Hyperolius poweri Loveridge, 1938

Channing, A., Hillers, A., Lötters, S., Rödel, O., Schick, S., Conradie, W., Rödder, D., Wagner, P., Dehling, J. M., Du Preez, L. H., Kielgast, J. & Burger, M., 2013, Taxonomy of the super-cryptic Hyperolius nasutus group of long reed frogs of Africa (Anura: Hyperoliidae), with descriptions of six new species, Zootaxa 3620 (3), pp. 301-350 : 335-339

Hyperolius poweri Loveridge, 1938

Power's Long Reed Frog ( Fig. 9 )

Genetic material. ZMB 77312–3 (Port Edward, South Africa); PEM A 9545–6 (Mkambati Nature Reserve, South Africa) ( Fig. 1 ).

Diagnosis: The advertisement call ( Fig. 13 ) consists of an initial brief note with seven pulses, followed by five slower pulses, with a duration of 0.12 s. It can be distinguished from species producing only a single note, and those producing only a buzz: H. acuticeps , H. adspersus , H. dartevellei , H. jacobseni , H. lupiroensis , and H. nasutus . It differs from species producing a call over 0.2 s; H. benguellensis , H. inyangae and H. viridis . See Table 3 for a summary of call parameters. The snout is bluntly rounded, distinguishing it from those with truncated, shark-like or sharply rounded snouts: H. acuticeps , H. benguellensis , H. dartevellei , H. friedemanni , H. howelli , H. inyangae , H. lupiroensis , H. nasutus , and H. rwandae sp. nov. There is a phalanx free of web on the first and third toes, with slightly more than a phalanx free on the fourth toe. The second and fifth toes have about half a phalanx free of web. It can be distinguished from the species that have at least one toe webbed to the disc: H. adspersus , H. benguellensis , H. friedemanni , H. jacobseni , H. lupiroensis , H. nasutus and H. rwandae sp. nov. It differs from the species that have the fifth toe with one or more phalanges free of web: H. acuticeps , H. dartevellei , H. howelli , and H. inyangae .

Description of a specimen from Mkambati. This is a male, PEM A 9545, collected at the Mkombati Nature Reserve, Eastern Cape Province, South Africa by J. Venter and W. Conradie, 8 February 2011. Body long and slender, widest at mid-body, slightly tapering to groin; head comparatively small (HL/SUL 0.30, HW/SUL 0.30), not wider than trunk, length subequal to width (HL/HW 0.98); snout long (SL/HL 0.49), sharply rounded in dorsal view, blunt in profile ( Fig. 6 ), projecting beyond lower jaw, wider than long (SL/EE 0.75); canthus rostralis distinct, rounded, slightly concave from eye to just beyond nostril, slightly convex near tip of snout; loreal region almost vertical, slightly concave; nostril directed laterally; situated much closer to tip of snout than to eye (EN/NS 1.46), separated from each other by distance greater than distance between eye and nostril (NN/EN 1.16); eyes directed anterolaterally, moderately protruding, relatively small (ED/HL 0.34); eye diameter shorter than snout (ED/SL 0.70); interorbital distance wider than upper eyelid (IO/EW 1.14), and greater than internarial distance (IO/ NN 1.09); tympanum not visible externally; upper jaw with dentition; teeth on premaxilla larger than those on maxilla; choanae small, oval, located far anterolaterally at margins of roof of the mouth; vomer processes and teeth absent; tongue long 5.1, and narrow (2.3 at widest point), free for about three-fourths of length, bifurcated distally for about one-fourth of length; median lingual process absent; vocal sac single, median, subgular, mostly unpigmented and translucent when fully inflated; gular flap consisting of two areas of thickened skin, immediately adjacent to each other; anterior part cream-coloured, larger, more granular, and thicker than posterior whitecoloured part; in resting position only a narrow band of the posterior part visible from below; vocal sac aperture on each side of the mouth, situated lateral from and close to base of tongue, slit-like.

