Loricophrya sivertseni ( Allgén, 1951 )

Loricophrya sivertseni ( Allgén, 1951) View in CoL

( Fig. 2A–L View FIGURE 2 )

Ciliate specimens were found attached on nematode host belong to the genus Desmocolex , from stations: MUC-8 (191 m depth), MUC-9 (203 m depth); on basibiont Quadricoma sp. from MUC-9 (203 m depth), MUC-12 (915 m depth); on basibiont Desmoderella sp. from MUC-12 (915 m depth).

The found organism is a suctorian ciliate with elongate weakly laterally flattened cell body covered by lorica (stylotheca). The cell body attached to stylotheca at its aperture and fills nothing more than half of lorica volume. Stylotheca cone-shaped, weakly laterally flattened. The clefts of aperture rim are feebly marked. Pseudostyle short, non-transparent, narrowed downwards. Five to ten capitate, flexible tentacles occupied the apical surface of the cell body. Macronucleus ovoid, centrally located. Measurements from present find (in µm, based on 7 individuals): Stylotheca length 33–56; width 15–19; thickness 12–13; pseudostyle length 4–11; diameter 2–5; body length 11–41; width 6–17; thickness 9–10; macronucleus length 9–10; width 4–9; tentacle length 3–16.

The species Loricophrya sivertseni was found and described (as Thecacineta sivertseni ) by Allgén (1951) as epibiont of nematode Spirina parasitifera , collected at cost of Islant Tautra, Trondheimsfjord, Norway ( Allgén 1951; Curds 1987). The author ( Allgén 1951) has emphasized the characteristic elongate lorica with scalloped rim in the species. Later Matthes (1956) transferred the species into genus Loricophrya . In Indian Ocean Loricophrya sivertseni was reported at 21 m depth from coral reef of North Malé atoll, Archipelago of Maldives as epibiont on nematode belongs to Paradesmodora after cloacal opening of the basibiont ( Baldrighi et al. 2020). It was also mentioned that L. sivertseni and L. stresemanni were found as epibionts on the same specimen of Paradesmodora . In Allgén’s (1951) diagnosis L. sivertseni is a large (108 µm long) suctorian species, while in our materials the dimentions of individuals were about half as mentioned above.

It should be mentioned that L. sivertseni is enough similar to L. bosporica Sergeeva & Dovgal, 2016 , which also found on nematode hosts ( Sergeeva & Dovgal 2016; Chatterjee et al. 2022). However, in differ from L. sivertseni , the lower part of stylotheca in L. bosporica separated from the upper part by a well-visible septum, have a basal disc, the clefts at rim of aperture are also absent. The stylotheca characterized by a gradual thickening of the walls toward the aperture ( Sergeeva & Dovgal 2016). Just another relative species, L. stresemanni ( Allgén, 1951) differs from L. sivertseni by presence of well developed, transversally striated pseudostyle of lorica, smooth rim of the lorica aperture and by elongate cell body, which can significantly protrude from the edge of the lorica ( Allgén 1951; Curds 1987; Chatterjee et al. 2019).