Phrynobatrachus mayokoensis, Rödel, Mark-Oliver, Burger, Marius, Zassi-Boulou, Ange Ghislain, Emmrich, Mike, Penner, Johannes & Barej, Michael F., 2015

Rödel, Mark-Oliver, Burger, Marius, Zassi-Boulou, Ange Ghislain, Emmrich, Mike, Penner, Johannes & Barej, Michael F., 2015, Two new Phrynobatrachus species (Amphibia: Anura: Phrynobatrachidae) from the Republic of the Congo, Zootaxa 4032 (1), pp. 55-80 : 67-72

Phrynobatrachus mayokoensis sp. nov.

Fig. 6

Holotype. ZMB 81732 (female; field # MBUR 3833), Republic of the Congo, Niari Department, Lekoumou, about 23 km E of Tsinguidi, about 4 km SE of Mayoko Posté, start of path to site 20, 740 m a.s.l., 02°26’05.6’’ S, 12°56’16.9’’ E, 18 November 2013, coll. M. Burger & A.G. Zassi-Boulou.

Paratype. ZMB 81733 (female, field # MKO 001), Republic of the Congo, Niari Department, Mount Lekoumou, about 4 km south-east of Mayoko Posté, 704 m a.s.l., 02°19’04.5’’ S, 12°49’34.5’’ E, 31 March 2012, coll. A.G. Zassi-Boulou & P. Moukala.

Diagnosis. The genetic data (16S rRNA) characterize the new species as a member of the genus Phrynobatrachus . Morphologically this is confirmed by: the general body shape and presence of a tarsal tubercle. From the morphologically similar Arthroleptis they differ by lacking a median dorsal skin raphe and a black tympanic spot; from juvenile Ptychadena they can be distinguished by lacking parallel dorsal ridges and pedal webbing.

The new species can be distinguished from other Phrynobatrachus by the following combination of characters: small size; compact body shape; short round snout; absence of a black lateral mask, absence of a spiny eyelid tubercle; females with conspicuous ventral pattern with a white throat carrying the tip of a dark figure originating in the pectoral region, belly white; very conspicuous red blotch on anterior craniad bases of thighs, bordered by black line; short comma-shaped scapular ridges diverging posteriorly; dorsal skin tuberculate, warts particularly abundant and spiny on rear of back; flanks with some larger warts; absence of discs on finger and toe tips; no webbing and a unique 16S rRNA sequence.

Differential diagnosis. The new species differs from other western African Phrynobatrachus species by: body size being distinctly smaller than 20 mm (species with adults larger than 20 mm: P. acridoides , P. africanus , P. auritus , P. batesii , P. brongersmai , P. cornutus , P. cricogaster , P. danko , P. francisci , P. giorgii , P. intermedius , P. jimzimkusi , P. latifrons , P. liberiensis , P. plicatus , P. natalensis , P. njiomock , P. sandersoni , P. schioetzi , P. steindachneri ); the absence of a spiny eyelid tubercles (spiny eyelid tubercle present in P. annulatus , P. calcaratus , P. cornutus , P. pintoi , P. taiensis , P. villiersi ); absence of a dark lateral face mask (black face mask present: P. auritus , P. batesii , P. chukuchuku , P. horsti sp. nov., P. intermedius , P. plicatus , P. ruthbeateae ; less distinct brown face mask: P. w e r ne r i); tympanum present—although not very distinct (tympanum absent according to original description: P. ogoensis ; indistinct but visible in BMNH 1947.2.6.83); distinct short, chevron shaped pair of scapular ridges (scapular ridges long and converging towards mid-body, almost X-shaped: P. alleni , P. auritus , P. brongersmai , P. jimzimkusi , P. plicatus , P. steindachneri ; scapular ridges indistinct or absent: P. hieroglyphicus , P. intermedius , P. liberiensis , P. maculiventris , P. manengoubensis , P. tokba ); very tuberculate dorsal skin (smooth skin: P. fraterculus , P. hieroglyphicus , P. maculiventris , P. manengoubensis , P. tokba ; almost smooth, scapular ridges present: P. rainerguentheri , P. schioetzi ); ventral skin smooth (ventral skin with asperities: P. chukuchuku ); absence of a very distinct large black axillary blotch or black band on flanks—anterior flank only with indistinct black pattern (distinct black blotches and/or bands on flank: P. dispar , P. fraterculus , P. gutturosus , P. maculiventris , P. pintoi , P. ruthbeateae ; some P. cornutus ); venter white with a dark triangle originating in pectoral region and tip extending to posterior part of throat (belly at least partly yellow in P. batesii , P. werneri ; orange to yellow: P. danko ; white or bluish with black pattern: P. villiersi ; white with blackish spots or dots: P. annulatus , P. ghanensis , P. hylaios , P. maculiventris , P. pintoi ; a black circle and median spot on white or yellow backgroundbull’s eye pattern: P. cricogaster ; white with brown mottling: P. intermedius , P. jimzimkusi , P. njiomock , P. steindachneri ); lower parts of hind limbs white with some dark patterning at the edges (yellow: P. alleni , P. batesii , P. danko , P. manengoubensis ; greyish/brownish to yellowish in P. ruthbeateae , P. schioetzi ; vaguely dark blotched in P. hylaios ); absence of a blue band along the interior half of ventral shanks (present in P. auritus ); presence of a distinct red spot at the anterio-dorsal bases of thighs, bordered by black line (not known in any other Phrynobatrachus ); absence of pedal webbing (webbing well developed: P. acridoides , P. africanus , P. alleni , P. auritus , P. brongersmai , P. cricogaster , P. danko , P. elberti , P. francisci , P. giorgii , P. intermedius , P. jimzimkusi , P. latifrons , P. liberiensis , P. natalensis , P. njiomock , P. ogoensis , P. plicatus , P. rainerguentheri , P. steindachneri , P. sternfeldi ); no discs on toe and finger tips (discs present, roundish: P. cornutus , P. guineensis , P. horsti , P. leveleve , P. phyllophilus , P. ruthbeateae , P. sternfeldi ; discs heart shaped: P. sandersoni ); small round tarsal tubercle (numerous tarsal tubercles fused to tarsal ridge: P. cricogaster ).

