Olivella (Anasser), Absalão & Pimenta, 2003

Absalão, Ricardo S. & Pimenta, Alexandre D., 2003, A new subgenus and three new species of Brazilian deep water Olivella Swainson, 1831 (Mollusca, Gastropoda, Olivellidae) collected by the RV Marion Dufresne in 1987, Zoosystema 25 (2), pp. 177-185 : 180

publication ID	https://doi.org/ 10.5281/zenodo.5757059
persistent identifier	https://treatment.plazi.org/id/0386786B-FFC3-FF8E-C704-FCB4A31BEEEB
treatment provided by	Marcus
scientific name	Olivella (Anasser)
status	subgen. nov.

Treatment

Subgenus Anasser n. subgen.

TYPE SPECIES. — Olivella amblia Watson, 1882 . Recent, off Brazil , southern Atlantic.

ETYMOLOGY. — This taxon is named after its characteristic absence of pillar structure: an (Latin), without; and asser (Latin), pillar.

DESCRIPTION

Small and large Olivella , whitish or very light colors. Parietal callus light to moderately developed, reaching the apertural end but not above it. No pillar structure. Lirae on the inner side of the outer lip absent. Suture channeled. Operculum chitinous, usually present. Internal ressorption of shell.

Olivella (Anasser) amblia Watson, 1882 ( Fig. 1 View FIG A-C)

TYPE MATERIAL. — Three syntypes ( BMNH

1887.2.9.771-3).

TYPE LOCALITY. — Off Pernambuco, Brazil ,

Challenger Expedition, stn 122.

MATERIAL EXAMINED. — The type material photographs and: MD-55, stn CB95, 19°38’S, 38°43’W,

960 m, + 50 spec. ( MNHN) ; MD-55, stn CB93,

19°36’S, 38°53’W, 640 m, 45 spec.; MD-55, stn

CB78, 18°58’8”S, 37°48’4”W, 1200 m, 13 spec.;

MD-55, stn CB95, 19°38’4”S, 38°43’4”W, 960 m,

+ 50 spec.; MD-55, stn DC70, 18°59’1”S, 37°47’8”W, 1540-1550 m, 12 spec.; MD-55, stn CB97, 21°33’9”S, 40°08’4”W, 600 m, 5 spec.; MD- 55, stn CB76, 18°58’9”S, 37°49’6”W, 637 m, 7 spec.; MD-55, stn SY74, 18°58’S, 37°49’W, 682 m, 2 spec.; MD-55, stn CB79, 19°01’8”S, 37°47’8”W, 1500- 1575 m, 3 spec.; MD-55, stn CB105, 23°46’7”S, 42°10’1”W, 610 m, 8 spec.

REMARKS

See under O. (A.) ephamilla Watson, 1882 .

Olivella (Anasser) ephamilla Watson, 1882 ( Fig. 1 View FIG D-F)

TYPE MATERIAL. — Three syntypes ( BMNH

1887.2.9.774).

TYPE LOCALITY. — Off Pernambuco, Brazil ,

Challenger Expedition, stn 122.

MATERIAL EXAMINED. — The type material photographs and: MD-55, stn DC73, 18°59’5”S, 37°48’2” W,

607-620 m, 106 spec. ( MNHN).

REMARKS

Olivella amblia Watson, 1882 ( Fig. 1 View FIG A-C) and O. ephamilla Watson, 1882 ( Fig. 1 View FIG D-F) were described based on three shells each and were known, up to now, by their original descriptions and illustrations only. Examination of the photographs of these syntypes ( Fig. 1A, B, D, E View FIG ), several additional specimens of O. amblia ( Fig. 1C View FIG ), O. ephamilla ( Fig. 1F View FIG ), and of an undescribed species ( Fig. 1 View FIG G-I) (see description below) has led us to confirm the absence of pillar structure in all these taxa, which seem to form a natural group ( Anasser n. subgen.) unlike any other subgenus of Olivella , already described.

While the definition of a generic-level taxon based solely on conchological characters is a suboptimal situation, we feel the uniqueness of this group warrants such a measure.

The simplest kind of pillar structure among the Olivella is found in the subgenera Minioliva Olsson, 1956, Callianax H. & A. Adams, 1853 and Cupidoliva Iredale, 1924 ( Table 1). Besides that character, these subgenera share with Anasser n. subgen. a callus that does not extend beyond the upper end of the aperture.