Mantidactylus bellyi Mocquard, 1895

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 : 205-206

Mantidactylus bellyi Mocquard, 1895

Type material.— Mantidactylus bellyi Mocquard, 1895 is based on the holotype MNHN 1893.240 (by monotypy) from ‘ Montagne d’Ambre’ (according to Guibé 1978), and this number had been given incorrectly as 1893.420 by Guibé (1950). According to the original description, there are no paratypes.

Identity.—This species was previously considered a junior synonym of M. curtus (e.g. Blommers-Schl̂sser & Blanc 1991) and was resurrected as separate species by Glaw and Vences (2006). It is the sister species of M. ulcerosus . A very extensive Brygoomantis sampling at its type locality Montagne d’Ambre, reflected by 150 sequences in our 16S data set, found only two lineages at this Massif in northernmost Madagascar: one corresponding to a lineage morphologically similar to M. betsileanus and described below as M. jonasi sp. nov., and one corresponding to specimens of a lineage typically ( Glaw & Vences 2006, 2007) assigned to M. bellyi . We obtained barcode fishing 16S data of the holotype MNHN 1893.240 and confirm this nomen has been correctly assigned.

Diagnosis.—A member of the M. ulcerosus clade as revealed by the phylogenomic analysis, and sister to the morphologically very similar M. ulcerosus . See Table 4 for a list of diagnostic morphological characters. The combination of a large body size of up to 46 mm, strongly tubercular dorsal skin in most individuals, absence of dorsolateral ridges, large tympanum size in males (10– 17% of SVL) and absence of white spots on flanks and of white marking on snout tip distinguishes M. bellyi from species of the other clades. Some species in the M. fergusoni clade can be morphologically similar, but they occur in eastern Madagascar (vs Sambirano and North West regions), and have strongly different advertisement calls ( Table 4 ). Within the M. ulcerosus clade, the species differs by its large body size and tubercular dorsal skin from M. schulzi , and by its advertisement call consisting of single calls (vs note series) from M. schulzi and M. ulcerosus . For detailed distinction from new species described herein, see the respective species accounts. A full list of molecular diagnostic sites in the 16S gene of M. bellyi in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Re-description of the holotype. Adult male in poor state of preservation. Skin on various places lacerated and completely discoloured. Body rather stout. Head wider than body. Snout rounded. Nostrils directed laterally, slightly protuberant. Position of nostrils not recognisable due to the bad state of preservation. Canthus rostralis weak, slightly concave. Loreal region weakly concave.

Tympanum distinct, large, rounded, diameter about 75 % of eye diameter. Supratympanic fold distinct, beginning straight, with a rather distinct bend midway towards jaw.

Tongue ovoid, distinctly posteriorly bifid. Maxillary teeth present. Vomerine teeth present in two rounded aggregations, positioned posterolateral to choanae.

Choanae rounded. Subarticular tubercles single. Outer metacarpal tubercle present, inner metacarpal tubercle present. Fingers without webbing. Relative length of fingers: I<II<IV<III. Finger discs slightly enlarged.

Nuptial pads absent. Foot as long as tibia (101%). Lateral metatarsalia separated. Inner metatarsal tubercle present.

Outer metatarsal tubercle present. Webbing formula: 1(0.5), 2i(1), 2e(0), 3i(1.5), 3e(1), 4i(2), 4e(1.5), 5(0).

Relative length of toes: I<II<V<III<IV. Skin on the upper surface with a few ridges on flanks. Ventral side smooth.

Femoral glands present, in external view not consisting of single, sharply delimited granules but distal ulcerous macrogland having a rather irregular tubercular surface with a median depression. Proximal granular gland field present.

Colour in preservative: dorsum beige-brown, with distinct irregular darker markings. Forelimbs light brown with very poorly defined darker markings. Hindlimbs light brown with very indistinct darker crossbands. Inguinal region without whitish spots. Snout tip seems to be without a whitish spot. Venter uniformly beige. Lower lip uniformly beige. Toe discs brown to grey, darker than feet.

Variation.—Variation in measurements is given in Table 6 . See Figs 26–27 for colouration in life and its variation. Specimens with a light vertebral stripe occur.

There is moderate sexual size dimorphism (confirmed male SVL 31.7–41.0 mm [n = 11] vs confirmed female SVL 36.7–46.4 mm [n = 12]). Males have a larger tympanum than females (HTD/ED ratio is 53–77% in females, 71–113% in males).Femoral glands in males large and distinct, orange coloured in life, with the proximal granular gland field sometimes occupying a larger surface than the distal ulcerous macrogland ( Fig. 26o ) which is relatively unusual in mantellines; the proximal granular gland field on the two opposite thighs contact each other medially. Rasolonjatovo et al. (2022) describe the genetic diversity and phylogeographic structure of M. bellyi on Montagne d’Ambre.

