PERSOONIA Published by the Rijksherbarium, Leiden Part. Volume 7, 3, 367-375 (1973) The genera Petriellidium and Pithoascus (Microascaceae) J.A. von Arx Centraalbureau The Netherlands voor Schimmelcultures, Baarn, the and the of Keys are given to genera of the Microascaceae to species Petriellidium and Pithoascus. In Petriellidium six species are accepted, P. desertorum, P. ellipsoideum, P. fusoideum, and P. africanum are described as new. In Pithoascus also six species are enumerated, P. platysporus and P. stoveri are the described as new, for Microascus exsertus Skou combination Pithoascus exsertus is proposed. Introduction The family Microascaceae, covering five genera of ascomycetes, has been treated by for Malloch (1970). Microascus, Petriella and Lophotrichus are accepted species with non-ostiolate classifiedin Kerniaand the ostiolateascomata; the counterparts are new Petriellidium. A further Pithoascus has been Arx genus genus proposed by von (1973) for some species hitherto classified in Microascus. The Microascaceae be the characteristics ofthe can easily recognized by ascospores, which are one-celled, smooth, relatively small, yellowish, straw coloured, reddish or dextrinoid when and with often indistinct copper coloured, young, an or inconspi- both ends. The formationof conidia is characteristic in of cuous germ pore at most the genera. Typical Microascus and Kernia species include a Scopulariopsis or War- have like conidial domyces conidialstate; all Petriella species a Graphium- state, and in ali Petriellidium and oftenalso conidial is species a Scedosporium- a Graphium- state present. No conidial states are known in Lophotrichus- and Pithoascus-species. The latter genus also be the slow of the colonies and can recognized by very growth by glabrous which be ostiolate non-ostiolate. ascomata, may or related the The Microascaceae are a natural family, to Melanosporaceae. The the genus Lophotrichus is in some respects intermediate, especially species L. incarnatus Seth with bright ascomata and larger ascospores points to Melanospora, Corynascus and other genera with elongated, smooth ascospores with 2 prominent germ pores. A number of cultures of Microascaceae have become available recently to the author. Some of them could not be identified with any described taxon, but can be and and will be described classified within the genera Petriellidium Pithoascus below. KEY TO THE GENERA coloured and without 1. Conidialstates absent; ascospores usually yellowish or straw observable germ pores 2 367 PERSOONIA- Part 368 Vol. 7, 3, 1973 1. Conidialstates usually present (from genera Scopulariopsis, Wardomyces, Graphium,Scedosporium and reddish with often others), ascospores yellowish, or copper coloured, inconspicuous germ pores 3 Ascomata 2. discrete, usually ostiolate, especially apically setose or hairy; ascospores usually symmetrical; colonies spreading Lophotrichus form dense 2. Ascomata often crusts, black, glabrous, often non-ostiolate; ascospores usually in Pithoascus narrow, colonies very restricted growth or or straw shorter than 6 3- Ascospores reniform, triangular ellipsoidal, yellow coloured, fim; conidial is or state Scopulariopsis Wardomyces 4 than 6 3- Ascospores usually ellipsoidal or broadly fusiform, longer (iin, yellow or reddish, conidial state usually is Graphium and/or Scedosporium 5 Ascomata 4- ostiolate; ascospores usually asymmetrical Microascus Ascomata with 4- non-ostiolate, usually appendages; ascospores symmetrical or asymmetrical Kernia Ascomata often reddish or 5- ostiolate, setose, ascospores copper coloured, usually asymme- trical Petriella Ascomata with a small 5. non-ostiolate, rarely ostiolum, usually submerged, ascospores yellowish or straw coloured, rarely reddish, usually symmetrical or nearly so Petriellidium The Microascus and Petriella have been treated genera by Barron & al. (1961a, b), Kernia was studied by Malloch & Cain (1971), Lophotrichus by Seth (1971) (compare also Malloch, 1970). The distinction of Lophotrichus and Kernia, however, is not yet defined! The and satisfactorily genera Petriellidium Pithoascus will be treated in the following. PETRIELLIDIUM Malloch Malloch in — P. Mal- Petriellidium Mycologia 62: 738. 1970. Type species: boydii (Shear) loch (= Allescheria boydii Shear). KEY TO THE SPECIES about catenulate P. I. Ascospores 12X9ftm, conidia often desertorum wide 1. Ascospores usually 3-6 fim 2 about 8 P. 2. Ascospores ellipsoidal, x 5 fim ellipsoideum about smaller 2. Ascospores 7x4 /un or 3 Brownish conidia in 180 3. (chlamydospores) present, 7-12 X 4-7 fim size, ascomata up to fim in P. diameter, ascospores 6-7 X 3.5-4/'m boydii Conidia coloured 3- smaller, yellowish, straw or hyaline 4 attenuated both in 4. Ascospores fusiform, at ends; 6-8x3-4/mi; ascomata 50-100 /jm diameter; conidia usually borne in synnemata P. fusoideum with rounded absent 4. Ascospores ellipsoidal, ends; synnemata usually 5 about conidia in diameter 5. Ascospores 6x4 /im; hyaline, 4-5x3 (im; ascomata 50-90 (im ...........P. africanum about conidia 5. Ascospores narrow, 7x3.5 /im; clavate, 6-10x4 //m; ascomata up to in P. 150 n m diameter, dark, covered with hyphae angustum VON ARX: Petriellidium and Pithoascus 369 1. PETRIELLIDIUM BOYDII (Shear) Malloch Allescheria Shear in — Malloch boydii Mycologia 14: 242. 