Ptychadena anchietae (Bocage, 1868)
Original Published Description:
Plain Grass Frog (English), Northern Rana (English), Benguella Grassland Frog (English), Anchieta's Frog (English), Anchieta's Ridged Frog (English), Savanna Ridged Frog
Ptychadena anchietae is a medium-sized frog (snout-vent length approximately 5 cm) with a pointed nose and a characteristic color pattern with black mask-like stripes present on the face, dark spots on the flanks and a brown and yellow marbled pattern on the backs of the thighs. The back is grayish olive brown, and the underside is white or yellowish white. It is found in a variety of habitats, including forest, savanna, shrubland, wetland, desert, and pond ecosystems.
This species ranges from Eritrea, Ethiopia, Djibouti and Somalia, south through East Africa to South Africa and Botswana, and west to Angola and southern Republic of the Congo. There do not appear to be confirmed records from Burundi and Rwanda, though it is likely to occur in these countries (Poynton et al., 2004).
P. anchietae occurs in savanna habitat in all sub-Saharan countries from Angola to Ethiopia in the north, southward to eastern Namibia (Caprivi), eastern Botswana, Zimbabwe and Mozambique (Poynton and Broadley 1985b). This species is found in South Africa, Lesotho, and Swaziland (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
The specific epithet “anchietae” refers to the Portuguese naturalist José Alberto de Oliveira Anchieta, who sent several specimens of this species to Bocage who first described it.
This is a medium-sized frog with long legs. The dorsum is uniform brown with around 7 rows of parallel
ridges. Some individuals have darker blotches scattered over the dorsum. Middorsal and tibial stripes are never present. A distinct pale triangle covers the area of the snout in front of the eyes. The tympanum is clearly visible and edged in white. The toes are nearly fully webbed, with only the tip of the fourth toe free of webbing (Text from Harper et al., 2010).
Males are up to 51 mm in snout-vent length, and females are up to 62 mm (Harper et al., 2010). A male from the type series had a snout-vent length of 48 mm, with the forelimb 28 mm long and the hindlimb 86 mm (Bocage, 1868).
The following is the original description by Bocage (1868).
The head is wide, with a long pointed snout. The nostrils are slightly closer to the tip of the snout than to the eye. The tympanum has almost 2/3 the diameter of the eye. There are two small series of vomerine teeth, situated precisely in front of the hind openings of the nostrils and separated by a substantial interval. On the forelimbs, the second and fourth digits are equal in length, with the third the largest. The toes are webbed up to the base of the last phalange, except on the fourth toe where the last two phalanges are free. The metatarsal bears a single tubercle on its internal edge. Four narrow and distinctly granular longitudinal folds of skin are present on each side of the back. The top of the head and the space between the dorsal folds are dotted with small tubercles; larger confluent tubercles cover the flanks, the cloacal area, and the posterior half of the underside of the thigh. The skin is smooth ventrally with no trace of granulations or pores.
The dorsal regions are grayish or olive in color, marbled or spotted more or less distinctly with brown. Darker brown transversal bands mark the external sides of the limbs. A small blackish line extends from the tip of the snout to the eye via the nostril; an elongated spot of the same color extends from the eye to the shoulder via the dorsal side of the tympanum. The posterior side of the thighs is reddish brown to chocolate brown, with small, round yellow spots or narrow, wavy yellow stripes. Ventral parts are white or yellowish-white. On some individuals, the undersides of the thighs are bright yellow.
P. anchiete can be distinguished from other members of the genus by the pale triangle on the snout, horizontal stripes on the backs of the thighs, and extensive toe webbing with only the last joint of the longest toe free of webbing (Text from Harper et al., 2010).
Habitat and Ecology
Ptychadena anchietae is a species of open country in woodland, savannah, grassland, and agricultural and suburban areas, but also found in forest clearings. It is usually (but not always) found in close proximity to permanent water. This species occurs up to 1,800 m asl in Ethiopia (Poynton et al., 2004).
P. anchietae is a widespread inhabitant of the savanna biome in the northeastern part of the atlas region, between 20 and 1450 m a.s.l. It occurs in relatively moist, coastal bushveld vegetation types with a minimum annual rainfall in excess of 600 mm, as well as in more arid habitats such as Mixed Bushveld, which experiences a minimum annual rainfall of 350 mm (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
This ridged frog is found in much the same kinds of places as the Mascarene ridged frog. However, this frog appears to prefer the lowland areas, whereas the Mascarene ridged frog occurs in greater numbers within the mountains (Text from Measey et al. 2009, © SANBI).
