Fenimorea marmarina (Watson, 1881) Watson, 1881

Fallon, Phillip J., 2016, Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species, Zootaxa 4090 (1), pp. 1-363 : 183-184

Fenimorea marmarina (Watson, 1881) , new combination

( Plate 86 )

Pleurotoma (Perrona) marmarina Watson, 1881:429 : Watson (1886: 328, pl. 24, fig. 8).

Drillia (Clavus) marmarina (Watson, 1881) : Tryon (1884 [list]).

Pleurotoma marmarina (Watson, 1881) : Paetel (1888 [list]).

Clavatula marmarina (Watson, 1881) : Rios (1975:130, pl. 39, fig. 576 [Watson’s fig.]); Rios (1985:134, pl. 46, fig. 610 [Watson’s fig.]); Rios (1994: 170, pl. 56, fig. 776 [Watson’s fig.]).

Not this species and unconfirmed or extralimital reports.

Drillia marmarina (Watson, 1881) : Absalão et al. (2005: 23, fig. 10 [Color pattern like F. fucata ; not all white as in type]); Rios (2009: 307, fig. 775 [Photo from Absalão et al. (2005)]).

Type material. Holotype 16.8 x 7.4 mm (MNHUK 1887.2.9.103). The holotype was not examined directly; instead, a photographic image of the holotype, supplied by the NHMUK, was used to represent the species. Type locality. HMS Challenger Sta. 122, off Pernambuco, Brazil, 9°05'S, 34°50'W, in 350 fms [640 m]. Range and habitat. Known only from the holotype.

Description. Shell small (type 16.8 mm total length, but incompletely developed), fusiform, truncated anteriorly, with 10 convex whorls, the last approximately 64% of total height. Predominant sculptural element of axial ribs; aperture moderately wide; anterior canal short. Protoconch of 2 smooth whorls. Axial sculpture of narrow nearly straight convex ribs that run from suture-to-suture on spire whorls, evanesce on last near anterior fasciole; ribs number 15 on last whorl, crests ridged. Ribs convex, abruptly lower, and slightly curved in sulcus, reflecting outline of anal sinus. Varix lacking on type. Spiral sculpture of grooves (18 or 20 on last whorl) with interspaces three times their width overriding microscopic spiral threads that are made jagged by even finer growth striae. This pattern is present on most of the rib surface but obscure on crests. Sulcus well demarcated by a deep furrow; is approximately ⅓-spire whorl height. Ribs present but lower and curved, reflecting outline of the anal sinus. Surface microsculpture the same as on the whorl proper, but lacks spiral grooves. Outer lip thin, not fully developed; no stromboid notch present. Anal sinus on shoulder adjacent to suture, round. Not fully developed in the type specimen. Inner lip thin, narrow, recumbent on canal and parietal wall; not emarginated. No parietal lobe has formed on the incompletely developed type specimen. Anterior canal open, very short, barely distinguishable from the aperture; fasciole not swollen. Surface of fasciole with spiral threads. Color all white.

Remarks. Taxonomy. Watson’s type has not been examined directly; however, from his detailed description and from the photograph supplied by the NHMUK the shell microsculpture is consistent with members of Fenimorea : “The whole surface is very delicately fretted with almost microscopic, crisp spiral striae, whose course is not quite regular, and which are crimped or disturbed by the lines of growth; this sculpture is particularly sharp and distinct in the sinus area.”(Watson, 1886: 323) The holotype appears to be an immature specimen because the lip is thin, aperture is without a parietal lobe, and the varix has not formed. Identification. The type of F. marmarina may be confused with other all-white species of Fenimorea . It is similar to F. phasma (Schwengel, 1940) , F. alba , new species, and F. ni v al i s, new species. From F. phasma it differs in being smaller, and in possessing more convex ribs in the sulcus. Ribs in the sulcus of F. phasma are flat to concave. From F. alba it differs in having broader axial ribs and a more robust last whorl. From F. nivalis it differs in being larger and more robust.

Figures

PLATE 86. Fenimorea marmarina (Watson, 1881). Fig. 1: holotype, off Pernambuco, Brazil (NHMUK 1887.2.9.103). Images courtesy of the NHMUK.