Ptenopus kochi Haacke, 1964

Ptenopus kochi Haacke, 1964 View in CoL

Figures 6 View Figure 6 , 20 I View Figure 20

Common names.

Koch’s barking gecko

Afrikaans: Duin blafgeitjie

Chresonymy.

Ptenopus garrulus maculatus (in part) – FitzSimons (1943: 13)

Ptenopus garrulus (in part) – Brain (1962)

Ptenopus kochi Haacke, 1964: 1 View in CoL , pls. I – V, Haacke (1969: fig. 3 a), Haacke (1975: 227)

Comment.

A description of the morphology of this species is not revised here. An updated diagnosis, some natural history observations, and a formalised bioacoustic call description, are provided.

Holotype.

TM 28809 , adult male, collected from “ Gobabeb , South West Africa [ Namibia], central Namib Desert ( – 23°37’South, 15°03’East, 408 m) ”, by Wulf D. Haacke in October 1963. GoogleMaps

Paratypes.

TM 24993 –4, collected by Charles Koch in October 1957 GoogleMaps ; TM 25880 –1, 25887, 25889–90, collected by Charles K. Brain in May 1959 GoogleMaps ; TM 28442 –6, 28448–55, 28625–7, collected by Wulf D. Haacke in October 1963 GoogleMaps . Locality: same as holotype.

Material examined.

See Table S 1 for vouchered (1) and unvouchered photographed (16) specimens, DNA samples (16 available, 7 sequenced), and call recordings (20) included (total n = 34).

Diagnosis.

The largest Ptenopus ( SVL max. 65.1, mean 61.1, n = 23) with the longest tail ( TL 83 % [range 63–96 %] of SVL, n = 23), an overall plump appearance, extensive toe fringes and elongated fringed scales on the fingers compared to other species. It is distinguished from all other congeners by a combination of the following characters: Body and head scales finer than other species, with MBSR 187–210 (vs. generally <200 for P. garrulus and <180 for other species); dorsal colour pattern (Fig. 6 View Figure 6 ) finely speckled with a few somewhat enlarged cream or yellow spots (somewhat similar to P. garrulus , vs. banded in P. carpi and P. sceletus sp. nov. and large paired, oval marking in P. maculatus , P. circumsyrticus sp. nov., P. kenkenses sp. nov., and northern populations of P. adamanteus sp. nov.); the tail, fore- and hind-foot soles are completely or partially pink and unpigmented, whereas the rest of the ventrum is white (similar to P. garrulus except for the tail, vs. immaculate white in P. maculatus , P. adamanteus sp. nov., P. circumsyrticus sp. nov., and black- or dark grey-speckled in P. kenkenses sp. nov.); the yellow pigment in males is not limited to the throat, but extends over the sides of the snout, head, neck, and body (also the case in some P. garrulus ). For a more detailed morphological description, see Haacke (1964, 1975).

Colouration.

In life (Fig. 6 View Figure 6 ), colouration varies from bright to dull orange with yellow (especially in males) or whitish spots covering the dorsum, and differing degrees of dark brown spots or reticulations sometimes being present. The tail is spotted or lightly reticulated to somewhat barred dorsally, with a yellow or whitish tip.

Ventrally, animals are immaculate white with pinkish patches on the limbs, soles, and tail. Males have brilliant yellow throats, the colour extending across the entire ventral and dorso-ventral surface of the head and often along the lateral surfaces of the body and legs.

In preservative, the dorsal colours eventually fade to beige, brown, and grey. The brighter colours, especially yellow, eventually fade completely.

Advertisement call.

(Figs 3 View Figure 3 , 20 H View Figure 20 ) Consists of 13 notes (range 11–19) uttered in rapid succession with a note rate of 7.90s - 1 (range 5.98–10.33). Note duration is short (27 ms [range 18–40]) and relatively regular, sometimes slightly shorter as the call progresses, with note 1 duration deviance low (20 % [range 6–31]). The inter-note intervals are usually short (98 ms [range 75–130]) and regular with inter-note interval range low (30 % [range 14–52]). Median call density is high (0.28 [range 0.20–0.34]) and call duration long ( 1.6s [range 1.2–2.4]). The basal frequency is 382 Hz (range 301–492) but very soft and may be inestimable, with harmonic bands louder towards the upper dominant frequencies, the upper at 3.3 kHz (range 3.1–3.88) and a clear lower dominant frequency around 1.4 (range 1.1–1.9) kHz, about half the upper dominant frequency. Frequency appears to remain constant throughout the notes and call, as is the case with the (human) perceived pitch. Bandwidth (90 %) is difficult to estimate consistently: approximately 0.7–4.9 kHz.

