Phrynobatrachus afiabirago, Ofori-Boateng & Leaché & Obeng-Kankam & Kouamé & Hillers & Rödel, 2018

Ofori-Boateng, Caleb, Leaché, Adam D., Obeng-Kankam, Bright, Kouamé, N’Goran Germain, Hillers, Annika & Rödel, Mark-Oliver, 2018, A new species of Puddle Frog, genus Phrynobatrachus (Amphibia: Anura: Phrynobatrachidae) from Ghana, Zootaxa 4374 (4), pp. 565-578 : 568-574

Phrynobatrachus afiabirago sp. nov.

Figs 2–3

Holotype. UWBM 0 5925, field number: ADL 3999), a male from Atewa Range , Ghana, 6.24246°N, - 0.5571°E (date = WGS84), 769 m asl, 26 May 2011, coll. C. Ofori-Boateng & A.D. Leaché.

Paratypes (15). UWBM 9042–9046; ZMB 86155– 86159 (males) and UWBM 9041 , UWBM 5924 , ZMB 86154 (females) collected from north-eastern (6°14'32.856"N, 0°33'25.56"W) and north-western part of the Atewa Range (6°7'40.7634"N, 0°37'44.04"W) respectively, April 2016, coll. C. Ofori-Boateng & A.D. Leaché ; ZMB 86160 (male), Atewa range, Atiwiredu , 06°12’22.7”N, 0°34’39.2’’W, 817 m asl, 7 June 2006, coll. N.G. Kouamé & C. Ofori-Boateng ; ZMB 73708 (male) and ZMB 73709 (female), Jukwa forest , south-western Ghana, 5°14’44.13’’N, 1°22’42.31’’W, coll. C. Ofori-Boateng & A. Hillers.

Diagnosis. The molecular results place the new species within Phrynobatrachus . Morphologically this genus is distinguished from the similar looking and often syntopic Arthroleptis and juvenile Ptychadena by the presence of a tarsal tubercle (absent in Arthroleptis and Ptychadena ); presence or absence of webbing (always absent in Arthroleptis ); lack of a black spot in the tympanal region (present in Arthroleptis ); lack of a median dorsal skin raphe (present in Arthroleptis ); and the lack of parallel dorsal ridges (present in Ptychadena ).

The new species is a small frog (<25 mm) with a short, pointed snout and warty skin; warts most prominent on back; snout-vent length (SVL) of adult males 17.2–20.3 mm, adult females measure 22.5–23.4 mm; mean index head width/SVL is 0.3 (0.3–0.4; N = 17); eyelid tubercles absent; tympanum present but indistinct; fingers without webbing; rudimentary pedal webbing; tips of fingers not or slightly enlarged; toes distinctly enlarged to discs; small inner metatarsal tubercle present, larger than outer metatarsal tubercle; distinct tarsal tubercle; males with a subgular vocal disc, extending to anterior chest, dusted in black or covered with dark black blotches; males with large white nuptial pads on dorsal surface of first finger, femoral glands absent; belly of both sexes with minute black dots to large black blotching on white background.

The new species differs genetically from other West African Phrynobatrachus by 5–19% in the investigated part of the 16S gene (see below). Superficially the new species resembles P. latifrons , but can be told apart by the more pronounced pedal webbing and the yellow throat of breeding males in the latter species. Genetically and morphologically closest to the new species are three other West African species: P. gutturosus , P. fraterculus and P. maculiventris . P. afiabirago sp. nov. males of the new species share with P. maculiventris a throat, that is either completely covered with blackish spots or completely dusted in black ( Figs. 2 , 3 , 4F ); in P. gutturosus the black coloration of the throat in males is typically restricted to the anterior throat and does not extend onto the chest ( Fig. 4B ; Chabanaud 1921; Rödel 2000). The throat of P. fraterculus males is dirty yellowish grey ( Fig. 4D ). The belly of P. afiabirago sp. nov. always shows some dark patterning, ranging from very few small black dots to being densely beset with large dark blotches ( Fig. 3 ). The belly of adult P. gutturosus is usually white or only exhibiting very few minute black dots ( Fig. 4B ); in P. fraterculus the belly is greyish white with few larger and smaller black dots along the edges and in the pectoral region ( Fig. 4D ); the belly of P. maculiventris is densely covered with huge black blotches, separated by white lines ( Fig. 4F ). Furthermore P. fraterculus and P. maculiventris differ from the new species by having a smooth or slightly granular back skin ( Figs. 4C, E ), in contrast to the presence of many distinct warts in P. afiabirago sp. nov. ( Fig. 2 ). The most distinctive feature, differentiating P. afiabirago sp. nov. from P. gutturosus , P. fraterculus and P. maculiventris , is the lack of femoral glands in males of the new species, present in males of the other three species.

