekko, superficially resembling both Palmatogecko rangei Andersson and Colopus wahlbergii Peters, hut differing from both in having a combination of pedal characteristics as described in the generic diagnosis given above.
Description: Holotype: CR 4000/7, adult male, total length 93.4 (54.4+39) mm. Head slightly flattened, about 1½ times as long as broad; temporal area swollen; snout obtu sely pointed, In length being about 1.0 times the horizontal diameter of the eye; distance from eye to ear 1.3 times the diameter of the eye; ear opening small, oval and oblique, in length about 1/3 the horizontal diameter of the eye; latter large, orbit slightly bulging, pupil a vertical, lobed slit of Gekko-type (acc. Un derwood 1954) which can close down to four pinholes due to the overlapping of the marginal lobes. Nostril pierced between three nasal scales, which are slightly bulging and are separated behind rostral by a single, enlarged internasal; the lateral nasal scale has an interior projection (Plate 5). Rostral slightly broader than deep; upper labials 9-10; lower labials 10-11, decreasing in size be hind; mental narrow, about twice as long as broad, projecting beyond the adjoin ing lower labials and slightly tapering and rounded behind; one enlarged, rounded chin shield on either side of mental and in contact with first lower lab ial; throat covered with minute, juxtaposed granules, which pass to flattened, rounded to subhexagonal, imbricate scales on the throat and belly and are largest preanally. Preanal and femoral pores absent. Granules on snout slightly larger than on back of head; head, neck and back covered with small, subequal, smooth, rounded and juxtaposed granules. Scales on tail larger than on belly, squarish in shape and in more or less regular, transverse rows above and below. Tail Unsegmented, tapering to a fine point, which is slightly compressed laterally. Base of tail with two strongly enlarged, oviform swellings and a row of four large, pointed, upward-curved scales on either side. Postanal sacs present. Limbs normal and overlapping when adpressed, covered with rounded, juxtaposed granules which pass gradually to flattened, imbricate scales distally and on feet. Fingers slightly webbed at the base, but free and tapering towards the distal joint which is again slightly wider and covered by a nail-like scute. Sides of fingers and interdigi tal membrane and underside of mantis covered by sharply pointed, closely fitting granules (Plate 2), giving the edge a serrated appearance. No claws visible (Re tracted?).
Fingers terminate below in two transverse adhesive lamellae, of which the distal one is slightly wider and is divided into two by a median longitudinal groove (Plates 1 and 2). A single, large, transversely enlarged, wedgeshaped, callous scale, bordered distally and proximally by a similar, but smaller scale, occurs on the second phalange from the tip of the three middle fingers but is less well developed on finger 1 and practically absent on finger 5 (Plates 1, 2, 3). Toes 1 to 4 webbed up to the terminal joint, fifth slender and free. Sides and undersides of toes and interdigital lamellae and underside of feet covered by spinose, close fitting tubercies, which give the edges a serrated appearance (Plate 4). Terminal phalange below ending in two transverse, adhesive lamellae, of which the distal one is divided into two by a median, longitudinal groove, while above an enlarged nail-like scute overlies the small, retractile claw. The adhesive lamellae on the toes, in particular toe five, are narrower and not as well developed as those of the fingers.
Colour: Basic dorsal colour light brown; parietal area and sides of head, sides and underside of limbs and a row of 5 large subcircular to subhexagonal blotches on the back and 5 on the tail, purplish-pink. The blotches on the back and tail are bordered by more or less confluent rows of dark brown to black specks. Sim ilar specks are irregularly scattered in the brown areas of the back of the head, neck, body, limbs and tail. A brown median line consisting of specks runs back from between the eyes to the occipital region, where it splits into two branches, each of which curves over the temporal area, to reach forward to just behind the eye. Snout brownish, supraorbital area bluish, due to the black eyeballs showing through the semi-transparent skin; extrabrillar fringes light yellow above and in front of the eye, but white below and behind; belly and underside of tail white, and a number of white spots on the sides of the body, on the limbs and feet.
Allotype: CR 4000/8, adult female, total length 106.9 (63.5+43.4)mm. In gen eral appearance similar to holotype male, but differing as follows: Postanal swellings absent and the row of four enlarged scales on either side of base of tail flattened and not as well developed as in male; 9—9 upper labials; 7—9 lower labials; no enlarged chin shields present. Claws visible on first fingers of both hands. Colour pattern as in holotype but blotches more clearly defined.
Paratypes: In general similar to the holo- and allotype, but individual variation occurs as follows:
Upper labials:— 9—11; 5 (9), 21 (10), 12 (11).
Lower labials:—7—12; 1 (7), 1 (8), 6(9), 5 (10), 19 (11), 6(12).
As the lower labials decrease in size posteriorly and eventually are indistinguish able from the adjoining scales, it is difficult in most cases to give an exact count.
In all specimens, except CR 4000/13 and CR 4000/14, in which the nasorostrals are in contact, there is a single internasal scale behind the rostral, separating the nasorostrals. Enlarged chin shields are present in the holotype and three other males. The claws on fingers were only observed on two fingers of the allo type. As the claws are retracted and therefore invisible on some toes in a num ber of specimens, it is assumed that the fingers of all specimens are also clawed. The number of enlarged scales on either side of the base of the tail varies from 3 to 5 (usually 4), and differ in size between the sexes as described in the holo and allotype.
The two prominent swellings at the base of the tail in male specimens, Into which the hemipenes are retracted, make the sexes very easy to distinguish.
