S. T. Moss

Taxonomic studies of the Halosphaeriaceae: Remispora Linder, Marinospora Cavaliere and Carbosphaerella Schmidt

Further taxonomic studies of the genera of the Halosphaeriaceae are reported. Remispora, Marinospora and Carbosphaerella are characterised and include observations at the scanning and transmission microscope levels. The reasons for retaining the taxa Remispora and Marinospora are outlined.

Ultrastructure of Asci and Ascospore Sheath of Massarina thalassiae (Loculoascomycetes, Ascomycotina)

Ultrastructure of the marine lignicolous, bitunicate, ascomycete Massarina thalassiae is presented and compared with marine species of the genera Paraliomyces, Pleospora and Nimbospora. Asci of M thalassiae possess a thick endoascus, thin ectoascus and an ocular chamber. The bicelled ascospores are surrounded by an exosporial mucilaginous sheath similar to that of Paraliomyces lentifei-us.

New freshwater species of Ascotaiwania and Savoryella from Taiwan

Four new taxa are described, each having multiseptate ascospores with hyaline end cells; Savoryella limnetica, Ascotaiwania wulai, A. hsilio and A. sawada). Savoryella and Ascotaiwania are evaluated and separated by the following characters: Savoryella has broad, up to 8 μm paraphyses (sparse) that are septate and rounded at their ends, and smaller asci with an apical thickening containing a plugged pore and 3–septate ascospores; Ascotaiwania has narrow, filiform, septate paraphyses up to 2 μm wide, but these deliquesce early and are rarely observed in mature ascomata. Ascotaiwania also has asci with a well-developed apical ring and plugged pore and ascospores generally with more than 3 septa. Ultrastructural studies of A. lignicola showed that the ascopores are covered by a thin mucilaginous sheath and unitunicate asci with the wall comprising an outer, 30–40 nm electron-dense layer and an inner, 420–450 nm, thick, electron-transparent layer. Asci have a well-developed apical apparatus consisting of an electron-dense apical ring with a plug. The plug deliquesces prior to ascospore release. The ascospore wall comprises an electron-dense episporium and a less electron-dense mesosporium. External to the episporium is a fibro-granular sheath.

Spore appendage development in the lignicolous marine pyrenomycetes Chaetosphaeria chaetosa and Halosphaeria trullifera

Spore appendage development in Chaetosphaeria chaetosa and Halosphaeria trullifera is described. In H. trullifera the polar appendages are initially closely adpressed to the ascospore wall but later separate and finally form long mucilaginous strands at maturity. These appendages are compared with those described for Halosarpheia. H. trullifera is transferred to Halosarpheia and the reasons discussed. In Ch. chaetosa the appendages are formed by fragmentation of an exosporium to form irregular sheet-like, equatorial appendages and polar appendages; the latter are described for the first time in this species. Appendage development is compared with that described for Corollospora .

Halosarpheia aquadulcis sp. nov., a new lignicolous, freshwater ascomycete from Taiwan

A new freshwater ascomycete, Halosarpheia aquadulcis sp. nov. (Halosphaeriaceae; Halosphaeriales), is described and illustrated and compared with other species of Halosarpheia and Aniptodera from marine and freshwater habitats.

Ultrastructure of asci and ascospores of two mangrove fungi: Swampomyces armeniacus and Marinosphaera mangrovei

A collection of Swampomyces armeniacus made in North Queensland, Australia, and with measurements slightly smaller than those of the type material but within the range for the species, was studied. Ultrastructural examination elucidated the nature of structures observed previously at the light microscope level and revealed features not recorded in the original description. The ascus apex is truncated with an apical amorphous thickening, and the ascospore wall comprises three layers: mesosporium; episporium; exosporium. In mature ascospores the episporium is ornamented, the exosporium is lost and a mucilaginous sheath enrobes the spore. Examination of Marinosphaera mangrovei showed that the ascospores possess a verrucose surface which is subsequently covered by a fibrillar matrix which may be involved in spore attachment.

Ultrastructural studies on the aquatic ascomycetes Annulatascus velatisporus and A. triseptatus sp. nov.

Annulatascus species are common freshwater ascomycetes in the tropics. In this paper, the type species, Annulatascus velatisporus, and a new species, A. triseptatus, are described and illustrated at light and electron microscope levels. Annulatascus triseptatus differs from A. velatisporus in having three-septate ascospores surrounded by a thin sheath. The asci of both species have bilamellate ascus walls and a bipartite apical ring. The upper part of the apical ring differentiates from the inner ascus wall layer and the lower part elongates downwards during maturation. The mesosporium is the first formed ascospore wall layer followed by the episporium, which is covered with verruculose ornamentations. The mucilaginous sheath of the ascospores is fibrillar or amorphous depending on the fixation methods employed, and appears to be derived from the episporial verruculose ornamentations.

Ultrastructural observations of asci, ascospores and appendages of Massarina armatispora (Ascomycota)

Massarina armatispora (Ascomycota, Dothideales, Lophiostomataceae) is described for the first time at the ultrastructural level. Two new structures were observed for this species. Firstly, the ascospores were shown to possess polar chambers formed from the episporium and which contained a fibrillar material and secondly, a lateral fibrillar appendage-like structure. The similarities between marine ascomycetesMassarina armatispora, Massarina thalassiae andParaliomyces lentiferus are discussed.

Temporal changes in the level of infestation of Simulium ornatum Meigen (Complex) (Simuliidae: Diptera) larvae by the endosymbiotic fungus Harpella melusinae Lichtwardt (Harpellales: Trichomycetes)

The fungus Harpella melusinae (Harpellales: Trichomycetes) is obligately associated with the midguts of larval Simuliidae (Diptera). The level of infestation of a population of Simulium ornatum by H. melusinae was monitored at a stream in Hampshire, England. Significant temporal changes in the level of infestation were recorded during monthly and weekly collections; a twenty-fold increase being recorded over a nine-day period. Possible mechanisms by which these changes occur are discussed.

Ultrastructure of Antennospora salina comb. nov.

The ultrastructure of the ascospore and appendages of Halosphaeria salina was studied. Ascospore walls comprise a two-zoned mesosporium, the outer more electron-dense, and an electron-dense episporium enclosed by a layer of mucilaginous material. Ascospores have 3–5 subpolar appendages at each pole that appear as electron-dense striations and an amorphous core. Striations arise as outgrowths of the outer zone of the mesosporium, which is thickened at the point of attachment of the appendage to the spore wall. Halosphaeria salina is compared to H. appendiculata and Antennospora quadricornuta . It has more features in common with A. quadricornuta , particularly the ontogeny of the spore appendage, and is therefore assigned to the genus Antennospora .