Gephyromantis horridus (Boettger, 1880)

Vences, Miguel, Koehler, Joern, Crottini, Angelica, Hofreiter, Michael, Hutter, Carl R., du Preez, Louis, Preick, Michaela, Rakotoarison, Andolalao, Rancilhac, Lois, Raselimanana, Achille P., Rosa, Goncalo M., Scherz, Mark D. & Glaw, Frank, 2022, An integrative taxonomic revision and redefinition of Gephyromantis (Laurentomantis) malagasius based on archival DNA analysis reveals four new mantellid frog species from Madagascar, Vertebrate Zoology 72, pp. 271-309 : 271

Gephyromantis horridus (Boettger, 1880)

Hemimantis horrida Boettger, 1880: 282

Note.

This species was described based on a juvenile specimen from Nosy Be, and a second specimen (an adult female) from the type locality has previously been reported by Glaw and Vences (2011). Pictures of both specimens are shown in Fig. 4 ; measurements are given in Vences et al. (2002) and Glaw and Vences (2011), respectively. The Tsaratanana population included in this species by Vences et al. (2002) is assigned to G. ranjomavo based on genetic data, and the only locality beside Nosy Be currently accepted for G. horridus is therefore Montagne d’Ambre. Measurements of the first male known from the Montagne d’Ambre population are given in Table 1 and photos in life of various individuals from this locality are included in Fig. 5 . The male is characterized by very prominent femoral glands of the same color as the surrounding skin of the ventral thigh, composed of approximately six large gland granules as recognizable in external view (Fig. 5 ). The male has no tibial gland. According to the measurements reported in Vences et al. (2002), Glaw and Vences (2011) and this study, SVL is 33.0-35.4 mm in two females and 33.5 in a male from Montagne d’Ambre, and 33.7 mm in a female from Nosy Be. The advertisement call of this species was previously unknown, and is described in the following for the Montagne d’Ambre population.

Call.

The advertisement call of specimen ZSM 126/2018 was recorded at 20:20-21:00 on 11 December 2017 on a muddy bank beside a very slow segment of a stream on the west slope of Montagne d’Ambre (12.5915°S, 049.1372°E, 939 m a.s.l.; air temperature not available). It consists of a series of short, pulsed notes (Fig. 6 ). They were extremely difficult to localize in the field due to their low amplitude. There is amplidude modulation within each call, with call energy being greatest at approximately 70% of the call’s duration, with initial notes being the least energetic ones. Within calls, notes are repeated at very constant intervals. Each note contains few clearly countable pulses repeated at an approximate rate of 500 pulses/second. Within regular call series, calls are emitted in rapid succession. Numerical parameters of 9 analyzed calls are as follows (range followed by mean ± standard deviation in parentheses): call duration 543-618 ms (585.1 ± 27.4 ms); note duration 6-12 ms (9.4 ± 1.7 ms); number of notes per call 17-19 (18.1 ± 0.8); note repetition rate within calls 29.4-31.0 notes/second (29.9 ± 0.7 notes/second); pulses per note 2-4 (3.0 ± 0.5); dominant frequency 1172-1369 Hz (1264 ± 71 Hz); prevalent bandwidth 900-3500 Hz. Calls were emitted in regular call series at a rate of approximately 41 calls/minute.

Figures

Figure 4. Preserved specimens of Gephyromantis horridus from the type locality Nosy Be. A, B Holotype SMF 7177 (juvenile) in dorsal and ventral views. C, D Specimen NMW 3643 (female) in dorsal and ventral views.

Figure 5. Specimens assigned to Gephyromantis horridus from Montagne d'Ambre National Park in life. A, B Adult female photographed in March 1994 (ZFMK 57433) in dorsolateral and ventral views. C - E Adult male (ZSM 126 / 2018) in dorsolateral, dorsal and ventral views. F, G Adult female discovered under rotten wood in May 2014 (not collected) in dorsolateral and dorsal views. Note the absence of tibial glands in all specimens. Not to scale.

Figure 6. Audiospectrogram and corresponding oscillogram of one advertisement call of Gephyromantis horridus (ZSM 126 / 2018) recorded on 11 December 2017 in Montagne d'Ambre National Park.