Notohymena australis (Foissner and O'Donoghue, 1990) Berger, 1999

Hu, Xiaozhong & Kusuoka, Yasushi, 2015, Two Oxytrichids from the Ancient Lake Biwa, Japan, with Notes on Morphogenesis of Notohymena australis (Ciliophora, Sporadotrichida), Acta Protozoologica 54 (2), pp. 107-122 : 120-121

Comparison of Notohymena australis with previous descriptions

Our form corresponds well with the type population of Notohymena australis in body shape, color and arrangement of cortical granules, ventral and dorsal ciliature, especially the number of adoral membranelles, and the presence of a bipolar dorsal kinety 3 and multi- ple caudal cirri in three rows; therefore, both are judged to be conspecific. Morphometric comparisons should be made between the present isolate and the other two populations. The body size of the present population of Notohymena australis is outside the range reported in the original description, which was 65–95 × 22–29 μm for fixed specimens ( Foissner and O’Donoghue 1990; Berger 1999), but close to that of the German population studied by Foissner and Gschwind (1998), which measured 108–160 × 42–72 μm. The numbers of left and right marginal cirri of the current population are within the range of both earlier populations (24–44 LMC, 24–40 RMC). All these facts suggest a continu- ous variation in body size and number of marginal cirri among populations. The Australian population has a variable number of postoral and pretransverse ventral cirri ( Foissner and O’Donoghue 1990; Berger 1999), by contrast, this value varies less in the Japanese population (total number of ventral cirri: min = 5, max = 6, mean = 5.1, CV = 4.3%, n = 20).

Data on morphogenesis are available for four species in the genus, which confirms two differences among them. Notohymena australis is more similar to N. apoaustralis than to N. rubescens and N. saprai ( Blatterer and Foissner 1988; Lv et al. 2013; Kamra and Kumar 2010). In the former two species, the new oral primordium originates to the left of the postoral ventral cirri and more than two caudal cirri are formed at posterior end of each anlage of dorsal kineties 1, 2, and 4. In the latter two species, however, oral primordium appears to the left of the leftmost transverse cirrus, and only one caudal cirrus is evolved from each of the mentioned dorsal kinety anlagen. Minor differences between N. australis and N. apoaustralis lie in the mentioned anlagen of marginal rows. As illustrated, these anlagen originate earlier in the former species than in the latter. The left anlagen very likely originate somewhat later than right ones in N. australis , but the same thing was not recorded in the original description of N. apoaustralis .