Neotypification of the Genus Trichosporon

Antonie van Leeuwenhoek 61: 285-288, 1992. 1992 KluwerAcademic Publishers. Printed in the Netherlands.

Neotypification of the genus Trichosporon

E. Gu6ho ~, G.S. de Hoog23 & M.Th. Smith 4 Unit~ de Mycologie, lnstitut Pasteur, 28, rue du Docteur Roux, 75724 Paris 15, France; 2 Centraalbureau voor Schimmelcultures, P.O. Box 273, 3740 A G Baarn, The Netherlands; 3 Department of Molecular Cell Biology, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands; 4 CBS Yeast Division, Julianalaan 67, 2628 BC Delft, The Netherlands

Accepted in revised form 5 February 1992

Key words: Trichosporon, basidiomycetous yeasts, nomenclature, taxonomy, white piedra, medical mycology

Abstract

The currently accepted type species of the genus Trichosporon Behrend is T. beigelii. This species has formerly been regarded as identical to T. cutaneum. However, these fungi are now known to represent separate species with different ecology. The first species described in Trichosporon was T. ovoides, an agent of human white piedra. A neotype strain is designated for this species, while a lectotype strain is indicated for T. cutaneum. The name T. beigelii is considered as doubtful and consequently cannot be maintained.

Since the first monographic treatments of yeasts by introduced a new name, Trichosporon ovoides researchers of the 'Dutch School' (Diddens & Lod- Behrend (1890), because Pleurococcus is a genus of der 1942), the genus Trichosporon Behrend has Algae, while Behrend clearly recognized his orga- been typified by T. beigelii (K/ichenm. & Rabenh.) nism to be a fungus. No material is known to be Vuill. or by T. cutaneum (de Beurm. et al.) Ota, preserved, but Behrend's clear descriptions allow a depending on distinction or synonymy of the spe- comparison with presently available live strains. cies or on the assumed dubious character of T. Behrend's (1890) specimen consisted of hairs beigelii. Recent genome data (Gu6ho et al. 1992) from a mustache of a European patient. The fungus have shown that T. cutaneum is a well-recognizable formed characteristic, light coloured, spindle- species with a Q-10 coenzyme system, different shaped nodules at irregular distances on the hair from strains identified as T. beigelii, having Co-Q 9, shaft over a length of 4-5 mm; the hairs themselves This requires a re-evaluation of the generic typ- remained unaffected and did not break. After iso- ification. The first description of a possible Tri- lation the fungus formed punctiform, initially moist chosporon species was that of Pleurococcus beigelii and glistening colonies which later merged and de- Kfichenm. & Rabenh. (Rabenhorst 1867). It was veloped a snow-white, farinose covering. Marginal found on hairs of a wig. The description, however, hyphae were seen to grow into the substrate, giving was very short and hardly interpretable; no materi- the colony a star-shaped appearance. Microscop- al is known to be preserved. ically, poorly branched hyphae were seen which The generic name Trichosporon was introduced readily disarticulated into short-cylindrical to ovoi- by Behrend (1890) for a similar organism causing dal cells. human white piedra ('Trichomycosis nodosa'). He Behrend (1890) compared his material with a 286 specimen from South America sent to him by Ju- ably concerned a case of black piedra now known hel-R6noy (1888). This strain was also grown in to be caused by Piedraia hortae (Brumpt) Fonseca culture on various media. It was considered to rep- & de Ar6a Le~o. In later literature, the two generic resent the same species. A further South American names have frequently been mixed up, e.g. by specimen, sent to Behrend by Osorio was judged to Dodge (1935) and more recently by Farr et al. be identical on the basis of characteristics seen on (1979). the hair; this strain could not be grown. In 1908, Castellani correctly took up the generic A chronology of later described, similar species name Trichosporon Behrend and introduced two from human white piedra and subsequent nomen- more names for piedra fungi, viz. T. foxi Castell. clatural changes is presented in Table 1. Unna and T. krusi Castell. Both were discussed by Nan- (1896) introduced two further Trichosporon spe- nizzi (1934). No authentic material is known to be cies from cases of white piedra. T. ovale Unna preserved of these species. They were treated as of originated from a European case and was charac- doubtful identity by Dodge (1935) and do Carmo- terized by relatively small cellular dimensions, Sousa (1970). while the fungus from Colombian white piedra, In 1909, de Beurmann & Gougerot introduced a described as T. giganteum Unna, had larger cells. species from a pruritic skin wound as Oidium cuta- No material is known to be preserved of either neum de Beurmann, Gougerot & Vaucher; the species. species was descibed in more detail by de Beur- Vuillemin (1902) treated all species as variants of mann et al. (1910). In contrast to the piedra isolates a single, variable species, referred to as Trichospo- mentioned above, this fungus was described as be- ton beigelii (Kiichenm. & Rabenh.) Vuill. Vuille- ing dimorphic: moist colonies consisting of mere min (1901) had earlier introduced the generic name budding cells could be converted into hyphal colo- Trichosporum Vuill., an illegitimate homonym of nies, and vice versa. Old cultures consisted mainly Trichosporum D. Don (Don 1822) and Trichospo- of hyphae which disarticulated with reluctance. rum Fr. (Fries 1825). Vuillemin's material prob- CBS 2466 is generally treated as a strain derived

