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 / 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 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. TYPE.—CBS 311.72, isolated by G.Franz from sandy soil, South Western Africa, Tsiutsabis, sent for identification (No. 105). This species resembles P. angustum, but differs by smaller conidia, wider but and shorter ascospores smaller ascomata. Petriellidium Arx & 4. ellipsoideum v. Fassatiová, spec. nov. Coloniae in addita in agaro farina maydis 24°C diebus 2.5-3 mm crescunt; primum albidae, floccosae vel lanosae, deinde griseolae vel rubro-brunneae ; ascomata vulgo submersa,sphaerica, cellulis nonostiolata, brunnea,75-180 /jm diam., pariete4-7 fim crasso e hyphalibusrubrobrun- intertextis neis, applanatis, irregulariter composito; asci ellipsoidei, evanescentes, 8-spori, duobus 15-23 X 14-18 /xm; ascosporae ellipsoideae, stramineae, poris germinationis praedi- conidia clavata vel vel dilute tae, 7-9x5-6 /um; cylindrica, utrinque truncata, hyalina flava, CBS isolatus in Tadzhikistanis ab O. Fassatiovä. 6-9X3-3-5 /xm. Typus: 418.73, e terra Colonies oat-meal with of at first on agar a daily growth rate 2.5-3 mrn at 2 4°C, whitish or greyish with a floccose or lanose aerial mycelium, later becoming greyish or reddish brown; ascomata immersed or semi-immersed, spherical, glabrous or covered with loose in with hyphae, non-ostiolate, brown, 75-180 /im diameter, a 4—7 y«m thick wall composed of irregularly interwoven, flattened, reddish-brown, thin-walled asci cells, 7-15 X 3-6 yum in size; ellipsoidal or spherical, very evanes- I4-I8 CENTI 8-spored, 15-23 X /xm; ascospores broadly ellipsoidal, mostly symmet- rical, rounded at both ends, brightly straw coloured, with 2 germ pores, 7-9 X VON ARX: Petriellidium and Pithoascus 371 5-6 /im; conidia borne on superficial hyphae or on short lateral branches, clavate or nearly cylindrical, with a truncate base, hyaline or straw coloured, thin-walled, 6-9 X 3-5-5 j"m- TYPE.—CBS 418.73, isolated from soil, Tadzhikistan, USSR, sent for identifica- tion by O. Fassatiova (Tn). This species is close to P. boydii, but differs by larger ascospores and smaller conidia. 5. Petriellidiumfusoideum v. Arx, spec. nov. in in Coloniae agaro farina maydis addita24°C diebus 2.5-3 mm crescunt; primum albidae, deinde viridibrunneae, floccosae; ascomata submersa, sphaerica, fusca, non ostiolata, 50-100 cellulis /im diam., pariete e hyphalibus applanatis, intertextis composita; asci ellipsoidei, duobus 8-spori, evanescentes, 12-15X10-12 fim, ascosporae fusiformes, stramineae, poris germinationis praeditae, 6-7.5 x 3-5-4 ftm; conidia modo Scedosporii formata clavata, basi dilute lutea vel lateralia vel terminalia truncata, hyalina, 5—10 X 3-5 //m, e hyphis oriunda; conidia modo Graphii formata basi hyalina, X xm e cellulis clavata, truncata, 4-7 2.5-3.5 l > conidiogenis sympodialiter elongatis cicatricibus relictis verticillatis in synnematibus dispositis. CBS isolatus Typus: 106.53, e terra in Panama a L. Ajello. rate at at Colonies on oat-meal with a daily growth 24°C of mm first agar 2.5-3 ; of whitish, soon becoming greyish, greenish or brownish; mycelium composed wide ascomata branched, septate, hyaline or brownish, /im hyphae ; submerged Vior vior darkiv ill oviiu-iiiiiiiviovu,semi-immersed, spherical nearlyiivany so,ow, non-ostiolate,uvu-vouviaiv, brown,VIVVYU, 50-100nv-ivv /urna*XXX with 4-6 thick of of meandri- diameter, a /urn wall, composed 2-3 layers flattened, wide asci cally interwoven, brown, 3-5 /«m hyphal cells; ellipsoidal or nearly spher- ical, evanescent, 8-spored, 12-15 X 10-12 /im; ascospores broadly fusiform, atten- uated at both with distal x ends, yellowish or straw-coloured, 2 germ pores, 6-7.5 of conidia formed: rounded 3. um; 2 types are Scedosporium conidia clavate, above, truncate at the 6-10 X borne base, yellowish or nearly hyaline, 3.5-5 /un, the laterally on hyphae or terminally on short hyphal branches, separated by a conidia truncate at the septum; Graphium clavate, base, hyaline, \~1 X 2.5-3.5 /im, borneon wide 1.5-2 /urn scars on sympodially elongating, 10-18 / TYPE.