Leptopelis shebellensis Goutte, Reyes-Velasco, Kassie & Boissinot, 2022

Goutte, Sandra, Reyes-Velasco, Jacobo, Kassie, Abeje & Boissinot, Stephane, 2022, Genetic and morphometric analyses of historical type specimens clarify the taxonomy of the Ethiopian Leptopelis gramineus species complex (Anura, Arthroleptidae), ZooKeys 1128, pp. 63-97 : 63

Leptopelis shebellensis Goutte, Reyes-Velasco, Kassie & Boissinot sp. nov.

Common name.

English: Shebelle River burrowing African treefrog.

Type material.

Holotype. Adult male (SB482), collected on 26 June 2018 by S. Goutte and Y. Bourgeois near the town of Ch’ange, Oromia, Ethiopia (8.1263°N, 39.4360°E, 2429 m a.s.l.). Paratypes. One male (15-46), collected on 5 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot, south of Assela (7.9068°N, 39.1238°E, 2520 m a.s.l.), one male (15-79) and one female (15-83), collected on 6 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot, southwest of Dinsho (7.1156°N, 39.7390°E, 3029 m a.s.l.), one male (15-84), collected on 6 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot southwest of Dinsho (7.1105°N, 39.7461°E, 3042 m a.s.l.), one male (15-143), collected on 8 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot between Robe and Ali (7.1720°N, 39.9722°E, 2431 m a.s.l.), one female (15-152), collected on 8 August 2015 by X. Freilich, J. Reyes-Velasco and S. Boissinot in Goba (7.0110°N, 39.9677°E, 2699 m a.s.l.), two females (16-8, 16-9), collected on 5 July 2016 by J. Reyes-Velasco and S. Boissinot south of Assela (7.8656°N, 39.1305°E, 2605 m a.s.l.), one females (16-25), collected on 6 July 2016 by J. Reyes-Velasco and S. Boissinot south of Assela (7.8836°N, 39.1245°E, 2531 m a.s.l.), two males (16-26, 16-28), collected on 6 July 2016 by J. Reyes-Velasco and S. Boissinot north of Bekoji (7.5585°N, 39.2520°E, 2721 m a.s.l.), one male (16-88), collected on 10 July 2016 by J. Reyes-Velasco and S. Boissinot east of Dinsho (7.1065°N, 39.8184°E, 3065 m a.s.l.), one male (16-93), collected on 10 July 2016 by J. Reyes-Velasco and S. Boissinot west of Dinsho (7.1204°N, 39.7358°E, 3048 m a.s.l.), three males (SB61, SB62, SB63), collected on 26 June 2018 by S. Goutte and J. Reyes-Velasco south of Dinsho (7.0915°N, 39.7834°E, 3079 m a.s.l.), two males (SB483, SB484), collected on 26 June 2018 by S. Goutte and Y. Bourgeois near Ch’ange (8.1263°N, 39.4360°E, 2429 m a.s.l.), three males (SB502, SB504, SB505), collected on 28 June 2018 by S. Goutte and Y. Bourgeois north of Arussi Robe (7.9190°N, 39.6091°E, 2433 m a.s.l.).

Diagnosis.

Medium to large (male (n = 21) SVL 35.9 ± 3.5 mm, female (n = 5) SVL 53.4 ± 5.3 mm), robust semi-fossorial species of the Leptopelis gramineus species complex (Fig. 7 ). It differs from other members of the Leptopelis gramineus species complex by the following combination of characters: (1) short and robust hind-limbs (male TL/SVL 0.33 ± 0.03, female TL/SVL 0.30 ± 0.02), (2) well-developed metatarsal tubercle (male MTL/FL 0.17 ± 0.03, female MTL/FL 0.16 ± 0.02), (3) longer snout (male SL/HL 0.23 ± 0.03, female SL/HL 0.24 ± 0.02), (4) toe and fingertips not enlarged and (5) ventrum often with dark brown spots and/or yellowish sides.

