occasional papers of the

Farlow.
Herbarium of cryptogamic botany

No.8 May, 1975 Harvard University, Cambridge, Massachusetts

The Genus Acervus (Ascomycetes, Pezizales)

Donald H. Pfister | |. An Emendation =
ll. The Apothecial Ontofigeny of Acervus flavidus with
Comments on A. epispartius

Edited by: Reed C. Rollins
Kathryn Roby

occasional papers of the

Farlow.
HerbariuM of cryptogamic botany

No. 1. Sylvia A. Earle: Hummbrella, a New Red Alga of Uncertain Tax-

No.

No.

No.

No.

No.

No.

No.

onomic Position from the Juan Fernandez Islands (June 1969).

. |. Mackenzie Lamb: Stereocaulon arenarium (Sav.) M. Lamb, a

Hitherto Overlooked Boreal-Arctic Lichen (June 1972).

. Sylvia A. Earle and Joyce Redemsky Young: Siphonociathrus, a

New Genus of Chlorophyta (Siphonales: Codiaceae) from Panama
(July 1972).

. I. Mackenzie Lamb, William A. Weber, H. Martin Jahns, Siegfried

Huneck: Ca/athaspis, a New Genus of the Lichen Family Cladonia-
ceae (July 1972).

. 1. Mackenzie Lamb: Stereocau/on steri/e (Sav.) M. Lamb and Stereo-

caulon groenlandicum (Dahl) M. Lamb, Two More Hitherto Over-
looked Lichen Species (March 1973).

. I. Mackenzie Lamb: Further Observations on Verrucaria serpuloides

M. Lamb, the Only Known Permanently Submerged Marine Lichen
(April 1973).

. Bruce H. Tiffnmey and Elso S. Barghoorn: The Fossil Record of the

Fungi (June, 1974).

. Donald H. Pfister: The Genus Acervus (Ascomycetes, Pezizales).

|. An Emendation. Il. The Apothecial Ontomgeny of Acervus flavidus
with Comments on A. epispartius (May, 1975).

THE GENUS ACERVUS (ASCOMYCETES, PEZIZALES)!

DoNALD H. PFISTER

1. AN EMENDATION

SUMMARY

An emendation of the genus Acervus Kanouse is proposed, The genus, previously
monotypic, is considered to be an older name for Phaedropezia Le Gal. Two new
combinations are made: Acervus flavidus and A. epispartia. The latter is the older
epithet for A. aurantiacus, type of the genus Acercus. The histories of the two genera
are discussed, a key to the recognized species is given, and detailed notes for the
species are provided.

Stability in the Pezizalean generic nomenclature and circumscriptions
is the result of recent investigations by many workers. In his synthesis
of the order, Korf (1972) has summarized the work. Because generic
delimitations are now more perfectly defined, it is possible to study and
analyze poorly known genera. As a consequence, an occasional merger of
genera may be effected. A case in point involves the reexamination of
Acervus Kanouse and Phaedropezia Le Gal. The material studied in-
cludes holotypes, all available dried collections referred to either genus,
and fresh material from the West Indies.

The montotypie genus Acervus was erected by Kanouse (1938) upon a
single collection from Michigan which she named A. aurantiacus Kanouse.
This remained the only known collection until Gamundi (1970) reported
the species from Argentina. Kanouse considered the asci to be inopercu-
late and thus placed the genus in the Dermateaceae. Seaver (1951)
treated it in the Helotiaceae and placed it in the tribe Ascotremelleae.
From his study of the holotype Korf (1963) concluded that the asci were
suboperculate and treated the genus in the Sarcoseyphaceae. Korf (1972,
1973) later reconsidered his position and Acervus was placed in the
Pyronemataceae sensu Korf. Denison (1972) also treated Acervus in the
Sarcosyphaceae though he did not state his reasons. The genus was not
accepted by Eckblad (1968) who included it among the genera he con-
sidered to be insufficiently known.

