Onoba semicostata

Onoba semicostata (Montagu, 1803) (Fig. 8E 1-E 3) Turbo semicostatus Montagu, 1803: 326, pl. 21, fig. 5. Rissoa striata – Wood 1848: 100, pl. 11, fig. 1. Onoba striata – Harmer 1920: 641, pl. 51, fig. 42. Cingula (Cingula) semicostata semicostata – Van Regteren Altena et al. 1954: 12, pl. 4, fig. 35b. — A.W. Janssen 1967: 128, pl. 4, fig. 7. Onoba semicostata – Marquet 1997: 16, pl. 3, fig. 5. — Wienrich 2001: 408, pl. 66, fig. 9. — Raad et al. 2013: 52, fig. 19. — Símonarson & Eiríksson in Eiriksson & Símonarson 2021: 264, pl. 7.3, fig. 5. MATERIAL AND DIMENSIONS. — Maximum height 1.9 mm, width 0.8 mm. — RGM.1364989 (27), leg. ACJ; RGM.1365197 (1), leg. ACJ; RGM.1365095 (800+), leg. AWJ. SPECIES CHARACTERISATION. — Shell small, rissoiform. Smooth protoconch of 1.5 whorl; five round teleoconch whorls separated by deep suture. Adult sculpture consist of axial ribs marked on the upper whorls and numerous fine crowded spiral cords covering the entire whorl. Ovate aperture; rounded, thickened outer lip. DISTRIBUTION. — Middle Miocene: NSB, Germany (Janssen 1967; Wienrich 2001). — Lower Pliocene: Coralline Crag, England (Wood 1848; Harmer 1920) and Belgium (Marquet 1997). — Upper Pliocene: NSB, Belgium (Marquet 1997). — Pliocene to Lower Pleistocene: Iceland (Eiriksson & Símonarson 2021). — Lower Pleistocene: Atlantic, England (Harmer 1920; Norton 1967); Selsoif, NW France (this paper).— Pliocene and Pleistocene (indeterminate):NSB, Netherlands (Van Regteren Altena et al. 1954; Raad et al. 2013). — Holocene: NSB (Strand Petersen 2004). Today this species is present in the Atlantic from Iceland (Warén 1996), Norway (HØisaeter 2009), Kola Peninsula, Russia (Golikov & Kussakin 1978; Nekhaev et al. 2014), British Isles (Fretter & Graham 1978), Madeira (Ávila et al. 2012), southwards to the Alboran Sea in the Mediterranean (Templado & Rolán 1986). Shells collected in the central Mediterranean are probably Late Pleistocene glacial fossils (Amati & Nofroni 2015). Abundant under rocks and among algae, from the intertidal to 1000 m depth. REMARK Onoba semicostata (Montagu, 1803) is primarily a cooler water species that occurs today in the Mediterranean in the Alboran Sea in upwelling zones.