Ptenopus australis, Becker & Alexander & Tolley, 2025

Becker, François S., Alexander, Graham J. & Tolley, Krystal A., 2025, Singing on key: An integrative taxonomic revision of barking geckos (Gekkonidae: Ptenopus) with six additional species and keys for morphology and advertisement calls, Vertebrate Zoology 75, pp. 277-323 : 277-323

Ptenopus australis sp. nov.

Figures 9 , 10 , 20 B

Common names.

Southern barking gecko

Afrikaans: Suiderlike blafgeitjie

Chresonymy.

Ptenopus garrulus maculatus – Oelofsen and Vorster (1976), Rebelo et al. (2018)

Comment.

Specimens of this species have not yet been included in any taxonomic revision of this genus, only in two publications on range extensions of ‘ P. g. maculatus ’. These records were further notably included in the range maps of ‘ P. g. maculatus ’ by Branch (1998), and of ‘ P. garrulus ’ by Bates et al. (2014), Telford et al. (2022), and Tolley et al. (2023).

Holotype.

PEM R 23122 , adult male, collected from farm Rooidraai , Eastern Cape Province, South Africa (–32.4645, 23.6330, 860 m a. s. l.) by Werner Conradie, Alexander Rebelo, and Philip Jordaan, on 2 November 2017.

Paratypes.

PEM R 23118 –23121, adult males except for PEM R 23120 (allotype), collected from farm Doringkraal , Eastern Cape, South Africa (-33.0479, 24.9611, 305 m a. s. l.), by Werner Conradie, Alexander Rebelo, and Philip Jordaan, on 31 October 2017 .

Additional material examined.

See Table S 1 for additional unvouchered photographed specimen (1), and call recordings (4) examined (total n = 5 excluding types).

Etymology.

This is the most southern Ptenopus species, occurring near the southernmost tip of Africa. Therefore, we use the specific epithet “> australis ”, the Latin (masculine) adjective meaning “ southern ”.

Diagnosis.

The smallest Ptenopus (SVL max. 44.6 mm, mean 42.7 mm, n = 5) with the shortest tail of any Ptenopus species (TL 61 % of SVL, only one specimen had full original tail, but other paratypes / holotype lost a very small portion of the tail tip and they still appear to be similarly short) and a moderately stout appearance. It is distinguished from P. kochi , P. carpi , and P. sceletus sp. nov. by: Being substantially smaller; toes being intermediately fringed laterally (vs. weakly fringed in P. carpi and P. sceletus sp. nov. and extensively fringed in P. kochi ), with fringe length being at least half the breadth of the toe between fringes (vs. generally less than half in P. carpi and P. sceletus sp. nov., and generally equal to in P. kochi ); ventral surface being generally white or cream with some unpigmented and / or dark brown-speckled scales on the (hand / foot) soles (vs. substantial pink, unpigmented patches on the tail and limbs in P. kochi , and immaculate white in P. carpi and P. sceletus sp. nov.); having MBSR 140–156, mean 148 (n = 5) (vs. ≥ 187–222 in P. kochi and usually <135 in P. carpi and P. sceletus sp. nov.); a generally brown-and-cream spotted appearance with some paired light and dark markings dorsally (vs. pinkish or orange, more evenly spotted pattern in P. kochi and banded pattern in P. carpi and P. sceletus sp. nov.). It is further distinct from P. carpi and P. sceletus sp. nov. by the nasals being more swollen and the nostrils partially covered by internal projections of the upper labials; from P. kochi by having fingers laterally fringed with pointed triangular scales (vs. elongated pointed scales in P. kochi ).

