Richard E. Clopton

Standard Nomenclature and Metrics of Plane Shapes for Use in Gregarine Taxonomy

Abstract Current practice in gregarine (Apicomplexa: Eugregarinorida) taxonomy does not include a standard nomenclature and metric set for plane shapes even though most taxonomic works within the group depend on shape-based descriptions. The lack of a uniform shape nomenclature and metric set has produced considerable confusion in gregarine systematics: descriptions of species often are not directly comparable even among congeneric taxa. As a step toward unifying taxonomic practice within Eugregarinorida, a standard nomenclature and metric set for 278 plane shapes in 23 shape series is delineated.

Species density distributions as null models for ecologically significant interactions of parasite species in an assemblage

A multiple-kind lottery model is presented for use in determining whether species density distributions in parasite species assemblages reveal regularly occurring species-to-species interactions. The model utilizes a recurrence vector algorithm to rapidly calculate expected frequencies of species per host classes in such assemblages. These calculations have been a computational problem because the probability of a host individual acquiring one species of parasite is not necessarily equal to that of acquiring another species. Thus although the number of possible ways for a host to acquire x parasite species of a possible n is given by the familiar binomial expansion term n![x!(x!(n - x)!], each of these ways can have a different probability. The model is applicable to any system that mimics a multiple-kind lottery in which (1) successes are independent events and (2) it is possible to fail completely to acquire any parasites or their analogs. The algorithm is thus a null model for species density distributions in general. Application of the model is illustrated by host/parasite systems involving snails and trematodes, fish and their protozoan and platyhelminth parasites, and a relatively rich assemblage of parasites in bats.

The Roles of Ecological and Evolutionary Influences in Providing Structure to Parasite Species Assemblages

Parasite species assemblages currently are thought to range from isolationist to interactive, their dynamic properties being related to the number of species and types of hosts involved. The literature contains few experimental tests of this concept, however, and many of the host/parasite systems studied to date are not amenable to experimental manipulation. In this review, the presence of a parasite species, in a sample of host individuals, is considered to be an evolutionary phenomenon, but the parasites population structure is considered to be an ecological one. Studies that allow evaluation of these 2 influences are comparative in nature and include data from a series of homogeneous samples of host populations. A lottery model is presented, in which hosts acquire their assemblages of parasites by Monte Carlo type sampling from multiple kind arrays; the major structuring influence is the relative probability of becoming infected by various parasite species. Claims of parasite species interaction need to be supported by studies showing departures from the predictions of this model. The species density and infraassemblage diversity index distributions are recommended as quantitative tools useful in such work.

Phylogenetic relationships, evolution, and systematic revision of the septate gregarines (Apicomplexa: Eugregarinorida: Septatorina).

Abstract A phylogenetic hypothesis was constructed with the use of ssu rDNA sequence data from 27 eugregarine species parasitizing a variety of arthropod hosts and habitats. The data were used to address higher-level character transitions, identify clades, recognize supraspecific taxonomic groups, assess the existing gregarine classification, and assess the effects of host metabolic pattern and habitat transitions on the radiation of the septatorinid gregarines. Suprageneric character transitions for association form, association timing, syzygy, gametocyst dehiscence, and oocyst liberation are defined. New character search based on the proposed phylogeny produced a morphological character set that correlates strongly with the sequence data. These morphological character sets are mapped to the new septatorinid phylogeny. Existing superfamily groups within Septatorina were recovered and a new superfamily recognized. At the family level, the monophyly of Actinocephalidae and Stylocephalidae is confirmed and the polyphyly of Gregarinidae is partially resolved with the recognition of Blabericolidae. At the generic level, the monophyly of Protomagalhaensia and Xiphocephalus is confirmed, the polyphyly of Leidyana is partially resolved with the recognition of Blabericola, and the polyphyly of Gregarina is revealed but cannot be resolved without additional taxonomic data. High-level diversification of Septatorina resulted from adaptations of the gametocyst, allowing colonization of both terrestrial and sweet-water habitats. Major radiations within the group correlate with host metamorphic pattern, suggesting that evolutionarily, gregarine species track niche resources along lines of transmission; they do not necessarily track host species in evolutionary time. Gregarine assemblages within a single host species may be either vicariant assemblages, (i.e., products of coevolutionary, phylogenetic effects), or ecotypic assemblages, (i.e., products of ecological fitting and host switching). The following systematic or nomenclatural acts are committed. Stenophoroidea and Gregarinoidea are emended. Diagnoses of Stenophoroidea, Gregarinoidea, and Sphaerocystidae are revised. Stylocephaloidea n. supfam., Blabericolidae n. fam., and Blabericola n. gen. are recognized and erected. Blabericola princisi n. comb., Blabericola cubensis n. comb., Blabericola haasi n. comb., and Blabericola migrator n. comb. are recognized. Schneideria, Neoschneideria, and Paraschneideria are removed from Sphaerocystidae and placed in Actinocephalidae. Protomagalhaensia is removed from Hirmocystidae and placed in Blabericolidae. Pyxinia is removed from Stylocephaloidea: Actinocephalidae and placed in Stenophoroidea: Monoductidae.

