Olivella (Olivina), d'Orbigny, 1841

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 : 183-185

Subgenus Olivina d’Orbigny, 1841

TYPE SPECIES. — Olivella tehuelchana d’Orbigny, 1841 , by subsequent designation by Olsson (1956): Recent, southern Atlantic.

DIAGNOSIS. — Parietal callus thin, usually transparent, extending beyond the aperture toward the suture. Pillar structure is a low, simple or double fold at the end of columella, the wall above it smooth. Outer lip without lirae inside. Chitinous operculum present.

Olivella (Olivina) hyphala n. sp. ( Fig. 2 A-C) TYPE MATERIAL. — Holotype: MNHN; paratypes (two shells in each lot): MNRJ 8914 , 8917 ;

IBUFRJ 11914 ; MORG 41051; MZSP 35534; ZMA 402931; ANSP 410279. All from the type locality.

TYPE LOCALITY. — Abrolhos continental slope, Brazil ; MD-55, stn DC75, 18°59’S, 37°50’W, 295 m.

OTHER MATERIAL EXAMINED. — MD-55, stn DC75, 18°59’S, 37°50’W, 295 m, 27.V.1987, + 150 spec. ( MNHN) ; MD-55, stn DC63, 29°00’S, 37°48’W, 607-620 m, 27.V.1987, 32 spec. ( MNHN) ; MD-55, stn DC65, 18°59’S, 37°50’W, 295 m, V.1987, 6 spec. ( MNHN) ; MD-55, stn DC73, 19°00’S, 37°48’W, 607-620 m, V.1987, 17 spec. ( MNHN) .

ETYMOLOGY. — From hyphalos (Greek): under the sea, in the deep, concerning the relatively deep waters where this species inhabits.

DESCRIPTION

Shell large (reaching 12.0 mm length), subovate, homogeneously light cream in color, glossy, with a white subsutural belt. Spire moderately elevated, of three whorls, and about 48% the total length. Protoconch relatively low and large, forming a blunt apex. Sutures anterior to a wide channel. Fasciole line double. Parietal callus light, semi-translucent and relatively narrow, reaching the end of the aperture or a little above it, but never above the middle of the last whorl. Pillar structure smooth or with one or two folds in an inflexion of parietal wall, remainder smooth and almost straight. Younger forms are, usually, more inflated than adults. Deep water species (300- 600 m depth). Known only from empty shells.

REMARKS

The form of shell of O. hyphala n. sp. ( Fig. 2A ) is relatively big-belled and distinguishes it from more slender taxa as O. (Olivina) plata (Ihering, 1909) , O. (Olivina) orejasmirandai Klappenbach, 1964 and O. (Olivina) tehuelcha . It is close to O. (Olivina) riosi Klappenbach, 1991 and O. (Olivina) puelcha (Duclos, 1840) . While O. puelcha is colored by tones of yellowish-brown or orange, O. hyphala n. sp. is devoid of colors except the milk-white subsutural belt. Additionally, O. hyphala n. sp. shows a double fasciolar line, while it is simple in O. puelcha .

Olivella riosi is very variable in the shell form but is always less inflated than O. hyphala n. sp., both species share a double fasciolar line but the parietal calus in O. hyphala n. sp. is more lighty than in O. riosi .

Olivella hyphala n. sp. can be distinguished from O. klappenbachi n. sp. by its high spire. It may be distinguished from all other Olivina species by its subsutural band. Finally, the two new Olivina species differ conspicuously in bathymetric range from all previously recorded members of the subgenus – the next deepest record being 87 m ( Rios 1994), for Olivella (Olivina) riosi .

Olivella (Olivina) klappenbachi n. sp. ( Fig. 2D, E )

TYPE MATERIAL. — Holotype: MNHN; paratypes: MNRJ 8916 ; IBUFRJ 11913 ; MORG 41050; ANSP 410281. All from the type locality.

TYPE LOCALITY. — South of Cabo Frio, Rio de Janeiro State, Brazil , MD-55, stn CB105, 23°47’S, 042°10’W, 610 m.

ETYMOLOGY. — Olivella klappenbachi n. sp. is named after Dr Miguel Klappenbach from Montevideo Museum, Uruguay, who has studied the South American Olivella .

DESCRIPTION

Shell medium sized (about 6.0 mm length), roughly obconic, resembling a whirligig; color dirty cream. Parietal callus and aperture white. Callus broad, strong, sometimes forming like a rounded projection near the end of aperture. Parietal callus well developed, opaque, continuing a bit over the end of aperture but hardly reaching the middle of whorl. Pillar structure simple with one fold on the posterior end, remainder smooth. Parietal wall almost straight except the most anterior end where it is concave. Pillar structure does not extend into the aperture. Spire low to very low, suture broad and channeled, protoconch large and rounded, apex blunt. Fasciole simple. Operculum and radulae unknown, only empty shell collected. Deep sea species (610 m depth).

REMARKS

The whirligig-shaped, stout profile ( Fig. 2D ) is the main distinctive character of O. klappenbachi n. sp. This species and the variable O. (Olivina) riosi share the double fasciolar line, but it is clearly deeper in O. klappenbachi n. sp. The parietal callus of O. klappenbachi n. sp. is also somewhat thicker than in O. riosi . The protoconch width in O. klappenbachi n. sp. is approximately twice that of O. riosi .

Despite the shell form variability showed by O. riosi which, sometimes, superficially looks like a teetotum, it is mainly more oblong than O. klappenbachi n. sp. and due to its shell form the spire in the former species is lower than in O. riosi .

Olivella riosi usually has yellowish lines or flames on the shell, but the pattern, if any, of O. klappenbachi n. sp. remains unknown because all specimens were dead-collected and devoid of color.

Figures

FIG. 2. — Subgenus Olivina d’Orbigny, 1841; A-C, Olivella hyphala n. sp., holotype (MNHN); A, apertural view, 7.4 mm length; B, apex detail; C, plicae detail; D, E, Olivella klappenbachi n. sp., holotype (MNHN); D, apertural view, 5.5 mm length; E, apex detail. Scale bars: B, C, E, 500 µm.