Kanouse (1938), Korf (1963) and Gamundi (1970) gave detailed
descriptions of Acervus aurantiacus. Critical features are: (1) the small
size of the ascospores which rarely reach a length greater than 8 ym; (2)
the medullary excipulum which is composed of large diameter, inter-
woven hyphae with occasional swellings; (3) the ectal excipulum which,
though not clearly delimited from the medullary excipulum toward the
1Financial support for this work and its publication was provided, in part, by National Science
Foundation Grant GB-36162, “Floristic and Monographic Studies of Caribbean Discomycetes.’’

The author wishes to thank Dr, Richard P. Korf for reading the manuscript and offering his
suggestions.

1

ps DONALD H. PFISTER

inside, is differentiated into more or less closely packed textura angularis
toward the outer surface; (4) the bright yellow to orange paraphyses, the
pigments of which are soluble in water and alcohol.

Phaedropezia, the more recently established genus, was described by
Le Gal (1953). Under this genus she brought together a natural and
homogeneous group of species. Peziza epispartia Berk. & Br. was listed
as the type of the genus since it was considered by Le Gal to be the best
known and most adequately studied of the species. Psilopezia flavida
Berk. & Curt. was placed in the genus and Phaedropezia genuina Le Gal
was described as a new species. Later Peziza flavotingens Berk. & Br. also
was considered a distinct species of Phaedropezia (Le Gal 1959). Patou-
illard (1913) had considered the asci to be inoperculate in Peziza epis-
partia whereas, in her original account of Phaedropezia, Le Gal described
and illustrated the asci as suboperculate. Although she did not place the
genus in the Sarcoseyphaceae because of the apothecial anatomy and
concomitant fragile texture of the apothecia, both Eckblad (1968) and
Korf (1970) considered Phaedropezia to belong to that family.

Le Gal (1969) argued that Phaedropezia was not sarcoscyphaceous.
Cytological evidence substantiates her contention (Pfister 1972) since
ascospores are uninucleate rather than multinucleate as in the Sarcoscy-
phaceae. Korf (1972, 1973) placed Phaedropezia in the Pyronemataceae.

Comparative studies of the apothecial anatomy of the holotypes of
Acervus aurantiacus and Phaedropezia epispartia show that there is no
significant difference between the two specimens. The name Acervus,
being older, takes precedence over Phaedropezia. The genus Acervus as
now conceived is essentially identical in circumscription to Phaedropezia.
The excellent accounts by Le Gal, and her insight into the relationships
of these species, leave little to add descriptively.

The placement of the genus within the Pezizales remains problematic.
As indicated previously, the asci have been interpreted by various inves-
tigators as inoperculate, suboperculate, and operculate. In my studies of
the genus, I have not observed a true terminal operculum. The asci
dehisce by splitting apically, producing a lateral flap. This is not unlike
the bilabiate asci of Caccobius, Coprobolus, Trichobolus, Thelebolus,
and Ascozonus all of which have been treated as Pezizales. No apical
pad or thickening was observed. This, along with the structure of the
apothecium and the uninucleate condition of the ascospore, is considered
sufficient to warrant its placement in the Pezizineae. Ascospore discharge
is forcible. Le Gal (1969) established the tribe Sowerbyelleae of the
Pezizales in which she included Phaedropezia, Caloscypha, and Sower-
byella. She thought that both Sowerbyella and Phaedropezia would be
shown to have the same unique carotenoids which Arpin (1969) found in
Caloscypha, and believed the apothecial anatomy to be similar in all
three genera. Korf (1973) added Acervus to this tribe. This grouping is

THE GENUS ACERVUS ( ASCOMYCETES, PEZIZALES ) 3

tentatively accepted here, though not without hesitation. Pigments do
differ between Acervus and Caloscypha, at least in solubility. The pig-
ments in Acervus are easily and readily soluble in alcohol and in water to
some extent but those in Caloscypha are not significantly soluble in either
alcohol or in water. Studies of the carotenoids in members of these genera
and study of the ontogeny of the apothecia may add needed information
which might then allow more precise placement of this genus within the
order. Another possible solution to the problem of determining the rela-
tionships of Acervus was offered by Rifai (1968). He suggested that
Phaedropezia might require an additional family within the Pezizales.
Details of apothecial ontogeny outlined in part 2 of this paper do indicate
that Acervus might occupy an isolated position in the order. However,
erection of a new family is still premature.

