Epistylis plicatilis Ehrenberg, 1831

Utz, Laura R. P., 2007, First record of Epistylis plicatilis (Ciliophora: Peritrichia) attached to Pomacea canaliculata (Mollusca: Gastropoda) in Southern Brazil, Zootaxa 1454 (1), pp. 49-57 : 52-53

Epistylis plicatilis Ehrenberg, 1831

Morphology of live specimens: Colonies were dichotomously branched with alternate branches terminating approximately at the same level ( Fig. 2 ). Neither the main stalk nor its branches were contractile. The main basal stalk was short, with a smooth surface, without protuberances or ridges. Primary branches were the longest in the colony, and similar in width to the main stalk with no difference found between collection sites ( Table 1). Colonies had up to 100 zooids, but usually consisted of 10–20 zooids that were similar in size. Zooids were elongate and ranged from 105.0 to 187.5 µm in length and from 25.0 to 52.5 µm in width ( Table 1, Fig. 2 ). When contracted, the zooid was transversely folded in the region near to the scopula ( Fig. 3 ). The peristomial lip was wider than the body and folded transversally in the fully extended zooid ( Fig. 4 ). It also presented a snout-like protuberance when the zooid was contracted ( Fig. 3 ). The epistomial disk was highly elevated, and was ~ ¾ as wide as the peristomial lip. A single “C-shaped” macronucleus was observed in the oral half of the cell, lying transversely below the peristomial lip ( Fig. 4 ).

Morphology of stained specimens: Infraciliary and nuclear characteristics of E. plicatilis were easily recognized in protargol stained colonies. A total of 22 somatic myonemes extended from the scopula to the epistomial disk of the zooid ( Fig. 5 ). In the trochal band, only one row of kinetosomes was present ( Fig. 6 ). A spherical micronucleus was located close to the C-shaped macronucleus ( Figs. 7 and 8 ). The oral infraciliature is typical of sessile peritrichs and presents an outer haplokinety and an inner polykinety (PK1) that describes approximately 1 ½ turns around the peristomial disk before entering the infundibulum ( Figs. 8 and 9a ). In addition to PK1, the infundibular polykineties PK2 and PK3 were also identified ( Figs. 8 and 9b ): PK1 consisted of three rows of kinetosomes equal in length. PK2 also presents three rows of kinetosomes equal in length that terminate at the adstomal curvature of PK1; only a narrow gap existed between PK1 and PK2. PK3 consists of three short rows of kinetosomes that lie in a right angle to PK2 ( Figs. 8 and 9b ). PK3 terminates adstomally, close to the adstomal end of PK2.

Figures

FIGURE 9. Drawings of the oral polykinetids (OPKs) of Epistylis plicatilis. A. Profile of the OPKs. B. Detail of OPKs inside the infundibulum. Bar = 1 µm.

FIGURES 1–4. 1. Colonies of Epistylis plicatilis attached to Pomacea canaliculata. Bar = 2 mm. 2. Overall shape of a colony of E. plicatilis. Bar = 500 µm. 3. A contracted zooid showing a transversely folded region near the scopula (arrow) and a snout like protuberance in the peristomial region (arrow head). Bar = 150 µm. 4. A distended zooid showing the macronucleus (arrow). Bar = 150 µm.

FIGURES 5–8. 5. Protargol stained zooid showing somatic myonemes (arrow head). 6. A stained zooid showing the single row of kinetosomes in the trochal band (arrow head). 7. A single micronucleus inside the zooid (arrow head). 8. Detail of oral polykinetids 1 (PK1), 2 (PK2), 3 (PK3), and the “C” shaped macronucleus (arrow). All bars represent 25 µm.