A detailed comparison with the genetically most similar species is given in the discussion. For further character states of western African Phrynobatrachus species see the literature cited at the end of the differential diagnosis paragraph for P. horsti sp. nov.

Description of holotype [measures in mm]. Typical, small female Phrynobatrachus with short roundish, compact body shape; snout-vent length: 15.9; short snout, rounded in dorsal and lateral view; canthus rostralis rounded; loreal region straight; head-width directly behind the eyes: 5.5; large eyes positioned laterally; eyediameter: 2.1; distance anterior corner of eye to nostril: 1.5; nares small and round, positioned laterally; straight distance nostril-snout tip: 0.9; nostril much closer to snout than to eye; inter-narial distance: 2.0, much larger than inter-orbital distance (distance between eyelids): 1.1; pupil round; supratympanic ridge curving down from slightly ventrad of posterior corner of eye towards forearm bases (in preservation indistinct and vanishing just posterior to tympanum); tympanum indistinct, diameter: 0.9, no tympanic annulus; tympanum much smaller than diameter of eye; upper maxillae with minute teeth, hidden by lips; vomerine teeth absent; broad, almost heart shaped tongue, tip broad and almost straight, median conical papilla near tongue tip; tongue smooth to slightly granular; small round choanae positioned at anterior-lateral edges of mouth roof.

Forelimbs long and slender; upper arm: 3.9; lower arm: 3.7; hand to tip of finger III: 3.8; hand with two large tubercles, oval thenar tubercle, large and round palmar tubercle; fingers with round, non-divided, protruding subarticular tubercles, no further tubercles on hand and fingers; relative finger length: IV≤II=I<III; manual webbing absent; finger tips rounded, not forming discs, as wide as subarticular tubercles; hind limb moderately long and slender; femur: 8.0, slightly shorter than tibia: 8.2 (left tibia: towards knee tissue and skin extracted for molecular analyses); tibia length 51.6% of SVL; foot including longest toe: 12.2; tarsal tubercle present, small and round; large inner metatarsal tubercle: 0.8, long and narrow, almost half length of toe I (right side: 1.8; left side: 2.0); small round outer metatarsal tubercle; slender toes; relative toe length: I<II<V<III<IV; pedal webbing absent; toe tips rounded without forming discs, being approximately as wide as subarticular tubercles; undivided subarticular tubercles round to elongate.

Dorsal skin tuberculate (in life) to mostly smooth (in preservation); a pair of chevron shaped warts on neck, the anterior parts of these warts shorter, parallel to body and to each other, the posterior parts of the warts longer, extending towards flanks; flanks and anterior part of back with smaller and larger flat warts (not visible in preservation); posterior third of back with distinct and pointed warts (in preservation: round); eyelid, interorbital space, dorsal parts of thighs towards knees and lower legs with many distinct and pointed warts (in preservation round: eyelids, or invisible: extremities); spiny eyelid tubercle absent; skin on lower parts of head, limbs, belly and pectoral region smooth.

