Siphonaria rucuana Pilsbry, 1904

Kim, Yukyung, Park, Jina, Hwang, Ui Wook & Park, Joong-Ki, 2025, Taxonomic review of Korean Siphonaria species (Mollusca, Gastropoda, Siphonariidae), Biodiversity Data Journal 13, pp. e 139388-e 139388 : e139388-

Siphonaria rucuana Pilsbry, 1904

Siphonaria rucuana : Kwon et al. 1993: 335, fig. 61-5.

Siphonaria (Siphonaria) rucuana : Kwon 2001: 191, fig. 722; Lee and Min 2002: 146 [checklist]; Min et al. 2004: 335, fig. 1055; Noseworthy et al. 2007: 90 [checklist].

Distribution

Japan (Okinawa Island).

Type locality: Japan; Ryukyu island (Okinawa Island).

Taxon discussion

Kwon et al. (1993) first reported this species in Korea, based on shell morphology, describing it as having a flatly convex shell with a brown apex curving posteriorly and brown intervals with secondary ribs. However, in contrast to this description, Pilsbry (1904) described S. rucuana as having a steeply conic shell with a glossy brown-coloured apex curving posteriorly and dusky-coloured intervals without secondary ribs. These characteristics are consistent with the recent revision of Jenkins and Köhler (2024). Yokogawa et al. (2010) divided S. japonica into two shell forms — “ tall form ” and “ short form ” — based on an integrative analysis of their morphology, habitat ecology and allelic frequencies. Compared to these two shell forms of S. japonica , the specimens previously described as S. rucuana in Korean waters ( Kwon et al. 1993, Kwon 2001, Min et al. 2004) do not accord with the Pilsbry (1904) ' s original description and morphological characters described in the recent revisional study ( Jenkins and Köhler 2024). A re-evaluation of prior records of S. rucuana in Korea suggests that the specimens described in Kwon et al. (1993) correspond to the “ tall form ” of S. japonica , representing the original S. japonica . On the other hand, the other two reports ( Kwon 2001, Min et al. 2004) are assumed to correspond to the “ short form ” of S. japonica discovered first by Yokogawa et al. (2010) in Japan. In addition to these morphological aspects, S. rucuana is known to have a limited geographic distribution, being reported exclusively from Okinawa Island, a subtropical region of Japan ( Pilsbry 1904, Oyama et al. 1954, Okutani 2000, Okutani 2017). Given this restricted geographic distribution range and the morphological discrepancies observed in the Korean nominal records of “ S. rucuana ”, it is likely that these previous records in the Korean malacofauna result from misidentifications.