Comparison.

Larger body size, longer head and snout and greater snout-nostril distance and larger tympanum and metatarsal tubercle than L. gramineus , L. diffidens and L. sp. Kibre Mengist (Table 1 , Suppl. material 5: table S9). Shorter hind-limbs and smaller finger and toe discs than L. rugosus and L. susanae (Table 1 , Suppl. material 5: table S9).

Description of the holotype.

Medium size adult male (SVL 40.6 mm). Body robust (Fig. 7 ). Head a third of body size in length, wider than long (HW/HL 1.14). Snout wide (IND/IOD 0.87). Nostrils closer to the tip of the snout than the eyes (NS/SL 0.47). Canthus rostralis well-marked, but obtuse and loreal region slightly concave. Pupil vertical. Tympanum partially hidden on the posterior-dorsal edge, 0.40 × eye diameter.

Fingers and toes robust with ovoid discs not expanded, but distinct. Finger formula: I <II <IV <III. Hand free of webbing. Hind-limbs short and robust (TL/SVL 0.31 and THL/SVL 0.38). Foot 1.32 × tibia length. Inner metatarsal tubercle present, oval in shape, 0.16 × foot length. Outer metatarsal tubercle absent. Toe formula: I <II <III <V <IV. Foot webbing minimal, except between toe III and toe IV where webbing extends to half-way between the first and the second phalanges. Skin of the dorsum, flanks and ventrum slightly rugose.

Colouration of the holotype in life.

Dorsal ground colour sand, slightly iridescent, with green hues in the lower two-thirds (Fig. 7 ). One dorsal and two latero-dorsal irregular dark brown bands outlined with a thin cream line. Several small round or ovoid dark-brown spots, outlined with a thin cream line, are present in between the dorsal and latero-dorsal stripes and two larger and irregular in shape are present between the eyes. Dark brown canthal stripe, outline with a cream-coloured line, from the tip of the snout extending above and around the tympanum and behind the shoulder on the right side and to a fourth of the abdomen on the left side. Several large and irregular dark brown blotches, outlined by a cream line on the flank, in the continuation of the canthal stripe on each side. Tympanum golden light brown. Upper lip iridescent sand colour with a few irregular brown markings. Iris dark gold, lighter on the upper third, with heavy black reticulation. Flanks sand colour dorsally to forest green ventrally, with small black round spots. An irregular dark grey blotch marks the limit between the flank and the ventrum. Throat and ventrum mostly cream, yellowish towards the flanks, with small light brown blotches laterally. Hands, arms and forearms sand colour to green posteriorly, with a few irregular dark brown spots, except on the hands. Tibia light brown with irregular green blotches and a few small and irregular black spots. Thighs green dorsally to dark, bluish-green posteriorly, with a few irregular brown blotches. Feet green towards the heel to light olive green towards the toes.

Colouration of the holotype in preservative.

Dorsal ground colour bluish-grey with large irregular black bands and spots outlined by a white line (Fig. 7B ). Hands, feet and limbs bluish-grey with a few irregular black spots on the forearms and tibias, outlined with white. Throat and ventrum white to cream with a few faint brown spots. Ventral side of the hands, feet and tibiae heavily dusted with grey.

Variation.

