Echinotriton (Echinotriton) raffaellii, Dufresnes & Hernandez, 2023

Dufresnes, Christophe & Hernandez, Axel, 2023, Towards completing the crocodile newts’ puzzle with all-inclusive phylogeographic resources, Zoological Journal of the Linnean Society 197, pp. 620-640 : 633-636

ECHINOTRITON (ECHINOTRITON) RAFFAELLII HERNANDEZ & DUFRESNES SP. NOV.

( FIG. 9 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: E88B336D-5B43-41BC-A210-1C30A1564C91.

Identity and diagnosis: A robust newt characterized by a series of 12–13 conspicuous spiny costal warts with one to three extra rows of smaller warts next to the vertebral ridge ( Fig. 9 ). Background coloration is uniformly black, except for the underside of the tail, the cloacal region, the feet soles and the tips of the costal warts, which are yellow-orange to reddish.The fifth toe is rudimentary. The vomero-palatine teeth are V-shaped in two longitudinal series that meet in front. Echinotriton raffaellii is the sister-species to E. andersoni , with which it was previously confounded. Specifically, it corresponds to the Echinotriton populations inhabiting the Amami Island group (yellow, orange and red squares in Fig. 2 ), often referred to as the ‘Amami clade of E. andersoni ’ in the literature. True E. andersoni should be restricted to the populations inhabiting the Okinawa Island group (pink and purple squares in Fig. 2 ), as per the type locality of this taxon (‘ Okinawa, Japan’). Based on our mitochondrial phylogeny, E. raffaellii diverged from E. andersoni in the Late Miocene (~7 Mya). It features 2.7% sequence differentiation at 16S, 6.4% at ND2 and 7.9% at Cytb. In addition, E. raffaellii bears private nuclear alleles at intron loci ( Fig. 5 ) and unique microsatellite profiles that suggest acute nuclear differentiation without recent genetic introgression ( Igawa et al., 2020). Besides molecular characters, E. raffaellii differs from other Echinotriton (including E. andersoni ) by a moderately smaller size (both in TTL and SVL) and a shorter tail. The head is more distinctively triangular. The body is covered by brightly coloured, anteriorly directed projections, and the costal spiny warts feature bright yellow-orange/reddish tips.

Holotype: MVZ: Herp :232187, adult male collected in Tokunoshima , Ryukyu Archipelago , Kagoshima Prefecture, Japan, by Theodore Papenfuss in January 2001 (depicted in Fig. 9 ), and curated at the Museum of Vertebrate Zoology , University of California, Berkeley, USA. The mitogenome of this specimen was sequenced (Weisrock et al., 2006) and is featured in our phylogeny (red square in Fig. 2 ).

Description of the holotype: Good state of preservation in spite of the torn ventral cavity ( Fig. 9 ). Slim newt (TTL: 110.3 mm) with a strongly granulated skin and a laterally compressed tail (TAL: 46.0 mm), 1.5 × times shorter than the body (SVL: 64.3 mm); distinctive triangular head (HW: 17.7 mm, HL: 16.5 mm, HD: 23.7 mm), much larger than body (CW: 12.3 mm); short snout (SL: 6.1 mm), with nostrils slightly closer from each other’s (IN: 4.6 mm) than from the eyes (ON: 5.1 mm); large eyes (ED: 4.4 mm) laterally disposed (IC: 7.7 mm); vertebral ridge prominent; 12 pointy lateral glandular warts, disposed from axilla to the tail basis; forelimbs (AL: 14.2 mm) of similar size than hind limbs (PL: 14.1 mm) and widely spaced (AX: 38.6 mm); four fingers and five toes (fifth one rudimentary), with no visible webbing; cloaca distinct, with longitudinal vent slit; coloration includes a dark mate background, with orange colours only at the lateral warts, fingers and toes, the cloaca region and the underside of the tail.

Paratype: MZL–46961, specimen born in captivity, descending from adults collected on Tokunoshima by C. B. Fleck and which identity was confirmed by 16S barcoding. Curated at the Cantonal Museum of Zoology of Lausanne .

Etymology: We coin the new name Echinotriton (Echinotriton) raffaellii as a tribute to Jean Raffaëlli, French naturalist and world expert of newts and salamanders.

Common names: Raffaëlli’s spiny crocodile newt (English), Echinotriton de Raffaëlli (French) .

DiƲersity and distribution: Echinotriton (E.) raffaellii is only known from three islands of the Amami Island group in the northern part of the Ryukyu Archipelago, Japan: Tokuno (the type locality), Amami and Uke. Genetic analyses suggest mitochondrial and nuclear differentiation between these populations ( Igawa et al., 2020), reflecting recent disconnections after the disappearance of land bridges that connected the islands during the last glaciation ( Dufresnes & Litvinchuk, 2022: fig. 45) .

Natural history: The species inhabits a mosaic of grasslands, forests and sugarcane plantations (3–374 m a.s.l.), where it is usually found near water bodies, hidden under rocks or in leaf litter. Breeding occurs from February to June and is exclusively terrestrial. During courtship, the male takes a semicircular posture while rubbing the flanks of the female with its head, then deposits a spermatophore on the ground that the female eventually picks up. Clutches of eggs are then spawned under pine needles, dead leaves and in humus close to ponds and small streams, where hatching larvae are carried away by heavy rains.

ConserƲation: Japanese Echinotriton (as ‘ E. andersoni ’) are categorized as ‘Endangered’ (EN) class B 1 in the IUCN Red List and as ‘Vulnerable’ (VU) at the national level ( Environment Agency of Japan, 2000). The species further appears on CITES appendix II – international level ( CITES, 2021). The prefectures of Kagoshima and Okinawa have afforded them the rank of ‘natural monument’. Hence, E. (E.) raffaellii is undoubtedly a rare and endangered species. The major threats include: international trafficking, which involves illegal poaching and exports to China, Hong Kong, Europe and the United States; predation by the invasive Java mongoose UrƲa jaƲanica (Geoffroy Saint-Hilaire, 1818); and deforestation of the Ryukyus for sugarcane plantations and urbanization since the 1960s (especially on Tokuno).

Figures

Figure 2. Phylogeography of crocodile newts part I: genus Echinotriton and subgenus Tylototriton. The phylogenetic position and geographic distribution of each lineage is detailed by coloured symbols on the tree and the corresponding maps. Type localities of described taxa are indicated by stars. For T. Ʋerrucosus, we highlighted the paraphyletic position of sequences attributed to T. shanjing, as well as its type locality with asterisks.

Figure 5. Nuclear phylogeny of 27 crocodile newt species based on 3.2 kb combining four nuclear introns (POM-C, RAG1, BDNF and NCX1). Species are symbol-coded by genera and colour-coded by subclades as in the mitochondrial phylogeny (Fig. 1). Photos: E. maxiquadratus and T. pseudoƲerrucosus (credits: AH).

Figure 9. Appearance of Echinotriton (Echinotriton) raffaellii sp. nov. Top: live individual observed at the type locality (credits: AH); bottom: the holotype MVZ:Herp:232187 (credits: MVZ).