Dorsal surfaces of head, trunk and limbs generally smooth; ventral surface of limbs and gular smooth.

Fore limbs slender; hand moderately large (HND/SUL 0.27); tips of fingers enlarged into broad oval disks, each with circummarginal groove; relative length of fingers: I<II<IV<III; subarticular tubercles rounded, well developed, with one on fingers I and II, two on fingers III and IV, with proximal tubercle on finger IV hardly discernible; webbing formula of the hand I 2– 2 II 2.5– 3 III 3–2.5 IV; thenar tubercle indistinct, low; palmar tubercles absent; metacarpals without supernumerary tubercles; nuptial pads or asperities absent.

Hind limbs slender, moderately long (LEG/SUL 1.5); tibio-tarsal articulation passing level of tip of snout when legs are adpressed to body; tibiofibula moderately long (TFL/SUL 0.52), subsequal to thigh (TFL/THL 1.04); heels overlapping each other when knees are flexed and thighs are held laterally at right angle to body; foot shorter than tibiofibula (FOT/TFL 0.81); relative length of toes: I<II<III<V<IV; discs of toes smaller than those of fingers; subarticular tubercles: one on toes I and II, two on toes III and V, and three on toe IV; pedal webbing formula ( Fig. 7 ) I 1 –1.5 II 0.75– 2 III 1– 2 IV 1.5–0.5 V; inner metatarsal tubercle small, oval, prominent; outer one indistinct.

Colouration in life. In life the body is dark green with pale flecks, and fine brown pigment spots. The lateral stripes are shiny white, with a subdermal paradorsal band visible as an irregular pale green band. The toes have reddish tips. Colouration in preservative. In preservative the lateral stripes are shiny white, originating at the nostrils, being pale and subdermal before running over the eyes, and extending back to the groin. The back is densely covered in small chromatophores, with very dark pigment over the snout. The gular region is pale with a few dark spots

Eggs and tadpoles. The eggs are white with a grey animal pole, less than 1 mm in diameter, within capsules 2.2 mm in diameter (Wager 1986). Clutch size is about 200, with the eggs being deposited in small groups attached to vegetation under water (Wager 1986). Wager (1986) described the tadpoles.

Habitat. The frogs are found on reeds and other emergent vegetation around pools and swamps.

Distribution. This species is only confirmed from the east coast of South Africa, from Mkambati in the south, northwards to the Mozambique border. The northern extent of the distribution is unknown.

Remarks. The species is only known from the north-eastern coastal strip of South Africa. Due to the disturbed coastal habitat, this species should be regarded as Data Deficient in terms of the IUCN criteria, until further studies are carried out.

Holotype. ZMB 77221, adult male, from a pond in farmland on the eastern outskirts of Butare, Huye District, South Province, Rwanda (2°37'10.79'' S, 29°45'08.45'' E), collected 13 September 2010 by J.M. Dehling.

Genetic material. ZMB 77221–2 (Butare, Rwanda); ZMB 77223–4 (Mugesera wetland, Rwanda); ZMB 77225 (Akagera wetland, Rwanda) ( Fig. 1 ).

Paratypes. ZMB 77222, adult male, same data as holotype; ZMB 77423–24, 77426–29, six adult males, ZMB 77425, adult female, all from farmland on the eastern outskirts of Butare, Huye District, South Province, Rwanda, collected in October 2009 by K. Lümkemann, K. Rosar and C. Schwartz; ZMB 77686–89, four adult males, from farmland on the eastern outskirts of Butare (2°35'44.1'' S, 29°45'25.6'' E), collected 27 February 2012 by J.M. Dehling; ZMB 77223, adult female, from the Mugesera wetland south of Lac Mugesera, Bugesera District, East Province, Rwanda (2°12'18.92'' S, 30°16'18.18'' E), collected 27 March 2011 by J.M. Dehling; ZMB 77224, adult male, from the Mugesera wetland, Bugesera District, East Province, Rwanda (2°12'15.95'' S, 30°15'49.25'' S), collected 27 March 2011 by B. Dumbo and J.M. Dehling; ZMB 77683 juvenile, ZMB 77684 adult female, ZMB 77685 adult male, all from the Mugesera wetland, Bugesera Province, southeastern Rwanda, collected 26 February 2012 by J.M. Dehling; ZMB 77225, adult male, from a wetland of the Akagera River, Kihere District, East Province, Rwanda (2°13'27.63" S, 30°49'39.06" E), collected 31 March 2011 by J.M. Dehling; ZMB 77746–48, three adult males, from a swamp in farmland on the eastern outskirts of Ruhengeri, Musanze District, North Province, Rwanda (1°30'25.73" S, 29°39'12.11" E), collected 30 March 2012 by J.M. Dehling.