This species calls more intensively and for a shorter period of time than its sympatric or parapatric congeners ( P. carpi , P. maculatus and P. circumsyrticus sp. nov.). Calling also commences earlier in the day than these congeners. Call period (mean 74 s) varies greatly, but can be as low as 9 seconds during peak chorus activity. Calling activity is crepuscular, commencing shortly before or at sunset, and ending at nightfall. Sporadic calls may occasionally be heard later at night, in the morning, or on overcast days ( Haacke 1969).

Distribution and habitat.

Occurs throughout the Namib erg in the central Namib Desert, Namibia, except possibly in the southwestern extreme of this erg in the winter rainfall zone, near Lüderitz. The northern limit of its distribution is generally aligned with the northern extent of the sand sea.

The habitat of this species was initially described as the silts in Kuiseb River and the interdune plains by ( Haacke 1964), and was even referred to afterwards as the “ interdune barking gecko ” ( Branch 1998). In reality, this species rarely occurs on the interdunes and its occurrence in and around the Kuiseb River is more coincidental with sandy intrusions from the adjacent Namib erg. Its primary habitat is characterised by the dune plinth, being the base of the dune where the sand is loose, but before it slopes more steeply. “ Dune plinth barking gecko ” would thus be a more suitable substitute common name. Its occurrence on the interdunes is only peripheral, except in instances where the interdunes sand is very loose, similar in composition to a typical dune plinth. True interdune plains in the Namib erg are occupied primarily, or solely, by P. circumsyrticus sp. nov.

Ptenopus kochi occurs parapatrically alongside P. circumsyrticus sp. nov. throughout the Namib erg, and in occasional sympatry or occasional syntopy. It also occurs parapatrically with P. carpi and P. maculatus along the Kuiseb River. Some P. kochi do occur on the northern banks of the Kuiseb River, occasionally in sympatry with P. maculatus and P. circumsyrticus sp. nov., on sandier patches of the gravel plains. These animals are genetically divergent from those on the southern side of the river.

Natural history.

Breeding generally occurs from September to December ( Polakow 1997), but this species may occasionally call throughout much of a year following above-average rainfall. Rainy weather may cause calling activity to cease for days to weeks.

It has previously been characterised as being nocturnal ( Haacke 1969), but is more crepuscular. This species is more frequently observed on the surface during the day (e. g., Murray and Lease 2015) than congeners, except perhaps for P. circumsyrticus sp. nov.

Courtship appears to be more complex than in other species, and also more variable. Some courtship encounters witnessed by FB were similar to that of P. maculatus , with the female simply approaching the calling male and the male responding with a few calls. The female then scratches rapidly at the burrow entrance to indicate she wants to enter, after which the male retreats backwards and the female follows him inside. In other encounters, the males may exit the burrow and display their gular patch to the approaching female. Yet more variations, including mutual head bobbing and soft vocalisations, have been observed ( Polakow 1997). In some cases, the female may inspect the burrow of a potential suitor, entering through one opening and leaving through another soon after, if she (presumably) finds the burrow unsuitable ( Polakow 1997). Mating takes place within the burrow, with the male usually uttering something similar to the advertisement call from within the burrow, after a female has entered.

Fighting is common among closely-spaced males. In one observation (FB), a young male charged a much larger calling male at its burrow entrance, from several metres away. The two animals stood belly-to-belly on their back legs, rapidly clawing one-another with their hands for one or two seconds, before the younger male retreated. Scars from bite-marks on the body are commonly observed in both sexes, but more often in males.

The burrows of P. kochi tend to be more complex than other species, often with more than one entrance ( Polakow 1997; FB observations). Males, females, and hatchlings share burrows for extended periods of time, and a male and female will generally use separate entrances to the same burrow system. See Polakow (1997) and Haacke (1964, 1978) for additional notes on P. kochi courtship and ecology.