Guibemantis albomaculatus, Lehtinen & Glaw & Vences & Rakotoarison & Scherz, 2018

Lehtinen, Richard M., Glaw, Frank, Vences, Miguel, Rakotoarison, Andolalao & Scherz, Mark D., 2018, Two new Pandanus frogs (Guibemantis: Mantellidae: Anura) from northern Madagascar, European Journal of Taxonomy 451, pp. 1-20 : 6-13

Guibemantis albomaculatus sp. nov.

urn:lsid:zoobank.org:act:D33E461D-331B-4FE4-8808-DB476F9FB2AA

Figs 1–4

Suggested common name: White-spotted Malagasy Pandanus Frog.

Diagnosis

Assigned to the subgenus Pandanusicola of the genus Guibemantis based on its small body size, phytotelm-breeding habitats (in Pandanus plants), moderate webbing between toes, connected lateral metatarsalia, the presence of both inner and outer metatarsal tubercles, type 2 femoral glands in males, and DNA sequence similarities ( Glaw & Vences 2006). The new species is characterized by the unique combination of the following characters: (1) male SVL 18.9–22.9 mm, female SVL 20.9–26.7 mm, (2) two conspicuous parallel light-colored dorsolateral lines on the dorsum, (3) small white spots on the darkly colored arms, legs and flanks, (4) dark ventral surfaces to hands and feet, (5) distinct rostral stripe and (6) orange femoral glands.

Etymology

The specific epithet is used as a descriptive adjective and refers to the small white spots present on the arms, legs and flanks.

Material examined

Holotype

MADAGASCAR: adult ³, Montagne d’Ambre National Park , northern Madagascar [geographical coordinates not taken, but most likely from a Pandanus plant very close to the Gîte d’étape (12.5270° S, 49.1720° E, 1055 m a.s.l.) or less likely from the Voie des mille arbres (ca 12.5200° S, 49.1756° E, 1052 m a.s.l.)], 18 Feb. 2003, F. Glaw, R.D. Randrianiaina and A. Razafimanantsoa leg. [ ZSM 0895 /2003 ( FGMV 2002.905 )] ( Fig. 3 ).

Paratypes (n = 19)

MADAGASCAR: 5 specs, Manongarivo Special Reserve, 20 Feb. 1992, C.J. Raxworthy, A. Raselimanana and J.B. Ramanamanjato leg. ( UMMZ 212592–212596); 1 spec., Montagne d’Ambre National Park, Antomboka River, 1150 m a.s.l., 15 Nov. 1991, C.J. Raxworthy, A. Raselimanana and J.B. Ramanamanjato leg. ( UMMZ 212585); 3 specs Montagne d’Ambre National Park, Antomboka River, 950 m a.s.l., 21 Nov. 1991, C.J. Raxworthy, A. Raselimanana and J.B. Ramanamanjato leg. ( UMMZ 212587, UMMZ 212588, UMMZ 212591); 2 specs Manongarivo Special Reserve, “Camp 0”, 13.9756° S, 48.4267° E, 688 m a.s.l., 1–2 Feb. 2003, F. Glaw, R.D. Randrianiaina and M. Vences leg. [ ZSM 0816/2003 ( FGMV 2002.735), ZMA 19582 ( FGMV 2002.733)]; 1 spec., same collecting data as for preceding ( UADBA uncatalogued, FGMV 2002.736); 1 spec., Montagne d’Ambre National Park, 12.5275° S, 49.1725° E, 1010 m a.s.l., 19 Mar. 2000, F. Glaw, K. Schmidt and M. Vences leg. [ ZSM 496/2000 ( FGMV 2000.356)]; 4 specs, Montagne d’Ambre National Park, same collection data as for holotype [ ZSM 0893/2003 ( FGMV 2002.0901), ZSM 0894/2003 ( FGMV 2002.0904), UADBA uncatalogued ( FGMV 2002.902), and ZMA 19660 ( FGMV 2002.997)]; 1 ♀ [ UADBA uncatalogued ( FGZC 1010)] and 1 juv. [ UADBA uncatalogued ( FGZC 1012)], Montagne d’Ambre National Park, Voie des mille arbres, 12.5167° S, 49.1767° E, 1050 m a.s.l., 23 Feb. 2007, F. Glaw, P. Bora, H. Enting, J. Köhler and A. Knoll legs.

The six paratypes from UADBA and ZMA were not available for morphometric comparison, but were sequenced and attributed genetically to G. albomaculatus sp. nov. (see Fig. 1 ).