ACERVUS Kanouse, emend. Pfister

= Acervus Kanouse, Pap. Michigan Acad. Sci. 23:149. 1938 (1937). TYPE: Acervus
aurantiacus Kanouse = Acervus epispartius (Berk. & Br.) Pfist.

= Phaedropezia Le Gal, Prodr. Flore Mycol. Madagascar 4:179. 1953. TYPE: Peziza
epispartia Berk. & Br.

KEY TO THE SPECIES

Spores 5.8-7.5(9) 3.2-4 wm, with relatively thin walls, spores blunt, spores regular

UE AO pre Se sakes x's «acd hahaa aw asa dale ow ata Acervus epispartius
Spores (7.5)9-13 % 5 X 5-7 um, with a thick wall, spores regularly ellipsoid to irreg-
ular in GULING wind weve seo Acervus flavidus (cfr. also Phaedropezia genuina)

1. Acervus epispartius ( Berk. & Br.) Pfister, comb. nov.

= Peziza epispartia Berk. & Br., J. Linn. Soc., Bot. 14:103. 1873.
= Phialea epispartia (Berk. & Br.) Pat., Bull. Soc. Mycol. France 29:221. 1913.
Phaedropezia epispartia (Berk. & Br.) Le Gal, Prodr. Flore Mycol. Madagascar
4:181. 1953.
= Peziza flavotingens Berk. & Br., J. Linn. Soc., Bot. 14: 104. 1873.
Humaria flavotingens (Berk. & Br.) Sacc., Syll. Fung. 8:129. 1889.
Phaedropezia flavotingens (Berk. & Br.) Le Gal, Bull. Jard. Bot. Etat 29:96.
1959,
=Pexziza radiculosa Berk. & Br., J. Linn. Soc., Bot. 14:103. 1873.
= Sarcoscypha radiculosa (Berk. & Br.) Sacc., Syll. Fung. 8:155. 1889.
= Peziza microspora Berk. & Curt. in Berk., Grevillea 3:150. 1875.
= Humaria microspora (Berk. & Curt. in Berk.) Sacc., Syll. Fung. 8:131. 1889.
= Acervus aurantiacus Kanouse, Pap. Michigan Acad. Sci. 23:149. 1938 (1937).

Ill |

Hil Il

Acervus epispartius has been fully described by several authors
(Kanouse 1937, Le Gal 1953, Korf 1963). The specific epithet was mis-
spelled by Cooke in the Mycographia where it appeared as Peziza epi-
sparticus.

Three epithets in the synonymy date from the same publication and

4 DONALD H. PFISTER

were based on collections made at Peradeniya, Ceylon during November
1867. These sister collections are the holotypes of Peziza epispartia, P.
flavotingens, and P. radiculosa. Le Gal (1953) recognized Phaedropezia
epispartia as one taxon synonymizing Peziza radiculosa with it. However,
she originally questionably synonymized Peziza flavotingens with Phae-
dropezia flavida. Later Le Gal (1959) proposed the combination Phae-
dropezia flavotingens since, in her opinion, two colored plates by Mme
M. Goossens-Fontana (Le Gal 1960) showed color differences sufficiently
different to warrant creation of the new taxon. Unfortunately, the holo-
type specimen of Peziza flavotingens is immature. This was indicated by
the original description (Berkeley 1875), in which it was stated “Fruit
scarcely mature.” Le Gal (1959) commented that one of the Goossens-
Fontana drawings agreed with Cooke’s illustration (plate 10, fig. 38) of
Peziza flavotingens in his Mycographia. This plate by Cooke shows
apothecia with yellow hymenia attached to the substrate by yellow
mycelia. The asci were drawn with four spores and show some granular
cytoplasm, possibly another indication that the specimen was immature.
One must regard the precise color of Cooke’s plates as questionable since
he was drawing not from living specimens, but from dried material, writ-
ten descriptions, and field notes. In addition, my study of the Goossens-
Fontana specimen, identified by Le Gal as Phaedropezia flavotingens,
does not show significant microscopic differences to distinguish it from
Acervus flavidus. I take a broad view of the significance of color varia-
tions and assume the existence of natural differences between specimens
of one species depending on substrate, age, and environmental conditions.
I refer Phaedropezia flavotingens sensu Le Gal to Acervus flavidus.