—CBS 106.53, isolated from soil, Panama, in 1953 sent to CBS by L. Ajello (as Allescheria boydii). Petriellidiumboydii differs from P.fusoideum by much larger ascomata, by ellipsoidal ascospores and by larger and pigmented Scedosporium- conidia. 6. Petriellidiumdesertorum Arx v. & Moustafa, spec. nov. Coloniae in farina addita diebus agaro maydis 24°C in circa 3 mm crescunt; primum albidae, tomentosae vel floccosae, deinde griseo-brunneae; ascomata submersa vel fere 80-100 tenui cellularum superficialia, non ostiolata, //m diam., pariete e strato hyphalium intertextarum asci composito; sphaerici, 8-spori, evanescentes, 25-30 //m diam.; ascosporae ellipsoideae, primum hyalinae, dextrinoideae, maturitate aeri cyprio similiter coloratae, duobus conidia breviter poris germinationis inconspicuis praeditae, 11-14x7.5-10 /um; vel vel successione cylindrica clavata, hyalina, 4-8 X 3-4.5 j«m, singula catenata, basipetali formata. fragmentatione Typus: CBS 489.72, isolatus ex arena salina in Kuwait ab A. F. Moustafa. PERSOONIA Vol. Part 372 7, 3, 1973 Colonies on oat-meal agar with a daily growth rate ofabout 3 mm at 24°C, at first floccose aerial later brown whitish, due to a tomentose or mycelium, greyish ; hyphae hyaline or yellowish, septate, 3-5 wide; ascomata spherical, non-ostiolate, submerg- ed or nearly superficial, 8o-no/miin diameter, withathinwall composed ofalayerof reddish wide irregularly interwoven, flattened, light greenish or brown, 3-5 um hyphal cells; asci spherical or ellipsoidal, evanescent, 25-30 um in diameter; first reddish brown coloured ascospores ellipsoidal, at hyaline, dextrinoid, or copper when ripe, with a thick wall and 2 indistinct germ pores, 11 — 14 X 7.5-10 /un in conidia short 4-8 size; (arthroconidia) cylindrical or clavate, hyaline, X 3-4-5 /urn, borne singly or in chains in basipetal succession on the hyphae or on integrated cylindrical conidiogenous cells fragmenting to form the conidia. TYPE. —CBS 489.72, isolated from salt marsh soil in Kuwait by A. F. Moustafa, sent for identification(Nr.44). This others the species differsfrom all by its larger, especially wider ascospores, by thin of the wall ascomata and by a deviating conidial state with usually catenulate conidia. PITHOASCUS v. Arx Arx in Proc. K. Wet. — P. Pithoascus v. Ned. Akad. (C) 76: 295. 1973. Type species: nidicola (Massee & Salmon) v. Arx=Microascus nidicola Massee & Salmon. KEY TO THE SPECIES reddish about P. I. Ascospores broadly ellipsoidal, brown, 7X5 /im platysporus than 1. Ascospores less 4 fim wide, yellowish 2 2. Ascospores 8-12 /«n long 3 2. Ascospores 5-8 //m long 4 P. 3. Ascospores 3-4 /tm wide, ascomata ostiolate schumacheri non-ostiolate P. exsertus 3- Ascospores 1.5-2 /um wide, ascomata usually ostiolate P. intermedius 4. Ascospores 5-6x2-2.7 /jm, ascomata 4- Ascospores 6-8 /im long 5 Ascomata in diameter P. nidicola 5. usually ostiolate, 90-160 /im in P. stoveri 5- Ascomata non-ostiolate, 50-110 /um diameter PITHOASCUS Arx 1. NIDICOLA (Massee & Salmon) v. Massee & Salmon Ann. — Pithoascus nidicola Microascus nidicola in Bot., Lond. 15: 313. 