Pelobates balcanicus chloeae, Dufresnes, Christophe, Strachinis, Ilias, Tzoras, Elias, Litvinchuk, Spartak N. & Denoel, Mathieu, 2019

Dufresnes, Christophe, Strachinis, Ilias, Tzoras, Elias, Litvinchuk, Spartak N. & Denoel, Mathieu, 2019, Call a spade a spade: taxonomy and distribution of Pelobates, with description of a new Balkan endemic, ZooKeys 859, pp. 131-158 : 144-148

Pelobates balcanicus chloeae ssp. nov.

Type locality.

Strofylia meadows, near the village of Metochi, Peloponnese, Greece (38.1239°N, 21.3858°E, 1 m a.s.l.). Coastal sandy meadows with shallow ponds (Fig. 5).

Holotype.

NHMC 80.2.15.10, adult female captured on December 10th 2018 by CD, IS and ET at Strofylia meadows, Greece (38.1239°N, 21.3858°E, 1 m a.s.l.); subsequently deposited at the Natural History Museum of Crete (NHMC); mitochondrial cyt-b haplotype BAL19 ( Dufresnes et al. 2019b). Full measurements are available in Table 2 and photographs in Figure 5. Large specimen (SVL = 78.7 mm) with the head narrower than the body, ending by a rounded snout; nostrils closer to each other’s than from the eyes; forehead flat, as viewed from the side, with large interorbital; tympanum invisible; vomerine teeth present. Large, bulging eyes (7.2 mm of diameter) with vertical pupil and a dark-golden iris. Legs relatively short (92 mm), 1.2 times the size of the body. Five partially webbed toes; webbing formula: I 1-1+ II 1-2 III 1-2+ IV 3-1+ V; relative lengths from inner to outer toes: 4>3>5>2>1; large and long rounded (blade-shaped) metatarsal tubercle ( “spade”), whitish; subarticular tubercles indistinct. Strong arms with four unwebbed fingers; palm tubercles visible, oval. Ventral and dorsal skins smooth, although the latter bears scattered warts. Coloration in life: ventrum glossy white, bluish near the limbs; dorsum light gray with prominent green-brown reticulated patches featuring orange dots, notably at the armpits; head darker, with a horizontal brown line running between the eyes. Changes of coloration in ethanol: dorsum less contrasted; fainted orange dots.

Paratype.

NHMC 80.2.15.11, adult female captured on December 10th 2018 by CD, IS and ET at Strofylia meadows, Greece (38.1239°N, 21.3858°E, 1 m a.s.l.); subsequently deposited at the Natural History Museum of Crete (NHMC); mitochondrial cyt-b haplotype BAL20 ( Dufresnes et al. 2019b). Full measurement and post-mortem pictures are provided in Table 2 and Figure 5, respectively.

Diagnosis.

Supposedly similar morphologically to the nominal subspecies and reliably diagnosed only by molecular data. So far studied from the type locality only (Strofylia). Like the nominal subspecies, Pelobates balcanicus chloeae is a large spadefoot with whitish metatarsal spades, a flat skull and incomplete webbing on the hind feet (Fig. 4). It also shares general characteristics of the genus, i.e. stocky built, smooth skin and vertical pupil; males bear oval protuberances on the arms, absent in females. The dorsum coloration is generally light gray, sometimes yellow, covered with dark green-brown reticulate patches and variable orange dots (Fig. 4). From our own observations, the color patterns seem to slightly differ from the nominal subspecies (Fig. 4). In P. b. chloeae , the green patches are small and numerous (fewer but larger patches in the nominal subspecies); dots are usually orange (more reddish in the nominal subspecies) and located inside the green patches (randomly distributed in the nominal subspecies). The ventrum and limbs are glossy and slightly bluish (rather pale whitish in the nominal subspecies). Moreover the snout of P. b. chloeae appears shorter and blunter than the nominal subspecies. These suspicions will need to be assessed by formal phenotypic analyses. At the type locality, the SVL of adults averaged 71.5 mm (range: 62-84; n = 12 individuals, both sexes combined). The mating call and the tadpole are yet to be described and diagnosed. The karyotype has not been documented. As shown in Table 1, P. b. chloeae differs from the nominal subspecies by 2.8% at mtDNA and 0.02% at nuclear DNA ( Dufresnes et al. 2019b).

Taxonomic status.

Following Dufresnes et al. (2019b), we raise the population(s) from the Peloponnese as a distinct P. balcanicus subspecies based on nuclear and mitochondrial phylogenetic data, but refrain a specific status from current data, due to the relatively young evolutionary divergence (~2 My) and potential introgression with the nominal subspecies.

Etymology.

No name is available for spadefoots from the Peloponnese or Greece in general. We hence attribute it a new nomen, Pelobates balcanicus chloeae , as a reference to the young daughter of CD, Chloé, who played a decisive role in guiding his research towards European biogeography and herpetology. Moreover, “Chloé” is an ancient Greek name ( “Χλόη”) designating the young green grass spurring from the ground in spring, reminiscent of spadefoots unearthing themselves to breed in mass. The name is also associated with Dimitra (Δήμητρα), the Ancient Greek goddess of agriculture who protected traditional farmlands in which so many amphibians used to thrive.

Distribution.

From current knowledge, this subspecies is endemic to the Peloponnese in southern Greece ( Dufresnes et al. 2019b) (Fig. 1); it was so far genetically confirmed from its type locality only. Historically (1980s), there were records of spadefoots all over the Peloponnese, except in the three southern peninsulas ( Böhme 1975; Eiselt 1988; Sofianidou 2012). Nowadays, the two known Pelobates localities are restricted to the central (Tripoli) and north-western (Strofylia) areas. Consequently, it is likely that there are only few populations left for this subspecies. It is not excluded that its range extends to Central Greece, where potential populations have not been examined; one sample from Kallithea Elassonos (Thessaly, Greece) bore trace of introgression by P. b. chloeae , suggesting past or present contact ( Dufresnes et al. 2019b).

Ecology.

Never studied as such, but this subspecies most likely shares a similar ecology as the nominal subspecies ( P. b. balcanicus ). Inhabits open, flat, lowland areas with soft sandy soil near shallow ponds or ditches with aquatic vegetation for breeding, as described for P. balcanicus ( Dufresnes 2019). Mostly nocturnal and semi-fossorial: comes out of the ground for foraging and breeding during / right after heavy rains. Hence it can be observed in high numbers during winter-spring showers; ET counted>70 individuals (mostly juveniles) in 15 min of search in late-October 2018 at the type locality; usually active around 13-20 °C, but also as low as 7 °C (ET pers. obs.).

Diversity.

Our P. b. chloeae samples featured the lowest nuclear genetic diversity recorded across the entire ranges of P. balcanicus and P. syriacus ( Dufresnes et al. 2019b). This implies that the Strofylia population and perhaps the subspecies as a whole have been heavily bottlenecked. Two mtDNA haplotypes co-occur ( Dufresnes et al. 2019b). Genetic studies are urgently needed to assess the range and diversity of this regional endemic.

Conservation Status - Ioannidis and Mebert (2011) mentioned road casualties at the type locality of this taxon, one of few extant populations. Although not evaluated yet, this taxon is clearly threatened according to IUCN criteria; given the narrow extent of occurrence (EOO), it should be listed as Critically Endangered (CR).

Identification key

Based on our updated overview of the taxonomy and distribution of Pelobates , we hereby provide a key to summarize the main discriminating features within this group. Because several taxa are cryptic and lack diagnostic phenotypic differences, geographic origin remains an essential information.