The Myxomycetes of the Miami Valley, Ohio Part 2

Growing on old wood. Sporangium .30-.35 X .25-.30 mm, the stipe two to four times as long as the sporangium. A minute species, easily recognized by its almost uniform color of bright new copper.

IV. DICTYDIUM, Schrad. Sporangium simple, depressed-globose, stipitate, cernuous; the wall regularly thickened on the inner surface by numerous convergent ribs, which extend from base to apex and are united by fine transverse fibers, thus forming a network of rectangular meshes; the basal portion of the membrane sometimes persists as a calyculus, the upper part disappears at maturity. Spores globose; purplish.

The ribs run from base to apex like the meridians on a globe; they are simple, or here and there they separate into two divergent branches, which sometimes again converge into one; at the apex of the sporangium there is usually a small irregular net in which all the ribs terminate.

1. DICTYDIUM CERNUUM, Pers. Sporangium depressed-globose, umbilicate at the apex, stipitate, cernuous, purplish-brown in color; the calyculus granulose within, occupying from one-fourth to one-third of the sporangium, the ribs united by firm, persistent fibers. Stipe not very long, erect, tapering upward, bent at the apex, purplish-brown, the apex pale and pellucid, standing on a small hypothallus. Spores purplish-brown in ma.s.s, globose, even, 5-7 mic. in diameter.

Growing on old wood. Sporangium .4-.5 mm. in diameter, the stipe two or three times longer than the diameter of the sporangium. This appears to be the species figured and described by Rostafinski and by Ma.s.see.

2. DICTYDIUM LONGIPES, Morg. n. sp. Sporangium large, depressed-globose, the apex umbilicate, stipitate, cernuous, dark purple in color; calyculus usually wholly wanting, the ribs united by weak fibers, which are easily torn asunder, allowing the ribs to curl up inwards. Stipe very long, flexuous, tapering upward, curved and twisted at the apex, dark purple in color, standing on a thin hypothallus. Spores in the ma.s.s dark purple, globose, even, 5-7 mic. in diameter. See Plate III, Fig.

12.

Growing on rotten wood, mosses, etc. Sporangium .5-.7 mm. in diameter, the stipe three to five times as long. This is a much larger species than the preceding; it has a uniform dark purple hue, the stipe is very long and much bent and twisted, the ribs of the sporangium are soon torn apart and rolled inward.

EXPLANATION OF PLATE III

Fig. 1.--Licea biforis, Morgan, n. sp.

Figs. 2, 3, 4.--Diagrammatic representation of the structure of Tubulina

Fig. 5.--Lycogala conic.u.m, Pers., natural size

Fig. 6.--Lycogala exiguum, Morgan, n. sp., natural size

Fig. 7.--Lycogala epidendrum, Buxb., natural size

Fig. 8.--Lycogala flavofusc.u.m, Ehr., natural size

Fig. 9.--Portion of tubule of Lycogala flavofusc.u.m

Fig. 10.--Reticularia splendens, Morgan, n. sp., natural size

Fig. 11.--Cribraria cuprea, Morgan, n. sp.

Fig. 12.--Dictydium longipes, Morgan, n. sp.

[Ill.u.s.tration: The Journal of the Cin. Soc. Natural History.

VOL. XV. PLATE III.]

From the Journal of the Cincinnati Society of Natural History, April, 1893.

THE MYXOMYCETES OF THE MIAMI VALLEY, OHIO.

BY A. P. MORGAN.

Second Paper.

(Read May 2, 1893.)

ORDER III. PERICHaeNACEae.

Sporangia sessile or plasmodiocarp; the wall a thin membrane, with a more or less thickened outer layer of minute brownish scales and granules. Capillitium of long and very slender tubules, proceeding from numerous points of the sporangial wall, loosely branched, forming no evident network, the surface minutely warted or spinulose. Spores globose, oval, or somewhat irregular, yellow.

The order is distinguished by the sessile sporangia, with thick brown walls, and the very slender threads of the capillitium, with irregular and indefinite markings.

TABLE OF GENERA OF PERICHaeNACEae.

