Gephyromantis (Asperomantis) angano, Scherz, Mark D., Vences, Miguel, Borrell, James, Ball, Lawrence, Nomenjanahary, Denise Herizo, Parker, Duncan, Rakotondratsima, Marius, Razafimandimby, Elidiot, Starnes, Thomas, Rabearivony, Jeanneney & Glaw, Frank, 2017

Scherz, Mark D., Vences, Miguel, Borrell, James, Ball, Lawrence, Nomenjanahary, Denise Herizo, Parker, Duncan, Rakotondratsima, Marius, Razafimandimby, Elidiot, Starnes, Thomas, Rabearivony, Jeanneney & Glaw, Frank, 2017, A new frog species of the subgenus Asperomantis (Anura, Mantellidae, Gephyromantis) from the Bealanana District of northern Madagascar, Zoosystematics and Evolution 93 (2), pp. 451-466 : 455-458

Gephyromantis (Asperomantis) angano sp. n. Figures 1, 3, 4, 5, 6, 7, Suppl. material 1, 2, 5

Gephyromantis sp. Ca28 - Perl et al. (2014)

Holotype.

ZSM 68/2016 (MSZC 0172), an adult male, collected at 22h40 on 8th January 2016 in Ampotsidy (14.41949°S, 48.71938°E, 1340 m a.s.l.), roughly 15 km north of Bealanana in the Bealanana District, Sofia Region, northern Madagascar, by Mark D. Scherz, James Borrell, Lawrence Ball, Thomas Starnes, Elidiot Razafimandimby, Denise Herizo Nomenjanahary, and Jeanneney Rabearivony.

Paratypes.

ZSM 67/2016 (MSZC 0112) adult female, collected at night on 30th December 2015 in Ampotsidy (14.41734°S, 48.71858°E, 1363 m a.s.l.); ZSM 69/2016 (MSZC 0021) adult male, collected at 22h00 on 19th December 2015 in Ampotsidy (14.41956°S, 48.71946°E, 1357 m a.s.l.); UADBA-A uncatalogued (MSZC 0032) adult male, collected in the late morning on the 21st December 2015 in Ampotsidy (14.41435°S, 48.71155°E, 1431 m a.s.l.); UADBA-A uncatalogued (MSZC 0053) subadult, collected at 20h43 on 22nd December 2015 in Ampotsidy (14.41382°S, 48.71178°E, 1443 m a.s.l.); UADBA-A uncatalogued (MSZC 0091), an adult female collected at night on 30th December 2015 in Ampotsidy (14.41208°S, 48.71609°E, 1513 m a.s.l.); all collected by Mark D. Scherz, James Borrell, Lawrence Ball, Thomas Starnes, Elidiot Razafimandimby, Denise Herizo Nomenjanahary, and Jeanneney Rabearivony. ZSM 1731/2010 (ZCMV 12303), adult female, collected on 9th June 2010 on the Tsaratanana massif, in the forest near camp 0 ( Antsahan’i Ledy; 14.2332°S, 48.9800°E, 1207 m a.s.l.) by Miguel Vences, David R. Vieites, Roger-Daniel Randrianiaina, Fanomezana Ratsoavina, Solohery Rasamison, Andolalao Rakotoarison, Emile Rajeriarison, and Theo Rajoafiarison.

Diagnosis.

A Gephyromantis species assigned to the subgenus Asperomantis based on the presence of small dermal spines on the elbow and heel, presence of inner and outer dorsal ridges as defined by Vences and Glaw (2001), Type 2 femoral glands sensu Glaw et al. (2000) Glaw et al. (2000), moderately enlarged finger and toe tips, absence of webbing between fingers, moderate webbing between toes, presence of paired blackish sub-gular vocal sacs in males, and a distinct whitish spot in the middle of the tympanic field ( Vences et al. 2017). DNA sequence data from a fragment of the 16S gene supports this assignment. Gephyromantis angano sp. n. is characterized by the following suite of morphological characters: (1) adult SVL 29.1-30.5 mm, (2) TD/ED 0.61-0.71, (3) small supraocular spines, (4) large femoral glands consisting of numerous small granules, (5) moderately raised dorsal ridges, (6) granular dorsal skin, (7) relatively short hindlimbs (HIL/SVL 1.73-1.81 in males), and (7) its unique call (see above).

Within the subgenus Asperomantis , Gephyromantis angano sp. n. can be distinguished from G. ambohitra , G. spinifer , and G. tahotra by its smaller size (male SVL <30 mm, vs.>31 mm, female SVL up to 30.5 mm vs.>32 mm); from G. spinifer by its less granular dorsal skin and smaller supraocular spines; from G. asper and G. ceratophrys by its generally shorter hindlimbs in males (HIL/SVL 1.73-1.81 vs. 1.77-2.11); and from G. ceratophrys by more granules per femoral gland (26-69 vs. 14-20). Bioacoustically, it is distinguished from all of these species by its call duration (41-98 ms vs. 5-44 ms in G. asper and G. ceratophrys , and 98-274 ms in G. ambohitra and G. tahotra ), unpulsed calls (vs. pulsed in G. ambohitra and G. tahotra ), calls repeated faster than in G. ceratophrys , and dominant frequency (3703-3875 Hz vs. 1435-3366 Hz in G. ambohitra , and G. tahotra ).

Description of the holotype.

