Petropedetes euskircheni, Barej, Michael F., Rödel, Mark-Oliver, Gonwouo, Legrand Nono, Pauwels, Olivier S. G., Böhme, Wolfgang & Schmitz, Andreas, 2010

Barej, Michael F., Rödel, Mark-Oliver, Gonwouo, Legrand Nono, Pauwels, Olivier S. G., Böhme, Wolfgang & Schmitz, Andreas, 2010, Review of the genus Petropedetes Reichenow, 1874 in Central Africa with the description of three new species (Amphibia: Anura: Petropedetidae), Zootaxa 2340, pp. 1-49 : 26-28

Petropedetes euskircheni sp. nov.

Figs. 1 d, 2d, 4, 6b, 7d

Holotype. ZFMK 75582 (adult male), Cameroon, Mt. Kupe, Nyasoso, 4°49’42N, 9°40’55E, app. 920 m a.s.l., 15.I.2000, coll. H.-W. Herrmann & A. Schmitz.

Paratypes. IRSNB-KBIN 1988 (male), Cameroon, Mt. Kupe, Nyasoso, 4°49’42N, 9°40’55E, app. 925 m a.s.l., 18.XII.1997, coll. O. Euskirchen; MHNG 2713.7 (male), Cameroon, Mt. Kupe, Nyasoso, 4°49’42N, 9°40’55E, app. 950 m a.s.l., 5.VII.2009, coll. A. Schmitz & M.F. Barej; MHNG 2713.11 (female), same data as holotype; ZFMK 67344 (female), same data as IRSNB-KBIN 1988; ZFMK 68152, (male), 68156 (female) Cameroon, Mt. Kupe, NW-slope, app. 910 m a.s.l., 4°49’42N, 9°40’55E, 18.XII.1997 – 03.I.1998, coll. A. Schmitz; ZMB 73693 (male), same data as ZFMK 68152.

Additional material examined. ZFMK 67347-348 (2 females), Cameroon, Mt. Kupe, Nyasoso, app. 920 m a.s.l., 19.XII.1997, coll. O. Euskirchen; ZFMK 68153-155 (1 male, 2 females), same data as ZFMK 68151; ZFMK 69207-208 (2 females), Cameroon, Mt. Nlonako, above Nguengue, app. 1100–1200 m a.s.l., 23.XI.- 6.XII.1998, coll. ALSCO-Expedition; ZFMK 69497 (female), Cameroon, Mt. Nlonako, above Nguengue, app. 1200 m a.s.l., 2.XII.1998, coll. ALSCO-Expedition; ZFMK 75539 (female), Cameroon, Mt. Nlonako, Nguengue, app. 1100 m a.s.l., 18.-21.I.2000, coll. H.-W. Herrmann & A. Schmitz; ZFMK 75583 (subadult male), same data as holotype; ZFMK 78365 (female), Cameroon, Mt. Nlonako, Ekomtolo, 3.IV.2001, coll. H.-W. Herrmann et al.; ZFMK 81103 (female), Cameroon, Mt. Nlonako, XI.2000 – I.2001, coll. H.-W. Herrmann & M. Solbach; ZFMK 81168 (female), Cameroon, Mt. Nlonako, Ekomtolo, 24.VIII.2000, coll. M. Solbach.

Diagnosis. Large sized Petropedetes ; robust body shape; tympanum rounded or slightly flattened on the upper and lower borders, almost equal to or larger than eye in males, always smaller than eye in females; characters of breeding males: tympanic papilla present (broad and fleshy), closer to upper border of tympanum; forearm hypertrophy strongly developed; carpal spike present; tegumental spinosities developed on throat, forearms and hardly on the anterior part of the dorsolateral side ( Fig. 6 b); femoral glands very small (smallest in Central African Petropedetes ), usually shifted to the posterior part of the femur, glands can be indistinct in both sexes; webbing rudimentary.

