Bulletin 20 - Peabody Museum of Natural History - Yale University

24 A SYSTEMATIC STUDY OF THE DEMOSPONGIAE OF JAMAICA
GENUS IOTROCHOTA Ridley
Iotrochota birotulata (Higgin) Ridley
Halichondria birotulata Higgin, 1877, p. 296 [type: Venezuela; Brit. Mus. (Nat. Hist.) (?)]
[non] Halichondria birotulata, Carter, 1886, p. 52 (fide Dendy, 1896); idem, 1887, p. 72.
Iotrochota birotulata, Ridley, 1884, p. 433; de Laubenfels, 1932a, p. 37; idem, 1936a, p.
49; idem, 1953a, p. 522.
HABITAT. Common on pilings at Port Royal and on coral masses offshore from the
cays.
SHAPE. Typically ramose with branches 1-2 centimeters in diameter. One massive
specimen was collected.
COLOR. Very dark purple, nearly black, with a greenish surface sheen in life. A
purplish slime is emitted when the sponge is handled. Dried and preserved specimens
are purplish black.
CONSISTENCY. Tough, rather stiff.
SURFACE. Numerous conules and connecting ridges make the surface very uneven.
The narrow sharp-pointed conules are 1-3 mm in height and 1-8 mm apart. The shallow
depressions between the elevated areas are covered by a thin skin. The oscules are small,
scattered and infrequent. Orange zoanthids are present on the surface.
ECTOSOME. The skin contains sparsely scattered, long, thin styles and numerous
birotules. It is pierced by numerous ostia which are 20-30 fi in diameter. In places, the
surface is underlain by subdermal cavities which are often 200 /x in depth.
ENDOSOME. The skeleton includes a reticulation of spicule bundles and scattered
interstitial megascleres. Birotules are most abundant near the canals and periphery
The spicule tracts are 35-180 p in diameter and 170-650 ^ apart. Stout bundles extend
into the conules. No localization of megasclere types could be detected in the endosome.
A specimen collected during November, 1960, contains numerous densely pigmented
aspiculous embryos, as large as 500 /x in longest diameter.
SPICULES, (a) Strongyles, mostly curved, 117-286 p, in length. The diameter varies between
3-8 /x, with the longest spicules typically thin and occasionally anisostrongylote.
(b) Styles, less frequent, mostly curved, 129-253 x 5-10 /*. The longer spicules, such as
those in the ectosome, are frequently thin, (c) Oxeas, hastate, rare or absent, 152-188 p.
Their diameter is similar to that of the styles and strongyles. (d) Birotules, 10-18 /JL in
length.
Individual analyses, lengths in microns:
Strongyles
Styles
Oxeas Birotules
117-217 (50)
140-246 (50)
117-258 (50)
152-286 (50)
present
- present
present
130-182 (50)
159-253 (30)
129-193 (30)
130-186 (30)
present
present
present
152-188 (25)
183 (1)
none
163 (2)
rare
rare
rare
13-16 (25)
13-17 (25)
12-14 (25)
12-15 (25)
13-18 (25)
13-17 (25)
10-13 (25)
DISTRIBUTION. Tropical Atlantic America: Dry Tortugas, Florida—de Laubenfels,
1932a, p. 37, 1936a, p. 49; West coast, Florida—de Laubenfels, 1953a, p. 522; Venezuela—
Higgin, 1877, p. 296 (as Halichondria birotulata); Bahamas—Higgin, 1877, p. 296 (as
Halichondria birotulata); Jamaica—Higgin, 1877, p. 296 (as Halichondria birotulata),
de Laubenfels, 1932a, p. 37; Indo-Pacific: Mergui Archipelago, off Burma—Carter, 1887,
p. 72 (as Halichondria birotulata)(?).
DISCUSSION. Oxeas are known to occur in the genus, being common, for example, in
I. acerata Dendy (1896). They have not been recorded previously for 7. birotulata. Although
rare at best, their uniformity of shape indicates that they are proper to the
sponge.
De Laubenfels reported that the birotules may be rare or absent. Higgin's sponge