This frog inhabits open areas in lowland savannas, grasslands and woodlands and is typically found near water. It tolerates some habitat modification and may be found in former forest, agricultural and suburban areas (Harper et al., 2010).
This species is abundant in many parts of its range (Poynton et al., 2004).
Populations of this species are stable (Poynton et al., 2004).
Ptychadena anchietae tested positive for Batrachochytrium dendrobatidis in Nairobi, Kenya in 2000 (Berger & Speare 2000). Also tested tested positive for B. dendrobatidis in Kihansi Gorge, Tanzania in 2003 (Weldon & Du Preez 2004).
Chytrid fungus was detected in this species in Kenya (Poynton et al., 2004).
Barbour and Loveridge (1928) record the diet to include grasshoppers, crickets, beetles and other insects (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
This species is also a friend to Taita farmers as during the day it eats small invertebrates which may damage crops (Text from Measey et al. 2009, © SANBI).
Breeding choruses develop after the first spring rains, through to late summer or autumn (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
This ridged frog breeds during all but the driest months (June to September) and in the same places as the Mascarene ridged frog; in ponds, pools and puddles at the side of the road (Text from Measey et al. 2009, © SANBI).
It breeds in shallow temporary ponds (Poynton et al., 2004). Small eggs, gray on top and white below, are laid in a single layer that floats on the surface of the water (Harper et al., 2010).
In late winter to early spring, adults begin to congregate around permanent water bodies. At this time, vocalization is restricted to infrequent, quiet, low trills, which differ from the advertisement call. Passmore (1978) found that males call from bare or sparsely vegetated areas of the shoreline, usually within 20 cm of the water’s edge. The average distance between calling males is about 80 cm; a distance of less than 20 cm usually elicits a territorial call that results in one of the males moving away from the other (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
The calls that the males produce come from the same kinds of lateral vocal sacs either side of the head. The call they produce sounds very different and can help you identify them as it sounds like a ‘wah wah wah’ (Text from Measey et al. 2009, © SANBI).
Males call near the edge of temporary pools and flooded grasslands. The call is a rapid high-pitched trill repeated three times every two seconds (Harper et al., 2010).
The tadpoles break out of the jelly capsule after 24 hours and develop rapidly (Stewart 1967), undergoing metamorphosis and leaving the water three weeks later (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
Tadpoles are brown above and light below with a clear fin and may reach 45 mm in length (Text from Harper et al., 2010).
Modes and Mechanisms of Locomotion
This frog is a keen jumper that will catapolt as soon as it is disturbed. If it reach the water on the first jump, it will either jump again, or disappear into the bottom of the grass (Measey et al. 2009, © SANBI).
IUCN Red List Category and Justification of Conservation Status
The IUCN Red List (2004) categorizes this species as Least Concern in view of its very wide distribution, its tolerance of a broad range of habitats, its presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category (Poynton et al., 2004).
P. anchietae does not appear to be at risk as much of its habitat is used for game and cattle farming and is relatively undisturbed. The species occurs in a number of provincial nature reserves and national parks (Text from Minter et al., 2004, © SI/MAB Biodiversity Program).
Ptychadena anchietae is an adaptable species that is only likely to be facing localized threats. Chytrid fungus was detected in this species in Kenya (Poynton et al., 2004).
Conservation Actions and Management
This species occurs in many protected areas (Poynton et al., 2004).
- Rana anchietae Bocage, 1868 "1867" (synonym)
- Rana abyssinica Peters, 1881 (synonym)
- Rana gondokorensis Werner, 1908 "1907" (synonym)
- Rana aberae Ahl, 1925 "1923" (synonym)
- Rana oxyrhynchus migiurtina Scortecci, 1933 (synonym)
- Ptychadena abyssinica — Guibé and Lamotte, 1961 "1960" (synonym)
- Rana (Ptychadena) abyssinica — Pienaar, 1963 (synonym)
- Ptychadena anchietae — Poynton, 1964 (synonym)
- Ptychadena (Ptychadena) anchietae — Dubois, 1992 (synonym)