Description of the holotype. The holotype is an adult male in breeding condition with a robust body shape and broad head; 54.9 mm SVL; snout in lateral view short, rounded; head width 22.4 mm; eye diameter 6.9 mm; interorbital distance 5.6 mm; naris closer to snout (3.5 mm) than to eye (5.4 mm); femur length 46.4 mm; tibia length 35.6 mm; foot (incl. longest toe) 46.6 mm; femoral glands small (length x width: 4.8 x 2.8 mm / 4.6 x 2.9 mm, holotype with especially large glands); femoral glands turned slightly to the posterior side of the femur; relation femoral gland length to femur length: 0.16; spinosities well developed on throat, upper lips and breast, upper forearms and flanks ( Fig. 6 b); dorsal skin texture heterogeneous with small warts and few larger, longitudinal warts; venter smooth; flanks with rough warts; webbing rudimentary; coloration of preserved specimen: dorsum pale, marbled with dark spots; hind limbs with transversal white lines, these continuing on lower legs; throat dark; venter whitish; femoral glands with few darker markings.

Variation. Large sized Petropedetes with robust body, second largest species of the genus; males larger than females (SUL in males: 44.3–62.0 mm, in females: 38.6–57.3 mm); mean head width in males 40% of SUL, in females 39%; snout in lateral view generally rounded, obtuse; canthus rostralis distinct but slightly rounded; loreal region concave; eye diameter about 1.5 times distance eye-nose; nose closer to snout tip than to eye; distinct tympanum, usually flattened on upper and lower border of tympanum (tympanum / eye in males: 0.97–1.19, in females: 0.49–0.85); tympanum surrounded by minuscule white warts; tympanic papilla close to upper border of tympanum; papilla broad and fleshy with oval basis; supratympanic fold distinct; fingers slender, with typically T-shaped fingertips; relative length of fingers: III> IV> II> I; manual subarticular tubercles single; manual webbing absent; palmar tubercle and thenar tubercle present; forearm hypertrophy strongly developed in males; carpal spike present in males, spinosities developed on throat, upper lips and forearms, few spinosities on dorsolateral parts of flanks; skin structure heterogeneous, larger warts on flanks; larger longitudinal warts present on dorsum, in some specimens arranged in lines; ventral skin smooth; mean femur length in males 51% of SUL, in females about 53%; mean tibia length in males 60% of SUL, in females about 62%; mean foot length in males 80% of SUL, in females 82%; upper hind limbs moderateslender; lower hind limbs slim femoral glands very small (smallest in genus), of similar size in both sexes (femoral gland / femur in males: 0.12–0.21, in females: 0.10–0.16); relative length of toes: IV> III> V> II> I; webbing rudimentary: 1 (1) 2 (1-1) 3 (2-2) 4 (3-3) 5 (2).

Coloration. Dorsum dull, most often brown-black or almost uniformly marbled brown-olive ( Fig. 1 d); thin white band between eyes, partly proceeded posteriorly by broader dark band; femora with dark spots, divided by thin pale lines; lines continuing on lower legs; venter whitish; femoral glands are coloured pale orange or brown, as hind legs; coloration in preservation: dorsum uniform, mainly blackish-grey; belly whitish with minuscule spots (less dense than in other species), throat dark or whitish with darker pigments in males, of same colour as belly or slightly darker pigmented in females.

Natural history. Specimens with unambiguous determination have been found in high numbers at a watercatchment at Mt. Kupe about 910 m altitude ( Euskirchen et al. 1999, Fig. 7 d). Adults and juveniles occurred in syntopy with P. v u l p i a e sp. nov. and P. juliawurstnerae sp. nov. Specimens of P. euskircheni sp. nov. were found at night on slippery, steep stones close to rapids or in the riverine vegetation on leaves in a height of 20–180 cm. Disturbed frogs flee into water.

