Spinomantis mirus, Sabino-Pinto & Rakotoarison & Bletz & Edmonds & Glaw & Vences, 2019

Sabino-Pinto, Joana, Rakotoarison, Andolalao, Bletz, Molly C., Edmonds, Devin, Glaw, Frank & Vences, Miguel, 2019, A new species of the Spinomantis bertini species complex (Anura: Mantellidae) from Pic d’Ivohibe Special Reserve (Madagascar), Zootaxa 4656 (1), pp. 133-142 : 137-140

Spinomantis mirus sp. nov.

urn:lsid:zoobank.org:act:73F4C4DA-B47B-4EDC-9BD0-8A3B0ED08BEA

Remark. This species has previously been referred to S. sp. Ca12 by Vences et al. (2017).

Holotype. ZSM 818 /2014 ( ZCMV 14764 ), adult male ( Fig. 2 , no picture in life available), from a primary forest along a stream in Pic d’Ivohibe Special Reserve (-22.49833, 46.95917, 1,695 m above sea level), southeastern Madagascar, collected on 10–11 November 2014, by A. Rakotoarison. M.C. Bletz, D. Edmonds & F. Randrianasolo.

Paratypes. UADBA-A 61689 ( ZCMV 14765 ) , adult male, UADBA-A 61668 ( ZCMV 14752 ) , ZSM 817 / 2014 ( ZCMV 14753 ) and ZSM 819 / 2014 ( ZCMV 14770 ), adult females ( Fig. 3 ), all collected by the same collectors during the same dates . UADBA-A 61668 and ZSM 817 /2014 were collected at a lower elevation (-22.49667, 46.95644, 1,506 m). UADBA-A 61689 and ZSM 819 / 2014 were collected at the same locality data as the holotype .

Diagnosis and comparisons. The new species is assigned to the genus Spinomantis (Mantellidae) based on (1) phylogenetic affinities to S. bertini and S. beckei , (2) presence of intercalary elements between ultimate and penultimate phalanges of fingers and toes (verified by external shape of digits), (3) presence of distinct femoral glands of type 1 ( Glaw et al. 2000) in males, (4) outer metatarsal tubercle present, (5) maxillary teeth present, and (6) adults living along streams in rainforest.

Within Spinomantis , the new species is distinguished by a combination of the following characters: (1) body size, adult male SVL 24 mm and adult female SVL 25−27 mm; (2) lighter color of the flank with distinct mottling of whitish and dark brown and tri-color banding on the legs; (3) thick frenal stripe; and (4) a dorsal color pattern with large and distinct brown dots. Furthermore, it differs from all other Spinomantis species by a substantial divergence of 8.1–9.8% uncorrected pairwise distance in a fragment of the 16S gene.

Spinomantis mirus sp. nov. can be distinguished from other Spinomantis species not belonging to the S. bertini species complex by numerous morphological characters. Based on comparative data from Glaw & Vences (2007) and Cramer et al. (2008), S. mirus sp. nov. differs from the fully arboreal species S. aglavei , S. fimbriatus , S. massi , S. nussbaumi , S. peraccae , S. phantasticus , and S. tavaratra by terrestrial habits and a smaller body size (SVL 24−27 vs. 31−56 mm); from S. aglavei , S. fimbriatus , S. massi , S. phantasticus , and S. tavaratra by a smooth skin without dermal spines or flaps; from S. elegans by a much smaller body size (SVL 24−27 vs. 50−60 mm) and ab- sence of a clearly delimited ocellated dorsal pattern (vs. presence); from S. guibei by smaller body size (SVL 24−27 vs. 29−40 mm) and a mainly brown (vs. green) color pattern; from S. microtis by smaller body size (SVL 24−27 vs. 30−48 mm), much smaller terminal discs on fingers and toes, and smooth skin; and from S. brunae by smaller size (SVL 24−27 vs. 32−35 mm) and absence of gold and black mottling dorsally (vs. presence).

In relation to other species of the S. bertini species complex, S. mirus sp. nov. differs from both S. bertini and S. beckei in the lighter color of the flank with more distinct mottling of whitish and dark brown, tri-color banding on the legs (dark brown, light yellow and light brown), and a dorsal color pattern with more distinct brown dots. Spinomantis mirus sp. nov. further differs from S. bertini by having a slightly larger body size (female SVL 25−27 vs. 21−25 mm, male measurements not available for S. bertini ), a more muted pale yellowish-green color on dorsum, legs and head, a dorsolateral line with light yellow borders, a frenal stripe more whitish (vs. greenish-yellow), and more extensive and distinct mottling on the venter. Spinomantis mirus sp. nov. differs from S. beckei by having slightly smaller femoral glands (ratio FGL/SVL 0.14–0.22 vs. 0.19–0.24 mm), a lighter colored and spotted (vs. dark and mottled) coloration on the dorsum, more distinct banding on the legs, and by having a thicker frenal stripe ( Fig. 3 ).

