Should there be a separate code of nomenclature for the protists?

The present Botanical and Zoological Codes of Nomenclature are often inadequate for resolution of all the peculiar problems caused by the very nature of the numerous and diverse groups of the so-called 'lower' eukaryotic organisms known as protists. Whether or not a separate code should therefore be created for these species--many but not all of which are unicellular in structure and microscopic in size--is complicated by several factors. The principal one is related to the wide dispersal of protists throughout many taxonomic classes and phyla/divisions; sometimes even multiple kingdoms are involved. If recognition of a single kingdom Protista is no longer tenable, then even the concept of one code per kingdom is not applicable. Other difficulties arise primarily from long-standing differences in major provisions of present Botanical and Zoological Codes. Numerous 'ambiregnal' forms exist, species currently under dual code jurisdiction. The matter of names for suprafamilial taxa of protists, irrespective of their ultimate kingdom assignment, poses another set of concerns not yet resolved. A plea is made to recognize the legitimacy of having distinct high-level ranks for protist species that seem to be widely separated phylogenetically from fellow protists or from other eukaryotic assemblages.

Description of two species of nassophorean ("Hypostome") ciliates, Nassulopsis elegans (Ehrenberg, 1833) and Zosterodasys derouxi n.sp., with comments on their systematic and phylogenetic affinities.

Most of the so-called "lower hypostomes", nassophorean ciliates in the most recent classifications of the phylum Ciliophora, have been little studied in modern times (e.g., employing methods of silver impregnation, a technique widely considered indispensable in comparative taxonomic work on these protists today). In this paper, we present descriptions of two species, a new strain of Nassulopsis elegans (Ehr., 1833) and Zosterodasys derouxi n.sp., based primarily on use of the pyridinated silver carbonate method of Fernández-Galiano. From our own data, especially on the oral hypostomial frange of the first organism and the true somatic synhymenium of the second, and review of the relevant literature, we suggest that the phylogenetic affinities of these forms need to be reassessed. We also tentatively propose some changes in the suprafamilial classification of the ciliate groups involved. While recognizing the need for additional information that can be supplied only by future ultrastructural studies and comparative morphogenetic investigations, we briefly offer the following two speculative ideas at this time: (1) that Nassulopsis be removed from the order Synhymeniida and be considered an evolutionarily primitive genus of the "higher" order Nassulida; and (2) that Zosterodasys be considered a "pivotal" primitive nassophorean that may have given rise, phylogenetically, not only to the more evolved groups of its own class (the Nassophorea) but also to the (primitive groups of the) entire neighboring class Phyllopharyngea.

The quest for the ancestor of the Ciliophora: a brief review of the continuing problem.

Although the assumption has long been made that the Ciliophora arose from flagellates, limited progress has been made in determining exactly what extant group - flagellate or other - may best resemble the ancestral "preciliate" assemblage. The distinctiveness of the ciliates and of the many protist phyla containing flagellated stages in their life cycles makes the recognition of potentially homologous features difficult. The suggestion that there may be a phylogenetic relationship between dinoflagellates and ciliates, while seeming unlikely from consideration of a number of specialized characters, is attracting increased attention. This is because some basic similarities (possibly shared derived characters) are characteristic of many species from both groups: cortical alveoli, tubular mitochondrial cristae, kinetidal systems, acentric mitoses with persisting nuclear envelope, functional cytostome, extrusomes (mucocytsts and explosive trichocysts), locomotory organelles, and small subunit rRNAs (close structural similarity values). But many questions remain unanalyzed or unanswered, and caution is still advisable in drawing any firm conclusions about the evolutionary closeness of ciliates and dinoflagellates.

The kingdom Protista and its 45 phyla.