From congeners previously included in ‘ P. garrulus ’ it is distinguished by: A smaller internasal scale, with higher IN / INSBB (~ 10.6, range 7.3–11.6, n = 5) and lower INSH / NB (~ 0.65, range 0.57–0.97, n = 5) than P. circumsyrticus sp. nov. (IN / INSBB <6, INSH / NB usually> 0.97); having lower RB / RH (<1) than these congeners (usually> 1, except for some P. adamanteus sp. nov. individuals); having lower MBSR (~ 148, range 147–149, n = 5) than P. garrulus and P. kenkenses sp. nov. (≥ 158); IOS / MBSR (~ 0.26, range 0.24–0.29) usually higher than P. garrulus (~ 0.23, range 0.20–0.25, n = 10); having 3 internasal scales in contact with the rostral (vs. usually <3 for P. garrulus and P. adamanteus sp. nov., ≤ 2 for P. kenkenses sp. nov. and P. maculatus , and only 1 in P. circumsyrticus sp. nov.).

Holotype description.

(Fig. 11 ). Adult male, SVL 44.63 mm with original tail short with blunt tip, 21.99 mm (49.3 % of SVL). Body and head covered with minute hexagonal to round scales of a similar size, dorsally and ventrally, with scales on limbs slightly larger. Mid-ventral incision, T-shaped, for removal of liver sample. Body stout, MBSR 149, IOS 43, HL 13.48 mm, HW 8.33 mm, HH 5.68 mm, EED 3.87 mm. Upper labials 7, lower enlarged labials 7; nine granules bordering the mental. Clear but not prominent superciliary ridges tapering above mid-eye level; right eyelid partially depressed by the fixing process with skin folds on the forehead. Prenasal scales slightly swollen, separated by three small, asymmetrical internasal scales in contact with the rostral, with IN / INSBB 17.14, INSH / NB 0.65; nostrils almost entirely covered by projection from the upper nasal. Rostral is large, with RB / RH 0.96; mental deep and slightly pointed ventrally. EYE 2.58 mm, pupil vertical; ear opening is oblique (~ 40 °), and narrow with small, slightly projecting scales at the anterior margin. Toes elongate, slightly flattened, with elongate fringed scales; small, pointed, barely projecting triangular fringes on the fingers; strong, recurved and pointed nails on fingers and toes.

Colouration.

In life, the paratype PEM R 23121 (Fig. 10 A – B ) has a dorsal background colour light brown with cream and dark brown asymmetrical blotches and a few orange spots or blotches (holotype appears to have been similar, but darker with finer patterning); light and dark dorsal markings merge into poorly defined ‘ bands’ on the tail hat become more defined distally; dark brown blotches extend onto lateral surfaces with slight, dark grey markings below the lateral line on the white (similar to holotype); ventrum is immaculate white except for the slight dark grey mottling laterally, which is more visible on the head and tail; slight dark speckling and some unpigmented or punkish scales on hand palm, while foot sole is densely pigmented with dark speckles. Clear, bright yellow gular patch; the bright yellow does not extend onto the lateral surfaces of the head, body, or onto the limbs. Iris is light silver.

In preservative (Fig. 9 ), the lighter colours have faded to off-white or beige, the darker colours remain various shades of dark brown or grey, while the orange and yellow have faded completely (on paratype PEM R 23121 and presumably on the holotype and others). The eyes turned a milky blue-grey.

Variation.

See Table S 1 for paratype and additional material measurements and scale counts, which does not vary substantially among the types. Colour pattern varies relatively little among specimens, with darker or lighter, finer or courser colour patterns being visible. Males have bright yellow gular patches, and may have slight yellow infusions on the legs and face (Fig. 10 C ).

Advertisement call.

The advertisement call (Figs 3 , 20 B ) consists of 5.8 notes (range 5–6) uttered in rapid succession, with a note rate of 6.68s - 1 (range 5.10–7.54). Note duration is short, 21 ms (range 21–22), and highly regular, with note 1 duration deviance 6 % (range 1–19 %). Inter-note intervals are short (117 ms, range 107–169 ms) and regular, although the last interval can be slightly longer; inter-note interval range 29 % (range 13–55 %). Call density moderately low (0.18, range 0.17–0.20). Call duration shortest of all species, only 0.82s. The basal frequency was inestimable within our sample set, with the dominant frequency at 4.4 kHz (range 4.2–4.5 kHz); a very slight lower peak frequency band may present around 1.3 kHz. Frequency appears to remain constant throughout the short note. The (human) perceived pitch tends to be higher than that of most other species. Bandwidth (90 %) is difficult to estimate consistently with the recordings available.

