The laboratory of Professor Ko Tomikawa at the Graduate School of Humanities and Social Sciences of Hiroshima University and that of Associate Professor Takafumi Nakano at the Graduate School of Science of Kyoto University jointly conducted morphological and DNA-based analyses of a new pseudocrangonyctid amphipod species (shrimp-like crustaceans) collected at a quarry on Mt. Asuwa "Nanatsuo-guchi" (Fukui City, Fukui Prefecture) in November 2017 and classified it as Asuwamekurayokoebi, Pseudocrangonyx asuwaensis. The details were published in Zootaxa.
So far, 41 species of the genus Pseudocrangonyx have been found in groundwater. The genus is mainly distributed in East Asia, Japan, the Korean peninsula, China, and Far Eastern Russia. Ten species have been found in Japan. P. asuwaensis, discovered by Mr. Shinya Umemura (Curator of the Fukui City Museum of Natural History) and Mr. Yasunobu Yoshizawa (former Special Director of the Fukui City Museum of Natural History) is the 42nd species in the world and 11th species in Japan belonging to the genus Pseudocrangonyx. It has a body length is 4−8.9 mm.
The length of the antennae, morphology of the base of the antennae and tail, number of hairs on the mouthparts and length of the segments that make them up are different from those of closely related species.
Since November 2017, the Fukui City Museum of Natural History has been monitoring the ecology of this species in the quarry, observing egg-bearing individuals in August 2021 and April 2022, and preserving video documentation of them. This is a very valuable record for elucidating breeding ecology.
In addition to the Nanatsuo-guchi quarry specimens, some Pseudocrangonyx individuals have been found on Mt. Asuwa, and these will be analyzed by Tomikawa. Observations in the quarry will be continued to accumulate knowledge about their feeding habits and breeding season. Additionally, because the artificial incubation of eggs collected from egg-bearing individuals has not been successful, knowledge of their ecology will be accumulated through a combination of indoor rearing and observation. P. asuwaensis is thought to be found in other locations in Fukui Prefecture.
The Fukui City Museum of Natural History will search for Pseudocrangonyx individuals in Fukui Prefecture, mainly around Mt. Asuwa, and once found, they will ask Tomikawa to analyze their relationship to P. asuwaensis.
Title: A new species of the genus Pseudocrangonyx (Crustacea: Amphipoda: Pseudocrangonyctidae) from subterranean waters of Japan
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