Ptenopus adamanteus, Becker & Alexander & Tolley, 2025

Ptenopus adamanteus sp. nov.

Figures 11 View Figure 11 , 12 View Figure 12 , 20 C – D View Figure 20

Common names.

Diamond coast barking gecko

Afrikaans: Diamantkus blafgeitjie

Chresonymy.

Ptenopus garrulus maculatus View in CoL (in part) – FitzSimons (1935: 525; Haalenberg, Luderitzbuch, Soebartsfontein); FitzSimons (1937 b: 160; Port Nolloth, Kamaggas), Haacke (1969: 92; Annisfontein, Daberas, Sendelingsdrif, Swartpoort), Mertens (1971: 44; southwestern localities), Haacke (1975; southwestern localities)

Ptenopus garrulus (in part) – Brain (1962: fig. 3; southwestern localities)

Comment.

All coastal and near-coastal specimens in the southern Namib Desert ( Namibia) and Richtersveld ( South Africa) previously referred to as ‘ P. g. maculatus ’, are presently assignable to this species. It appears to not occur sympatrically with any other species, except potentially with P. kenkenses sp. nov. on the eastern margins of its range. Northern and southern populations of this species display several notable differences, including body-size. However, phylogenetic evidence presently suggests that these populations may form a gradual cline, rather than being two distinct species.

Holotype.

NMNW R 11390 , adult male, collected from Grosse Bucht , south of Lüderitz, || Karas Region, Namibia ( –26.73379, 15.10412, 29 m a. s. l.), by Francois S. Becker and Bertha Buiswalelo on 27 September 2022. GoogleMaps

Paratypes.

NMNW R 11391 –3 ( two adult males and one adult female NMNW R 11391 = allotype), same collection details as the holotype GoogleMaps ; NMNW R 11350 , subadult female, collected from the pump house along main road, Sperrgebiet , || Karas Region, Namibia ( -26.9932, 15.3584), by Dayne Braine on 10 September 2021 GoogleMaps .

Additional material examined.

See Table S 1 for unvouchered photographed specimens (21), DNA samples (17 available, 7 sequenced), and call recordings (8) included (total n = 28 excluding types).

Etymology.

This species is named in reference to the diamond-scattered coastline that forms its habitat, including the Sperrgebiet in Namibia and the Richtersveld in South Africa, where extensive diamond mining occurred historically and continues to this day. We use the specific epithet “ adamanteus ”, the Latin adjective meaning “ of diamond ”, framed in the male genitive to match the gender of Ptenopus .

Diagnosis.

Southern populations of this member of the genus have a small body size ( SVL max. 45.1 mm, mean 39.4 mm, n = 19) with long tails ( TL 77 %, range 60–99 %, n = 19) while that of the northern populations is moderate (up to 50.8 mm, mean 49.7 mm, n = 6), with a moderately long tail ( TL 71 %, range 67–76 %, of SVL) and an overall lean appearance. It is distinguished from P. kochi , P. carpi , and P. sceletus sp. nov. by: 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., generally equal to in P. kochi ); having MBSR 141–185 (vs. ≤ 131 in P. carpi and P. sceletus sp. nov. and> 185 in P. kochi ); by having on the dorsum 4–5 paired, more-or-less symmetrical, light-coloured, ovoid markings on the body, about half the diameter of the eye or larger, interspaced by dark brown blotches (vs. more finely patterned dots 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 ), and having white pigmented ventral scales on entire ventral surface (vs. pink, unpigmented patches on the tail and limbs in P. kochi ).

From congeners previously included in ‘ P. garrulus ’ it is distinguished by: Having immaculate white pigmented scales on soles, vs. some pink, unpigmented scales on soles of P. garrulus and P. australis sp. nov., and dark speckling on the soles of P. kenkenses sp. nov. and P. australis sp. nov.; having a usually smaller internasal scale than P. circumsyrticus sp. nov., with IN / INSBB ~ 8 (usually> 6.0, vs. usually <6.0 in P. circumsyrticus sp. nov.); higher RB / RH (~ 1.1, usually ≥ 1 and <1.2) than P. australis sp. nov. (usually ≤ 1.0), but lower than P. circumsyrticus sp. nov. (usually> 1.1); usually lower INSH / NB (usually <1.1) than P. circumsyrticus sp. nov. (usually> 1.1); having a generally higher IOS (mean 45, range 35–53, n = 30) and IOS / MBSR (mean 0.29, usually> 0.24) than P. maculatus ( IOS usually <37, IOS / MBSR usually <0.24); having one or two inernasal scales in contact with the rostral vs. three in P. australis sp. nov.

Holotype description.

(Fig. 11 View Figure 11 ). Adult male, SVL 49.94 mm with original tail 35.20 mm (70.5 % of SVL). Body and head covered with minute hexagonal to round scales of a similar size, dorsally and ventrally, with scales on limbs notably larger. Small mid-ventral incision for removal of liver sample. Body slender, MBSR 170, IOS 53, HL 15.87 mm, HW 11.19 mm, HH 6.68 mm, EED 5.89 mm. Upper labials 8, lower enlarged labials 8 with an additional small, elongate scale on the inflection of the jaw; eight granules bordering the mental. Clear but not prominent superciliary ridges tapering above mid-eye level; a single row of elongated scales around the anterior and upper margins of the eye with curved tips posteriorly, the scales being smaller and rounder along the posterior and dorsal edges. Prenasal scales swollen, separated by one small, asymmetrical hexagonal internasal scale in contact with the rostral, with IN / INSBB 6.90, INSH / NB 0.50; nostrils partially covered by projection from the upper nasal. Rostral is narrow and tall, with RB / RH 0.76, MB / RB 0.89. Eyes intermediate, EYE 3.46 mm, pupil vertical; ear opening is oblique (~ 45 °), and narrow with small, slightly projecting scales at the anterior margin. Toes elongate, flattened, with elongate fringed scales, small, pointed, triangular fringes on the fingers; strong nails on fingers and toes, being larger and thicker on the fingers.