During peak chorus activity, this species appears to call much more frequently than most other species (although sample size is small), the call period being a very short 9 seconds. The typical period of calling activity in a day is not known, but the analysed calls (during full chorus) were recorded 20–40 minutes after sunset.

Habitat and distribution.

This species occurs on open Karoo scrub plains with sandy or gravelly substrate ( Rebelo et al. 2018), usually near small dune hummocks, south of the Great Escarpment in the Western Cape of South Africa (essentially the southern Nama Karoo). It has not been recorded in sympatry with any other species.

Natural history.

Very little is known about the natural history of this species, although it is assumed to be similar in many aspects to congeners, particularly to the sister species, P. garrulus , which also occurs in a similar climatic setting. So far, calls have only been recorded during late October, during the austral spring (recordings in this manuscript; Rebelo et al. 2018). The breeding period is expected to last for at least 2–3 months, as in the closely related P. garrulus and P. adamanteus sp. nov. As in several other species, they call from their burrow entrances in exposed or partially concealed locations ( Rebelo et al. 2018).

Figures

Figure 3. Box and whisker plots of the bioacoustic characters analysed using ANOVA / Kruskal-Wallis tests, for species of Ptenopus. Numbered characters (numbered as in Methods) and their units are indicated on y-axis labels. Species colours correspond to those on Figure 2 and indicated on the key. Significant differences (according to pairwise post hoc tests) are indicated through homogenous groupings: Species not significantly different in the present character are one group, as indicated by lower-case letters. Species that share the same letters not differing significantly from each other; species with multiple letters are not significantly different from any other species sharing those letters. Approximate divisions between the groups are indicated by dotted lines perpendicular to the y-axis, and the group letters are indicated to the right of each graph.

Figure 9. Holotype (PEM R 23122) of Ptenopus australis sp. nov. from Rooidraai, Eastern Cape Province, South Africa (– 32.4645, 23.6330). Scale bar = 1 cm. Photos by Werner Conradie.

Figure 10. Life colour variation in Ptenopus australis sp. nov.: A, B PEM R 23121 from farm Doringkraal, Western Cape Province, South Africa (– 32.3355, 22.2053), photos by Alexander Rebelo; C iNaturalist record 58938339 from NE of Beaufort West, Western Cape Province, South Africa (– 32.2087, 22.7614), photo by Courtney Hundermark.

Figure 11. Holotype (NMNW R 11390) of Ptenopus adamanteus sp. nov. from Grosse Bucht Bay, || Karas Region, Namibia (– 26.7338, 15.1041). Scale bar = 1 cm relative to full ventral and dorsal views. Photos by Francois S. Becker.

Figure 20. Sonograms (top graphs) and oscillograms (bottom graphs) of representative advertisement calls of Ptenopus species (A – J, species names indicated on graphs). Both x and y axes are directly comparable / equally scaled across species. Specimen numbers and localities: A NMNW R 11585, NE of Koës, Hardap Region, Namibia; B iNaturalist 140169978 (Jacobus Retief), Merweville, Western Cape Province, South Africa; C NMNW R 11622, E of Lüderitz, || Karas Region, Namibia; D NMNW R 11643, SW of Gobabeb, Erongo Region, Namibia; E NMNW R 11657, NE of Keetmanshoop, || Karas Region, Namibia; F NMNW R 11704, Gobabeb; G NMNW R 11716, Hoanib River, Kunene Region, Namibia; H NMNW R 12114, Gobabeb; I NMNW R 11843, NW of Gobabeb; J NMNW R 11790, N of Swakopmund, Erongo Region, Namibia. The audio files on which this figure is based, are made available (File S 2).