Askoella Fenchel, 1965

Dovgal, Igor & Mayén-Estrada, Rosaura, 2015, A taxonomic revision of order Pilisuctorida (Ciliophora, Apostomatia) with keys to the subordinate taxa, Zootaxa 4040 (5), pp. 543-558 : 547

Genus Askoella Fenchel, 1965

Fenchel (1965) described new ciliate genus Askoella Fenchel, 1965 with the type species A. janssonі Fenchel, 1965 ( Fig. 2 A–C) from the amphipod crustacean Gammarus oceanicus Segerstråle, 1947 (type host). This ciliate was found on 50% of Gammarus individuals collected near Asko ( Denmark, type locality). In addition A. janssonі has been observed on a specimen of G. locusta (Linnaeus, 1758) from the Oresund strait.

The cell body of A. janssoni is ovoid and flattened. The left rim is more convex than the right one. The ventral side is slightly concave while the dorsal side is convex. There are two kineties on the dorsal side of the body and three kineties on the ventral side. The cytostome is provided by a vestibulum and situated on the anterior third of the ventral body side, to the right of the middle. The macronucleus is large and U-shaped. There is a contractile vacuole situated in the posterior end of body.

Jankowski (1967b) described a second species of the genus, A. heliostoma Jankowski, 1967 ( Fig. 2 D) from acorn barnacle Semibalanus balanoides (Linnaeus, 1767) collected in the Barents Sea near Murmansk, Russia (type locality).

Askoella heliostoma has an oval, small, light coloured body filled with food vacuoles. The apical region of the cell body is tapered, whereas the antapical is provided by a characteristic groove which leads to a long convoluted canal terminating near rosette. The rosette septa are not arranged parallely one to another like in A. janssoni , but there are radially arranged as in the rosette trophonts of Gymnodinioides . Jankowski (1967b) considered this distinctive character to distinguish A. heliostoma from A. janssoni , and Jankowski (1967b, 1972) included some observations of A. helіostoma nutritions and reproductions.

Figures

FIGURE 2. Ciliates of genera Askoella and Ascophrys described by different authors. A—ventral side of Askoella janssoni; B—dorsal side of A. janssoni (scale bar 10 µm); C—macronucleus morphology of A. janssoni; D— A. heliostoma; E—trophont of Ascophrys rodor: F—phoront of Ascophrys rodor (A – C—modified from Fenchel, 1965; D—modified from Jankowski 1967 b; E-F—modified from Deroux, Campillo and Bradbury, 1975).