The second rhizocephalan species, Lernaeodiscus kasyanovi sp. nov. (Cirripedia: Rhizocephala: Peltogastridae), parasitizing the porcellanid crab Pachycheles stevensii Stimpson, 1858 (Decapoda: Anomura: Porcellanidae), from Russian waters of the Sea of Japan

Molecular and morphological methods are used to describe the rhizocephalan Lernaeodiscus kasyanovi sp. nov. from Russian waters of the Sea of Japan, the second of two Lernaeodiscus species parasitizing the porcellanid crab Pachycheles stevensii Stimpson, 1858. Lernaeodiscus kasyanovi sp. nov. differs from the other species found on this host, Lernaeodiscus rybakovi Korn et al., 2020a, by molecular markers, by a smaller size, a lighter color, by the shape of receptacles, by the presence of marginal lobes in mature specimens, and by the retinacula type on the internal cuticle. Lernaeodiscus kasyanovi sp. nov. is the sister taxon to Lernaeodiscus porcellanae in the monophyletic genus Lernaeodiscus. Lernaeodiscus kasyanovi is rather rare compared to L. rybakovi, their prevalence on the porcellanid crab P. stevensii does not exceed 2%. It is the second example of two rhizocephalan species infesting the same brachyuran species in Peter the Great Bay.

Automated summary

A new rhizocephalan species, Lernaeodiscus kasyanovi, was described from Russian waters of the Sea of Japan, differing from another species found on the same host by molecular markers and morphological characteristics. It is the second known example of two rhizocephalan species infesting the same brachyuran species in Peter the Great Bay, with a prevalence not exceeding 2%.