Odontobatrachus ziama Barej, Schmitz, Penner, Doumbia, Hirschfeld, Brede, Bangoura & 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 : 124-127

Taxon classification Animalia Anura Odontobatrachidae

Odontobatrachus ziama Barej, Schmitz, Penner, Doumbia, Hirschfeld, Brede, Bangoura & Roedel sp. n.

Odontobatrachus ziama OTU1 sensu Barej et al. (2015)

Holotype.

ZMB 78300 (male), Republic of Guinea, Ziama Classified Forest (Latitude: 8.35790; Longitude: -9.29993), 668 m a.s.l., 22 November 2008, coll. C. Brede, M.A. Bangoura and J. Doumbia.

Paratypes.

Guinea: ZMB 78298 (female), N’Zérékoré Region (8.36; -9.31), 878 m a.s.l., 11 July 2011; ZMB 78299 (female), same data as holotype; ZMB 78301, ZFMK 95464-65, MHNG 2731.46 (4 females), N’Zérékoré Region (8.36; -9.29), 558 m a.s.l., 30 July 2010; ZMB 78302, MHNG 2731.45 (2 males), N’Zérékoré Region (8.49; -9.31), 960 m a.s.l., 5 August 2010.

Additional material.

Guinea: ZMB 78251 (male), ZMB 78252 (female), Kankan Region (9.21; -8.93), 1119 m a.s.l.; ZMB 78253-58 (5 females), N’Zérékoré Region (7.98; -9.12), 472 m a.s.l.; ZMB 78259 (female), Kankan Region (8.982; -8.96), 606 m a.s.l.; ZMB 78260, ZMB 78263, ZMB 78264 (juvenile), ZMB 78265-7 (5 females), ZMB 78261-2, ZMB 78268-9 (4 males), Kankan Region (9.26; -8.93), 754 m a.s.l.; ZMB 78271 (juvenile), N’Zérékoré Region (8.55; -9.08), 529 m a.s.l.; ZMB 78272 (male), Kankan Region (9.16; -8.93), 999 m a.s.l.; ZMB 78273 (male), ZMB 78274-5 (2 females), N’Zérékoré Region (8.89; -8.62), 646 m a.s.l.; ZMB 78276-7 (2 females), ZMB 78278 (juvenile), N’Zérékoré Region (8.55; -8.90), 1201 m a.s.l.; ZMB 78279-80 (2 females), N’Zérékoré Region (8.85; -8.89), 937 m a.s.l.; ZMB 78281 (female), ZMB 78282 (male), N’Zérékoré Region (8.82; -8.86), 726 m a.s.l.; ZMB 78283 (juvenile), N’Zérékoré Region (8.52; -8.94), 600 m a.s.l.; ZMB 78284 (male), ZMB 78285-6, ZMB 78288 (3 females), ZMB 78287 (juvenile), N’Zérékoré Region (8.53; -8.91), 1310 m a.s.l.; ZMB 78289-91 (3 males) ZMB 78292 (female), N’Zérékoré Region (8.14; -8.57), 622 m a.s.l.; ZMB 78295 (female), N’Zérékoré Region (8.28; -8.74), 908 m a.s.l.; ZMB 78296 (male), ZMB 78297 (female), N’Zérékoré Region (8.33; -8.71), 701 m a.s.l.

Diagnosis.

Medium sized frogs, robust body shape; head narrow, smallest tympanum diameter/eye diameter ratio in the family, webbing fully developed, leaving up to 0.5 of the distal phalange free at the inner side of toe II, leaving up to 0.5-0.75 of the distal phalange free at toe IV; male femoral glands dark orange; glandular lines on tibia contain minuscule to small conic glands forming a pretty continuous line, belly pattern highly variable. Genetically Odontobatrachus ziama differs by a minimum of 2.89% in the mitochondrial 16S gene from its congeners.

Differential diagnosis.

