Pyxicephalus beytelli, Preez & Netherlands & and & Channing, 2024

Preez, Louis H du, Netherlands, Edward C, and, Mark-Oliver Rödel & Channing, Alan, 2024, A new bullfrog from southern Africa (Pyxicephalidae, Pyxicephalus Tschudi, 1838), African Journal of Herpetology 73 (1), pp. 61-89 : 73-81

Pyxicephalus beytelli sp. nov. Du Preez, Netherlands, Rödel and Channing

Beytell’ s bullfrog

Figures 6 , 7 , 8

Referred to above as Pyxicephalus aff. adspersus

Zoobank: urn:lsid:zoobank.org:act:15D48E74-594A-46ED-B31A-74F78C94F5C5

Holotype

A male, NMNW R11398 , (field number AL211204F2), collected by L du Preez and EC Netherlands in Khaudum National Park , Namibia (19.0809°S, 20.6966°E), 4 December 2021 ( Figure 6 ).

Paratypes

Four males collected by LdP and ECN in Khaudum National Park , Namibia: SAIAB 141597 ,field number AL211204F1, with the same locality details as the holotype; SAIAB 141598 , field number AL211204H1 and NMNW R11399 , field number AL211204H2 from a muddy pan

(19.0929°S, 20.6201°E); PEM A1359 , field number AL211204A1, from a dirt road (19.3728°S, 20.4999°E) . A male, SAIAB 105031 , field number AACRG 1956, collected by Marleen Byron and LdP from Chief’ s Island, Botswana (19.2108°S, 22.7901°E), 26 November 2009 .

Diagnosis

The new species is similar to all other species of bullfrogs in morphology and burrowing behaviour. We assign it to the genus Pyxicephalus based on the presence of teeth on the maxilla, two large sharp projections on the lower jaw, the inner metatarsal tubercle strongly flanged, no outer metatarsal tubercle, the outer metatarsals bound into the sole, and the presence of vomerine teeth, all characters that distinguish the genus Pyxicephalus from other pyxicephalids ( Poynton 1964).

Pyxicephalus beytelli is a large frog, maximum SVL 208 mm. The large size distinguishes it from P. angusticeps (maximum SVL 78.7 mm), P. edulis (maximum SVL 103 mm) and P. sp 2. (maximum SVL 120 mm). It has strongly developed dorsal skin ridges, differing from the oval dorsal warts of P. angusticeps and P. obbianus . There is speckling between the dorsal mottles separating it from P. angusticeps and P. obbianus which have none. The odontoids are longer than wide, distinguishing it from P. angusticeps and P. obbianus . There is a white spot on the tympanum, distinguishing it from P. adspersus . The tympanum is smaller or equal to the eye, distinguishing it from P. obbianus with a much larger tympanum. The eye-tympanum distance is more than one tympanum width, distinguishing it from P. angusticeps where it is equal to or less than one tympanum, and P. obbianus where the tympanum is adjacent to the eye. There are no cream-coloured lateral stripes or mottles, unlike P. adspersus , P. obbianus , P. edulis and P. sp. 2. The subarticular tubercles on the feet are very small to barely visible, compared to the relatively distinct tubercles in P. adspersus and P. sp. 2.

The colour pattern of a golden yellow back with black markings (see below) is different to the other species.

Pyxicephalus beytelli has a mean HW/ SUL ratio of 0.5, distinguishing it from P. edulis (0.43) and P. angusticeps (0.39). The eye and tympanum are nearly equal in diameter, with a mean ratio of EL/TD of 1.01, distinguishing it from the species with relatively larger eyes, with ratios of 1.47 in P. angusticeps , 1.54 in P. edulis and 1.41 in P. adspersus . The mean ratio ETD/TD is 1.3, distinguishing it from P. angusticeps (0.74) and P. edulis (0.75).

The call is shorter (0.2–0.55 sec) than that of P. adspersus , (0.56–1.79 sec), and longer than that of P. angusticeps (0.08–0.21 sec), with a lower emphasised frequency (172.3– 258.4 Hz) than P. angusticeps (301.5–775.2 Hz). The call is strongly pulsed, unlike all the other species ( Figure 3 ).

The uncorrected p -distances as percentages of P. beytelli compared to all other species of bullfrogs based on 16S rRNA vary from 5.5–10%, and 0.6–1.6% for tyr ( Table 5).

The new species occurs sympatrically with the other large species, P. adspersus in Khaudum National Park in northern Namibia.

Description of holotype (measurements in mm, summarised in Table 6).

A male ( Figure 6A ) SVL 153, SUL 145; the body is robust; head short (HL/SVL 0.36, HW/ SVL 0.47), not wider than trunk, not longer than wide (HL/HW 0.77); snout short (ES/HL 0.46), rounded in dorsal view, bluntly rounded in profile, slightly projecting beyond lower jaw, narrow (ES/IND 2.6); canthus rostralis smoothly rounded; loreal region slightly concave; nostrils situated on slight projections, closer to the eye than snout tip (NOD/NS 0.70); eyes directed anterolaterally, slightly protruding, relatively small (EL/HL 0.19); eye diameter about half of snout length (EL/ES 0.42); anterior interorbital distance is greater than upper eyelid (AIOD/UEL 1.5), and greater than internarial distance (AIOD/IND 2.34); internarial distance subequal to eye diameter (IND/EL 0.9); distance from eye to tympanum nearly twice diameter of tympanum, tympanum slightly larger than eye diameter (TD/ED 1.1); upper jaw with widely spaced recurved teeth ( Figure 7 ); choanae small, round, vocal sac single; dorsal surfaces of head, trunk and limbs with rounded or elongated warts; 10–14 dorsal and lateral longitudinal skin folds that may be continuous or broken, ventral surface of limbs, gular and abdomen smooth.

