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Electron microscopy of the septa in hyphae of Dipodascus species showed a narrow, central pore in D. uninucleatus and plasmodesmata in D. aggregatus, Ascospores in D. uninucleatus are small, oval, or reniform; in D. aggregatus they are much bigger with a wall which is first narrow and later expands considerably. The description of the spores of the type species, D. albidus, of which no strains were available for examination, agrees with that of D. aggregatus. Apart from the features mentioned above, D. uninucleatus differs from D. albidus and D. aggregatus in other important characteristics, such as the method of gametangia formation and the structure of the cell wall.

Cephaloascus fragrans Hanawa and Dipodascus aggregatus Francke-Grosmann occasionally serve as a source of food or supplement other food sources for ambrosia beetles (Coleoptera: Scolytidae). Dipoda...

The growth of a strain of Dipodascus aggrrgatus Francke-Grosmann was strongly promoted by the aliphatic aldehyde nonanal. The highest effect was found with 80–160 μmol of nonanal per 1. The growth-promoting activity of nonanal is principally the result of an ability to shorten the lag phase. Neither the maximum value for growth nor the growth rate seem to be increased. The growth-promoting activity of nonanal could be observed only if the cells used for inoculation were taken from a culture in the phase of accelerated growth. The highest growth-promoting activity was observed when the nonanal was added before inoculation, a large effect was still observed when it was added 24 hours after inoculation, but there was no effect when it was added 33 hours after inoculation. The growth-promoting activity of nonanal remained unchanged when a mixture of 15 vitamins and growth factors was given to the medium. Nonanol and nonanoic acid stimulated growth, although to a lower degree than nonanal. There was a gradual increase in the growth-promoting effect of nonanal as the pH of the medium was increased between 3.0 and 8.0, showing that this effect is most pronounced at the higher pH values.

The production of volatile compounds by Dipodascus aggregatus was studied in relation to the oxygen concentration in the medium. Oxygen concentration was determined with a Clark oxygen electrode and volatile compounds in the atmosphere above the culture by a gas chromatographic technique. Shake cultures of the fungus in its stationary phase of growth were very sensitive to a decrease in oxygen concentration in the presence of residual glucose. Anaerobic conditions induced production of volatile compounds that continued for many hours. The pattern of production of volatile compounds observed under conditions of low oxygen concentration during the stationary phase of growth differed from that obtained under aerobic conditions during the exponential phase of growth.

A new genus and species are established for a Hemiascomycete growing on Corticium microsporum, a member of the Thelephoraceae. The fungus is known from three collections made in different localities in Ontario. It is characterized by a limited mycelial growth in the subhymenium of the Basidiomycete where it also produces more or less elongate and coiled ascogonial branches and hypha-like antheridial branches, each female branch producing a single ascus which grows through the hymenium of the supporting fungus and protrudes prominently beyond the basidia. Phylogeny in the lower Ascomycetes is considered briefly and evidence is presented indicating relationship of the fungus in question with Dipodascus and Endomyces.

