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