Front limbs robust ( Figure 6C ), hand moderately large (HAL/SVL 0.21); 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 and II, and two on fingers III and IV; fingers without webbing; thenar tubercle distinct; metacarpals without supernumerary tubercles; pale nuptial pads present on upper surface of fingers I and II.

Hind limbs stout ( Figure 6B ), tarsal tubercle absent; tibia short (TBL/SVL 0.36); heels not reaching each other when knees are flexed and thighs are held at right angle to body; foot equal to tibia; relative length of toes: I <II <V <III <IV; toes without expanded discs; subarticular tubercles very flat to barely visible: 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 1.5–2 III 2–3 IV 3.5–2 V; thin margin of webbing extending to tips; inner metatarsal tubercle prominent and shovel-shaped, continuing as a tarsal ridge, larger than eye diameter (IMTL/EL 1.36); outer metatarsal tubercle absent.

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Colour in life

Dorsal surface golden-yellow to dark orange in groin ( Figure 6A ); dark patches with pale centres roughly in transverse bands over the body; interspersed among the patches a reticulate network of thin black lines. Laterally no black blotches and few black lines. Distinct yellow vertebral line present. Interorbital bar edged in black. Tympanum with a prominent white dot in the centre. Thigh and tibia barred and with scattered transverse black lines. Gular region white with scattered grey blotches. Abdomen white, immaculate.

Colour in preservative

Dorsum dark grey with black blotches and lines. Prominent thin white vertebral line from snout to vent. Gular region with light grey blotching. Tympanum distinctly black with white center. Ventrally smooth, abdomen grey, immaculate.

Paratype variation

Dorsal colour patterns of paratypes vary from asparagus green to yellow backgrounds with silver-blue blotches ( Figure 8 ). All the paratypes have distinct upper jaw barring and a prominent vertebral line with a tympanum as large as the eye. All specimens have a prominent white tympanic patch. A specimen collected in the Okavango was

lime green with dark grey-blue blotches. The SUL range of the paratypes is 108.3– 146.9 mm. No females were collected .

Advertisement call

The advertisement call is brief and distinctly pulsed ( Figure 3 , Tables 2, 4). The call dur-

ation varies 0.2–0.55 sec, with a dominant frequency 172–258 Hz (n = 13). The pulse rate of each note varies 56–88 sec -1. Breeding takes place during the day.

Tadpoles

The tadpoles were described by Channing et al. (2012) as P. edulis from South Luangwa, Zambia.

Habitat and biology

Following a rainfall event, specimens were found at night in shallow water in temporary pans or foraging in savanna woodland and grassland near pans. The type locality is illustrated in Figure 9 . No breeding activity was observed, and no tadpoles were seen. They shared the habitats with Cacosternum boettgeri (Boulenger, 1882) , Kassina senegalensis (Duméril and Bibron, 1841) , Ptychadena mossambica ( Peters, 1854) , P. anchietae (Barboza du Bocage, 1868) , Poyntonophrynus kavangensis (Poynton and Broadley, 1988) and Tomopterna tandyi (Channing and Bogart, 1996) . This species is collected during breeding events and sold along the side of the road, in Namibia and in Angola ( Figure 10 ) (WR Branch pers. comm.).

Distribution

Based on sequence data this species is known from western Botswana, north-eastern Namibia, south-western Zambia and southern Angola. We expect that its range will be found to be much larger, as more data become available. Based on its habitat preference we believe that this species may occur throughout northern and north-western Botswana, northern and north-eastern Namibia, south-western Zambia and we expect the species to be found in south-eastern Angola and north-eastern Zimbabwe. The identity of bullfrogs from this area that have previously been identified as P. adspersus will have to be confirmed using molecular data and we expect many to be P. beytelli .

Etymology

We have the pleasure in naming this species for the late Mr Ben Beytell, Director of Parks and Wildlife Management in Namibia. He was instrumental in the proclamation of the Khaudum National Park, Namibia.

Figures

Figure 3. Sound spectrograms of representative bullfrog calls. (A) Pyxicephalus adspersus (Vetkuil, Limpopo province, South Africa), (B) P. angusticeps (Beira, Mozambique), (C) P. beytelli (Chief’s Island, Botswana), (D) P. edulis (Gorongosa, Mozambique). The black lines indicate the length of each call. Compare frequency of each species’ call in Table 4 in order to identify the calls.

Figure 6. (A) Male Holotype of Pyxicephalus beytelli, NMNW R11398. (B) Right foot. (C) Right hand. Scales both 10 mm.

Figure 7. Pyxicephalus beytelli male. (A) Widely-spaced recurved teeth. (B) Open mouth showing teeth and odontoids.

Figure 8. Colour pattern variation in Pyxicephalus beytelli: (A) male specimen from the Okavango, Botswana; (B) from Khaudum National Park, Namibia (Photos L du Preez).

Figure 9. A-type locality of Pyxicephalus beytelli, Khaudum National Park, Namibia.

Figure 10. Pyxicephalus beytelli being sold along the road in southern Angola (Photo WR Branch).