Shimada, D.; Kakui, K.; Fujita, Y. (2023). A new species of free-living marine nematode, Fotolaimus cavus sp. nov. (Nematoda, Oncholaimida, Oncholaimidae), isolated from a submarine anchialine cave in the Ryukyu Islands, southwestern Japan. Zoosystematics and Evolution. 99(2): 519-533.
A new species of free-living marine nematode, Fotolaimus cavus sp. nov. (Nematoda, Oncholaimida, Oncholaimidae), isolated from a submarine anchialine cave in the Ryukyu Islands, southwestern Japan
Fotolaimus cavus sp. nov. was described from a submarine anchialine cave called Akuma-no-yakata on the Shimoji Island, Miyako
Island Group, Ryukyu Islands, southwestern Japan. This is the first free-living marine nematode isolated from a submarine cave
in Japan, and the third species of the genus Fotolaimus. This new species differs from its congeners by its small body size, wide
amphids, long buccal cavity, long conico-cylindrical tail, and proximally curved gubernaculum. We provide amended dichotomous
keys to genera in the subfamily Oncholaiminae and species in Fotolaimus. We also analyzed partial DNA sequences encoding ribo-
somal small subunit RNA and cytochrome c oxidase subunit I from Fotolaimus cavus sp. nov. and six other species of Oncholaim-
idae collected from Japanese waters. The phylogenetic tree based on the ribosomal small subunit RNA sequences using maximum
likelihood analysis suggested a close relationship between Fotolaimus and Wiesoncholaimus as well as Oncholaimus. The topology
of the tree was similar to those from previous studies; however, it suggested a new phylogenetic position of Adoncholaimus as a
sister clade for Viscosia and Oncholaimus.