1922. Petriellidium boydii (Shear) in Mycologia 62: 738. 1970. CONIDIAL STATE.—Scedosporium apiospermum (Sacc.) Sacc. Monosporium apiospermum Sacc. in Annls mycol. 9: 254. 191 1. — Scedosporium apiospermum Sacc. (Sacc.) (1914, sensu Dodge, 1935; not validly published). Colonies on oat-meal agar with a daily growth rate of 4-5 mm at 25°C, at first whitish floccose later with brown or greyish, or lanose, grey or shades; ascomata spherical, non-ostiolate, usually submerged, I4O-20O /urn in diam., often covered with wide with 4—6 thick brown, thick-walled, septate, 2-3 /un hyphae, a /im wall, composed of 2-3 layers of meandrically interwoven, flattened, 2-6 /xm wide, dark brown cells asci 12-18 hyphal ; ellipsoidal or nearly spherical, x 9-13 /<m, evanescent, straw 8-spored; ascospores ellipsoidal, symmetrical or slightly flattened, coloured, with conidia of conidia 2 germ pores, 6-6.5(~7) X 3.5—4 <um; 2 types: 1) Sce- clavate rounded the dosporium apiospermum (Sacc.) Sacc.] broadly or ovoidal, above, at base and with brown 6-12 attenuated truncate, a rather thick, wall, X 3.5-6 /mi, borne terminally or laterally on solitary conidiogenous hyphae, chlamydospore- conidia clavate the like; 2) or nearly cylindrical, truncate at base, hyaline, 5-7 X borne in short which 2-3 fim, sympodulae on elongating conidiogenous cells, usually arise in erect synnemata. The above description is based on CBS 254.66, isolated from savannah soil, L. Renard. In CBS the Abidjan, Africa, by J. 101.22, type culture, only Scedosporium- could CBS chlamydospores be observed, 7-14x4-6 /im in size. In 593.73, recently isolated from soil from Surinam H. Emden by J. van some erumpent ascomata showed the formation of and the an apical papilla (an ostiolum) ascospores were and extruded through the pore in a droplet. Size and shape of ascomata, ascospores chlamydospores, however, indicate the identity of this strain with Petriellidium boydii. 2. PETRIELLIDIUM ANGUSTUM Malloch & Cain Petriellidium Malloch & Cain in Can. Bot. angustum J. 50: 66. 1972. Colonies oat-meal with of first on agar a daily growth rate 4-5 mm at 24°C., at whitish and lanose by the development of aerial hyphae, soon becoming dark by abundant formation of ascomata; ascomata spherical, non-ostiolate, dark brown, in often covered with dark with 100-150 71m diam., usually submerged, hyphae, a 4-6 thick of interwoven brownish 71m wall, composed of 2-3 layers flattened, hyphal asci i4—18 8-10 cells; ellipsoidal or nearly spherical, evanescent, 8-spored, X 7*m; ascospores narrowly ellipsoidal or nearly cylindrical with rounded ends, with 2 indistinct first straw-coloured germ pores, at hyaline, or yellowish, 6-7 X 3-3.8 /am; conidia clavate or nearly cylindrical, rounded above, truncate at the base, hyaline, 5-10 X 3-4.5 ,«m, borne singly on short hyphal branches or in small sympodulae. TYPE. —CBS 254.72=TRTC 45321, isolated from sewage half digestion tank, Deyton, USA. PERSOONIA Vol. Part 370 7, 3, 1973 This species is very close to P. boydii; it can be distinguished by a more abundant of and the absence of production ascomata, by narrow ascospores by brown, chlamy- dospore-like conidia. Only a few conidia could be observed in sub-cultures of the type. 3. Petriellidiumafricanum v. Arx & Franz, spec. nov. Coloniaein farina addita in diebus agaro maydis 24°C 3-3.5 mm crescunt; primum hyalinae, aerium deinde fuscae; mycelium sparsum; ascomata plerumque submersa, sphaerica, non intertextis ostiolata, fusca, 50-90 /im diam., pariete 7-11 /im e cellulis hyphalibus applanatis, asci late composito; ellipsoidei, evanescentes, 13-17 X 12-15//m; ascosporae ellipsoideae, dilute duobus distalibus luteae, continuae, poris germinationis praeditae, 5.5-7 X 3.5-4.5/tm; conidia clavata vel cellulis ellipsoidea, continua, hyalina, 4-5 X 2.5-3.5 /im e conidiogenis oriunda cicatrices ducentia. CBS isolatus terra sympodialiter elongatis Typus: 311.72, e in arenosa, Tsiutsabis Africa austro-occidentali. Colonies oat-meal with of first on agar a daily growth rate 3-3.5 mm at 24°C, at light greyish, later with some darker shades, flat; superficial mycelium sparse, of wide composed branched, septate, hyaline or brownish, 2-4 /xm hyphae; ascomata blackish spherical, non-ostiolate, submerged or nearly superficial, brown, 50-90 71m in with thick wall of of inter- diameter, a 7-1 1 composed 2-3 layers irregularly wide cells of 6-1 wide asci woven, flattened, brown, 3-6 /xm hyphal or 1 /xm cells; ellipsoidal or nearly spherical, evanescent, 8-spored, 13—17 X 12-15 /xm; ascospores often with rounded ends with broadly ellipsoidal, inequilateral, 2 germ pores, yellowish or golden brownish, 5.5-7 X 3-5—4.5 /xm (usually (6x4 /xm) ; conidia of one type, ellipsoidal or nearly clavate, broadly rounded above, at the base rounded or slightly truncate, i-celled, hyaline, 4—5 X 2.5-3.5 /xm, with 2 or 3 refractive borne at bubbles, the top of sympodially elongating cells.