Mantidactylus jahnarum, 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 : 247-250

Mantidactylus jahnarum sp. nov.

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.

Holotype.— ZSM 423/2006 ( ZCMV 3390 ), adult male (call voucher), collected by M. Vences and J.E. Randrianirina on 7–8 March 2006 at Maromandia village on Nosy Boraha (16.9089°S, 049.8678°E, 20 m a.s.l.), Analanjirofo Region, Madagascar. 16S and cox1 barcode sequences of the holotype are available from GenBank (accessions FJ559258 and JN133220 ).

Paratypes.—A total of three paratypes: ZSM 424/2006 ( ZCMV 3393 ), adult male, with same collection data as holotype; ZSM 520/2006 ( ZCMV 3218 ) and ZSM 521/2006 ( ZCMV 3219 ), two adult females, collected by M. Vences and J.E. Randrianirina on 7–8 March 2006 in a forest several km from Maromandia village (coordinates not taken), Nosy Boraha (= Île Sainte Marie) .

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.

Description of the holotype.—Adult male in good state of preservation ( Fig. 48 ). Part of right thigh muscle removed as tissue sample; femoral glands partly detached for examination in internal view. Body relatively slender.

Head as wide as body. Snout rounded. Nostrils directed laterally, slightly protuberant. Nostrils nearer to tip of the snout than to eye. Canthus rostralis weak, rather straight.

Loreal region concave. Tympanum distinct, large, slightly wider than high, its horizontal diameter about 75% of eye diameter. Supratympanic fold present, beginning straight, with a rather distinct bend midway towards jaw / forelimb insertion. Tongue ovoid, distinctly bifid. Maxillary teeth present. Vomerine teeth present in two 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 slightly shorter than tibia (97%). Lateral metatarsalia separated.

Inner and outer metatarsal tubercles present. Webbing formula: 1(0.5), 2i(1.5), 2e(0), 3i(1.5), 3e(1), 4i(2), 4e(2), 5(0.5). Relative length of toes: I<II<V=III<IV. Skin on the upper surface quite smooth in preservative with some granules on the lower flanks (but rather tubercular in life). Ventral side smooth. Femoral glands present, with a distinct and large distal ulcerous macrogland, internally consisting of four large granules. Proximal granular gland field not recognisable.

Colour in preservative: dorsum uniformly dark brown.

Very weak signs of crossbands on fore- and hindlimbs.Venter dark grey, chest and throat rather dark brown with distinct light spots which form an interrupted and indistinctly marked central median line on throat. In life, colour of the holotype was similar to preservative, with a somewhat lighter tone of brown dorsally and a more whitish venter.

Variation.—Variation in measurements is given in Table 8. See Fig. 53 for colouration in life and its variation.

There is moderate sexual size dimorphism (confirmed male SVL 28.5–30.3 mm [n = 2] vs confirmed female SVL 30.4–33.6 mm [n = 2]). Also, sexual dimorphism in relative tympanum size seems to be absent (HTD/ED ratio is 62– 73% in females, 69–70% in males). Femoral glands in life are rather distinct and prominent in males, with a large distal ulcerous macrogland, often with a somewhat yellowish colour but still with some of the dark pigmentation found elsewhere on the ventral side of the thigh.

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.

Distribution.— Apparently microendemic to the islet of Nosy Boraha ( Fig. 7 ), although a related lineage provisionally assigned to this species occurs on the adjacent mainland. Elevation range: ~ 20 m a.s.l.

Etymology.—We dedicate this species to our microbiologist colleagues Martina and Dieter Jahn, in recognition of their support of biodiversity research at the University of Technology in Braunschweig. We intentionally deviate from Article 31.1.2 of the Code and form the name using the feminine plural ending -arum, and not the masculine plural ending, -orum, with the intention of drawing attention to the already overly maledominated taxonomic nomenclature, and the desire for a more egalitarian declension. To stabilise the nomen as coined here, we define it as a noun in apposition.

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 48. Preserved holotype specimens of newly named species in the Mantidactylus fergusoni clade. Scale bars equal 5 mm.

FIGURE 53. Mantidactylus jahnarum sp. nov. in life, in dorsolateral and ventral view. (a,b,c) Adult male (holotype ZSM 423/2006) from Nosy Boraha, photographed in 2006. (d) Unsexed specimen from Nosy Boraha, photographed in 1991. (e,f) Adult male from Nosy Boraha, photographed in 1991.

FIGURE 54. Audiospectrogram and corresponding oscillogram of one advertisement call of the holotype of Mantidactylus jahnarum, recorded on 7 March 2006 at Maromandia village, Nosy Boraha. Recording bandpass-filtered at 500–6500 Hz.