Phrynomantis newtoni, Ceríaco, Santos, Marques, Bauer & Tiutenko, 2021

Phrynomantis newtoni sp. nov.

( Fig. 7–10 View Figure 7 View Figure 8 View Figure 9 View Figure 10 )

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Phrynomantis bifasciata View in CoL [part]: Boulenger (1882: 173), Bocage (1895: 181, Plate XVIII figure 3).

Phrynomantis bifasciatus View in CoL : Ferreira (1904: 113), Marques et al. (2018: 80), Baptista et al. (2019: 273) View Cited Treatment

Holotype

MHNCUP/ANF-194 (old catalogue number MHNFCUP 127327; Fig. 7 View Figure 7 ), male adult, from Chingo (‒11.2º, 13.85º; 11 m), Kwanza Sul Province, Angola, collected by Francisco Newton around May to July 1903.

Additional specimen

One specimen: BMNH 1873.7 .28.14, unsexed adult without precise locality (“ Angola ”), Angola, collected by Joachim John Monteiro on an unknown date.

Diagnosis

Phrynomantis newtoni sp. nov. has a small, short, blunt head and an elongated, slightly pear-shaped body. Like all members of the genus, it has a smooth, rubber-like dorsal skin. It can be distinguished from other members of the genus by the following combinations of characters: (1) dorsal pattern consisting of large irregular yellowish, red or silver blotches, sometimes arranged in the appearance of an interrupted dorsolateral band; (2) tips of fingers expanded into large disks; (3) ventral coloration mottled with dark markings; (4) throat dark in males.

Description of the holotype

Small ( SVL 41.1 mm), elongated and pear-shaped male specimen, with slender limbs ( Fig. 7 View Figure 7 ); head blunt, wider ( HW 13.5 mm) than long ( HL 10.4 mm); snout projecting beyond upper jaw ( SL 4.5 mm); eyes projecting laterally beyond the eyelids and approximately flush with margins of head in dorsal view; eye not projecting about above dorsal margin of head in lateral view ( UEW 1.6 mm); interorbital distance 1.2 times eye diameter; pupil large and round; loreal region concave; naris small; round, directed dorsolaterally; canthus rostralis short; eye diameter ( ED 3.7 mm) 1.15 times eye-narial distance ( EN 3.2 mm); eye diameter ( ED 3.7 mm) 0.8 times naris to rostral tip; internarial region bumpy; interorbital distance ( IOD 4.3 mm) approximately two times internarial distance ( IND 2.3 mm), tympanum extremely small. Skin of limbs, dorsal and dorsolateral surface of head and body smooth, rubber-like. Skin of venter leathery; skin of gular region smooth.

Limbs ( FLL 11.2 mm; HAL 11.7 mm; TL 12.9 mm; THL 12.9 mm; FL 13.6 mm) and digits well developed but relatively short when compared to the SVL; digits of both manus and pes stout; relative length of fingers: III> II> IV = I; finger tips largely expanded forming disks; fingers with rounded, prominent subarticular tubercles, two palmar tubercles distinct and well separated from one another, one at ventromedial surface of first finger and other at proximal plantar surface, latter being about two times larger than first; webbing between manual digits absent; relative length of toes IV> V = III> II> I; toe tips expanded forming disks; toes with prominent, single subarticular tubercles; webbing between toes absent; prominent inner metatarsal tubercle, length 40 % of first toe length.

Dorsal coloration consisting of large irregular cream blotches arranged in the appearance of an interrupted dorsolateral band, on a dark-brown background; a large irregular blotch above vent; smaller cream blotches on the upper and lateral sides of the limbs; venter and ventral side of the limbs marbled with dark marking on a cream background, throat dark; palm of hands and feet homogenous gray.

Photos of live specimens (see below) agree entirely with the holotype, but blotches sometimes shows a more reddish to orangish coloration.

Comparison with other species of the genus

Comparing P. newtoni sp. nov. with P. bifasciatus View in CoL , the newly described species can be easily distinguished by having a dorsal pattern consisting of large irregular yellowish, red or silver blotches, sometimes arranged in the appearance of an interrupted dorsolateral band ( versus dorsal pattern consisting either of (A), two well marked and uninterrupted orangish to reddish dorsolateral bands on a homogeneous dark background, (B), two well marked and uninterrupted orangish to reddish dorsolateral bands, with faint vestiges of greyish dorsal bands, or (C), briefly interrupted orange dorsolateral bands on a homogeneous dark background (see Passmore & Carruthers 1979; Poynton & Broadley 1985; Auerbach 1987; Lambiris 1989; Channing 2001; Pickersgill 2007; Channing & Howell 2006; Spawls et al. 2006; Farook et al. 2014; Channing & Rödel 2019; see Table 2 View Table 2 ; see Fig. 4 View Figure 4 , 5 View Figure 5 , 10 View Figure 10 , 11 View Figure 11 ). Comparing P. newtoni sp. nov. with P. affinis View in CoL , the newly described species can be easily distinguished by having a dorsal pattern consisting of large irregular blotches ( versus small orange or red spots in P. affinis View in CoL ) and the tips of fingers expanded into disks ( versus tips enlarged but not forming disks in P. affinis View in CoL ; see Fig. 1b View Figure 1 ). Comparing it with P. annectens View in CoL , the newly described species can be easily distinguished by its larger blotches, having the tips of fingers expanded into round disks ( versus tips of fingers expanded forming small truncated disks in P. annectens View in CoL , see Fig. 2b View Figure 2 ) and by having the ventral coloration mottled with dark markings ( versus venter homogeneous pinkish-brown without spots in P. annectens View in CoL ). Comparing it with P. microps View in CoL , the newly described species can be easily distinguished by having a dorsal pattern consisting of large irregular blotches ( versus a dorsal pattern entirely red, sometimes with a fine median black line in P. microps View in CoL ). Phrynomantis newtoni sp. nov. can be distinguished from P. somalicus View in CoL by having the tips of fingers expanded into large disks ( versus tips of fingers expanded forming small truncated disks in P. somalicus View in CoL ).

Distribution

The species is known from low elevation (below 20 m) in the coastal areas of southern and central Angola, from Benguela to Luanda Province ( Fig. 12 View Figure 12 ). We tentatively accept the identification of the Quissange specimen cited by Bocage as representative of Boulenger’s “var. C” as a representative of the new species, but refrain from assigning the Benguela specimen to any form. As both of these specimens were lost in the fire that destroyed the Lisbon collection in 1978, these identifications cannot be confirmed without newly collected material from the same areas.

Habitat and natural history notes

The dominant habitats where the specimens have been collected is a typical western Angolan savannah, with sandy soils dominated by Adansonia digitata , Euphorbia conspicua , Acacia welwitschi and Combretum spp. , together with a good grass coverage ( Grandvaux-Barbosa 1970).

Etymology

The specific epithet newtoni is formed in the genitive masculine singular and honors the Portuguese naturalist and explorer Francisco Newton (1864–1909), who collected the holotype. We propose the Portuguese common name of “Rã de Borracha de Newton”, and the English common name of “Newton’s Rubber Frog ”.