Interestingly, Peziza microspora, another synonym of Acervus epi-
spartius, has been reported from North America on two occasions. The
type collection itself was from South Carolina, and a second collection
was from Pennsylvania (in Ny). The Pennsylvania specimen was listed
by Seaver (1928) as Humaria microspora and was treated as a doubtful
member of the genus Humaria. The packet shows that it was determined
by Phillips. The type collection of Acervus aurantiacus from Michigan
represents the most northerly station yet reported for this species. Thus,
though Acervus is primarily tropical it may also occasionally be found
in the temperate areas of North America. I am not aware of any report
of this species from temperate Europe or Asia. This species was reported
from India (Uppal et al. 1935) under the name Peziza epispartia. The
specimen on which this record is based was not examined in the present
study.

SPECIMENS EXAMINED. Argentina: suelo bajo Eucaliptus, Buenos Aires, Parque
Pereyra, Iraola. 20 abril 1970, P. Merlo (ips). Ceylon: holotype of Peziza radiculosa,
Peradeniya, Nov. 1867 (x); holotype of Peziza epispartium, Peradeniya, Nov. 1867,
(x); holotype of Peziza flavotingens, Peradeniya, Nov. 1867 (xk). Congo: Panzi,

THE GENUS ACERVUS (ASCOMYCETES, PEZIZALES ) )

Chemin herbeuse 650 m. dec. 1949, Mme M. Goossens-Fontana (5105) (sr): sol,
Panzi-Kivu alt. 1650 m, nov. 1955, Mme M. Goossens-Fontana (5526) (Br); arbre
mort, Panzi-Kivu alt. 1650 m, mai 1953, Mme Goossens-Fontana (5285) (BR); bois
mort, Panzi-Kivu, mai 1952, Mme Goossens-Fontana (5248) (pr); groupés sur tronc
mort dans champs. de cultures indigens, Binga, 5 junio 1928. Mlle Goossens (765)
(pr). Madagascar: Terrestre, Institut Pasteur, 11(2) fev. 44, M. Bourguet (pc).
Malaya: on bare earth by an old termite nest in forest, Pahang, Tembeling, 10 Nov.
1930, E. J. H. Corner (spr); Pahang, Tembeling, 15 Nov. 1930, E. J. H. Corner (1269)
(Bp1); Pahang, Tembeling, 8 Nov. 1930, E. J. H. Corner (24166) (pr). U.S.A.: part of
holotype of Acervus aurantiacus on soil around roots of an elm tree in a bog, South
Lyons, Michigan, 6 October 1936, Alexander H. Smith (5044) (micH); on loose
decaying rubbish, Fairmont Park, Philadelphia, Pa., Sept. 1882, W. C. Stevenson, Jr.
(477) (Ny); holotype of Peziza microspora on damp, rotten wood near the ground,
South Carolina (kK). Vietnam: sur la terre, dans les plantations de café, Chi-Né, Tonkin,
avril 1911, Mr. Duport (531) (FH-Herb. Patouillard ).

2. Acervus flavidus ( Berk. & Curt. in Berk.) Pfister, comb. nov.

= Psilopezia flavida Berk. & Curt. in Berk., Grevillea 4:1, 1875.
= Phaedropezia flavida ( Berk. & Curt. in Berk.) Le Gal, Prodr. Flore Madagascar
4:185. 1953.

