Echinotriton raffaellii Dufresnes & Hernandez, 2022

Nishikawa, Kanto, Matsui, Masafumi & Tominaga, Atsushi, 2022, Morphological and taxonomic reexamination on a crocodile newt recently described from Japan (Urodela, Salamandridae, Echinotriton), Zootaxa 5196 (2), pp. 223-234 : 226-230

Echinotriton raffaellii Dufresnes & Hernandez, 2022

[Japanese name: Amami-ibo-imori]

( Fig. 3A, B, C )

Tylototriton andersoni: Tago 1931 , 68 (part)

Echinotriton andersoni: Nussbaum & Brodie 1982 , 321 (part).

Holotype. MVZ ( Museum of Vertebrate Zoology , University of California, Berkeley, USA): Herp:232187, adult male from Tokunoshima, Ryukyu Archipelago, Kagoshima Prefecture, Japan. The original description noted that it was collected by Theodore Pappenfuss in January 2001, but actually it was collected by a local collaborator of Masafumi Matsui (his name was written on the specimen tag of the holotype: see Fig. 9 of Dufresnes & Hernandez [2022]), who sent it to Theodore Pappenfuss for a collaborative project.

Paratype. MZL ( Cantonal Museum of Zoology of Lausanne)–46961, sex-unknown individual and derived from adults collected from Tokunoshima by C. B. Fleck and grown in captivity. No more information and measurement of the specimen was shown in the original description .

Specimens referred in the present paper. Amamioshima: KUHE 8893 and 8894 from unknown locality (two males) ; KUHE 8367 from Amami, KUHE 8895 from unknown locality, NSMT H00209 and H04051 from Uken, OMNH Am 9582–9593, 9783 (17 females) . Ukejima: KUHE 50692 from Setouchi (one male) , KUHE 50691 and 50693 (two females) . Tokunoshima: KUHE 13969 and 13970 from unknown locality, KUHE 49868 from Amagi (three males) ; KUHE 8885–8887 from unknown locality, KUHE 13971–13973 , 49800 , 49801 , OMNH Am 9773, 9904, 9919, 9920 from Amagi, NSMT-H-01252 from Amagi (18 females) .

Diagnosis. A medium-sized species of Echinotriton (adult SVL 55.3–71.1 mm in males and 55.3–82.2 mm in females), breeding in the still water; dorsum black with numerous small granules; reddish, dark orangish to yellowish marking on quadrate spine, rib nodules, tips of fingers and toes, palms and soles, vent, and underside of the tail; limbs and tail long and thin; tips of fore- and hindlimbs adpressed on body greatly overlapped (overlap of 11.8%AGD in males and 10.0%AGD in females); fifth toe ill-developed; ova large, pigmentless; most similar to E. andersoni , but with smaller body size, relatively longer eyelid and finger and toe, and relatively narrower vomerine tooth series. Echinotriton raffaellii is genetically closer to Japanese E. andersoni than to Chinese E. chinhaiensis and E. maxiquadratus . All of these four species are clearly separated molecularly.

Color. In life, the dorsum black in ground color with reddish, dark orange to yellow marking on quadrate spine, rib nodules, tips of fingers and toes, palms and soles, vent, and underside of the tail. Underside of body nearly same as dorsum ( Fig. 3A, B ). In preservative, reddish, dark orange to light yellow marking tending to fade.

Variation. Morphometric data are summarized in Table 1 . Males (n=8) were significantly smaller in body size than females (n=37). For proportion, males have significantly larger values than females in head length (HL, median=28.9%SVL vs. 25.9%SVL), head width (MXHW, median=30.2%SVL vs. 28.8%SVL), snout length (SL, median=10.8%SVL vs. 9.5%SVL), eye-nostril length (ENL, median=6.8%SVL vs. 5.9%SVL), interorbital distance (IOD, median=10.9%SVL vs. 9.9%SVL), upper eyelid length (UEL, median=7.5%SVL vs. 6.5%SVL), orbit length (OL, median=4.9%SVL vs. 4.3%SVL), vent length (VL, median=7.3%SVL vs. 6.4%SVL), basal tail height (BTAH, median=10.6%SVL vs. 9.8%SVL), maximum tail height (MXTAH, median=11.0%SVL vs. 10.2%SVL), 3 rd finger length (3FL, median=5.9%SVL vs. 5.6%SVL), and width of vomerine tooth series (VTW, median=8.5%SVL vs. 6.9%SVL). Females have significantly larger values than males in trunk length (TRL, median=74.1%SVL vs. 71.1%SVL). For geographic variation, the Amami population had significantly larger SVL and lower tail mid-height than the Tokunoshima one in female. In addition, the Tokunoshima population tended to show brighter markings on the quadrate spine and rib nodules, and longer quadrate spine than the Amami population.

