Renata Manconi

Suborder Spongillina subord. nov.: Freshwater Sponges

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 multispicular 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 strongyles 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, strongyles, 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. Gemmules usually armed by gemmuloscleres in Metaniidae, Potamolepidae and Spongillidae, are rarely naked in the latter. Gemmuloscleres 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.

The marine sponge Chondrilla nucula Schmidt, 1862 as an elective candidate for bioremediation in integrated aquaculture.

The use of sponges for marine bioremediation in a farming scenario has been investigated focusing on Chondrilla nucula. We report experiments examining clearance and retention rates of the bacterium Escherichia coli. Despite low values expressed for clearance tests, C. nucula exhibited a marked ability to retain high quantities of bacteria. One square meter patch of this sponge can filter up to 14 l/h of sea water retaining up to 7 x 10(10) bacterial cells/h. This suggests that C. nucula is a suitable species for marine environmental bioremediation.

Global diversity of sponges (Porifera: Spongillina) in freshwater

Porifera is a primarily marine phylum comprising more than 15,000 species. The successful and wide adaptive radiation of freshwater sponges (Haplosclerida: Spongillina) has resulted in the colonization of an extremely wide variety of habitats at all latitudes. Colonization is dated back to the Mesozoic, and the mono- or poly-phyletism of Spongillina, and the number of potential sponge invasions into freshwater is still under debate. Living freshwater sponges belong to 45 genera in six families for a total of 219 species. The highest diversity, at the scale of zoogeographic regions, is recorded from the Neotropical (65 species), Palaearctic (59 species), and Afrotropical regions (49 species). Endemic freshwater sponge species are 103 (47%) out of 219. All species belonging to the families Lubomirskiidae, Metschnikowiidae, and Malawispongiidae are endemic. Endemic species among the other families are 72% for Potamolepidae, 38% for Spongillidae, and 32% for Metaniidae. Data on some wide geographic areas are scattered and fragmentary if not almost completely lacking. Species richness is probably underestimated and doubtless destined to increase with further research.

Life cycle of Spongilla lacustris (Porifera, Spongillidae): a cue for environment-dependent phenotype

We studied the life cycle and growth of Spongilla lacustris in a stream with three distinct habitats. Sponge populations in the habitats exhibited different adaptive strategies. Growth forms of S. lacustris ranged from encrusting to digitate and branched. Environmental factors controlled the appearance of each growth form. In the most hospitable habitat, a variety of colonization strategies and different growth forms were present. In the less hospitable habitat growth was restricted to small and encrusting specimens. In the optimal habitat, the largest and most luxuriant specimens developed. Gemmulation and hatching were dephased among specimens in the three habitats; hence gemmules were present for long periods of time. S. lacustris was found capable of displaying two life strategies: r in the short run, K in the long run.

BIORHYTHM AND ENVIRONMENTAL CONTROL IN THE LIFE HISTORY OF EPHYDATIA FLUVIATILIS (DEMOSPONGIAE, SPONGILLIDAE)

Abstract The life cycle of Ephydatia fluviatilis involves obligatory gemmule formation, a process strongly related to environmental conditions. A comparative investigation carried out on three populations of this species distributed along a climatic gradient, besides confirming a link between occurrence of gemmules and the severity of the habitat, evidences that gemmulation may be triggered even by endogenous stimuli. Indeed, in the northern area (Torrente Scrivia, Liguria), subjected to ice‐up and notable thermic and water‐flow fluctuations, the sponges hibernate for a long period and show shorter summer activity. In the southern area (Canale Tagliavla, Sicily), with a summer dry‐up, the active sponges are present during the winter, while the quiescence coincides with an aestivation. The persistence of this rhythm over the years is discussed, also in consideration of a speciation trend which points to a physiological reproductive barrier between these metapopulations. By contrast, in the intermediate are...