Table 1. Chronology of names for Trichosporon species discussed in the text.

Name Author & year Source Remarks

Pleurococcus beigelii K~chenmeister & Human piedra Neotype CBS 7556 Rabenhorst 1867 Trichosporon ovale Behrend 1890 Human piedra Type lost Trichosporon ovale Unna 1896 Human piedra Type lost Trichosporon giganteum Unna 1896 Human piedra Type lost Trichosporon beigelii* (Kiichenm. & Rabenh.) Vuillemin 1902 Trichosporon foxi Castellani 1908 Human Piedra Type lost Trichosporon krusi Castellani 1908 Human Piedra Type lost Oidium cutaneum de Beurmann et al. 1909 Skin wound Type CBS 2466, = T. cutaneum Oospora granulosa Kambayashi 1922 Human piedra Type lost Oospora cerebriformis Kambayashi 1922 Human piedra Type lost Trichosporon equinum Fambach 1926 Animal piedra Type lost Trichosporon cutaneum* (de Beurmann et al.) Ota 1926 Trichosporon granulosum* (Kambayashi) Ota 1928 Trichosporon cerebriforme* (Kambayashi) Ota 1928 Trichosporon humahuaquense Mazza & Nifio 1933 Human piedra Type lost Trichosporon minus de Ar6a Le~o 1940 Human Piedra Type CBS 2480, = T. cutaneum

