A joint research group led by Division Head Tomoyuki Komai of the Zoology Division at the Natural History Museum and Institute, Chiba, and Assistant Professor Yumi Henmi of the Field Science Education and Research Center at Kyoto University, discovered an undescribed crustacean from the seafloor of Wakasa Bay and Sagami Bay. The research group described it as a new species of the genus Athanas, "Athanas acudactylus (Japanese name: aka-murasakiebi)." The new species was named by combining the Latin words "acus," meaning "needle," and "dactylus," meaning "finger," because the third to fifth pereopod dactyli are particularly elongated. The Japanese name is derived from its bright red live body coloration, which is distinct from other species of the genus Athanas. Moreover, they found male specimens of Athanas exilis (Japanese name: wakasa-murasakiebi), which had been described in 2023 as a new species based on a single female specimen and provided a detailed description of its characteristics. Male characteristics of Athanas exilis included large, leaf-like chelipeds, which are distinct from those of females, revealing the presence of remarkable sexual dimorphism. The study was published online in Zootaxa.
The genus Athanas of the family Alpheidae, belonging to the infraorder Caridea of the order Decapoda, is characterized by high species diversity. This genus also has high ecological diversity, including free-living species and species that live symbiotically with other organisms. As a result of the description of A. acudactylus as a new species here, the genus now includes 44 species worldwide and 14 species in the Japanese coastal waters and is being reevaluated in light of high species diversity. Moreover, the remarkable sexual dimorphism in A. exilis noted in this study may be related to reproductive behavior and ecological roles, and further research in the field of ecology and taxonomy is awaited. In particular, there is a high expectation for unveiling how the peculiar fan-like chelipeds are used.
Komai said, "This is a species of the genus Athanas, but it can also be found in tidal flats and rocky shores. It is small and easy to miss, but there will be new discoveries still to be made."
Henmi said, "We will continue to keep a close eye on the shrimp in Wakasa Bay to find out how the large pincers of male Athanas exilis shrimp are used, and what are the morphological characteristics of Athanas acudactylus males."
Journal Information
Publication: Zootaxa
Title: A new species of the alpheid shrimp genus Athanas Leach, 1814 (Decapoda: Caridea) from Japan, and additional record of Athanas exilis Komai & Henmi, 2023, clarifying male characteristics
DOI: 10.11646/ZOOTAXA.5583.2.7
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