Sex determined via dissection: few small, white ovarian eggs, presumably not fully developed.

Colouration in ethanol after one year. Back and dorsal part of flanks and extremities light brown; snout almost uniform light brown; upper eyelids dark grey; interorbital area mottled dark brown; back posterior to scapular region with dark brown triangle, pointing towards head; posterior third of back slightly darker, large warts almost black; remaining back and flanks with few smaller and irregular shaped darker patches; lower arms with two indistinct dark cross-bars; anterio-dorsal part of femur—bordering groin area—with lighter area (red in life, see below), bordered by black line; femur and tibia with one distinct and 1-2 indistinct darker crossbars; foot and toes with dark crossbars; upper lip with three dark blotches on either side; tympanum carrying dark blotch; lower lip white with four dark blotches on either side; throat white with a black triangular figure pointing towards mouth tip, originating on level with forearm bases; belly white, anterior half with small round dark spots (two on right, three on left side); lower parts of extremities white, edges with greyish specking; lower part of thigh with some dark mottling.

Colouration in life ( Fig. 6 ). Basic colour of head, anterior two thirds of back, flanks and anterior extremities reddish brown; anterior part of eyelids and interorbital space with dark pattern; posterior parts of the two chevron like scapular ridges enclose a medial dark figure on the back; anterior part of flanks darker brown; upper lip with three dark patches on each side; tympanum with dark spot; upper two-thirds of iris brownish-golden, lower third greyish; bases of forearms almost white; elbow and lower arm with dark mottling. Basic colour of posterior third of back and dorsal parts of hind limbs dark brown; thighs, tibiae and feet with dark crossbars; warts on posterior part of back and lower legs reddish brown; dorso-craniad bases of thighs with large red blotch, bordered by distinct black line. Ventral colouration as in preservation.

Variation. Paratype in bad state of preservation, flattened; right foot missing, right thumb short and fat (presumably healed injury); otherwise almost identical to holotype; back with slightly more dark patterning, crossbaring on extremities more pronounced; ventral pattern as in holotype. Measures are summarized in Table 4 . Males are currently unknown.

Genetics. Compared to 40 West African and Central African species of the genus Phrynobatrachus , P. mayokoensis sp. nov. exhibited a mean difference between 1.34–16.98% in the sampled region of the 16S rRNA gene ( Table 5 ). The genetically most similar sample was a frog determined as P. ogoensis by Larson & Zimkus (2015; MCZ A-149217, GenBank: KP247505 ; the second most similar species being P. dispar with a mean difference of 5.27%). However, a comparison of the new species with two P. ogoensis syntypes (BMNH 1947.2.6.83-84) revealed that P. ogoensis is not conspecific with P. mayokoensis sp. nov. (see discussion). It thus seemed, that the Gabonese frog is either conspecific with P. mayokoensis sp. nov. or represents a further undescribed taxon. The intraspecific difference between the two P. mayokoensis specimens was 0.20%. From the morphologically most similar species, P. cornutus , P. mayokoensis sp. nov. differed by 7.33–7.53%. Genetically, Phrynobatrachus mayokoensis sp. nov. is most similar to various West and Central Africa species of the clade B sensu Zimkus et al. (2010).

Distribution. Phrynobatrachus mayokoensis sp. nov. is only known from two localities in the Mayoko District of the Niari Department, south-western Republic of the Congo, close to the border with Gabon ( Fig. 4 ). It might also occur in the Ogooué-Ivindo Province of Gabon ( Larson & Zimkus 2015; compare above).

Habitat and natural history. The mid altitude habitat (740 m a.s.l.) of the holoytpe is shown in Figure 7 a. There it was encountered during the day (3:15 pm), being active on the forest floor, within 20 m of a road. The nearest wetland was a stream about 180 m away at an altitude of 673 m. The habitat of the paratype ( Fig. 7 b) likewise consisted of mid-altitude rainforest (704 m a.s.l.) on a slope. There were no wetlands within 100 m. At both sites the forest habitat seemed relatively dry compared to forest in the surrounding region. It seems possible that the species is reproducing independently of water or in small water bodies like tree holes and water filled snail shells (compare e.g. Rödel & Ernst 2002a, b; Rödel et al. 2004).

Etymology. The species’ name refers to the type locality situated in the Mayoko District of the Niari Department, Republic of the Congo. The specific epithet is considered an invariable noun in apposition to the generic name. The suggested English name for this new species is Mayoko Puddle Frog.

