Okamiya Hisanori, Sugime Ryohei, Furusawa Chiharu, Inoue Yoshihiro, Kishida Osamu
Field Science Center for Northern Biosphere, Hokkaido University, Takaoka, Tomakomai, Japan.
Graduate School of Environmental Science, Hokkaido University, Takaoka, Tomakomai, Japan.
Zoological Lett. 2021 Dec 8;7(1):14. doi: 10.1186/s40851-021-00183-x.
Although paedomorphosis is widespread across salamander families, only two species have ever been documented to exhibit paedomorphosis in Hynobiidae. One of these two exceptional species is Hynobius retardatus in which paedomorphosis was first reported in 1924, in specimens from Lake Kuttara in Hokkaido. This population became extinct after the last observation in 1932; since then, no paedomorphs of this species have been reported anywhere. Here, we report the rediscovery of paedomorphs of this species. Three paedomorph-like male salamanders were collected from a pond in the south Hokkaido in December 2020 and April 2021; in size, these specimens were similar to metamorphosed adults but they still displayed larval features such as external gills and a well-developed caudal fin. An artificial fertilization experiment demonstrated that they were sexually compatible with metamorphosed females, thus, confirming them to be paedomorphs. Future efforts to find additional paedomorphs in this and other populations are required to assess the prevalence of paedomorphosis in H. retardatus and to improve understanding of the ecology and evolution of paedomorphisis in Urodela.
虽然幼态延续现象在蝾螈科中普遍存在，但在隐鳃鲵科中，仅有两个物种被记录有幼态延续现象。这两个特殊物种之一是极北小鲵，1924年在北海道库塔拉湖的标本中首次报道了其幼态延续现象。该种群在1932年最后一次观察后灭绝；从那时起，在任何地方都没有再报道过该物种的幼态个体。在此，我们报告该物种幼态个体的重新发现。2020年12月和2021年4月，在北海道南部的一个池塘中采集到了三只类似幼态个体的雄性蝾螈；这些标本在大小上与变态后的成体相似，但仍表现出幼体特征，如外鳃和发育良好的尾鳍。人工授精实验表明，它们与变态后的雌性能进行有性繁殖，因此，确认它们为幼态个体。未来需要进一步努力在该种群及其他种群中寻找更多的幼态个体，以评估极北小鲵幼态延续现象的普遍性，并增进对有尾目动物幼态延续现象的生态和进化的理解。
