Tetrarca boucardi

Tetrarca boucardi (Jousseaume, 1894) (Fig. 2 Q, R) Arca boucardi Jousseaume, 1894: 41. Tetrarca boucardi (Jousseaume, 1894) — Vermeij & Amano 2021: 44. Material examined: eight specimens from the sea slope of the southern Kuril Islands (Iturup and Kunashir Islands) and the Shpanberg Strait (5–55 m). Distribution: Yellow Sea; Taiwan; Okinawa, Kyushu to Hokkaido; Sea of Japan; south Kuril Islands, Shpanberg Strait (0–68 m) (Scarlato 1981; Darkina & Lutaenko 1996; Evseev 2000; Matsukuma & Okutani 2000, 2017; Kantor & Sysoev 2005; Lutaenko & Maestrati 2007; Liu 2008; Nobetsu & Yamazaki 2011; Lutaenko & Noseworthy 2012; Lee 2013). Remarks: Previously, this warm-water species was recorded only from off Kunashir Island (Evseev 2000). New findings of Tetrarca boucardi (Jousseaume, 1894) have extended the range of this species northward along the Kuril Islands to Iturup. Lutaenko & Maestrati (2007) indicated that T. boucardi was found at depths to 175 m, but it is not completely clear whether those findings were live-collected individuals or empty shells.