Tomopterna branchi, Wilson & Channing, 2019

Wilson, Lyle & Channing, Alan, 2019, A new sand frog from Namaqualand, South Africa (Pyxicephalidae: Tomopterna), Zootaxa 4609 (2), pp. 225-246 : 232-240

Tomopterna branchi sp. nov.

Namaqua Sand Frog

Figs. 4 , 5 .

Holotype. A male, ZMB 87233, field number AC3383 ( Fig. 4 ), collected in the dry bed of the Buffels River where it is crossed by the N7 highway, Namaqualand, South Africa, 8 May 2015, by N. Telford ( WGS84 : 29.67791°S, 17.05214°E).

Paratypes. ZMB 87234, a female from Kamieskroon, and ZMB 87235 a male from Springbok .

Diagnosis. The new species has been confused with Tomopterna delalandii , and is similar to all other species of sand frogs in morphology and burrowing behaviour. It has an advertisement call of a rapidly-repeated series of high-pitched notes, the most common type of call in sand frogs. We assign it to the genus Tomopterna based on the presence of teeth on the maxilla, the inner metatarsal tubercle strongly flanged, the outer metatarsals bound into the sole, and the presence of vomerine teeth, all characters that distinguish the genus Tomopterna ( Poynton 1964) .

The following comparisons are based largely on data in Wasonga & Channing (2013). The new species has single subarticular tubercles, distinguishing it from those with divided tubercles: T. gallmanni , T. krugerensis and T. wambensis . It has more than three phalanges of the fourth toe free of web, distinguishing it from those with more webbing: T. elegans , T. gallmanni , T. luganga , T, marmorata , T. tandyi and T. wambensis . There is a row of isolated glands below the tympanum, distinguishing it from those species with a distinct continuous or interrupted ridge: T. cryptotis , T. damarensis , T. elegans , T. gallmanni , T. kachowskii , T. krugerensis , T. luganga , T. natalensis , T. tandyi , T. tuberculosa and T. wambensis . The outer metatarsal tubercle is absent or present as a small white bump, which distinguishes it from those species with prominent outer metatarsal tubercles: T. delalandii , T. elegans , T. kachowskii , and T. tandyi . There is a transverse dark interocular bar present, which distinguishes it from those species without this pattern element: T. damarensis , T. luganga and T. natalensis . This bar is variable in T. elegans , T. kachowskii , and T. tandyi . The back is smooth or has small warts, distinguishing it from T. gallmanni and T. tuberculosa , which have prominent dorsal tubercles.

The advertisement call consists of a rapidly-repeated series of high-pitched notes, distinguishing it from the knocking call of T. krugerensis and T. gallmanni . The first two harmonics are emphasised (933–995 Hz; 1866–1990 Hz) at a note repetition rate of 3 s-1. Tomopterna natalensis also has two emphasised harmonics, but at higher frequencies (1272–1488 Hz; 2544–2976 Hz). It is further distinguished from those species with only a single harmonic emphasised, at a higher frequency ( T. wambensis , T. tandyi , T. damarensis , T. sp. 3 and T. cryptotis ), and T. luganga and T. marmorata with a single emphasised harmonic at a lower frequency. The call of Tomopterna delalandii has the second harmonic emphasised, at a similar frequency to T. branchi , but the note repetition rate is approximately twice that of T. branchi . The call of T. elegans is unknown.

The new species may occur with T. delalandii and T. tandyi . It can be distinguished from T. delalandii which has a distinct ridge below the tympanum (isolated glands), a prominent outer metatarsal tubercle (weak or absent), and an advertisement call with a note repetition rate of about 6 s-1 (about 3 s-1). It differs from T. tandyi which has more than three phalanges of the fourth toe free of webbing (three free), a ridge below the tympanum (isolated glands), a prominent outer metatarsal tubercle (weak or absent), and an advertisement call with a single harmonic emphasised at 1.9–2.1 kHz (two harmonics emphasised).

The uncorrected p -distances (as percentages) of T. branchi compared to all other species of sand frogs based on 16S rRNA vary from 2.3–6.0%. The uncorrected p -distances between T. branchi and T. delalandii are 2.2–3.4% for 16S ( Table 2 ) and 2.5–4.3% for tyrosinase exon 1.

......continued on the next page ......continued on the next page Description of holotype. A male ( Figs. 4 , 5 ) SVL 42.4; the body is robust; head short (HL/SVL 0.37, HW/SVL 0.44), not wider than trunk, not longer than wide (HL/HW 0.83); snout short (SL/HL 0.44), rounded in dorsal view, truncated in profile, slightly projecting beyond lower jaw, narrow (SL/IND 1.97); canthus rostralis rounded; loreal region slightly concave; nostrils situated on slight projections, closer to the eye than snout tip (ENL/SNL 0.86); eyes directed anterolaterally, slightly protruding, relatively small (ED/HL 0.40); eye diameter less than snout length (ED/SL 0.91); interorbital distance is less than upper eyelid (IOS/ELD 0.46), and nearly equal to internarial distance (IOS/INS 0.94); Internarial distance just more than half eye diameter (IOS/ED 0.56); vomerine teeth inconspicuous; tympanum visible, smaller than eye diameter (TD/ED 0.46); a row of isolated glands below tympanum; upper jaw without dentition; choanae small, round, vomerine teeth absent; tongue notched posteriorly, 7.0 at widest part; median lingual processes present; vocal sac single, darkly pigmented anteriorly; dorsal surfaces of head, trunk and limbs generally smooth; ventral surface of limbs, gular and abdomen smooth. Arms slender; hand moderately large (HND/SVL 0.26); tips of fingers not enlarged into discs; relative length of fingers: IV <II <I <III; subarticular tubercles single and distinct, with one on fingers I, II and IV, and two on finger III; fingers without webbing; thenar tubercle distinct; metacarpals with supernumerary tubercles; pale nuptial pads present on upper surface of fingers I and II.

