Bioacoustics of Mantidactylus noralottae

Identity .—This species is genetically defined by the sequences of various paratypes published in the original description (MRSN A5252 and A5254; SMF 85861‒SMF 85864 corresponding to previous MRSN A5253 and A5255‒A5257; Mercurio & Andreone 2007 ). Unfortunately, no genetic data are available for the holotype or the call voucher paratype , MRSN A5317. However, both the holotype and the call voucher are comparatively large-sized individuals of 34.8 and 33.4 mm SVL, respectively, and thus distinctly larger than the second species of the M. betsileanus clade occurring at Isalo (described below as M. riparius sp. nov. ). Furthermore, according to measurements in Mercurio & Andreone (2007) and here reproduced in Table 7 , the male holotype of M. noralottae has a smaller relative tympanum size and smaller femoral glands than the third species of Brygoomantis at Isalo, M. mahery (see above and Tables 4‒5 ), confirming the holotype of M. noralottae is conspecific with the paratypes and other individuals usually assigned to this taxon.

Diagnosis .—A member of the M. betsileanus clade as revealed by the phylogenomic analysis, sister to M. kortei sp. nov. described below. See Table 4 for a list of diagnostic morphological characters. The combination of a moderate body size in males (SVL 33–36 mm ) and distinctly larger size in females (SVL 36–40 mm ), rather smooth to slightly tubercular dorsal skin with distinct continuous dorsolateral ridges, relatively large tympanum (10–12% of SVL), absence of white spots on flanks, absence of a white marking on snout tip, and advertisement call consisting of a single, long note composed of ≥90 pulses distinguishes M. noralottae from species of all other clades ( Table 4 ); M. noralottae may appear superficially similar to some species of the M. curtus clade but these have a smaller tympanum and less pulses in advertisement calls. Within the M. betsileanus clade, the species differs from all species except M. betsileanus (for M. incognitus sp. nov. calls are unknown) by a higher number of pulses in advertisement calls ( Table 4 ); it differs from these two species by larger body size of males, and from M. betsileanus also by fewer pulses in advertisement calls ( Table 4 ). For a detailed distinction from its sister species M. kortei sp. nov. , from the sympatric M. riparius sp. nov. , and from all other new species described herein, see the respective species accounts. A full list of molecular diagnostic sites in the 16S gene of M. noralottae in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Calls .—The advertisement call of M. noralottae , recorded on 18 December 2004 , 20:00 h, at Ambovo, Isalo National Park, 20°C air temperature (from paratype MRSN A5319), consisted of a very long, regularly pulsed note ( Fig. 37 ), emitted in irregular series. Each note showed some significant amplitude modulation with call energy slowly increasing to approximately the middle of the note’s duration and then slowly decreasing towards its end. Numerical parameters of five analysed calls were as follows: call duration (= note duration) 2054–2705 ms (2411.4 ± 273.9 ms); ca 92–108 pulses per note (100.6 ± 7.1); pulse duration 9–15 ms (10.9 ± 1.6 ms); pulse repetition rate within notes 37.4–41.2 pulses/s (39.7 ± 1.3); dominant frequency 1345–1405 Hz (1370 ± 26 Hz); prevalent bandwidth 1200–2100 Hz; call repetition rate (= note repetition rate) ca 12 calls/min. Tadpoles.— The tadpole of this species has not been described.

Diagnosis . A species attributed to the genus Mantidactylus based on the following characters (1) presence of femoral glands of type 3, smaller in females, (2) presence of a single subgular vocal sac, and (3) absence of nuptial pads in males. This species is included in the subgenus Brygoomantis due to genetic and bioacoustics evidence. Further morphological characters are: body medium sized; tympanum of males distinctly larger than those of females; tibiotarsal articulation reaches between eye and nostrils; metatarsalia separated; toes webbed; fingertips moderately enlarged; and males with single, subgular vocal sac. Distinction from other species of Brygoomantis is mainly based on the isolated distribution and molecular relationships of the new species (see below).