Distribution. Currently, this species is only known with certainty from Mt. Kupe and Mt. Nlonako ( Fig. 4 ). Specimens from the two localities differ slightly genetically, but form one clade compared to the remaining members of the genus (see below). Morphologically they are indistinguishable. The two populations are consequently regarded as conspecific herein. The type locality of the species is on Mt. Kupe.

Genetics. Morphologically, P. euskircheni sp. nov. resembles P. p a r k e r i. To confirm the proposed species status a genetic comparison of the two species with uncorrected p-distances of the mitochondrial 16S rRNA gene (611 bp, including gaps) has been calculated. The differences for the two species are as follows: interspecific comparison of 16S rRNA ranged between 5.94-8.69% (N euskircheni = 9, N parkeri = 4); the intraspecific variation was 0.00%-3.14% (N= 9) in P. euskircheni sp. nov. and 0.00%-0.22% (N= 4) in P. parkeri . Thus the interspecific differences between these two taxa are well within the general range of interspecific genetic differences between other species of the genus (Table 4).

The intraspecific variation within the 16S rRNA of P. euskircheni sp. nov. was higher than in the other taxa. Specimens within the P. euskircheni sp. nov. -clade formed two locality based (Mt. Kupe and Mt. Nlonako) subclusters (Table 4). Calculated for each locality only, the specimens from each cluster showed the same low within site variability as in other Central African Petropedetes species (Mt. Kupe: 0.00%-0.39%; Mt. Nlonako: 0.00%; Table 4). The genetic differences between vouchers from Mt. Kupe and Mt. Nlonako could not be backed up with morphological characters. At present male specimens are only known from Mt. Kupe. As only males in breeding condition allow determination with certainty, we refrain from taxonomically distinguishing specimens from the Mt. Kupe and Mt. Nlonako. To ensure a clear taxonomic status for future work, only specimens from the type locality (Mt. Kupe) have been included in the type material.

Systematic remarks. Petropedetes euskircheni sp. nov. is rudimentary-webbed and therefore easily distinguishable from species with developed webbing (P. p a l m i p e s and P. p e r re t i, both fully webbed; P. cameronensis and P. juliawurstnerae sp. nov., both half-webbed). The presence of a distinct tympanum and a tympanal papilla distinguish P. euskircheni sp. nov. from P. cameronensis and P. palmipes , which lack these characters. In addition to this character it can be separated by the size of the femoral gland from P. vulpiae sp. nov. and P. johnstoni , which both possess larger femoral glands (in both sexes) (femoral gland length / femur length in males: N euskircheni = 7, N vulpiae = 35, p <0.001; N johnstoni = 7, p <0.01 in females: N euskircheni = 16, N vulpiae = 16, p <0.001; N johnstoni = 4, p <0.01). Moreover, males of P. euskircheni sp. nov. grow larger than P. vulpiae sp. nov. and P. johnstoni (SUL: N euskircheni = 7, N vulpiae = 35, p <0.001; N johnstoni = 7, p <0.01).

