Acineta

Ansari, Kapuli Gani Mohamed Thameemul, Guidi, Loretta, Dovgal, Igor, Balsamo, Maria & Semprucci, Federica, 2017, Some epibiont suctorian ciliates from meiofaunal organisms of Maldivian archipelago with description of a new ciliate species, Zootaxa 4258 (4), pp. 375-387 : 384

Acineta sp.

( Figs. 7 a, b)

Diagnosis. Marine suctorian ciliate. Trapezium-like cell body, weakly laterally compressed, thin-walled and wrinkled. Lorica filled with cell body and provided with a dumb-bell shaped apical aperture. Two lobe-like actinophores protruding. Usually tentacles arranged in two fascicles in the apical aperture. Small solid stalk. Reproduction by mono- or polygemmic internal budding.

Morphological description. Marine loricate suctorian. Cell body trapezium-like, weakly laterally compressed and fully covered with lorica. Insertion of lorica at the body base. Thin-walled lorica about 52 µm in length and 21 µm in width, ratio of length to width approximately 2:1, maximum width at the upper end ( Figs. 7 a–b). Very minute longitudinal rows across the lorica. Apical aperture dumb-bell shaped showing two protruding lobe-like actinophores. Tentacles not visible at the apical region ( Figs. 7 a–b). Very small solid stalk, slightly apically extended. Stalk length 3 µm and thickness 1µm. The usually monogemmic or polygemmic internal budding and swarmers were not observed.

Remarks. The studied specimen of Acineta sp. was similar to the type species Acineta tuberosa Ehrenberg, 1834 due to the Y-shaped outline and the stalk joining lorica without any basal disc but differed in the stalk length and the basibionts. On other side, it also showed similarity with Acineta laevis Dons, 1918 from red algae, with body fully covered by lorica and permanently contracted tentacles. However Acineta sp. differs from A. laevis by a relatively thin stalk, 1 µm, vs. 8 µm (see Curds 1985).

Host specificity and locality information. Acineta sp. adhered to a free-living marine nematode species, Croconema cinctum , and it was collected from sediments mainly characterized by sand (93%), followed by gravel (5%) and mud (3%) at a depth of 61 m (S1 station).

Figures

FIGURE 7. Scanning electron microscopy images of Acineta sp. adhering to the nematode Croconema cinctum: a) attached specimen; b) magnification of the specimen.