Diagnosis: The advertisement call ( Fig. 13 ) consists of an initial brief note of 13 pulses, followed by three slower pulses, with a duration of 0.14 s. It can be distinguished from species producing only a single note, and those producing only a buzz: H. acuticeps , H. adspersus , H. dartevellei , H. jacobseni , H. lupiroensis , and H. nasutus . It differs from species producing a call over 0.2 s: H. benguellensis , H. inyangae and H. viridis . It differs from the species that have five or more slower pulses: H. friedemanni , H. igbettensis and H. poweri . The initial note of the call of H. howelli consists of only eight pulses, distinguishing it from H. rwandae with 13. See Table 3 for a summary of call parameters. The snout is sharply rounded in profile, which distinguishes it from those species with truncated, shark-like, or bluntly rounded snouts: H. adspersus , H. benguellensis , H. dartevellei , H. howelli , H. igbettensis , H. inyangae , H. jacobseni , H. poweri , and H. viridis . The third and fifth toes webbed three-fourth the way between disc and distal subarticular tubercle, distinguishing it from the species where the webbing does not reach beyond the distal subarticular tubercles of the third and/or fifth toe: H. acuticeps , H. benguellensis , H. dartevellei , H. howelli , H. igbettensis , H. inyangae , H. nasutus , H. poweri , and H. viridis . It differs from H. friedemanni which has all the toes webbed to the disc, and from H. lupiroensis and H. nasutus which have three phalanges free of web on the inner side of the fourth toe. Standard measurements of the holotype are compared with the other species in Appendix 2.

Description of Holotype. Body long and slender, widest at temporal region, slightly tapering to groin; head comparatively small (HL/SUL 0.33, HW/SUL 0.30), not wider than trunk, longer than wide (HL/HW 1.10); snout long (SL/HL 0.44), pointed in dorsal view, acute in profile ( Fig. 6 ), considerably projecting beyond lower jaw, wider than long (SL/EE 0.77); canthus rostralis distinct, moderately sharp, almost straight-lined from eye to just beyond nostril, slightly convex near tip of snout; loreal region almost vertical, slightly concave; nostril directed dorsolaterally; situated much closer to tip of snout than to eye (EN/NS 1.42), separated from each other by distance greater than distance between eye and nostril (NN/EN 1.13); eyes directed anterolaterally, moderately protruding, relatively small (ED/HL 0.31); eye diameter shorter than snout (ED/SL 0.70); interorbital distance much wider than upper eyelid (IO/EW 1.71), and greater than internarial distance (IO/NN 1.16); tympanum not visible externally; upper jaw with dentition; teeth on premaxilla larger than those on maxilla; choanae small, oval, located far anterolaterally at margins of roof of the mouth, concealed by upper jaw for about the half in ventral view; vomer processes and teeth absent; tongue long 4.9, and narrow (2.4 at widest point), free for about three-fourths of length, bifurcated distally for about one-fourth of length; median lingual process absent; vocal sac single, median, subgular, mostly unpigmented and translucent when fully inflated; gular flap consisting of two medially arranged, subcircular areas of thickened skin, immediately adjacent to each other; anterior part cream-coloured, larger, more granular, and thicker than posterior white-coloured part; in resting position only anterior part visible from ventral; vocal sac aperture on each side of the mouth, situated lateral from and close to base of tongue, slit-like, long, directed posterolaterally.

