Gephyromantis (Vatomantis) lomorina, Scherz, Mark D., Hawlitschek, Oliver, Razafindraibe, Jary H., Megson, Steven, Ratsoavina, Fanomezana Mihaja, Rakotoarison, Andolalao, Bletz, Molly C., Glaw, Frank & Vences, Miguel, 2018
Scherz, Mark D., Hawlitschek, Oliver, Razafindraibe, Jary H., Megson, Steven, Ratsoavina, Fanomezana Mihaja, Rakotoarison, Andolalao, Bletz, Molly C., Glaw, Frank & Vences, Miguel, 2018, A distinctive new frog species (Anura, Mantellidae) supports the biogeographic linkage of two montane rainforest massifs in northern Madagascar, Zoosystematics and Evolution 94 (2), pp. 247-261 : 248-255
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|Gephyromantis (Vatomantis) lomorina|
Gephyromantis (Vatomantis) lomorina sp. n. Figs 1, 2, 3, 4, Table 1, Suppl. materials 1, 2
ZSM 419/2016 (ZCMV 15221), adult male, collected at 21h20 on 18 November 2016 near Camp Simpona (ca. 14.4366°S, ca. 49.7434°E, ca. 1325 m a.s.l.) in Marojejy National Park, Sava Region, northeastern Madagascar, by M. D. Scherz, J. H. Razafindraibe, M. C. Bletz, A. Rakotoarison, A. Razafimanantsoa, and M. Vences (Fig. 2).
ZSM 418/2016 (ZCMV 15220), female, and ZSM 420-421/2016 (ZCMV 15222 and 15271), two males, collected between 17 and 19 November 2016 from the same locality and by the same collectors as the holotype; UADBA 60294-60299 (ZCMV 15219, 15223, 15247, 15270, 15272, and 15273), one male, three females, a subadult and an unsexed adult, collected between 17 and 19 November 2016 from the same locality and by the same collectors as the holotype; ZSM 1549/2012 (FGZC 3714), adult male, collected on 30 November 2012 in a creek near the campsite on the Sorata massif (13.6829°S, 49.4403°E, 1325 m a.s.l.), Sava Region, northeastern Madagascar, by O. Hawlitschek, F. Glaw, A. Rakotoarison, F. M. Ratsoavina, T. Rajoafiarison, and A. Razafimanantsoa; ZSM 1545-1547/2012 (FGZC 3716, 3734, and 3664), adult males, and ZSM 1548/2012 (FGZC 3721), adult female, collected between 28 and 30 November 2012 from a creek below a bamboo forest on the Sorata massif (13.6772°S, 49.4413°E, 1394 m above sea level), Sava Region, northeastern Madagascar, by O. Hawlitschek, F. Glaw, A. Rakotoarison, F. M. Ratsoavina, T. Rajoafiarison, and A. Razafimanantsoa; ZSM 318/2016 (SM AEA 063), adult female, and UADBA uncatalogued (SM AEA 062), unsexed adult, collected between 18h45 and 18h50 on 30 May 2016 in Andravory (13.7385- 13.7388°S, 49.5310°E, 1164-1179 m a.s.l.), Sava Region, Antsiranana Province, northeastern Madagascar, by S. Megson, R. Walker, W.-Y. Crawley, and T. H. Rafeliarisoa (Figs 3-4).
A species assigned to the genus Gephyromantis on the basis of its granular skin, moderately enlarged finger tips, small femoral glands consisting of a small number of large granules and present in males only (thus of type 2 as defined by Glaw et al. 2000), and bifid tongue. Within the genus Gephyromantis , assigned to the subgenus Vatomantis on the basis of its small size, connected lateral metatarsalia, absence of an outer metatarsal tubercle, paired subgular vocal sacs of partly whitish colour, greenish skin colouration, and riparian ecology. Gephyromantis lomorina sp. n. is characterized by the possession of the following suite of morphological characters: (1) granular skin, (2) reddish eyes, (3) mottled green and black skin, (4) males with paired subgular vocal sacs of partly white colour, (5) males with bulbous type 2 femoral glands consisting of a small number (2-3) of large granules, (6) white spots on the venter, (7) SVL 20.2-25.5 mm, and (8) fourth finger much longer than second. Furthermore, the species is characterised by distinctive, 1681-1827 ms advertisement calls of relatively low intensity, consisting of 24-30 individual pulsed notes, with 2-4 pulses per note, an inter-note interval of 41-75 ms, and a dominant frequency of 5124-5555 Hz. DNA sequence data from the 16S gene fragment supports the high divergence of this taxon to all other Gephyromantis , and is in agreement with its subgeneric assignment, albeit without statistical support (Fig. 1).