Morphological comparison with other species . Based on the basis of genetic and bioacoustics evidences Mantidactylus noralottae has been placed in the subgenus Brygoomantis . However, like the other species belonging to this subgenus superficial similarities are shared with the species belonging to subgenus Ochthomantis . Convincing synapomorphies on adult morphology able to clearly cut species belonging to both subgenera are currently unknown ( Glaw & Vences, 2006 ). In particular, at the Isalo Massif M. noralottae lives in sympatry with M. sp. aff. ulcerosus (Boettger) and in syntopy with M. cf. femoralis (Boulenger) . Adults of M. noralottae can be confused with juveniles of M. cf. femoralis and, at a lesser extent, with adult specimens of M. sp. aff. ulcerosus . Mantidactylus noralottae can be distinguished from M. sp. aff. ulcerosus by: (a) different dorsal colouration (brownish softly spotted vs. uniformly light brown to greyish sometimes with darker patches; (b) dorsal skin (smooth vs. granular); (c) general overall appearance (slender vs. stout); (d) advertisement call (single prolonged note vs. 8–14 notes). It can be distinguished from the other Brygoomantis species by the following combinations of characters: body dimension (smaller in M. alutus (Peracca) , M. biporus (Boulenger) , M. tricinctus (Guibé) , and larger in M. ambohimitombi Boulenger ); by dorsal colouration and presence of vomerine teeth ( M. madecassus Millot & Guibé and M. pauliani Guibé ); by dorsal skin texture and hind limb length (skin granular in both M. betsileanus and M. curtus , hind limbs comparatively longer in the first and shorter in the second); and by different advertisement calls (from the recently resurrected taxa M. bellyi Mocquard and M. bourgati Guibé ). Convincing differences in call parameters between M. noralottae and M. betsileanus are still in need of identification, largely depending on an upcoming taxonomic revision of the subgenus Brygoomantis . Mantidactylus noralottae can be distinguished from the syntopic M. cf. femoralis by: (a) different dorsal colouration (lighter without black stripes and yellow spot on flanks vs. darker with presence of black stripes and yellow spot on flanks), (b) different ventral colouration (slightly marbled on chest, belly dirty without black lines on throat vs. heavily marbled, belly spotted, black lines on throat often present), (c) hind limbs length (tibiotarsal articulation reaches between eyes and nostrils vs. tip of snout or beyond); d) body size ( 34.1 mm , males, and 37.7 mm , females vs. 37.8 mm , males, and 44.7 mm , females) and, (e) body shape (slender vs. quite stout). Mantidactylus noralottae can be distinguished from the other species belonging to the Ochthomantis subgenus ( M. ambreensis Mocquard , M. majori Boulenger , M. mocquardi Angel and M. zolitschka Glaw & Vences ) by: (a) dorsal colouration uniformly brownish more or less spotted, (b) dorsal skin smooth, (c) smaller body size (male SVL < 40 mm vs.> 40 mm except for M. ambreensis ) and (d) comparatively enlarged inner metatarsal tubercle, (e) advertisement call. Mitochondrial differentiation. Accession numbers of newly obtained sequences: MRSN A5252, EF222306 ; SMF 85861, EF222307 ; MRSN A5254, EF222308 ; SMF 85862, EF222309 ; SMF 85863, EF222310 ; SMF 85863, EF222311 . The uncorrected pairwise DNA divergence of the Mantidactylus noralottae 16S rRNA gene sequence compared to that of M. betsileanus from Mandraka ( East Madagascar ) is 3.6 %, while the difference with M. ulcerosus from Berara (NW Madagascar ) corresponds to 11.5%–11.9% ( M. Vences , pers. comm.). This divergence fully supports the specific status of M. noralottae .

Natural history . Mantidactylus noralottae is known for the Isalo Massif only. We found several individuals inside a narrow canyon in the initial and gully tracts (Mercurio & Andreone, 2006 ). Calling males were hanging at night on the almost vertical canyon walls at about 150–200 cm above the bottom or the water surface. Females and males were also found on the canyon bed inside the water pools. As far as known, M. noralottae is the only species ascribed to the subgenus Brygoomantis with such scansorial habits. They are able to climb almost vertical walls. After the dissection of six specimens to check the stomach contents we found 55 prey items divided as follows (number of prey item/percentage of the sampling): Hymenoptera , Formicidae (33, 60.0%); Coleoptera (16, 29.1%); Diptera (3, 5.4%); Aranea (1, 1.8%); Hymenoptera , undetermined (1, 1.8%); and Orthoptera (1, 1.8%). Mantidactylus noralottae Mantidactylus betsileanus Locality Ambovo, Isalo Massif Mandraka Air temperature 20°C 23-24°C Notes per call 1 1 Note duration (ms) 2400-2900 (2660 ± 221, n = 5) 2900-3100 (3053 ± 82.1, n = 4) Intervals between notes 5000-7000 (6000 ± 1414, n = 2) 11900-13000 (12660 ± 577.1, n = 3) Pulses per note 90-100 (96.6 ± 1.4, n = 5) 163-178 (172.5 ± 6.5, n = 4) Pulse duration (ms) 10-26 (15.8 ± 3.3, n = 25) 6-8 (6.8 ± 0.8, n = 15) Intervals between pulses (ms) 8-16 (12.5 ± 2.2, n = 17) 8-10 (9.1 ± 0.9, n = 10) Pulse repetition rate (1/s) 41-45 (43 ± 1.8, n = 5) 55-64 (58.6 ± 4.7, n = 3) Frequency (Hz) 900-3000 400-5000 Dominant frequency (Hz) 1300-1500 1400-1500 Mantidactylus sp. aff. ulcerosus Locality Ranohira, Isalo Massif Air temperature 23.4°C Notes per call 8-(14) Note duration (ms) 113-142 (126.3 ± 8.8, n = 8) Intervals between notes 130-170 (152.1 ± 8.4, n = 7) Pulses per note 22-26 (24.8 ± 1.3, n = 8) Pulse duration (ms) 1-10 (4.5 ± 2.3, n = 35) Intervals between pulses (ms) None Pulse repetition rate (1/s) 96-102 (99 ± 3, n = 2) Frequency (Hz) 700-4500 Dominant frequency (Hz) 1000-1200 Advertisement call . Calling male MRSN A5319 recorded at Ambovo, Parc National de l’Isalo (on 18 December 2004 , 20:00, 20°C). The call consisted of a single long note (2.6 sec) composed of a train of about 100 short pulses ( Fig. 5 , table 4). The pulse train originates during expiration and is associated with a strong vibration of the body wall. Pulses are poorly toned and harmonics are not clearly visible in the spectrogram. Fundamental frequency is around 1000 Hz while dominant frequency is about 1400 Hz. Frequency ranges from 900 to 3000 Hz. The calls are emitted after rather long time intervals (6 sec).