1901. & Arx in Proc. K. Ned. Akad. Wet. (Massee Salmon) v. (C) 76: 292. 1973. Colonies on oat-mealagar withrestricted growth, daily rate at 24°C about 1 .5 mm, first whitish dark the at or light greyish, flat, without aerial mycelium, becoming by of the immersed m production ascomata; hyphae hyaline, septate, 1.5-3 <" wide; ascomata aggregated, often confluent or forming glabrous crusts, black, spherical or in with wide obovate, 90-160 /im diameter, apically papillate, a 15-20 yum pore, surrounded dark-walled wall of the ascomata 6-10 of by cells; fim thick, composed a asci pseudoparenchyma ofbrown, flattened, 4—8 //m wide cells; ellipsoidal or barrel- in vertical shaped, arranged rows, 10-15x7-12 /um, 8-spored, evanescent; ascospor- es navicular or nearly lunate, asymmetrical, often plano-convex, straw coloured or nearly hyaline, 6-8 X 2-2.5 ("M - ARX: Petriellidium and Pithoascus VON 373 The description is based on CBS 197.61 =IMI 86,918, isolated by C. W. Emmons from Dipodomys merriami. Pithoascus stoveri 2. v. Arx, spec. nov. in °C in diebus minus Coloniae agaro farina maydis addita 24 quam 1 mm crescunt; hyalinae, hyphae praecipue submersae; ascomata partim submersa, aggregata, saepe crustosa, vel tribus sphaerica, glabra, non ostiolata, nigrescentia, 50-110 //m diam., pariete e duobus stratis cellularum fuscitunicatarum, applanatarumcomposito; asci ellipsoidei, 8-spori, evanes- m Status centes, 11-15 X 7-10 / non visus. Typus: CBS 176.71, isolatus e radicibus betae a W. L. White. Colonies oat-meal with rate of less on agar growing restrictedly, a daily growth than of 1 mm at 24°C, consisting mainly immersed, hyaline or greyish hyphae, at first light greyish, flat, without aerial mycelium, later becoming dark due to the densely aggregated ascomata, which ripen within 6-8 weeks; ascomata basally with the immersed, becoming superficial upper part, rarely discrete, usually aggre- gated into dark crusts, spherical, non-ostiolate, glabrous, blackish brown, 50-1 10 /tm in with a thick of of flattened, dark- diameter, 4-7 /im wall, composed 2-3 layers walled cells, 4-7 /im in size; asci ellipsoidal or barrel-shaped, broadly roundedabove, at the base often in slightly attenuated, 8-spored, evanescent, 11-15 X 7-10 fim size; ascospores reniform, planoconvex, attenuated at both ends, straw coloured or indistinct. golden brownish, 6-7.5 x 2-3> usually 7x2.5 fin 1 in size, germ pores TYPE.—CBS isolated from of beet i76.7i=ATCC 11173, roots sugar seedlings by W. L. White, received as Papulaspora stoveri Warren. Pithoascus stoveri is close to P. nidicola, but can be distinguished by smaller, non- ostiolate and shorter but wider ascomata by relatively ascospores. PITHOASCUS Arx 3. INTERMEDIUS (Emmons & Dodge) v. intermedius Emmons & in — Pithoascus Microascus Dodge Mycologia 23: 313. 1931. intermedius & Arx in Proc. K. Ned. Akad. Wet. (Emmons Dodge) v. (C) 76: 292. 1973. Colonies oat-meal with rate of less than on agar restricted, a daily growth 1 mm at 25°C, flat, at first whitish, becoming dark by the formationoftheascomata, mycelium in usually submerged; ascomata semi-immersed or nearly superficial, aggregated dense with short often curved crusts, spherical, a cylindrical, ostiolum, rarely non- in with 6-8 thick wall ostiolate, glabrous, black, 95-150 fim diam., a /im composed of of asci a pseudoparenchyma flattened, greenish black, 4-8 /im sized cells; formed in vertical rows, broadly clavate or barrel-shaped, above broadly rounded, evanes- cent, 8-spored, 10-15 X 6-9 / X m 5-6 2-2.5 /" - The is based CBS = IMI isolated description on 217.32 86,917 (type strain), by B. O. Dodge from roots of Fragaria vesca. CBS 542.72, received from J. P. Skou, isolated in from Osmia and have the W-Germany spec, CBS 1 69.73 =NRRL same characters. Pithoascus comb. 4. exsertus (Skou) v. Arx, nov. Microascus in Antonie exsertus Skou van Leeuwenhoek 39: 529. 