African planarians: Dugesia aethiopica sp. n. (Platyhelminthes, Tricladida) from Lake Tana (NW Ethiopia)

Abstract A new species of Dugesia from East Africa is described as a first report of Platyhelminthes from Lake Tana. Dugesia aethiopica sp. n. is characterized by the shape of its bursa copulatrix; length, diameter, course, and opening of the bursal canal; opening of the oviducts; shape of the penis papilla; penial parenchymatic cavity. The taxonomic position of the new species within the D. gonocephala group is discussed in comparison with the other African and Madagascan species.

Rediscovery of the type material of Spongilla lacustris (L., 1759) in the Linnean herbarium

Abstract The type material of Spongilla lacustris, recently found in the Linnean herbarium, is described. Type locality and present distribution are shown. Morphological diagnostic traits are described by SEM microphotography. This is the single species of Porifera out of 12 described by Linnaeus in 1759, with type specimen known. A lectotype is selected from two syntypes.

Metabotropic γ-aminobutyric acid (GABAB) receptors modulate feeding behavior in the calcisponge Leucandra aspera

Here, we report the presence of the γ-aminobutyric acid (GABA)-ergic system in the calcisponge Leucandra aspera and examine the cellular localization of the components of this system, including GABA-like receptors using immunofluorescence and confocal microscopy. Furthermore, we demonstrate for the first time that GABA plays a functional role as a messenger in regulating sponge-feeding behavior. We found that both GABA(B) R1 and R2 subunits are present in the choanocytes of sponges as well as in the eso- and endopinacocytes. The functional role of GABA in the feeding behavior of this sponge was tested. The involvement of GABA receptors in the endocytic processes in L. aspera was demonstrated with dextran conjugated to Texas Red as a marker for material ingestion and by treating isolated sponge cells with a GABA(B) receptor agonist and an antagonist. The amount of dextran that was ingested increased in dissociated sponge cells when the GABA(B) receptor agonist baclofen was used, and this stimulatory effect was prevented by treatment with the GABA(B) receptor antagonist phaclofen. The baclofen effect on uptake was blocked by treatment with pertussis toxin, thus indicating a role for G proteins in modulating feeding behavior in L. aspera. Moreover, we found evidence that GABA receptors are involved in the consumption of dissolved organic matter by sponge cells. These findings suggest that GABA receptors and their functional role are highly conservative traits in the animal kingdom prenervous system evolution.

Adaptive strategies of sponges in inland waters

Abstract The notable plasticity of Porifera allowed the colonization of inland waters during the Mesozoic Era as a consequence of the gradual morpho‐functional adaptations of dormant bodies, i.e., the appearance of the pneumatic coat and of spiny spicules, which could be responsible for the realization of an overland dispersal. The gem‐mule, with its high potentialities as an adaptive device, is the key structure in understanding the life history and the evolution of Spongillidae. The other two families of freshwater sponges, Potamolepidae and Lubomirskidae, do not have a widespread diffusion, probably because of the absence of specialized resistent bodies, such as gemmules, able to act as propagules. In spite of the ability to produce gemmules, few species of spongillids are cosmopolitan; Ephydatia fluviatilis shows the highest plasticity, adapting its life cycle to different climatic conditions: hibernant and aestivant populations live, respectively, in cold‐humid and warm‐arid climates. The persistent ...

Sponges of marine caves: Notes on the status of the Mediterranean palaeoendemic Petrobiona massiliana (Porifera: Calcarea: Lithonida) with new records from Sardinia

The discovery of conspicuous populations of the rare species Petrobiona massiliana is reported from shallow water karstic caves of Sardinia. The morphological comparative analysis versus previous data from the entire geographic range highlights that spicular traits seem to be highly conservative in contrast with a notable plasticity of growth form. Lifestyle and adaptive strategies that favoured the successful spread of P. massiliana in karstic caves and its persistence as extremely isolated populations in a fragmented habitat are discussed together with potential environmental constraints. The data indicate that conservation of this Mediterranean palaeoendemic species with a spot‐like distribution may be a challenge for the western Mediterranean Marine Protected Areas to confer protection to numerous co‐occurring cave‐dwelling species.