Guibemantis (Pandanusicola) pulcherrimus, Vences & Hutter & Glaw & Rakotoarison & Raselimanana & Scherz, 2023

Vences, Miguel, Hutter, Carl R., Glaw, Frank, Rakotoarison, Andolalao, Raselimanana, Achille P. & Scherz, Mark D., 2023, A new species of Pandanus-dwelling frog from northern Madagascar related to Guibemantis pulcher, Zootaxa 5306 (1), pp. 97-115 : 108-112

Guibemantis (Pandanusicola) pulcherrimus sp. nov.

Figs. 7‒9

Holotype. ZSM 518/2009 (field number ZCMV 11217 ), adult female, collected by M. Vences, D.R. Vieites, F.M. Ratsoavina, R.D. Randrianiaina, E. Rajeriarison, T. Rajoafiarison and J.L. Patton on 23 June 2009 near a site locally named Hevirina , western slope of the Makira Massif, Analanjirofo Region, Madagascar (GPS coordinates not taken, but coordinates of Hevirina are 15.4490°S, 49.1119°E, 1093 m a.s.l.).

Paratypes. Eight specimens. ZSM 519/2009 (ZCMV 11249) and ZSM 520/2009 (ZCMV 11264), two adult females, collected by M. Vences, D.R. Vieites, F.M. Ratsoavina, R.D. Randrianiaina, E. Rajeriarison, T. Rajoafiarison and J.L. Patton on 23–24 June 2009 at a campsite near the source of Fotsialanana river , western slope of the Makira Massif , Analanjirofo Region, Madagascar (coordinates 15.46675°S, 49.128889°E, 1067 m a.s.l.); ZSM 1754/2010 (ZCMV 12505), adult female, collected by M. Vences, D.R. Vieites, R.D. Randrianiaina, F.M. Ratsoavina, S. Rasamison, A. Rakotoarison, E. Rajeriarison and T. Rajoafiarison on 27 June 2010 at Bemanevika, campsite Atsirakala, Sofia Region, Madagascar (coordinates 14.43061°S, 48.60179°E, 1466 m a.s.l.); as well as five specimens (field numbers ZCMV 11225, ZCMV 11226, ZCMV 11228, ZCMV 11229), all collected in June 2009 by by M. Vences, D.R. Vieites, R.D. Randrianiaina, F.M. Ratsoavina, S. Rasamison, A. Rakotoarison, E. Rajeriarison and T. Rajoafiarison on the western slope the Makira Massif, not examined morphologically but included in the 16S tree ( Fig. 1 ), integrated but still uncatalogued at the UADBA (MZBA) collection (individually identifiable via their field number tags) .

Diagnosis. Assigned to the subgenus Pandanusicola of the genus Guibemantis based on its small body size, phytotelm-dwelling habitats (in Pandanus plants), near-absent webbing between toes, connected lateral metatarsalia, the presence of both inner and outer metatarsal tubercles, intercalary elements between ultimate and penultimate phalanges of fingers and toes (verified by external examination), and molecular phylogeny. The new species is characterized by the unique combination of the following characters: (1) medium size with SVL 25‒29 mm in females, (2) bright green dorsal color with translucent shade, with dense fine purplish-brown spots, (3) distinct brown rostral stripe, (4) absence of white or yellow spots in the inguinal region, (5) absence of webbing on hand and only traces of web at foot, (6) vomerine teeth rudimentary.

The new species is most similar to its sister species G. pulcher , which differs (despite some overlap) by fewer (12–107, mean 42; vs. 47–223, mean 103) and larger (diameter often up to 0.8 mm vs. 0.4 mm) purplish-brown dorsal spots, and a larger and denser purplish-brown band on the flanks which often is adorned centrally by silvery whitish reticulations, as well as by numerous diagnostic nucleotide positions in the mitochondrial 16S rRNA gene.

