Saturday, December 12, 2015

[Herpetology • 2015] Dendropsophus counani • A New Dendropsophus Fitzinger, 1843 (Anura: Hylidae) of the parviceps group from the Lowlands of the Guiana Shield

Dendropsophus counani 
 Fouquet, Orrico, Ernst, Blanc, Martinez, Vacher, Rodrigues, Ouboter, Jairam & Ron, 2015


Many Amazonian frog species that are considered widely distributed may actually represent polyspecific complexes.. A minute tree frog from the Guiana Shield originally assigned to the allegedly widely distributed Dendropsophus brevifrons proved to be a yet undescribed species within the D. parviceps group. We herein describe this new species and present a phylogeny for the D. parviceps group. The new species is diagnosed from other Dendropsophus of the parviceps group by its small body size (19.6–21.7 mm in males, 22.1–24.5 mm in females), thighs dorsally dark grey with cream blotches without bright yellow patch, absence of dorsolateral and canthal stripe, and an advertisement call comprising trills (length 0.30–0.35 s) composed of notes emitted at a rate of 131–144 notes/s, generally followed by click series of 2–3 notes. Its tadpole is also singular by having fused lateral marginal papillae and absence of both labial teeth and submarginal papillae. Genetic distances (p-distance) are >5.3% on the 12S and >9.3% on the 16S from D. brevifrons, its closest relative. This species occurs from the Brazilian state of Amapá, across French Guiana and Suriname to central Guyana and is likely to also occur in adjacent Brazilian states and eastern Venezuela. This species is not rare but is difficult to collect because of its arboreal habits and seasonal activity peaks.

Keywords: Amphibia, Amazonia, Anura, conservation, endemism, taxonomy, widespread taxa

Etymology. The specific epithet refers to the utopic and short-lived “independent state of Counani” which was founded by French settlers and existed from 1886 to 1891 at the border of what is now French Guiana and the Brazilian Amapá State. It was governed by the self-proclaimed “Gros 1er”. A new Dendropsophus Fitzinger, 1843 (Anura: Hylidae) of the parviceps group from the lowlands of the Guiana Shield.

Distribution,  ecology,  and  conservation.  In  addition  to  the  material  examined,  above  13  additional  occurrences in French Guiana were retrieved from the personal observations of various persons (Appendix 3), as well as three in Suriname (Ouboter & Jairam 2012; pers. obs.), two in Amapá (acoustic record from J. Dias Lima; pers. obs.) and one in Guyana (Cole et al. 2013) (Fig. 1). The absence of previous records in Amapá (Dias Lima 2008)  and  Northern  Pará  (Avila-Pires  et  al.  2010)  is  noteworthy.  Lima  et  al.  (2006)  provide  details  on  Dendropsophus brevifrons from Reserva Adolfo Ducke but the species probably belongs to the D. microcephalus group. Our  identification  is  based  on  the  visual  examination  of  the  pictures,  the  video  record  provided,  and  personal examination by one of us (VGDO). 

This  species  inhabits  primary  and  secondary  forest  and  is  encountered  only  when  breeding,  in  temporary  ponds, as well as flooded parts of stream and river beds after heavy rain. Males call on vegetation (on small branches or leaves) overhanging or nearby water. They often start calling in the late afternoon and continue at night. Outside these reproduction activity events, the species likely dwells in the canopy and thus remains difficult to detect. Even when active, calling males often remain high in the trees and descend only after heavy rains. This is likely the cause for the failure to detect the species during previous surveys undertaken in Amapá (Dias Lima 2008) and Northern Pará (Ávila-Pires et al. 2010). Clutches (50–79 eggs) are deposited on vegetation above water and tadpoles drop from the gelatinous clutch after a few days. Six days before hatching, clutches have already a typical elongated shape and exhibit drip-tips at the distal end (Fig. 6d).

Dendropsophus counani occurs from the Brazilian state of Amapá across French Guiana and Suriname to Central Guyana and is likely to extend its range into adjacent Brazilian states and eastern Venezuela. The single specimen from Belém (KU127846) that was examined by Duellman & Crump (1974) cannot be unambiguously identified as D. counani sp. nov. This specimen, which was not included in the type series by Duellman and Crump (1974), was examined by us via pictures provided by the curators of the herpetological collection of KU and is very similar to specimens of D. counani sp. nov. i.e. from the other side of the Amazon River. Nevertheless, some differences exist (e.g. white flash mark on flanks and on dorsal side of legs are quite different). Given that there is only a single individual available from south of the Amazon River and molecular data is missing, it is difficult to draw any conclusions about the identity of the Belém population.

In French Guiana, Dendropsophus counani sp. nov. occurs throughout the territory and can be locally abundant when breeding, as it is probably also the case in Suriname and Amapá. In Guyana, throughout the entire study period, the species appeared only sporadically (only on very few days/nights), very localized (only two localities), and in low densities (only 24 calling males during 393.5 hrs of standardized visual and acoustic transect sampling, or 0.06 individuals/transect hour) (Ernst et al. 2006; Ernst & Rödel 2008). 

Both  (B1)  the  extent  of  occurrence  (>20.000  km2)  and  (B2)  the  area  of  occupancy  (>2000  km2) of  Dendropsophus counani are largely over the threshold of the IUCN threatened categories. Moreover, its range lies in the Guiana Shield, which is relatively well preserved, the range of D. counani is putatively continuous and no noticeable decline has been observed nor is expected in the upcoming years. Therefore, the species should be listed as Least Concern. 

Fouquet, Antoine, Victor G. D. Orrico, Raffael Ernst, Michel Blanc, Quentin Martinez, Jean-pierre Vacher, Miguel T. Rodrigues, Paul Ouboter, Rawien Jairam and Santiago R. Ron. 2015. A new Dendropsophus Fitzinger, 1843 (Anura: Hylidae) of the parviceps group from the Lowlands of the Guiana Shield. Zootaxa. 4052(1): 39–64.  DOI: 10.11646/zootaxa.4052.1.2