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

7. Family Euretidae; Genus nov., sp. nov. Reiswig and Stone, in preparation
Description. Tall, circular, rigid funnel is attached
to hard substrate, with small hollow digitate processes
projecting from all lateral surfaces. In life the lateral
processes are closed distally by tissues and loose spicules,
but the fused skeletal framework is open at the ends.
The single large circular osculum at the distal end has a
crenulate margin. All surfaces are smooth to the naked
eye, but under low magnification they are seen to be
ornamented with fine hairs of projecting uncinate spicules.
Consistency is hard and rigid. Height is to 29.2 cm
and diameter to 13.7 cm; lateral processes 6–12 mm in
diameter and up to 24 mm long are distributed rather
evenly without pattern and commonly divide into two
or three short branches in larger specimens. Color in
life is yellow-orange to light orange.
Skeletal structure. The primary rigid skeleton of
fused hexactine spicules has elongate meshes with
longitudinal strands and radial septa, similar to the
primary framework of Chonelasma. That framework
curves smoothly out into and continues through the
digitate processes. Slight indications of irregular dermal
and atrial cortices are present, but they are usually
only one dictyonalium in thickness. There are several
types of loose megascleres: pinular hexactins on inner
and outer surfaces of wall and processes, with thorned
pinulus (67–287 µm long); tangential rays spined at the
tips (88–196 µm long); proximal ray (79–954 µm long);
simple hexactins and pentactins in subatrial position of
wall and processes (106–518 µm ray length); tauactins
only in spicule pads at tips of processes (158–479 µm ray
length); diactins in atrial surface of wall and processes
(88–196 µm ray length); discoscopules on both surfaces
of wall and processes (234–480 µm long); tyloscopules
only echinating atrial surface of processes (619–952
µm long); uncinates echinating both surfaces of wall
and processes (656–2785 µm long). Microscleres are
mainly discohexactins (76%; 52–98 µm in diameter),
moderately common oxyhexactins (20%; 34–94 µm
in diameter), and few hemidiscohexasters (4%; 46–
100 µm in diameter).
Zoogeographic distribution. Locally common. In
Alaska – central Aleutian Islands. Elsewhere – not
reported.
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Habitat. Occurs singly or in small patches on exposed
bedrock, mudstone, boulders, and cobbles at depths
between 773 and 2084 m.
Remarks. Juvenile Verrill’s Paralomis crabs (Paralomis
verrilli) use the spongocoel as refuge habitat (Stone,
unpubl. data, 2004).
Photos. 1) Whole specimen collected at a depth of
1256 m in the central Aleutian Islands. Grid marks are
1 cm 2 . 2) Same specimen as in photo 1 in situ.