First record of Ischnocnema octavioi ( Bokermann , 1965 ) from São Paulo state , Brazil

We present the first record of Ischnocnema octavioi from São Paulo state, Brazil. Until now, the species was thought to be endemic to Rio de Janeiro, where it was known from fewer than 10 localities. Based on recent data, we recommend that the IUCN Red List status for this species be re-evaluated.

The Atlantic Forest of Brazil is known as one of the richest biodiversity hotspots on Earth.In recent history, 90% of this ancient forest has been lost or become highly fragmented (CEPF 2016).In this ecoregion there are currently 543 species of amphibians, including 529 anurans, of which 88% are endemic, including one endemic family, Brachycephalidae, and many endemic genera (Haddad et al. 2013).The genus Ischnocnema (Brachycephalidae) includes 33 species and was divided into 4 species groups (I.guentheri s.s., I. parva s.s., I. lacteal s.s. and I. verrucosa s.s.), based on morphological and genetic characteristics (Hedges et al. 2008, Canedo & Haddad 2012, Frost 2017).
Ischnocnema octavioi (Fig. 1) is a small terrestrial species of frog with short legs and small digital discs.Dorsum is conspicuously tuberculate with W-shaped mark between front limbs.The iris is red with a vertical black bar.The reproductive strategy of this frog is not well known yet, but it presumably breeds by direct development, as do other similar species in the genus (Bokermann 1965, Canedo et al. 2010).Ischnocnema octavioi inhabits primary and secondary forest up to 1200 m above sea level (a.s.l.) and its major threat is clearing of the forest (Rocha et. al. 2004).According to available literature, almost all previous records of I. octavioi are from the state of Rio de Janeiro, including the type locality, Estrada da Cascatinha, Tijuca Mountains (Bokermann 1965, Costa et al. 2008, Vrcibradic et al. 2008, Siqueira et al. 2009, Siqueira et al. 2011, Vrcibradic et al. 2011, Ouvernay et al. 2012;Bittencourt-Silva & Siva 2013, Almeida-Gomes et al. 2014a, Martins et al. 2014).One exception is the record from Espírito Santo state, but this record probably based on I. verrucosa (Reinhardt & Lütken, 1862), a species with very similar characteristics to I. octavioi but having a different distribution (Dantas & Ferreira 2010).
Our research area was located on the edge of one of the largest remnants of Atlantic forest in the Serra do Mar, Bananal municipality, state of São Paulo, Brazil.During 2013 to 2015, we established a 700 m line transect on private property near Serra da Bocaina National Park and on the edge of Serra do Mar forest fragment.The transect extended from 22°44ʹ05.5ʺS, 044°23ʹ35.8ʺW to 22°43ʹ59.2ʺS, 044°23ʹ19.5ʺW. The elevation was approximately 700 m a.s.l.The forest fragment had the phytophysiognomy of primary forest, with pastures on the southern side and two small pastures, surrounded by forest, on the northwestern and northeastern sides.Cattle graze extensively on the pastures.
The transect started on the edge of the forest and continued inward, crossing one larger (5 m wide) and several smaller (1 m wide) streams.The forest supported high tree density with closed canopy and sparse of undergrowth.The ground was covered by wet leaf litter with decaying wood (Fig. 2); the whole area was rocky and the terrain was often very steep.
The transect was searched for 3 days and three nights consecutively, using non-invasive visual encounter survey (VES) (Heyer et al. 1994).Recorded amphibians were photographed in situ for documentation and identification.
We recorded 3 specimens of Ischnocnema octavioi, each found during a different night survey, but all of them were from a transect section of approximately 30 m in length, located in the central part of the transect.The clearly visible difference in the size and coloration of the 3 specimens rejected the possible repeated observation of the same individual.Specimens were photographed and released.The photographs were then compared to photographs and description of the holotype (Bokermann 1965).Specimens were not sexed.All specimens presented all key characteristics of the species including short hind limbs, unwebbed fingers with slightly differentiated discs, tuberculate dorsum with W-shaped mark, small, visible oval tympanum, prominent nostrils and red iris with a narrow black vertical bar (Bokermann 1965).
