Mantidactylus bletzae, Scherz & Crottini & Hutter & Hildenbrand & Andreone & Fulgence & Köhler & Ndriantsoa & Ohler & Preick & Rakotoarison & Rancilhac & Raselimanana & Riemann & Rödel & Rosa & Streicher & Vieites & Köhler & Hofreiter & Glaw & Vences, 2022

Scherz, Mark D., Crottini, Angelica, Hutter, Carl R., Hildenbrand, Andrea, Andreone, Franco, Fulgence, Thio Rosin, Köhler, Gunther, Ndriantsoa, Serge Herilala, Ohler, Annemarie, Preick, Michaela, Rakotoarison, Andolalao, Rancilhac, Loïs, Raselimanana, Achille P., Riemann, Jana C., Rödel, Mark-Oliver, Rosa, Gonçalo M., Streicher, Jeffrey W., Vieites, David R., Köhler, Jörn, Hofreiter, Michael, Glaw, Frank & Vences, Miguel, 2022, An inordinate fondness for inconspicuous brown frogs: integration of phylogenomics, archival DNA analysis, morphology, and bioacoustics yields 24 new taxa in the subgenus Brygoomantis (genus Mantidactylus) from Madagascar, Megataxa 7 (2), pp. 113-311 : 271-273

Mantidactylus bletzae sp. nov.

Identity and justification.—This lineage, known from two high-elevation sites in the Southern Central East and South East of Madagascar, was newly identified in this study. It resembles species of the M. biporus and M. inaudax clades phenotypically. By the presence of dorsolateral ridges, it resembles some species of the M. inaudax clade, but in the 16S tree, it is placed more closely to species of the M. biporus clade, although its relationships are not reliably resolved. We here consider it tentatively as a member of the M. biporus clade, pending its inclusion in a future phylogenomic analysis. The new species is characterized by a high mitochondrial divergence (≥5.7% from all other species; closest species M. inaudax bona species and M. madecassus ), and an isolated position in the mitochondrial tree, without obvious close relationships to any other species. It also is concordantly differentiated in the nuclear Rag-1 gene with a unique haplotype ( Fig. 4 ). Based on the concordance of high mitochondrial divergence with nuclear differentiation, we are convinced it represents a distinct species.

Holotype.— ZSM 829/2014 ( ZCMV 14771 ), adult female, collected by A. Rakotoarison, M. Bletz, D. Edmonds, and F. Randrianasolo on 11 November 2014 at Pic d’Ivohibe Special Reserve , Camp 3 (22.49710°S, 046.95758°E, 1566 m a.s.l.), Ihorombe Region, Madagascar. A 16S barcode sequence of the holotype was obtained in this study and was included in the analysis.

Paratypes.—A total of two paratypes: ZSM 827/2014 ( ZCMV 14763 ) and ZSM 828/2014 ( ZCMV 14768 ), two adult females, with the same collection data as the holotype. Specimens from Ranomafana are not included in the paratype series as they were not examined morphologically and are genetically divergent.

Diagnosis.— Mantidactylus bletzae sp. nov. is considered to be a member of the M. biporus clade based on affinities in the 16S tree. Its precise relationships remain unclarified, as it was missing from our phylogenomic analysis. See Table 4 for a list of diagnostic morphological characters. The combination of a small body size (female SVL 26–27 mm), slightly granular dorsal skin with weakly expressed but distinctly recognisable dorsolateral ridges, presence of white spots on flanks, and absence of a white marking on the snout tip distinguishes M. bletzae sp. nov. from species of the M. betsileanus , M. curtus , M. fergusoni , M. tricinctus , and M. ulcerosus clades. Mantidactylus inaudax ( M. inaudax clade) is morphologically similar but appears to have a somewhat larger body size, no dorsolateral ridges, shorter hindlimbs, and less developed foot webbing; M. biporus has a larger body size, lacks dorsolateral ridges, and has less developed foot webbing; M. augustini has somewhat longer hindlimbs, somewhat less granular dorsal skin and less clearly expressed dorsolateral ridges, and less developed foot webbing ( Table 4 ). For a distinction from the other new species in the M. biporus , M. stelliger and M. inaudax clades, see the diagnoses in the respective species accounts below. A full list of molecular diagnostic sites in the 16S gene of M. bletzae sp. nov. in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Description of the holotype.—Adult female in excellent state of preservation ( Fig. 62 ). Tongue has been excised as tissue sample.Head as wide as body.Snout rounded in dorsal view. Nostrils directed laterally, not protuberant. Nostrils nearer to tip of the snout than to eye. Canthus rostralis weakly expressed, slightly concave. Loreal region concave.

