PROGRESS IN PROTOZOOLOGY

188 B. M. HONIGBERG
tion among different members. One pattern (exemplified by Naegleria)
is characterized by the lobose pseudopodia encountered in amebae
of the subclass Lobosia. Another pattern (exemplified by Dimorpha
and other helioflagellates) is marked by typical axopodia terminating
internally in a central granule or centroplast, as in heliozoa
of the order Centrohelida. Future studies can be expected to lead to
a more natural regrouping of the forms placed here for convenience.""
As might have been expected, the order RHIZOMASTIGIDA was omitted
from the more recent scheme published by L e v i n e et al. (1980). Actually,
the constitution of this "order" has varied among the standard
protozoology texts; e.g., Hall (1953) included the following genera
among RHIZOMASTIGIDA: Histomonas, Heliobodo, Mastigamoeba, Mastigella,
Mastigina and Rhizomastix. Amon other workers, he felt also
that Pteridomonas was a chrysomonad and that Actinomonas and Dimorpha
had helioflagellate affinities. Grasse (1952) thought that Pteridomonas
was also a helioflagellate. Many authors (e.g., Kudo 1966)
included Tetramitus and Naegleria in RHIZOMASTIGIDA. Certain protozoologists
assigned at least some of the rhizomastigid genera to many
flagellate and rhizopod assemblages. Vickerman, who until recently
(Vickerman 1976) considered Cercomonas and Heteromita as BO-
DONINA incertae sedis, included these two genera in his discussion of
zooflagellates at the 1981 session in Warsaw. According to him (V i ck
e r m a n, personal communication): Cercomonas and Heteromita are
clearly related to each other and sufficiently distinct from both chrysomonads
and sarcodines to merit a separate small order. Accordingly,
using the characteristics presented by him at the 1981 Congress, I propose
to create, with Vickerman as the sole authority, a new
order among MASTIGOPHORA.
Order CERCOMONADIDA Vickerman
Two heterodynamic acronematic flagella whose kinetosomes cap cone
of microtubules closely enveloping drawn out anterior part of nucleus;
cone apparently attached to nucleus; microtubules, some lying along
nucleus, not all subpellicular (as in Kinetoplastida)-, single, membranebounded,
postnuclear organelle of unknown function loosely capping
posterior part of nucleus; extrusomes resembling haptocysts of heliozoans
often associated with surface microtubule tracks; several mitochondria
with tubular cristae; food ingestion by pseudopodia; contractile vacuole
usually postnuclear, may be adbasal (as in Kinetoplastida).
Cercomonas, Heteromita
Some of the former members of RHIZOMASTIGIDA can be now
assigned to known flagellate and rhizopod taxa, and this is reflected in
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