There are 4 species morphologically similar to Ischnocnema octavioi, all included in the I. verrucosa species group.
Those species are I. juipoca (Sazima & Cardoso, 1978), I. penaxavantinho (Giaretta, Toffoli, & Oliveira, 2007), I. surda (Canedo & Caramaschi, 2010), and I. verrucosa (Canedo et al. 2010).Ischnocnema juipoca differs from I. octavioi by having a dark yellow iris and no W-shaped shoulder marking (iris red, shoulder mark present in I. octavioi) (Sazima & Cardoso 1978).The iris color in I. penaxavantinho is gray or copper and the bars of the W-shaped mark are not connected (Giaretta et al. 2007).Ischnocnema surda has an indistinct tympanum and distinct white glandular-appearing nuptial pads in males (Canedo et al. 2010).Ischnocnema octacioi most closely resembles I. verrucosa.However, the W-shaped marks of our specimens exhibited large, contrastingly colored tuberculate tips, as described in I. octavioi (Bokermann 1965, Canedo et al. 2010).Identification of our specimens was also confirmed by local specialists Mauricio Almeida-Gomes and Emanuel Teixeira da Silva.We have summarized all key characteristics and differences of species similar to I. octavioi in Table 1.These characteristics confirm that our specimens belong to I. octavioi.
We present the first record of Ischnocnema octavioi from São Paulo state.Our record represents the westernmost locality of this species, more than 100 km west from the type locality and 50 km from the closest known locality.All verified records of the species are from Rio de Janeiro state (Siqueira et al. 2009).One record from the state of Espírito Santo (Dantas & Ferreira 2010) is probably I. verrucosa; no description or photograph was provided.This record's locality is within the distribution area of a very similar species, I. verrucosa, and far from the distribution area of I. octavioi (Canedo et al. 2010).The species is not present in the checklist of amphibian species of Espírito Santo (Almeida et al. 2011), but some authors still report its occurrence in both Rio de Janeiro and Espírito Santo states (Haddad et al. 2013, Frost 2017).Another misidentification was the record from Ilha Grande, Rio de Janeiro state (Rocha et al. 2000(Rocha et al. , 2001)); 2 specimens were described as I. octavioi, but after later examination they were reclassified as I. guentheri (Steindachner, 1864) (Vrcibradic et al. 2008).Nev-   ertheless, Bittencourt-Silva & Siva (2013) still included this Ilha Grande record in their publication on the insular anurans on the coast of Rio de Janeiro state.
According to the literature, there are 9 verified records of Ischnocnema octavioi from different localities described in Table 2 and Figure 3. Five of those records are located within the species' distribution as estimated by Rocha et al. (2004) and 4 of them outside, which indicates that the map is outdated.
Ischnocnema octavioi was recorded on the ground in all previous reports.In our study, 2 specimens were found on the ground, but the third specimen was on a large leaf approximately 30 cm above the ground.The species has never been recorded outside of the forest and probably cannot reproduce outside of the forest (Almeida-Gomes 2014b).All reported specimens were found at or below 800 m a.s.l., with 1 exception (over 1060 m a.s.l.) (Table 2).Maximum elevation for this species has been estimated as 1200 m a.s.l.(Rocha et. al. 2004).The high fragmentation and low density of the forest, and also the areas of high elevation, significantly reduce the available suitable habitat and consequently the distribution of the species, which is now highly fragmented (Fig. 3).Based on these data we recommend that the current IUCN Red List status of I. octavioi (Least Concern) (Rocha et. al. 2004) should be re-evaluated.

CheckFigure 1 .
Figure 1.One of the specimens of Ischnocnema octavioi.Photo by DS.

Figure 2 .
Figure 2. Habitat where the specimens were found.Bananal, Rio de Janeiro state, Brazil.Photo by DS.

Table 1 .
Key characteristics of species similar to Ischnocnema octavioi with highlighted differences in bold.

Table 2 .
List of all known records of Ischnocnema octavioi.