These prokaryotes

are not limited with membranes, instead lying freely in the cytosol, and seem to belong to Gram-negative bacteria (Figure 5C, D, G) due to the two covering membranes (Figure 5D). They are represented by at least two types: long narrow (nlb) and big flagellated bacteria (bfb). The bfb have a set of rather long flagella which are Torin 1 datasheet Tubular in cross section (Figure 5D) and tend to associate with lipid globules (Figure 5D, E, G). Mode of feeding Live observations of both strains revealed a typical Monosiga-type mode of this website feeding [29, 30]. The feeding pseudopodium arises from the top of the neck outside the collar, grows towards the bacterium on the outer surface of the collar and engulfs the prey producing a food vacuole. These observations were confirmed by cross sections through the collar base

(Figure 6B, insert). Additionally, feeding pseudopodia arising from the side of the neck were found for both strains (Figure 6C). This mode of engulfment is typical for Codosiga and some other colonial choanoflagellates with a thin sheath around the cell [29, 30]. The presence of two feeding modes is easily explained by the combination of solitary VS-4718 and colonial life styles for both strains: solitary cells feed in Monosiga-type mode, and colonial cells feed as other colonial choanoflagellates (Codosiga, Desmarella, Sphaeroeca). Formal taxonomic description Codosiga balthica sp. nov. Wylezich et Karpov (Choanoflagellatea (Kent) Cavalier-Smith, 1998, Craspedida Cavalier-Smith, 1997; Salpingoecidae (Kent) Nitsche et al., 2011). Diagnosis: Sedentary stalked solitary cells with rare production of colonies of 2–4 cells. Flask-shaped cell with a broad and short neck surrounded by a delicate sheath, visible through electron microscopy. Dimensions: body length – 3–4.5 μm, width – 2 μm, length of the collar equal to the body, flagellum 2–2.5 times longer than the body, stalk: up to 3 body lengths. Tubular or saccular mitochondrial cristae, intracellular flagellated bacteria present in cytosol not limited with membrane.

Observed habitat: Gotland Deep (central Baltic Sea, IOW station 271, 57°19′N, 20°10′E) suboxic to anoxic water masses (depth 206 m), brackish (8–25 ‰); Type material: iconotypes: Figure 5D, E; fixed and embedded specimens (hapantotypes) ID-8 are deposited at the Oberösterreichische Landesmuseum in Linz, Austria (inventory number 2012/121); live strains (paratypes) are held as clonal cultures (strain IOW94) in the laboratory of the Leibniz Institut for Baltic Sea Research in Rostock-Warnemünde; Etymology: balthica after the Baltic Sea, where the strain was isolated. Closely related clonal sequences were available from Gotland Deep and Framvaren fjord but not from other habitats, oxic or hypoxic. Codosiga minima sp. nov. Wylezich et Karpov (Choanoflagellatea (Kent) Cavalier-Smith, 1998, Craspedida Cavalier-Smith, 1997; Salpingoecidae (Kent) Nitsche et al.