Polyphasic taxonomy of Penicillium subgenus Penicillium A ... - CBS

J.C. FRISVAD &R.A.SAMSONIn contrast to P. vulpinum the conidiophores of theremaining species of the series retain their individualityand they are somewhat divergently arranged,giving the coremia their feathery appearance. Thecoremia of P. vulpinum are compact. Generally thecoremia of the Claviformia are larger and betterdeveloped on the natural substrate than on agarmedia.In P. clavigerum colonies are strongly synnematous.Synnemata are well-developed, acicular, with apointed top, often not showing a clear differentiationinto stalk and conidium-bearing area, usually simple,but sometimes branched near the top; conidiophoresborne over nearly the entire length of the stalk,though usually more concentrated on the terminalarea, one- to two-stage-branhced with elementscommonly appressed and smooth-walled. The stipesare variable in length, often long, sinuous, compressingthe body of the synnemata. The phialides have acylindrical basal part and a short, narrowed neck.Conidia are ellipsoidal and smooth-walled. P.clavigerum is mainly separated from the other speciesof the series Claviformia by the structure of thesynnemata. The coremia of most synnematous speciesof the subgenus Penicillium consist of a more orless, sterile stalk and a fertile capitulum, whereas thesynnemata of P. clavigerum show no clear differentiationinto stalk and capitulum. They are acicular andcomposed of a stalk, covered over nearly the entirelength with conidiophores.Pitt (1979) regarded P. clavigerum as a synonymof P. duclauxii, since the structure of their synnematais alike. Yet, P. clavigerum does not produce theacerose phialides of the series Duclauxii (subgenusBiverticillium) but is characterized by the flaskshapedphialides typical of the subgenus Penicilliumand consequently belongs in the latter subgenus.Moreover the penicilli and conidia, as well as thecultural appearance are quite different. P. clavigerumis placed here in the Claviformia (subgenus Penicillium)because of its morphological affinities with P.coprophilum and its biochemical affinities with P.glandicola. This classification based on morphologyis supported by chemotaxonomic evidence (Samsonet al., 1989, p. 140). P. duclauxii produce duclauxinand other secondary metabolites typical of the genusTalaromyces and subgenus Biverticillium (Frisvad etal., 1990d), and have no extrolites in common with P.clavigerum at all. In contrast to P. vulpinum, theconidiophores of P. clavigerum, like those of theremaining members of Claviformia, retain theirindividuality.In P. vulpinum, the cultures are strongly coremiform.Coremia consisting of a sterile stalk and asubglobose to ellipsoidal, fertile capitulum, comprisedof interwoven, anastomosing penicilli forminga hymenium-like layer. Conidiophore stipes of varyinglength, somewhat sinuous and interlaced, smoothwalled.Penicilli dichotomously two- to four-stagebranched,with both branches per branching pointnearly equal in length, all elements smooth-walled.Branches sinuous, gnarled, strongly interwoven, theultimate branches bearing 2-3 metulae. Phialidesslender, with a relatively long, cylindrical basal partand a short, slightly narrowed neck. Conidia ellipsoidal,smooth-walled, adhering in well-defined columns.The characteristic, well-developed coremia andthe dichotomously two- to four-stage-branhcedconidiophores distinguish P. vulpinum from all otherspecies of Penicillium. Raper & Thom (1949) proposedthe series P. claviforme to include the twospecies: P. claviforme (= P. vulpinum) and P.clavigerum. They included their P. claviforme seriesin the subsection Fasciculata since both speciesproduce well-defined coremia. This assigment wasaccepted by Samson et al. (1976) and Ramirez(1982). According to Pitt (1979) P. claviforme and P.clavigerum should be classified in the series Duclauxiiof the subgenus Biverticillium. However, thephialides of both species are characterized by a short,truncate neck. Acuminate necks, as occurring in thesubgenus Biverticillium were not observed by us.Using DNA sequence data, LoBuglio et al., 1994 alsoshowed that these two strongly synnematous speciesbelong in subgenus Penicillium.P. coprophilum, P. coprobium and P. concentricumresemble one another closely. Coremia, conidiophores,conidia as well as cultural characters(e.g. rate of growth and zonation of the cultures) areidentical. Their profiles of metabolites are, however,quite different. Moreover they show differences inthe colouration of their colony reverses. P. coprobiumcan produce white sclerotia, which are absent in theother two species. P. concentricum shows because ofits conidia and smooth-walled stipes more affinitieswith P. coprophilum than with P. glandicola. It isregarded here as a separate species near P. coprophilum.The Claviformia are separated from the Corymbiferaby their ellipsoidal conidia and their betterdevelopedcoremia. They differ from the Expansa bytheir more restricted growth and the more prominentcoremia. In addition the phialides of the Claviformiaare slender as compared with the robust conidia -bearing structures of P. expansum.This series is here amended to include all knownsynnematous coprophilic species of Penicillium.They all have predominantly smooth walled ellipsoidalconidia and all species produce patulin. Themembers of this group have several features in commonwith species in series Expansa and Urticicolaeincluding production of patulin and/or griseofulvinand roquefortine C, smooth walled stipes andsmooth-walled ellipsoidal conidia and the productionof synnemata.24