Eggs. As shown in Fig. 4A , eggs of this species are greyish in color and comparatively large, with a diameter of 3.0 ± 0.1 mm (n=25).

Larvae. According to Utsunomiya & Utsunomiya (1977), full-grown larva (fully grown larva at St. 59 in Okada & Ichikawa [1947]) has SVL 19.0 mm and TAL 22. 0 mm (both probably mean values). Body black, tail fin dotted with black and costal grooves distinct ( Fig. 3C ).

Range. Amamioshima, Ukejima, and Tokunoshima islands of the Amami Island group, in Kagoshima Prefecture, Western Japan ( Fig. 1 ).

Morphological Comparisons. Echinotriton raffaellii is distinct from all other congeners ( E. andersoni , E. chinhaiensis , and E. maxiquadranus ) by having a combination of the characters of dorsal rib, body shape, and skin texture.

Echinotriton raffaellii is different from two Chinese congeners of E. chinhaiensis and E. maxiquadranus by the presence of bony projection on dorsal rib, thick body, and rough skin with many granules (vs. absence of bony projection on dorsal rib, flat body, and relatively smooth skin without granules in E. chinhaiensis and E. maxiquadranus ). Echinotriton raffaellii is most similar to another Japanese species, E. andersoni , but different from the species by relatively flat head and body, prominent quadrate spine and rib nodules, rough skin, slightly smaller body size, relatively longer eyelid, relatively longer digit and relatively narrower vomerine tooth series.

Natural history. The spawning season of the present species is from early February to late June (peak is from middle March to early April), but may vary by year depending on rainfall ( Utsunomiya et al. 1978). The species oviposits on slopes near waterfronts of the small ponds and wetlands but not directly in the water ( Fig. 4 ), 0–80 cm above the water surface ( Utsunomiya 1999). Females were observed to push their eggs into mud with the snout ( Utsunomiya et al. 1978). Adults, especially females, are sometimes found far from breeding waterbodies. Metamorphs feed various invertebrates including earthworms, snails, and centipede ( Honda et al. 2011).

Conservation. All populations are protected as Echinotriton andersoni by Kagoshima Prefectural government as a natural monument and by the Act on Conservation of Endangered Species of Wild Fauna and Flora, and listed on the by Appendix III of CITES. Urgent reappraisal of conservational status of this new species is required.

Figures

FIGURE 1. Map of the Central Ryukyus (Amami and Okinawa islands) to show distributional range (shown in black) of Echinotriton in Japan.

FIGURE 3. A: Alive individual (KUHE 49873) of Echinotriton raffaellii, an adult female from Tokunoshima-cho, Oshimagun, Kagoshima Prefecture, B: Dorsal (left) and ventral (right) views of another individual (KUHE 49868) of E. raffaellii, an adult male from Amagi-cho, Oshima-gun, Kagoshima Prefecture. A scale shows 10 mm, C: Full-grown larva of E. raffaellii from unknown locality in Tokunoshima Island, Kagoshima Prefecture (in captivity), D: Alive individual (no voucher specimen) of E. andersoni, an adult female from Okinawajima Island, E: Dorsal (left) and ventral (right) views of holotype (BMNH 1946.9.5.89) of E. andersoni, an adult female from Okinawajima Island. A scale shows 10 mm.

FIGURE 4. Eggs (A) and breeding habitat (B) of Echinotriton raffaellii from Tokunoshima, Kagoshima Prefecture.