Contributions to Zoology, 86 (1) – 2017R.G. Bina Perl; Sarig Gafny; Yoram Malka; Sharon Renan; Douglas C. Woodhams; Louise Rollins-Smith; James D. Pask; Molly C. Bletz; Eli Geffen; Miguel Vences: Natural history and conservation of the rediscovered Hula painted frog, Latonia nigriventer

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Introduction

The Hula painted frog (Latonia nigriventer (Mendelssohn and Steinitz, 1943)) was first discovered in the eastern part of the Hula Valley in northern Israel on 22 March 1940 (Mendelssohn and Steinitz, 1943; Fig. 1 A–B) and appears to be strictly endemic to this area. When the draining of the Lake Hula marshes in the 1950s caused the extinction or local disappearance of several species of this area (Dimentman et al., 1992; Goren and Ortal, 1999; Payne, 2012), the dramatic ecosystem change most likely also caused the decline of L. nigriventer. After the then last known individual was collected in 1955 (Steinitz, 1955), the species was the first of 37 anuran species to be officially declared extinct by the IUCN in 1996 (Baillie et al., 2010).

FIG2

Fig. 1. Habitat of Latonia nigriventer. A) Relief map of the Hula Valley (legend shows surface elevation in meters); B) satellite image of the Hula Valley showing the location of the Hula Nature Reserve (indicated by the white circle); C) water body close to the finding sites within the Hula Nature Reserve; D) typical finding site within the Hula Nature Reserve; ditch in Yesod HaMa’ala after (E) and before (F) the vegetation was trimmed by local authorities.

Almost 40 years after the drainage, the Hula Valley was partly re-flooded and signs of ecological restoration were observed (Kaplan et al., 1998; Cohen-Shacham et al., 2011; Kaplan, 2012). Subsequently, in November 2011, a single postmetamorphic individual of L. nigriventer was discovered in the Hula Nature Reserve that protects the last remnant of the former Lake Hula marshes. In the following two years, thirteen more postmetamorphic individuals were captured. All those recently discovered individuals were observed within this same tiny patch of habitat (Biton et al., 2013; SG, YM, EG personal observations).

Painted frogs (Discoglossus) belong to one of the oldest anuran clades (Alytidae) which dates back to the Jurassic. The Hula painted frog was originally described in this genus and had been classified as such until 2013. However, based on recent genetic and osteological analyses the species was found to be a sister to a clade of all remaining Discoglossus and was assigned to Latonia, a genus of fossil giant frogs known from the Miocene through Pleistocene but considered to be extinct since (Biton et al., 2013). The fact that L. nigriventer is the sole surviving species of an ancient clade, and thus alone represents a high proportion of alytid phylogenetic diversity, calls for special attention to ensure its survival. To date, almost nothing is known about the natural history of this ancient, only recently rediscovered frog that still ranges among the rarest amphibians in the world. Apart from the brief tadpole and adult descriptions published by Mendelssohn and Steinitz (1943), the available information on its sister group Discoglossus has remained the only reference to speculate about the natural history of L. nigriventer.

Effective conservation of this unique species requires precise knowledge on its distribution range, basic ecology, and reproductive biology to (i) allow for a definition of adequate conservation priorities targeting aquatic and terrestrial landscape structures in the highly transformed Hula Valley, and (ii) enable future in-situ or ex-situ breeding initiatives. In addition, knowledge about the presence of the chytridiomycete fungus, Batrachochytrium dendrobatidis Long­core, Pessier and Nichols, 1999 (Bd), in the Hula Valley as well as on innate skin defensive mechanisms of L. nigriventer against this pathogen, e.g. mediated through beneficial skin bacteria or antimicrobial peptides (Colombo et al., 2015), are a valuable piece of information for an integrated risk assessment of this species.

Here we have compiled observations and data on multiple aspects of the natural history of L. nigriventer. We also provide the first evidence for the presence of Bd in northern Israel as well as preliminary information regarding the innate immune defences and skin microbial community of L. nigriventer, to aid future conservation management of this critically endangered species.