A specimen in a good state of preservation, the left thigh cut for DNA tissue sample and to expose the inner face of the femoral gland. Snout-vent length 29.6 mm. For other measurements see Table 1. Body rather rounded; head longer than wide, as wide as the body; snout acuminate in dorsal view, truncate in lateral view; nostrils directed laterally, slightly protuberant, much nearer to tip of snout than to eye; canthus rostralis distinct, concave; loreal region concave and moderately oblique; tympanum distinct, round, its diameter 71% of eye diameter; supratympanic fold distinct, curving ventrally; tongue ovoid, distinctly bifid posteriorly; vomerine teeth distinct, in two small aggregations, positioned posteromedially to choanae; choanae rounded. Dark dermal fold (the inflatable parts of the vocal sacs) running along each lower jaw from commissure of mouth to middle of lower jaw. Arms slender, subarticular tubercles single; outer metacarpal tubercle very poorly developed and inner metacarpal tubercle relatively well developed; fingers without webbing; relative length of fingers 1 <2 <4 <3, second finger dis tinctly shorter than fourth; finger discs distinctly enlarged, nuptial pads absent. Hindlimbs slender; tibiotarsal articulation reaching beyond snout tip when hindlimb is adpressed along body; lateral metatarsals separated by webbing; inner metatarsal tubercle distinct, outer metatarsal tubercle very faint but present; webbing formula of foot according to Blommers-Schlösser (1979) 1(1), 2i(1.5), 2e(1), 3i(2), 3e(1), 4i(2.5), 4e(2), 5(0.5); relative toe length 1 <2 <5 & lt; 3 <4; toe discs distinctly enlarged. Skin dorsally granular; ridges bordering mid-dorsal band elevated, starting approximately 1 mm behind eyes (starting off bifurcated and converging toward the mid-line) and gradually becoming less distinct posteriorly; additional, interrupted and less distinct ridges are present posterior to the suprascapular region; two dark inter-ocular ridges are present either side of a fine cream-coloured vertebral band; supraocular tubercles are weakly enlarged, and do not form strong spines above the eyes; a modest dermal tarsal spine is present. Ventral skin smooth on throat and limbs, granular in posterior portion of abdomen. Femoral glands well delimited externally, consisting of 36 small granules on the left side and 44 small granules on the right side.

Dorsal colouration after one and a half years in preservative sepia, becoming increasingly grey posteriorly, mottled with almost black and brownish markings; dorsal folds are blackened over the suprascapular region but are otherwise brown; the tympanum is darker brown than the surrounding area; the lateral head has a cream stripe before the eye, immediately followed by a black stripe roughly 1 mm wide, and then mottled dark and light until the tympanum; bottom lip has alternating brown and cream annulations; dorsal forelimbs mottled blackish and Mikado brown reticulated with cream; dorsal hindlimbs brown with burnt umber crossbands on the thigh (three), shank (four), and foot (four); the cloacal region has a trapezoid of burnt umber around it; flank colouration fades from the sepia dorsal colouration through grey to the cream of the venter; ventrally the chin is medium fawn with a cream mid-ventral stripe and blackish vocal sacs, becoming blotched fawn among cream posteriorly to fully cream on the abdomen; the ventral legs are cream with brown and black areas toward the knees and on the anteroventral edge of the shank, including the femoral glands, which are distinct only in their texture and shape, and not in colour; the ventral foot is dark brown.

Colouration in life was as in preservative but more vibrant; see Figure 5.

Variation.

For a summary of measurement variation, see Table 1. All morphologically examined paratypes strongly resemble the holotype in morphology. Ridges between the eyes vary somewhat in shape, and in some specimens are black but in others do not have a distinct colouration from the surrounding head surface. The dorsal ridges vary from strongly to weakly pronounced, but are always present. There is no sexual dimorphism in inner metacarpal tubercle size. Snout shape in lateral view varies from rounded to square. The superciliary spines of all specimens are fairly low and indistinct. The femoral glands are remarkably variable, ranging from 26 granules in the right gland of ZSM 69/2016 to 69 granules in the left gland of MSZC 0032 (Fig. 6). Variation in colouration is as variable as is typical for members of this subgenus. A thin vertebral line can be present. The arms are always reticulated with whitish to light brown colouration. The head of ZSM 69/2016 (Fig. 6f) has a diamond-shaped lighter colouration covering its dorsal surface. The ventral colouration of this specimen is remarkably similar to that of all males, except that the blackish vocal sacs are absent. A juvenile, MSZC 0032, also had this diamond-shaped brown marking on its head (Fig. 6b).

Etymology.

Angano is a Malagasy word meaning ‘fable’. The new material for this species was collected on Expedition Angano , a research expedition to the Bealanana District of northern Madagascar to assess the impacts of forest fragmentation on the reptiles and amphibians. The epithet is used as an invariable noun in apposition to the genus name.

Call.

See the description provided above.

Natural history and distribution.

One specimen of this species has been collected in Antsahan’i Ledy, and numerous specimens of this species were encountered during fieldwork on the Ampotsidy mountains (Fig. 7). Calling males were generally found in association with slow flowing water, in the case of the holotype at the source of a spring, in close syntopy with Boophis madagascariensis and a Mantidactylus (Brygoomantis) species. Males called up to 1 m above the ground from fern fronds and other low foliage. Females were found both near to and away from water, during the day and at night, but were less commonly encountered. No eggs were observed, but highly ovigerous females were found in January (e.g. Fig. 6e). The call of the species is loud and carries over long distances, so that it can be heard alongside the calls of Boophis madagascariensis from well outside of some small forest fragments in the vicinity of Ampotsidy . In a small forest fragment where vouchers of Gephyromantis (Asperomantis) tahotra were collected (14.41689°S, 048.71435°E, 1368 m a.s.l.), G. angano sp. n. could also be heard; this appears to be the first ever record of any two Asperomantis species occurring in close syntopy ( Vences et al. 2017).