Most likely the new species can be mistaken with P. parkeri . Both species are morphologically similar and have small femoral glands. However, the femoral glands are distinctly smaller in P. euskircheni sp. nov. Main distinguishing characters of P. euskircheni sp. nov. from P. parkeri are: a) the size of femoral gland: femoral glands are small but distinct in males of P. parkeri , while they are very small and more shifted to the posterior side of the limb in P. euskircheni sp. nov. (see Table 1); the femoral gland length / femur length ratio is smaller in P. euskircheni sp. nov. than in P. p a r k e r i (in males N euskircheni = 7, N parkeri = 11, p <0.01; in females: N euskircheni = 16, N parkeri = 7, p <0.001); b) the head width / SUL ratio in P. euskircheni sp. nov. is significantly broader (in males N euskircheni = 7, N parkeri = 11, p <0.01; in females: N euskircheni = 16, N parkeri = 7, p <0.001), although values overlap with P. parkeri ; moreover the head shape is more flattened in P. parkeri , i.e. larger parts of the tympana are visible in dorsal view than in P. euskircheni sp. nov.; c) the tibia length / SUL ratio in P. euskircheni sp. nov. is higher in both sexes (in males N euskircheni = 7, N parkeri = 11, p <0.01; in females: N euskircheni = 16, N parkeri = 7, p <0.001); d) the foot length / SUL ratio in P. euskircheni sp. nov. is higher in both sexes (in males N euskircheni = 7, N parkeri = 11, p <0.01; in females: N euskircheni = 16, N parkeri = 7, p <0.001); e) the spinosity of the skin seems to be more developed on the dorsum of male P. euskircheni sp. nov. (as the exact breeding status of most vouchers is unknown, this character has to be used with caution); f) maximum snout-urostyle-length: P. parkeri are larger; up to 74 mm, the largest P. euskircheni sp. nov. male reaches 62 mm; however overall SUL does not differ significantly (p = 0.71) between the species; g) the shape of the tympanum is usually rounder in P. parkeri than in P. euskircheni sp. nov., where it is slightly flattened or oval in three of four specimens (but less than in P. v u l p i a e sp. nov.).

Petropedetes euskircheni sp. nov. is most similar to P. p a r k e r i and has been mixed up with the latter species (e.g. Euskirchen et al. 1999) in the past. The co-occurrence of two similar species makes a clear assignment of different localities to a taxon difficult (see above). Amiet (1983) mentiones P. p a r k e r i from localities at higher elevations north of Mt. Kupe and Mt. Nlonako (from Foto Ndonchwet, Mbakang, Bangwa). As the only available male specimen in breeding condition from Bangwa (MHNG 1521.60) possesses large femoral glands, and no molecular comparisons could be applied, we tentatively assign these specimens to P. aff. parkeri ( Fig. 4 ).

Etymology. The specific epithet euskircheni is a patronym. The species is named after Dipl.-Biol. Oliver Euskirchen, who accompanied A. Schmitz during fieldwork in 1997/98.

Figures

FIGURE 1. Life coloration of rudimentary-webbed Central African Petropedetes. a) Petropedetes johnstoni (male and female: Nkoelon, Cameroon), b) P. vulpiae sp. nov. (male and female: Nyasoso, Mt. Kupe, Cameroon), c) P. parkeri (male Nguti, Cameroon; female: Amebishu, Cameroon) d) P. euskircheni sp. nov. (male: Nyasoso, Mt. Kupe, Cameroon; female: Nguengue, Mt. Nlonako, Cameroon).

FIGURE 4. Distribution of known Petropedetes species; compare with text. Specimens from localities marked with an asterisk (*) were not available and are added from literature.

FIGURE 6. Portraits of holotypes showing spinosity: a) Petropedetes vulpiae sp. nov. (ZFMK 81623), b) P. euskircheni sp. nov. (ZFMK 75582), c) P. juliawurstnerae sp. nov. (ZFMK 67360).

FIGURE 7. Habitat pictures and specimens of uncertain determination: a) Petropedetes parkeri, Mamfe region, Cameroon; b) P. vulpiae sp. nov. biotope, waterfall at Itsila, Gabon – Republic of Congo border; c) P. vulpiae sp. nov., cascade 15 km north of Alen-Nkoma, right of Route L. 107, Kango Department, Estuaire Province, Gabon (photo: J. P. Vande weghe); d) type locality of P. juliawurstnerae sp. nov. and P. euskircheni sp. nov., habitat of P. vulpiae sp. nov., Nyasoso, Mt. Kupe, Cameroon; e) P. vulpiae sp. nov., cascade at Big Massaka, Cameroon; f) P. aff. parkeri, Barrage de Tchimbélé, Gabon (ZFMK 73132; photo: V. Gossmann); g) P. cf. johnstoni near Langoué Bai, Gabon (no voucher; photo: J. P. Vande weghe):