A Parasite of Marine Rotifers: A New Lineage of Dinokaryotic Dinoflagellates (Dinophyceae)

Dinoflagellate infections have been reported for different protistan and animal hosts. We report, for the first time, the association between a dinoflagellate parasite and a rotifer host, tentativelySynchaetasp. (Rotifera), collected from the port of Valencia, NW Mediterranean Sea. The rotifer contained a sporangium with 100–200 thecate dinospores that develop synchronically through palintomic sporogenesis. This undescribed dinoflagellate forms a new and divergent fast-evolved lineage that branches among the dinokaryotic dinoflagellates.

Marine rotifers from the Northern Adriatic Sea, with description of Lecane insulaconae sp. nov. (Rotifera: Monogononta: Lecanidae)

During a survey of the marine rotifers of the Northern Adriatic Sea, Italy, we found a total of 20 taxa, including a new species of Lecane. This novelty, Lecane insulaconae sp. nov., occurred in the interstitial area of sandy sediment in the outlet of the Isonzo River, at a salinity of 30‰ and is therefore the first exclusively marine representative of this diverse (~200 species) genus. It is characterized by unique sets of anterolateral projections on the ventral and dorsal lorica. Here, we present the description of the species, together with scanning electron microscopy pictures of trophi of this and some other species, and an account of the marine rotifers encountered during the survey.

Rotifers in saltwater environments, re-evaluation of an inconspicuous taxon

Rotifers are microscopic aquatic animals that comprise more than 1800 species. Most rotifer species live in freshwater and limno-terrestrial habitats, while thalassic environments (brackish+seawater) are thought to host few species. No recent review of saline rotifers is available. Here we report the results of a review of the literature concerning rotifers from saline environments, distinguished into three categories: stenohaline, euryhaline, and haloxenous, and found both in truly marine habitats and/or in inland saline waters. A total of about 200 studies, mentioning fully identified rotifers from saline waters, allowed us to list as many as 443 rotifer taxa at either specific, subspecific and infrasubspecific rank, corresponding to 391 nominal species. Truly thalassic taxa, not found in inland saline waters only, accounted for 289, including the ‘stenohaline’ (143) and the euryhaline (146) ones. As for freshwaters, the majority of the thalassic rotifers inhabit the psammon, or display a benthic–periphytic way of life, while the plankton likewise is less species rich and less abundant. The geographical distribution of the brackish and marine rotifers largely reflects the distribution of rotifer investigators, therefore, no biogeographical analysis can be performed yet. In conclusion, the analysis of literature citing rotifers in salt waters, uncovers an unexpected rotifer fauna: the apparent richness of the group in thalassic environments is worthy of being addressed by further investigations, as many species have been reported only by their description, suggesting either considerable endemism or taxonomic errors.