Vol. 92 (2)
April 27, 1978
The Nautilus 85
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FUSINUSSTEGERI {GASTROVODA: FASCIOLARIDAE), A NEW SPECIES
FROM THE EASTERN GULF OF MEXICO'
William G. Lyons
Florida Department of Natural Resources
Marine Research Laboratory
St. Petersburg, Florida 33701
ABSTRACT
Fusinus stegeri n. sp. from 100-205 frns (183-375 m) depths off western Florida
differs from F. eucosmius (Dcdl 1889) by its greater length (to 102 mm), white col-
or, and diminishing strength of axial ribs on anterior whorls. Fusinus eucosmius is
knoum only to depths of 89 fms (162 m). Twenty-six other names applied to
ivestem Atlantic Fusinus are listed.
(Commercial shell dredging during the past sev-
eral years has resulted in increased availability
of many deep water west Florida mollusks. A
species of Fusinus common among private shell
collections is here described. Specimens of the
new species are deposited in collections of the
Academy of Natural Sciences of Philadelphia
(ANSP), Pennsylvania, the American Museum of
Natural History (AMNH), New York, New York,
the British Museum (Natural History) (BMNH),
London, the Museum of Comparative Zoology
(MCZ), Cambridge, Massachusetts, the National
Museum of Natural History, Smithsonian Institu-
tion (USNM), Washington, D.C., and the Florida
Department of Natural Resources Marine Re-
search Laboratory (FSBC I), St. Petersburg.
Fusinus stegeri, new species
(Figures 1-5)
Description: Shell large, to at least 102 mm
' Contribution no. 317. Florida Department of Natural
Resources, Marine Research Laboratory.
total length, slender, fusiform, with about 13
whorls. Embryonic whorls about 2'/2, small,
elongate, flattened apically, with only slightly
convex lateral margins; last half whorl with
strong axial riblets. Nearly 11 postembryonic
whorls bearing prominent, swollen axial ribs, in-
creasing numerically but decreasing in strength
anteriorly; first five spiral whorls with 6 or 7
ribs, sixth whorl nearly always with 7 ribs, sev-
enth with 8-10, eighth with 9-13, ninth with
10-14, and tenth with 13-16 ribs. Spiral whorls
rounded, with strongly convex sides and con-
stricted sutures; each whorl crossed by 6-8, usual-
ly 7, prominent spiral cords. About 10 or 11
strong cords on body whorl, 9-12 on base,
sometimes with weaker cords between. Aperture
ovate, slightly constricted anteriorly and
posteriorly; parietal callous extended, forming
sharp, thin lamina (inner lip) along columellar
border of aperture ; lamina sometimes present but
reduced along columellar zone of anterior
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