Hyperolius tuberculatus (Mocquard)

Lötters, S., Schick, S., Scheelke, K., Teege, P., Kosuch, J., Rotich, D. & Veith, M., 2004, Bio-sketches and partitioning of sympatric reed frogs, genus Hyperolius (Amphibia; Hyperoliidae), in two humid tropical African forest regions, Journal of Natural History 38 (15), pp. 1969-1997 : 1974-1983

Hyperolius tuberculatus (Mocquard)

(figure 4)

This species is known from bush land and forest from Cameroon through

Equatorial Guinea, Gabon and the Republic of Congo to the eastern Democratic Republic of Congo ( Laurent, 1972, 1983; Schiøtz, 1999; Frétey and Blanc, 2000). A detailed comparison of the many populations has not been conducted. It seems probable that more than one species is involved. At least Schiøtz (1999) regarded the suggested taxa hutsebauti Laurent from the Democratic Republic of Congo and nimbae Laurent from the Ivory Coast as full species. After examination of the type specimens, we agree that H. nimbae represents a distinct taxon, but we did not find striking differences between H. tuberculatus and H. hutsbauti . Lötters et al. (2001) listed material of H. tuberculatus examined in this study from the Monts Cristal in Gabon as Hyperolius sp. A. This material is from a site close to the type locality (i.e. ‘Lambaréné’, Gabon). However, we have not compared it either with the holotype or with topotypic specimens. According to Schiøtz (1975, 1999), H. tuberculatus forms a subgroup within the species complex encompassed by H. viridiflavus (Duméril and Bibron) .

Diagnosis. (1) SVL males 27.9¡ 1.73 mm (25.9–31.5 mm, n ~7), one female 29.6 mm; (2) TIBL/SVL 0.52¡0.01 (0.5–0.54, n ~8), HW/SVL 0.32¡0.01 (0.3–0.33, n ~8); (3) dorsal surface more or less intensely scattered with warts (the least in the only available female), tuberculate below tympanic area; (4) snout shape dorsally nearly rounded and laterally rounded, nares visible from above; (5) E-N/EYE 0.76¡0.1 (0.62–0.89, n ~8), canthus rostralis straight from tip of snout to nostril and straight or slightly concave from nostril to eye; (6) tympanum covered by thick skin in males, distinct in female, TYMP/EYE in female 0.3; (7) FOOT/TIBL 0.88¡0.05 (0.78–0.92, n ~8); (8) foot webbing formula: 1(1), 2i(1) 2e(0), 3i(1) 3e(0–K), 4i(1) 4e(K–1), 5(0–K); hand webbing formula: 1(1), 2i/e(1), 3i(1–1K) 3e(1), 4(K–1); (9) PhJ and PhF are dorsally light brown with or without dark brown hour-glass pattern and/or irregular dark brown spots, ventrally cream to pink, usually with a white area proximal to the cloaca, inner sides of legs and arms reddish; the gular flap of males is light yellow to greyish or greenish yellow; the iris is brownish (information provided is based on collected material and numerous non-collected specimens of both sexes); (10) for sequence of 560 bp fragment of mitochondrial DNA of the 16S ribosomal gene see GenBank under AY323921 (~ZFMK 73144); (11) LTRF unknown.

Hyperolius hutsebauti , if valid, differs from H. tuberculatus in being darker. Hyperolius nimbae is more tuberculate over its dorsal surfaces than H. tuberculatus .

Life history. Hyperolius tuberculatus is nocturnal and arboreal. We found both males and females in large numbers during the night time from ca 18:00 to 01:00 at the shore of a large artificial lake in a semi-cleared area in primary forest. Males produced advertisement calls from near the ground up to w 0.5 m above ground from riparian vegetation (i.e. mainly reed). Couples in amplexus were observed. Eggs obtained from a pair in a plastic bag were ca 2.0 mm in diameter (without jelly) and half-pigmented. Because of the accumulation of so

In call duration, number of notes per call, note duration and notes per second, the mean¡SD is followed by the range. In and maximum values are provided. For oscillograms and sound spectrograms see figure 2A–H.

many breeding specimens at the same time, H. tuberculatus may be regarded an explosive breeder.

Advertisement calls recorded by us each consist of a single very short ‘peep’ note, composed of numerous pulses (figure 2C; table 1). Thus, they generally

coincide with data provided by Amiet (in Schiøtz, 1999) from Cameroon and Bosch et al. (2000) from Equatorial Guinea ( Bosch et al., 2000). However, frequency range and dominant frequency given by Bosch et al. (2000) is about 1000 Hz higher without overlap.

Vocalization data in Largen and Dowsett-Lemaire (1991) refer to Alexteroon hypsiphonus Amiet , not H. tuberculatus (M. J. Largen, personal communication).

Differentiation of sympatric species in the field

Adults of the three species can be best distinguished by characters (1), (3), (6) and (9). Hyperolius mosaicus and H. pardalis are smaller than H. tuberculatus . The former has a distinct tympanum and lacks hand webbing, unlike H. pardalis and H.tuberculatus (although females of the latter have a distinct tympanum). Hyperolius pardalis has smooth skin while that of the other two is warty. The colour pattern of each of the three taxa is unique (figures 1, 3, 4).

All three species possess clearly distinguishable advertisement calls as shown in figure 2A–C.

Partitioning of species

We lack information about temporal partitioning of the three tree frogs throughout the year. According to our data, all were active in January 2000 when breeding took place or was about to. Circadian activity was the same in the three species with calling behaviour after sunset.

We clearly noted spatial partitioning. All taxa were arboreal but strictly

restricted to different types of water body (figure 5).

Advertisement calls are most different in temporal parameters. Larger size

in H. tuberculatus may suggest other food resources than in H. mosaicus and H. pardalis .