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Hind limbs stout, tarsal tubercle absent, represented by a small raised area; tibia short (TL/SVL 0.40); heels not reaching each other when knees are flexed and thighs are held at right angle to body; foot shorter than tibia (TL/ FOT 0.84); relative length of toes: I<II<V<III<IV; toes without expanded discs; subarticular tubercles: one on toe I and II, two on toe III, three on toe IV and two on toe V; pedal webbing formula I 1– 2 II 1– 2 III 1– 3 IV 3.5– 2 V; thin margin of webbing extending to tips; inner metatarsal tubercle prominent and shovel-shaped, continuing as a tarsal ridge, smaller than eye diameter (IMT/ED 0.63); outer metatarsal tubercle present as a small white bump. Measurements of the holotype and paratypes are presented in Table 3 .

Colour in life. The dorsal pattern of the holotype consists of green patches with black warts on a reddish-brown background ( Fig. 4 ). The transverse bar between the eyes is green with black flecks. The iris is pale golden with dark veins. Small pale tubercles are densely scattered over the back and sides. The flanks have irregular brown and white marbling. The upper surfaces of the limbs are brown, with green or darker brown transverse bars. The venter is white with a black throat. Colour in preservative. The pattern is clearly visible ( Fig. 5 ) as a darker brown on a paler brown background.

Paratype variation. The male from Nababeep ZMB 87234 ( SVL 43.1 ) and the female from Kamieskroon ZMB 87235 ( SVL 43.6 ) have similar morphology to the holotype, and practically identical body proportions. A male from Springbok (no voucher) had pale dorsolateral stripes and a thin vertebral stripe. In life, it had a greybrown background with black and brown warts, and a pale occipital patch.

Advertisement call. Calls were recorded at the town dam in Springbok, 28 January 1985, air temperature 22°C. No voucher was collected. The call consists of a number of rapidly repeated notes, which have the first two harmonics emphasised 933–997 Hz and 1866–1990 Hz. The note repetition rate is 3 s-1. In contrast, the call of T. delalandii from Elands Bay (air temp 14° C) shows a much faster note repetition rate, and has only one frequency, the first harmonic, emphasised ( Fig. 6 ).

Eggs and tadpoles. Eggs are unknown. Tadpoles were found in shallow pools in the riverbed 23 October 2012 and in a small cup-sized depression against a rock in the otherwise dry sandy bed of the Buffels River, 7 May 2015. The tadpoles are practically identical in proportions and pigmentation to those of Tomopterna cryptotis illustrated by Channing et al. (2012). A brief description of AC3247 from the Buffels River is given here. Gosner stage 36, TL 31.8; oral disc 0.8 width of head at level of disc; a single row of marginal papillae present; anterior and posterior jaw sheaths 80% pigmented; LTRF 4(2–4)/3(1); nostrils elliptical; internarial ratio NW/ID 0.25; orbitonasal line not visible; pineal spot a small white dot; extra-ocular proportion (HWE-EO)/EO 0.64; spiracle situated 0.6 along body; opening constricted, visible laterally; vent ratio TUB/VW 2.8; height of caudal muscles at base of tail/height of trunk 0.66; small brown spots around eyes to nostril and snout tip, then over the dorsal surface of the body where it is most dense; sides and top of tail muscle lightly marbled; ventral fin unpigmented, dorsal fin transparent with some fine black lines and blotches.

Distribution and habitat. The species is presently known from the Buffels River drainage of Namaqualand ( Fig. 7 ), but may be more widely distributed once further investigations have been undertaken. This area includes the Namaqualand Hardeveld vegetation units of the Succulent Karoo Biome ( Mucina et al. 2006). A photo of the type locality is shown in Fig. 8 . Tadpoles occupy shallow pools together with tadpoles of Amietia poyntoni .

Etymology. The specific epithet refers to Dr W.R (Bill) Branch (1946–2018), who passed away while this paper was being prepared. We suggest that the English common name, Namaqua Sand Frog, be used.

Figures

FIGURE 4. Photo of the live holotype (ZMB 87233) of Tomopterna branchi, from the Buffels River, Namaqualand, South Africa. Photo: A. Channing.

FIGURE 5. Dorsal, ventral and lateral views of the holotype of Tomopterna branchi ZMB 87233.

FIGURE 6. Sound spectrogram of Tomopterna branchi (22°C) from Springbok (left) showing two frequencies emphasised (notes indicated by horizontal lines), and T. delalandii (14°C) from Elands Bay (right) showing the second harmonic emphasised. No vouchers were collected.

FIGURE 7. Localities where Tomopterna branchi has been collected or observed (green squares). Buffels River drainage shown in blue, N7 National Road shown as a broken red line.

FIGURE 8. The type locality (in the dry season) of Tomopterna branchi.