Morphology, Infraciliature and Phylogenetic Analysis of A new Tintinnid Ciliate (Ciliophora, Choreotrichia) From the Coastal Lake Faro (Sicily, Italy)

A new planktonic tintinnid ciliate of the genus Tintinnopsis, found in the meromictic coastal Lake Faro (Sicily, Italy), is described from both living cells and quantitative protargol-stained preparations. The sequence of the small subunit rRNA (SSU rRNA) gene is also reported. Loricae of this species are composed of a subcylindrical bowl, featuring a fine mesh of hexagonal structures, with sparse biogenic matter adhering on the chitinous basal layer, and of a branched aboral horn, characterized by an alveolated texture. The lorica length and oral diameter ranges are respectively 152–205 μm and 33–44 μm. Fully extended living cells are elongate obconical, 107 to 144 μm in total length and 28 to 38 μm in maximum width. Two ellipsoidal macronuclei are always present. The somatic ciliary pattern of this species comprises a ventral, a dorsal, and a posterior kinety as well as right, left, and lateral ciliary fields. Loricae of Tintinnopsis n. sp. are similar to those of Tintinnopsis (Paratintinnopsis) corniger (Hada, 1964) in their overall shape and in the aboral horn texture. Important differences, however, lay in the presence of 12-15 spiral turns at the oral end and in the scarce agglomeration of foreign particles in Tintinnopsis n. sp., the latter character contrasting with the typical traits of the genus. The phylogenetic analysis of this new species, based on the SSU rRNA gene, shows it to group with other Tintinnopsis species, but at a basal level in this clade.