Colouration.

In life, the holotype (Fig. 12 A View Figure 12 ) has a dorsal background colour of dull orange or light brown with light grey-purple, cream, and grey spots; four pairs of large, cream / white, ovoid markings on the back interspaced by diffuse, mottled, dark brown-purple patches; these markings coalesce into alternating cream and light purple / brownish bars on the tail (9 dark bars, the last two very faint). Laterally the colours and markings fade, with immaculate white ventrum. Laterally, the body has five white circular markings, dorsally outlined with light brown / purple. Yellow gular patch extensive, with additional yellow spots on the snout, laterally on the head, body and neck, and on anterior surfaces of the back legs. The iris is a light green-grey or greenish camel.

In preservative (Fig. 12 View Figure 12 ), the lighter colours faded to off-white or beige and the darker colours to shades of dark brown or grey, while the immaculate white areas appear more cream. The yellow has faded completely and the iris is milky blue-grey.

Variation.

Refer to Table S 1 and Figure 4 View Figure 4 for range of morphometric characters, including the paratypes. Internasal scale is typically small and asymmetrical; rostral typically narrow and tall; toe fringes relatively extensive. Dorsal colouration highly variable, matching the wide variation of substrate colours and surface textures across its range. Northern populations (Fig. 12 A – D View Figure 12 ) have a similar colour pattern to the holotype, whereas the southern populations (Fig. 12 E – H View Figure 12 ) have a more finely speckled or dotted appearance somewhat similar to P. garrulus . The northern populations occur more often on deflation plains with pebbles or course sand on the surface (despite finer sand beneath the surface), whereas the southern populations tend to occur in fine sandy substrates – which may account for the colour pattern difference (this appears to be the pattern across the genus). Observed colour variations include overall cream, greyish, ochre, or even brick red background colouration with speckling colour variations including brown, white, olive, purple, orange, and black. Ventrally, animals are immaculate white, although some southern populations possess black or dark grey speckling on the throat and lateral edges of the body, occasionally intruding onto the belly. Males have bright yellow gular patches which often extend onto the lateral head and body, and yellow on anterior surfaces of the hind leg.

Advertisement call.

The advertisement call (Figs 3 View Figure 3 , 20 C View Figure 20 ) consists of 5 notes (range 4–6), uttered slowly at a rate of 2.81s - 1 (range 2.64–3.15). Note duration is short (29 ms [range 24–34]) and highly consistent; note 1 duration deviance 9.2 % (range - 4–16). Inter-note intervals 313 ms (range 274–341), with a notably longer final interval; inter-note interval range high, 52.2 % (range 36–66). Median call density is low, 0.09 (range 0.08–0.11); call duration 1.4s (range 1.1–1.8). The basal frequency is ~ 415 Hz (range 370–516, but very soft and may be inestimable, with harmonic bands louder towards the (upper) dominant frequency at 4.4 kHz (range 4.1–5); usually no notable lower peak frequency peak is evident. Frequency appears to remain more or less constant throughout the note, and (human) perceived pitch is notably lower in northern than southern populations, and also coastal compared to inland populations. Bandwidth (90 %) is difficult to estimate consistently: approximately 0.5–7.3 kHz.

In coastal populations this species does not call often (longer call periods and fewer evenings of calling), but inland populations are more vocal. This is probably due to higher incidence of cold, foggy, windy weather closer to the coast, in which calling activity is reduced. Call period (5–20 s, mean 14 s) is short compared to most other species during peak chorus activity. It mainly calls from about 30 minutes before sunset until nightfall, with occasional calling later at night. This species may call sporadically throughout the day, particularly under foggy or cloudy conditions.

Habitat and distribution.

(Fig. 5 View Figure 5 ). This species occurs on small coastal dunes, sandy plains, and on deflation plains in the southern Namib Desert, or the Namaqualand-Richtersveld steppe ecoregion (see Dinerstein et al. 2017). It occurs from the edge of the intertidal zone, inland to about 50–80 km from the coast. The habitat falls within the coastal fog zone and receives rain predominantly in the austral winter.

Natural history.

While its breeding phenology is not well known, our sampling suggests that calling / breeding peak activity occurs from September to November, like several other species. This species often wanders on the surface throughout the night, far from its burrow, and may be active despite cold, foggy weather, similar to P. carpi and P. sceletus sp. nov. The burrows are relatively complex with multiple side-tunnels, and a few egg clutches, usually two eggs but occasionally one, have been found inside burrows occupied by a female. This species occasionally closes the burrow entrance from the inside before daybreak, but may also be active diurnally, especially after or during foggy weather. Hatchlings have been observed digging their own burrows a day after hatching, and it is therefore expected that they do not remain in the parent burrows for any length of time. Males and females have not been observed sharing a burrow. This species has been observed feeding on spiders and termites, and it likely eats various arthropods.