Seguenzia Jeffreys, 1876

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 : 64

Seguenzia Jeffreys, 1876

( Figure 2 )

Seguenzia Jeffreys, 1876: 200 . Type species (M): S. formosa Jeffreys, 1876 . Northwest Atlantic.

Description. Shell to 10 mm, thin, fragile, umbilicate or anomphalous, external and internal surfaces with nacreous luster. Apertural lip bordering three labral sinuses often flaring in mature shells. Columella curved, ending abruptly. Sculpture of narrow spiral carinae, basal cords; fine spiral threads, sharp axial riblets curving parallel to labral sinuses.

Remarks. Species occur throughout the world on the lower continental slope and abyssal plain. Seguenzia occidentalis Dall, 1908 (see Keen 1971) is known from the Panamic Province. There are two groups of Seguenzia , 1) specimens with globular shells and with less prominent spiral keels: S. cervola , S. macleani , and 2) biconical shells with more prominent spiral keels: S. giovia , S. stephanica .

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.