Natural history.—Similar to M. ulcerosus , M. bellyi is found in and along small shallow streams in primary as well as degraded rainforest and dry forest. Males were heard calling at night from the water or at the edge of the water. Rasolonjatovo et al. (2018) report on the attempted predation of a Boophis tadpole by an adult M. bellyi and reported an adult female M. bellyi repeatedly emitting a series of rapid scratch-like vocalisations from a hidden place on the rough magmatic rock forming the edge of the pool. Rasolonjatovo et al. (2020) report on thermal ecology of M. bellyi on Montagne d’Ambre across its elevational range (467–1394 m a.s.l.), and Rasolonjatovo et al. (2022) described its genetic diversity and phylogeographic structure on Montagne d’Ambre.

Calls.— The advertisement call of M. bellyi , recorded on 17 March 2000 at the entrance of Montagne d’Ambre National Park, 21.6°C air temperature ( Vences et al. 2006: CD 2, track 75), consists of a regularly pulsed note ( Fig. 28 ), emitted at irregular intervals, but not regular call series. Notes exhibited distinct amplitude modulation, with call energy being highest at the beginning of the note, followed by continuous decrease of energy towards the note’s end. Pulses were very narrowly spaced. Numerical parameters of three analysed calls were as follows: call duration (= note duration) 594–682 ms (630.0 ± 46.1 ms); 41–46 pulses per note (43.7 ± 2.5); pulse duration 7–11 ms (8.3 ± 1.2 ms); pulse repetition rate within notes 63.8– 77.8 pulses/s (69.9 ± 4.9); dominant frequency 2497–2583 Hz (2532 ± 32 Hz), with a second peak of almost identical energy at around 880–920 Hz; prevalent bandwidth 660– 3200 Hz; call repetition rate (= note repetition rate) not identifiable with available recordings.

Variation in the advertisement call over populations of M. bellyi on Montagne d’Ambre was investigated by Rasolonjatovo et al. (2022) for 23 male specimens. In all cases, the calls typically consisted of a single note, with minor variation of call duration between individuals, and without significant differences in call parameters between sites. Dominant frequency was negatively correlated with body size.

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

Distribution. —Distributed in the North and North East of Madagascar; apparently allopatrically distributed with respect to its sister species, M. ulcerosus ( Fig. 7 ). In Montagne d’Ambre National Park (the type locality) it is well documented from across the whole elevational range of the mountain. Additionally, our genetic results confirm its presence in Ankarana, Fanambana forest, Andrakata, Marojejy, Montagne des Français, Belambo, Andapa, and Andrafainkona/Ambarata. Elevation range: 53–1372 m a.s.l.

Etymology.— Eponym for a ‘Mr Belly’ according to the original description, who collected the type specimens. This probably refers to Édouard Belly, to whom Charles A.Alluaud referred as ‘adjoint à ma mission par le Muséum de Paris’ for his travels in northern Madagascar ( Alluaud 1893).

Figures

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 26. Mantidactylus bellyi in life, in dorsolateral and ventral view. (a,b)Adult male from Montagne d’Ambre, photographed in 2000. (c,d)Adult male from Montagne d’Ambre, photographed in 2004. (e,f)Adult male from Montagne d’Ambre, photographed in 2003. (g,h) Adult female from Montagne d’Ambre, photographed in 2003. (i,j) Adult female from Montagne d’Ambre. (k) Adult specimen (unsexed) from Andapa. (l,m,n,o) Two adult males from Montagne des Français, photographed in 2004. (p,q,r,s). Two adult males from Ankarana, photographed in 2003.

FIGURE 27. Mantidactylus bellyi from Montagne d’Ambre in life, all photographed in 2017–2018. (a,g) Adult male specimens tissue-sampled and included in molecular analysis (SRTIS numbers). (b) Unsexed adult (MSZC 0557, voucher deposited in UADBA). (c) Adult male (ZSM 39/2018 = MSZC 0751). (d) Adult female (MSZC 0616, voucher deposited in UADBA). (e) Adult female (ZSM 37/2018 = MSZC 0490). (f) Adult male (not collected). (h) Adult female (MSZC 0402, voucher deposited in UADBA).

FIGURE 28. Audiospectrogram and corresponding oscillogram of one advertisement call of Mantidactylus bellyi, recorded on 17 March 2000 at the entrance of the Montagne d’Ambre National Park (21.6°C air temperature). Recording bandpass-filtered at 460–8000 Hz.