Hidden by the name: A new fluorescent pumpkin toadlet from the Brachycephalus ephippium group (Anura: Brachycephalidae)

Abstract

Species of Brachycephalus has been having taxonomical issues due its morphological similarity and genetic conservatism. Herein, we describe a new species of Brachycephalus from the south Mantiqueira mountain range and semidecidual forests in the municipalities of Mogi das Cruzes, Campinas and Jundiaí, state of São Paulo, Brazil, based on an integrative approach. It can be distinguished from all species of the B. ephippium species group based on morphological characters (especially osteology and head shape), advertisement call and divergence in partial mitochondrial DNA gene sequences (16S). The new species is genetically similar to B. margaritatus and morphologically similar to B. ephippium. It can be differentiated from B. ephippium by the presence of dark faded spots on skull and post-cranial plates, presence of black connective tissue connective tissue scattered over dorsal musculature, parotic plate morphology, smaller snout-vent length (adult SVL: males 13.46-15.92 mm; females 16.04-17.69 mm) and 3% genetic distance. We also present natural history data and discuss the robustness of the integrative approach, geographic distribution, genetic data, behaviour, fluorescence in ontogeny, and conservation status.

Fig 1. Brachycephalus rotenbergae sp. nov., holotype (HCLP-A 260, adult male, SVL = 13.5 mm).

(A) Dorsal view, (B) ventral view, (C) lateral view of head, (D) ventral view of hand, (E) ventral view of feet.

Fig 2

Variation in specimens of Brachycephalus rotenbergae sp. nov. regarding dorsal shield shape (A-D) and amount of black connective tissue (E-F). (A) HCLP-A 284 (adult female), (B) HCLP-A 285 (adult female), (C) HCLP-A 286 (adult female), (D) HCLP-A 287 (adult male), (E) ZUFMS-AMP 13648 (adult male), (F) ZUFMS-AMP 13649 (adult male).

Fig 3. Brachycephalus ephippium from the species type locality (MNRJ 40806, adult male, SVL 16.26 mm).

(A) Dorsal view, and (B) lateral view of head.

Fig 4. Brachycephalus rotenbergae sp. nov. lightened by a UV flashlight (395 nm wavelength).

Deatil of fluorescence in dorsal and cephalic shields.

Fig 5. Advertisement call of the holotype of Brachycephalus rotenbergae sp. nov. (HCLP-A 260).

Recorded on 5 September 2019 at 08:30 h (FNJV 44409). Spectrogram (above) and oscillogram (bellow).

Fig 6. Cleared and double-stained specimens of Brachycephalus rotenbergae sp. nov.

(A) Dorsal and (B) ventral view of complete skeleton; (C) dorsal, (D) lateral and (E) ventral view of skull with details of mandible and arytenoids cartilage; (F) dorsal view of left hand, arrow indicates ulna and radio fused; (G) dorsal view of left foot, arrow indicates tibiale and fibulare fused; (H) ventral view of pectoral girdle with scapula and supra-scapula deflected; (I) ventral view of spine, arrows indicates vertebrae IV and V fused (in vertebrae body and in transverse process). Vouchers, figs. A, B and E (ZUFMS-AMP 13648, male, SVL 15.89 mm); C, D, F, G, H and I (ZUFMS-AMP 13649, male, SVL 15.79 mm). Acronyms: ac (arytenoids cartilage), clav (clavicle), cor (coracoid), mand (mandible), max (maxilla), nas (nasal), papl (parotic plate), pg (pectoral girdle), pmax (premaxilla), poc (pos orbital crest), prsph (parasphenoid), ptr (pterigoid), pv (presacral vertebrae), pvpl (paravertebral plate), ra (radius), sac (sacrum), sca (scapula), spl (spinal plate), sq (squamosal), ssca (supra-scapula), tpv (transverse process of presacral vertebrae), ul (ulna), uro (urostyle), vm (vomer). Scale bar = 2 mm.

Fig 7. Geographic distribution map for the species of Brachycephalus ephippium group on Google satellite map.

See the species records on S3 Table. Star = type locality of B. rotenbergae sp. nov. ES = state of Espírito Santo, MG = state of Minas Gerais, RJ = state of Rio de Janeiro, SP = state of São Paulo.

Fig 8. Study areas for the natural history observations of Brachycephalus rotenbergae sp. nov.

(A) São Francisco Xavier, Projeto Dacnis, and (B) Reserva das Araucárias.

Fig 9. Relationship between observed Brachycephalus rotenbergae sp. nov. specimens and monthly precipitation (in mm).

Notice that the number of specimens found per field survey reaches zero during months with precipitation under 200 mm.

Fig 10. Natural history observations of Brachycephalus rotenbergae sp. nov.

(A) Inguinal amplexus; (B) An amplected couple of hiding under the juçara palm (E. edulis) root system; (C) Mouth gaping defensive behaviour; (D) One specimen near a yellow/orange mushroom, notice the similarity of color and size; (E) One juvenile specimen; (F) Two juvenile specimens, but the smaller one is darker.