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58
mm in calicular diameter and 22.2 mm in height. Costae on
thecal perimeter slightly convex and granular, the Cu2 being
slightly wider than other costae and ridged near the calice.
Corallum white.
Septa hexamerally arranged in 5 cycles, the last incomplete,
according to the formula: S1_2>S3>S4»S5. Large specimens
(e.g., GCD > 40 mm) have only 72 septa, whereas mid-sized
coralla of GCD 25-37 mm have only 64-70, and smaller
coralla 18-25 mm GCD have 50-68 septa. No specimens were
found with only 48 septa. Half-systems within a single
specimen quite variable in development, some having 0, 2, or
4 S5. S^ highly exsert (about 5 mm), each bearing a low,
oblique to almost horizontally projecting paliform lobe that
extends into the columellar region. S3 slightly less exsert
(3.0-3.5 mm), each also bearing a small paliform lobe but
positioned slightly higher in fossa and slightly farther from
columella than P^. S4 smaller still (only about 2.7 mm exsert),
each bearing a wide paliform lobe which contributes to a palar
crown that is located higher and farther recessed from the
columella than the P3 crown. Inner edges of P4 usually bend
toward and are fused to P3 near columella. S5 rudimentary,
extending as narrow lamellae only partially down inner theca.
When S5 are absent from a half-system, the S3 bears a wide
paliform lobe equal in size and position to that of a P4. All septa
have very finely sinuous inner edges and virtually smooth
septal faces. All paliform lobes separated from their respective
septa by broad, shallow notches. Fossa moderately deep,
containing a papillose columella.
DISCUSSION.—Stephanocyathus weberianus is very similar
to the type-species of the subgenus, 5. (O.) coronatus
(Pourtales, 1867), which is known only from the western
Atlantic at 543-1250 m (Cairns, 1979). A detailed comparison,
however, reveals that S. coronatus invariably has only 12 large,
often complexly ornamented costal tubercles, whereas S.
weberianus has 12-18 rather simple tubercles that are usually
quite worn. The base of S. coronatus is usually convex and
coarsely dentate (C^_2)\ that of 5. weberianus is flat and eroded.
The corallum of 5. coronatus is, in general, higher in proportion
to its diameter (H:D) than S. weberianus in proportion to its
diameter, producing a more slender corallum with less septa.
For instance, coralla containing only 48 septa are common for
S. coronatus but quite rare for S. weberianus, the latter often
having half-systems with a full complement of 4 S5. Finally,
the S3_5 of S. coronatus are less exsert in relation to their S,_2
than in S. weberianus.
Stephanocyathus weberianus is also similar to 5. nobilis
(Moseley, 1873), known only from the Atlantic and western
Indian Oceans at 609-2200 m (Cairns and Keller, 1993). Zou
(1988) synonymized the two species, considering S. nobilis to
be a cosmopolitan species in the Atlantic, Pacific, and Indian
Oceans. However, when closely compared, S. nobilis differs
significantly in having very inconspicuous paliform lobes and
in lacking costal tubercles, having only a series of large costal
spines on the C^. Furthermore, its costal spines are limited to
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
the twelve C1-2, even when a half-system has all 4 S5, whereas
additional costal tubercles are invariably present in specimens
of 5. weberianus having the same number of septa. Stephanocyathus
nohilis also has an evenly rounded, convex base, and,
like S. coronatus, much more exsert S^ in relation to the
remaining S3.5.
The difference between 5. weberianus and S. sibogae as
described by Alcock (1902a) was that the former had a swollen
ring around its base, the latter, a worn base with atrophied
costal tubercles. It is now clear that these conditions are within
the range of variation for one species: S. weberianus.
MATERIAL EXAMINED.—New Records: Alb-4908, 1,
USNM 92734; Alb-4909, 2, USNM 92735; Alb-4911, 1,
USNM 92736; Alb-4957, 4, CAS 1102; Alb-4958, 1, USNM
92737; Alb-4959, 1, USNM 92738; Alb-4960, 2, USNM
92739; Alb-4969, 2, USNM 82159; Alb-4973, 3, USNM
92740; Alb-4975, 1, USNM 92741; TM (KT9202, ATI), 2,
USNM 92742; TM (KT9202, YT6), 10, USNM 92743,4, ORI.
Previous Records: Holotype of 5. weberianus, ZMA; Alb-
5445, 46, USNM 46819 (5. ixine of Squires, 1958).
TYPES.—The holotype of S. weberianus is deposited at the
ZMA (Coel. 1322). Type Locality: Siboga-2%A: 8°43.1'S,
127° 16.7'E (Timor Sea), 828 m.
The holotype of 5. Sibogae is presumed to be deposited at the
ZMA, but is not listed by van Soest (1979). Type Locality:
Siboga-%%: 0°34.6TSf, \\9°Q%.5 f E (Makassar Strait),
1301 m.
DISTRIBUTION.—First reports from off Japan: Off southeastern
Honshu; Bungo Strait; off Koshiki I., southwestern
Kyushu; northen Ryukyu Islands (Osumi Shoto and Tokara
Retto); 715-1302 m. Elsewhere: South China Sea, Sulu Sea,
Makassar Strait, Banda and Timor Seas; 206-1301 m.
Conotrochus Seguenza, 1864
DIAGNOSIS.—Solitary, ceratoid to trochoid, free or attached
through a small pedicel, which is often augmented by a lateral
thecal attachment. Theca thick, but covered with epitheca;
costae usually obscure. Septa exsert, but upper outer septal
edges join the theca below upper thecal edge, forming an exsert
calicular rim. Pali absent; columella prominent, composed of
elongate, twisted lamellar elements.
TYPE SPECIES.—Conotrochus typus Seguenza, 1864, by
original designation.
Conotrochus funicolumna (Alcock, 1902)
PLATES 24/, 25g-l
Ceratotrochus (Conotrochus) funicolumna Alcock, 1902a:93; 1902c: 11-12,
pi. 1: figs. 6, 6a.—Faustino, 1927:66, pi. 9: figs. 7, 8.—Yabe and Eguchi,
1942b:117. pi. 9: fig. 11.—Eguchi, 1968:C38-39.—Zou, 1988:77, pi. 5:
figs. 1, la.
Conotrochus funicolumna.—Cairns, 1984:14, pi. 2: figs. IJ.
Conotrochus sp. cf. C. funicolumna.—Cairns and Parker, 1992:22, pi. 6:
figs, c, f.
Ceratotrochus hiugaensis Yabe and Eguchi, 1942b:117, 146, pi. 9: fig.