Evaluation of the Diagnostic Features of Some Species of Penicillium Section Divaricatum

Summary

The study was carried out with about 200 isolates mainly from Czechoslovakia and belonging to Penicillium sect. Divaricatum: P. janczewskii, P. canescens, P. melinii, P. radulatum, P. janthinellum and P. simplicissimum. The type isolates were compared according to their micro- and macromorphology. The following are recommended as diagnostical features: the branching of conidiophores, divergence of metulae and phialides and their length and the character of conidia. The length of phialides is accurately measured omitting the neck, as neck length can be variable in a single isolate. P. janczewskii and P. daleae can be distinguished satisfactory on the basis of their micromorphology and colonies. In both species colonies are very variable in degree of sporulation, in conidial colour and in exudate and reverse colours. P. granatense is a synonym of P. janczewskii based on our observation of the type isolate. Isolates of P. canescens have good micromorphological distinguishing features. Isolates of P. melinii are very similar in micromorphology and colony character to P. radulatum, which has been only found once in Czechoslovakia. The type isolate of P. melinii studied during our investigation is different from the original description and also from our own isolates. A great number of soil isolates could be identified as either P. janthinellum or P. simplicissimum because their micromorphology is very similar. They probably represent one species.