1973 (basionym). PERSOONIA —• Vol. Part 374 7, 3, 1973 This species has been described in detail by Skou (1973). The wall of the spherical is thinner in the umbilicate here late with ascomata upper part and opens in a state ostiolar The asci in vertical and an irregular pore. barrel-shaped are arranged rows contain 8 fasciculate ascospores, cylindrical-navicular, yellowish, Germ pores could not be observed with certainty. CBS the isolated from in 819.70 was studied, type strain, Megachile willughbiella Denmark. 5. PITHOASCUS SCHUMACHERI (Hansen) v. Arx schumacheri Foren. — Sphaerella Hansen in Vid. Meddr. dansk naturh. 1876: 37. 1877. Rosellinia — schumacheri (Hansen) Sacc., Syll. Fung. 1: 276. 1882. Microascus schumacheri in Boll. Patol. Roma 60. — (Hansen) Curzi Staz. veg., 11: 193 1. Pithoascus schumacheri (Hansen) Arx in Proc. K. Wet. v. Ned. Akad. (C) 76: 292. 1973. No cultures ofthis species were available. It has been described in detail by Barron & al. (1961b). 6. Pithoascus platysporus v. Arx & Veenbaas-Rijks, spec. nov. in farina addita in Coloniae agaro maydis 25 °C diebus minus quam 1 mm crescunt; dilute griseae, e hyphis praecipue immersis constant; ascomata partim submersa, acervata, crustas fuscas formant, sphaerica, nigra, glabra,plerumque non ostiolata, 100-240 fim diam., pariete crasso e tribus ad quattuor stratis cellularum fuscarum applanatarum composito; asci ellip- vel soidei, 8-spori, evanescentes, 15-20 x 12-18 / conidialis W. non visus. Typus: CBS 419.73, isolatus e terra agresti, Wageningen,a J. Veenbaas- Rijks. Colonies than on oat-meal agar with restricted growth, daily rate at 25°C less of immersed i mm, bright greyish or nearly colourless, consisting mainly hyphae, composed of 2.5-5 wide, thick-walled, hyaline, often swollen cells; later becoming ascomata yellowish by development of some aerial hyphae or black by formation of ; ascomata in the basally immersed, becoming superficial upper part, crowded, forming dense crusts, spherical, black, glabrous, IOO-24O /im in diameter, usually non- with thick ostiolate, rarely an inconspicuous ostiolar pore, with a 12-16 /un wall, of of wide cells asci composed 3-4 layers dark, flattened, 5-9 /im ; ellipsoidal, evanes- cent, 8-spored, 15-20 X 12-18 /un; ascospores broadly ellipsoidal or ovoidal, sym- metrical flattened reddish brown or slightly at one side, thick-walled, or copper coloured, without germ pores, 6-9 X 4.5-6.5 / This species differs from all others by its reddish-brown, broadly ellipsoidal ascospores. REFERENCES ARX, J. A. VON (1973). Ostiolate and non-ostiolate Pyrenomycetes. In Proc. K. Ned. Akad. Wet. (C) 76: 289-296. VON ARX : Petriellidium and Pithoascus 375 G. R. F. & C. A revision of the Petriella. In BARRON, L., CAIN, GILMAN, J. (1961a). genus Can. Bot. J. 39: 837-845. & The Microascus. In Can. Bot. , (1961b). genus J. 39: 1609-1631. MALLOCH, D. (1970). New concepts in the Microascaceae illustrated by two new species. In 6a: Mycologia 727-740. & R. F. The In Can. Bot. CAIN, (1971). genus Kernia. J. 49: 855-867. In Nova SETH, H. K. (1971). The genus Lophotrichus. Hedwigia 19: 591-599 ("197°"). """ leaf SKOU, J. P., (1973). Microascus exsertus sp. nov., associated with a cutting bee, with con- siderations of in the Zukal. In Antonie on relationships species genus Microascus van Leeuwenhoek 39 : 529-538.