Amietia moyerorum
Moyer's River Frog
family: Pyxicephalidae
subfamily: Cacosterninae
Species Description: Channing A, Dehling JM, Loetters S, Ernst R 2016 Species boundaries and taxonomy of the African river frogs (Amphibia: Pyxicephalidae: Amietia). Zootaxa 4155: 1-76.

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Conservation Status (definitions)
IUCN (Red List) Status
Other International Status None
National Status None
Regional Status None


The male Ameitia moyerorum has a snout-urostyle length of 61 - 67 mm. No female specimens have been described. The male specimens are rather stocky, being widest at mid-body. The head is about as wide as it is long and not wider than the trunk. The snout is long and appears bluntly rounded when viewed dorsally, but sharply rounded in profile. The snout projects beyond the lower jaw and is about as long as it is wide. The canthal ridge is indistinct and uniformly rounded, almost creating a straight line from the eye to just beyond the nostril. The loreal region is slightly concave in shape and almost vertical. The nostrils are raised and rimmed, with a single outer flap and a small, antero-dorsally directed knob-like protuberance. The nostrils are located much closer to the eyes than the tip of the snout and are separated by a distance equal to the distance from the eye. The moderately sized eyes protrude beyond the jawline and are directed antero-laterally. The distance between the eyes is less than both the width of the eyes themselves and the distance between the nostrils. The rounded tympanum is very visible, smaller than the eye and located close to the eyes. The supratympanic fold is very visible and it runs from the back edge of the eye to the angle of the jaw. There is a single vocal sac located on the lower part of the throat that appears white when fully inflated (Channing et al. 2016).

There are tiny, low, white-tipped spine-like tubercles evenly and densely scattered on the dorsal surfaces of the head, trunk, hind limbs and to a lesser extent, the forearms. The ventral surfaces of the limbs and lower throat are smooth. The forelimbs of A. moyerorum are robust and have moderately large hands, on which the fingers have rounded tips without disks. The relative lengths of the fingers are I < II < IV < III. There is one rounded, well-developed subarticular tubercle on fingers I and II and two on fingers III and IV. There are no supernumerary tubercles present but there is a thenar tubercle that is obscured by the nuptial pad, as well as two palmar tubercles. Nuptial pads are present on the first and second fingers, being well developed and covering the proximal dorsal and ventral surfaces of finger I extending to the tubercle, and the dorsal surface of the penultimate phalanx of finger II. The hind limbs are also robust and they have a long tibia that is over half the length of the body and equal to the length of the foot. The heels overlap when the knees are flexed and thighs are held laterally at a right angle to the body. The relative lengths of the toes are I < II < III < V < IV. There is one subarticular tubercle on toes I and II, two on each of III and V, and three on toe IV. The pedal webbing formula is I1-2II0-2III1-2IV2-0V. The thin webbing extends to the last phalanx of each toe. There is no outer metatarsal tubercle but the inner metatarsal tubercle is narrow and prominent (Channing et al. 2016).

In stage 37, one tadpole is described as having a length of 91.8 mm for the total length and the tail is 2.4 times the length of the robust body. The eyes are positioned high on the head with a small pineal spot between the anterior edges, and there is no umbraculum present. The oval-shaped nostrils are close together and have rimmed margins. There are no visible lateral lines. The wide and flattened spiracle has an opening against the body and is located below the level of the eye. The base of the dorsal fin originates from the notably muscular tail. The fins are positioned low on the body and have an acute tip. Younger tadpoles have fewer tooth rows but a labial tooth row formula of 5(2-5)/3(1) is frequently observed. There is a single, uniformly sized row of posterior marginal papillae separated by an anterior gap the width of the oral disk, along with additional papillae in the angle of the mouth (Channing et al. 2016).

Molecular data and overall morphology of A. moyerorum place the species firmly within the Amietia clade. Amietia moyerorum’s sister species is A. nutti, and it is sympatric with A. tenuoplicata from southern Tanzania and northern Malawi. The advertisement call of A. moyerorum can be differentiated from that of A. tenuoplicata through the number of phase clicks, of which there are 9 - 14 in A. moyerorum and 22 - 28 in A. tenuoplicata. In A. moyerorum the clicks are double and the second phase croak is not frequency-modulated, but the clicks are single and the croaks are strongly frequency-moderated in both A. nutti and A. tenuoplicata. Physically, A. moyerorum differs from A. nutti and A. tenuoplicata in the width of the pale areas between the dark transverse femur bans in relation to the width of the bands themselves, which is double in A. moyerorum but equal to or less than in A. nutti and A. tenuoplicata. In A. moyerorum, only one phalanyx on the fourth toe is usually free of webbing on the outside, but in A. nutti, two phalanges are free. The largest specimen of A. moyerorum (92.4 mm) occurs within the range of largest specimens for A. nutti (87.8 mm) and A. tenuoplicata (92.5 mm). Geographically, A. moyerorum occurs in southern Tanzania and northern Malawi, whereas A. nutti is widespread throughout Ethiopia, through the eastern Democratic Republic of Congo to southern Tanzania and A. tenuoplicata is found from the Taita Hills in Kenya to the southern highlands of Tanzania (Channing et al. 2016).

