What's A Rice Olive, Anyway?
By Harry G. Lee
|Among the many puzzling specimens in my collection are three somewhat similar lots of marine snail shells looking like tiny grains of white rice (Fig. 1). From left to right, these examples measure 3.9, 6.2, and 4.7 mm and originate (respectively) in a sediment sample taken at 60 ft. on Newport Reef, CURACAO by a physician colleague, Dr. Mike Loper, on 2/20/04; on the beach at Hopetoun, along the south coast of Western AUSTRALIA, found 1973, originally labelled "Ramoliva adiorygma (Verco, 1909)," and reaching me through Werner Massier on May 2, 2003; and in a cave in 30-35 m., off Old Shark Pt., Vilini Is., MALDIVES, collected on 11/13/94 and obtained from Ross Mayhew circa 1998.|
Each of these looks like an Olivella (sensu
lato) but at first inspection has no
pillar modification or fasciolar structure
(see "P" and "F" in Fig. 5),
which distinguishes this triad from any member of the generic group (sensu
lato) known from the Americas (Olsson, 1956), Australia (Wilson, 1994),
or in the largest assortment of world-wide species-level taxa (105 in
toto) treated in the literature (Kaicher, 1987).
In the same work Verco also named a somewhat similar
shell Olivella solidula (Ibid. p. 39; figs. 7, 8; our
Fig. 6). It was taken from
Encounter Bay, South Australia, quite near the type locality of O.
adiorygma and about 800 miles east of Hopetoun. He characterized it
as "solid, shining white, smooth, obliquely elongate-oval. Apex blunt,
four whorls, sloping convex, suture well channelled. Aperture oval,
contracting gradually to a linear gutter posteriorly, widely-open in
front, and notched; outer lip simple, smooth; inner lip is a narrow, thick
glaze over the base to the suture, slightly spreading over the columella
.... 6 mm. (by) ... 2.3 mm." As seen in Fig.
6, the shell has relatively narrowly-channeled sutures and
no evident fasciolar or pillar sculpture. The absence of the latter
features contrasts with Olivella [now Belloliva]
exquisita Angas, 1871, which Verco wrote "it closely resembles [but
differs] in being smaller, narrower and pure-white." A solitary specimen
which matched the type illustration of Olivella solidula was found
in my lot of Hopetoun Ramoliva adiorygma. Most regrettably, this
shell was accidentally crushed in preparation for scanning. Our
Fig. 7 is a 8.2 mm B. exquisita in my
collection taken near
shore, Cogee Bay, NSW, Australia. An image of another specimen whitened
with magnesium oxide (Kaicher, 1987; card 4966;
Fig. 8) more clearly demonstrates the pillar and fasciolar
features, which are absent from Olivella solidula.
Rosenberg, G. and R. E. Petit, 2003. Kaicher’s card catalogue of
world-wide shells: a collation with discussion of species named therein.
The Nautilus 117(4): 99-120. Dec. 23.
|Wilson, B., 1994. Australian marine shells prosobranch gastropods part two (neogastropods). Odyssey, Kallaroo, W. A. pp. 1-370.|
|** The Card catalogue of world-wide shells was published from 1973-1992 comprising some 6421 3 in. X 5 in. cards, of which 121 were general and introductory and 6300 treated (illustrated) single species; most cards consecutively numbered, some duplicate numbers, some numbers skipped, some un-numbered but assigned numbers later; issued in 60 lots of between 96 and 108 species cards per lot; many primary museum types depicted; also see Rosenberg and Petit (2003).|