Odontobatrachus ziama can be distinguished from its congeners by a combination of characters (for all significant differences see Table 5): SUL in Odontobatrachus ziama is smaller than in Odontobatrachus smithi and Odontobatrachus fouta (Tables 1 and 2); male Odontobatrachus ziama differ from their congeners in the following ratios (Table 1): HW/SUL smaller than in Odontobatrachus natator , Odontobatrachus smithi and Odontobatrachus fouta ; TD/O smaller than in Odontobatrachus natator and Odontobatrachus smithi ; O/EN larger than in Odontobatrachus natator and Odontobatrachus smithi ; TD/SUL smaller than in Odontobatrachus natator ; GL/GW smaller than in Odontobatrachus smithi but larger than in Odontobatrachus fouta ; female Odontobatrachus ziama differ from their congeners by the following ratios (Table 2): HW/SUL smaller than in Odontobatrachus natator , Odontobatrachus smithi and Odontobatrachus fouta ; TD/O smaller than in Odontobatrachus natator , Odontobatrachus smithi , Odontobatrachus fouta and Odontobatrachus arndti ; O/EN larger than in Odontobatrachus natator , Odontobatrachus smithi and Odontobatrachus fouta ; TD/SUL smaller than in Odontobatrachus natator , Odontobatrachus smithi and Odontobatrachus fouta . Webbing of Odontobatrachus ziama is more more extensive than in Odontobatrachus natator , less extensive than in Odontobatrachus smithi and Odontobatrachus fouta and possesses a similar extent to Odontobatrachus arndti (Table 7). Femoral glands are dark orange in Odontobatrachus ziama but rose-coloured in Odontobatrachus natator , pale orange in Odontobatrachus smithi and bright orange in Odontobatrachus fouta (Figs 4, 6, 8, 10). Glandular lines on tibia contain minuscule to small conic glands forming almost continuous lines (Fig. 6 a–d), while small to large glands form more or less interrupted lines in Odontobatrachus natator (Fig. 4 a–e), small to mean conic glands form predominantly interrupted lines in Odontobatrachus smithi (Fig. 8a, b), small to large glandular conic glands, rather interrupted lines in Odontobatrachus fouta (Fig. 10b, c). and similar to Odontobatrachus ziama small to mean glandular conic glands form hardly interrupted lines in Odontobatrachus arndti (Fig. 12b, c). Morphologically the species is most similar in size and colour pattern to Odontobatrachus arndti (Table 7); however, they differ in several mensural characters: male Odontobatrachus ziama have larger SUL, but smaller HW, TD, O and extremities (FM, TI, FL); female Odontobatrachus ziama have smaller HW, O, ID and extremities (FM, TI, FL).

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 ziama and other Odontobatrachus species range from 2.89-5.41%, while maximum intrataxon differences of Odontobatrachus ziama add up to 0.38% (mean value 0.18%; N = 496; Appendix 1: Table A).

Holotype description.

The male holotype has been correctly assigned to this taxon in both DCA analyses (absolute values and ratios). The holotype is an adult male with a moderately robust body shape (Fig. 5): snout-urostyle length of 46.1 mm; head width 15.5 mm; head slightly longer than broad; snout in lateral view short, flattened and slightly pointed at the snout tip; snout in dorsal view pointed; lower jaw with sharp tusk-like prolongations and single small knob at lower jaw symphysis with corresponding socket in between premaxillae; upper premaxillae and maxillae with numerous teeth, posteriorly curved; vomerine teeth present, arranged in two small odontophores, closer to each other than to choanae; tongue broadly heart shaped; horizontal eye diameter 6.5 mm; interorbital distance 4.8 mm; pupil horizontally elliptical; eye diameter distinctly larger than tympanum diameter; tympanum indistinct (horizontal diameter 3.5 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 moderately slender, forearms slightly hypertrophied, fingers slender; prepollex absent; relative finger lengths III>IV>II>I; velvety nuptial excrescences on finger I weakly developed; subarticular tubercles large, subconical; supernumerary tubercles absent; fingertips dilated, triangular, notched in the middle; femur length 24.1 mm; tibia length 24.4 mm; femoral glands large (length × width: left: 12.7 × 7.6 mm, right: 12.8 × 7.5 mm); femoral glands positioned on the posterior part of the ventral side of femur; relation femoral gland length to femur length: 0.53; minuscule circular glands running along upper side of tibia; foot length (incl. longest toe) 32.0 mm; relative toe lengths IV>III≥V>II>I; shortest toe 5.5 mm; inner metatarsal tubercle elliptical; toe tips broadened forming triangular dilated discs; inner metatarsal tubercle prominent (3.7 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 heterogeneous; dorsum and flanks covered with slender dorsal ridges of app. 2.6 mm length (partially flattened, but recognisable as darker spots); venter smooth; flank texture as on dorsum; webbing fully developed (0-0.25/0-0.75/0-1/1.25-0); webbing between toes hardly concave. Damage to the male holotype: left femur (in dorsal view) with short cut; third toe of left foot (in dorsal view) clipped for tissue sample; glandular dorsal ridges partially not recognisable due to preservation.