Tympanum distinct, small, rounded, its horizontal diameter about 71% of eye diameter. Supratympanic fold present, beginning straight, bending abruptly midway towards jaw / forelimb insertion. Maxillary teeth present. Vomerine teeth present in two small rounded aggregations, positioned posterolateral to choanae. Choanae rounded. Subarticular tubercles single. Inner and outer metacarpal tubercles present. Fingers without webbing. Relative length of fingers: I<II<IV<III. Finger discs slightly enlarged. Nuptial pads absent. Foot of similar length as tibia (98%). Lateral metatarsalia separated. Inner metatarsal tubercle present, outer metatarsal tubercle poorly recognisable. Webbing formula: 1(0.5), 2i(1.25), 2e(1), 3i(2), 3e(1), 4i(2), 4e(1.5), 5(0.5). Relative length of toes: I<II<V<III<IV. Skin on the upper surface quite smooth in preservative with poorly recognisable dorsolateral folds which in life probably were more clearly visible as in other photographed specimens, along with scattered small granules. Ventral side smooth. Femoral glands absent.

Colour in preservative: dorsum light brown with a quite distinct dark brown pattern, including dark longitudinal stripes running ventral of the dorsolateral folds, some dark patches in the vertebral region, and a broad dark band between the eyes. Fore- and hindlimbs with distinct dark brown crossbands. Ventrally whitish on belly and beige on limbs, with weak dark mottling on throat and chest, and lower jaw ventrally bordered by an interrupted dark line. The colour in life was not recorded.

Variation.—Variation in measurements is given in Table 10. See Fig. 67 for colouration in life and its variation. No male specimens available to assess sexual dimorphism.

Natural history.—Poorly known. Specimens were found in a swampy area near a small pool.

Calls.— The call of this species has not been recorded.

Tadpoles.— The tadpole of this species has not been described.

Distribution.— Endemic to Southern Central East ( Fig. 7 ). This species is known from Pic d’Ivohibe Special Reserve (Camp 3, at high elevation), and Maharira in Ranomafana National Park. Elevation range: 1248–1575 m a.s.l.

Etymology.—We dedicate this species to Molly C. Bletz, who contributed to collecting the type specimens from Pic d’Ivohibe, in recognition of her substantial contributions to amphibian conservation and research in Madagascar.

Figures

FIGURE 4. Network based on sequences of the nuclear-encoded Rag-1 gene (alignment length 351 bp) from 265 specimens of Brygoomantis. The network was built from phased alleles, i.e. each sample is represented twice. The size of circles is proportional to the number of sequences with the same allele. Small black dots represent hypothetical haplotypes (not sampled or extinct) separating sampled haplotypes, when they differ by more than one mutational step.

FIGURE 7. Mantidactylus subgenus Brygoomantis species distribution based on verified records, divided by clade (Mantidactylus stelliger sp. nov. is presented alongside the inaudax clade for practicality). Colours for species correspond to those in Figs 2 and 4. Inset map shows the geographic regions of Madagascar identified by Boumans et al. (2007), referred to throughout the text.

FIGURE 62. Preserved holotype specimens of newly named species in the Mantidactylus biporus clade and of the M. stelliger clade. Scale bars equal 5 mm.

FIGURE 67. Mantidactylus bletzae sp. nov. in life, in dorsolateral, ventral, and dorsal view. (a) Adult female (ZSM 827/2014 = ZCMV 14763) from Campsite 3, Pic d’Ivohibe Special Reserve, photographed in 2014. (b,c,d) Adult female (KU336940 = CRH 125) from Ranomafana. (e,f,g) Adult female (KU336941 = CRH 146) from Ranomafana.