Any student of fungi is inevitably impressed by instances of apparent parallel evolution. Indeed, it is these homoplastic tendencies that make it so difficult to achieve 'natural' classifications within the Fungi. There are many well-known examples. The holocarpic olpidioid thallus seems to have arisen independently in a number of separate orders of Phycomyces. This distinctive type is found in Olpidium (Chytridiales), Olpidiopsis (Lagenidiales) and Anisolpidium (Hyphochytriales). Again the macroscopic hypogeal fruit-body, adapted apparently to rodent dispersal, has evolved in Endogone (Mucorales), in the Hymenogastraceae (Basidiomycetes) and along several seemingly distinct lines in Ascomycetes (e.g. Elaphomyces and Tuber). The intracellular haustorium, formed as a branch from the main, and usually intercellular, mycelium, is found for example in Zoopagales, Peronosporales, Erysiphales and Uredinales, having probably evolved independently in all these orders. The perithecium of, for instance, Sordaria and the pseudothecium of such a fungus as Sporormia are biologically similar but developmentally very different, so that again parallel evolution seems to have occurred. In Hymenomycetes the transition from gills to the polyporous condition appears to have happened again and again, for example, along the Mycena-Mycenoporella line and along the Paxillus-Boletus pathway. I have been at pains in recent years to attempt to demonstrate the independent development of the tetra-radiate conidium in many different ways amongst aquatic Hyphomycetes. Recently I have been struck by the stalked spore-drop as another example of homoplasy and this is the subject of the present note. Six very different fungi with this type of apparatus are illustrated in Fig. i namely: Mucor ramannianus Moeller in Phycomycetes; Dipodascus uninucleatus Biggs, Cephaloascus fragrans Hanawa (=Ascocybe grovesii Wells) and Ceratocystis adiposa (Butl.) C. Moreau in Ascomycetes; and Gliocladium roseum (Link ex Fr.) Bainier and Graphium cuneiferum (Berk. & Br.) Mason & M. B. Ellis in the Fungi Imperfecti. Further the same essential mechanism is figured in Dictyostelium discoideum K. B. Raper, although most would not include this organism in the Fungi in spite of the fact that it has been studied largely by mycologists. First the spore-drop itself may be considered. In Mucor it arises from the conversion of a sporangium into a sporangial drop following the solution of the 'diffluent' sporangial wall. In Dipodascus it is the extruded contents of a large, many-spored ascus. In Cephaloascus it is formed from a compact group of small 4-spored asci the walls of which are deliquescent. In Ceratocystis it is a slimy mass of minute ascospores which exude at the ostiole of a perithecium. In Gliocladium and Grap hium it is a mass of conidia (phialospores) produced, together with slime, from a terminal group of phialides. In Dictyostelium it is a mass of encysted amoebae in a fluid matrix.

Strains in the culture collection of the Centraalbureau voor Schimmelcultures under the generic namesEndomyces andEndomycopsis were compared with related genera of filamentous and yeast-like fungi. The genusEndomyces is accepted for ascigerous states ofGeotrichum; 6 species are keyed out and discussed. The genus nameEndomycopsis is rejected as it is an obligate synonym ofSaccharomycopsis. ForEndomyces javanensis, Endomycopsis platypodis andSaccharomycopsis synnaedendra the new generaArthroascus, Hormoascus andBotryoascus are proposed; the genusGuilliermondella is reintroduced. Briefly discussed are the generaSchizosaccharomyces, Eremascus, Dipodascus, Ascoidea, Cephaloascus, Ambrosiozyma andCrebrothecium. A key is given for the genera of yeast-like “ascomycetes” with septate hyphae. Some species described asGeotrichum are transferred to other genera.

Dipodascus uninucleatus Biggs was isolated from a dead pupa of Drosophila melanogaster. Biggs (1937) reported that this fungus grew on Ai variety of media including liquid sugars, potato glucose agar, 1 per cent lactose agar, and malt extract agar. The latter medium permitted the best growth. Dulaney and Grutter (1950) noted that D. uninucleatus failed to grow in a vitamin-free medium, although normal growth resulted in the presence of yeast extract. Their investigation of the vitamin requirements of this yeastlike fungus showed that a mixture of biotin and thiamine gave growth equivalent to that obtained with use of a mixture of 12 vitamins. Addition of nucleic acids did not increase the amount of growth. These investigators also reported that D. uninucleatus utilized ammonium nitrogen, but not urea or nitrate nitrogen. During a study of pigmentation in cultures of D. uninucleatus and Aspergillus niger (Kuehn, 1952; Shanor and Kahn, 1949) it became necessary to investigate the growth responses and requirements of D. uninucleatus. The purpose of this report is to present the results pertaining to the nutritional requirements of this organism.

SummaryDipodascus belongs to the family Dipodascaceae (Endomycetales, Hemiascomycetidae). The genus is characterized by lacking ascogenous hyphae and ascocarps, and possessing typically ∞-spored an...