Hynobius geiyoensis Sugawara, Naito, Iwata, and Nagano, 2022

Tomimori, Yusuke, Matsui, Masafumi, Okawa, Hiroshi, Nishikawa, Kanto, Tanabe, Shingo & Kamasaka, Ryo, 2023, Reassessment of species delimitation using nuclear markers in three lentic-breeding salamanders from the Chugoku District of Japan (Amphibia: Caudata: Hynobiidae), Zootaxa 5293 (1), pp. 145-160 : 153-154

Hynobius geiyoensis Sugawara, Naito, Iwata, and Nagano, 2022

Hynobius nebulosus (part, as Osakijima morphotype) Okawa and Utsunomiya, 1989, 142.

Hynobius nebulosus (part, as Island morphotype) Okawa et al., 1999, 47.

Hynobius nebulosus (part, as Shikoku morphotype) Okawa et al., 2007, 58.

Hynobius akiensis (part) Matsui et al., 2019, 32.

Holotype: HMNH (Hiwa Museum for Natural History) AM-101, from Osakikamijima-cho , Hiroshima Prefecture.

Paratypes: KPM (Kanagawa Prefectural Museum of Natural History ) NFA 943, KPM-NFA 944, from the same locality as the holotype .

Specimens referred in the present paper. Hiroshima Prefecture: Osakikamijima Island , KUHE OU0957- 0961 , from Nakano, collected by H. Okawa on 13 March 2019 . KUHE 62645 , 62660 , 62666–62671 , from Nakano, collected by Y. Tomimori on 17 February 2021 . Ehime Prefecture: Imabari-shi , KUHE OU0343 , 0344 , 0347 , 0348 , from the former Namikata-cho, collected by H. Okawa on 5 April 2008 . KUHE T 2839–2842 , 2844 , 2845 , from the former Namikata-cho, collected by S. Tanabe and K . Okayama on 1 March 1997 . KUHE T 3284 , 3285 , from the former Namikata-cho, collected by S. Tanabe and K . Okayama on 21 March 2005 .

Diagnosis. A medium-sized species (SVL 53.3–67.3 mm in males) of the lentic-breeding Hynobius ; White dots are dense on the lateral and ventral sides, and black dots are visible on the dorsum. Tips of fore- and hindlimbs adpressed on body do not overlap in either male or female (overlap of −2.0 to 0 and -3.5 to -2.5 costal folds, respectively). Head, trunk, and tail clearly longer and the fifth toe more developed than in genetically close relative, H. akiensis and H. sumidai .

Color. Body coloration greatly variable, with dorsum of body ranging from dark to yellowish brown, sometimes with black spots in life. Tail lacking yellowish-brown stripes on dorsal and ventral sides, although seldom with an indistinct stripe on dorsum. Ventral side of body grayish brown scattered with silvery white spots. White nuptial color on throat distinct in males.

Variation. Morphological measurement data for males are summarized in Table 2 . In 16 males examined, SVL 60.4 ±3.7 (53.3–67.3) mm, adpressed limbs always separated, and the fifth toe always present. In addition, all individuals with many fine white spots on ventral side of body, more pronounced in younger individuals .

Range. Known only from two areas on Osaki-kamijima-cho, Toyota-gun, Hiroshima Prefecture and Imabari-shi, Ehime Prefecture ( Fig. 1 ).

Altitude of the localities extending from 9.6– 185.0 m a.s.l. with the mean±SD of 51.1± 37.4 m (n=25).

Natural history. Breeding usually occurs from late January to early March in Hiroshima Prefecture, but from late December to early May in Ehime Prefecture. ( Itano et al. 2016). Egg sacs are string-like in shape and coiling. Number of eggs is 62 ± 13.3 (34–93) ( Tanabe and Okayama 2001). The minimum and maximum water temperatures at the time of breeding were 3.5–6.6°C and 8.0–13.6°C, respectively in Ehime Prefecture. ( Itano et al. 2016).

Morphological Comparisons. Hynobius geiyoensis has a dark brown body color with small white dots, a body color pattern that is often seen in lentic Hynobius (e.g., H. sumidai , H. akiensis , H. setouchi , H. utsunomiyaorum , H. iwami , H. abuensis , H. bakan , H. setoi , and H. kunibiki ). However, H. iwami , H. bakan , H. setoi , and H. kunibiki can be distinguished from H. geiyoensis by distinct yellow stripes on dorsal and ventral sides of tail. Hynobius geiyoensis (mean male SVL 60.4 mm) is distinctly larger than H. sumidai (47.6 mm), H. akiensis (48.8 mm), and H. setouchi (51.5 mm). In addition, this species lacks striations on the envelope of egg sacs unlike H. abuensis . However, it may be confused with H. setouchi , which is known to be distributed in Shikoku and the islands of the Seto Inland Sea. Hynobius geiyoensis is distinguishable from the genetically close H. sumidai by its significantly larger SVL and by shorter head length, wider interorbital, smaller eyes, longer trunk and tail, wider medial tail lower basal tail, longer hindlimb and fifth toe, and narrower vomerine teeth series. Hynobius geiyoensis is distinguishable from H. akiensis by its significantly larger SVL and following ratio values: shorter head length, smaller eyes, longer trunk, tail and fifth toe. Hynobius geiyoensis is distinguishable from H. setouchi by its significantly larger SVL and following ratio values: shorter maximum head width, shorter lower jaw and snout, narrower upper eyelid, longer trunk, lower basal and medial tail, shorter third toe, and smaller vomerine teeth series. Hynobius geiyoensis is distinguishable from H. utsunomiyaorum by its significantly larger SVL and following ratio values: wider interorbital, longer trunk, tail, hindlimb, third finger, third toe, and fifth toe, and larger vomerine teeth series.

Protection. H. geiyoensis is in the Japanese Red List as Endangered (EN) under the name of H. akiensis (Ministry of the Environment Government of Japan 2020) and is listed as Vulnerable (VU) by the Red Data List Ehime ( Tanabe 2014). This species is presently protected by Ehime Prefecture, However , there is currently no effective protection law on Osakikamijima Island in Hiroshima Prefecture. Due to very limited distribution range, conservation status of this species needs to be immediately reassessed.

Figures

FIGURE. 1. Map of Chugoku and Shikoku district showing ranges of Hynobius akiensis, H. sumidai, H. geiyoensis, H. utsunomiyaorum, H. setouchi and H. iwami.