Because most recent treatments of the protists ('lower' eukaryotes comprising the kingdom PROTISTA Haeckel, 1866) have been preoccupied with either a 'phylogenetic-tree' approach or a discussion of the impact of possible endosymbiotic origins of major intracellular organelles, the overall systematics of the group, from taxonomic and nomenclatural points of view, has been almost totally neglected. As a result, confusion over contained phyla, their places in a classification scheme, and even their names (and authorships) is growing; the situation could become chaotic. The principal objective of the present paper is to recognize the taxonomic interrelationships among all protist groups; and it includes the specific proposal that some 45 phyla, defined and characterized, be assigned to 18 supraphyletic assemblages within the kingdom PROTISTA (itself redefined and contrasted with the other eukaryotic kingdoms recognized here: ANIMALIA, PLANTAE and FUNGI). Vernacular terms are employed for identification of the 18 assemblages, but defensible formal names are proposed at the level of phylum. None is presented as new: authorship-and-date credits are given to preceding workers on the taxonomy of the many groups involved. By presenting taxonomic characterizations as well as relevant nomenclatural data for each taxon described, a comprehensive scheme of overall higher-level classification within the kingdom emerges that may be considered to serve as a solid base or 'taking-off point' for future discussions. The 18 supraphyletic groups and their phyla (in parentheses and including authorships and dates of their formal names) are as follows: I. The rhizopods (phyla Karyoblastea Margulis, 1974; Amoebozoa Lühe, 1913; Acrasia Van Tieghem, 1880; Eumycetozoa Zopf, 1885; Plasmodiophorea Zopf, 1885; Granuloreticulosa De Saedeleer, 1934; incertae sedis Xenophyophora Schulze, 1904). II. The mastigomycetes (Hypochytridiomycota Sparrow, 1959; Oomycota Winter, 1897; incert. sed. Chytridiomycota Sparrow, 1959). III. The chlorobionts (Chlorophyta Pascher, 1914; Prasinophyta Christensen, 1962; Conjugatophyta Engler, 1892; Charophyta Rabenhorst, 1863; incert. sed. Glaucophyta Bohlin, 1901). IV. The euglenozoa (Euglenophyta Pascher, 1931; Kinetoplastidea Honigberg, 1963; incert. sed. Pseudociliata Corliss & Lipscomb, 1982). V. The rhodophytes (Rhodophyta Rabenhorst, 1863). VI. The cryptomonads (Cryptophyta Pascher, 1914). VII. The choanoflagellates (Choanoflagellata Kent, 1880).(ABSTRACT TRUNCATED AT 400 WORDS)

Stephanopogon, a phylogenetically important "ciliate," shown by ultrastructural studies to be a flagellate.

A benthic marine protist (Stephanopogon) with a homokaryotic nucleus has long been considered to be a gymnostome ciliate. It has been important in hypotheses concerning the origin of ciliates, the evolution and origin of the dual nuclear apparatus of contemporary species of the Ciliophora, and the origin of the multicellular Eumetazoa. Ultrastructural observations reveal that the organism should be reclassified as a flagellate, despite its superficial resemblance to ciliates.

What are the taxonomic and evolutionary relationships of the Protozoa to the Protista?

In order to consider the problems of protist-protozoan interrelationships in proper perspective, a new "packaging" of phyla within the great kingdom Protista is proposed. Although it is based largely on historical groupings and is admittedly "unnatural" (nor are taxonomic names proposed for my five supraphyletic groupings), the arrangement may clarify some long-persisting problems, especially with regard to mixed algal-protozoan groups and/or phylogenies. Some three dozen phyla are recognized as comprising the kingdom, with the number that might be considered as "protozoan" ranging from 10 to 25, depending on one's viewpoint. No taxon should have the formal name "Protozoa", "Phytoflagellate" and "zooflagellate" are also misleading categories. Taxonomic and evolutionary relationships of phyla containing protozoa (with small "p") are inextricably intermeshed with those of other protist phyla, and thus no unified protozoan super-group exists.

Method for coding data on protozoan strains for computers.

Traditionally, observations on the nature of protozoa have been published in periodicals or books, or remain buried in research notebooks. The retrieval and processing of information on a particular species or strain are dependent solely upon individual investigators. Although various modern methods have been applied to the study of protozoa, no attempt has been made to develop a system with which information on protozoan strains can be stored, retrieved easily, and processed for various analyses by computer technology. Based upon an existing system for encoding data on bacterial strains, a complementary system applicable to protozoan strains was developed and is described herein.

A newly revised classification of the protozoa.

The subkingdom Protozoa now inclues over 65,000 named species, of which over half are fossil and approximately 10,000 are parasitic. Among living species, this includes approximately 250 parasitic and 11,300 free-living sarcodines (of which approximately 4,600 are foraminiferids); approximately 1,8000 parasitic and 5,100 free-living flagellates; approximately 5,600 parasitic "Sporozoa" (including Apicomplexa, Microspora, Myxospora, and Ascetospora); and approximately 2,5000 parasitic and 4,700 free-living ciliates. There are undoubtedly thousands more still unnamed. Seven phyla of PROTOZOA are accepted in this classification--SARCOMASTIGOPHORA, LABYRINTHOMORPHA, APICOMPLEXA, MICROSPORA, ASCETOSPORA, MYXOSPORA, and CILIOPHORA. Diagnoses are given for these and for all higher taxa through suborders, and reporesentative genera of each are named. The present scheme is a considerable revision of the Society's 1964 classification, which was prepared at a time when perhaps 48,000 species had been named. It has been necessitated by the acquisition of a great deal of nex taxonomic information, much of it through electron microscopy. It is hoped that the present classification incorporatesmost of the major changes that will be made for some time, and that it will be used for many years by both protozoologist and non-protozoologists.