Mantidactylus kortei, 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 : 233-235

Mantidactylus kortei sp. nov.

Identity and justification.—This lineage has only been found at high elevations of the Andohahela Massif, in a swamp and along streams. In previous DNA barcoding assessments, it has been considered as M. sp. 30 by Vieites et al. (2009) and M. sp. Ca30 by Perl et al. (2014). It is sister to M. noralottae from Isalo in the phylogenomic analysis (but according to 16S data may also be closely related to M. riparius sp. nov. which is not represented in the phylogenomic analysis; see below). However, it differs from M. noralottae in advertisement call and morphology (e.g. smaller body size; Table 4 ), and from its two siblings by a high genetic divergence (≥4.3% from M. noralottae , and ≥5.9% from M. riparius sp. nov.), supporting its species status. Some individuals of M. kortei sp. nov. are characterized by a relatively short snout, but this is apparently not the case in all individuals.

Holotype.— ZSM 205/2005 ( FGZC 2376 ), adult male, collected by P. Bora, F. Glaw, and M. Vences on 26 January 2005 near camp, Andohahela (24.5440°S, 046.7141°E, 1548 m a.s.l.), Anosy Region , Madagascar.

A 16S barcode sequence of the holotype was obtained in this study and was included in the analysis.

Paratypes. —A total of three paratypes : ZSM 203/2005 ( FGZC 2377 ) and ZSM 204/2005 ( FGZC 2375 ), two adult females with the same collection data as the holotype; ZSM 195/2005 ( FGZC 2480 ), an adult female, collected by F. Glaw, M. Vences, and P. Bora on 28 January 2005 in a stream at high elevation, Andohahela (ca 24.544°S, ca 046.714°E, ca 1650 m a.s.l.) .

Diagnosis.— Mantidactylus kortei sp.nov. is a member of the M. betsileanus clade and related to M. noralottae in the phylogenomic analysis. See Table 4 for a list of diagnostic morphological characters. The combination of a relatively small body size (male SVL 27 mm), slightly tubercular dorsal skin with distinct continuous dorsolateral ridges, relatively large tympanum (13% of SVL in males), presence of a white marking on the snout tip in most specimens, and advertisement call consisting of a single pulsed note not repeated in regular series distinguishes M. kortei sp. nov. from species of all other clades. Species of the M. fergusoni clade are larger and have typically a more tubercular dorsum, while species of the M. curtus clade are often larger and most have a smaller tympanum.

Some specimens of the new species have whitish dots on the flanks and only an indistinct white marking on the snout tip, which impedes their distinction from some species of the M. biporus , M. stelliger and M. inaudax clades where advertisement calls are unknown. However, the usually more pointed snout, larger tympanum, longer limbs, and overall different appearance of M. kortei sp. nov. should make a distinction straightforward ( Table 4 ). Within the M. betsileanus clade, the new species can be distinguished from M. betsileanus , M. noralottae and M. tripunctatus by having fewer pulses per note in advertisement calls; furthermore from M. noralottae by smaller body size. Mantidactylus katae has a different advertisement call structure and larger femoral glands; M. jonasi has typically more pulses per note in advertisement calls, a slower pulse repetition rate, and a more tubercular dorsum; and M. incognitus has more expressed dorsal and dorsolateral ridges and supraocular tubercles ( Table 4 ).

For a detailed 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. kortei 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. 33 ). Tissue sample taken ventrally from right thigh.Femoral gland partly detached to examine their structure internally. Body rather slender. Head wider than body. Snout rounded in dorsal view, truncate in lateral view. Nostrils directed laterally, slightly protuberant.