Description of the holotype . Male specimen in good state of preservation. Snout-vent length 35 mm , for other measurements see table 2. Body slender; head longer than wide; snout pointed in dorsal view, rounded in lateral view; nostrils directed laterally, protuberant, nearer to tip of snout than eye; canthus rostralis distinct, straight; tympanum distinct, elliptical, 81.6% of eye diameter; supratympanic fold distinct, regularly curved; tongue ovoid, posteriorly bifid; maxillary and vomerine teeth present; choanae elliptical. Arms slender; fingers without webbing; distinct single subarticular tubercle; finger discs distinctly enlarged, elliptical. Hind limbs slender, tibiotarsal articulation reaches between eye and nostrils; lateral metatarsalia separated; inner metatarsal tubercles distinct, outer absent; webbing between toes: 1(1), 2i(1), 2e(0), 3i(1.5), 3e(0.75), 4i(1), 4e(1), 5(0). Dorsal skin smooth without dorsolateral folds. Ventral skin smooth on throat, chest and belly. Femoral glands of type 3 with presence of the “structure B” very distinct from external view, overall appearance of glands very granular, 7.6 mm length and 4.2 mm width; from internal view left gland elliptical of 2.2 mm length, with 8 granules of 0.7 mm diameter. Dorsal colouration brownish softly spotted especially on the canthal region and behind the eyes. Tympanic area brownish bordered by a darker supratympanic fold. Faint darker crossbands present on arms and limbs. Ventrally whitish spotted with irregular brownish markings especially on throat, chest, hands and feet. Vocal sac single, subgular, and slightly distensible. After one year in preservative the chromatic pattern are the same as in life but with faded colours. Gephyromantis azzurrae Gephyromantis corvus Locality Sakamalio Ambovo Air temperature 22°C 20°C Notes per call 15-21 (18 ± 4.2, n = 2) 10-14 (11.5 ± 1.7, n = 4) Note duration (ms) 290-340 (299 ± 12.8, n = 15) 252-293 (281 ± 8.0, n = 10) Intervals between notes 500-740 (573 ± 92.5, n = 14) 513-716 (580.8 ± 50, n = 9) Sub-units per note 7-10 (8.1 ± 1.1, n = 15) Non-identifiable Sub-unit duration (ms) 5-147 (31.5 ± 35, n = 32) - Intervals between sub-units (ms) 1-8 (4.7 ± 1.67, n = 32) - Sub-unit repetition rate (1/s) 7-9 (8 ± 0.8, n = 7) - Frequency (Hz) 800-6500 700-5200 Dominant frequency (Hz) 3000-3200 2400-2700 Variation . The paratypes largely agree with the holotype in morphology and colouration. Chromatic differences lie in: a) presence of a lighter vertebral band; b) extension of darker pigmentation on tympanum; and c) extension and pattern of pigmentation on snout. MRSN A5254 presents a more contrasted dorsal colouration with well defined crossbands on limbs, a light vertebral band, a well defined lighter triangular shaped spot on snout extending to anterior part of eyes, and a darker tympanic area. MRSN A5319 is similar in colouration to the holotype but differs in having a more contrasted light triangle on snout. MRSN A5035 and A5252 are also similar to the holotype but they have a darker tympanic area, as well as SMF 85863 and 85864. SMF 85863 lacks the left foot maybe due to predation. Femoral glands are well defined and visible from external view in all the male specimens, reduced in form of small circular gland of about 1.0 mm diameter composed by a single flattened granule in females.