Evolutionary Constraints on Population Structure: The Parasites of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska

Population and community descriptor values (parasites per host, prevalence per parasite species, variance/mean ratios, species density, and diversity indices) for the 7-species parasite community of 61 relatively homogeneous samples of Fundulus zebrinus (Pisces: Cyprinodontidae) in the South Platte River of Nebraska, U.S.A., taken over a 14-yr period, are reported. South Platte River streamflow fluctuates over 2 orders of magnitude on several time scales-monthly, annually, and over multiple year wet-dry cycles. Relatively homogeneous sampling of a single host species with several parasite species provided a system that allowed assessment of the contribution of evolved parasite life cycles to population structure in an everchanging environment. No significant negative species-to-species associations were observed. Species abundance, order of abundance, and diversity were affected most strongly by streamflow, with high water reducing prevalence and abundance of larval trematode parasites. Each parasite species had its characteristic long- and short-term patterns of variation in population descriptor values, with mostly long-term stability superimposed on sometimes extreme short-term fluctuations of descriptor values. The differences in these characteristic patterns were considered products primarily of the evolved life cycle traits and transmission mechanisms operating in the common fluctuating environment. The parasite community as a whole showed resilience, returning to preperturbation diversity following extended periods of high water.

HOST STADIUM SPECIFICITY IN THE GREGARINE ASSEMBLAGE PARASITIZING TENEBRIO MOLITOR

Reciprocal cross-stadia experimental infections were used to demonstrate stadium specificity within the gregarine assemblage parasitizing Tenebrio molitor, the yellow mealworm. Gregarina cuneata, Gregarina polymorpha, and Gregarina steini are characteristic parasites of larval T. molitor. Gregarina niphandrodes is a characteristic parasite of adult T. molitor. Experimental infections were produced in all homologous host-parasite combinations. No infection was produced in heterologous or cross-stadia combinations. This study introduces the concept of separate, distinct parasite niches corresponding to separate life cycle stages and established by known, predictable life cycle events within a single host species.

Calyxocephalus karyopera g. nov., sp. nov. (Eugregarinorida: Actinocephalidae: Actinocephalinae) from the Ebony Jewelwing Damselfly Calopteryx maculata (Zygoptera: Calopterygidae) in southeast Nebraska, U.S.A.: Implications for mechanical prey-vector stabilization of exogenous gregarine development

Abstract Calyxocephalus karyopera g. nov., sp. nov. (Apicomplexa: Eugregarinorida: Actinocephalidae: Actinocephalinae) is described from the Ebony Jewelwing Damselfly Calopteryx maculata (Odonata: Zygoptera: Calopteryigidae) collected along Turkey Creek in Johnson County, Nebraska, U.S.A. Calyxocephalus gen. n. is distinguished by the form of the epimerite complex: a terminal thick disk or linearly crateriform sucker with a distal apopetalus calyx of petaloid lobes and a short intercalating diamerite (less than half of the total holdfast length). The epimerite complex is conspicuous until association and syzygy. Association occurs immediately before syzygy and is cephalolateral and biassociative. Gametocysts are spherical with a conspicuous hyaline coat. Lacking conspicuous sporoducts they dehisce by simple rupture. Oocysts are axially symmetric, hexagonal dipyramidic in shape with slight polar truncations, bearing 6 equatorial spines, 1 at each equatorial vertex and 6 terminal spines obliquely inserted at each pole, 1 at each vertex created by polar truncation. The ecology of the C. karyopera–C. maculata host–parasite system provides a mechanism for mechanical prey–vector stabilization of exogenous gregarine development and isolation.

Developmental Niche Structure in the Gregarine Assemblage Parasitizing Tenebrio molitor

The exogenous developmental niche spaces of Gregarina cuneata and Gregarina polymorpha, parasites restricted to larval Tenebrio molitor, and Gregarina niphandrodes, a parasite restricted to adult T. molitor, were determined along temperature and humidity axes and associated with parasite niche space on the host resource axis. Gregarine gametocysts were incubated at controlled humidity (0, 10, and 20 mm Hg vapor pressure deficit) at 20, 25, 30, and 35 C to determine the environmental limits to survival and sporulation

New Methods for the Collection and Preservation of Spirorchiid Trematodes and Polystomatid Monogeneans from Turtles

Abstract New techniques and protocols for the field collection and preservation of spirorchiid trematodes and polystomatid monogeneans are delineated for inclusion in existing postmortem examination protocols for the parasites of turtles. Spirorchiid trematodes are collected in body and organ washes of citrated saline solution concentrated by sedimentation in a separatory funnel. Polystomatid monogeneans are collected by precise dissection and examination of the urinary and accessory bladders, nasal and oral cavities, and the conjunctival sacs and nictitating membranes of the eye. Fixation by distilled water osmotony or heat followed by preservation and storage in 95% undenatured ethanol are recommended to produce specimens for subsequent morphological and molecular analysis.

Nubenocephalus nebraskensis n. gen., n. sp. (Apicomplexa: Actinocephalidae) from Adults of Argia bipunctulata (Odonata: Zygoptera)

Nubenocephalus nebraskensis n. gen., n. sp. (Apicomplexa: Actinocephalidae) is described from trophozoites, sporonts, gamonts, and oocysts collected from adult Argia bipunctulata (Odonata: Zygoptera). The new genus is distinguished from existing acanthosporine genera by elongate dodecahedral oocysts, without equatorial faces, that are hexagonal in equatorial cross section with equatorial and terminal spines. The epimerite is very broadly ovoid and truncated posteriorly with equatorial lobiform tumidi that are posteriorly bilobate and do not form hooks, spines, or digitiform processes. The epimerite is borne on a long, slender stalk. The new species is also reported from naiads ofArgia bipunctulata and adults and naiads ofEnallagma civile (Odonata: Zygoptera).