Breviceps branchi, Channing, 2012

Channing, Alan, 2012, A new species of Rain Frog from Namaqualand, South Africa (Anura: Brevicipitidae: Breviceps), Zootaxa 3381 (1), pp. 62-68 : 63-65

Breviceps branchi sp. nov.

Branch's rain frog

Figs. 1 & 3

Holotype. A male, ZMB 77781, field number AC 3053 ( Fig 1 ), collected at the gate to the diamond security area 600 m west of the Holgat River bridge that carries traffic from Port Nolloth to Alexander Bay in Namaqualand , South Africa, 16 October 2008, 28°55'58.4" S; 16°46'08.9" E. For comparison a specimen of Breviceps namaquensis is included in Figure 1 . The type locality is shown in Figure 2 .

Diagnosis. A brevicipitid frog, placed in the genus Breviceps as it does not have squared terminal discs on the phalanges as Callulina ; nor a red V on the head and strong transverse ridges posteriorly on the palate as Splaeophryne; nor strongly granular skin and a downturned vent as Probreviceps ( Channing & Howell 2006) . The latter three genera are restricted to montane forests on the eastern side of the continent, while Breviceps is widespread and common in arid areas in the western parts of the continent.

The new species most closely resembles Breviceps namaquensis in form and colour pattern, from which it cannot be distinguished on differences in body proportions, such as the ratios of HW/ SUL, F/ SUL, and EE/HW. Based on the description of the type series of Breviceps namaquensis ( Power 1926) , the following differences are apparent ( B. namaquensis values in parentheses): Interorbital space 40% of upper eyelid (50%), fourth finger 50% length of second (60–80%), double subarticular tubercles under third and fourth toes (single conical tubercles), soles of feet granulated (smooth), inner metatarsal tubercle well developed, 20 degrees to axis of fourth toe (not well developed, 30–50 degrees), body with even granulations (smooth at least anteriorly), four spots mid-dorsally (two spots), elongated patch on either side of vertebral line in sacral region (spot on either side).

B. branchi sp. nov. is further distinguished from B. namaquensis by the many small granules under the fourth toe (23) compared to the 4–9 of B. namaquensis . The third finger is also more granulated, with 24 small tubercles under the third finger, but no more than 10 in B. namaquensis ( Fig. 3 ). The dark band under the eye extends back to the arm insertion, but does not reach the arm in most B. namaquensis . I examined all the specimens of B. namaquensis in South African institutions (see material listed below), and found that this species never has such granular digits. The granular fingers and toes separate this species from B. acutirostris , B. adspersus , B. bagginsi , B. fichus , B. fuscus , B. gibbosus , B. macrops , B. montanus , B. mossambicus , B. rosei , B. sopranus , B. sylvestris and B. verrucosus when compared to the illustrations in Du Preez & Carruthers (2009) and Channing & Minter (2004).

The 16S mt rRNA fragment differs by 4.5% from B. namaquensis , 5.2% from B. macrops , 8.0% from B. fuscus , and 13% from B. mossambicus . This is within the range of differences between other congeneric species of amphibians ( Fouquet et al. 2007).

Description of the Holotype. A male, snout-urostyle length 41.3 mm. Top of head smooth, upper eyelid slightly granular, with six pale tubercles along margin of eyelid. Lower eyelid white with transparent patches and fine dark speckling. Snout protruding and angular in outline, nostrils thin slits with pale patch on the outer rim. Internostril distance 2 mm. Measurements (mm) of the holotype and a summary of the measurement of 14 B. namaquensis (in parentheses) follow: SUL 41.3 (19.5–51.9, mean 37.1); HW 12.1 (8.2–14.6, mean 12.5); NN 2.0 (1.7–2.5, mean 2.1); IO 2.4 (2.1–4.5, mean 3.6); EL 6.0 (4.8–7.6, mean 6.4); EE 6.6 (4.4–8.5, mean 7.1); IMT 3.8 (1.3–4.7, mean 3.3); FGL 1.9 (0.9–2.8, mean 1.9); T1 5.6 (2.7–7.2, mean 5.2); F 13.8 (7.2–17.5, mean 13.4); H 9.9 (5.5–12.9, mean 10.0); F3T 24 (2–10, mean 6.6).

Fingers well developed, smooth above. Relative finger lengths 3>2>1>4. Fingers with double subarticular and supernumerary tubercles, with 24 tubercles under the third finger ( Fig. 3 ). Palm very granulated. Inner metacarpal tubercle double, rounded, only slightly protruding. Outer metacarpal tubercle flat, divided. Toes well developed, smooth above, but very granulated below. Double subarticular tubercles present on toes 2, 3, and 4. Only the tip of toe 1 extends beyond the fleshy webbing and sole. Fleshy webbing between toes 3 and 4 extends beyond the level of toe 2. Inner metatarsal tubercle elongated, protruding, aligned at 20° to the fourth toe axis. Outer metatarsal tubercle well developed, almost in line with the inner metatarsal tubercle. Throat and ventrum with minute white asperities, and a transparent belly patch. Sides of body with numerous small, white-tipped glands, each with three or more openings. There are 18 of these glands counted along a straight line between arm and leg.

Colour in life. The back is a pale yellow-brown, with darker brown markings. There are paired pale paradorsal patches, with a pale bar from eye to eye over the head. A dark band runs from below the eye to the arm insertion. Numerous small white glandular warts are present on the skin, most conspicuous along the sides ( Fig. 1 ). Colour in preservative. The dark dorsum becomes brown with tan and white markings.

Advertisement call, eggs and oviposition site. Unknown, but breeding behaviour is presumably similar to other species known to deposit eggs in shallow burrows ( Wager 1986, Channing 2001).

Distribution and habitat. The new species is only known from a single specimen, collected near the gate into the diamond area just west of the bridge over the Holgat River. The locality is on red sands, where the vegetation is classified as Northern Richtersveld Yellow Duneveld ( Mucina et al. 2006). This is part of the Succulent Karoo Biome. Details of the geology, vegetation and climate appertaining to the type locality are given by Mucina et al. (2006).

Etymology. The species epithet is a patronym in honour of Dr W.R. (Bill) Branch, herpetologist at the Port Elizabeth Museum (now Bayworld), to mark his formal retirement in May 2011.

Figures

FIGURE 1. A—Holotype of Breviceps branchi sp. nov (ZMB 77781), Photo courtesy K. Wahlberg, B—Breviceps namaquensis from Farm Brasil, Namaqualand, South Africa (ZMB 77780).

FIGURE 2. Map showing the collecting locality (square symbol) of Breviceps branchi sp. nov. AB–Alexander Bay, PN–Port Nolloth, South Africa. Map courtesy Google Earth.

FIGURE 3. Comparison of the tubercles on the hand of A—holotype of Breviceps branchi sp. nov. (ZMB 77781), others all B. namaquensis: B—Silverstroom Strand CDNC 5064, C—Silverstroom Strand CDNC 5099, D—Rocher Pan CDNC Jan 91 female, E— Farm Brasil, (ZMB 77780), F—Rocher Pan CDNC Dec 90 specimen B.