Odontobatrachus fouta Barej, Schmitz, Penner, Doumbia, Brede, Hillers & Roedel

Barej, Michael F., Schmitz, Andreas, Penner, Johannes, Doumbia, Joseph, Sandberger-Loua, Laura, Hirschfeld, Mareike, Brede, Christian, Emmrich, Mike, Kouame, N'Goran Germain, Hillers, Annika, Gonwouo, Nono L., Nopper, Joachim, Adeba, Patrick Joel, Bangoura, Mohamed A., Gage, Ceri, Anderson, Gail & Roedel, Mark-Oliver, 2015, Life in the spray zone - overlooked diversity in West African torrent-frogs (Anura, Odontobatrachidae, Odontobatrachus), Zoosystematics and Evolution 91 (2), pp. 115-149 : 131-134

Taxon classification Animalia Anura Odontobatrachidae

Odontobatrachus fouta Barej, Schmitz, Penner, Doumbia, Brede, Hillers & Roedel sp. n.

Odontobatrachus fouta OTU3 sensu Barej et al. (2015)

Holotype.

ZMB 78314 (adult male), Republic of Guinea, Fouta Djallon, Labé, Sala (Latitude: 11.29389; Longitude: -12.50178), 916 m a.s.l., 18 July 2010, coll. C. Brede and J. Doumbia.

Paratypes.

Guinea: ZMB 78314, MHNG 2731.48 (2 females), same data as holotype.

Additional material.

Guinea: ZMB 78316 (female), same data as holotype; ZMB 78317-18 (2 males), Mamou Region (10.82; -12.19), 760 m a.s.l.; ZMB 78319 (juvenile), Labé Region (11.29; -12.51), 882 m a.s.l.; ZMB 78320, ZMB 78323 (2 females), ZMB 78322 (male), ZMB 78321, ZMB 78324-5 (3 juveniles), Mamou Region (10.34; -12.17), 652 m a.s.l.

Diagnosis.

Medium to large sized frogs, robust body shape; head narrow, low mean eye diameter/eye-naris distance ratio, highest tympanum diameter orbita diameter ratio in the family, webbing fully developed, leaving 0.75 of the distal phalange free at the inner side of toe II, leaving the distal phalange at toe IV free; belly colouration typically dark, male femoral glands bright orange; glandular lines on tibia contain mean conic glands forming frequently interrupted lines. Genetically Odontobatrachus fouta differs by a minimum of 3.79% in the mitochondrial 16S gene from its congeners.

Differential diagnosis.

Odontobatrachus fouta can be distinguished from its congeners by a combination of characters (characters distinguishing Odontobatrachus smithi vs. Odontobatrachus ziama and Odontobatrachus fouta see above; for all significant differences see Table 5): SUL in Odontobatrachus fouta is larger than in Odontobatrachus natator and Odontobatrachus arndti (Tables 1 and 2); male Odontobatrachus fouta differ from their congeners by the following ratios (Table 1): GL/GW smaller than in Odontobatrachus natator and Odontobatrachus arndti ; TD/O and O/EN smaller than in Odontobatrachus natator ; female Odontobatrachus fouta differ from their congeners by the following ratios (Table 2): TD/O larger than in Odontobatrachus natator and Odontobatrachus arndti ; O/EN smaller than in Odontobatrachus natator and Odontobatrachus arndti ; ES/O and TD/SUL larger than in Odontobatrachus arndti . Webbing in Odontobatrachus fouta is generally less extensive than in Odontobatrachus natator and shows less webbing on the inner side of toe II than in Odontobatrachus arndti (Table 7). Femoral glands are bright orange in Odontobatrachus fouta but rose-coloured in Odontobatrachus natator , pale orange in Odontobatrachus smithi and dark orange in Odontobatrachus ziama (Figs 4, 6, 8, 10). Glandular lines on tibia contain small to large glandular conic glands, rather interrupted lines (Fig. 10b, c), while similar to Odontobatrachus fouta small to large glands form more or less interrupted lines in Odontobatrachus natator (Fig. 4 a–e), and small to mean glandular conic glands form hardly interrupted lines in Odontobatrachus arndti (Fig. 12b, c).

Genetics.

The species is genetically well differentiated from all congeners and known populations form a well-supported and monophyletic clade ( Barej et al. 2015). Uncorrected 16S p-distances between Odontobatrachus fouta and other Odontobatrachus species range from 3.79-4.98%, while maximum intrataxon differences of Odontobatrachus fouta reach 0.36% (mean value 0.15%; N = 55; Appendix 1: Table A).

Holotype description.

