Japonacteon sieboldii (Reeve, 1842) (Figure 1–3) 1842 Tornatella siebaldii n. sp. —Reeve: p. 61. 2000 Acteon siebaldi (Reeve, 1842) —Hori: p. 733, pl. 365, fig. 1. 2008 Japonacteon sieboldii (Reeve, 1842) —Valdés: p. 601–604, figs. 6A–D, 7, 8A. Material. Anda1 (2) RGM 961.760, Anda2 (fragments) RGM 961.761, Anda3 (2) RGM 961.762, Anda4 (5) RGM 961.763, AndaDeVos (2) RGM 961.764, Roxas (2) RGM 961.765, Tiep2 (1) RGM 961.766, Tiep5 (1) RGM 961.767. Characterization. Shell tall; H 5.95 mm, W 2.90 mm; protoconch inclined, 1.1 whorl, DP 0.51–0.54 mm; nucleus small, DN 0.21 mm; teleoconch sculpted with punctuated spiral grooves with oval punctuations; strong spiral groove with elongated punctuations below suture; space between grooves increases along the whorl, additional grooves intercalate; aperture narrowly semicircular; columella with weak single fold; umbilicus very narrow to closed. Distribution. Japan and South China Sea, sand bottom, in 10–30 m (Hori, 2000). Fiji, Indonesia, New Caledonia, Tonga, Vanuatu and Wallis Island, in 182–555 m, live in 440–487 m (Valdés, 2008). Remarks. According to Valdés (2008), this species might represent a species complex, because of its variability in shell morphology and broad geographic and bathymetric range. Valdés (2008) further mentions that all specimens share a closed umbilicus, yet we also encountered specimens with a very narrowly open or rimate umbilicus.

Published as part of Helwerda, Renate A., 2015, Acteonidae, Bullinidae and Ringiculidae (Gastropoda: Heterobranchia) from the Plio-Pleistocene of the Philippines, pp. 197-220 in Zootaxa 3990 (2) on pages 198-201, DOI: 10.11646/zootaxa.3990.2.2, http://zenodo.org/record/242947