A description of this species was given by Le Gal (1953). The original
placement in Psilopezia by Berkeley and Curtis (Berkeley 1875) prob-
ably was based on the more or less broad attachment of the apothecia to
the substrate. As previously pointed out (Pfister 1973) this species is not a
Psilopezia.

Massee (1896) said “I should place the present species in the genus
Mollisia.” Such placement is untenable and apparently was based on
Massee’s belief that the asci were inoperculate.

I have collected this species on several occasions in the West Indies
and have reported a collection of it from Dominica under the name
Phaedropezia flavotingens (Pfister 1972). The ascospores were found to
be uninucleate.

Fresh apothecia of this species, when placed in FAA, release bright
yellow pigments. These pigments may also leach from dried apothecia
when rehydrated in water. References to similar soluble pigments were
made by Kanouse (1937), Korf (1963) and Gamundi (1970) in their
descriptions of Acervus aurantiacus.

In fresh material the substrate surrounding the apothecia is bound
loosely together with yellow mycelium to form a common mass. A mass
similar to this may have been the structure which was described by
Kanouse (1938) as the sclerotiform base of Acervus aurantiacus. In her
description, however, she stated, “arising from a black, tough, rubbery
sclerotiform base composed of thin-walled mycelium intermingled with
débris.” Korf (1963) could find no evidence of this structure and I have
found that the mycelial-substrate mass does not withstand drying.

SPECIMENS EXAMINED. Congo: sur detritus de palmiers, Binga, oct. 1944, Mme
Goossens-Fontana (3042) (Br). Guadeloupe: on debris, Les Mamelles, Parc Tropicale,

6 DONALD H. PFISTER

5 Jan. 1974, D. H. Pfister (806), M. Sherwood, S$. Carpenter (FH); on debris under
leaf litter, Les Mamelles, Parc Tropicale, 19 July 1973, D. H. Pfister (536), W. Sar-
riera. M. Halmos (FH). Madagascar: sur humus, Ankarafautsika, 1 jan. 1938,
R. Decary (rc), Peru: on dead sticks, leaves, etc. on the ground in the forest, Iquitos,
10 April 1948, E. J. H. Corner (1202) (spr). Puerto Rico: on soil and debris on bank,
Mayagtiez Zoo, Mayagiiez, 27 Aug. 1972, D. H. Pfister (419) and C. Pfister (FH).
U.S.A.: holotype of Psilopezia flavida Alabama, Peters (x). Venezuela: on unidentified
plant debris, mountains above El Rosario, Edo. Miranda, 1 July 1971, k. P. Dumont
(VE-1067 ), J. H. Haines, C. Blanco (xy).

UNSTUDIED SPECIES

Phaedropezia genuina Le Gal, Prodr. Flore Mycol. Madagascar 4:190. 1953.

The holotype of this species is, according to Le Gal (1953), a single
poorly preserved specimen. Since I have not seen this specimen and have
no firsthand knowledge of it, no new combination is proposed, Le Gal
(1953) maintained that smaller size of the apothecia, yellower color, and
spore size of 8.5-12 4-5 pm sufficiently distinguished P. genuina from
the other species. The spore size approaches that of Acervus flavidus.
The report by Cash (1956) of this species from Chile is based, according
to my study of her specimen, on an inoperculate Discomycete, probably
referrable to the genus Hymenoscyphus. Its asci have a definite J +- apical
pore.

P gate"
2, THE APOTHECIAL ONTONGENY OF ACERVUS FLAVIDUS
WITH COMMENTS ON A. EPISPARTIUS

SUMMARY

The ascocarps of Acervus flavidus are demonstrated to be cleistohymenial. They
open during the prohymenial phase by the formation of a distal flap which turns back
to expose the hymenium. No gametangia were seen. A similar type of development has
been observed in Acervus epispartius. It is suggested that this ontogenetic feature is a
useful generic character in Acervus and that with future studies the proper super-
generic relationship of Acervus might be discovered.

