The North American Slime-Moulds Part 39

1911. _Stemonitis fusca var. trechispora_ Torr., List., _Mycetozoa, 2nd ed._, p. 144.

Fructification in form of aggregations of more or less coalescent, small, dark-brown or dull black, sessile sporangia; hypothallus continuous, well-developed; columella black, gently tapering to a point beneath the apex, the capillitial branches, irregular, few, but pa.s.sing into an open rather evenly-meshed net, the mesh several times the spore-diameter, free-ending branch-tips not lacking; the spores by transmitted light distinctly brown, the epispore a beautiful reticulation, a dozen or more cells to the hemisphere, 10-12 .

This is entered sometimes as a variety of _S. fusca_ to which species relations.h.i.+p would seem remote. The differences lie in form, color and structure. The spores alone are distinctive; there are none such, so far, none just like them, elsewhere in the genus. Torrend and Lister both enter the form as varietal; why not set it out, and save questions?

The habitat approaches that of _Amaurochaete_, but the sporangia are distinct.

For our specimens we are indebted to the kindness of Dr. Roland Thaxter.

The specimens were taken in a half-dry marsh, near Cambridge.

Material from Toronto sent by Professor Faull is also provisionally here referred. The form has netted spores, but they are not quite the same.

The structure besides is more that of an amaurochaete; it has the peculiar basal webs and band-like stipes at base, stipes that never rise from horizontal to perpendicular and characterize _Reticularia_ and especially _Brefeldia_ as well as the usual amaurochaete. See Plate XX., Figs. 9, 9_a_, 9_b_.

3. STEMONITIS FUSCA (_Roth_) _Rost._

PLATE VI., Figs. 4, 4 _a_, 4 _b_

1787. _Stemonitis fusca_ Roth, _Rom. Mag. Bot._, I., p. 26.

1875. _Stemonitis fusca_ (Roth) Rost., _Mon._, p. 193.

1892. _Stemonitis fusca_ Rost., Ma.s.see, _Mon._, p. 72.

1895. _Stemonitis fusca_ Roth, List., _Mycetozoa_, p. 110.

1899. _Stemonitis fusca_ (Roth) Rost., Macbr., _N. A. S._, p. 115.

1899. _Stemonitis maxima_ Schw., Macbr., _N. A. S._, p. 116.

Sporangia tufted, generally in small cl.u.s.ters 6-8 mm., the individual sporangia slender, cylindric, blue-black or fuscous, becoming pallid as the spores are lost, stipitate; stipe short, about one-fourth the total height, black, s.h.i.+ning; hypothallus scanty, but common to all the sporangia; columella prominent, attaining almost the apex of the sporangium, freely branching to support the capillitial net; capillitium of slender dusky threads, which freely anastomose to form a dense interior network, and outwardly at length combine to form a close-meshed net; spores pale, dusky violet, usually beautifully spinulose-reticulate, but sometimes warted or spinulose only, or nearly smooth, 7-7.5 .

As here set out the description is intended to include _S. maxima_ Schw.

of the former edition. Rostafinski, Mon. _l. c._, describes _S. fusca_ Roth. as having "spores smooth." Since most American gatherings have reticulated spores, and since Schweinitz described a black American species, his specific name seemed appropriate for all except smooth-spored forms.

In the meantime two things have happened; Mr. Lister has examined the specimens remaining in the Strasburg herbarium and finds them with reticulate spores. The statement quoted from the _Monograph_ evidently does not apply to _all_ of Rostafinski's material; but under the circ.u.mstances the name _fusca_ may easily take the field, especially since another discovery makes for the same conclusion. The evidence is good that _S. maxima_ Schw. was indeed the largest, i. e. perhaps, the _tallest_ stemonitis he ever saw! probably, as his scanty herbarium-remnant shows, _S. fenestrata_ Rex!

4. STEMONITIS UVIFERA _n. s._

PLATE XX., Figs. 8, 8 _a_, 8 _b_, 8 _c_.

Sporangia tufted, generally in medium-sized cl.u.s.ters much as in _S.

fusca_. The individual sporangium 7-9 mm. high, dark, slender, brown, becoming dull black or pallid as the spores are lost, stipitate, the stipe about one-fourth to one-third the total height, black polished s.h.i.+ning; hypothallus distinct, common to all sporangia, purple-brown, s.h.i.+ning; columella distinct, attaining almost the summit of the sporangium but inclined to waver a little at last, in other words, flexuose toward the top, freely branching, the branches rather stout, anastomosing to support the capillitial net; the meshes larger, several times the spore-diameter, the spores sooty-brown, distinctly warted or spinulescent, about 7-8 , cl.u.s.tered in groups of four or more.

Mt. Rainier, Was.h.i.+ngton,--1914.

5. STEMONITIS DICTYOSPORA _Rost._

1873. _Stemonitis dictyospora_ Rost., _Mon._, p. 195; _Myc. Fen._, pp. 114, 122.

1879. _Stemonitis dictyospora_ Rost., Ma.s.s., _Mon._, p. 83(?).

1888. _Stemonitis dictyospora_ Rost., _Sacc. Syl. Fung._, Vol. VII., p. 397.

