Spongillida Manconi & Pronzato 2002

Order Spongillida Manconi & Pronzato, 2002

We formally accept the new taxonomic status (rank elevation) of the previous suborder Spongillina as the new order Spongillida. The definition and diagnosis (emended after Manconi & Pronzato 2002: 921– 922 and Manconi & Pronzato 2011: 348) are here confirmed in part; we simply erase “ Haplosclerida with” from the beginning of the diagnosis; we add strongyles among megascleres, and we anticipate the presence of the earliest fossil of the taxon at the Upper Carboniferous. We also add a final sentence which states: “The order Spongillida is cosmopolitan in freshwater and brackish water and it is absent only from Antarctica.”

The rank elevation of the suborder Spongillina to the order Spongillida was proposed by Cárdenas et al. (2012) and Morrow & Cárdenas (2015), confirming the monophyly of freshwater sponges on the basis of both morphological (Manconi & Pronzato 2002, 2011) and molecular analyses (Itskovich et al. 1999, 2007, 2008; Addis & Peterson 2005; Meixner et al. 2007; Redmond et al. 2007; Morrow et al. 2012; Morrow & Cárdenas 2015).

Summarizing, from a morphological point of view, Spongillida are characterised by a skeletal architecture of monaxonid spicules (oxeas, styles, and strongyles) organized in isotropic/anisotropic networks of mono- to multi-spicular fibres, with scanty to abundant spongin. Microscleres are often present. Megascleres present as smooth, tubercled to variably spiny monaxons. The presence of resting bodies named gemmules is a trait shared by most families, genera, and species (ca 89%). Gemmules are a key diagnostic trait at genus and species levels. The closest taxon is the marine order Haplosclerida.