Within the genus Gephyromantis , G. lomorina sp. n. can be distinguished from all subgenera except Laurentomantis and Vatomantis on the basis of the combination of femoral glands composed of few large granules (vs. composed of many, small granules; note that G. klemmeri is here treated separately from all other subgenera, below, due to its unclear assignment), SVL <26 mm (vs.> 27 mm in all other subgenera except Gephyromantis ), absence of a white stripe along the upper lip (vs. general presence in subgenus Gephyromantis ), and absence of distinctly enlarged supraocular spines (vs. presence in Asperomantis and some Duboimantis ). It may be distinguished from all members of the subgenus Laurentomantis ( G. ventrimaculatus (Angel), G. malagasius (Methuen & Hewitt), G. striatus (Vences, Glaw, Andreone, Jesu & Schimmenti), G. horridus (Boettger), and G. ranjomavo Glaw & Vences) by paired subgular vocal sacs (vs. single), absence of outer metatarsal tubercles (vs. presence), and at least partly greenish dorsal skin (vs. mostly yellowish to brown to reddish), and from several of these by the absence of tibial glands in males (vs. typical presence). Within the subgenus Vatomantis , G. lomorina sp. n. may be distinguished from all species by its more granular dorsal skin (vs. granular but not rough) and venter spotted with white (vs. generally without whitish spotting except on the chin and over the sternum); from G. rivicola (Vences, Glaw & Andreone) and G. webbi (Grandison) by its reddish iris colouration (vs. copper and greenish, respectively); from G. silvanus (Vences, Glaw & Andreone) by its smaller size (SVL 20.5-25.5 mm vs. 31 mm) and partly whitish vocal sacs (vs. yellowish); from G. webbi by femoral glands composed of few large granules (vs. composed of many, small granules) and large inner metatarsal tubercle (vs. small). Gephyromantis lomorina sp. n. may be distinguished from G. klemmeri by its roughly granular dorsal skin (vs. smooth to shagreened), greenish skin colour (vs. brownish), reddish iris (vs. gold), and strongly protruding inner metatarsal tubercle (vs. small and not protruding).
The call of G. lomorina sp. n. may be distinguished from all Vatomantis and Laurentomantis species in having notes that are clearly pulsed (vs. unpulsed notes in all species except G. ventrimaculatus ); Gephyromantis ventrimaculatus has a higher number of pulses per note notes than G. lomorina sp. n. (ca. 6 pulses per note vs. 2-4 in G. lomorina sp. n.). The call of G. lomorina sp. n. is somewhat similar to that of G. klemmeri , especially in having pulsed notes, but the call duration is much longer (1681-1827 ms vs. 626-982 ms), the call has a more distinct amplitude decay (vs. complex amplitude modulation, see Vences et al. 1997), the notes of the call are more homogeneous (vs. distinct components of the call), and it lacks frequency modulation (vs. frequency modulated toward the end of the call).
Description of the holotype.
A specimen in a good state of preservation, a piece of tissue taken from the left thigh. SVL 23.3 mm; for other body measurements see Table 1. Body slender. Widest part of head marginally wider than widest part of body. Snout rounded in dorsal and lateral view, protruding slightly over upper jaw in lateral view. Nostrils not distinctly protruding, with lateral openings. Canthus rostralis distinct, concave. Loreal re gion concave, vertical. Tympanum distinct, fairly small, 53% of eye diameter. Supraocular spines absent. Weakly distinct supratympanic fold running from the eye over the tympanum to above the insertion of the arm. Forelimbs and hindlimbs slender. Inner and outer metacarpal tubercle present, both indistinct. Finger discs enlarged, round. Subarticular tubercles distinct, dark in colour. No webbing between fingers. Comparative finger lengths 1 <2 <4 <3, fourth finger much longer than second finger. Toe discs slightly enlarged, smaller than finger discs. Traces of webbing between toes. Comparative toe length 1 <2 <3 = 5 <4. Inner metatarsal tubercle rather large (length about 1.3 mm), protruding strongly distally to resemble a toe. Outer metatarsal tubercle absent. Lateral metatarsalia connected. Dorsal skin granular, with numerous small tubercles arranged in mostly parallel lines running posteriorly over the dorsum, with convergent lines of tubercles on the posterior head, and weak rows of tubercles on the hindlimbs and forelimbs. Femoral glands round, consisting of three large granules with an indentation in their middle (similar to type 2 sensu Glaw et al. 2000). Vomerine teeth absent. Maxillary teeth present. Choanae small and lateral. Subgular vocal sacs whitish in distensible portion, blackish on the jaw, fairly small. Tongue bifid, free posteriorly.
