Proceedings of the American Academy of Arts and Sciences. VOL. XLVIII. No. 10.-SEPTEMBER, 1912. CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORY OF HARVARD UNIVERSITY. LXXI. - PRELIMINARY DESCRIPTIONS OF NEW SPECIES OF RICKIA AND TRENOMYCES. BY ROLAND THAXTER. CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORY OF HARVARD UNIVERSITY. LXXI. PRELIMINARY DESCRIPTIONS OF NEW SPECIES OF RICKIA AND TRENOMYCES. BY ROLAND THAXTER. Received August 19, 1912. RICKIA. THE genus Rickia has proved to be a large and varied one, and although I have enumerated below only those forms parasitic on Acari which have come under my notice, many others are known to me on a variety of hosts, an account of which I have reserved for a future paper. The general habit appears to be very variable, including in addition to the condition seen in the type form, others in which the median cell-series is undeveloped, as well as various species with a more or less complicated system of branches. The antheridial characters, moreover, appear to be equally variable. Not only do the antheridia which are extraordinarily abundant in some species seem wholly lacking in others, but their character may vary in different cases. In some there may be a single antheridium, only, similar to that of Peyritschiella, definitely placed at the base of the perithecium; or an antheridium of this type may be associated with others of the normal habit variously disposed. Again even in forms having the three characteristic cell series, antheridia may be present like those of the genus formerly separated as Distichomyces, each antheridial cell becoming more or less free in a compact group. Since both the antheridial characters and those of the receptacle thus appear to be so variable, it has not seemed desirable to limit the genus to the type form as illustrated by Rickia Wasmanni, and I have therefore given it a more liberal interpretation; including under it forms with two or with three cell-series, whether they be simple or branched, and whether their antheridia be of the Rickia or the Distichomyces type. The latter genus is, therefore, abandoned, one species only, Rickia Leptochiri, being involved in this change. The only American form, R. minuta, thus far recorded on Acari, has been described by Paoli ("Redia," Vol. VII, fasc. 2, 1911, republished in Malpighia, Vol. XXIV, 1912) from immature specimens with undeveloped perithecia, a practice which it is surely most desirable to avoid in the systematic study of a group which presents such great difficulties as do the Laboulbeniales. I have been fortunate, however, in obtaining abundant material of this species, fully matured, from the Amazon region, for which as well as for other hosts, I am indebted to the kindness of Mr. W. H. Mann who has allowed me to look over his collections made on the Leland Stanford Expedition in 1911. I am further greatly indebted to the kindness of Messrs. T. Petch, Geo. Schwab and J. B. Rorer who have most generously collected or caused to be collected for me numerous insects, in Ceylon, Kamerun and Trinidad respectively, from among which a majority of the following hosts were obtained. I am also indebted for two species of Acari collected in Grenada to Mr. C. T. Brues and kindly placed at my disposal; while lastly I am much indebted to Mr. Nathan Banks for his determinations of the host-genera. In the following diagnoses I have assumed that the side bearing the perithecium is "anterior." The spore measurements are for the most part made within the perithecium. Rickia furcata nov. sp. Furcate, sometimes irregularly branched. Basal cell short and rather stout, the receptacle above it dividing in two straight divergent branches; an anterior, bearing a perithecium, and a posterior. Anterior branch consisting of a series of usually eleven cells, the lower superposed horizontally, the upper obliquely; all cutting off appendiculate cells externally; the series extending nearly to the apex of the perithecium, to which it is united throughout its length; the second cell of the series extending inward below the base of the latter, the outline of which is symmetrically subfusiform, the inner lip-cell protruding as a finger-like process. Posterior branch indeterminate, formed by a double series of cells which are more or less regularly paired above the second cell of the outer row, the third cell bearing the primary appendage on its narrow subtending and long cylindrical basal cell; many, but not all of the cells above in both rows cutting off distally and externally small cells which bear well-developed appressed appendages or antheridia (?). Appendages subcylindrical, 8-16 X 2.5 μ. Perithecium 30-40 X 8-10 μ, including terminal projection (2.5-3 μ). Spores about 25 × 2.5 μ. Total length to tip of perithecium 40-70 μ, to tip of posterior branch 50-175 μ. On Euzercon spp. No. 2431, Trinidad; No. 2236, Manaos, Amazon; No. 2058, Grenada, W. I. This species, and to a more marked degree the following, depart greatly from the normal type, and would be placed in a new genus with little hesitation were it not for the structure which characterizes various others of the many undescribed species known to me. It is evident that the "posterior branch" is an indeterminate proliferation beyond the primary appendage, which appears to involve both the "median" and the "posterior" marginal series of the more normal forms. The receptacle, especially when a primary perithecium fails to develop, may become variously branched and more than one secondary perithecium may be produced. Antheridia of a type like that of Distichomyces appear to be developed externally on the posterior branch nearer the base. The specimens from Brazil and Trinidad seem to be identical, although those from Grenada, though otherwise similar, are constantly somewhat smaller. Rickia arachnoidea nov. sp. Basal cell rather short and stout, the receptacle above it dividing into two usually furcate arachnoid branches; an anterior on which a perithecium is produced, and a posterior. Anterior branch indeterminate, consisting of two parallel series of cells usually not opposite, irregularly appendiculate, furcate at a variable distance from its base; one of the branchlets sterile, often greatly elongated; the other short but variable, bearing a perithecium which on one side is usually united to the upper six cells, some of them appendiculate, which continue one of the two series forming the perithecial branchlet which thus extends to the apex of the perithecium, beside which it terminates in a short brown appendage: the perithecium long, slightly and nearly symmetrically inflated, the tip bent distally abruptly sidewise; the other row of the perithecial branchlet ending horizontally or obliquely below the base of the perithecium and consisting of from three to eight cells, some of which are appendiculate. Posterior branch indeterminate, furcate, usually, just above its first to fifth pair of cells, the cells of the two indeterminate branchlets not paired, irregularly appendiculate, indeterminate, usually greatly elongated: the second cell of the main receptacle below its furcation bearing the large long nearly cylindrical basal and subtending cells |