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

Common name.

English: Xenia’s African treefrog.

Type material.

Holotype. Adult male (SB183), collected on 18 April 2018 by S. Goutte and J. Reyes-Velasco east of Kibre Mengist (5.8782°N, 39.1330°E, 1832 m a.s.l.). Paratypes. One female (SB151) and two males (SB152, SB153), collected on 17 April 2018 by S. Goutte and J. Reyes-Velasco northwest of Kibre Mengist (5.9988°N, 38.8798°E, 2097 m a.s.l.), four males (SB167, SB168, SB169, SB170), collected on 17 April 2018 by S. Goutte and J. Reyes-Velasco northwest of Kibre Mengist (6.0093°N, 38.8576°E, 2105 m a.s.l.) and one male (SB184) collected on 18 April 2018 by S. Goutte and J. Reyes-Velasco east of Kibre Mengist (5.8782°N, 39.1330°E, 1832 m a.s.l.).

Other material examined.

One female (SB197) and 12 males (SB186-SB196, SB206), collected on 19 April 2018 by S. Goutte and J. Reyes-Velasco southeast of Kofele (7.0226°N, 38.8701°E, 2,561 m a.s.l.) .

Diagnosis.

Small to medium-sized (male (n = 20) SVL 27.6 ± 2.0 mm, female (n = 2) SVL 43.5 ± 5.7 mm), robust arboreal species of the Leptopelis gramineus species complex (Fig. 8 ). It differs from other members of the Leptopelis gramineus species complex by the following combination of characters: (1) thin, elongated hind-limbs (male TL/SVL 0.36 ± 0.02, female TL/SVL 0.37 ± 0.03), (2) small metatarsal tubercle (male MTL/SVL 0.07 ± 0.01, female MTL/SVL 0.06 ± 0.00) (2) inter-orbital distance very short (male IOD/ED 0.88 ± 0.16, female IOD/ED 0.69 ± 0.12), (3) dorsal skin always smooth, except in females where it may be slightly rugose, (4) absence of yellow colouration on the ventrum or inner thighs.

Comparison.

Smaller body size, narrower head than L. rugosus , L. shebellensis sp. nov. and L. susanae (Table 1 , Suppl. material 5: table S9). Tympanum and metatarsal tubercle smaller than L. rugosus and L. shebellensis sp. nov. Interorbital distance shorter than L. gramineus and L. diffidens . Snout narrower than L. gramineus , L. rugosus and L. shebellensis sp. nov. and more elongate (snout-nostril distance greater) than L. gramineus and L. diffidens . Hind-limbs and feet longer than in L. gramineus , L. rugosus and L. shebellensis sp. nov. (Table 1 , Suppl. material 5: table S9).

Description of the holotype.

Small-sized male (SVL 28.9 mm) adult (Fig. 8 ). Body robust. Head a third of body size in length, wider than long (HW/HL 1.16). Snout angular and narrow (IND/IOD 0.75). Nostril beyond half-way between the tip of the snout and the eye (NS/SL 0.56). Canthus rostralis well-marked and loreal region slightly concave. Pupil vertical. Tympanum clearly visible, and round, 0.71 × eye diameter. Fingers and toes thin and elongated with discs barely expanded, but distinct, ovoid. Finger formula: I <II <IV <III. Hand free of webbing. Hind-limbs relatively long for the L. gramineus species complex (TL/SVL 0.38 and THL/SVL 0.42 vs. TL/SVL <0.37 and THL/SVL <0.40 in other species of the L. gramineus complex, except L. susanae ). Foot 1.2 × tibia length. Inner metatarsal tubercle present, oval in shape, 0.21 × foot length. Outer metatarsal tubercle absent. Toe formula: I <II <V <III <IV. Foot webbing minimal. Skin of the dorsum and flanks smooth, ventrum rugose.

Colouration of the holotype in life.

Dorsal ground colour grey-brown with three dark, but very faint, wide bands; the central band forming a triangle pointing towards the snout and each eye and extending along the spine to about three-fourths of the dorsum (Fig. 8A ). Two similarly-coloured symmetrical bands on each side, starting behind the shoulder and fading away at the same level as the dorsal stripe. A few small dark brown spots on the head and dorsum. Black canthal stripe from the tip of the snout extending above the tympanum and behind the shoulder on the left side and to a third of the abdomen on the right side. One large black blotch on the flank, in the continuation of the canthal stripe on each side. Tympanum light grey dusted with small black spots. Upper and lower lip light grey with small irregular black markings. Iris dark gold, lighter on the upper third, with heavy black reticulation. Flanks grey, yellow towards the thighs, with irregular black blotches. Ventrum and throat cream, reticulated with light grey on the chest. Limbs, hands and feet grey dusted with small black freckles. Back of the thighs dark brown with irregular bluish-grey and yellowish-grey markings.