Colouration in life (Fig. 2) dorsally mottled with greens, browns, blacks, and yellows. Particularly green over the eyes. Raised ridges on the back were mostly yellowish, but some also with an orange hint. Flanks and lateral head as dorsum. Legs dark brown with yellow-green cross-bands, three on the thigh, three on the shank, and two on the tarsus. The tarsus and dorsal foot were a more ruddy brown than the rest of the body, mottled with a tan orange on the toes and on the heel. A few tubercles on the legs were red. A whitish annulus was present before the terminal disc of each toe and finger. The forelimbs were as the shanks and foot, ruddy brown mottled with yellow-green and dark brown, with a few red tubercles. Whitish spots were present in the inguinal region and the ventral portion of the flank, and also two cream stripes were present below the eye that continued on the bottom lip. The tympanum was distinctly brownish. The venter was umber in base colour with more reddish portions of translucent skin on the ventral side of the arms. The chin had white portions along the lip and especially on the vocal sacs, but the jaw itself was blackish. The venter had distinct white spots. The ventral hindlimbs were umber with irregular pale olive and yellow patches on the ventral thigh and shank. The ventral tarsus, foot, and hand were umber. The femoral glands were fleshy in colour, and the area ventral to the cloaca was pinkish. The iris was copper above and below, and rusty anteriorly and posteriorly, with blackish reticulations and a blackish line above and below the centre of the pupil.
After six months in preservative, the colouration of the holotype has faded to become more uniformly brownish, and areas that were greenish in life have become cream. White areas of the venter are still immaculately white.
All paratypes resemble the holotype in gross morphology; see Table 1 for morphological variation. Tympanum diameter ranges from 47-79 % of eye, without strong sexual dimorphism in tympanum size. Females are marginally but not significantly larger than males (t-test, t = -1.9215, df = 13, p = 0.07687). Several paratypes have smaller femoral glands than the holotype. Femoral glands are composed of 2 or 3 large granules (mean 2.875 ± 0.35, n = 8; all but one of eight examined specimens with 3 granules). Females have miniscule raised bumps in the femoral area. There is considerable variation in colouration of the specimens, with some individuals being much darker, and others being more green (Figs 3-4). The chin of females is more solidly dark than that of males, and they lack most white spots. A pair of cream stripes below the eye that continue on the lower lip is present in all specimens. Two specimens (UADBA 60299, and ZSM 1545/2012, Fig. 4) have a bright vertebral stripe.
Call recordings were made in Marojejy from the holotype ZSM 419/2016 at its collection locality at a distance of 0.5 m during light rain (Suppl. material 1, DOI: 10.7479/nmx8-aq7v). The call is interpreted as an advertisement call as it resembles the advertisement calls of the subgenus Laurentomantis , and was emitted without close proximity to other individuals, and while the frog was otherwise inactive ( Köhler et al. 2017). Air temperature was not recorded. A strict FFT bandwidth filter was applied to the dataset to remove all sound below 400 Hz in order to remove wind artefacts. Two calls were recorded from the holotype, but numerous calls were heard whilst searching for this species along the river where it was found. Calls consisted of a rapid series of 24-29 extremely short notes (note duration 6.3 ± 1.9 ms, range 2-10 ms, n = 53; Fig. 5a), each of which had 2.6 ± 0.6 pulses (2-4 pulses, n = 50), the peak amplitudes of which were separated by 2.7 ± 0.6 ms (1-4 ms, n = 53; Fig. 5b). Notes were separated by silent inter-note intervals of 64.6 ± 5.5 ms (47-75 ms, n = 51). The call was amplitude modulated, increasing in amplitude quickly and slowly decaying toward the end of the call. Call duration was 1769-1827 ms (n = 2), with one inter-call interval recorded of 2399 ms. Generally, however, the calls appeared to be emitted rather irregularly. Dominant frequency was 5124-5512 Hz, and the 90 % bandwidth was from 2723-2759 to 6391-6462 Hz.
