Robert W. Lichtwardt

ZYGOPOLARIS, A NEW GENUS OF TRICHOMYCETES PRODUCING ZYGOSPORES WITH POLAR ATTACHMENT

SUMMARY A new monotypic genus of the fungal order Harpellales (Genistellaceae) has been found in three localities in the United States inhabitating the guts of mayfly nymphs, Ephemerella and Baetis. Mature sporulating thalli of Zygopolaris ephemeridarum may be found protruding from the the anus of the host into the aquatic environment. Released trichospores do not appear to have basal appendages, as do most other Harpellales, but evidence of rudimentary appendage formation has been found in the generative cells. Zygospores are attached at one pole, and resemble those of Carouxella (Harpellaceae). The similarities of the two genera and two families are discussed, as well as the four types of zygospores recognized in the Harpellales. Zygopolaris, a new genus of Trichomycetes growing in the hindgut of mayfly nymphs in flowing streams, has been found in several different areas in western United States, thus indicating that it may be widespread. The genus is monotypic, like the majority of Harpellales genera (Manier and Lichtwardt, 1968; Lichtwardt, 1972). Its distinctive characteristics are attachment of zygospores at one pole, the lack of welldefined trichospore appendages, and projection of thalli from the host anus. All attempts to culture the species, Zygopolaris ephemeridarum, were unsuccessful, and all observations were made from material dissected from the living hosts. The majority of measurements and photographs were taken from distilled water mounts prior to their infiltration with lactophenol containing cotton blue.

Trichomycetes in Argentinean aquatic insect larvae

Investigations of larval aquatic Diptera (Chironomidae, Simuliidae, Culicidae), Coleoptera (Scirtidae), and Plecoptera (Gripopterygidae, Notonemouridae) in Buenos Aires Province and three Provinces...

Studies on the Nutritional Relationship of Larval Aedes Aegypti (Diptera: Culicidae) with Smittium Culisetae (Trichomycetes)

SUMMARY Axenic larvae of the mosquito, Aedes aegypti, were reared singly on a sterile semidefined medium from which required vitamins and sterols were individually deleted. Trichospores obtained from axenic cultures of the fungus, Smittium culisetae (Trichomycetes), were added to the medium to infest the hindguts of the larvae. First instar larvae invariably became heavily infested from the original spore inoculum, but infestations were often not maintained in the subsequent larval instars. In some instances thalli attached to the external cuticle of living larvae. With the introduction of S. culisetae, larvae were able to attain at least one additional instar when reared without riboflavin, pyridoxine or nicotinamide. No such improvement in larval growth was noted with S. culisetae upon the omission of thiamine or Ca pantothenate. In the absence of sterols larvae did not develop beyond the fourth instar, but following the addition of S. culisetae, one out of 45 larvae pupated. Both the lipid extract and dead whole mycelium of S. culisetae are adequate sources of sterols for larvae, and larvae are able to utilize desmosterol, the predominant sterol in Smittium spp. Sparse free mycelial growth was evident in the medium in those vitamin and sterol tests where larvae demonstrated an improvement in growth; hence the free mycelium may have been serving as a dietary source of nutrients. It is possible that mosquito larvae growing under some conditions of nutritional stress may be provided with required nutrients through infestations of S. culisetae in their guts.

Molecular variation within and among species of Harpellales

Intra- and interspecific variation of the nu- clear ribosomal internal transcribed spacers (ITS) of 77 Smittium isolates and related genera was studied using RFLP. Due to the sequence and length varia- tion encountered, the ITS is unsuitable for compar- ison at the species level within Smittium, as presently delimited. Intra- and interspecific variation of 18S rDNA was also analyzed. Cladistic analysis of 32 new 18S rDNA sequences resolved at least five lineages and suggests that Smittium is not monophyletic. In addition, 17 18S rDNA sequences from 5 orders of Zygomycota were included to assess phylogenetic re- lationships with the Trichomycetes. The kickxellid or- igin of Trichomycetes was not strongly supported.

Trichomycetes in aquatic insects from southern Chile.

