Ptychadena amharensis Smith, Noonan & Colston, 2017

Goutte, Sandra, Reyes-Velasco *, Jacobo, Freilich, Xenia, Kassie, Abeje & Boissinot, Stephane, 2021, Taxonomic revision of grass frogs (Ptychadenidae, Ptychadena) endemic to the Ethiopian highlands, ZooKeys 1016, pp. 77-141 : 77

Ptychadena amharensis Smith, Noonan & Colston, 2017

Type material.

Holotype. by original designation. A juvenile (XF140) collected on 18 July 2011 by X. Freilich and S. Boissinot in Dejen, Amhara region, Ethiopia (10.1908°N, 38.140°E, 2425 m a.s.l.). Paratypes. Three adult females (XF141, XF142, XF143) collected by X. Freilich and S. Boissinot on the same date and location. All type specimens and material examined are deposited at ZNHM.

Material examined.

In addition to the type series, we examined one male (15-313) collected on 17 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot southeast of Debre Markos (10.2745°N, 37.8564°E, 2261 m a.s.l.), one female (15-367) collected on 19 August 2015 by X. Freilich J. Reyes-Velasco and S. Boissinot southwest of Debarq (13.0359°N, 37.799°E, 2583 m a.s.l.), one female (16-175) collected on 15 July 2016 by X. Freilich, J. Reyes-Velasco and S. Boissinot in Debre Markos (10.35195°N, 37.7414°E, 2803 m a.s.l.), one female (SB580) collected on 8 July 2018 by S. Goutte and Y. Bourgeois north-west of Debre Markos (10.3566°N, 37.6571°E, 2589 m a.s.l.), one female (SB584) collected on 8 July 2018 by S. Goutte and Y. Bourgeois in Debre Markos (10.35195°N, 37.7414°E, 2388 m a.s.l.) and five males (SB591, SB592, SB593, SB597 and SB606) collected on 9 July 2018 by S. Goutte and Y. Bourgeois in Debre Markos (10.3520°N, 37.7414°E, 2388 m a.s.l.).

Diagnosis.

Medium-sized species (male (6) SVL 36.9 ± 2.7 mm, female (7) SVL 42.5 ± 2.0 mm) of the Ptychadena cooperi species group (Fig. 9 ). It differs from other members of the Ptychadena neumanni species complex by the following combination of characters: (1) tibia half of the snout-vent length, (2) eye close to one another (male IOD/HW 0.16 ± 0.02, female IOD/HW 0.17 ± 0.02), (3) vertical light stripe on the tympanum, (4) vocal sacs are light grey to cream, sometimes mottled with light grey, (5) adult males’ bodies covered in small warts.

Comparison.

Ptychadena amharensis is smaller than P. cooperi and larger than P. nana and P. robeensis sp. nov. It has shorter hindlimbs than P. doro sp. nov., P. neumanni , P. goweri , and P. harenna . Ptychadena amharensis has a shorter head than P. beka sp. nov., P. neumanni , P. harenna and P. goweri . The species’ interorbital distance is shorter than in P. doro sp. nov., P. delphina sp. nov., P. erlangeri , P. levenorum , P. goweri , P. nana , P. neumanni , and P. robeensis sp. nov.

Description of the holotype.

Juvenile, in poor condition (Fig. 10 ). Right hind limb missing. No visible ridges or coloration on the back due to the poor condition of the specimen. Finger formula: 1<2<4<3, hand free of webbing. Toe formula: 1<2<5<3<4. Toe webbing indistinguishable. Tongue bifurcated and free for half is length. Maxillary and premaxillary teeth present, vomerine teeth not visible. Throat cream.

Measurements of the holotype (mm): SVL 21.4, HW 8.8, HL 9.3, SL 3.7, NS 2.1, IND 2.1, EN 1.8, IOD 1.6, ETD 0.9, TD 1.6, ED 2, UEW 1.1, FLL 3.9, HAL 4.9, F4DW 0.3, THL 9.6, TL 9.7, FL 10.1, T4DW 0.3, MTL 0.9.

Coloration of the holotype in preservative.

