Petropedetes cameronensis Reichenow, 1874

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 : 30-35

Petropedetes cameronensis Reichenow, 1874

Figs. 3 b, 4, 8b, 9b, 10c, 12, 13

Platymantis cameronensis – Peters, 1875, Montasber. Preuss. Akad. Wiss. Berlin, 1875: 211 Hylambates cameronensis – Boulenger, 1882, Cat. Batr. Sal. Coll. Brit. Mus., Ed. 2: 137 Hylambates (Platymantis) cameronensis – Knauer, 1883, Naturgesch. Lurche: 111 Petropedetes cameronensis – Boulenger, 1900, Proc. Zool. Soc. London, 1900: 439 Petropedetes obscurus Ahl, 1924 , Zool. Anz., 58: 81-82

Material examined. ZMB 8222 (holotype) adult female, 1872-1873, Cameroon, Bimbia, coll. A. Reichenow; MHNG 918.52 (male), Cameroon, Buea, Grand Soppo, 26.IX.1938, coll. R. Mertens & J.-L. Perret; MHNG 1522.32-34 (3 males), 1522.35-37 (3 females), Cameroon, Maholé, Mungo, 28.III.1973, coll. J.-L. Perret; MHNG 1521.40 (male), Cameroon, Buea, 29.XI.1972, coll. J.-L. Perret; MSNG 29891 (male), Cameroon, Mt. Cameroon, Buea, app. 800–1200 m a.s.l., VI.-VII.1902, coll. L. Fea; ZFMK 8798-99 (2 females), Cameroon, Viktoria, II.1973, coll. W. Böhme; ZFMK 14980 (female), Cameroon, Fako, Buea, 20.- 22.III.1974, coll. W. Böhme & W. Hartung; ZFMK 15427 (male), Cameroon, Batoki, 28.II.1954, coll. M. Eisentraut; ZFMK 61343 (female), Cameroon, Ekundu-Kundu, 21.-27.II. l989, coll. M.T. O’Shea; ZFMK 69233 (female), Cameroon, Mt. Nlonako, above Nguengue, app. 1100–1200 m a.s.l., 23.XI.-6.XII.1998, coll. ALSCO-Expedition; ZFMK 78018 (female), Mt. Nlonako: Ekomtolo, app. 500 m a.s.l., XI.2000, coll. H.-W. Herrmann; ZFMK 78355-356 (2 males), 78360 (female), Cameroon, Mt. Nlonako, Ekomtolo, 1/ 5.IV.2001, coll. H.-W. Herrmann et al.; ZFMK 81153 (male), Cameroon, Mt. Nlonako, Ekomtolo, 27.V.2000, coll. M. Solbach; ZFMK 81154 (male), 18.VIII.2000, other data as ZFMK 81153; ZFMK 81555 (female), 81616-617 (2 males), 81614-615 (2 females), Cameroon, Mt. Nlonako: Ekomtolo, 3-7.II.2003, 4.V.2003, 10-11.XII.2002, coll. M. Plath; ZMB 21759, 55222 (2 males, syntypes of Petropedetes obscurus Ahl, 1924 ), Tscharra, Dana River, coll. Brenner; ZMB 73729-73730 (1 male, 1 female), Nigeria, Rhoko-forest, near Cross River National Park, II.2007, coll. A. Onadeko & M.-O. Rödel; ZMB 73727-72728 (2 females), Nigeria, Mbe Mountains, VI/ VII.2005, coll. A. Onadeko.

Problematic material: ZSM 159/1988/1-2 (2 specimens, sex unknown), Cameroon, Victoria, II.1978, coll. F. Sauer.

Diagnosis. Small sized Petropedetes with compact body shape; snout short; tympanum very small, rather indistinct; characters of breeding males: tympanic papilla absent; carpal spike absent; forearm hypertrophy not developed; only Central African Petropedetes without spinosity; femoral glands oval shaped; toes approximately half-webbed: 1 (0) 2 (0-0) 3 (0-0) 4 (1.5-1.5) or 4 (2-2) 5 (0) or 5 (0.5) ( Fig. 10 c).

Description. Small sized Petropedetes with compact body; females distinctly larger than males (SUL in males: 26.8–34.8 mm, in females: 34.2–49.0 mm); mean head width in males about 37% of SUL, in females about 38%; snout in lateral view rounded to slightly pointed; canthus rostralis sharp; loreal region concave; eye diameter about 1.7 times distance eye-nose; nose closer to snout tip than eye; tympanum very small, rather indistinct in both sexes (tympanum / eye in males: 0.31–0.42, in females: 0.28–0.48); no tympanic papilla in breeding males; 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, palmar tubercle sometimes indistinct; dorsal skin structure heterogeneous with larger warts on the flanks; few large and longitudinal warts on back; ventral skin smooth; mean femur length in males 51% of SUL, in females 52%; mean tibia length in both sexes 60% of SUL; mean foot length in both sexes 76% of SUL; upper hind limbs of moderate size; lower hind limbs slender; oval femoral glands larger in males than in females (femoral gland / femur in males: 0.30–0.50, in females: 0.22- 0.31, Fig. 9 b); no secondary sexual characters other than femoral gland size known; relative length of toes: IV> III> V> II> I; half-webbed species, toe IV with up to two phalanges free of webbing: 4 (1.5-1.5) or 4 (2- 2); toe V with up to half phalange free of webbing: 5 (0) or 5 (0.5).

