The North American Slime-Moulds / A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America, with Notes on Some Extra-Limital Species

by Thomas H. Macbride

Key to the Species of Cribraria

A. Sporangia with spores ochraceous or brownish.
	a. Sporangia larger, .5 mm. or more.
		1. Net poorly developed, sometimes merely indicated		1. C. argillacea
		2. Net conspicuous, nodes expanded, not swollen.
			i. Calyculus reticulately thickened, ill-defined above	2. C. macrocarpa
			ii. Calyculus with radiant lines or ribs; net small-meshed; free ends none	6. C. aurantiaca
			iii. Net wide-meshed, calyx rufous	4. C. rufa
			iv. Calyx replaced by ribs	5. C. splendens
		3. Net conspicuous, nodules swollen.
			i. Net-threads simple; free ends many	7. C. dictydioides
			ii. Net-threads often parallel in twos or threes	8. C. intricata
	b. Sporangia small, less than .5 mm.
		1. Nodes not expanded		3. C. minutissima
		2. Nodes well shown.
			i. Calyculus distinctly marked by radiant lines, nodes round	10. C. tenella
			ii. Calyculus minute or none; nodes prominent	11. C. microcarpa
B. Sporangia more or less marked with purple or violet tints.
	a. Purple or violet throughout.
		1. Net poorly developed		12. C. violacea
		2. Net well developed.
			i. Meshes regular and the nodes distinct	14. C. elegans
			ii. Meshes and nodules irregular	13. C. purpurea
	b. Purple tints confined chiefly to plasmodic granules on the calyculus and stipe.
		Net with nodes well expanded.
			i. Stipe short, not more than double the sporangium; net and calyculus both well developed	9. C. piriformis
			ii. Stipe many times the sporangium, weak	15. C. languescens
			iii. Stipe slender, sporangium copper-colored	16. C. cuprea

1. Cribraria argillacea Pers.

[Plate XII]., Figs. 12, 13; [Plate XVII]., Fig. 1.

• 1791. Stemonitis argillacea (Pers.) Gmel., Syst. Nat., II., 1469.
• 1796. Cribraria argillacea Pers., Obs. Myc., I., p. 90.

Sporangia dull ochraceous-olivaceous, globose, nearly 1 mm. in diameter, sessile or short stipitate, closely gregarious or crowded, the peridial walls at maturity smooth, shining, except above, long persistent, obscurely reticulate, with irregular thickenings which at the apex at length present the appearance of an irregular, coarsely meshed net without nodal thickenings; stipe very short, stout, erect, reddish brown, spore-mass ochraceous, spores by transmitted light pale, spinulose, 5–6 µ.

This species stands just on the border-line between the tubiferas and the genus now before us. While on the one hand it possesses many characters such as the habit, form of sporangium, which are distinctly tubuline, on the other it shows in the upper peridial wall definite reticulations which suggest Cribraria. In freshly formed sporangia the reticulations are barely visible in the crown; later on they are more manifest, until, as spore-dispersal proceeds; the cribraria characters come out with sufficient distinctness, and in empty sporangia the reticulations may be seen to affect the entire peridial wall. The nodes are not expanded. The spores are pale by transmitted light, spinulose, about 6 µ. Plasmodium lead-colored. Found sometimes in large patches on rotten logs of various species. Not uncommon. Cf. Lindbladia effusa.

New England, New York, Pennsylvania, South Carolina, Ohio, Illinois, Iowa, Washington; Canada.

2. Cribraria macrocarpa Schrader.

[Plate XVII]., Fig. 2.