Figures

FIGURE 4. Distribution of Phrynobatrachus horsti sp. nov. and P. mayokoensis sp. nov. in the Republic of the Congo and Gabon and P. ruthbeateae in Cameroon; star = type locality of P. ho r s t i sp. nov., black circles = further sites of P. ho r s t i sp. nov., white circle = P. ho r s t i sp. nov. locality from Zimkus & Larson (2013 a, b); quadrate = type locality of P. mayokoensis sp. nov.; triangle = type locality of P. ruthbeateae, lower right inset picture = position of study area within Africa; upper right inset picture = zoom into sympatric range of P. horsti sp. nov. and P. mayokoensis sp. nov. near the Gabonese boarder (map based on the ASTER Global Digital Elevation Model: www. ersdac. or. jp.).

FIGURE 6. Life colouration of adult female Phrynobatrachus mayokoensis sp. nov. (ZMB 81732, holotype) in dorsolateral view, and showing black pattern on throat and pectoral region (inset picture).

FIGURE 7. Habitats of Phrynobatrachus mayokoensis sp. nov. a) type locality; b) habitat of the paratype specimen.

Tables

TABLE 4. Measurements [mm] of the type series of Phrynobatrachus mayokoensis sp. nov. (ZMB; holotype in bold) and the two P. ogoensis syntypes (BMNH); * = extension of webbing not entirely clear, cracked; ** = not visible, potentially because specimen partly damaged; for abbreviations of measurements see Table 1.

Accession number	sex	SVL	HW	ED	IO	IN	DEN	DNS	TD	FL
ZMB 81732	female	15.9	5.5	2.1	1.1	2	1.5	0.9	0.9	8
ZMB 81733	female	15.7	5.3	1.6	1.3	2.1	1.2	0.8	-**	8.3
BMNH 1947.2.6.83	male	15.5	4.6	2.1	1.7	1.5	1.4	0.9	0.8	7.0
BMNH 1947.2.6.84	female	15.5	5.3	1.7	1.8	1.8	1.4	0.9	-**	7.4
continued.

TABLE 5. Genetic similarity of two Phrynobatrachus mayokoensis sp. nov. with 40 other West and western Central African Phrynobatrachus species. Given are minimum (min), maximum (max) and mean values of uncorrected pairwise sequence divergence, presented in % of 348 – 515 bp of the 16 S rRNA gene; sd = standard deviation; N = number of individual inter-specific comparisons; for museum accession and corresponding GenBank accession numbers see Appendix 1; * = compare text.

	min	max	mean	sd	N
acridoides	13.89	14.09	13.99	0.14	2
africanus	13.68	13.68	13.68	0	2
alleni	16.37	16.37	16.37	0	2
annulatus	7.69	7.69	7.69	0	2
auritus	15.21	15.21	15.21	0	2
batesii	12.53	12.53	12.53	0	2
calcaratus	7.10	7.10	7.10	0	2
chukuchuku	12.49	12.50	12.50	0.01	2
cornutus	7.33	7.53	7.43	0.14	2
cricogaster	12.31	12.32	12.32	0.01	2
danko	11.77	11.77	11.77	0	2
dispar	5.17	5.37	5.27	0.14	2
francisci	13.53	13.72	13.63	0.13	2
fraterculus	6.73	6.73	6.73	0	2
ghanensis	16.34	16.54	16.44	0.14	2
guineensis	15.98	16.18	16.08	0.14	2
gutturosus	7.97	7.97	7.97	0	2
horsti sp. nov.	11.70	12.72	12.11	0.21	30
hylaios	18.73	18.73	18.73	0	2
intermedius	13.52	13.52	13.52	0	2
jimzimkusi	13.11	13.11	13.11	0	2
latifrons	16.74	16.95	16.85	0.15	2
leveleve	6.34	6.34	6.34	0	2
liberiensis	14.28	14.28	14.28	0	2
maculiventris	7.39	7.58	7.49	0.13	2
manengoubensis	13.36	13.36	13.36	0	2
natalensis	16.16	16.35	16.26	0.13	2
njiomock	12.30	12.30	12.30	0	2
cf. ogoensis *	1.23	1.44	1.34	0.15	2
phyllophilus	14.34	14.35	14.35	0.01	2
pintoi	6.73	6.93	6.83	0.14	2
plicatus	15.50	15.50	15.50	0	2
rainerguentheri	15.11	15.31	15.21	0.14	2
ruthbeateae	11.49	12.17	11.80	0.25	8
sandersoni	16.97	16.98	16.98	0.01	2
schioetzi	12.93	12.93	12.93	0	2
steindachneri	12.53	12.53	12.53	0	2
tokba	14.94	14.94	14.94	0	2
villiersi	6.91	7.10	7.01	0.13	2
werneri	12.96	12.96	12.96	0	2