Colouration of the holotype in preservative.

Dorsal ground colour grey with a few small irregular dark grey spots (Fig. 8B ). The faint three-bands pattern formed by these small dark grey spots is almost completely undistinguishable. Hands, feet and limbs grey with a few irregular dark grey spots. Back of the thighs dark brown with irregular light grey blotches. Throat and ventrum cream with some light brown or grey dusting. Ventral side of the thighs cream. Ventral side of the hands, feet and tibiae heavily dusted with brown and with a few irregular white spots.

Variations.

As with other members of the Leptopelis gramineus species complex, L. xeniae sp. nov. shows significant colour polymorphism. Dorsal colouration varies from light grey (with or without some light green) or light brown to bright or dark green with important level of dark pigmentation. Most individuals examined display a similar dorsal pattern composed of three bands, which can be barely distinguishable to well-marked. The canthal stripe may extend as a wide dark brown to black stripe on the flank to four-fifths of the abdomen or be replaced by large blotches of the same colour. Limbs are the same colouration as the dorsum, with variable number of small to medium brown or black markings. Upper lip may be cream, light grey or green, with variable size and number of irregular brown or black markings. Iris golden to dark golden. Tympanum dark brown or black either entirely or on its upper half, with the lower half being the same colour as the dorsum. Rarely, the tympanum is entirely the same colour as the dorsum. Lower lip cream mottled with brown or grey or with a continuous brown blotch. In one female (SB151), the lower lip was light green with a few brown markings. Ventrum and throat white, with small brown blotches on either or both in most individuals. Inner thighs white or lacking any pigmentation, except dark brown and yellow spots towards the knee in some individuals. Cream-coloured eggs visible through the thick ventral skin of the gravid female SB151. Dorsal skin smooth in all specimens examined, except in the female SB197, which had a slightly rugose dorsal skin.

Etymology.

Leptopelis xeniae sp. nov. is named after Xenia Freilich, who conducted her doctoral research on Ethiopian anurans, including the Leptopelis gramineus complex.

Habitat, distribution and natural history.

Leptopelis xeniae sp. nov. is found in the forested areas around the towns of Kibre Mengist and Kofele, Oromia, Ethiopia (5.87-7.02°N, 38.80-39.13°E; Fig. 1 , Suppl. material 5: table S1). The species occupies lower elevations than most other members of the L. gramineus species complex (1,832-2,561 m a.s.l.). Males are found calling at night from the ground or from vegetation up to 60 cm high, close to slow-flowing streams or in flooded forest clearings. Reproductive biology is unknown beyond the calling behaviour and we have not encountered eggs or tadpoles.

Advertisement call.

As for other members of the Leptopelis gramineus species complex, the call of Leptopelis xeniae sp. nov. is a short rattle (Fig. 4D ). It is composed of a single note of 175 ± 25 ms in duration, containing 7 ± 2 pulses, which are clearly distinct. Within a note, pulses are spaced by intervals of 30 ± 5 ms. These inter-pulse intervals may be of equal length throughout the note or shorter between the last pulses. Amplitude is highest for the first quarter to half of the note and decreases in its last quarter. Within a call bout, calls are spaced by 14 ± 7 seconds, often with an acceleration of call rate starting with one call every 22 seconds to one note every four seconds. Call dominant frequency is 2,231 ± 585 Hz, with an important band width (2,013 ± 573 Hz).

The call of Leptopelis xeniae sp. nov. is distinguishable from the calls of L. gramineus , L. diffidens , L. shebellensis sp. nov., L. rugosus and L. susanae by its longer note and longer inter-pulse intervals (Fig. 4 , Table 2 ). It is further distinguished from the call of L. shebellensis sp. nov. and L. rugosus by a greater number of pulses per note, a higher peak frequency and a wider frequency band width (Table 2 ).

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 8. Leptopelis xeniae sp. nov. A live male holotype (SB 183; left) and female paratype (SB 151; right) B dorsal and ventral views of the male holotype (SB 183) after fixation C dorsal and ventral views female paratype (SB 151) after euthanasia and before fixation.