The tadpole labial tooth row formula for A. moyerorum (5(2-5)/3(1)) differentiates it from A. nutti, which has a labial tooth row formula of (4(2-4)/3(1)) (Channing et al. 2016).

In life, the dorsum has a more or less symmetrically arranged pattern of dark blotches lined in black, on a dark brown background. The snout is unmarked but there is a pale band that extends between the eyes. The upper lip is mottled but the lower lip has marbling in dark brown and white. There is a pale coppery band that runs from the side of the snout to the rictal gland, becoming thinner and white as it progresses. There is also a thin line that extends up to the back edge of the eye. The tympanum and the area around it are dark in color. There are also tiny, low, white-tipped spine-like tubercles evenly and densely scattered on the dorsal surfaces of the head, trunk, hind limbs and to a lesser extent, the forearms. The ventral surface and flanks are pale to white, but the ventral surface remains unmarked while there are dark blotches on the flank and marbling on the throat, extending to the chest. The vocal sac is white. The distal phalanges of the fingers are lightly pigmented with the color extending along the outer surface of the forearm until it merges with the dorsal pigment. The plantar side of the foot is dark but the tubercles are pale (Channing et al. 2016).

In the stage 37 tadpole, the body, tail and dorsal fin are speckled and mottles but the ventral fin is clear. This species has dark nasal capsules (Channing et al. 2016).

No vertebral stripe was observed in the paratypes, but they were all similar in proportions and webbing (Channing et al. 2016).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Malawi, Tanzania, United Republic of

View distribution map using BerkeleyMapper.
Amietia moyerorum was originally found at an elevation of 1900 m in the Itimba stream Mumba, within the Rukwa District of Tanzania. The location coordinates are 08° 10’ 44.9” S; 31° 51’ 47.8”E. Its distribution is known to range from the Nyika Plateau in Malawi, north through Mbeya, the Rukwa Valley to Mumba, Mt. Rungwe and the Udzungwa Mountains as far as Kisolanza in Tanzania at elevations between 800 - 1400 m. It is likely more widespread (Channing et al. 2016).

Life History, Abundance, Activity, and Special Behaviors
The advertisement calls of three males were recorded at an air temperature of 24°C. The calls consist of two phases, separated by a long pause of 1.2 s. The first phase was a series of 9 - 14 evenly spaced double clicks and the second phase had 32 - 46 pulses at a mean rate of 80 s-1 for 0.5 - 0.9 s. The fundamental frequency of the apparent harmonics in the second phase was 410 Hz. The third harmonic of 1640 Hz was emphasized in particular. When two frogs called in unison, they were arranged so that the call of the second frog overlapped the pause between the two phases of the call from the first frog (Channing et al. 2016).

The species authority is: Channing, A., Dehling, J.M., Lötters, S., and Ernst, R. (2016). ''Species boundaries and taxonomy of the African river frog (Amphibia: Pyxicephalidae: Amietia).'' Zootaxa, 4155(1), 1-76.

Using Bayesian Inference and Maximum Likelihood analysis on mitochondrial 12S (450 base pairs) gene and nuclear genes 28S (720 base pairs), histone (300 base pairs) and tyr (530 base pairs) from 122 specimens, Amietia moyerorum was found to be most closely related to Amietia nutti. However, when mitochondrial 16S (550 base pairs) genes from 323 specimens were analyzed using Bayesian Inference and Maximum Likelihood analysis, A. moyerorum shows the closest phylogenetic relationship to A. tenuoplicata. Amietia moyerorum is most likely a sister species to A. nutti, which together form a clade with A. tenuoplicata (Channing et al. 2016).

The species name “moyerorum” originates from the last name of Carl and Joanne Moyer, who dedicated over 40 years to supporting local communities in the region where Amietia moyerorum is found. They also contributed to the Ameitia project (Channing et al. 2016).


Channing, A., Dehling, J.M., Lötters, S., and Ernst, R. (2016). ''Species boundaries and taxonomy of the African river frog (Amphibia: Pyxicephalidae: Amietia).'' Zootaxa, 4155(1), 1-76.

Written by Krystal Austin (kaustin AT, UC Berkeley
First submitted 2016-10-25
Edited by Ann T. Chang (2016-11-03)

Species Account Citation: AmphibiaWeb 2016 Amietia moyerorum: Moyer's River Frog <> University of California, Berkeley, CA, USA. Accessed Jan 23, 2017.

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Citation: AmphibiaWeb. 2017. <> University of California, Berkeley, CA, USA. Accessed 23 Jan 2017.

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