Using standard methods, we studied the morphology and distribution of an Australian
population of Australocirrus shii (Shi et al., 1997) nov. comb. and a Jamaican population
of A. australis (Foissner, 1995) nov. comb. We identified three features, not or rarely
used earlier, that distinguish Australocirrus shii from A. australis: the distance
between the anterior pretransverse cirrus and the anteriormost transverse cirrus (5-8%
vs. 1.5-1.7% of body length), the arrangement of the transverse cirri (3+2 vs. an
oblique row), and the resting cyst macronuclear nodules (separate vs. fused). Australocirrus
shii has been reported from Asia and Australia while A. australis is possibly restricted
to the Neotropic. Because of problems in getting voucher materials of A. shii, we
emphasise that permanent slides should be deposited in international repositories.
Based on previous studies and new data, especially a refined interpretation of the
shape of the paroral membrane, we suggest synonymy of Cyrtohymenides and Australocirrus.
Thus, Cyrtohymena (Cyrtohymenides) shii, C. (Cyrtohymenides) aspoecki, and C. (Cyrtohymenides)
australis are transferred to Australocirrus which is, inter alia, defined by a moderately
to distinctly curved, but not recurved, paroral membrane, multiple fragmentation of
dorsal kinety 3 and three or more dorsomarginal kineties.