Mantidactylus biporus ( Boulenger, 1889 )

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 : 263-265

Mantidactylus biporus ( Boulenger, 1889)

Type material.—According to Blommers-Schl̂sser and Blanc (1991), Rana biporus Boulenger, 1889 is based on syntypes BMNH 1947.2.26.46–52 from ‘ Madagascar’. We here designate BMNH 1947.2.26.47 , an adult female from which we could obtain a DNA sequence, as lectotype. Lectotype designation is justified by the need to stabilize this and other nomina in Brygoomantis , given the uncertain identity and morphological similarity of many taxa in the subgenus.

Identity.—Consideringthelargenumberofgenetically highly divergent lineages conforming at least roughly to the morphology of M. biporus , and the lack of a precise type locality, the identity of this nomen has long remained obscure. Using barcode fishing we obtained a sequence of the lectotype which clusters with specimens of a previously ( Perl et al. 2014; Vieites et al. 2009) unreported lineage found in Betampona as well as in An’Ala, allowing us herein to newly ascribe this name to that lineage. The lineage previously ( Vieites et al. 2009) assigned to M. biporus is reassigned to M. inaudax below. It is worth mentioning that in the original description ( Boulenger 1889), the species was described as ‘ Rana biporus ’, and the species epithet may have been meant as a noun in apposition, making the emendation ‘ Rana bipora ’ (e.g. Blommers-Schl̂sser & Blanc 1991; Guibé 1978) unjustified (see also Frost 2021). However, given the species is now in the genus Mantidactylus (of masculine gender) this has no bearing on the name Mantidactylus biporus as currently used. The species has been previously referred to as Mantidactylus sp. aff. biporus [Ca HM364733 ] (sp. Ca76) by Rosa et al. (2011, 2012).

Synonyms.—Previously Mantidactylus brauni Ahl, 1929 was considered a synonym, but we have shown here that that nomen is a junior synonym of M. ulcerosus .

Reference specimens. — ZSM 1982/2006 ( ZCMV 2425 ), adult male, and ZSM 396/2006 ( ZCMV 1483 ), adult female, collected by D.R. Vieites, M. Vences, F. Rabemananjara, P. Bora, C. Weldon, and J. Patton on 07– 19 February 2006 at An’Ala (forest camp) (18.91926°S, 048.48796°E, 889 m a.s.l.); MRSN A6180 ( FAZC 13480 ), adult male, collected by G.M. Rosa on 4 February 2007 at Sahabefoza in Betampona (17.9142°S, 049.2077°E, 349 m a.s.l.); MRSN A6266 ( FAZC 13675 ), adult male, collected by G.M. Rosa on 27 February 2007 at Vohitsivalana in Betampona (17.8862°S, 049.2025°E, 517 m a.s.l.); MRSN A6374 ( FAZC 13835 ), adult male, collected by G.M. Rosa on 29 October 2007 at Sahabefoza in Betampona (at geographical coordinates 17.91438°S, 49.20778°E, 325 m a.s.l); ZSM 184/2021 ( ACZCV 201 = ACZC 5694 ), putative female, collected on 14 November 2013 at Vohitsivalana, Betampona (17.8862°S, 049.2026°E), by A. Crottini, D. Salvi, E. Scanarini, Georges, and Jean Noël.

Diagnosis.—A member of the M. biporus clade, sister to the new species M. augustini sp. nov. (described below) according to our phylogenomic analysis. See Table 4 for a list of diagnostic morphological characters. The combination of a moderate body size (male SVL 28- 32 mm, female SVL 31–36 mm [one probably immature female 19.3 mm]), rather smooth dorsal skin without dorsolateral ridges, moderate to relatively large tympanum size in males (10–12% of SVL), presence of white spots on flanks, absence of a white marking on the snout tip, and a short, pulsed advertisement call emitted in rapid succession in regular series, distinguishes M. biporus 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 larger tympanum in males, and a lower pulse repetition rate in advertisement calls. Mantidactylus biporus is distinguished from its sister species M. augustini sp. nov. by larger body size, smaller tympanum, shorter hindlimbs, less pulses per note and higher pulse rate in advertisement calls. For a distinction from the other (all 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. biporus in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Variation.—Variation in measurements is given in Table10. See Fig. 63 for colouration in life and its variation. A light vertebral line can be present. There is weak sexual size dimorphism (confirmed male SVL 28.0– 31.6 mm [n = 5] vs confirmed female SVL 30.5–35.8 mm [n = 2]; one further female, ZSM 184/2021, measures only 19.3 mm but we hypothesize it is an immature specimen). Males have a slightly larger tympanum than females (HTD/ED ratio is 60–70% in females, 69–79% in males). Femoral glands of males in life are not documented. Females, both in preservative as in life ( Fig. 63c ) have a distinct pattern of two distinct gland rudiments next to each other which almost certainly explains the species name.

Natural history.—Males call during the day and night from flooding zones of small forest streams.

Calls.— The advertisement call of M. biporus recorded at Betampona on 31 October 2007 at 20:00 h, 19°C air temperature ( Rosa et al. 2011: track 34), consisted of a short, regularly pulsed note ( Fig. 64 ), emitted in regular series at very fast succession. Slight amplitude modulation was present, with relative amplitude increasing from the beginning of the call, reaching its maximum approximately at the last third of the note’s duration. Calls in call series tended to become louder and longer from the beginning to the end of a series. Numerical parameters of 45 analysed calls of two individuals were as follows: call duration (= note duration) 93–132 ms (109.7 ± 11.2 ms); 15–21 pulses per note (17.4 ± 1.8); pulse duration 4–5 ms (4.7 ± 0.5); pulse repetition rate within notes 130.4–210.5 pulses/s (165.8 ± 27.9); dominant frequency 832–997 Hz (884 ± 61 Hz); prevalent bandwidth 400–3000 Hz; call repetition rate (= note repetition rate) within regular series ca 300–360 calls/min. Call series (n = 4) had a duration of 2290–5875 ms.

Tadpoles.— The tadpole of this species has not been described. The tadpole described under this name by Knoll et al. (2007) refers to M. inaudax bona species, see below.

Distribution.— Endemic to low-elevation rainforest in the Northern Central East ( Fig. 7 ). This species is known from An’Ala and Betampona. The type locality cannot currently be narrowed down. Elevation range: 190–840 m a.s.l.

Etymology.— Latin noun in apposition meaning ‘double pores’, presumably in reference to the femoral glands of this species where especially in females, two separate gland rudiments are visible.

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 63. Mantidactylus biporus from Betampona in life, in dorsolateral and ventral view. (a) Adult male, MRSN A6374 (FAZC 13835). (b,c) Adult female (FAZC 13957). (d) Unsexed specimen (ACZC 5694). (e) Adult female (FAZC 13552). (f) Adult male (FAZC 13620). Note the eponymous pair of small pores visible on the ventral thigh in (c).

FIGURE 64. Audiospectrogram and corresponding oscillogram of a 1000 ms section of a series of advertisement calls (five calls figured) of Mantidactylus biporus recorded on 31 October 2007 at Betampona (19°C air temperature).