Description of the holotype. Adult female in good state of preservation. Tissue removed from ventral side of right thigh for DNA extraction, one transverse and two longitudinal cuts on venter for gonad examination. Head longer than wide and slightly wider than body; snout rounded in dorsal, ventral and lateral views; canthus rostralis straight, loreal region flat; nostrils much nearer to tip of snout than to eye, tympanum distinct, 47% of horizontal eye diameter; supratympanic fold poorly expressed, rather straight; vomerine odontophores very poorly expressed and almost not visible, located medially between eye and choanae on either side of head; tongue ovoid, and distinctly bifid at its tip. Arms moderately thin; relative finger length 1<4<2<3, second finger slightly longer than fourth finger; finger discs moderately enlarged and squared off at tips in a rounded “T” shape, no webbing between fingers recognizable, subarticular tubercles visible, unpaired. Hindlimbs moderately thin, foot length 84% of tibia length; lateral metatarsalia connected; inner metatarsal tubercle oblong and recognizable; outer metatarsal tubercle round and only weakly recognizable; only traces of webbing recognizable between toes; relative length of toes 1<2<5<3<4, third toe distinctly longer than fifth; toe discs moderately enlarged. For morphometric measurements see Table 1 .

After 14 years in preservative, dorsally beige with many small spots; these spots are light brown with a weakly recognizable reddish/purple shade. From the snout tip over the nostrils to the eye, and then again from the eye over the tympanum to an area above the forelimb insertions, a distinctly delimited dark brown rostral stripe is present. After the forelimb insertion, this stripe becomes broader, lighter and less distinctly delimited, and forms a brown band on the anterior flanks, dissolving into dense brown spotting on the posterior flanks. The ventral side is uniformly beige without any pattern. In life ( Fig. 7A ) the dorsal side was green with a translucent shade, and the spots and bands were purplish-brown.

Variation. The three morphologically examined paratypes are similar to the holotype. See Table 1 for morphological measurements. Sexual dimorphism cannot be reliably assessed as all genotyped specimens are females. Photos from specimens morphologically assigned to this species from Marojejy and Anjanaharibe-Sud agree with the overall trend of rather small dorsal spots and poorly marked purplish-brown flank patches.

Etymology. The species epithet pulcherrimus is a Latin adjective meaning “most beautiful”, referring to the appealing color pattern of the new species and alluding to the name of its sister species ( G. pulcher ).

Natural history. All known specimens were collected from the leaf axils of Pandanus screw pines in rainforest. Calls, reproductive behavior and larval stages are unknown, but it is likely that the species reproduces in these phytotelms, as does its sister species G. pulcher .

Distribution. Based on genotyped specimens, G. pulcherrimus is known from (1) Hevirina and Fotsialanana source, two nearby sites on the western slope of the Makira Massif, and (2) Bemanevika. Additional specimens morphologically consistent with this taxon are known from three additional localities in northern Madagascar: (3) Anjanaharibe-Sud, (4) Marojejy, and (5) Masoala; these localities need to be genetically verified in the future.

Figures

FIGURE 1. Maximum Likelihood tree based on a 515 bp alignment of the mitochondrial 16S rRNA gene for 66 ingroup samples assigned to G. pulcher, G. flavobrunneus, and G. pulcherrimus sp. nov. Numbers at nodes are bootstrap support values in percent (only shown if>50%). The tree was rooted with G. tornieri (removed graphically to better visualize branch lengths connecting ingroup taxa).

FIGURE 7. Color in life (dorsolateral and ventral views) of specimens of Guibemantis pulcherrimus sp. nov. from (A) Makira West (holotype ZSM 518/2009) and (B,C) Bemanevika (paratype ZSM 1754/2010).

FIGURE 8. Variation in color and pattern in life (dorsolateral views) among specimens tentatively assigned to Guibemantis pulcher (within blue dashed box) and G. pulcherrimus sp. nov. (within red dashed box). Note that most specimens in the plate have not been genotyped and are assigned to the two species based on geographical provenance and color pattern.

FIGURE 9. Preserved holotype (ZSM 518/2009) of Guibemantis pulcherrimus sp. nov.