AbstractEleven species of gut fungi and one protist are reported from the Valdivia region of southern Chile from lotic larvae of Diptera [Ceratopogonidae (biting midges), Chironomidae (nonbiting midges), Simuliidae (blackflies), Tipulidae (craneflies)] and Ephemeroptera [Baetidae (mayflies)]. Five are new species of Harpellales (Zygomycota: Trichomycetes): Harpella meridianalis, Smittium cylindrosporum, Sm. imitatum, Sm. simulatum, and Stachylina ceratopogonidarum. One is a new species of Amoebidiales, Paramoebidium grande. The three new species of Smittium were cultured axenically, and isozyme analyses indicated they are clearly distinct from other cultured species of Smittium, even though Sm. imitatum and Sm. simulatum are indistinguishable on the basis of trichospore morphology from two widely distributed species, Sm. simulii and Sm. culicis, respectively. Four of six previously known species collected in Chile had been found prior to this study only in the Northern Hemisphere.

Trichomycete insect symbionts in Great Smoky Mountains National Park and vicinity.

Collections of trichomycete symbionts of larval aquatic insects in Great Smoky Mountains National Park and vicinity in the southern Appalachian region of the USA resulted in finding many taxa of Harpellales, including an unusual new monotypic genus, Barbatospora ambicaudata in Simuliidae, and five new species in Thaumaleidae or Chironomidae, Harpellomyces montanus, Smittium lentaquaticum, Sm. minutisporum, Stachylina gravicaudata and St. stenospora. In addition a new species of Amoebidium (Amoebidiales), A. appalachense, attached to the anal tubules of bloodworms (Chironomidae) is described. Axenic cultures of three of the new taxa were obtained, plus Sm. culisetae. Fourteen identified species representing 13 genera of previously known Harpellales are recorded from Plecoptera, Ephemeroptera and Diptera, as well as a new Dipteran host record for an unidentified harpellid that was found in a Blephariceridae. Also identified were Paramoebidium corpulentum and many undetermined species of Paramoebidium (Amoebidiales) from four orders of aquatic insect larvae. The occurrence of an Enterobryus species in Diplopoda and another Eccrinales from an aquatic beetle is noted.

Some cultural and ultrastructural aspects of Smittium culisetae (Trichomycetes) from mosquito larvae.

SUMMARYSmittium culisetae, isolated from the hindgut of a mosquito larva, grew in a liquid tryptone-glucose medium over a range of temperatures from 5 to 32 C. The maximum rates of growth were in t...

Trichomycetes (Zygomycota) in the digestive tract of arthropods in Amazonas, Brazil

Eight species of Harpellales and three species of Eccrinales (Zygomycota: Trichomycetes) were found associated with the digestive tract of arthropods from terrestrial and aquatic environments in the central Amazon region of Brazil. New species of Harpellales include: Harpella amazonica, Smittium brasiliense, Genistellospora tropicalis in Simuliidae larvae and Stachylina paucispora in Chironomidae larvae. Axenic cultures of S. brasiliense were obtained. Probable new species of Enterobryus (Eccrinales), Harpella, and Stachylina (Harpellales) are described but not named. Also reported are the previously known species of Eccrinales, Passalomyces compressus and Leidyomyces attenuatus in adult Coleoptera (Passalidae), and Smittium culisetae and Smittium aciculare (Harpellales) in Culicidae and Simuliidae larvae, respectively. Comments on the distribution of some of these fungi and their hosts in the Neotropics are provided.

Immunological studies on the fungal genus Smittium (Trichomycetes).

Immunological comparisons of cultured species of Smittium isolated from the hindguts of Diptera larvae were made using immunoelectropho-retic and immunodiffusion methods. Antisera were produced in ...

Fine structure of the trichomycete, Harpella melusinae, from black-fly guts

SummaryThe fungus, Harpella melusinae, attached to the peritrophic membrane of black-fly larvae, was fixed in glutaraldehyde-acrolein-osmium and in KMnO4. The holdfast does not penetrate the peritrophic membrane, and is comprised of many finger-like outgrowths (“digits”) surrounded by secretions of cementing substance that arise from a specialized basal part of the thallus. Undifferentiated cells contain many organelles, membranes, and lipid droplets commonly found in other phycomycetes, but in addition contain large concentrations of electron-opaque material with vesicles and tubules. The cytoplasm also has crystals in membrane-bound vesicles, myelin-like aggregations of membranes, and large nuclei with associated semi-circular plaques. Septa with small pores like bordered pits, plugged with an electron-opaque material, resemble those of other Harpellales and Linderina (Mucorales). As a spore grows outward, 4 appendages are formed within the generative cell, attached to the base of the spore body, and form a spiral between the wall and plasmalemma. “Forming vescles” transport material from the cytoplasm to the growing appendages, resulting in a periodic structure of alternating dark and light bands. Mature spores have a thick, wavy (in cross section) inner wall and a loose outer wall, and are separated from the generative cell by a septum with a pore.