Fróðskaparrit - 01.01.2004, Page 302

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FRESHWATER SPONGES (PORIFERA: SPONGILLIDAE) IN THE FAROE ISLANDS
Genus Spongilla Lamarck, 1816
Spongilla lacustris (Linne, 1758)
Good general description: Penney and Racek (1968: 9,
pl. 1), Pronzato and Manconi (2001: 38, Figs. 29-31).
Previous records: none.
New records: Bøsdalafossur, Vágar (F. Jensen,
16.07.1978); Leynavatn, 0.5 m, Stremoy (O.S. Tendal,
28.09.1991); Mýranar, 3-10 m, Stremoy (H.T. Rapp,
23.09.1997).
Material deposition: Natural History Museum,
Aarhus and Zoological Museum, Copenhagen.
Description of the material (Figs. 2 and 3): The
specimen from Bøsdalafossur is a small rounded lump,
2 cm in maximum diameter. There are no gemmules and
no trace of substrate. The smooth megascleres measure
250-325 pm in length (average 291 pm). The spiny
microscleres measure 70-110 pm in length (average 86
pm).
The material from Leynavatn is encrusting, up to 1
cm thick and 20 cm in diameter. In life it was green, soft
and had the characteristic freshwater sponge smell. The
substrate was a stone in the bottom of a small stream.
The smooth megascleres measure 200-325 pm in length
(average 241 pm). The spiny microscleres measure
70-100 pm in length (average 81 pm). The spiny
gemmoscleres measure 50-90 pm in length (average 72
pm).
The material from Mýranar near Vestmanna has a
well developed basal encrusting part from which grow
up to 6 cm (according to diver’s report 25 cm) long
undivided branches, about 0.5 cm in diameter. It was
soft and the live colour was yellowish to light brown.
The substrate seems to have been large sand grains or
small pebbles scattered in the mud on the bottom of
the lake. The smooth megascleres measure 275-375
in length (average 341 pm). The spiny microscleres
Fig. 3. Spicules o/Spongilla
lacustris (After Weltner, 1909).