Cothurnia amphicteis, LANG, 1948

Semprucci, Barbara Mikac Federica, Guidi, Loretta, Ponti, Massimo, Abbiati, Marco, Balsamo, Maria & Dovgal, Igor, 2020, Newly discovered associations between peritrich ciliates (Ciliophora: Peritrichia) and scale polychaetes (Annelida: Polynoidae and Sigalionidae) with a review of polychaete-peritrich epibiosis, Zoological Journal of the Linnean Society 188, pp. 939-953 : 941-942

COTHURNIA AMPHICTEIS LANG, 1948

( FIGS 2–4)

Material examined

Light-microscopy measurements based on six Cothurnia specimens found on the polychaete Malmgrenia lilianae , north Adriatic Sea, station SJ107, 21 June 2005. Additional material examined from the polychaete M. lilianae , north Adriatic Sea: station SJ005, 30 August 2005 (three polychaetes), 18 October 2006 (one polychaete); station SJ007, 15 March 2005 (one polychaete; mounted for SEM), 21 June 2005 (two polychaetes), 18 October 2006 (one polychaete), 13 September 2007 (one polychaete); station SJ107, 21 June 2005 (one polychaete; mounted for SEM), 22 December 2005 (two polychaetes), 13 September 2007 (two polychaetes, one mounted for SEM), 12 October 2007 (one polychaete). Additional material examined from the polychaete M. andreapolis , north Adriatic Sea: station SJ005, 22 September 2006 (one polychaete, mounted for SEM); station SJ107, 12 October 2007 (one polychaete).

Description

Lorica conical, smooth, with thin wall, 57–77 μm long (53–56 μm after Warren & Paynter, 1991) × 35 μm wide. Aperture circular 30–33 μm (35–37 μm after Warren & Paynter, 1991) in diameter, the edge of aperture with extremely small, irregular outgrows ( Figs 2C, 4C). External stalk conical, flexed near substrate ( Fig. 4A), with an annular bulge in connection with lorica base and basal disc, 18–35 μm (54–57 μm after Warren & Paynter, 1991) long, with conspicuous transverse folds ( Fig. 4D). Endostyle short, broad, with longitudinal striae that are nor visible in some cases. Mesostyle absent. Generally, two zooids are present ( Figs 2D, 4B). Zooid conical, 85 × 40 μm, and extends between one third and one half of its length beyond aperture ( Fig. 4B). The length of contracted zooids 31–59 μm, width 7–21 μm. Peristomial lip well-developed, 45 μm in diameter. Disc convex. Contractile vacuole lies just below peristome. Macronucleus elongate slightly curved anteriorly. Pellicular striations conspicuous.

Remarks

New specimens differ from the original description of C. amphicteis by the presence of two zooids in the lorica (with one exception) and the greater length of the lorica. Only contracted zooids were measured. The diagnosis of related species C. acuta Levander, 1915 (after Warren & Paynter, 1991) is rather similar to C. amphicteis . In both diagnoses, the absence of a mesostyle was mentioned. However, on Precht’s (1935) picture, C. acuta has the typical mesostyle with longitudinal striae. In our specimens, the mesostyle was absent, thus we consider them C. amphicteis . The suggested synonymy between C. acuta and C. amphicteis needs further consideration. This is the first finding of the species after its original description by Lang (1948).

Habitat

Marine, originally found attached to the chaetae of polychaete Amphicteis gunneri (M. Sars, 1835) (fam. Ampharetidae ) (type host) in coastal waters of Sweden, Baltic Sea (type locality) ( Lang, 1948). Other locality: north Adriatic Sea, on the chaetae of polychaetes Malmgrenia lilianae and M. andreapolis (this paper).