Colouration of holotype in alcohol

(Fig. 5). Dorsum brownish, marbled with small dark spots (partially indicating presence of former dorsal gland ridges), a pale marking between shoulders; hind limbs on upper side with large dark blotches, surrounded with blurred pale lines; throat dark showing pale markings of scratches (scars); venter dark; femoral glands pale, clearly contrasted against femora, with few minuscule dark dots; femora and tibia dark as belly.

Variation.

Females are significantly larger than males (SUL: Z = -4.164, p <0.001, Nmales = 11, Nfemales = 30), mean SUL in females 52.1 mm and 45.1 mm in males, and consequently possess longer extremities (FM: Z = -3.649, p <0.001; TI: Z = -4.665, p <0.001; FL: Z = -3.694, p <0.001), broader heads (HW: Z = -3.638, p <0.001), longer snouts (EN: Z = -3.261, p <0.01; ES: Z = -2.402, p <0.05) and larger eyes (O: Z = -2.431, p <0.05) in absolute measurements (Tables 1 and 2). However, ratios are predominantly similar between the two sexes, although males show higher values in FL/SUL (Z = -2.119, p <0.05), FM/SUL (Z = -1.883, p = 0.06), HW/SUL (Z = -3.119, p <0.01) and TD/SUL (Z = -1.942, p = 0.52). 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. Male femoral glands are dark orange (Fig. 6f). Several specimens marked as males in the field lacked obvious secondary sexual characters (femoral glands) and flanks were opened to assess primary sexual characters. Probably due to preservation, femoral glands were not contrasted against the femora, and skin of vocal sacs shrivelled and retracted; however, one male showed no trace of skin modification on femora even if the typical gland position was cut open (ZMB 78262). Webbing formulae show very extensive webbing (Table 7). However, few specimens show a little reduced webbing on toe IV leaving almost the whole distal phalange free (1/1). Dorsal ridges are either long and slender (Fig. 6 a–c) or are roundish and knob-like (Fig. 6d). Number of distinct dorsal ridges (counted from spine to flank) ranges between three and seven, usually four to five ridges per body site. However, both characters were not recognisable due to preservation artefacts in many specimens. Glandular ridges on tibia are usually built of small to large conic glands and form more or less interrupted lines (Fig. 6 a–d). Dorsal colouration (in life) varies from uniform dark brown or olive, to dark brownish with pale irregular markings, to ochre with brownish spots and dorsal ridges are set off in terms of colour by usually being darker than the remaining dorsum (Fig. 6; Rödel and Bangoura 2004). Male femoral glands are dark orange (Fig. 6f). Belly colouration (in alcohol) is very variable, ranging from completely pale, to dirty smeared pale-dark, to pale reticulation on dark belly, to dark throat and pale belly, to dark throat and belly with pale longitudinal lines to dark with few pale markings, to completely dark, showing no sex-dependant differentiation.

Distribution.

Distribution of Odontobatrachus ziama is restricted to isolated mountains north of the Nimba Mts. in south-eastern Guinea (Fig. 1). Its range apparently overlaps with Odontobatrachus natator as the latter is found in proximity to the Simandou Mountain Range, Massif du Ziama or Mt. Going. However, no syntopic populations are known so far. At present no differing habitat requirements or ecological adaptations are known ( Barej et al. 2015), which could explain their spatial separation. Presence of Odontobatrachus natator in lower altitudes (e.g. Liberia, Grand Gedeh 250-500 m a.s.l.) could be a factor but both species co-occur in altitudes of app. 500-1300 m a.s.l. in the distribution range of Odontobatrachus ziama .

Natural history remark.

Odontobatrachus ziama is known as a host of the endoparasitic mite Endotrombicula pillersi , otherwise known from members of the family Phrynobatrachidae ( Wohltmann et al. 2007).

Etymology.

The species epithet ziama is a noun in apposition, therefore invariable, referring to the species' type locality, the Ziama Forest, in eastern Guinea.

Common name.

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

Conservation status.

The EOO of Odontobatrachus ziama is 7797 km2, placing the species in the category "Vulnerable (VU)" while the AOO of 104 km2 classifies the species as "Endangered (EN)" ( Barej et al. 2015).