1. PERICHaeNA. Sporangia more or less depressed, roundish or more commonly polygonal and irregular, dehiscent in a circ.u.mscissile manner.

2. OPHIOTHECA. Plasmodiocarp terete and more or less elongated, bent and flexuous, sometimes annular or reticulate, irregularly dehiscent.

I. PERICHaeNA, Fr. Sporangia more or less depressed, roundish or more commonly polygonal and irregular, the edges approximate and sometimes confluent; the wall a thin membrane, with a thick dense yellow-brown outer layer of minute scales and granules, becoming darker at the surface, dehiscent in a circ.u.mscissile manner. Capillitium of very slender loosely-branched threads, with the surface minutely warted.

Spores globose, oval or somewhat irregular, yellow.

Distinguished from Ophiotheca by the flattened sporangium with a regular circ.u.mscissile dehiscence.

1. PERICHaeNA DEPRESSA, Lib. Sporangia very much depressed, polygonal, irregular, crowded, the edges contiguous, sometimes confluent; the wall thick, yellow-brown within and scarcely impressed by the spores; the outer surface smooth, brown-red to brown or blackish in color, dehiscent in a circ.u.mscissile manner. Capillitium of slender loosely-branched threads, 1-3 mic. in thickness, the surface merely uneven or very minutely warted. Spores globose, yellow, 9-10 mic. in diameter. See Plate I, Fig. 13.

Growing on the inside of the bark of Juglans, Acer, etc. Sporangia variable in size, 7-1.3 mm. in breadth, irregular and angular, much flattened. It is said to include _Perichaena vaporaria_, Schw.

2. PERICHaeNA IRREGULARIS, B. & C. Sporangia depressed, irregular, polygonal, crowded, the edges contiguous and sometimes confluent; the wall thick, yellow inside and faintly reticulately impressed by the spores, the outer surface smooth, purplish-brown, dehiscent in a circ.u.mscissile manner. Capillitium of slender-loosely branched threads, about 2 mic. in thickness, the surface minutely warted or spinulose.

Spores subglobose, yellow, 9-10 mic. in diameter.

Growing on the outer bark of Acer, etc. Sporangium .5-.6 mm. in width, closely crowded and irregular. It is much smaller than _Perichaena depressa_, and its threads are more distinctly warted and spinulose.

3. PERICHaeNA CORTICALIS, Batsch. Sporangia globose, the base depressed, gregarious: the wall thick, yellow within and distinctly reticulately impressed by the spores, the outer surface reddish-brown or yellow-brown in color, dehiscent in a circ.u.mscissile manner. Capillitium of slender loosely-branched threads, about 2 mic. in thickness, the surface very minutely warted. Spores subglobose, yellow, 10-12 mic. in diameter.

Growing on the inside of the bark of Elm. Sporangia .5-.6 mm. in diameter, quite regular in shape, with a slightly flattened base. My specimens are from Prof. McBride, of Iowa.

4. PERICHaeNA MARGINATA, Schw. Sporangia depressed, polygonal, approximate and sometimes confluent, the surface cinereous-pulverulent, seated on a silvery hypothallus; the wall firm, thick, the outer surface yellow-brown, covered with minute whitish scales, the inner surface yellow, deeply reticulately impressed by the spores which rest against it, dehiscent in a circ.u.mscissile manner. Capillitium consisting of a few simple or somewhat branched threads or well-nigh obsolete. Spores subglobose, yellow, 12-14 mic. in diameter.

Growing on the outer surface of the bark of Acer, f.a.gus, etc. Sporangia .4-.6 mm. in width. This is plainly _Perichaena cano-flavescens_, Raunkier. I do not find any threads of a capillitium in my specimens.

II. OPHIOTHECA, Currey. Plasmodiocarp terete and more or less elongated, bent and flexuous, sometimes annular or reticulate, the surface not polished or shining: the wall a thin membrane, with a thin outer layer of minute scales and granules, irregularly dehiscent. Capillitium of very slender loosely-branched threads, with the surface minutely warted and spinulose. Spores globose, oval or somewhat irregular, yellow.

Distinguished from Perichaena by the terete plasmodiocarp and by the more spinulose capillitium. _Cornuvia_ of Rostafinski.