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NUMBER 557 79
DISTRIBUTION.—Japan: Oki Strait, Honshu, Sea of Japan;
Osumi Strait, Kyushu; 100-144 m. Elsewhere: Off Durban,
South Africa; 138 m.
Truncatoflabellum sp. A
PLATE 34C -e
?Flabellum stabile Marenzeller, 1904a:273-274, pi. 17: fig. 12.—Zibrowius,
1980:150.
?Truncatoflabellum stabile.—Cairns, 1989a:61.—Zibrowius and Gili,
1990:39.
Truncatoflabellum sp. cf. T. stabile.—Cairns and Keller, 1993:264-265, fig.
10C.F.
DESCRIPTION BASED ON 2 SPECIMENS FROM TM (KT9202,
YT6).—Angle of straight thecal edges 60°-65°; inclination of
slightly convex thecal faces, 33°-34°. Thecal faces meet in
acutely angled edges that are quite long but that lack spines and
crests. Largest specimen: 42.6 x 26.5 mm in calicular diameter
and 40.5 mm in height, with a basal scar diameter of 2.1 x 6.0
mm. Calicular edge arched and finely serrate; GCD:LCD of
both specimens 1.61; GCD:H = 1.05-1.07. Basal scar small in
relation to corallum size: 2.1-2.6 x 5.0-6.0 mm. Even though
these specimens appear to have been collected alive, the theca
is quite worn and chalky in texture.
Septa hexamerally arranged in 5 complete cycles according
to the formula: S1_3>S4>S5, both specimens having 96 septa.
S^g wide, their lower, inner edges thickened and sinuous,
fusing with the medial columella. S4 about three-quarters width
of an S^_3 and do not fuse with the columella. S5 small, only
about one-quarter width of an S4. Fossa deep and elongate,
containing a well-developed columella about 3 mm in width.
DISCUSSION.—Five species of Truncatoflabellum are
characterized as having nonspinose and noncrested thecal
edges: T. paripavoninum (Alcock, 1898); 71 stabile (Marenzeller,
1904a); 71 inconstans (Marenzeller, 1904a); 71 trapezoideum
(Keller, 1981b); and Truncatoflabellum sp. (Zibrowius
and Gili, 1990). All but 71 inconstans are found exclusively in
deep water (600-3000 m). Having five cycles of septa, the
Japanese specimens must be compared to T. trapezoideum and
71 stabile, the other species having either four or six cycles of
septa. The Japanese specimens differ from 71 trapezoideum in
having a much smaller basal scar, nonridged costae; rounded
thecal edges; and a much taller corallum (having a lower
GCD:H ratio, 1.05-1.07 vs about 1.20 for F. trapezoideum).
They are, however, very similar to 71 stabile, especially to the
specimen reported from off Mozambique by Cairns and Keller
(1993). Because the types of F. stabile are lost and there are few
other specimens of this species with which to compare, the
identity of the Japanese specimens remains uncertain.
MATERIAL EXAMINED.—New Records: TM (KT9202,
YT6), 2, USNM 92810. Previous Records: Specimen reported
by Cairns and Keller (1993), IOM.
TYPES.—The two syntypes of Flabellum stabile are presumed
to be lost. Type Locality: Valdivia-31: 16°14'01"N,
22°38'03*W (Cape Verde Islands), 1694 m.
DISTRIBUTION.—Japan: Off Osumi Shoto, northern Ryukyu
Islands; 964-1031 m. Elsewhere: Off Cape Verde, Selvagems,
and Madeira Islands; off southeastern Mozambique;
1450-3010 m.
Truncatoflabellum sp. B
PLATE 33/,/
DESCRIPTION OF SPECIMEN FROM TM (KT9202, TY1).—
Corallum 5.9 x 3.1 mm in calicular diameter (GCD:LCD = 1.9)
and 17.8 mm in height, with a basal scar diameter of 3.7 x 2.3
mm. Thecal edges rounded and straight, virtually parallel to
one another as are the convex thecal faces. Thecal edges bear 6
pairs of small (0.4 mm in diameter), hollow spines. Thecal
faces porcellaneous and reddish brown in color, the pigmentation
stonger in crescent-shaped bands parallel to upper calicular
edge.
Septa hexamerally arranged in 3 cycles plus 4 pairs of S4 in
end half-systems for a total of 32 septa. S^_2 equal in size and
have sinuous inner edges that reach the columella. S3 half
width of Su2 and do not reach the columella unless they are
flanked by a pair of S4, in which case they are the same width
of an S^g. S4 small, only about one-quarter width of an S3.
Columella robust, about 1.1 mm wide.
DISCUSSION.—This species is distinguished from its congeners
by its virtually parallel thecal edges and elongate corallum.
Together with additional specimens from the Kermadec
Islands, these specimens will form the basis of the description
of a new species (Caims, in prep.).
MATERIAL EXAMINED.—TM (KT9202, YT1), 1, USNM
92811.
DISTRIBUTION.—Japan: Osumi Shoto, northern Ryukyu
Islands; 80-88 m. Elsewhere: Kermadec Islands.
Placotrochides Alcock, 1902b
DIAGNOSIS.—Corallum compressed-cylindrical; transverse
division present, resulting in an anthocyathus with a basal scar
almost as large at its calicular diameter. Thecal spines absent.
Three to four cycles of nonexsert septa; calicular edge smooth.
Columella well developed, trabecular.
TYPE SPECIES.—Placotrochides scaphula Alcock, 1902b,
by subsequent designation (Wells, 1936).
Placotrochides scaphula Alcock, 1902
PLATE 34/-*
Placotrochides scaphula Alcock, 1902b:121-122; 1902c:34, pi. 4: figs. 32,
32a.—Cairns, 1989a:78-79, pi. 40: fig. 1; pi. 41: figs, a-e [synonymy].—
Caims and Keller, 1993:272-273, fig. 12D.G.
DESCRIPTION.—Corallum shaped like a flattened cylinder,
with virtually parallel thecal faces and parallel, rounded thecal
edges. No edge spines. Largest Japanese specimen 10.0 x 5.4
mm in calicular diameter and 9.4 mm in height, with a basal
scar measuring 9.5 x 5.3 mm, almost as large as the calice.