Acarnidae Dendy, 1922

Łukowiak, Magdalena, 2015, Late Eocene siliceous sponge fauna of southern Australia: reconstruction based on loose spicules record, Zootaxa 3917 (1), pp. 1-65 : 36-37

Family Acarnidae Dendy, 1922

There are also extremely rare cladotylotes found in the studied material. Even though the fragment of the cladotylote (the pointed end) is absent (see Fig. 21 N), the size and the morphology of the rest of the spicule suggest that it most probably belongs to the poecilosclerid genus Acarnus Gray, 1867a . There are 6 species of this cosmopolitan genus currently known in Australian waters: Acarnus bergquistae van Soest, Hooper & Hiemstra, 1991, A. guentheri ( Dendy, 1896) , A. hoshinoi van Soest, Hooper & Hiemstra, 1991, A. tenuis Dendy, 1896 , A. ternatus Ridley, 1884 , and A. wolffgangi Keller, 1889 (Atlas of Living Australia) so it is most probable is that they belong to one of these species. The spicules described here may belong to A. ternatus as they possess very similar cladotyles (compare with van Soest et al. 1991, pl. 3, fig. 6) but a certain assignment is not possible because other species of Acarnus (e.g., A. hoshinoi ) also have similar spicules. Acarnus is noted today from temperate and tropical seas, including Australia (Atlas of Living Australia), in predominantly shallow waters (Hooper 2002a).

The articulated spicules of this genus were already recorded from the Miocene of Blake-Bahama Basin (western Central Atlantic) by Bukry (1978, pl. 10, fig. 8).

Figures

FIGURE 21. Spicules of sponges of the order Poecilosclerida; A, B—Punctated oxeas of Histodermella australis Dendy, 1924, family Coelosphaeridae; C, D—Acanthoxeas of Histodermella sp., family Coelosphaeridae; E – H—Different types of acantooxeas of the order Poecilosclerida; I—Isochelae microsclere of the order Poecilosclerida; J, K—Sigma microscleres of the order Poecilosclerida; L, M—Tylotes of the order Poecilosclerida; N—Cladotylote of Acarnus sp., family Acarnidae (not complete); O—Triod of Trikentrion flabelliforme, family Raspailiidae.