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Tropidocyathus pilots (Alcock, 1902)
PLATE 29d,e
Trochocyathus pile us Alcock, 1902a:96-97; 1902c:15-l6, pi. 2: figs. 11,
1 la.—Yabe and Eguchi, 1942b:123, pi. 10: figs. 19,20.—Eguchi, 1965:286,
2 figs.
Trochocyathus (Tropidocyathus) intermedius Yabe and Eguchi, 1932b:443
[notnen nudum].
Tropidocyathus pileus.—Caims, 1989a:34-35, pi. 17: figs, a-h [synonymy].
DESCRIPTION.—Looking at a lateral face, the corallum is
trapezoidal, the lower lateral edges being either rounded or
slightly protuberent, but never carinate (crested). Largest
Japanese specimen examined (TM (KT9015, BS2)) 18.7 x 11.0
mm in calicular diameter and 19.5 mm in height. Costae
continuous from calice to base, where many are continuous
with their counterparts from the opposite face. Edge protuberances,
if present, vertically costate and not granular. Costae
rounded and equal in width, each bearing an outer unilinear row
of coarse teeth, as well as smaller granules on their lateral faces.
Intercostal furrows deep. Corallum white.
Septa hexamerally arranged in 4 cycles, larger specimens
having pairs of S5 in their end half-systems, e.g., the illustrated
specimen has 6 pairs of S5 for a total of 60 septa. S1 about 2
mm exsert and have slightly sinuous inner edges, each S1
bordered by a small (about 0.8 mm wide), highly granular palus
that is positioned directly adjacent to the columella. S2 only
slightly less exsert and about 80% width of an S^ each S2 also
bearing a palus of equal width and position to that of the P1 but
rising higher in the fossa. S3 least exsert septa (only about 1
mm) and about two-thirds width of an S2, each having a broad
(about 1.5 mm wide) palus slightly recessed from the columella
and rising higher in the fossa than the P2. Each pair of P3 within
a system slant toward their flanked P2, the inner edges of these
triads (1 P2 and 2 P3) sometimes loosely fused into a chevron
arrangement. S4 slightly more exsert and wider than S3, their
outer edges fused to adjacent S^ at calicular edge producing
calicular projections that result in a serrate calicular margin. P4
present only if pairs of S5 present in a half-system. Fossa of
moderate depth. Columella linear-papillose, the elements
strongly fused together into a solid lamella.
DISCUSSION.—The name Tropidocyathus intermedius (Yabe
and Eguchi, 1932b), attributed to a Pleistocene fossil coral, was
never described but nonetheless was synonymized by Yabe and
Eguchi in 1942(e). A second Pleistocene specimen from the
same general region is reported herein.
Comparisons to T. lessoni are made in the account of that
species. A more complete description and illustration of T.
pileus can be found in Cairns (1989a).
MATERIAL EXAMINED.—New Records: TM (KT9015,
BS2), 6, USNM 92781,1, ORI; TM (KT9202, OS2), 2, USNM
92780; TM (KT9309, AM8), 11, ORI, 5, USNM 93164; USGS
17445, 1.6 km west of Yonabaru, Okinawa, Ryukyu Islands,
Pleistocene, 1, USNM 88673. Previous Records: Syntypes of
Trochocyathus pileus, ZMA.
TYPES.—Four syntypes of T. pileus are deposited at the
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
ZMA (Coel. 7352). Type Locality: Siboga-95: 5 0 43TSf,
119°40'E (Sulu Sea), 522 m.
DISTRIBUTION.—Off Japan: Suruga Bay, Honshu; off Shikoku;
off southern Kyushu; off Amami Oshima, Ryukyu
Islands; 123-422 m. Pleistocene of Ryukyu Islands. Elsewhere:
South China Sea, Philippines, off southeastern Australia,
?Gulf of Manaar; 123-522 m.
Alatotrochus, gen. nov.
DIAGNOSIS.—Corallum cuneiform, with a rounded (free)
base and prominent, costate thecal edge crests. Theca imperforate.
Costae serrate, extending from calice to base; costae
number twice that of septa. Four cycles of highly exsert septa.
Pali absent; columella linear-papillose.
DISCUSSION.—Using my key to the turbinoliid genera
(Cairns, 1989a:25-26), Alatotrochus would key to Platytrochus,
the genus in which Moseley (1876) originally placed the
type species. Alatotrochus does share several characters with
Platytrochus, such as a cuneiform corallum with edge crests, a
papillose columella, and the absence of pali. Alatotrochus
differs from the type species, Platytrochus stokesi (Lea),
however, in several significant characters. It has a much larger
corallum, an additional cycle of septa, and twice as many costae
as septa. Its costae are serrate and continuous from calice to
base, whereas those of P. stokesi are discontinuous and
granular. Finally, its columellar elements are large and linearly
arranged, whereas those of Platytrochus are much smaller and
grouped in an elliptical field or two rows.
Moseley (1881) later placed Platytrochus rubescens in the
genus Sphenotrochus, which is not surprising given the
similarity of Platytrochus and Sphenotrochus (see Cairns,
1989a: 38). Nonetheless, Alatotrochus differs from species of
Sphenotrochus in having a papillose (not lamellar) columella;
a larger corallum; serrate (not smooth) costae; and twice as
many costae as septa.
Alatotrochus is monotypic.
ETYMOLOGY.—The name Alatotrochus (Latin alatus, meaning
"winged" + trochus, a common coral suffix, literally
meaning "wheel"), refers to the prominent edge crests of this
genera that resemble wings. Gender: masculine.
TYPE SPECIES.—Platytrochus rubescens Moseley, 1876,
here designated.
DISTRIBUTION.—Bungo Strait, off Kyushu; off Amami
Oshima, Ryukyu Islands; 193-422; Banda Sea, 236 m;
Pleistocene of Okinawa, Ryukyu Islands.
Alatotrochus rubescens (Moseley, 1876), comb. nov.
PLATE 29/J-/
Platytrochus ruhescens Moseley, 1876:553.
Sphenotrochus rubescens.—Moseley, 1881:157-159, pi. 6: figs. 8, 8a.
DESCRIPTION.—Corallum compressed, very much resembling
the shape of Tropidocyathus lessoni, with thin, solid (not
hollow) edge crests extending as much as 4 mm from the thecal