* New combinations of earlier described taxa. 287 from the type; a dried specimen is available at CBS. neum were too remote to be caused by one and the Diddens & Lodder (1942) were somewhat uncer- same fungus. Nevertheless, the influential opinion tain about its origin. It originated from M. Lange- of Diddens & Lodder was accepted Iongtime ron who worked at the Sabouraud collection at the (Kreger-van Rij, 1984). Medical Faculty at Paris, France; this is the same A recent revision of Trichosporon (Gu6ho et al. institute where de Beurmann studied his isolate. 1992) has presented a new insight into the taxono- Hence it is quite likely that an authentic strain was my of Trichosporon. The view that the genus con- concerned. A careful comparison of morphological sists of only a few, variable and ubiquitous species and cultural characters of CBS 2466 (= ATCC can no longer be upheld. On the contrary, a large 28592) with the authentic descriptions shows an series of species should be recognized which have exact correspondence in all respects. A dried speci- marked ecological preferences, such as human pu- men at CBS is here designated as neotype of Oidi- bic hairs (T. inkin) as opposed to growing on capital um cutaneum; CBS 2466 is derived from this type. hair (T. ovoides) or in association with animals (T. The species Oidium cutaneum has been trans- gracile). Strains isolated from humans belong to ferred to Trichosporon by Ota (1926). Since the other species than the ones found in soil and water. creation of the var. infestans (Moses & Vianna) The same authors unambiguously proved that the Diddens & Lodder (1942), the taxon is named Tri- isolates which in older literature were combined chosporon cutaneum (de Beurm. et al.) Ota var. under either the name T. beigelii or under T. cuta- cutaneum. neum were clearly different in their ubiquinone Kambayashi (1922) described Oospora granulo- systems and mole% G+C of DNA. sa Kambayashi and O. cerebriformis Kambayashi, agents of human white piedra, from Japan, which were later transferred to Trichosporon by Ota Conclusion (1928). Of neither species material has been preserved; they are of doubtful identity. The same Neotypification of the generic type species cannot holds for T. equinum Fambach (1926), described be based on a random selection of a strain that from nodules on horse hairs, thus representing the differs significantly from the protologue. Unfortu- only described species causing white piedra on nately, the original publication of Pleurococcus other mammals than humans. beigelii (Rabenhorst, 1867) concerned a very poor- Two further South American piedra species ly described specimen. We therefore must rely up- were described: T. humahuaquense Mazza & Nifio on the precise and adequate description given by (1933) and T. minus de Ar6a Lefio (1940). Material Behrend (1890) when introducing the genus Tri- of the former species was lost, while the latter chosporon with T. ovoides. His specimen belonged species, typified by CBS 2480 proved to be identi- to one of the taxa causing facial white piedra. Sig- cal with the earlier described T. cutaneum (Gu6ho nificant characters in his description are particular- et al. 1992). ly the moist initial growth, the subsequent devel- The conviction that Trichosporon cutaneum is opment of a farinose, snow-white covering and the synonymous to T beigelii and the absence of type star-shaped colony appearance due to submerged material of earlier published epithets led Diddens advancing hyphae. Strain CBS 7556 isolated from a & Lodder (1942) to accept Trichosporon cutaneum Caucasian with capital white piedra (Lasagni & (de Beurm. et al.) Ota as the oldest available name Ermacora 1977) exactly corresponds with the strain for the type species of the genus Trichosporon. Behrend (1890) described as T. ovoides and is They considered the ecological differences be- therefore designated as neotype (dried in herbari- tween T. cutaneum and T. beigelii, stressed earlier um CBS, Baarn) of Trichosporon ovoides. by Puntoni (1938), as insignificant. This decision Recently McPartland & Goff (1991) indicated was contested e.g. by Langeron (1945), who stated ATCC 28592 (= CBS 2466, selected above as neo- that the clinical pictures of T. beigelii and T cuta- type of T. cutaneum), as neotype of T. beigelii. The 288 authors maintained a broad concept of that species, Dodge CW (1935) Medical Mycology. C.V. Mosby Co., St. i.e. with the inclusion of T. cutaneum. Now that we Louis Don D (1822) Descriptions of two new genera of Nepal plants. know that two different species are concerned, the Edinb. philos. J. 7:82-86 neotype specimen must be in accordance with the Fambach D (1926) Trichosporum equinum. Z. Infektion- protologue of T. beigelii. CBS 2466 originated from skrankh. Haustiere 29:124-142 a subcutaneous lesion, while T. beigelii was de- Farr ER, Leussink JA & Stafleu FA (Eds) (1979) Index nomi- scribed from a case of white piedra. Consequently num genericorum (Plantarum), Vol. III: Pegaephyton-Syzy- gium. Regn. veg. 102:1277-1896 the neotypification proposed by McPartland & Fries EM (1825) Systema orbis vegetabilis. Lurid Goff (1991) is in conflict with Article 8.1(b) of the Greuter W (Ed) International Code of Botanical Nomencla- International Code of Botanical Nomenclature ture. Koeltz, K6nigstein Greuter 1988) and must therefore be rejected. Gu6ho E, Smith MTh, Hoog GS de, Billon-Grand G, Christen R & Batenburg-van der Vegte WH (1992) Contributions to a revision of the genus Trichosporon. Antonie van Leeuwen- hoek 61:289-316 (this issue) Acknowledgement Juhel-R6noy E (1888) De la Trichomycose nodulaire. Ann. Derm. Syph. 2:777-785 Prof. Ch. de Vroey (Antwerpen) is thanked for Kambayashi T (1922) Erreger der Piedrakrankheit in Japan. donating a subculture of strain CBS 7556 (= RV Jap. J. Dermatol. Urol. 23:483--511 Kreger-van Rij NJW (1984) Trichosporon Behrend. In: Kreger- 34067). van Rij NJW (Ed): The Yeasts, a Taxonomic Study (pp 933--962) Elsevier, Amsterdam Langeron M (1945) Pr6cis de mycologie. Masson, Paris References Lasagni A & Ermacora E (1977) Su un caso di piedra blanca in Lombardia. Giorn. Min. Dermatol. 112:241-243 Mazza S & Nifio FL (1933) Trichosporum posiblemente de n. Ar6a Legio AE de (1940) Considera~6es sobre os Thallospora- sp. Ren. Soc. Argent. Patol. Reg. Santiago 1:293-317 dos. O g6nero Trichosporon. 'Trichosporon minor' n. sp. McPartland J M & Golf JP (1991) Neotypification of Trichospo- produtor da piedra axilar. Mem. Inst. 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