Of the nineteen specimens in this series five males, but only one female, have regenerated tails.
The colour varies only slightly amongst specimens/individuals from the type locality but markedly so amongst individuals from different sites. Basic dorsal colour more pinkish in specimens (Figs. 2 and 3) from the type site in con trast to a distinct brown in specimens (Figs. 6 and 7) from other localities.
The number of lighter coloured blotches on the back varies from 4 to 7 and are in some casesmore or lessconfluent forming a vertebral band (Fig. 7). On the original tails there are about 5 such blotches which are more elongated transversely than those on the back, Regenerated tails arc irregularly speckled.
Size: Largest complete specimen:— CR 4000/10 (female), 109.1 (63.7 + 45.4) mm.
Largest specimen and largest female:— CR 4000/4, HB 65.5 mm., tail re generated.
Largest complete male:— CR 4000/7 (Holotype), 93.4 (54.4 + 39) mm.
Largest male:— CR 4000/13, IIB 57.8 mm., tail regenerated.
Field notes: The specimens of the type series were collected in hilly terrain in the period from shortly after sunset to about 11 p.m. The temperatures and relative humid ity during these periods were as follows
|
4th Oct., 1965 |
7.20 p.m. |
21° C |
45% |
|
|
11.00 p.m. |
131/2°C |
83% |
|
5th Oct., 1965 |
6.00 p.m. |
21° C |
45% |
|
|
10.45 p.m. |
14° C |
78% |
The hills consisted of rocky outcrops of schistose, metamorphic rocks and volcan ic intrusions with slight accumulations of red Kalahari type sand amongst them. The vegetation consists of scattered, low, stunted bushes, shrubs and euphor bia with a sparse cover of Aristida grass. Some of these gekkos were collect ed on the sand, usually freezing at the approach of the light, or in some cases trying to escape by running quite fast, while others were found sitting on stones.
One captured specimen climbed up the smooth sides of a tin can. The stomach contents of one specimen consisted of the remains of termites and a single phasmidlike reduviid bug.
On the second expedition after Mr. van Zyl pointed out the site (Fig. 9) where Mrs. van Zyl first found this gekko in the early morning, it became evi dent that Kaokogecko vanzyli is really an inhabitant of the coarsely sandy, gray el and grit-covered plains which form the inter-dune spaces in this area but which extend considerably beyond the dunefields.
The camouflage effects of this gekko’s colour and colour pattern against this kind of surface are evident in Figures 6 and 7. At the suggestion of Mr. van Zyl it was attempted to observe the gekko in the hours before dawn on the 14th of November, 1965, at the type site. In contrast however to another site only a few miles off, none were seen, but shortly before sunrise some tracks were found leading into a hole.
The hole resembled that of Palmatogecko in shape, but was located in the valley away from the sandy accumulations. Two specimens of Kaokogecko vanzyli were promptly dug out of such holes from a depth of between 15 and 20 cm. Numerous efforts to dig out these gekkos during the day time failed. It would appear that the holes became closed either by the gekko, or by the gritty earth collap sing latcr in the day. The holes occurred among numerous rodent holes at the type site. On the second expedition the senior author saw a specimen of Kaoko gecko vanzyli piercing the blocked entrance of a hole from below, emerging in a miniature cloud of dust. This happened shortly after sunset at the locality near Sarusas (Fig. 5). This hole was marked and the photograph shown in Figure 6 was taken the next day.
Some specimens of Palmatogccko rangei and of Kaokogecko vanzyli were kept alive during the second expedition. It was noticed every morning while in the fog belt, that both genera started digging as soon as the fog started lifting. During this period it happened usually towards 9 a.m., temperature around 20°C. It is as sumed at the moment that light and or temperature or humIdity are stimuli Con tributing to this digging activity. From observations made of captive specimens it appears that Kaokogecko digs more slowly and more powerfully than Palmato gecko. Their digging activities show a basic difference: although excavating is done with the forelimbs, and debris removed with the hindlimbs in both genera, the waste removal is different. The webbed feet of Kaokogecko actively clasp and pick up the excavated material, depositing it further to the rear, while in Palmatogecko the webbed rear feet merely push the debris along the surface. The different surfaces to which the two genera are adapted would account for these behavioural differences. The much coarser material with particles of great ly differing sizes into which Kaokogecko digs — in contrast to the smooth, hom ogeneous dune sand in the case of Palmatogecko poses more digging prob lems. Kaokogecko vanzyli and Palmatogecko rangei were collected within yards of each other at two further sites during the second trip. These sites are shown in Figures 4 and 5.
Furthermore at the type site of Kaokogecko vanzyli, a spider Leucorchestris porti Lawrence was dug up from a hole in a valley where there are no dunes. Likewise at a locality 30 miles east of Cape Frio a new species of Sparassid spider (Lawrence 1966) was found in a locality away from the dune fields, but where Kaokogecko vanzyli is also present.
At the Rhumib river site, Kaokogecko vanzyli was found together with Palmatogecko rangei, Typhlacontias bogerti Laurent and Ptenopus carpi Brain.
At this latter site the different habitat of Palmatogecko and of Kaokogecko were strikingly demonstrated when, shortly after sunset, Kaokogecko individuals began emerge from holes in the gravel plain, while Palmatogecko individuals emerged only a few yards off, within the same light circle thrown by a pressure Lantern, from holes located in patches of coarse sand against the slope.