Dorsal surfaces of head, trunk and limbs generally appearing smooth but with many densely and more or less evenly scattered tiny, low, spine-like tubercles, hardly visible with the naked eye; ventral surface of limbs and gular smooth, chin and abdomen slightly more areolate; supratympanic fold absent.

Fore limbs slender; hand moderately large (HND/SUL 0.29); tips of fingers enlarged into broad oval disks, each with circummarginal groove; relative length of fingers: I<II<IV<III; subarticular tubercles rounded, well developed, with one on fingers I and II, two on fingers III and IV, with proximal tubercle on finger IV hardly discernible; webbing formula of the hand I 2 +– 2 II 2–2.75 III 2–2 -IV (after Myers & Duellman [1982]); thenar tubercle indistinct, low; palmar tubercles absent; metacarpals without supernumerary tubercles; nuptial pads or asperities absent.

Hind limbs slender, moderately long (LEG/SUL 1.63); tibio-tarsal articulation reaching to level of tip of snout when legs are adpressed to body; tibiofibula moderately long (TFL/SUL 0.54), longer than thigh (TFL/THL 1.11); heels overlapping each other considerably when knees are flexed and thighs are held laterally at right angle to body; foot shorter than tibiofibula (FOT/TFL 0.81); relative length of toes: I<II<III<V<IV; discs of toes smaller than those of fingers; subarticular tubercles: one on toes I and II, two on toes III and V, and three on toe IV; pedal webbing formula ( Fig. 7 ) I 1.5–2+ II 1.25–2+ III 1.25– 2 IV 2-–1.25 V; inner metatarsal tubercle small, oval, prominent; outer one larger, almost circular, low and less distinct.

Colouration in life. Generally weakly pigmented and skin more or less translucent. Dorsum and dorsal surface of head and limbs yellowish green; lateral sides of head and scapular region light green; light, yellowishwhite, moderately broad dorsolateral stripe running along each side of the body from lateral edge of upper eyelid to groin, continued as faint, hardly discernible line from eyelid to tip of snout; very small dark brown to black dots and larger brown to reddish brown specks on dorsum, most densely along both sides of canthus rostralis and upper eyelid and to lesser extent on both sides of dorsolateral stripe; dots roundish, specks shaped like stars or neurons with many dendrites; distal portions of fingers and toes, especially the tips, yellow; ventral side and parts of dorsal side of thigh and upper arm largely unpigmented, appearing bluish-green; peritoneum white, shining through the translucent belly skin; most of internal organs covered with silvery-white tissue (only visible when dissected). Iris reddish-brown during the night, yellowish-brown during the day. Colouration in preservative. All colours have faded to yellow; gular flap whitish-yellow.

Paratype variation. The paratypes are similar to the holotype in measurements (Appendix 2). Female type specimens (SUL 18.2–20.4, mean 19.2, n=3) are about as large as males (SVL 18.4–22.0, mean 19.5, n=15). Colouration of male paratypes is similar to that of the holotype. In some specimens, however, the pattern of dots and speckles is more pronounced. In others, the lateral stripe is less distinct. The light canthal stripe is completely absent in ten male paratypes and in seven paratypes as faintly visible as in the holotype. All females observed in the field, including the female paratypes, lack the light dorsolateral and canthal stripes, gular sacs and flaps, and the spiny dorsal tubercles ( Fig. 8 ). In life, the flanks of the body turn reddish in active males, especially those which are calling.

Eggs and tadpoles. Several females with enlarged ovarian eggs were observed but only three of them were collected (ZMB 77143, 77425, 77684). Their ovaries contain about 80 enlarged eggs with a diameter of ca. 0.7–0.8. Eggs are darkly pigmented on the animal pole and white on the vegetative pole. Tadpoles are unknown.