Nostrils nearer to tip of the snout than to eye. Canthus rostralis weak, slightly concave. Loreal region slightly concave. Tympanum distinct, large, elliptical, wider than high, its diameter 88% of eye diameter. Supratympanic fold distinct, beginning straight, with a distinct, angular 90° bend midway towards insertion of forelimb. Tongue ovoid, distinctly posteriorly bifid. Maxillary teeth present. Vomerine teeth distinct in elliptical 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 longer than tibia (110%). Lateral metatarsalia separated. Inner metatarsal tubercle present. Outer metatarsal tubercle small but recognisable. Webbing formula: 1(0.25), 2i(1.5), 2e(0.5), 3i(1), 3e(0.5), 4i(2), 4e(2), 5(0.5). Relative length of toes: I<II<V=III<IV. Skin on the upper surface smooth, granular on flanks, with relatively well recognisable dorsolateral folds (distinct in life). Ventral side smooth. Femoral glands present, and distinct, the distal ulcerous macrogland consisting of five large granules with an external central depression, and with a moderately expressed proximal granular gland field, particularly visible in internal view.

Colour in preservative: dorsum brown, with indistinct irregular darker markings and some white spotting on flanks and with poorly contrasted crossbands on limbs. Loreal region light brown with dark markings. Snout tip with a distinct light dot. Venter beige, throat and chest with brown mottling. Lower lip ventrally with alternating light and brown spots. Colour in life similar to that in preservative, but more contrasted.

Variation.—Variation in measurements is given in Table7.See Fig.44 for colouration in life and its variation. There may be pronounced sexual size dimorphism, but sample sizes are low (confirmed male SVL 27.4 mm [n = 1] vs confirmed female SVL 34.6–37.1 mm [n = 3]).

Males may have a slightly larger tympanum than females (HTD/ED ratio is 73–80% in females, 88% in the male). Femoral glands in males are relatively prominent, but not prominently coloured in life, at least not in the only male available for examination.

Natural history.—Calls of a large number of males were heard during the day, after heavy cyclonic rainfall from a sun-exposed swamp area in grassland directly next to primary rainforest. Several specimens were also found next to small streams in rainforest.

Calls. —The advertisement call of M. kortei , recorded on 27 January2005 atAndohahela National Park (specimens not seen calling, therefore attribution of calls not completely certain, but very likely), 17.6°C air temperature ( Vences et al. 2006: CD2, track 78), consists of a pulsed note ( Fig. 45 ), emitted in series at irregular intervals and slow succession. Notes exhibited slight amplitude modulation, with maximum call energy occurring either during the first third of the note’s length or at the centre of the note, and the terminal pulse of the note always containing the lowest energy. In some calls, initial pulses were separated by longer inter-pulse intervals, whereas the 3-5 terminal pulses of all calls are narrowly spaced and have very short interpulse intervals. Numerical parameters of nine analysed calls, corresponding to at least two different individuals, are as follows: call duration (= note duration) 254–511 ms (356.9 ± 94.5 ms); 12–27 pulses per note (18.9 ± 4.6); pulse duration 3–6 ms (4.4 ± 0.8 ms); pulse repetition rate within notes (excluding narrowly spaced terminal pulses) 29.0–69.0 pulses/s (47.9 ± 10.1); dominant frequency 1123–1399 Hz (1224 ± 124 Hz); prevalent bandwidth 750–3200 Hz; call repetition rate (= note repetition rate) ca 4–11 calls/min.

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

Distribution.— Apparently microendemic to high elevations in Andohahela National Park ( Fig. 7 ). Elevation range: ~ 1548 m a.s.l.

Etymology.—We dedicate this species to Martin Korte, cellular neurobiologist of Braunschweig University of Technology, in recognition of his continued support of our research activities over the past 15 years.

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 33. Preserved holotype specimens of newly named species in the M. betsileanus clade. Scale bars equal 5 mm.

FIGURE 44. Mantidactylus kortei sp. nov. from Andohahela in life, in dorsolateral and ventral view. All photographs taken in 2005. (a,b) Adult male (holotype ZSM 205/2005 = FGZC 2376). (c,d) Adult female (ZSM 204/2005 = FGZC 2375). (e) Female specimen (probably preserved in UADBA). Note the relatively broad and short head of the first two specimens and the more pointed head of the third specimen in (e) which however showed no difference to the other two specimens in the molecular markers analysed.

FIGURE 45. Audiospectrogram and corresponding oscillogram of one advertisement call tentatively assigned to Mantidactylus kortei, recorded on 27 January 2006 at Andohahela National Park (17.6°C air temperature). Recording bandpass-filtered at 500– 4000 Hz.