Similar calls were recorded in Sorata from ZSM 1549/2012 at its collection locality (Suppl. material 2, DOI: 10.7479/nmx8-aq7v). Air temperature was not recorded. The calls strongly resembled those recorded from the holotype. Three calls were recorded, but one was cut off and another had loud calls of Gephyromantis (Duboimantis) sp. in the background, so only one was analysed. The call consisted of a rapid series of 31 extremely short notes (note duration 6.9 ± 0.8 ms, range 6-10 ms, n = 27 analysed), each of which had 2.0 ± 0.2 pulses (2-3 pulses, n = 27), the peak amplitudes of which were separated by 3.0 ± 0.4 ms (2-4 ms, n = 27). Notes were separated by silent inter-note intervals of 46.3 ± 3.8 ms (41-55 ms, n = 27). The call was amplitude modulated in the same way as that of ZSM 419/2016. Call duration was 1681 ms, and one inter-call interval was ca. 1900 ms. In general however calling was irregular. The dominant frequency was 5555 Hz, and the 90 % bandwidth was from 4979 to 6003 Hz. The call with a loud Gephyromantis (Duboimantis) sp. in the background was considerably shorter, and consisted of just 11 notes over a duration of 515 ms, but we suppose this call may have been disturbed as it lacked amplitude reduction toward its end.
The new species is known from three localities in northeastern Madagascar: (1) Marojejy National Park (type locality), (2) Sorata massif, and (3) Andravory massif (Fig. 6). All specimens were collected between 1164 and 1394 m a.s.l.
Specimens were collected near mountain streams in pristine montane riparian rainforest (Fig. 4g). In Marojejy National Park they were encountered during and after light rain, sitting in inconspicuous locations, especially on the fronds of tree ferns, but also on other low vegetation, between a few centimetres and up to 2 m above the ground. Specimens in Sorata were found in similar positions during dry weather, in the days just before the beginning of the rainy season. Males called irregularly and softly (see the call description above). Population density in Marojejy was remarkably high, with around three or four individuals being found along a 10 m stretch of stream. The observed density in Sorata was lower, possibly due to the absence of rain during the observation period. The species occurred in close sympatry with a number of other mantellids, but only few of these (especially Mantidactylus aff. femoralis ) were found in the same microhabitat. Several specimens from Marojejy had pinkish mites (probably of the genus Endotrombicula ; see Wohltmann et al. 2007) embedded within translucent whitish pustules on the skin of their fingers, toes, and bodies. Nothing is known about the reproduction of this species, but the calling sites suggest an association with lotic water.
The specific epithet is the Malagasy word lomorina , meaning 'covered in moss’, in reference to the green, mossy appearance of the species in life. It is used as an invariable noun in apposition to the genus name.
The species occurs in two regions with very different conservation situations: the highly protected forests of Marojejy National Park, and the unprotected, isolated, and highly threatened forests of Sorata and Andravory. Maminirina et al. (2008) report a study site in the rainforest of Sorata at 970 m a.s.l., but in our surveys in 2012, we detected larger patches of forest only at elevations of ca. 1270 m and above. The new species was collected at lower elevation in Andravory (1164-1179 m a.s.l.), where forest persists. Higher elevation levels of Sorata are covered by high-elevation forests different to those where G. lomorina sp. n. was found, and these therefore may not support this species. In this area, the species is therefore directly threatened by the loss of the only forests in which it has been detected.
By contrast in Marojejy, forest extends down to roughly 200 m a.s.l., is highly protected, and the high elevation forest where this species occurs does not seem to be facing any immediate threats. Although the tourist load to Marojejy is relatively high, and the area upslope from the collection locality of the holotype and several paratypes is somewhat polluted with refuse from the nearby tourist camp, the species was abundant around this stream during our survey there in 2016, and presumably inhabits other streams around the same elevation across the massif.
Accommodating this spread of risk is a challenge for the IUCN Red List status. However, G. (V.) lomorina sp. n. is not the first species to have almost exactly this distribution. Rhombophryne vaventy Scherz, Ruthensteiner, Vences & Glaw was recently recovered from Sorata ( Peloso et al. 2016, Scherz et al. 2016, Lambert et al. 2017) after initially having been described from the same type locality as G. lomorina sp. n. ( Scherz et al. 2014). In the case of this species, Scherz et al. (2017a) argued for a classification of Endangered under IUCN criterion B1ab(iii), i.e. an extent of occurrence under 5000 km2 (B1), known from fewer than five threat-defined locations (a), and an observed, estimated, inferred, or projected decline (b) in the area, extent, and/or quality of habitat (iii). Given the similar situation in G. lomorina sp. n., i.e., very similar, limited distribution and ongoing reduction and threat to a substantial part of its habitat (i.e., the forests of Sorata and Andravory), we propose that the same threat status and justification be given for this species.
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