Abstract
Caligoplagusia okinawa n. gen. & n. sp., assigned to the brachyuran family Plagusiidae Dana, 1851 is described on the basis of a male and a female specimens collected from a semi-submerged marine cave on the limestone shore of Okinawa Island, Ryukyu Islands, southwestern Japan. The new monotypic genus is most similar to Euchirograpsus H. Milne Edwards, 1853 and Miersiograpsus Türkay, 1978 in that the frontal margin lacks a deep sublateral cleft adjacent to the orbit, but differs significantly by its subhexagonal carapace shape, the anterolateral margin of the carapace with three teeth including the external orbital tooth, the anterior margin of ambulatory meri each armed with a row of large teeth, and the greatly reduced eyes. The pale body colour, reduced eyes, the very elongate antennal flagellum, and long ambulatory legs are all typical brachyuran adaptations to living in cave environments. This is the first cave-dwelling species of the family Plagusiidae.
References
- Ahyong, S. (2008) Deepwater crabs from seamounts and chemosynthetic habitats off eastern New Zealand (Crustacea: Decapoda: Brachyura). Zootaxa, 1708 (1), 1–72. https://doi.org/10.11646/zootaxa.1708.1.1
- Alves-Juìnior, F.A. de, Santana, J.L. de, Araújo, M.S.L.C. de & Souza-Filho, J.F. de (2016) First record of Euchirograpsus americanus A. Milne-Edwards, 1880 (Crustacea: Decapoda: Plagusiidae) from northeastern Brazil. Nauplius, 24, e2016023. https://doi.org/10.1590/2358-2936e2016023
- Crosnier, A. (2001) Grapsidae (Crustacea, Decapoda, Brachyura) d’eau profonde du Pacifique sud-ouest. Zoosystema, 23, 783–796.
- Dana, J.D. (1851) On the classification of the Crustacea Grapsoidea. American Journal of Science and Arts, Series 2, 12, 283–290.
- Davie, P.J.F. (2021) Crabs: A Global Natural History. Princeton University Press, Princeton, 190 pp. https://doi.org/10.1515/9780691230139
- Fujita, Y. (2018) Current situation of decapod crustacean research in marine and anchialine caves of the Ryukyu Islands. TAXA (Proceedings of the Japanese Society of Systematic Zoology), 44, 15–22. [in Japanese with English abstract]
- Fujita, Y. (2019) The fauna of decapod crustaceans in submarine caves of the Ryukyu Islands, with special reference to environmental factors in the caves. TAXA (Proceedings of the Japanese Society of Systematic Zoology), 46, 3–12. [in Japanese with English abstract]
- Fujita, Y. & Naruse, T. (2011) Catoptrus iejima, a new species of cavernicolous swimming crab (Crustacea: Brachyura: Portunidae) from a submarine cave at Ie Island, Ryukyu Islands, Japan. Zootaxa, 2918 (1), 29–38. https://doi.org/10.11646/zootaxa.2918.1.3
- Guinot, D. (2007) A new genus of the family Plagusiidae Dana, 1851, close to Plagusia Latreille, 1804 (Crustacea, Decapoda, Brachyura). Zootaxa, 1498 (1), 27–33. https://doi.org/10.11646/zootaxa.1498.1.2
- Holthuis, L.B. (1986) Decapoda. In: Botosaneanu, L. (Ed.), Stygofauna Mundi. A faunistic, Distributional, and Ecological Synthesis of the World Fauna Inhabiting Subterranean Waters (Including the Marine Interstitial), E. J. Brill, Leiden, pp. 589–615. https://doi.org/10.1163/9789004631977_071
- Komai, T. & Fujita, Y. (2005) A new stygiobiont species of Macrobrachium (Crustacea: Decapoda: Caridea: Palaemonidae) from an anchialine cave on Miyako Island, Ryukyu Islands. Zootaxa, 1021, 13−27. https://doi.org/10.11646/zootaxa.1021.1.2
- Komai, T. & Fujita, Y. (2018) A new genus and new species of alpheid shrimp from a marine cave in the Ryukyu Islands, Japan, with additional record of Salmoneus antricola Komai, Yamada & Yunokawa, 2015 (Crustacea: Decapoda: Caridea). Zootaxa, 4369 (4), 575−586. https://doi.org/10.11646/zootaxa.4369.4.7
- Latreille, P.A. (1804) Crustaceìs (1). Crustacea. Classe SeptieÌme. Tableau meìthodique des Crustaceìs. Nouveau Dictionnaire d’Histoire Naturelle, 24, 123−127.
- Macpherson, E. (1988) New records of decapods crustaceans from the coast off Namibia/south west Africa, with the descriptions of two new species. Investigación Pesquera, 52, 51−66.
