Phrynobatrachus ruthbeateae sp. nov.

Figs. 1–2

Holotype. ZMB 77457 (field # 0 801, adult male), Cameroon, near Dja Biosphere Reserve, N 03°24.257’, E 013°08.314’, 659 m a.s.l., primary swampy evergreen rainforest, 30 April 2009, coll. M.-O. Rödel, T. Doherty-Bone, M. Talla Kouete, P. Janzen, K. Garrett, R. Browne.

Paratypes. ZMB 77458-77459 (field # 0 808, adult male; 0 817, adult female), 1 May 2009, other data as holotype; ZMB 77460 (field # 0 826, adult female), N 03°23.139’, E 013°07.608’, 650 m a.s.l., 2 May 2009, other data as holotype.

Additional material. LG 0 785, female, SVL: 13.3. mm, N 03°28.052’, E 013°03.425’, 684 m a.s.l, small swamp and river near campsite, 28 April 2009, other data as holotype; LG 0 825, female, SVL: 14.6 mm, other data as ZMB 77460.

Diagnosis. The 16S rRNA sequence data indicates that the new species is a member of the genus Phrynobatrachus . Morphologically this is visible by the body shape; presence of a tarsal tubercle; presence of webbing; lack of a median dorsal skin raphe, lack of a black spot in the tympanal region; lack of parallel dorsal ridges; neither finger nor toe tips heart shaped.

The new species is characterized by a combination of small size; compact body shape; short round snout; black lateral face mask; males with a black throat, the anterior part beset with large flat black spines; females with white throat and uniform black lower mandible; absence of eyelid cornicle; larger warts on upper eyelids; scapular ridges converging in straight line; rest of dorsal skin slightly granular to smooth; flanks with large white warts; white belly; groin area and lower parts of thighs yellow; absence of nuptial pads in males; distinct discs on finger and toe tips; well developed webbing and 16S rRNA sequence.

Description of holotype [measures in mm]. Typical, small adult male Phrynobatrachus with long oval, compact body shape; snout-vent length: 17.8; short snout, rounded in dorsal and lateral view; canthus rostralis rounded; loreal region straight; head-width directly behind the eyes: 6.3; medium sized eyes positioned laterally; eye-diameter: 2.8; distance eye-nostril: 1.5; nares small and round, positioned laterally; distance nostril-snout tip: 1.0; nostril closer to snout than to eye; internarial distance: 2.1; interorbital distance: 2.2; pupil round; supratympanal ridge ranging from posterior corner of eye to forearm bases; tympanum diameter: 1.0, round and indistinct, much smaller than diameter of eye; upper and lower maxillae and praemaxillae with minute teeth, hidden by lips; vomerine teeth absent; broad cordiform tongue, tip distinctly notched, median papilla near anterior attachment of tongue; small round choanae.

Forelimbs slender; upper arm: 4.0; lower arm: 3.4; hand to tip of finger III: 4.6; hand with large carpal tubercles, inner oval, outer round; carpal gland absent; fingers with small roundish subarticular tubercles, no additional tubercles on hands; relative finger length: II=IV<I<IIII; manual webbing absent; finger tips broadened, forming small discs; thumbs (finger I) slightly swollen, no distinct nuptial pads; hind limbs short and slender; femur: 8.5, slightly shorter than tibia: 8.9; tibia length 50% of SVL; foot including longest toe: 12.3; femoral glands absent; tarsal tubercle present; large internal metatarsal tubercle: 1.0, long and narrow, app. 2/3 of length of toe I: 1.5; small round external metatarsal tubercle; relative toe length: I<II<V<III<IV; digits with well developed basal webbing; webbing formula I(0.5), II(1), III(1.5), IV(2.5–3), V(1), skin fringes extending further towards toe tips; toe tips enlarged to discs.

Dorsal skin fine granular (in life) to smooth (in preservation); a pair of straight scapular ridges, ranging from about posterior corner of upper eyelid to level of forearm bases, converging towards vent in a straight line; smaller pair of comma shaped warts positioned dorsolaterally and posterior to level of forearm bases; posterior 2/3 of eyelid with larger round warts, eyelid cornicle absent; white spines or warts on flanks; skin on lower parts of limbs, belly and pectoral region smooth; throat with lateral skin folds running parallel to mandibles along posterior 2/3 of the latter; anterior half of lower mandible and anterior 2/3 of throat densely beset with large rounded black spines.

Colouration in life (Fig. 1 a–b): Basic colour of dorsal surface of head, upper part of flank, back and dorsal surfaces of extremities being a beige brown; only dorsal part of feet brown-orange; black lateral face mask extending from snout tip, below canthus, eye and supratympanal ridge to forearm bases, covering tympanum; continuing below arms as a lateroventral black band to almost groin region; posterior part of interorbital space with a indistinct band being darker than remaining parts of back; anterior to this band a narrower lighter line in-between eyelids; black pupil surrounded by lighter red-golden ring; iris golden; dorsal part of thighs with five (right) and four (left) dark cross-bars; shanks with four (right) and three (left) dark cross-bars; posterior part of dorsal skin on thighs uniform dark brown; vent surrounded by broad black triangle, extending towards belly; throat black; pectoral region white with few minute black points; belly white, bordered by black ventrolateral band; ventral part of lower arm black; other ventral surfaces of forelimbs gray; groin area and lower surfaces of thighs yellowish to orange; lower part of thighs anterior laterally bordered by black line; ventral surfaces of feet dark brown.