The male holotype has been assigned to this taxon in both DCA analyses (absolute values and ratios). The holotype is an adult male with a robust body (Fig. 9): snout-urostyle length of 55.6 mm; head width 21.6 mm; head slightly longer than broad; snout in lateral view short, flattened and slightly rounded; snout in dorsal view triangular, tip fairly rounded; lower jaw with sharp tusk-like prolongations protruding the skin and single triangular knob at lower jaw symphysis, corresponding socket in between premaxillae weakly developed; upper premaxillae and maxillae with numerous teeth, posteriorly curved; vomerine teeth present, single prolongations; odontophores arranged in short lines, closer to each other than to choanae, skin around vomerine teeth dark; tongue broadly heart shaped; horizontal eye diameter 7.7 mm; interorbital distance 5.9 mm; pupil horizontally elliptical; eye diameter distinctly larger than tympanum diameter; tympanum distinct (horizontal diameter 3.1 mm); nares closer to snout than to eye; snout as long as eye diameter; canthus rostralis rounded; loreal region concave; paired lateral vocal sacs; forelimbs robust, forearms hypertrophied, fingers slender; prepollex absent; relative finger lengths III>IV>II>I (Fig. 9); velvety nuptial excrescences covering finger I; subarticular tubercles large, subconical; supernumerary tubercles absent; fingertips dilated, slightly triangular; femur length 27.8 mm; tibia length 28.9 mm; femoral glands large (length × width: left: 14.2 × 8.0 mm, right 14.3 × 8.7 mm); femoral glands positioned on the posterior part of the ventral side of femur; relation femoral gland length to femur length: 0.51; minuscule circular glands running along upper side of tibia; foot length (incl. longest toe) 38.0 mm; relative toe lengths IV>III≥V>II>I (Fig. 9); shortest toe 7.2 mm; inner metatarsal tubercle elliptical; toe tips broadened forming triangular dilated discs; inner metatarsal tubercle prominent (4.5 mm); number of subconical subarticular tubercles on toes I-V: 1, 1, 2, 3, 2; supernumerary tubercles absent; prominent skin fold on posterior side of feet; dorsal skin texture rough; dorsum and flanks covered with slender dorsal ridges of app. 2.0-5.0 mm, mainly positioned dorsolaterally (partially flattened); venter somewhat rough and slightly granular; flank texture rough and granular as dorsum; webbing fully developed (0-0.75/0-1/0-1/1-0), skin fringe running along toe III, webbing between toes hardly concave. Damage of the male holotype: transverse cut at pectoral region (liver tissue sampled); glandular dorsal ridges partially not recognisable due to preservation.

Colouration of holotype in alcohol

(Fig. 9). Dorsum dark brownish; hind limbs with dark blotches on upper side, few pale lines recognisable; entire dirty blurred dark and pale, with several scratches (scars); venter as throat on the anterior part, more reticulated pattern on the belly; colouration between axillaries and elbows brighter; femoral glands pale, clearly silhouetted from femora, with blurred minuscule dark dots, posterior part darker; femora and tibia dark as belly.

Variation.

Females (Nfemales = 4) grow larger than males (Nmales = 3), maximum SUL in females 62.5 mm and 57.0 mm in males, and absolute values for extremities are accordingly larger, too (Tables 1 and 2). However, males and females have similar ratios and mean values. Both sexes possess enlarged tusk-like prolongations in the lower jaw as well as the name-bearing ‘teeth’ on the upper jaw. Male secondary sexual characters are femoral glands, velvety nuptial excrescences on finger I and presence of vocal sacs. Webbing formulae showed little variance (Table 7). Dorsal ridges are short and knobbed (Fig. 10a) or elongated and slender (Fig. 10b). Number of distinct dorsal ridges (counted from spine to flank) ranges between three and six ridges per body site, usually four to five ridges per body site. However, this character was not recognisable due to preservation artefacts in all specimens. Glandular ridges on tibia usually are built of small to large conic glands and form rather interrupted lines (Fig. 10b, c). Dorsal colouration (in life) ochre coloured with dark brown markings along dorsal glandular ridges or almost uniform dark with few whitish markings along flanks and on dorsum. Male femoral glands are bright orange (Fig. 10d). Belly colouration (in alcohol) is mainly uniform dark, only few specimens possess paler markings or show a dirty smeared colouration, showing no sex-dependant differentiation.

Distribution.

The distribution of Odontobatrachus fouta is restricted to isolated peaks in the central Fouta Djallon Highlands in western Guinea (Fig. 1). Localities of Odontobatrachus natator at the southern edge and of Odontobatrachus smithi close to western-central of the Fouta Djallon Highlands are in close proximity to Odontobatrachus fouta . However, Odontobatrachus fouta occurs in higher altitudes (southern edge: Odontobatrachus natator app. 500 m a.s.l. and Odontobatrachus smithi app. 92 m a.s.l. vs. Odontobatrachus fouta app. 650 m a.s.l.; western-central: Odontobatrachus smithi app. 510-650 m a.s.l. vs. Odontobatrachus fouta app. 750-900 m a.s.l.).

Etymology.

The species epithet fouta is a noun in apposition, therefore invariable, referring to the species' type locality, the Fouta Djallon Highlands, in western Guinea.

Common name.

We advise to use the term ‘‘ Fouta Djallon torrent-frog’’ in English and ‘‘ grenouilles des torrents de Fouta Djallon" in French.

Conservation status.

Both, the EOO of 1318 km2 and the AOO of 20 km2 classify Odontobatrachus fouta as "Endangered (EN)" ( Barej et al. 2015).