Bioacoustics of Mantidactylus jahnarum

Diagnosis .— Mantidactylus jahnarum sp. nov. is a member of the M. fergusoni clade as revealed by the phylogenomic analysis, and is the sister species of M. fergusoni . See Table 4 for a list of diagnostic morphological characters.The combination of a moderate body size (male SVL 29–30 mm , female SVL 30–34 mm ), moderately tubercular dorsal skin, moderate tympanum size in males (11% of SVL), absence of white spots on flanks, presence of a white marking on the snout tip of many individuals (especially males), and regularly pulsed advertisement call emitted in regular series distinguishes M. jahnarum sp. nov. from most species of the other clades ( Table 4 ). Two species from the M. ulcerosus clade ( M. ulcerosus and M. bellyi ) can be morphologically similar, but they occur in the Sambirano and North West regions, and have higher pulse repetition rates in advertisement calls ( Table 4 ). Mantidactylus jahnarum sp. nov. shows similarities to species of the M. betsileanus clade but does not appear to occur sympatrically with any of them; in general, it has a more tubercular dorsum and differs from most of these by advertisement call structure ( Table 4 ). Within the M. fergusoni clade, it differs from M. fergusoni and M. georgei in advertisement call structure: M. fergusoni has single-pulse calls repeated 2–5 times per second, whereas M. georgei does not arrange calls in regular series. For a distinction from other new species described herein, see the respective species accounts. A full list of molecular diagnostic sites in the 16S gene of M. jahnarum sp. nov. in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Natural history .—Similar to M. georgei , this species appears to tolerate heavy habitat degradation. At Nosy Boraha, it can be found next to streams in rainforest, but calling males can also be heard at night from slowly running, shallow water bodies in highly degraded forest, including plantations and swamps next to villages shaded by some larger trees. Calls.— The advertisement call of M. jahnarum , recorded on 7 March 2006 at Maromandia village, Nosy Boraha, from the holotype , at an at 25°C, consisted of a regularly pulsed note of variable duration ( Fig. 54 ), emitted in series at regular intervals. Pulses were very short in duration. Regular call series seemed to consist of 4–6 calls, with the first call of the series being of longest duration. Notes exhibited slight amplitude modulation, with maximum call energy occurring shortly after the beginning of the note, continuously decreasing towards the note’s end. Numerical parameters of 20 analysed calls were as follows: call duration (= note duration) 568–1558 ms (976.9 ± 277.9 ms); 16–45 pulses per note (29.1 ± 7.9); pulse duration 1–2 ms (1.1 ± 0.3 ms); pulse repetition rate within notes 25.0–35.4 pulses/s (29.3 ± 3.9); dominant frequency 2971–3120 Hz (2999 ± 60 Hz); prevalent bandwidth 1000–3400 Hz; call repetition rate (= note repetition rate) within regular series ca 36-47 calls/min. Tadpoles.— The tadpole of this species has not been described.

Identity and justification .—This lineage of the M. fergusoni clade has previously considered as confirmed candidate species M. sp. 27 by Vieites et al. (2009) , and M. sp. Ca27 by Perl et al. (2014) . It was depicted as ‘ Mantidactylus sp. aff. betsileanus “Nosy Boraha”’ by Glaw and Vences (2007) . The phylogenomic data place it sister to M. fergusoni , and its mitochondrial divergence from M. fergusoni (2.0–3.1%) is comparatively low, compared with other divergences observed among species of Brygoomantis . However, it distinctly differs by its advertisement calls (heard in multiple years from many individuals at the type locality, the islet Nosy Boraha) that consists of several short, pulsed notes, somewhat reminiscent of the call of species of the M. ulcerosus clade. We therefore here consider this lineage as the separate species M. jahnarum sp. nov. which, according to genomic data, may also include populations from the mainland adjacent to Nosy Boraha which were named M. sp. Ca25 by Vieites et al. (2009) and which we here provisionally include in M. jahnarum sp. nov. as deep conspecific lineage.