Rhabdoploca curvispiculifera var. geniculatus (Topsent, 1928)

(Fig. 5D)

Hymeraphia geniculata Topsent, 1892: 115, pl. I fig. 13, pl. XI fig. 4–5.

Hymerhabdia curvispiculifera; sensu Topsent 1894: 22.

Rhabderemia geniculata; Topsent 1894: 23.

Rhabdoploca curvispiculifera; sensu Topsent 1904: 158.

Rhabdoploca curvispiculifera var. geniculata; Topsent 1928: 43.

Cerbaris curvispiculifer; sensu Alvarez & Van Soest 2002: 751.

The variety was originally described by Topsent as Hymeraphia geniculata from the Azores, Prince Albert 1 er Cruises Stat. 247, 38.3917°N 30.3389°W, 318 m depth (holotype in MOM, a slide of the type in MNHN reg. nr. DT 944). Topsent changed his mind several times and decided ultimately to reassign H. geniculata to Rhabdoploca curvispiculifera (Carter, 1880: 43 as Microciona, from the Gulf of Mannar, Sri Lanka, approximate coordinates 9°N 79°E, type not identified) as a distinct Atlantic variety. Alvarez & Van Soest (2002) transferred Carter’s (1880) Rhabdoploca curvispiculifera to Cerbaris Topsent, 1898, and by this implicitly transferred the var. geniculata also to that genus. A difference between Carter’s curvispiculifer and Topsent’s geniculatus is found in the small tylostyles, which are entirely smooth in Carter’s typical variety and entirely spined in Topsent’s variety. Other skeletal characters of the two are strikingly similar: the length of the (rhabdo)styles, in Carter’s species 207 x 13, and Topsent’s species 90–200 x 10–12 µm. The ‘toxostrongyles’ of both species are on average approximately the same (207 x 9 µm vs 125–195 x 6–8 µm, respectively). I agree with Topsent (1928) that geniculatus has a small but distinct difference, and to acknowledge the geographic separation I propose here to elevate the variety to the rank of species as Cerbaris geniculatus (Topsent, 1892) .