From other West African Phrynobatrachus species P. afiabirago sp. nov. differs morphologically (for genetic differences see below) by small size (SVL <25 mm; versus adults equal or larger than 25 mm in: P. intermedius , P. liberiensis , P. plicatus , P. natalensis ); absence of a black lateral face mask (black face mask present in P. intermedius , P. plicatus ); absence of a spiny eyelid tubercle (present in P. annulatus , P. calcaratus , P. pintoi , P. taiensis , P. villiersi ); presence of distinct black lateral bands on flanks (shared with most P. latifrons and some other, but smaller species); throat of males with black markings, but not entirely black (males with yellow throat: P. alleni , P. latifrons ; uniform black or grey: P. liberiensis , P. plicatus , P. calcaratus , P. pintoi , P. villiersi , P. guineensis , P. phyllophilus , P. ghanensis , P. francisci , P. natalensis , P. tokba ; white or greyish: P. annulatus ; clear with darker stippling and without obvious vocal sac: P. brongersmai ); males with disc-like vocal sac skin extending to anterior chest (only shared with P. gutturosus , P. fraterculus , P. maculiventris , P. pintoi ); most individuals with larger black spots on white belly (shared with P. taiensis , P. ghanensis , P. pintoi , P. annulatus— at least some spots round with white centre, P. villiersi— black blotches on clear blue belly; some other Phrynobatrachus may have few small black spots); rough warty back skin (back skin smooth in P. fraterculus , P. maculiventris , P. hieroglyphicus ; sometimes smooth in breeding P. latifrons , P. tokba ); males without femoral glands (femoral glands present in males of P. gutturosus , P. fraterculus , P. maculiventris , P. taiensis , P. phyllophilus ); no longer or Xshaped scapular or dorsal ridges (scapular ridges long and converging towards mid-body, almost X-shaped: P. alleni , P. plicatus ); distinct but rudimentary webbing (webbing more developed in P. alleni , P. latifrons , P. francisci , P. natalensis , P. intermedius , P. liberiensis , P. plicatus , P. rainerguentheri ).

Holotype description ( UWBM 5925, all measures in mm; Fig. 2 A –C ). Typical, small, adult male Phrynobatrachus with short, slender-oval body shape; snout-vent length: 18.4 mm; short snout, rounded in dorsal and rounded to slightly protruding in lateral view; canthus rostralis rounded; loreal region slightly concave; headwidth directly behind the eyes: 7.1; eye-diameter: 2.0; distance eye-nostril: 1.7; distance eye-snout tip: 2.2; nostril closer to snout than to eye; tympanum present but indistinct, tympanum diameter: ~ 0.9, nearly half the size of eye diameter; femur: 8.2, shorter than tibio-fibulare: 10.9; foot including longest toe: 14.8; hand with large oval palmar and thenar tubercles; fingers with small roundish subarticular tubercles, no additional tubercles on hands; finger tips very slightly expanded without forming discs; relative finger length: III>I<II=IV; palmar webbing rudimentary, webbing only between the most basal phalange of each toe; small and oval inner and outer metatarsal tubercles present, the inner one being larger approximately 0.25 of shortest toe length; relative toe length: I<II<III=V<IV; toes expanded forming slightly triangular to roundish discs; tarsal tubercle present, size almost equal to outer metatarsal tubercle.

Dorsal skin slightly warty, two converging—in almost x-shape—pairs of scapular warts, followed by three pairs of smaller oval to roundish black warts along posterior back; pair of very small warts on posterior part of snout, edges of back, flanks and upper surfaces of hind limbs with smaller round warts on granular skin; eyelids faintly granular without a spiny tubercle; ventral skin smooth.

Colour in life. Overall coloration of dorsum light to dark bronze brown with numerous black spots scattered particularly along edges of dorsal warts; light vertebral line extending from dark inter-orbital band to almost vent; anterior canthal region black; a conspicuous broad black band extends from behind eye across tympanum region along flanks to groin; narrow area between this band and back light brown; narrow area from tympanum to groin and between the lateral band and belly light brown; dorsal parts of hind limbs brownish with one broad and 2–3 narrow black cross-bars on either thighs and lower legs; anterior legs light brown with very faint black markings; brown upper lip with black bars, two white spots below anterior and posterior edge of eye; lower mandible almost completely black with few minute white spots; posterior part of thighs with light longitudinal lines; throat with black blotches on dark grey background; pectoral region grey; belly white with larger and smaller black spots and blotches, posterior part of belly slightly lighter than anterior one; groin area, posterior-most part of belly and lower part of thighs yellowish orange with few black spots; antero-ventral part of thighs with black longitudinal line. Throat covered by disc like vocal sac skin, slightly extending to pectoral region; throat skin slightly granular without spines; dorsal part of first finger with light nuptial pad; femoral glands absent.

