Gephyromantis malagasius (Methuen and Hewitt, 1913)

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 malagasius (Methuen and Hewitt, 1913)

Microphryne malagasia Methuen and Hewitt, 1913b: 55

Trachymantis malagasia ventrimaculatus Angel, 1935: 205; syn. nov.

Note.

As discussed above, we redefine G. malagasius based on molecular data from the holotype as containing those frogs previously considered as G. ventrimaculatus (e.g., Blommers-Schlösser and Blanc 1991; Vences et al. 2002; Glaw and Vences 2007). These frogs are easily recognizable by their reddish-brown dorsum with highly expressed tubercular skin texture, and a highly contrasted ventral color with grayish to bluish reticulations on a deep black ground color (Fig. 13 ). A tibial gland is absent. As hypothesized in the Molecular Phylogenetics section, we assume this typical color pattern has faded in the holotype of Microphryne malagasia while its general morphology roughly agrees with the morphology of the other specimens assigned to the species, despite being of smaller size (Fig. 14 ). Vences et al. (2002) discussed the mention in the original description ( Methuen and Hewitt 1913b) of "large white blotches" present on the "hidden surface of the thighs and tibiae", and interpreted this pattern as indicative of the reddish areas in life present on those frogs they assigned to G. malagasius . However, the described pattern might as well correspond to the contrasted markings found on the ventral side of the specimens previously considered as G. ventrimaculatus , which might have persisted in the hidden (not light-exposed) parts of the limbs at the time of the original description.

Vences et al. (2002) also provided information on the femoral gland of the G. malagasius holotype, which according to them consists of 1-2 granules (examined in external view), while the femoral glands of specimens assigned to G. ventrimaculatus were found to consist of nine granules. For this study, we unfortunately were not able to examine the gland of the Gephyromantis malagasius holotype in internal view, but a detailed look in external view (Fig. 13 ) reveals a rounded, well-defined structure, which may consist of several granules (more than the 1-2 previously reported), and clearly differs from the corresponding gland structures typical for specimens of lineage B where one or two single granules are arranged longitudinally on the ventral thigh; however, at least lineages C and D also have glands composed of more (4-7) granules, suggesting that femoral gland characteristics cannot be used to unambiguously allocate the Gephyromantis malagasius holotype to a genetic lineage. Summarizing morphometric measurements of Vences et al. (2002) and the present study, males measure 23.0-27.0 mm, females measure 29.1-29.8 mm, and the Gephyromantis malagasius holotype measures 20.2 mm SVL. We here provide bioacoustic data from Ranomafana National Park (Vohiparara) and from a second locality, Manombo.

Call.

The advertisement call of G. malagasius recorded at Vohiparara ( Vences et al. 2006, CD2, track 30) from ZFMK 62281 consists of a series of very short pulsed notes and is emitted in series at regular intervals (Fig. 15 ). There is amplidude modulation within each call, with call energy increasing from the beginning of the call reaching the maximum amplitude at about 40% of its duration and from there decreasing towards its end. Pulses within notes are partly fused, but clearly countable. Within calls, notes are repeated at regular intervals. Numerical parameters of 7 analyzed calls are as follows (range followed by mean ± standard deviation in parentheses): call duration 360-465 ms (428.4 ± 37.2 ms); note duration 8-17 ms (12.6 ± 2.9 ms); number of notes per call 8-10 (9.6 ± 0.8); note repetition rate within calls 19.8-21.1 notes/second (20.5 ± 0.5 notes/second); pulses per note 2-10 (6.2 ± 2.1); call repetition rate within call series approximately 17-18 calls/minute; dominant frequency 2606-3516 Hz (3127 ± 254 Hz); prevalent bandwidth 1800-6000 Hz.

A second recording from 23 February 2007 (Manombo; air temperature estimated at 23-25°C) consists of a series of pulsed notes and is emitted in series at regular intervals (Fig. 16 ). There is amplidude modulation within each call, with call energy increasing from the beginning of the call reaching the maximum amplitude at about 60% of its duration and from there decreasing towards its end. Pulses within notes are partly fused, but in most notes distinct pulses are recognizable and countable. Within calls, notes are repeated at regular intervals at a high rate. Numerical parameters of 14 analyzed calls are as follows (range followed by mean ± standard deviation in parentheses): call duration 348-446 ms (386.3 ± 34.5 ms); note duration 9-16 ms (12.2 ± 1.9 ms); number of notes per call 16-20 (17.5 ± 1.6); note repetition rate within calls 42.7-45.5 notes/second (44.7 ± 1.1 notes/second); pulses per note 2-9 (5.5 ± 1.9); call repetition rate within call series approximately 39-44 calls/minute; dominant frequency 2916-3192 Hz (3041 ± 107 Hz); prevalent bandwidth 1700-5500 Hz.

