PART 1

Pyrenocollema tichothecioides (Arn.) R. C. Harris s. lat.
Since my thesis I have examined the type material of this species, the type of Xanthopyrenia Bachm.,
and it is clearly congeneric with Pyrenocollema. This is where most of the obvious problems occur. Michigan
material cited in my thesis has an ascospore size nearer that of P. strontianense (Swinscow) R. C. Harris but
are on calcareous rock. Material reported from Louisiana on sandstone is not available but more recent
collections seem to be better placed in or near Lichenothelia D. Hawksw. A recent collection on sandstone
from Mississippi is closer to P. strontianense but apparently differs in asomatal characters. Specimens from
the West seem to be closer to P. tichothecioides. Until a large amount of material is amassed and studied at
one time, these problems cannot be resolved.
Pyrenocollema zonatum (Müll. Arg.) R. C. Harris, comb. nov.
Arthopyrenia zonata Müll. Arg., Flora 71: 549. 1888. Type. BRAZIL. "Saxicola ad flumen Iguape
prope Iporanga in Brasilia meridionali", Puiggari 3025, 3027 (G, syntypes; BM, M, isosyntypes).
ZWACKHIOMYCES Grube & Hafellner
The species described here as Z. arenicola has the ascomatal pigmentation, physis type, ascospore
type and lifestyle of Zwackhiomyces. Not having seen verified material of a real Zwackhiomyces, I am not
sure about the ascus type. The apex is not in agreement with Grube's illustrations and the ascus is broadest
at or below the middle. Also the ascospores have a diffuse gel sheath. I would not like to think another genus
is needed but the possibility exists.
1. Ascospores 28-37 × 10-13 µm; on unidentifiable areolate thallus or without
obvious host; southern Georgia ......................................................................... [Z. arenicola R. C. Harris]
1. Ascospores 24-27 × 7.5-8.5 µm; without obvious host but green algae present;
Louisiana ..............................................................................................[Zwackhiomyces sp. Harris 11406]
Zwackhiomyces arenicola R. C. Harris, sp. nov.
NOTES
Ascomatis in areolis lichenis ignoti vel super saxum arenaceum nudum et ascosporis 29-37 × 9-13 µm.
Type. GEORGIA. Johnson County: 2 mi N of Adrian on Georgia Highway 15, 32°34'N, 82°35'W, ca. 80 m, small
Altamaha Grit sandstone outcrop on slope, 18 Mar 1995, Harris 36282 (NY, holotype)
Ascomata initially immersed in and then erupting through small, white, unidentifiable areoles on moist
sandstone or growing sessile and naked directly on moist sandstone with a layer of green algae, subglobose,
ca. 0.2-0.35 mm diam.; when growing immersed, ascomata often surrounded by a layer of paler brown
hyphae, when growing exposed, ascomata black and glossy; ascomatal wall pale below when immersed,
entirely dark when exposed. Asci elliptical to pyriform, ca. 110-135 × 30-45 µm, with eight irregularly arranged
spores. Ascospores 28-37 × 10-13 µm, 2-celled, becoming 4-celled when overmature, ovoid, constricted at
septum, becoming brownish and granular ornamented with age, with a watery gel sheath; upper cell slightly
shorter and broader than the lower; pycnidia not found.
All the known collections are from Altamaha Grit which is proving to be a habitat for many interesting
lichens. The species is so inconspicuous that its absence from similar outcrops elsewhere in the South may
be a collection (or lack of) phenomenon. A very similar species differing only in smaller ascospores occurs on
sandstone in Louisiana. Assuming Z. arenicola is correctly assigned to genus, it is distinctive in the larger
ascospores. Other species of Zwackhiomyces are reported by Grube (Nova Hedwigia 51: 283-360. 1990)
from Clauzadea, Lecanora, Mycobilimbia and Porpidia. I am unable to determine the host for Z. arenicola,
partly I believe, since the habitat is sufficiently wet that the lichen does not form a typical thallus.
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