Phrynobatrachus cricogaster Perret, 1957
This species name is derived from the Greek 'krikos' meaning ring and 'gaster' meaning belly and refers to the prominent ring pattern present on the venter.
Phrynobatrachus cricogaser is a medium sized (snout–vent length < 32 mm) species of puddle frog from the highlands of Cameroon and Nigeria. Members of this genus are identified by the presence of a midtarsal tubercle, elongate inner metatarsal tubercle, and outer metatarsal tubercle. This species can be further identified by its 4-5 additional tarsal tubercle, one which forms a small spur with the heel, and distinct bullseye ventral pattern.
The IUCN Redlist (2009) categorizes this species as Vulnerable because its Extent of Occurrence is less than 20,000 km2, its distribution is severely fragmented, and there is continuing decline in the extent and quality of its habitat in the in the mountains of Cameroon and Nigeria (Amiet and Gartshore, 2004).
It occurs in the Cross River National Park in Nigeria. There is a need for improved habitat protection of montane forest habitats in Cameroon (Amiet and Gartshore, 2004).
Although it is somewhat adaptable, it is probably affected by agricultural expansion, logging, and human settlements when these lead to serious opening up of the habitat (Amiet and Gartshore, 2004).
Populations of this species are decreasing (Amiet and Gartshore, 2004).
This species is easily differentiated from other Cameroonian and Nigerian species by the distinct bullseye ventral pattern, and 4-5 additional tarsal tubercles (1 present in most species) with the last one forming a small, pointed spur on the heel.
Mitochodrial sequence data from 12S rRNA, valine-tRNA, and 16S rRNA fragment support a sister relationship between P. cricogaster and P. steindachneri (Zimkus, 2009). Mitochodrial sequence data from the same mtDNA genes, as well as combined sequence data from mitochondrial and nuclear (RAG-1) genes also support the sister relationship between P. cricogaster and P. steindachneri (ZImkus et al, 2010).
This species is one of the few puddle frogs that can be easily identified due to it's distinct bullseye ventral pattern.
Aspect is raniform with a moderately slim body. A conical papilla is present in the middle of tongue that is notched at its distal end. Snout is blunt, the same length as the orbit and exceeding the jaw lower by approximately 1 mm. Cathus rostralis is not marked. Loreal region is slightly but definitely concave. Head is slightly more broad than long. Tympanum is distinct and half of the horizontal diameter of the eye. Fingers are blunt and hardly dilated in disc. Sub-articular tubercles are average. Manual webbing is absent. Inner metatarsal tubercle is ovoid, measuring approximately one the third of the length of toe I. A conical tarsal tubercle is present on the same side as the inner metatarsal tubercle, approximately in the middle of the tarsus. An external metatarsal tubercle is followed by three to four additional tarsal tubercles, distributed along the length of the tarsus. A small, pointed spur is present on the heel, approximately twice the size of the other tarsal tubercles and measuring approximately 1 mm in height. Toes are slightly but definitely dilated in discs. The tibio-tarsal articulation reaches the middle of the eye. Tibia measure 11-13 mm in males and 17-18 mm in females (N=54; Perret, 1966). Toes are 3/4 webbed with 2.5-3 phalanges free on toe IV (Perret, 1966). Zimkus (unpub.) found that pedal webbing was more variable with 1-3 phalanges free on toe IV. Skin is finely granular on the dorsum, lateral sides and top of the limbs, more coarsely granular on the head and eyelids. Two prominent V-shaped scapular glands are present, and a pair of smaller folds is present behind the most prominent glands, approximately three quarters down the back. Other less prominent folds are present on the sides of the body and the limbs. Ventral side, including limbs, is smooth. Prominent nuptial pads on manual digit I are present in males. A subgular sac without localized folds is present in males; slits measure 1 mm in length (Perret, 1966).
Dorsum is brown-black, uniform or with some large brown-red scapular spots. Hind limbs barred with brown red; half-bars present in the middle of the thighs and three bars on the tibiae. Venter is cream. Throat is grey with a cream-coloured median spot near the chest; gular coloration can be very dark in the males. Belly is decorated with a small central dark circle, which can be either white or dark in the center, and surrounded by a complete or incomplete concentric circle that abuts the chest and groin.
According to Perret (1959, 1966), the SVL of males range from 20-23 mm, while females range from 30-32 mm (N=54). The male holotype measures 23.5 mm (Perret, 1957).
A group identified by Zimkus (2009) that includes P. cricogaster is endemic to the mountains of western Cameroon and eastern Nigeria, part of the geologic rift zone termed the Cameroon Volcanic Line, and supports the view that montane regions have acted as centres of speciation.
This species is restricted to the mountains of eastern Nigeria and western Cameroon. There are records from the Obudu Plateau and the higher parts of the Oban Hills in Nigeria, and from the Rumpi Hills, Mount Kupe, Mount Manenguba, Mount Nlonako, and the Bamileke plateau (Petit Diboum, Mount Bana, Fotabong an Foto) in Cameroon but has not been found as far north as Mount Oku (Perret, 1957, 1966; Hofer et al., 1999; Amiet and Gartshore, 2004).
It lives in submontane and montane primary and secondary forest, degraded forest, and dense brush from 850-1,850m asl. It does not appear to survive in completely open habitats (Amiet and Gartshore, 2004).
It is abundant at 1,400m asl on Mount Manenguba, but rare at 1,000m asl on Mount Nlonako (Amiet and Gartshore, 2004).
It breeds in still pools along mountain streams (Amiet and Gartshore, 2004).