Acteonidae, Bullinidae and Ringiculidae (Gastropoda: Heterobranchia) from the Plio-Pleistocene of the Philippines Author Helwerda, Renate A. text Zootaxa 2015 3990 2 197 220 journal article 10.11646/zootaxa.3990.2.2 1740ec81-c55e-44ce-9a6d-cd62acd5d898 1175-5326 242947 BDF1BC11-4848-4858-99DC-0336A5FBEE2B Acteon spec 5 aff. Japonacteon longissimus Valdés, 2008 ( Figure 13 ) Aff. 2008 Japonacteon longissimus n. sp. —Valdés: p. 604–605, figs. 6E–G, 7, 8B. Material. Anda4 (1) RGM 961.743. Characterization. Shell small, juvenile; H 1.29 mm , W 0.99 mm; protoconch slightly elevated, large, 1.3 whorl, DP 0.79 mm ; nucleus small, DN 0.24 mm ; teleoconch 0.8 whorl; teleoconch whorls sculpted with punctuated spiral grooves, becoming stronger towards base; strong groove near suture; interspaces large, becoming smaller towards base; suture weakly channeled with weak punctuated spiral groove; aperture narrow; columella with weak single fold; umbilicus very narrow. Remarks. Only one juvenile specimen with the sculptural details described above, is available. It is similar to the paratype of Japonacteon longissimus Valdés, 2008 from the Philippines , as shown in figure 6F in Valdés (2008) , but this species has two strong punctuated spiral grooves near the suture which grow much wider within the first teleoconch whorl than they do in the specimen RGM 961.743. All other species within Acteonidae , of which material is well described and illustrated, differ from the specimen discussed here in their sculptural details. Yet, many species do not have their protoconch and first teleoconch described, because it is often not preserved on larger shells and juvenile specimens are often overlooked.