Description of the holotype. Specimen in good condition, tongue excised as tissue sample. Snout−vent length 24.3 mm, for further measurements see Table 1. Slender body; head longer than wide, and as wide as body; rounded to somewhat angular snout in dorsal and lateral views, protuberant nostrils inserted laterally, closer to the tip of snout than to eye; distinct canthus rostralis, arched; concave loreal region; distinct tympanum, rounded, its diameter 62% of eye diameter; small supratympanic fold; no vomerine teeth, reduced maxillary teeth; large choanae, oval. Slender arms; single subarticular tubercles; no finger webbing; relative length of fingers 1<2<4<3; finger discs enlarged; nuptial pads absent. Slender hindlimbs; tibiotarsal articulation reaches the tip of the nostril when hindlimb is adpressed along the body; single subarticular tubercles; lateral metatarsalia partly connected; inner metatarsal tubercle distinct, outer metatarsal tubercle not recognizable; reduced webbing, formula 1(1), 2i (1.5), 2e(1), 3i (2.5), 3e(2), 4i (3), 4e(3), 5(2); relative length of toes 1<2<3=5<4. Skin on the upper surface smooth, without folds or ridges. No distinct enlarged tubercles in the cloacal region; ventral skin smooth. Small femoral glands of type 1 sensu Glaw et al. (2000), distance between femoral glands 1.2 mm.

After five years in preservative, the head appears rather uniformly brown with some darker brown spotting or mottling. The dorsum has mottling similar to the head but a lighter tone. There is a moderately distinct dark, almost black, dorsolateral stripe with a thin white line bordering the top, which runs from the nostril to the inguinal region. The flanks appear lighter in color than the dorsum. The limbs retain a distinct banding pattern.A thin white line runs along the upper lip. Ventrally, brownish with numerous white dots and small markings on chest and venter, markings are less evident on the chin and pectoral region. Ventral sides of thighs, shanks, and feet are brown with contrasting white blotches. Femoral glands are brown, contrasting with the mottled appearance of the thighs. Ventral sides of hands and feet are uniformly brown.

The coloration in life of the holotype is unknown because it was not photographed in the field.

Variation. The paratype specimens ( Fig. 3 ) are one male and three females (see Table 1 for additional measurements) and strongly resemble the holotype. Males are smaller than the females ( SVL 24 vs. 25‒27 mm) and have femoral glands but do not show other obvious sexual dimorphism in external morphology or coloration. Compared to the holotype, the paratypes vary in the size and shape of mottling (resembling more dots than mottling) both dorsally and ventrally, the distinctness of banding on the legs, and the intensity of the white border of the dorsolateral line. In life, individuals had a pale yellowish green dorsal and head coloration with well-defined brown dotting; brown dotting appeared smaller on the head; legs had tricolor banding with dark brown, pale yellow and light brown; banding on the arms was less distinct; thick pale greenish-white frenal stripe and dark brown dorsolateral line with light greenish-yellow borders were present; flank was mottled with white and brown; venter had varying degrees of white and brown mottling; pale greenish-yellow iris matching the color of the borders of the frenal stripe ( Fig. 3 ).

Natural history and distribution. Spinomantis mirus sp. nov. was found in primary forests both during day and night along small rivers. Males were not calling when collected and vocalization remains unknown. The species is only known from Pic d’Ivohibe Special Reserve ( Fig. 1 ).

Etymology. The specific epithet is a Latin adjective (masculine form) meaning “surprising.” The new species is named after the unexpected events that occurred during its finding, such as encounters with police that confused the team with cattle thieves, and tiresome hiking after searching in vain for the trails left by previous expeditions.

Figures

FIGURE 1. A) Maximum Likelihood phylogenetic tree based on 435 base pairs of the mitochondrial 16S rRNA gene depicting relationships within the Spinomantis bertini complex. Numbers at nodes are percentages of bootstrap pseudoreplicates. Grey shading marks the new species. The inset map shows approximate location of the collecting sites of specimens represented in the tree. Scale bar in substitutions per site. Adapted from Vences et al. (2017). B) Haplotype networks reconstructed from DNA sequences of the nuclear genes KIAA1239 (left) and RAG-1 (right), for the three named species of the S. bertini complex.

FIGURE 2. Dorsal and ventral views of preserved holotype of Spinomantis mirus sp. nov., ZSM 818/2014 (ZCMV 14764). All scale bars correspond to 5 mm.

FIGURE 3. Lateral and ventral views of the female paratypes UADBA-A 61668 (ZCMV 14752) (A−B), and ZSM 817/2014 (ZCMV 14753) (C−D) of Spinomantis mirus sp. nov. from Pic d’Ivohibe in life.