Thecacineta calix ( Schröder, 1907 ), Schroder, 1907

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 : 380-381

Thecacineta calix ( Schröder, 1907)

( Figs. 5 a–d)

Diagnosis. Marine loricate suctorian. Lorica filled with cell body, transversely ribbed and attached to its base. A fascicle of clavate tentacles in apical surface of body. Macronucleus ovoid with large contractile vacuole. Long and curved stalk with apical widening. Reproduction by vermigemmic budding.

Morphological description. Marine. Cell body fully filling the lorica and attached to its base. Lorica size 50– 81 µm × 22–34 µm, ratio of length to width approximately 2:1, maximum width at the middle ( Figs. 5 a–d). Whole lorica characterized with several annular ridges variable in number from 13 to 24 ( Figs. 5 a–c). Apical surface of the body bearing a fascicle of clavate tentacles, 10–14 µm in length and 1 µm in thickness ( Figs. 5 a and 5c). Macronucleus and micronuclei not observed. Stalk long, thin and curved with apical widening (physon) and base attaching to the host. Stalk 10–17 µm in length and 2.1–2.2 µm in thickness ( Figs. 5 a–d). Reproduction by vermigemmic budding with formation of laterally vermiform protomit ( Fig. 5 d). Swarmer without annular ridges or tentacles.

Remarks. The observed specimens of Thecacineta calix ( Schröder, 1907) differ from those earlier reported by a larger variation in the number of ribbed transverse annular ridges. In the observed specimens the transversely annulated ribs varied from 9 to 26 throughout the body (see Fig. 5 a,b,c). Moreover, the present specimens were two-fold smaller than that found in Mediterranean Sea, which was attached to the harpacticoid copepod Laophonte cornuta ( Matthes, 1956) . They were particularly comparable with those reported by Chatterjee et al. (2014) from Caribbean reef ecosystem.

Host specificity and locality information. T. calix ( Schröder 1907) is well known as a widespread suctorian ciliate attached to numerous groups of interstitial invertebrates such as nematodes and halacarid mites. In particular, it is frequent on the nematodes of the family Desmodoridae ( Schröder 1907; Schulz 1931; Steiner 1931; Allgén 1949; Matthes 1956; Susetiono 2006; Jankowski 2007; Ingole et al. 2010) and Epsilonematidae (e.g. Steiner 1931; Allgén 1955), crustacean copepods ( Matthes 1956; Chatterjee et al. 2014) and halacarid mites ( Gelmboldt & Dovgal 2005; Dovgal et al. 2008a). The specimens recorded in the present study were found on the nematodes Croconema cinctum Cobb, 1920 , and Desmodorella tenuispiculum Allgén, 1928 , and few budding stages were observed on harpacticoid copepods.

In detail, this species was found in Maldives at 61–62 m depth (S1 and S2). Here, lagoon sediments were mainly represented by 93% of sand, 5% of gravel and 3% of mud at S1 and 56% of sand, 0.3 of gravel and 45% of mud at S2.

Figures

FIGURE 5. Scanning electron microscopy and bright field microscopy images of Thecacineta calix (Schröder, 1907) adhering to meiofaunal organisms: a) morpho-type I on Croconema cinctum; b) morpho-type II on Desmodorella tenuispiculum; c) morpho-type II on Desmodorella tenuispiculum; d) budding trophont on harpacticoid copepod.