Description of the holotype

Adult male. Head longer than wide and slightly wider than body; snout rounded in dorsal, ventral and lateral views; canthus rostralis rounded; nostrils much nearer to tip of snout than to eye, internarial distance 83% of interorbital distance; tympanum distinct 42% of horizontal eye diameter; dark supratympanic fold present from posterior edge of eye around the tympanum nearly to the arm insertion; one small round patch of vomerine teeth medial between eye and choanae on either side of head; tongue damaged, shape of tip unknown. Arms thin, lower arm is 91% of hand length; relative finger length 1<2<4<3, finger discs moderately enlarged and squared off at tips in a rounded ‘T’ shape, only traces of webbing between fingers, subarticular tubercles prominent. Hindlimbs relatively thin, femur length 85% of tibia length, foot length 83% of tibia length; lateral metatarsalia connected; inner metatarsal tubercle oblong in shape (0.6 mm in length, 0.3 mm in width); outer metatarsal tubercle round (0.4 in diameter); webbing formula between toes 1(1) 2i(1) 2e(1) 3i(2) 3e(1.5) 4i(3) 4e(3) 5(1.5); relative length of toes 1<2<5<3<4; toe discs moderately enlarged, width of fourth toe disc 58% of width of third finger disc. Femoral glands distinct, oblong in shape (4.4 mm long, 1.7 mm wide) with approximately 35 granules contained inside. Cloaca not clearly recognizable; skin is finely granular dorsally, more roughly granular ventrally. There is also a patch of whitish granules on the belly. For morphometric measurements see Table 1 .

After seven years in preservative, the dorsal background coloration is medium brown which contrasts with the darker brown flanks. Two prominent light dorsolateral lines separate the medium brown color of the dorsum from the dark brown of the flanks. A single, relatively thick rostral stripe is present. Dorsal color of arms, legs, hands and feet is medium brown with abundant small white spots throughout. Vague light annuli are found on some digits just proximal to the finger and toe discs but are not prominent. Toe and finger discs have a similar dark coloration as the dorsal surface of the hands and feet, except for the discs of fingers I and II, which have a much lighter coloration. Venter is cream with abundant brown spots along jawline, chin and especially on the ventral surface of the hindlimbs. The pupil appears black and the iris is white.

Coloration in life

The life coloration of the holotype is unknown. However, based on photographs of live individuals from Manongarivo and Montagne d’Ambre ( Fig. 4 ), there appear to be a number of coloration differences compared to preserved material. In life, the iris color is gold or bronze (white or gray in preservative). Portions of the arms and fingers as well as lateral areas of the head have a yellow or yellow-green color in life (beige in preservative). The more lightly colored toe and finger discs are a dull yellow (beige or whitish in preservative). The ventral skin is largely translucent such that chest and belly musculature and bones in the limbs are easily visible (not apparent in preservative). In males, femoral glands (type 2, as defined by Glaw et al. 2000) appear orange in life. Sexually mature males also possess a distinct white coloration on the lateral portions of the throat. A color photograph of a specimen of this species from Manongarivo is shown in Glaw & Vences (2007: 203, fig. 4).

Variation

The new species is similarly sized to most other Pandanusicola (overall mean SVL 22.8 ± 2.1 mm, n = 15). Females appear to be larger on average than males (female mean SVL 24.0 ± 1.7 mm, n = 9; male mean SVL 21.3 ± 1.5 mm, n = 6). While all individuals seem to possess a dark rostral stripe, some individuals have an additional gold colored one medial to the first. The small white spots on the dorsal surface of the arms, legs and flanks also vary in coverage and density among individuals. Some individuals only possess them in abundance on the hindlimbs and sparingly elsewhere. Other individuals have an abundance of these spots not only on both limbs and the flanks, but also on the back and head as well. While yellowish dorsal coloration is present in all known individuals, the dorsal base color intermixed with it differs among individuals. Most individuals have a dorsal base color of medium to dark brown but one individual was notably lighter than other specimens examined ( Fig. 4B ). The prominence and length of the two parallel dorsal lines also varies among individuals, with those from Manongarivo typically being more distinct. Some individuals possess a small but distinct light-colored spot between the eyes, other individuals lack this feature. Many individuals possess no obvious markings on the dorsum but a few have several vague dark splotches. On the ventral surface, most individuals possess fine brown spots on the jawline and on the undersurface on the limbs. Other individuals have these spots on the throat and chest as well. No variation was observed in the webbing on the hand. However, webbing on the foot was variable for some digits (range, where variable, given in parentheses): 1(1) 2i(1) 2e(1) 3i(2) 3e(1–2) 4i(3) 4e(2.75–3) 5(1–2). The distinct light-colored annuli present before the terminal phalange of each digit, that are prominent in some Pandanusicola , are usually only weakly developed but can be conspicuous in some individuals.