1893. _Stemonitis castillensis_ Macbr., _Nat. Hist. Bull._, Vol. 11, p. 381.

PLATE X., Figs. 5, 5 _a_, 5 _b_.

Sporangia crowded in colonies of unusual size, 4-8 cm., tall, rigid 18-25 mm., slender, erect, stipitate, black throughout; the columella prominent, reaching nearly to the apex, abundantly branched, the branches forming an intricate dark brown capillitium; the net large-meshed several times the spore-diameter; the spores reticulate, spinulose, clear violet, 7-8 .

We here recover as is believed one of Rostafinski's best-described species. Our material is from Nicaragua, by kindness of Professor s.h.i.+mek. Its relations.h.i.+p is with _S. fusca_ where Rostafinski placed it.

The phrase describing spore-color is his.

6. STEMONITIS NIGRESCENS _Rex._

1891. _Stemonitis nigrescens_ Rex, _Proc. Phil. Acad._, p. 392.

1911. _Stemonitis fusca_ Roth, Lister, _Mycetozoa, 2nd ed._, p. 143.

Sporangia gregarious, upon a common hypothallus, erect, small, cylindric, stipitate; stipe black, extremely short, about half a millimetre; columella reaching the apex; capillitium violet-black, darker near the surface, forming a complete superficial net at the lower part of the sporangium only, elsewhere irregular or vanis.h.i.+ng; spore-ma.s.s nearly black; single spores violet-black under the lens, the epispore spinulose and reticulate, about 8 .

The author of this species remarks: "This species is noteworthy for its comparatively short stipes, its very spinulose spores, and its black or nearly black color, the slight violet tint being only apparent on close inspection, especially in fresh moist specimens."

It is a small but very beautiful form, at first sight to be mistaken for a short _S. fusca_, though much more intensely black. The capillitium is concolorous, the inner network of rather few open meshes, the outer of large hexagonal openings, the arcuate threads of which are remarkable for the size, and especially the number, of the peridial processes, as many as five or six sometimes appearing along one side of a single mesh.

The stipe is very short, and the columella runs as a straight, gradually diminis.h.i.+ng axis to the very apex of the sporangium. Total height 3-5 mm.

The English _Monograph_ includes this with _S. fusca_; but it seems quite distinct in size, habit, color, etc., and has been found in the mountainous regions of Virginia and North Carolina, as well as about Philadelphia.

7. STEMONITIS VIRGINIENSIS _Rex._

1891. _Stemonitis virginiensis_ Rex, _Proc. Phil. Acad._, p. 391.

1899. _Stemonitis virginiensis_ Rex, Macbr., _N. A. S._, p. 130.

1911. _Comatricha typhoides_ Rost., List., _Mycetozoa, 2nd ed._, p. 158.

Sporangia erect, gregarious, from a common hypothallus, generally cl.u.s.tered, cylindric or elongate-ovate, stipitate; stipe black, s.h.i.+ning; columella reaching the apex, where it blends with the capillitium; capillitium delicate, the meshes of the net small, scarcely greater than the diameter of the spores; spore-ma.s.s umber brown; epispores reticulated, with ten or twelve meshes to the hemisphere, 5-7 .

This is a beautiful, and, as it seems to us, a very distinct, species.

The markings on the epispore are sufficient to identify it. These are conspicuously banded somewhat as the spores of _Trichia favoginea_, for example. In habit, size of the sporangia, and capillitial branching, this species recalls _Comatricha typhoides_ (Bull.) Rost. All the sporangia examined are, however, plainly stemonitis in type, possessing the characteristic superficial net.

Until further light this may stand as offered in the first edition. Miss Lister prefers to enter it, banded spores and all, with the comatrichas, on account of color, size and occasional default (?) of surface net.

Virginia, _Dr. Rex._

8. STEMONITIS WEBBERI _Rex._

PLATE XI., Figs. 6, 7, 8.

1891. _Stemonitis webberi_ Rex, _Proc. Phil. Acad._, p. 390.

Sporangia cl.u.s.tered, usually in small tufts 1 cm. wide, rusty brown in color, 8-10 mm., including the stipe, which is jet black, s.h.i.+ning, and much expanded at the base; hypothallus continuous, well-developed, a thin, transparent pellicle; columella black, tapering upward, giving off at intervals the capillitial branches, and becoming dissipated just below the obtuse apex; inner capillitial network very open, the branches far apart, anastomosing but a few times before breaking into the surface net to form large, irregular meshes, 50-125 ; spores minutely roughened, fuscous, 8-9 .

These three forms, 8, 9, 10, are sometimes entered as varieties of a single species. Dr. Rex himself was inclined to take that view. There is no doubt of close similarity; it is a question of clearness in our dealing with the subject.

All three forms occur abundantly in the Mississippi Valley, but are generally,--always, as it seems to the writer,--distinguishable by the hand-lens. If we take No. 9 as type, 10 has an eccentric columella; 8 is shorter, about 1 cm., of a different tint, Dr. Rex even says "spores ferruginous in ma.s.s". To the west and southwest, the capillitium becomes coa.r.s.er, more decidedly brown. In short, however similar in presentation the phases may sometimes appear, it would seem that each at its best is distinct enough for immediate recognition.