Dorsal background color is grey, with almost completely faded away dark grey markings in between the eyes and on the upper part of the dorsum. Dark brown canthal stripe from the tip of the snout to the back of the jaw. No vertical stripe or blotch on the tympanum. Upper lip, throat, and posterior part of flanks cream. Irregular dark brown markings on the anterior third of the flanks. Ventrum, ventral side of the thighs and tibias uniformly cream. Faint dark brown bars on the tibia. Thighs posteriorly dark brown with large cream spots.

Variations.

In life, background coloration varies from dark orange to light olive or yellowish brown. Small, more or less distinct, dark brown blotches distributed on the dorsal ridges and on the antero-dorsal part of the flanks. Cream or sand-colored thin or wide vertebral stripe present in all examined specimens.

Iris bicolored, with the upper third silver to sand color, and the lower two thirds brown or copper to dark brown. Upper and lower jaws with light brown irregular markings. Dark brown canthal stripe from the tip of the snout to the back of the upper jaw. More or less distinct cream-colored vertical stripe or blotch on the tympanum. Light thin stripe on the tibia, extending over the lower third of the thigh. Back thighs light yellowish grey to greenish yellow reticulated with dark grey. Ventrum white to light yellow, throat white to bright yellow. Vocal sacs cream or light grey sometimes molted with light grey. Dorsum and hindlimbs of adult males covered in small warts.

Habitat, distribution, and natural history.

Ptychadena amharensis is found in the Amhara plateau, at elevations ranging from 1824 m to 2642 m a.s.l. This species is found notably around Debre Markos, Enjebara, Bahar Dar and Gondar. The northern-most individuals were found just south of Debarq (13.1098°N, 37.8637°E), while the southernmost individuals were found around Dejen (10.1908°N, 38.1401°E), just North of the Blue Nile. This species has not been found south of the Blue Nile.

Males are found calling at night from flooded grass fields, sometimes aggregating in important numbers, in sympatry with Ptychadena wadei and Ptychadena pumilio south of Bahar Dar.

Advertisement call.

Ptychadena amharensis males produce calls (4 males, 47 calls) of 355 ± 276 ms duration, containing 4 ± 3.5 pulsed notes. Each note is 43 ± 15 ms in duration and pulses are indistinct. Call rate is highly dependent of the social context as P. amharensis tends to call in large choruses and their motivation to call is linked to the number of acoustically active conspecific males in their direct surroundings. Call dominant frequency is 2224 ± 158 Hz. Notes are frequency modulated, with an increase in dominant frequency within each note.

Within the P. neumanni complex, the call of P. amharensis can be distinguished from those of P. erlangeri , P. levenorum , P. nana , P. robeensis sp. nov., P. beka sp. nov., P. delphina sp. nov., P. goweri , and P. neumanni call type 2 by the indistinct pulses of its notes. It is distinct from P. doro sp. nov. by having calls composed of multiple notes, a higher dominant frequency and wider frequency bandwidth. The call of P. amharensis is distinguishable from P. neumanni call type 1 by having frequency-modulated notes and note groups and longer notes. The call of P. amharensis resemble most the call of its closely related P. cooperi , although with a higher peak frequency, reflective of the smaller size of the species, and notes grouped within each call while the notes of P. cooperi calls are regularly spaced.

Remarks.

Neither the holotype designated by Smith et al. (2017), which is a juvenile in poor condition with one missing leg, nor the diagnosis provided in the original description provide characters allowing the distinction between P. amharensis and other species of the P. neumanni complex. The SVL values given for males and females in Smith et al. (2017a, b) do not correspond to measurements taken on the type series (holotype: juvenile SVL 21.8 mm, paratypes: adult females, SVL 40.2, 43.3, 43.8 mm) and were taken from a summary table (table 4 in Freilich et al. 2014) with no acknowledgement of the original data, and specimens of the type series have evidently not been examined by the authors. The altitudinal range for the species was taken from the same table, but values were rounded in Smith et al. (2017a, b).

Figures

Figure 9. Ptychadena amharensis A live male (SB 593; left) and female (SB 580, right) B dorsal and ventral views of the same individuals (male left, female right) after euthanasia and before fixation.

Figure 10. Type specimens of Ptychadena amharensis A dorsal and ventral views of the juvenile holotype (XF 140) B dorsal and ventral views of one of the three adult female paratypes (XF 141).