Mascarene Ridged Frog
Ptychadena mascareniensisSummary 1
The Mascarene Grass Frog or Mascarene Ridged Frog (Ptychadena mascareniensis) is a species of frog in the Ptychadenidae family.
Description 2
A big, long-legged ranid with a pointed snout and distinct dorsal ridges. SVL of males: 43–57 mm; females: 43–68 (–72?) mm. The large clearly visible tympanum reaches 0.7–0.9 of the eye diameter. Two pairs of continuous dorsal ridges. A short ridge between the outer dorsal ridge and the dorsolateral one. Occasionally this ridge may be absent. Some larger warts on the flanks. Males with paired lateral vocal sacs whose slits run from the end of the lower jaw directly to the base of the arm. Thigh length is 0.45–0.62 of the SVL; the lower leg measures 0.58–0.65, and the foot, incl. longest toe, reaches 0.73–1 of the SVL. Fingertips and toe-tips not expanded. The inner metatarsal tubercle is tiny, reaching just 0.2–0.4 of the shortest toe length. Webbing formula: 1 (0.5) or (1), 2 i/e (1–0.5) or (1.5–0.5), 3 i/e (1.5–0.5) or (1–0.5), 4 i/e (2) or (1) or (0.5), 5 (0.25) or (0.5) or (1). The ventral skin is granulated. The legs of larger individuals are proportionally longer (Guibé & Lamotte 1958a). Patterson & McLachlan (1989) give a median adult SVL of 40.5 mm.
Coloration: The back has a uniform brown basic coloration with a bright vertebral band beginning at the snout tip. The color of this band may be white, beige, yellow, orange or green. Some individuals may lack this band. Several black spots are present on the dorsal ridges. The dorsolateral ridges are light. Animals showing a uniform dark coloration with a fine pale vertebral line are reported to exist, too. The brown tympanum has a narrow pale border and a somewhat paler center. It is surrounded by a dark temporal triangle. The region between nostril and eye is also dark. The vocal sacs are gray. Several white patches occasionally appear on the flanks. The dark bars on the thighs are present only on the anterior part. A thin yellow longitudinal line with black borders runs along the posterior part of the thighs. The light brown shanks invariably show a narrow light longitudinal line. A similar marking may appear on the thighs. The upper lip is bright white, and this coloration is likewise present on the infratympanic ridge stretching to the upper arm. If black bars are present on the shanks, they are usually restricted to the posterior part. Black spots are present on the ventral border of the lower jaw. The throat may be mottled black. The rest of the venter is white to yellowish. The ventral parts of the extremities are white-orange.
Voice: Amiet (1974b) describes the advertisement call as a low nasal "hoin". It resembles the call of P. bibroni, but seems to be lower and "slower". Lambiris (1989) describes a short and very nasal "quack" usually followed by several click sounds. A sonagram has been published by Schiøtz (1964c), too. According to Perret (1979b), the calls of frogs from South, East and West Africa are identical. The call of Serengeti frogs described by Van Den Elzen & Kreulen (1979) consists of 12 pulses (Amiet/Cameroon: 22) per call and lasts about 0.12 sec (Amiet: 0.15–0.2 sec). The dominant frequencies in Tanzanian frogs are 0.5–1.2 kHz and 2.3–3 kHz (Amiet; 1.3–2.3 kHz). According to Passmore (1977), the call of South African frogs comprises 16 pulses and lasts 0.17 sec (dominant frequency: 2.3–3 kHz). The differences might be, at least partially, temperature-dependent. Akef & Schneider (1995) described the advertisement call in Egyptian P. mascareniensis. Their frequency range was 0.25–3.5 kHz. The calls were uttered in long continuous series from 5–10 min. Variation in some calling parameters was temperature dependant.
Similar species: Easily distinguished from Hoplobatrachus tigerinus by the more continuous dorsal folds rather than rows of tubercles.
This account was taken from Rödel, M.-O. (2000), Herpetofauna of West Africa vol. I. Amphibians of the West African Savanna, with kind permission from Edition Chimaira publishers, Frankfurt am Main.
Also taken with permission from Vences and Glaw (2007).
Sources and Credits
- (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Ptychadena_mascareniensis
- (c) AmphibiaWeb © 2000-2015 The Regents of the University of California, some rights reserved (CC BY), http://eol.org/data_objects/34271926
