Plexechinus hirsutus Mortensen 1905

Plexechinus hirsutus Mortensen, 1905. AphialD: 124351. New record. (Fig. 3 a–b). Material examined. 64 preserved specimens with catalogue numbers (stations included): 124351-B150 (B11 V 02); 124351-B151 (B11 V 05); 124351-B152 (B11 V 05); 124351-B153 (B11 V 05); 124351-B154 (B11 V 02). Description. Labrum and sternum disjunct, apical disc with fused genital plates 2 and 3, petals absent, single pore per ambulacral plate, and subanal fasciole present (Fig. 3a, b). Test oval in outline and rounded anteriorly in aboral view, presence of a small hood above anal rostrum on the posterior margin (Fig. 3a, b). Anterior ambulacrum sunken adorally (Fig. 3a). Plastron (sternum) keeled (Fig. 3b). Apical system disjunct with only two gonopores on fused anterior genital plates 2 and 4, gonopores absent on posterior genitals (Fig. 3a). Distribution. Atlantic Ocean: Bay of Biscay, west and south of Iceland, Caribbean Sea (Santa Lucía, San Vicente y las Granadinas) (Mortensen, 1905; Mortensen 1927; Schultz, 2009; Kroh, & Mooi, 2022; OBIS, 2022) Bathymetric range. 658–2375 m (Schultz 2009). Present study: 1631–1706 m. Remarks. To date seven species of the genus Plexechinus A. Agassiz, 1898 have been described worldwide. Only P. hirsutus is known in the study area and cannot be mistaken for any other known co-occurring species.