A guide to the deep-water sponges of - NMFS Scientific Publications ...

21. Caulophacus (Caulophacus) sp. nov. Reiswig and Stone, in preparation
Description. A very large mushroom-shaped body
on a long cylindrical stalk attaches basally to hard substrate.
The inhalant surface occupies the upper stalk
and underside of the body; the exhalant surface on the
upper body is reflected around the edges to the sharp
margin on the under edges of the body; there is no distinct
osculum. All surfaces are macroscopically smooth
with large canals covered by lattices of loose spicules.
Consistency of the body is compressible but firm; the
stalk is stony hard due to fusion of the internal spicules
and is hollow, with two main internal longitudinal
canals. The specimen, measured dry, is 75 cm in total
height, the body is 31 by 40 cm transversely, and the
stalk is 68 cm long and 2.1 cm in diameter (narrowest
point, 1.8 cm). Color in life is white to creamy white;
drab when preserved.
Skeletal structure. Spicules in the main body remain
loose, but the principal diactins in the stalk are fused
to form a hard, rigid, and long-lasting structure. Megascleres
include pinular hexactine dermalia (132–337
µm pinular ray length, 90–163 µm tangential ray length,
102–158 µm proximal ray length); supported by hypodermal
pentactins (315–862 µm tangential ray length,
312–1054 µm proximal ray length); atrialia are slightly
thinner pinular hexactins (131–379 µm pinular ray
length, 80–167 µm tangential ray length, 88–142 µm
proximal ray length); supported by hypoatrial pentactins
similar to those of the dermal side; choanosomal
diactins are mainly in loose bundles (1.65–4.06 mm
long); large choanosomal oxyhexactins are common
(678–1579 µm ray length). Microscleres are all coarsely
spined, including hemidiscohexasters and discohexasters
(82–177 µm diameter) and discohexactins (90–185
µm diameter).
Zoogeographic distribution. Uncommon. In Alaska
– central Aleutian Islands. Elsewhere – not reported.
Habitat. Occurs singly on bedrock and large boulders
at depths between 1326 and 2680 m.
Remarks. The Aleutian Caulophacus (Caulophacus)
specimen has been compared to the 18 known species
of the subgenus and found to be unassignable to any of
them. Its description as a new species is in progress. It
is used as a perch by several species of lithodid crabs,
including Paralomis verrilli.
Photos. 1) Whole specimen collected at a depth of
1806 m in the central Aleutian Islands. 2) Same specimen
as in photo 1. 3) Same specimen as in photos 1
and 2 in situ with Paralomis verrilli crabs. The separation
between the red laser marks is 10 cm.
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