LICHENS AND LICHEN. PARASITES

DODGE-LICI-IENS AND LICHEN PARASITES
LEI~~COLLEMA Vainio
I;c.pl~ocolle~~lci Vail~io, Ett~dc Lich. BrCsil, 1, 232 ; 1890.
Type : 1,. cirriericc~n~irrz Vainio.
Tl~allns crustose, homoeomeroas, ecorticate, of colonics of Nostoc, separated by a fcm thin-
\\illled I~yphcle. Apothecia sessile, biatoriilc or sublccideinc ; pal.atheeium pseudopalpicl~ymatous ;
ilhc.osl,ores cllipsoiclal, unicellular, hyalinc.
This genus has prc\~iouslp been known only froin Brazil and Nva Caledouia, bttt it is so
~~1.y iilcollspiciloils that it may have been overlooked i11 other localities. The systematic relation-
:liil, is problematical. It \\.as placed in thc Collemaceae by its author and by Zahlbruckner,
\\.llilc lieinke, Jahrh. Wiss. Bot., 28, 236-238; 1895 and A. L. Smith who added a new species
(Jour. Linn. Soc. Bot., 46, 78; 1926) have placed it in the Pannariaceae. Our species certainly
lliis the pcculiar spores of the Pannariaceae, although it must be admitted that the thallus is a
~ery priinitive structure, consisting of almost discrete colonies of Nostoc with a thick, brownish
slleath, with so few cells that the colonies might almost be mistaken for Xanthocapsa.
A. H. Magnussoii, Hedwigia 78, 219-221 ; 1938, describes L. europueztnt, adding notes on the
type of L. an~ericanum Vaino and calls attention to a group of species in Par~nteliella centring
about P. deficiens (Nyl.) Zahlbr. which have a similarly reduced thallns. He reinailis non-cominitttll
as to the systematic position of the genus.
LEPROCOLLEMA OBSCURIUS (Nyl.) Dodge, comb. 1101~.
Parntcrria obscltrior Nyl. i11 Crombie, Jour. not. Brit. For., 13, 334; 1875. Jour. Linn. Soc. Bot.,
15, 183; 1876. Phil. Trans. Roy. Soc. [London], 168, 48; 1879. Hept. Sci. Results Voy.
"Challenger" Bot. 1, 2, 234 ; 1885.
Type: Kerguelen, Observatory Ray, A. E. Eaton (Venus Transit Exp.) on ground among
decayed mosses associated with Psoroma hirs~tulum~, not seen.
Thallus crustose, very dark green to black, covering small areas of the sides of a pebble
coated with a film of mud, snbareolate, areoles about 0.1 mm. in diameter; ecorticate, homoeomerous
; algae of discrete or ?ornewhat concrescent colonies of Nostoc, sheath relatively thin and
not very distinct in the interior of the thallus, forming more or less spherical colonies about 30p
in diameter, with a thick yellow brown sheath at the surface, where they have not yet been
illvaded by the hyphae. [These free-living colonies are interiningled with short filaments of
Scytonema and perhaps other genera of Myxophyceae]. Hypothallus not seen.
Apothecia black, sessile, 0.1-0.4 mm. in diameter, disc urceolate at first, becoming plane;
parathecium about 120p thick at the side of the thecium, carbonaceous above: extending under
the hypothecium as a layer of small-celled pseudoparenchyma, about 75p thick, enclosing small
rock crystals and making sections difficult to cut; hypothecium about 50p thick in the ckntre,
thinning toward the margin, of slender, conglutinate, deeply staining, septate hyphae, more or
less subvertical in the centre, becoming increasingly periclinal toward the margin; thecium
130-140p tall; paraphyses slender, sparingly septate; tips not thickened, relatively few in the
thecia1 gel ; asci about 85 X 15p, tips conspicuously thickened when young, 8-spored ; ascospores
monostichous below, distichous above, long ellipsoidal, ends rather acute in the ascus, becoming
relatively shorter and broader with more rounded ends when free, 15-26 X 9.8-7p, wall about
2p thick, roughened, both without and within.
As is often the case when spores show considerable variation in linear dimensions, the spore
volume is nearly a constant, as the shorter lengths are correlated with the broader diameters.