Differential diagnosis

Among Pandanusicola , the new species is distinguished from G. annulatus Lehtinen, Glaw & Vences, 2011 , G. bicalcaratus (Boettger, 1913) , G. flavobrunneus , G. liber , G. pulcher , G. punctatus and G. tasifotsy by the presence of two conspicuous parallel light-colored dorsolateral lines, by the presence of small white spots on more darkly colored arms, legs and flanks and by large genetic differences. By comparison, G. pulcher is a characteristic bright green in color with large irregular dark dorsal spots; G. bicalcaratus is yellowish or brownish dorsally with usually relatively few irregularly shaped dark spots; G. flavobrunneus is much larger (up to 38 mm SVL; Glaw & Vences 2007) and is primarily yellow with extensive brown dorsal markings; G. liber is rather variable in coloration but tends to be brownish overall, the entire surface of the throat of males is bright white, and this species does not breed in Pandanus plants; G. tasifotsy does not breed in Pandanus either and has a copper metallic coloration on the nares and/or eye orbits and prominent white lateral blotches; G. annulatus and G. punctatus are cream or olive-colored (respectively) and have abundant small dark spots; G. methueni (Angel, 1929) and G. wattersoni can have parallel dorsolateral light colored lines on the dorsum but most individuals lack this feature and it is usually poorly developed in those individuals that possess it. Furthermore, G. wattersoni is primarily a yellow or light brownish frog dorsally and the flanks and legs in G. wattersoni are always lightly colored whereas they are typically very dark in the new species. In G. methueni , the ventral surfaces of the hands and feet are very lightly colored, whereas they are dark in the new species. Guibemantis albolineatus (Blommers-Schlösser & Blanc, 1991) lacks both vomerine teeth and a rostral stripe (both present in the new species), has a distinctly shaped snout that is square in dorsal and ventral view and is notably smaller in overall body size (see Table 1 ). The recently described G. milingilingy differs by lacking white spots (present in the new species), by having banded forelimbs (unbanded in the new species), by having yellow femoral glands in males (orange in the new species) and by having a mid-dorsal stripe (absent or poorly developed in the new species). No other described species of Pandanusicola has the combination of light colored parallel dorsal lines with small white spots on the dark unbanded arms, legs and flanks.

Distribution

At present G. albomaculatus sp. nov. is known from rainforest habitats in two areas: the Manongarivo Special Reserve (type locality) and Montagne d’Ambre National Park, both in northern Madagascar ( Fig. 2 ). The elevational range so far documented is from 950–1150 m.

Based on the limited knowledge of the distribution, we suggest a conservation status of "Data Deficient".

Natural history

Little is known of the natural history of this species. Specimens have only been collected from Pandanus plants and are probably obligate Pandanus breeders, like most other species in this group. Vocalizations have not been recorded and eggs and larvae have yet to be documented.

Available names and comparisons

The only available synonyms that could possibly be applied to this species are Gephyromantis albogularis Guibé, 1947 and Gephyromantis variabilis Millot & Guibé, 1951 , both of which were confidently assigned to Guibemantis liber by Lehtinen et al. (2011).

Males of Guibemantis liber have a throat that is bright white over its entire surface. The whitish coloration on the throat of males in G. albomaculatus sp. nov. does not cover the entire surface nor is it as brightly white as in G. liber .

Remark

This species has been previously listed as Guibemantis sp. aff. albolineatus “Manongarivo” in Glaw & Vences (2007: 202–203), Guibemantis bicalcaratus (Manongarivo) in Lehtinen et al. (2007) and Guibemantis sp. Ca 12 in Vieites et al. (2009) and Perl et al. (2014).

Figures

Fig. 1. Maximum Likelihood tree of species in the genus Guibemantis Dubois, 1992, subgenus Pandanusicola Glaw & Vences, 1994 (rooted with the nominal subgenus). The tree is based on an analysis of 535 bp of the mitochondrial 16S rRNA gene and contains representatives of all valid species of Guibemantis. Numbers at nodes are bootstrap proportions from a Maximum Likelihood bootstrap analysis (500 replicates) in percent (BP), and posterior probabilities (PP) from Bayesian Inference (only shown for nodes with either BP> 60% or PP> 0.95). Inset photos show the two new species described herein.

Fig. 2. Map of northern Madagascar, showing mostly verified distribution records of the two species of Guibemantis Dubois, 1992 described herein, and of the recently described G. milingilingy Bletz, Scherz, Rakotoarison, Lehtinen, Glaw & Vences, 2018. The locality Ambatovaky is only based on similarities in coloration and is in need of confirmation. The map shows the remaining primary vegetation of Madagascar (www.vegmad.org), green colors indicating rainforest, brown/orange colors deciduous dry forest.

Fig. 3. Preserved holotype specimens of the two new species described herein, Guibemantis woosteri sp. nov. [ZSM 5063/2005 (ZCMV 2044)] and G. albomaculatus sp. nov. [ZSM 0895/2003 (FGMV 2002.905)], in dorsal and ventral view. Scale bars = 5 mm.

Fig. 4. Guibemantis albomaculatus sp. nov. in life. A–B. Two specimens with unknown sex or voucher numbers from Montagne d’Ambre. C–D. ♀, from Montagne d’Ambre, probably ZSM 894/2003 (FG/ MV 2002.904). e. Specimen from Manongarivo with unknown sex or voucher number. F–G. ³, from Manongarivo, ZSM 816/2003 (FG/MV 2002.735).