- Milne Edwards, H. (1853) Meìmoire sur la famille des Ocypodiens. Annales de Sciences naturelles, Series 3, 20, 163−226.
- Naruse, T. & Fujita, Y. (2015) Lipkemera iejima, a new cavernicolous crab (Brachyura: Xanthidae) from a submarine cave at Ie Island, central Ryukyu Islands, Japan. Crustacean Research, 44, 21−27. https://doi.org/10.18353/crustacea.44.0_21
- Ng, N.K. & Martin, J.W. (2010) Two new species of grapsoid crabs of the genus Euchirograpsus (Decapoda, Brachyura, Grapsoidea, Plagusiidae) from the Philippines and the Hawaiian Islands. In: Castro, P., Davie, P.J.F., Ng, P.K.L. & Richer de Forges, B. (Eds.), Studies on Brachyura: a Homage to DanieÌle Guinot. Crustaceana Monographs, 11, 229–249. https://doi.org/10.1163/ej.9789004170865.i-366.143
- Ng, N.K. & Ng, P.K.L. (2022) The identity of Euchirograpsus polyodous (Stebbing, 1921) (Decapoda, Brachyura, Plagusiidae), with a key to the genus. Crustaceana, 95, 385–403. https://doi.org/10.1163/15685403-bja10189
- Osawa, M. & Fujita, Y. (2022) A new species of the genus Eutrichopagurus Komai, 2015 (Crustacea: Decapoda: Anomura: Paguridae) from a submarine cave in the Ryukyu Islands, southwestern Japan. Zootaxa, 5214 (3), 440−450. https://doi.org/10.11646/zootaxa.5214.3.6
- Promdam, R., Ellis, M. & Jantarit, S. (2022) Brachyuran crabs (Crustacea: Decapoda) in the limestone caves of Thailand, with a checklist of freshwater cave-dwelling crabs in Southeast Asia. Edaphologia, 110, 1–17. https://doi.org/10.20695/edaphologia.110.0_1
- Saito, T. & Fujita, Y. (2018) A new species of the stenopodidean shrimp genus Odontozona Holthuis, 1946 (Crustacea: Decapoda: Stenopodidea: Stenopodidae) from the Ryukyu Islands, Indo-West Pacific. Zootaxa, 4450 (4), 458−472. https://doi.org/10.11646/zootaxa.4450.4.4
- Saito, T. & Fujita, Y. (2022) A new stenopodid shrimp of the genus Odontozona Holthuis, 1946 (Crustacea: Decapoda: Stenopodidea) from the submarine cave of the Ryukyu Islands, Indo-West Pacific. Zootaxa, 5175, 439−452. https://doi.org/10.11646/zootaxa.5175.4.2
- Schubart, C.D. & Cuesta, J.A. (2010) Phylogenetic relationships of the Plagusiidae Dana, 1851 (Brachyura), with description of a new genus and recognition of Percnidae Stevcic, 2005, as an independent family. In: Castro, P., Davie, P.J.F., Ng, P.K.L. & Richer de Forges, B. (Eds.), Studies on Brachyura: a Homage to DanieÌle Guinot. Crustaceana Monographs, 11, 279−300. https://doi.org/10.1163/ej.9789004170865.i-366.171
- Schubart, C.D., Cuesta, J.A., Diesel, R. & Felder, D.L. (2000) Molecular phylogeny, taxonomy, and evolution of nonmarine lineages within the American grapsoid crabs (Crustacea: Brachyura). Molecular Phylogenetics and Evolution, 15 (2), 179–190. https://doi.org/10.1006/mpev.1999.0754
- Števčić, Z. (2005) The reclassification of brachyuran crabs (Crustacea, Decapoda: Brachyura). Natura Croatica, 14 (Supplement 1), 1−159.
- Tsang, C.T.T., Schubart, C.D, Chu, K.H., Ng, P.K.L. & Tsang, L.M. (2022) Molecular phylogeny of Thoracotremata crabs (Decapoda, Brachyura): Toward adopting monophyletic superfamilies, invasion history into terrestrial habitats and multiple origins of symbiosis. Molecular Phylogenetics and Evolution, 177, 107596. https://doi.org/10.1016/j.ympev.2022.107596
- Türkay, M. (1975) Zur Kenntnis der Gatung Euchirograpsus mit Bemerkungen zu Brachygrapsus und Litocheira (Crustacea, Decapoda). Senckenbergiana biologica, 56, 103–132.
- Türkay, M. (1978) Zwei neue Grapsiden-Arten aus dem Indopaziik, (Euchirograpsus madagascariensis n. sp. und Miersiograpsus australiensis n. sp.) mit Einführung von Miersiograpsus n. gen. (Crustacea: Decapoda: Grapsidae). Senckenbergiana biologica, 59, 133–141.