Preservation and Research Center, City of Yokohama amphibians

<scientific name> Rana japonica
It is endemic to the Japanese Islands and inhabits low mountain forests, paddy fields, grasslands, etc. from plains of Honshu, Shikoku, Kyushu and surrounding islands. In Yokohama city, habitat has been confirmed in Tando in the northern part of the city. It spawns in early spring, and the egg mass is spherical and large onigiri. The body color on the back is reddish-brown or orange rather than red, similar to Montane Brown Frog (Rana ornativentris), but the male of this species can be distinguished by the fact that it does not have a squeal sac (the part that greatly expands when it squeals) or the pattern of the tadpoles. In addition, this species seems to sleep in spring after spawning in early spring. In the past, Tokyo-grown Japanese Brown Frog was regarded as a Martens frog, but now all are treated as Japanese Brown Frog. On the other hand, the East and West Japan groups in Japanese Brown Frog are said to be reproductively isolated, and if future catastrophic research progresses, this species may be divided into multiple species.

<scientific name> Glandirana reliquia
It can be found in various places such as paddy fields and rivers on the Tohoku Pacific side from Kanto, including Yokohama City, and ponds in parks, but it is said to be frogs that rarely leave the water. In Yokohama city, it is rarely seen in rivers in the northern part of the city.
An analysis of the Wrinkled Frog and its morphology and mitochondria DNA, which are widely inhabited in Honshu, Shikoku, and Kyushu, found that the species were separated from those closely related to the continent before the Wrinkled Frog, and that they were transferred to Japan and remained to date. In August 2022, they were registered as Mukashi Wrinkled Frog.
The spawning season is from April to August, and dozens of eggs are laid on aquatic plants. The back is light brown or yellowish and has many warts, and the skin feels rough. It is known to be the only native frogs in Honshu that winter in tadpoles.
In order to prevent the extinction of the Mukashi Wrinkled Frog produced in Yokohama, Preservation and Research Center has been conducting trial reintroduction of the Wrinkled Frog produced in the city since 2021.
※About reintroduction of Mukashi Wrinkled Frog