Distribution.

G. malagasius as redefined here is known based on genetically confirmed records from (1) the type locality Folohy, (2) Ranomafana, (3) Manombo, and (4) Befotaka-Midongy. Furthermore, morphologically identified specimens with the typical ventral pattern are known from (5) Andasibe, (6) Ambohitantely (based on phenotypically identified specimens collected by one of us [APR]; see Fig. 13G,H ), and (7) the type locality of the junior synonym Gephyromantis ventrimaculatus ("Isaka Ivondro, alt. 700 m"), which is located within or very close to the current Andohahela National Park. It is important to mention that the exact location of the type locality Folohy is uncertain. At this site, collections were made by "M. Herschell-Chauvin" in 1911 ( Methuen and Hewitt 1913b). Methuen and Hewitt (1913a) name the collector "Monsieur Herschell-Chauvin", probably referring to the English naturalist and photographer Charles Herschell-Chauvin who worked in Tamatave (=Toamasina) in the first years of the 20th century. Methuen and Hewitt (1913a) place the locality Folohy "in the neighbourhood of Tamatave", and also Blommers-Schlösser and Blanc (1991) plot Folohy as near-coastal locality close to Toamasina in their distribution maps. Barbour and Loveridge (1929) locate Folohy "east of Lake Alaotra" for a frog specimen exchanged from the Transvaal Museum. The catalogue of the Museum of Comparative Zoology, Harvard, includes a lemur specimen (MCZ 18740) collected by Frederick Roelker Wulsin in 1915, with the verbatim locality information "Folohy forest, 100 miles west of Tamatave" (https://www.idigbio.org/portal accessed 19 November 2021), which however is unlikely to be correct as it would place the site onto Madagascar’s high plateau, outside the main rainforest area. Along with Blommers-Schlösser and Blanc (1991) we here assume that Folohy refers to a low- or mid-elevation site close to Toamasina.

The occurrence of individuals morphologically corresponding to G. malagasius as redefined herein in Andasibe is supported by three records: one voucher specimen collected by Denis Vallan and reported in Vences et al. (2002); one specimen photographed by Daniel S. Moen; and one specimen photographed by Devin Edmonds in the Mitsinjo forest on 4 December 2014 (https://www.inaturalist.org/observations/2315204).

Figures

Figure 13. Specimens of Gephyromantis malagasius (previously considered as G. ventrimaculatus, herein considered to be a junior synonym of G. malagasius), in life. A, B Adult male from Ranomafana in dorsolateral and ventral view, photographed 2006, probably corresponding to voucher specimen ZSM 537 / 2006 (ZCMV 3362). C, D Adult male from Manombo, ZSM 2464 / 2007 (ZCMV 5497) in dorsolateral and ventral view, photographed 2007. E, F Adult male from Ranomafana (Vohiparara), photographed 1996, possibly corresponding to voucher specimen ZFMK 62281. G, H Adult male from Ambohitantely, not clearly assignable to a voucher specimen, photographed in 2017 in Ambohitantely Special Reserve. Not to scale.

Figure 14. A, B Preserved holotype of Gephyromantis malagasius (originally named Microphryne malagasia; specimen TMP 10076) in dorsal and ventral view. C, D Preserved lectotype of Trachymantis malagasia ventrimaculatus (MNHN 1935.172), herein considered as a junior synonym of G. malagasius. Photos C and D by Antoine Fraysse, project MNHN-RECOLNAT (ANR- 11 - INBS- 0004), photographed in 2015 (http: // coldb. mnhn. fr / catalognumber / mnhn / ra / 1935.173)

Figure 15. Audiospectrogram and corresponding oscillogram of one advertisement call of Gephyromantis malagasius recorded at Vohiparara. The oscillogram below shows a 100 ms section of the call figured above, showing two notes and their repective pulse structure. Recording band-pass filtered at 1500 - 7500 Hz.

Figure 16. Audiospectrogram and corresponding oscillogram of one advertisement call of Gephyromantis malagasius recorded at Manombo. The oscillogram below shows a 100 ms section of the call figured above, showing four notes and their repective pulse structure. Recording band-pass filtered at 1500 - 6200 Hz.