Dorsum can be green to dark green, sand or brown. All examined specimens had light or dark brown to black irregular markings, variable in size and number, on the dorsum. In many individuals, those markings are bi- or tricolour (yellowish-cream, light and dark brown) and form lateral and dorso-lateral ocelli in some animals. A thin yellowish line is present from the tip of the snout to behind the tympanum in all examined individuals. The canthal stripe can be light brown to black and can be underlined by a second yellowish line from the snout to the eye in some individuals. Flanks can be the same colour or a lighter version of the dorsal ground colour or green while the dorsum is brown or vice versa. Larger versions of the dorsal blotches are found on the flanks, sometime merging into an irregular band. Limbs are the same colouration as the dorsum and sometimes have irregular brown markings. Upper lip may be light brown or the same colour as the dorsum without any markings. Iris golden to brown. Tympanum partially or completely covered with a brown blotch, either joining the brown bar behind the eye or as a separate blotch. Throat and chest uniformly white to pale yellow. Ventrum white to orange-yellow, sometimes with yellow to orange zones on the sides and extending to the ventral side of the thighs. In gravid females, yellow eggs are visible through the thick ventral skin. Palms of the hands, ventral sides of feet and tibia more or less heavily dusted with dark grey. Dorsal skin may be smooth, slightly or very rugose.

Etymology.

The specific name refers to the Shebelle River, as the distribution range of the species appears restricted to the Shebelle River Basin, with populations found both north and south of the source of the river (Fig. 1 ).

Habitat, distribution and natural history.

Leptopelis shebellensis sp. nov. inhabits the grassy meadows of the Didda Plateau and the northern Bale Mountains at mid- to high elevations (2,429-3,296 m a.s.l.). This species is notably found near Assela, Huruta, Dinsho, Adaba, Dodola, Goba and Chole (Fig. 1 ; Suppl. material 5: table S1). Males have been heard calling both during the dry (April, June) and rainy seasons (July, August) and call both at night and during the day, for extended periods of time. Males call on the bank of streams or side pools, generally from holes in the ground, sometimes from the ground under low vegetation.

Advertisement call.

The call of Leptopelis shebellensis sp. nov. is a very short rattle. It is composed of one or two identical notes at 704 ± 85 ms interval (Fig. 4A ). When they are produced, two-note calls make up about half of the calls within a call bout. Each note is 57 ± 5 ms in duration and contains five pulses, emitted regularly with very short inter-pulse intervals (11 ± 2 ms). The relative position of the note’s amplitude peak is variable amongst individuals and may be on the first pulse, in the middle of the note or the amplitude may be equivalent for each pulse. Within a call bout, calls are spaced by 8 ± 1 seconds. Call dominant frequency is 1,616 ± 265 Hz, with a band width of 974 ± 163 Hz.

The call of Leptopelis shebellensis sp. nov. is distinguishable from the calls of L. gramineus , L. diffidens , L. sp. Kibre Mengist and L. rugosus by its higher pulse rate. It is further distinguished from the call of L. gramineus , L. diffidens and L. sp. Kibre Mengist by its shorter note duration and narrower frequency band width and from L. susanae by its longer note duration and lower pulse rate. Finally, it can be distinguished from the call of L. rugosus by its greater number of pulses per note.

Figures

Figure 1. Distribution ranges of six species of the Leptopelis gramineus species complex. Small, more arboreal forms are represented by green (L. diffidens), yellow (L. gramineus) and purple (L. xeniae sp. nov.) triangles. Larger, semi-fossorial forms are represented by red (L. rugosus) and white (L. shebellensis sp. nov.) circles. The large arboreal Leptopelis susanae is represented by a light blue triangle. Stars indicate type localities given in the original descriptions of L. gramineus (yellow; dashed line between Badditu and Dime), Pseudocassina rugosa (red) and Pseudocassina ocellata (grey), both synonymised here with L. rugosus (see the discussion in the main text).

Figure 4. Advertisement calls of six Leptopelis species inhabiting the Ethiopian Highlands A L. shebellensis sp. nov. (SB 61) B L. rugosus (SB 609) C L. gramineus (SB 212) D L. xeniae sp. nov. (SB 169) E L. diffidens (SB 134) F L. susanae (SB 223).

Figure 7. Leptopelis shebellensis sp. nov. A male holotype (SB 482; left) and live female paratype (SB 41; right) B male holotype (SB 482; left) and dorsal and ventral views of female paratype (SB 39; right) after fixation.