Colour in preservation: Pattern as in life but faded; black may turn into darker brown; yellowish-orange colour turns into beige or white.

Paratype variation (measures in mm, summarized in Tab. 1; see Figs. 2D , 3 ). Body shape and dimensions and colouration, mostly as in holotype; male snout-vent length ranges from 17.2–20.3, females from 21.8–23.4 mm; canthal region with or without black line; back colour varies from bronze brown to greyish brown, median yellowish to orange vertebral line always present, broadest at mid of back, edges often indistinctly delimitated; two to three black, broad cross bars on thighs and lower legs; anterior part of thighs often with clear longitudinal band; narrow to broader yellowish line turning down from dorsal hind leg insertion to middle of posterior part of thighs, from there as longitudinal line with dark borders to knee, rarely interrupted; male throats range from entirely black to densely covered with black blotches on dark grey ground, tip sometimes with clear spot, sometimes longitudinal folds parallel to lower mandible; female throats smooth, from almost dark brown to black within irregular white median line and few white spots to very light with several dark blotches; dark lower lips of females partly interrupted by clearer spots; pectoral region, belly and lower side of hind legs from densely best with larger or smaller dark brown to black botches to almost white with few dark spots; some individuals with a fine light longitudinal line on posterior part of thighs and from mid lower leg to heel; females with slightly more expanded finger tips, compared to males; webbing may vary slightly, web between toe 4 and 5 often extending along 1.5 to 2 phalanges.

In ZMB 73708 (male) and ZMB 73709 (female) from Jukwa, in life the yellowish-orange colouration of groin and ventral thighs was replaced by lemon green; posterior surfaces of thighs with lemon-green longitudinal bands; ventral spots on belly restricted to edges leaving 90% of belly clear white; in preservation colouration much faded, specimens partly shrunken due to preservation.

Genetics. The 16S alignment contained 538 bp and 111 variable sites (75 parsimony-informative). There is 100% bootstrap support for the monophyly of P. afiabirago sp. nov. ( Fig. 5 ). Phrynobatrachus afiabirago sp. nov. together with two undescribed taxa, P. aff. gutturosus (bootstrap = 84% and 83%), and P. maculiventris (bootstrap = 100%) formed a highly supported clade (bootstrap = 96%). The genetic diversity within P. afiabirago sp. nov. samples was low (average pairwise distance = 0.0016; F81 substitution model). The alignment for P. afiabirago sp. nov. comprised 533 bp with 3 variable sites (1 parsimony-informative). We found four unique haplotypes among the nine samples, but there was no geographic structure in the distribution of these haplotypes. For example, ZMB 73708 from Jukwa in western Ghana shared the same haplotype as UWBM 9043 from the Atewa Range in southeastern Ghana.

We finally compared the 16S sequence of the new species to all 20 West African Phrynobatrachus species for which genetic data have been published ( Table 2, average pairwise distance: mean + sd = 13.03 + 3.65%, range = 5.00–18.63%). Concerning described taxa, P. maculiventris (5.00% difference) and P. fraterculus (6.45%) were the genetically most similar taxa.

Habitat and natural history. Phrynobatrachus afiabirago sp. nov. always occurred around large forest ponds and forest swamps ( Fig. 6 ). The frogs were usually collected from around the stilt-like root system of trees along the bank of swamps, including palms. The altitudinal range of the species extended from 300–800 m asl in the Atewa Range, but they occurred as low as 135–250 m in the south-western Jukwa forest. The Atewa Range, type locality, is located in south-eastern Ghana, west of Lake Volta (Eastern Region, see Fig. 1 ). It is one of the highest upland forests in Ghana, characterized by an interconnecting series of hills that runs from north to south ( Swaine & Hall 1977). This unique area comprises mountain forest like vegetation, not occurring anywhere else in West Africa ( McCullough et al. 2007).

Distribution. Phrynobatrachus afiabirago sp. nov. is so far known from only two localities in the Ghanaian forest zone; the Atewa Range in south-eastern Ghana and the small (0.5 ha) Jukwa forest, situated near the Kakum National Park in south-western Ghana ( Fig. 1 ). We assume that it will occur in other forests of the area as well.

