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Description

Myxilla asigmata, Topsent.

 

M. spongiosa, var. asigmata, Topsent, 1901, p. 18; Lissodendoryx spongiosa, var. asigmata, id., 1908, p. 26, p1. iii, fig. 1; Myxilla spongiosa, var. asigmata, id., 1913, p. 625, pl. iii, fig. 3; Hentschel, 1914, p. 99.

 

Occurrence. St. 145: off South Georgia, 26-35 m.

 

REMARKS. Of the specimens hitherto recorded the majority have been encrusting or massive but spreading. That described by Topsent (1913) was, however, pyriform and slightly pedunculate. In all the surface is slightly conulose. The present specimen therefore appears to correspond fairly closely with that described by Topsent (loc. cit.), but is more complete and better preserved than any yet recorded. It is pyriform and pedunculate, 70 mm. high, and 60 mm. by 25 mm. across the top. Several small oscules are situated on the upper surface. The general surface of the sponge is even, glistening when removed from the alcohol, and very minutely conulose.

 

The dimensions of the spicules are the smallest on record. Those of the previously described specimens range as follows: styli 0.495—0.9 by 0.02—0.028 mm., tornota 0.285—0.4 by 0.007—0.01 mm., chelae 0.04—0.075 mm. Those of the present specimen are: styli 0.3 by 0.009 mm., tornota 0.18 by 0.006 mm., chelae 0.03-0.063 mm. The most noticeable feature of this variation in spicule size is that although the two categories of megascleres vary considerably in size, the chelae are almost constant. This holds true for most species of sponges, that while the microscleres may be almost constant in size, the megascleres may be subject to very large ranges of variation.

 

DISTRIBUTION. Graham Land; Victoria Land; Wilhelm Land.”

 

(Burton, 1930)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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