Coloration. Dorsum with pale spots or light brown colours ( Fig. 8 b); one specimen (ZFMK 78355) with dark brown ground colour and small pale dots of about 1 mm; iris golden; flanks can possess white coloured warts; legs coloured similarly as dorsum, but with larger dark bars; throat whitish or dark marbled; belly yellowish grey; coloration in preservation as in life but pale; belly whitish with minuscule speckles, the latter especially dense in the breast region, almost absent on abdomen (recognizable only with dissecting microscope).

Tadpole. According to Boulenger’s (1906) figure of the mouth of an advanced P. c a m e ro n e n s i s tadpole the labial-tooth-row formula is 2:1+1//1+1:2 ( Fig. 3 b); mouth bordered by papillae; papillae row with a median gap on lower lip. Schiøtz (1966) presents a tooth formula for a still tailed tadpole with fully developed hind limbs as 3+3//1+1:2. The tail length of this specimen is more than 2.5 as long as the body; tail without traces of ventral fin, only a very narrow dorsal fin ( Schiøtz 1966).

The tadpole assignments of both authors appear reliable, as the species is easily recognizable by the extent of the webbing. Boulenger (1906) even lists another species in his work and Schiøtz (1966) additionally describes the call of adult specimens of P. cameronensis .

Natural history. Petropedetes cameronensis occurs mainly in the lowland, but is also known from localities up to 1400 m, where it was found together with P. p e r re t i ( Amiet 1973). On Bioko the species is known from mid-altitude, but may also occur in the coastal zone ( Boulenger 1906; Mertens 1965). Schiøtz (1963) collects specimens at night on stones in a fast-flowing stream and Amiet (1975) finds the species in rapids and waterfalls. The call of P. cameronensis has been described as a whistle ( Schiøtz 1966) or a trill that drowns the noise of torrents ( Amiet 1989). Eggs of P. cameronensis are deposited on tree trunks or leaves close to humid rocks, where the saxicolous (living on rocks) tadpoles develop ( Amiet 1989). Herrmann et al. (2005) observe males guarding clutches from February to May on Mt. Nlonako. Schiøtz (1966) assumes that the muscular tail without or only narrow fin allows the tadpole to jump on stones.

Distribution. In the original description the type locality is given as Bimbia, Cameroon, which has been specified by Perret (1984) as Bimbia, Victoria (= Limbe); and hence the coastal Cameroonian lowland south of Limbe. Schiøtz (1963) calls the type locality “Bimba, Cameroons ”, which is probably a misspelling. This mistake has been further developed as “Bima, Cameroons ” by Frost (2009). P. c a m e ro n e n s i s is also known from moderate altitudes ( Lawson 1993), even reaching heights above 1100 m on Mt. Nlonako ( Herrmann et al. 2005). The species is known from areas in eastern Nigeria ( Schiøtz 1963; Perret 1984) and western Cameroon (e.g. Boulenger 1906; Perret 1966; Fig. 4 ). Amiet (1973) assumes that the Sanaga River may be the species’ eastern distributional border. P. cameronensis has also been recorded from Bioko ( Boulenger 1906; Mertens 1965).

Genetics. The genetic comparison for the uncorrected p-distances of the mitochondrial 16S rRNAfragment (Table 4) gave the following results for Petropedetes cameronensis : interspecific comparison between P. cameronensis and all other Central African Petropedetes taxa ranged between 5.96%-9.25%, while the intraspecific variation within P. cameronensis was much lower at 0.00%-0.50% (N= 4).

Systematic remarks. Ahl (1924) describes Petropedetes obscurus from Tscharra, Dana River and distinguishes this half-webbed species from P. cameronensis by the size of its tympanum, which is only one third of the eye diameter in P. obscurus and half the diameter in P. cameronensis . Perret (1984) who studies the validity of P. obscurus , erroneously changes the type locality to Ishiara, Tana River, Kenya. Based on the morphology of the two syntypes (2 males: ZMB 21759, ZMB 55222) he concludes that the diagnostic characters of Ahl (1924) are not sufficient and consequently placed P. obscurus in the synonymy of P. cameronensis . Our examination of the type specimen of P. obscurus confirmed Perret’s (1984) decision. Hence, an affiliation of the two specimens to the East African Arthroleptides , as assumed by Klemens (1998), can be rejected. Both specimens clearly possess vomerine teeth, already mentioned in Ahl’s description (1924, Fig. 12 ). The placement of the type locality into East Africa must, however be rejected. As such, the type locality remains mysterious. The only Tscharra that we found (www.fallingrain.com) is in Austria (zoogeographically impossible). There are various settlements called Dana in Nigeria, Cameroon, Chad and Central African Republic, however, all in the dry savanna regions.

