Suborder Spongillina subord. nov.: Freshwater Sponges

Abstract

Spongillina subord. nov. (Demospongiae, Haplosclerida) consists of seven families of exclusively freshwater sponges together containing 45 genera: Spongillidae (21 valid genera), Lubomirskiidae (three genera), Malawispongiidae fam. nov. (five genera), Metaniidae (five genera), Metschnikowiidae (monogeneric), Palaeospongillidae (monogeneric), Potamolepidae (six genera), some geographically widespread and others highly endemic. A central body cavity is peculiar to Malawispongiidae. Skeletal network is typically multi spicular alveolate-reticulate with scanty spongin in Metaniidae, Potamolepidae and Malawispongiidae, paucispicular irregularly reticulate in Palaeospongillidae, Spongillidae, Metschnikowiidae with a variable amount of spongin, multi-to paucispicular irregularly reticulate with an abundant amount of spongin in Lubomirskiidae. Smooth or variably ornamented megascleres range from oxeas to strongyles in Spongillidae, Lubomirskiidae and Metaniidae, but are exclusively oxeas in Malawispongiidae, Metschnikowiidae, Palaeospongillidae, and exclusively strongy1es in Potamolepidae. Microscleres usually present in Spongillidae, Palaeospongillidae and Metaniidae, are rare in Potamolepidae, and absent in Lubomirskiidae, Malawispongiidae and Metschnikowiidae. Microscleres if present are oxeas, strongy1es, aster-like, pseudobirotules. Larvae are always parenchymella. Gemmules are typical of Spongillidae, Metaniidae, Palaeospongillidae, rare and strictly adhering to the substratum in Potamolepidae, and absent in Lubomirskiidae, Malawispongiidae and Metschnikowiidae. Gemmular theca is monolayered in Potamolepidae, mono-, bi-or tri-layered in Spongillidae, generally tri-layered in Metaniidae. Gemrnu1es usually armed by gemrnuloscleres in Metaniidae, Potamo1epidae and Spongillidae, are rarely naked in the latter. Gemrnuloscleres are boletiform (tubelliform), parmuliform, pseudobirotules in Metaniidae, and oxeas, strongyles, birotules, pseudobirotules, club-like, botryoidal in Spongillidae. Three more genera incertae sedis are included. This work is a relatively critical synthesis of the literature, however, a critical phylogenetic revision of established taxa is still in progress. . (5) Tubelliform-boletiform gemmulosclere, typical of Acalle and Metania, is characterised by a proximal large, irregularly circular, flat rotule with the entire margin supporting a smooth shaft decreasing in thickness toward the distal apex, and shaped as umbonate pseudo-rotule with large hooks bearing microspines at their apices.Keys to families and genera are primarily constructed for specimens that contain all specific characters, and hence care must be taken when using these for taxa that are 'reduced', or in a non-reproductive 'resting stage'. For example, specimens collected during seasons when gemmules are not produced might be identified as incertae sedis, or as one of the genera that do not produce gemmules. When gemmules are present their associated spiculation is often important to the systematics of Spongillina. Among Potamolepidae...

First report on chitinous holdfast in sponges (Porifera)

“…The diameter of branches varies from 1 to 4 cm ranging from cylindrical to flattened shapes. The colour of live specimens is brilliant green, which is due to the symbionts inhabiting the external layer of sponges [25]. Ectosomal skeleton consists of spicule tufts from primary spongin fibres.…”

A note on five freshwater sponges (Porifera: Spongillina: Spongillidae) from Pune, Maharashtra, India

“…Manconi & Pronzato (2002) have summarised 15 species under this genus. Osborn et al (2008) have described a new species, Radiospongilla pedderensis from Pedder Lake, Tasmania.…”

“…Osborn et al (2008) have described a new species, Radiospongilla pedderensis from Pedder Lake, Tasmania. Six species have been reported from India: R. cantonensis (Gee, 1929); R. cinerea (Carter, 1849); R. crateriformis (Potts, 1882); R. hemephydatia (Annandale, 1909); R. indica (Annandale, 1907); and R. cerebellata (Annandale 1911;Penney & Racek 1968;Soota 1991;Manconi & Pronzato 2002).…”

“…Over 83% of species belong to Class Demospongiae, of which the vast majority are marine although there are many species of freshwater sponges (see van Soest et al 2012, for a detailed overview). All freshwater sponges are now grouped under suborder Spongillina (Manconi & Pronzato 2002) of the order Haplosclerida, and this suborder includes 44 genera classified under six families of extant sponges, of which the Oriental Region possesses 11 genera and 37 species belonging to two families, namely Spongillidae and Metaniidae (Manconi & Pronzato 2008). The suborder Spongillina has been defined by Manconi & Pronzato (2002) as containing exclusively freshwater sponges that possess megascleres-oxeas or strongyles-that are smooth or spined, forming paucito multi-spicular tracts producing, irregular to regular meshes, occasionally with large alveolate cavities; where spongin material is mostly sparse; microscleres present or absent, including smooth or spined oxeas, aster-like or birotule like spicules.…”

“…Only four families produce gemmules or resting bodies that contain totipotent cells enclosed in protective cover. These gemmules, which allow the sponges to survive desiccation, often contain special spicules or gemmuloscleres of diverse morphology that are used in identification of species (see Manconi & Pronzato 2002, for a detailed review and keys to the families / genera of freshwater sponges). Both body and gemmule spicules as well as gemmule morphology are thus important structures and need attention.…”