Habitat. We found the species only in open habitats, in natural wetlands (Mugesera, Akagera) as well as at the edge of ponds and other lenthic water bodies in cultivated areas. Specimens were observed perching on leaves of vegetation between 5 cm and 1.2 m above the ground or the water level. Males called from elevated positions, sometimes in close proximity to each other (ca. 15 cm). Several males were found engaged in combat. They were holding, pushing, and kicking each other, apparently fighting over an apparently favoured calling site. They also emitted aggressive calls which differed markedly from the advertisement call. The male aggression call is shown in Fig. 14. The following species were found sympatricaly or even syntopically with the new species: Afrixalus quadrivittatus , Amietia cf. angolensis , Amietophrynus kisoloensis , A. regularis , Hyperolius cinnamomeoventris , H. kivuensis , H. lateralis , H. viridiflavus , Kassina senegalensis , Leptopelis kivuensis , Phrynobatrachus cf. mababiensis, P. natalensis , Phrynobatrachus sp., Ptychadena anchietae , P. porosissima , P. cf. mascareniensis , Ptychadena sp. and Xenopus victorianus .

Distribution. We observed the species at three further locations in Rwanda, near Gitarama (2°05'57.14'' S, 29°46'41.94'' E, Muhanga District, Southern Province, central Rwanda) and west of Kigali (1°57'49.11'' S, 30°00'05.87'' E, Kamonyi District, Southern Province, central Rwanda; and 1°56'59.33'' S, 30°00'48.97'' E, Nyarugenge District, Kigali Province, central Rwanda). The localities from where the species is known are in the northern, central, southern and eastern parts of Rwanda. Elevations of the sites ranged from 1300 m (Akagera wetland) to 1800 m (Ruhengeri). Population size was high at all sites. Because the locations in Butare, Mugesera, and Akagera are only 17 km and 15 km from the border with Burundi and 1.6 km from the border with Tanzania, respectively, and especially because the wetlands of Mugesera and Akagera continue into Burundi and Tanzania, respectively, we assume that the species occurs in these countries as well.

Etymology. The species epithet derives from Rwanda. It is a noun in genitive singular.

Remarks. Although the species is so far only known from several localities in Rwanda, it is probably more widespread. The species occurs in both natural and cultivated areas. Therefore, we propose that it should be classified as Least Concern under the current criteria of the IUCN redlist.

Figures

FIGURE 1. Map showing the distribution of the sequenced specimens of recognised species in the Hyperolius nasutus group plus H. lamottei. Species numbers represent the following: 1 — H. acuticeps, 2 — H. adspersus, 3 — H. benguellensis, 4 — H. friedemanni sp. nov., 5 — H. howelli sp. nov., 6 — H. igbettensis, 7 — H. inyangae sp. nov., 8 — H. jacobseni sp. nov., 9 — H. lamottei, 10 — H. lupiroensis sp. nov., 11 — H. nasutus, 12 — H. poweri, 13 — H. rwandae sp. nov., 14 — H. dartevellei, 15 — H. viridis, 16 — H. nasicus.

FIGURE 6. Snout profiles of representatives of the species in the Hyperolius nasutus group.

FIGURE 7. Webbing diagrams of representatives of the species in the Hyperolius nasutus group.

FIGURE 8. Advertisement calls of H. benguellensis Humpata (left) and H. friedemanni Karonga (right).

FIGURE 9 Hyperolius nasutus, Calandula, Angola, ZMB 77311, photo A. Channing (A); Hyperolius poweri, Mkambati NR, South Africa, photo W. Conradie (B); Hyperolius rwandae sp. nov., Butare, Rwanda, ZMB 77221, holotype, photo J. M. Dehling (C); Hyperolius viridis, Kaningina, Malawi, photo V. Mercurio (D), Hyperolius rwandae sp. nov, female paratype ZMB 77223, photo J. M Dehling (E), Hyperolius dartevellei, Carumbo, Angola, PEM A 10035, photo W. Conradie (F).

FIGURE 13. Advertisement calls of H. nasutus Kangandala (left), H. poweri Port Edward (center) and H. rwandae Gitarama (right).