Colouration in ethanol after almost two years: pattern only slightly fainted.

Variation (Fig. 1 c–h). Snout-vent length in males 17.2–17.8 mm and 13.3–19.7 mm in females (smallest one presumably not adult); body dimensions generally as in holotype (Table 1). Females with thinner fingers, i.e. finger I; discs on fingers more conspicuous than in males; relative finger length in paratypes: I<II=IV<III; there is some variation in the webbing formulae (Table 1), however pedal webbing always distinct but never being very extended; dorsal pattern of males almost uniform light brown to reddish brown; dorsal pattern with beige flanks and black back and upper part of head in females; scapular ridges partly with dark edges; lower arms in paratypes darker than upper arm; iris golden, red or dark gray; dorsal skin granular to slightly warty in both sexes; scapular ridges in one male (ZMB 77458; Fig. 1 c) less conspicuous than in other vouchers, in contrast these ridges seem to extend along the dorsolateral line in both females (ZMB 77459-77460; Fig. 1 e, g), whereas the scapular ridges are very distinct in the life animals, these “extensions” are not visible in preservation; females with white and smooth throat, lower mandibles uniform black, no spines on throat; ZMB 77460 with white flat warts on flanks as in males.

Genetics. Phrynobatrachus ruthbeateae sp. nov. differed between 4.5–23.0% in the sampled region of the 16S rRNA gene from 34 West African and Central African species of the genus Phrynobatrachus (Table 2). The species with highest genetic similarity to P. ruthbeateae sp. nov. all occur in Central Africa. The uncorrected pairwise sequence divergence to the most similar species was: P. chukuchuku (4.9%), P. w e r n e r i (5.1%), P. steindachneri (5.2%), P. schioetzi (5.6%), P. batesii (5.9%), P. cricogaster (5.5%), P. danko (6.1%), and P. manengoubensis (6.1%), respectively. The intraspecific variation of P. ruthbeateae sp. nov. ranged from 0.0–1.2% (Table 2).

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TABLE 2. (continued)

Distribution and conservation status. Phrynobatrachus ruthbeateae sp. nov. is so far only known from the type locality (Fig. 3). However, it is very likely that the new species is widespread in western Central African lowland rainforests, south of the Sanaga River at least. For instance Burger et al. (2004) list and illustrate a small Phrynobatrachus (P. sp. 2) from forests between 350–660 m a.s.l. on the Monts Doudou, Gabon. These frogs might be conspecific with the species described herein; the only visible difference being a large yellow blotch on upper lip and loreal region. The Gabon frogs were calling during day and sunset in muddy terrain near small streams. Given the presumed large range in huge tracks of still undisturbed rainforest, the new species probably is of Least Concern according to the IUCN RedList criteria (IUCN 2001). However, currently P. ruthbeateae sp. nov. must be classified as Data Deficient until this predicted range is confirmed.

Natural history. All specimens of P. ruthbeateae sp. nov. were observed in the rainy season during daytime in swampy primary rainforest (Fig. 4). Four individuals were recorded under closed canopy at the edge of large palm swamps. One female was collected within a large swamp in an area with small trees, palms forming an open canopy. Males were calling during the day, sitting very close to small puddles, well concealed below leaves. Calling males were widely spaced from each other. Unfortunately the call could not be recorded, however, to the human ear it sounded almost identical to the call of P. phyllophilus, consisting of a fast series of brief metallic clicks (Rödel & Ernst 2002). The presence of parasitic, subcutaneous mites on the posterior part of the belly and on the thighs (Fig. 1 b, f) indicates that the species is indeed mostly living in swamps: this family of Endotrombiculidae occur on many African Phrynobatrachus species, but are most abundant on species dwelling in very wet or humid environments (Spieler & Linsenmair 1999; Wohltmann et al. 2007; MOR, unpubl. data).

Other Phrynobatrachus species living in syntopy with the new species were P. africanus, calling from more central parts of the swamps, and P. cornutus, living in drier parts at the edge of the swamps. Annual rainfall at the type locality summed to app. 1700 mm with highest peaks of precipitation from March-July and September-November. Annual mean of daily minimum temperature was about 19°C (rarely dropping to 16°C, never reaching 21°C); the annual mean of daily maximum temperature was about 26°C (rarely dropping to 23°C, never exceeding 31°C).

Etymology. The first author dedicates this species to his mother, Ruth-Beate Rödel. Without her continuous support his scientific career would have never been possible.