INTRODUCTION

Few members of the Pezizales have been rigorously analyzed in regard
to the ontogeny of their apothecia. The Ascobolaceae and certain other
coprophilous Discomycetes are exceptions (van Brummelen 1967, 1972,
Kimbrough 1972, Kish 1974, Jain and Morgan-Jones 1973). Such studies
potentially may elucidate relationships among species within genera and
among genera. Van Brummelen (1967) has successfully applied ontogenetic
information to his sectional classification of the genera Ascobolus and
Saccobolus. In so doing he developed a set of terminologies, employed
here, which are outgrowths and refinements of the work of Corner (1929
a,b; 1930 a,b,c). Van Brummelen’s system involves the recognition of

THE GENUS ACERVUS ( ASCOMYCETES, PEZIZALES ) fi

two features: (1) the presence or absence of a layer covering the
apothecial initials; and (2) if covered, the stage at which the hymenium
is exposed. The burden imposed by such a set of characters is great, since
apothecial primordia must be seen, as well as juvenile and mature
apothecia.

The subject of this study, Acervus flavidus (Berk. & Curt. in Berk.)
Pfist., has never been discussed ontogenetically. Material of A. flavidus
was collected in the field where initial observations were made. Since
spore germination was never obtained, the fungus has not been cultivated.

MATERIALS AND METHODS

The ascocarps and primordia used in this study were collected in
Guadeloupe, F.W.I. Voucher specimens, DHP 538, 806, and 611 are
deposited in the general mycological collection of the Farlow Herbarium
(rH). Material was killed and fixed in FAA (Sass 1958) in the field.

Pencil drawings were made by Cathleen Kk. Pfister from killed and
fixed material. This material was then infiltrated with paraffin using the
tertiary butyl alcohol method (Jensen 1962). Serial sections were made at
approximately 10 um.

Sections were processed as follows: paraffin was removed in xylene,
transferred to absolute ethyl alcohol, stained from 15-30 minutes in a
0.5% solution of Congo Red (C.I. No. 22120) in commercial ammonia,
counter stained with a saturated solution of orange G (C.I. No. 16230) in
clove oil, and returned to xylene. Wall material was stained bright,
clear red while cytoplasm was stained orange.

RESULTS

Ontogenetically the ascocarp of Acervus flavidus is cleistohymenial,
opening at the prohymenial stage. The critical developmental stages are
shown in figure 1 (A-C). In the earliest stage observed, the archihymenial
stage, the primordium was a stout, subcylindrical mass of mycelium
attached to the substrate by yellow my celium. Examination of ascocarp
sections, 8-12 »m thick, at this stage showed no differentiated gametangia.
It was composed of undifferentiated, interwoven hyphae which were 7-10
um in diameter. Toward the base of the young ascocarp the hyphae were
more loosely arranged than they were distally. The hyphae tended to
become parallel in orientation to one another in the distal portion. Some-
times the hyphae anastomose.

The opening of the ascocarp takes place during the prohymenial phase
when a fissure develops which cuts out a more or less circular flap at the
distal portion of the ascocarp (fig. 1A). This phenomenon has been
observed on several occasions in field collections and was noted in the
field by Corner (notes with specimens in srr) for A. epispartius. It thus

8 DONALD H. PFISTER

Fic. 1 (A-C). Developmental phases of Acervus flavidus (approx. 5x). A. Two juvenile ascocarps.
The ascocarp on the right shows the late archymenial phase or early prohymenial phase. The asco-
carp on the left shows the prohymenial phase after rupture of the distal portion to form a semi-
circular flap (drawn from DHP 611). B. Ascocarp at mesohymenial phase (drawn from DHP 806).
C. Ascocarps at telohymenial phase situated on a mycelial mat (drawn from DHP 806).

seems to occur commonly and regularly. The flap remains attached to one
side of the disc where it can be seen through most of the successive
developmental stages (fig. 1B). The flap is composed of hyphae which, in
section, appear to form a pseudoparenchyma of small diameter cells. At
the time of rupture short paraphyses are present which form a discrete
hymenium. The ascocarp at this stage is composed of large diameter
cylindrical cells or wide hyphae interspersed with thinner hyphae.

