Seguenzia stephanica Dall, 1908

Geiger, Daniel L., 2019, The Family Seguenziidae Verrill, 1884 in the Northeast Pacific, including a comment on excessive numbers of taxonomic data portals, Zoosymposia 13, pp. 61-69 : 66

Seguenzia stephanica Dall, 1908

( Figure 2 G–H)

Seguenzia stephanica Dall, 1908: 325 . Holotype USNM 123034. Ventana Bay , Baja California, 1820 m.

Seguenzia caliana Dall, 1919: 344 . Holotype USNM 207674 . Off San Diego, California, 417 fms [= 762 m]. New synonym.

Seguenzia certoma Dall, 1919: 343 . Holotype USNM 211167. Off Point Loma, San Diego, California, 565–680 fms [= 1033– 1243 m]. New synonym.

Description. Shell to 8 mm, globular biconical; carinated spiral cords below suture, strongest one mid shoulder, approximately 8–15 from periphery to umbilicus, count increasing with size; intercalated spiral lines at best faint; axial cordlets distinct. Umbilicus very narrow in small specimens, closed by callus in larger shells. Columellar wall thickened, terminating in sharp spur. Flaring of lip variable depending on size, preservation of specimen.

Distribution. Aleutian Islands, Alaska (175°E) to Peru (3° S). 750–5100 m.

Remarks. Smaller specimens have proportionally more pronounced spiral and axial sculpture. The types of the three nominate taxa represent growth stages of the same species.

Figures

FIGURE 2. A–B. Seguenzia cervola Dall, 1919. A. 1130–1266 m, off North Coronado Island, Baja California (USNM 209229, holotype), 4.5 mm. B. 3592–3798 m, SW of Farallon Islands and W of Pioneer Seamount, off San Francisco County, California (USNM 701260, holotype of S. megaloconcha), 9.2 mm. C–D. Seguenzia macleani Geiger, 2017. C. 5100 m, Aleutian Trench at 175° 44' E (LACM 3321), holotype, 8.7 mm. D. 5180 m, abyssal plain W of Oregon, S of Gulf of Alaska (approximately 45° N, 153.8° W) (LACM 3486, paratype), 9.6 mm. E–F. Seguenzia giovia Dall, 1919. E. 874–1097 m, off Santa Catalina Island, Los Angeles County, California (USNM 209228, holotype), 6 mm. F. 3900 m, Tufts Abyssal Plain, W of Lincoln County, Oregon (LACM 2065, holotype of S. quinni), 7.6 mm. G–H. Seguenzia stephanica Dall, 1908. G. 2816 m, Cascadia Abyssal Plain, off Oregon (LACM 70-140.5), 7.1 mm. H. 5100 m, Aleutian Trench, Alaska at 44° N, 175° E (LACM), 5.2 mm.