hear Fonozoo call

Description
Scotobleps gabonicus is a Central African frog with a maximum snout–vent length of 52 mm for males and 70 mm for females (Channing and Rödel 2019). This species has a large head (approximately as long as it is broad), pointed snout, short canthus rostralis, large eyes, and small tympanum. Vomerine teeth appear in two small groupings just posterior to the choanae. The first finger is approximately as long as the second finger. The toe tips are round with a moderate amount of webbing on the feet, and there are pronounced subarticular tubercles.The dorsal skin is smooth with small flat warts (Boulenger 1900, Channing and Rödel 2019).

The dorsum is typically colored olive-brown with small black spots. A dark cross-band is present between the eyes. The upper lip of the frog has black vertical bars, with one below the anterior third of the eye extending to the lower lip. Dark cross bars are present on the limbs. The ventral side of the frog is white in coloration (Boulenger 1900, Channing and Rödel 2019).

Similar to Astylosternus and Trichobatrachus, Scotobleps bears recurved bony claws (the terminal phalanx). While this is found on toes II - V in Astylosternus and Trichobatrachus, in Scotobleps it is developed only on toes II and III (Amiet 1977, Blackburn et al. 2008).

There are no known external secondary sexual characters, such as nuptial pads, that are unique to males or females of S. gabonicus (Amiet 1977). Thus, sex must be determined either by dissection or by determining the presence of vocal slits in males. Males of the species have internal vocal sacs (Boulenger 1900).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Cameroon, Congo, Congo, the Democratic Republic of the, Equatorial Guinea, Gabon, Nigeria

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (80 records).

This terrestrial and usually abundant species is found throughout eastern Nigeria (Onadeko et al. 2010), western Democratic Republic of Congo (Laurent 1965), western and southern Cameroon (Amiet and Perret 1969, Amiet 1975, 1978, 1983, 1986), mainland Equatorial Guinea (Sánchez-Vialas et al. 2020), and western Gabon (Burger et al. 2006, Deichmann et al. 2017). Its presence has been confirmed through surveys in the following areas: in Gabon, Doumaye, and Mboua in South Eastern Gabon (Jongsma et al. 2017), Monts Doudou (Burger et al. 2004), Crystal Mountains National Park, Lopé National Park, and Moukalaba- Doudou National Park (Pauwels and Rödel 2007); in Nigeria, Afi Forest Reserve and Ikpan forest ecosystem near the Cross River (Rahman et al. 2020), and Oban Hills and Mbe Mountains near the Cross River (Onadeko et al. 2010); in Cameroon, Mt Kupe (Portik et al. 2016, Herrmann et al. 2005), Ebo Forest, Korup National Park (Griesbaum et al. 2019), Mt. Nlonako (Plath et al. 2004); and in the Republic of Congo, Lebayi, Lékoumou (Zassi-Boulou et al. 2019).

This species is common in lowland rainforests throughout the area (IUCN 2017), rarely reaching above 600 m (Amiet and Goutte 2017). Most individuals are found in the leaf litter or close to clear streams with a sandy bottom (Amiet and Perret 1969), as opposed to muddy water (Jongsma et al. 2017), but can be found in rocky torrents and streams with silty bottoms (Amiet and Schiøtz 1973).

Life History, Abundance, Activity, and Special Behaviors
Males of the species have internal vocal sacs (Boulenger 1900). Males call at night, typically within 1 – 2 m of river and stream banks (Amiet and Schiøtz 1973, Amiet and Goutte 2017). October through December is an active period for male advertisement calls with less activity from January through June (Amiet 2006). Calls are a brief (~98 – 100 ms) and nasal “coâ” that can be emitted in isolation or in a small series (Amiet and Schiøtz 1973), increasing in frequency modulation (De la Riva et al. 2001). Calling and breeding take place in wide shallow streams with sandy banks and flowing water (Amiet and Goutte 2017, IUCN 2017).

Although primarily located near streams, when threatened, the frog does not use the stream for shelter; instead, it remains in place or moves away from the stream (Jongsma et al. 2017).

Eye-shine of the frogs can be used to detect adults at night (Jongsma et al. 2017).

Despite extensive use of pit-fall traps in Gamba, Gabon, S. gabonicus was never recovered in a pit-fall trap by Burger et al. (2006).

Similar to the closely related genera Astylosternus and Trichobatrachus, the phalanges of Scotobleps are claw-shaped and used for defense. While this is found on toes II-V in Astylosternus and Trichobatrachus, in Scotobleps it is developed only on toes II and III (Blackburn et al. 2008).

Scotobleps gabonicus is known to have nyctothere parasites, Prosicuophora basoglui (Affa’a and Amiet 1990, 1994).

Larva
Tadpole total length is about 60 mm with body length approximately 32.6 ± 1.0% of total length. The labial tooth formula is 1:2/2:2. The mouth is ventral and close to the snout. Papillae are present on the posterior lip and small lobes are present on each corner of the mouth; there is a large rostral gap with papillae present. The large fully keratinized jaws are sharply serrated. The upper jaw sheath is rectangular with 2 – 3 enlarged fangs on each side, whereas the lower jaw is v-shaped and lacking a central notch (Griesbaum et al. 2019).

The coloration of the tadpole body is brown with grayish lateral sacs and light brown speckles present towards the tail tip. Fins range from a yellowish brown to dark red brown (Griesbaum et al. 2019).

Tadpoles are found in small to medium-sized streams and rivers located in lower altitude forests (Amiet 1986, 1989).

Trends and Threats
Threats to S. gabonicus include loss of forest habitat leading to possible population declines. Activities such as logging, wood harvesting, and agriculture contribute to habitat loss (IUCN 2017). Additionally, because these frogs prefer clear streams as opposed to muddy water, this suggests that the species would be sensitive to heavy sedimentation and erosion caused by deforestation and other anthropogenic activities (Jongsma et al. 2017).

Comments

Phylogenetic relationships:

References
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Species Account Citation: AmphibiaWeb 2024 Scotobleps gabonicus <https://amphibiaweb.org/species/1504> University of California, Berkeley, CA, USA. Accessed Nov 25, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Nov 2024.

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