Distal rupture and separation of the flap from surrounding tissue
resulted from an increase in marginal growth. In section the margins of
ascocarps at prohymenial and mesohymenial phases were composed of
loosely interwoven flexuous hyphae. This is the region of active growth
and from this zone arise all successive paraphyses and the excipular
tissue.

Ultimately the apothecium reaches a diameter of up to 1.5 cm and is

THE GENUS ACERVUS ( ASCOMYCETES, PEZIZALES ) 9

either slightly concave, flat, or convex. At times it appears to be subses-
sile; a short thick base develops through the aggregation of mycelium
and debris from the substrate. On ele a mass one or more apothecia
may be situated as in figure 1C. By the telohymenial phase the flap
generally has been lost.

DISCUSSION

The development of Acervus flavidus as outlined here is unique. Other
members of the Pezizales have been shown to be cleistohymenial and to
open during the prohymenial phase but none have been described as
having the discrete flap of tissue which is characteristic of Acervus. The
mechanism is particularly effective since the flap does not interfere with
spore discharge, yet the hymenium is covered during a critical early
stage of development when the apothecium is likely to dry out. Spores
are forcibly discharged. Although I have not observed it, Corner noted
puffing in one of his Malaysian collections according to field notes ac-
companying specimens in BPI.

Following van Brummelen’s (1967) successful use of ontogenetic
features in the sectional taxonomy of the Ascobolaceae, such characters
have been used increasingly as taxonomic criteria. The coprophilous
Discomycetes in particular have been well studied. However, few studies
have been done on terrestrial members. This is the case partly because
ontogenetic studies are not always possible since, for the majority of the
Pezizales, adequate material can only be collected in nature and cannot
be produced in culture. Still, ontogenetic information is a valuable
classificatory tool and as van Brummelen (1973) suggested, it may be
particularly significant at the supraspecific level.

In Acervus I believe the ontogeny is essentially identical in both rec-
ognized species and I consider this dev elopmental character to be useful
at the generic level. As previously stated, the taxonomic position of
Acervus is in doubt. I retain it as did Korf (1972, 1973) in Sowerbyelleae,
the position assigned Phaedropezia by Le Gal (1969). Until ontogenetic
information for the other genera of the tribe can be obtained, the signif-
icance of this unique mode of development in Acervus cannot be eval-
uated above the generic level. Nonetheless, ontogenetic information may
prove to be of use in determining the legitimacy of the tribe.

ACKNOWLEDGMENTS
I wish to thank the Curators and Directors of the following herbaria for the loan of
specimens: Instituto de Botanica C., Spegazzini, Buenos Aires (Lps); Muséum National
Histoire Naturelle, Laboratoire de Cryptogamie, Paris (pc); Cornell Plant Pathology
Herbarium, Ithaca (cup); the Herbarium and Library, Royal Botanical Gardens, Kew
(Kk); Jardin Botanique de I’Etat, Bruxelles (Br); University Herbarium, University of
Michigan, Ann Arbor (MicH); ie New York Botanical Garden, (Ny).

10 DONALD H. PFISTER

LITERATURE CITED

Arpin, N. 1969. Les carténoides des Discomycétes: Essai chimiotaxinomique. Bull.
Soc. Linn. Lyon Suppl. 38:3-169.

BerkeLry, M. J. 1875. Notices of North American fungi. Grevillea 4:1-16.

BRUMMELEN, J. VAN. 1967. A world monograph of the genera Ascobolus and Sacco-
bolus (Ascomycetes. Pezizales ). Persoonia (Suppl.) 1:1-260.

a . 1972. Ascocarp ontogeny and a natural classification of the Ascobolaceae.
Persoonia 6:389-394,

Casn, E. K. 1956. Some Chilean Discomycetes collected by Roland Thaxter. Sydowia
Beiheft 1;289-293.

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THE GENUS ACERVUS ( ASCOMYCETES, PEZIZALES ) 11

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