Etymology. The specific epithet honours Afia Birago, the mother of the first author for overcoming all odds as a widow, woman and a single parent to provide the highest level of education to all her eight children. Her tenacity and love for nature is a source of inspiration to the first author’s professional career. The specific epithet is treated as a noun in apposition. We suggest Afia Birago’s Puddle Frog as common name.

Phrynobatrachus alleni Parker, 1936 ZMB 73747 / GU457535 0.15141 Phrynobatrachus annulatus Perret, 1966 ZMB 73746 / GU457538 0.10581 Phrynobatrachus calcaratus (Peters, 1863) MVZ 245140 / EU075282 0.10177 Phrynobatrachus dispar (Peters, 1870) CAS 219386 / EU075278 0.08685 Phrynobatrachus francisci Boulenger, 1912 MVZ 249545 / GU457548 0.14781 Phrynobatrachus fraterculus ( Chabanaud, 1921) ZMB 73761 / GU457551 0.06405 Phrynobatrachus ghanensis Schiøtz, 1964 ZMB 70721 / GU457553 0.16203 Phrynobatrachus guineensis Guibé & Lamotte, 1962 MOR T13 / GU457555 0.15837 Phrynobatrachus gutturosus ( Chabanaud, 1921) MOR C11 / GU457556 0.11696 Phrynobatrachus intermedius Rödel, Boateng, Penner & Hillers, 2009 ZMB 71539 / GU457557 0.14615 Phrynobatrachus latifrons Ahl, 1924 ZMB 73753 / GU457559 0.18633 Phrynobatrachus liberiensis Barbour & Loveridge, 1927 ZMB 73768 / GU457562 0.15001 Phrynobatrachus maculiventris Guibé & Lamotte, 1958 ZMB 71592 / GU457563 0.05002 Phrynobatrachus natalensis (Smith, 1849) ZMB 73717 / GU457566 0.16584 Phrynobatrachus phyllophilus Rödel & Ernst, 2002 ZMB 73763 / GU457570 0.15328 Phrynobatrachus pintoi Hillers, Zimkus & Rödel, 2008 ZMB 76883 / JN813916 0.09848 Phrynobatrachus plicatus (Günther, 1858) ZMB 73742 / GU457575 0.15683 Phrynobatrachus rainerguentheri Rödel, Onadeko, Barej & Sandberger, 2012 ZMB 77742 / JQ954865 0.15515 Phrynobatrachus tokba ( Chabanaud, 1921) ZMB 73774 / GU457585 0.14155 Phrynobatrachus villiersi Guibé, 1959 ZMB 73740 / GU457589 0.10777

Figures

FIGURE 1. Distribution of Phrynobatrachus afiabirago sp. nov. in Ghana. The type locality is indicated by a circle, square and diamond mark localities where other individuals of the type series were collected; position of Ghana within West Africa (upper left) and the area within Ghana (lower left) where the new species occurs (right).

FIGURE 2. Ventral (A), dorsal (B), and dorsolateral (C–D) views of Phrynobatrachus afiabirago sp. nov. from the Atewa Range, Ghana (male holotype:A–C, UWBM 05925, and D: female paratype, UWBM 5924).

FIGURE 3. Variations in ventral pattern among males (A; from left to right UWBM 9044, 9045 and 9043) and females (B; from left to right UWBM 9042, 9041 and 5924) of Phrynobatrachus afiabiragosp. nov.

FIGURE 5. Phylogenetic relationship of Phrynobatrachus afiabirago sp. nov. with its closest congeners, based on mtDNA (520 bp fragment of the 16S gene; ML tree); nodes supported by bootstrap values? 50% are indicated; in parentheses: collection or field number/GenBank accession number.The out-group species used to root the tree, P.dispar, is not shown.

FIGURE 6. Habitats of Phrynobatrachus afiabirago sp. nov. from the Atewa Range (type locality, site 1 = A; and site 2 = B; compare Fig.1), south-eastern Ghana.

FIGURE4. West African Phrynobatrachus species,similar toPhrynobatrachus afiabirago sp. nov. Dorsal(A) and ventral (B) view of a male Phrynobatrachus gutturosus from Taï National Park, Ivory Coast; dorsal (C) and ventral (D) view of a male Phrynobatrachus fraterculus from Gola Rainforest National Park, Sierra Leone; and dorsal (E) and ventral (F) view of a male Phrynobatrachus maculiventris from south-eastern Guinea.