Raspailiidae Nardo, 1833

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

Family Raspailiidae Nardo, 1833

Among poecilosclerid spicules one very characteristic spicule can be undoubtedly assigned to the Recent raspailiid genus Trikentrion Ehlers, 1870 ( Fig. 21 O). This triod with one longer, slightly sculptured, about 200 µm long acanthose clad is identical (both in morphology and size) with the spicules occurring in the Recent raspailiids. It most probably belong to the species Trikentrion flabelliforme Hentschel, 1912 (compare with Fig. 22 B) that currently inhabits shallow Australian waters ( Hooper & Wiedenmayer 1994). The other three species of Trikentrion are known from West Africa ( Ehlers 1870), Gulf of California ( Dickinson 1945), and Indonesia ( Carter 1882; Hallmann 1914; Hooper 1991). Other spicules that occur in this species—style megascleres of two size categories and choanosomal oxeas—are not characteristic enough to distinguish them from other studied monaxial spicules. There is also another, very similar, sister genus within the family Raspailiidae— Cyamon Gray, 1867a that has spicules of very similar morphology but contrary to Trikentrion , triacts (or diacts) of Cyamon have all, or at least more than one, clads acanthose; thus, the Eocene spicules undoubtedly belong to Trikentrion flabelliforme .

The species Trikentrion flabelliforme was not reported from the fossil record so far.

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.

FIGURE 22. Spicules of recent peocilosclerid sponges; A—Punctated oxea of Histodermella australis (after van Soest 2002); B—Acanthorhasbds of Rhabdeurypon spinosum (after Hooper 2002 b); C—Triod of Trikentrion flabelliforme (after Hooper 2002 b); D—Acanthorhabds of Crellastrina alecto (from van Soest 2002 b after Topsent 1904).