Herrmann (1989) publishes a list of amphibian types in the Zoological Museum, Greifswald (ZIMG) and lists among others, Petropedetes cameronensis . He gives the “ type locality” of this frog as Bonjongo. Our examination of this frog (Acc Cat I – 3411) revealed that it differs from the description of Reichenow (1874).

The holotype from ZIMG is bleached out and the femoral glands are hard to identify, but other characters are still recognizable. The tympanum does not possess a papilla, but although being smaller than the diameter of the eye, it is clearly distinct. An even more striking character differentiating this frog from Reichenow’s description is the lack of webbing. These characters are already sufficient to show that this frog cannot be an additional P. cameronensis type. The ZIMG frog is also much smaller than the frog described and figured in Reichenow (1874). Whereas Reichenow (1874) mentions 120 mm, the ZIMG specimen reaches a length of only 82 mm from the tip of the snout to the tip of the toe ( Fig. 13 ). The ZIMG specimen probably belongs to P. johnstoni , which would match with the locality on the foot of Mt. Cameroon. Apparently Herrmann (1989) lists a specimen collected by Buchholz in “ Mai 73 ” (May 1873) from Bonjongo, but misidentifies it. The only identifiable type of P. cameronensis , collected by Reichenow (1874) himself is stored in the ZMB.

Petropedetes cameronensis is half-webbed and possesses an indistinct tympanum lacking a tympanic papilla in males. Hence, P. cameronensis is easy to distinguish from the rudimentary-webbed species with a tympanic papilla P. euskircheni sp. nov., P. johnstoni , P. p a r k e r i and P. vulpiae sp. nov. The species could potentially be mistaken with P. palmipes due to its indistinct tympanum, but differs from P. palmipes by its smaller size, less developed webbing (toes fully webbed in P. p a l m i p e s) and lacking a carpal spike ( Amiet 1973). Although having a similar webbing, P. c a m e ro n e n s i s can be unambiguously distinguished from P. juliawurstnerae sp. nov. alike (see the following species description).

Figures

FIGURE 3. Tadpole morphology (scale bar mouth 1 mm; scale bar habitus 10 mm): a) P. johnstoni (MSNG 50032; Gosner stage: 41; total length: 26.3 mm); b) P. c a m e ro n e n s i s (modified after Boulenger 1906; tadpole with fully developed hind limbs; no scale bar); c) P. p e r re t i (ZMB 73738; Gosner stage: 28; total length: 24.4 mm); d) P. palmipes (modified after Lamotte et al. 1959); change of denticulation: left: early tadpole stage; centre: tadpole with posterior extremities of 10 mm; tadpole habitus (total length: 22 mm).

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 8. Life coloration of Central African Petropedetes with developed webbing: a) Petropedetes perreti (male: Mt. Manengouba, Cameroon; female: Nguengue, Mt. Nlonako, Cameroon), b) P. cameronensis (left: Limbe, Cameroon; right: Rhoko-forest, Nigeria), c) P. juliawurstnerae sp. nov. (male and female: Nyasoso, Mt. Kupe, Cameroon, d) P. palmipes (left male: Monte Alen, Equatorial Guinea; photo: I. de la Riva; right male: Bipindi, Cameroon; photo: H. - W. Herrmann).

FIGURE 9. Relation of femoral gland to femur and shape of femoral gland in Central African Petropedetes with developed webbing: a) Petropedetes perreti (male: ZFMK 69215; female: ZFMK 69211), b) P. cameronensis (male: ZFMK 81616; female: ZFMK 81555), c) P. juliawurstnerae sp. nov. (male: ZFMK 67360; female: ZFMK 68134), d) P. palmipes (male: MHNG 1033.28; female: MHNG 1033.5).

FIGURE 10. Development of webbing of a) Petropedetes perreti (ZFMK 69217), b) P. juliawurstnerae sp. nov. (ZFMK 68170), c) P. cameronensis (ZFMK 81555).

FIGURE 12. Vo m e r i n e s i n P. obscurus (synonym of P. cameronensis) (marked by arrow; ZMB 55222).

FIGURE 13. Various Petropedetes specimens; from left to right: holotype of P. c a m e ro n e n s i s (ZMB 8222); P. cameronensis “ type ” (ACC Cat I – 3411), and types of P. obscurus (ZMB 21759, ZMB 55222).