REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 99 



Heterorotula nigra (Lendeufeld, 1887) 



Plate 8, figures 2, 6, 9 



Ttibella nigra Lendenfeld, 1887, p. 91.— Whitelegge, 1889, p. 306.— Weltner, 



1895, p. 128; 1910, p. 137.— Gee, 1931d, p. 28. 

 Ephydatia nigra Gee, 1931e, p. 44; 1931d, p. 56; 1932c, p. 32. 

 Meyenia nigra Penney, 1960, p. 53. 



Material. — Slides of type (AusM) and syntype (N. Gist Gee) ; 

 material and slides from Australia (Racek). 



Description. — Sponge usually forming flat encrustations on 

 aquatic plants, when occurring on reeds or timber often massive; 

 smface comparatively even and smooth, rarely slightly lobose; 

 oscula few and inconspicuous; dermal membrane well developed, 

 closely adhering to symplasm. Skeleton consisting of ill-defined and 

 very slender spicule fibers, coated together by only small amounts 

 of spongin. Consistency of live sponge moderately soft and very 

 fragile. 



Megascleres slender and fusiform amphioxea, in the majority 

 entirely smooth, occasionally covered with a small number of incon- 

 spicuous spines except at their tips; length range 224-360 /i, width 

 range 7-13 /x. 



Microscleres absent. 



Gemmoscleres birotulates with a very slender, finely granulated 

 shaft, and terminally with flat rotules of unequal diameter; faces 

 of rotules smooth; margin of rotules regularly or irregularly incised 

 to form distinct teeth; length differences of birotulates very pronounced; 

 length range of larger series 56-73 n, of smaller 35-48 n; wddth range of 

 lower rotule 13-16 ix, of upper 10-14 n; thickness of shaft 2-4 At. 



Gemmules spherical and moderately large, scattered in basal parts 

 of sponge, almost at its base in small encrusting forms, diameter 

 ranging 230-360 m; pneumatic layer well developed and irregular, 

 but never higher than the longest gemmoscleres ; consisting of minute 

 spherical air spaces; gemmoscleres embedded in this layer strictly 

 radiaUy, with theu- large rotules firmly inserted in the inner gemmular 

 membrane; reinforcement of pneumatic coat by megascleres absent; 

 outer gemmular membrane distinctly corrugated, and almost white; 

 foramen simple or bearing a very shallow peripheral collar. 



Distribution. — Apparently restricted to swampy areas of eastern 

 Australia. 



Color in life. — Light to dark brown, rarely dark gray to black 

 due to presence of mud particles in the symplasm. 



Discussion. — This species represents the other extreme in the 

 intergrading series of gemmosclere characters. Although more than 



279-430—68 9 



