Monographs Details: Anacystis gigas (West & G.S.West)
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Family:Microcystaceae
Description:Distribution and Ecology - Growing in company with other species of Myxophyceae on limestone, between Arecibo and Utuado, no. 1476; between Hatillo and Arecibo, no. 1387 b; on old wood at Hato Arriba, Arecibo, no. 1397 b; on a wall in Fort San Cristobal, San Juan, nos. 1991 c, 1993, 2002, 2003 d, 2008, 2014 c and 2021.

Discussion:

A large percentage of the species of IVtyxophyceae collected by Dr. Wille on Porto Eico are unicellular. Many of these species belong and may readily be associated with more or less well-recognized and clearly defined genera. Others seem decidedly to be allied with less clearly delimited genera and before these can be satisfactorily placed the limits of such genera must be either more clearly defined and amplified or new genera must be erected for their reception. In this instance I shall attempt the former procedure. Three of such genera are Chroococcus Naegeli, Gloeocapsa Kuetzing, and Anacystis Meneghini. Naegeli proposed the genus Chroococcus in 1849,2 selecting as the type of the genus C. rufescens (Pleurococcus rufescens Breb.) at the same time recognizing nine-other previously described species, which had been placed with one or the other of the genera Protococcus or Pleurococcus. All of these have since been very generally recognized as belonging to Chroococcus. Naegeli's conception of the genus as set forth in his diagnosis and in his discussion which follows seems to have been of a group whose cells exist either singly or, by division "in alien Richtungen des Raumes" and remaining for a time intact, become associated into small, spherical or cuboidal families, or colonies of 2—8 or, more rarely, 16-32 cells, surrounded by a thin colorless, homogeneous or at times slightly lamellose wall.

Although Naegeli states that the wall is thin, scarcely one-third the thickness of the lumen of the cell (a thick wall as compared to the cell proper) he undoubtedly meant thin as compared to that of Gloeocapsa, which he discusses in connection with Chroococcus, and which may become several times thicker than the lumen of the cell.

The genus Gloeocapsa was proposed by Kuetzing in 1843. He designated no type species, but the first species mentioned is G. montana, which may ordinarily be considered the type of a genus when no special one is proposed. His diagnosis of the genus is very brief and incomplete. In 1846,1 he illustrated the species.

The genus was reviewed by Naegeli (loc. cit.), who designated as the type G. at rat a Kuetz., which he redescribed and illustrated. I have examined bits of the type of both of these species and judging from these and from the descriptions and figures given by Kuetzing and Naegeli, both writers had practically the same conception so far as the type, G. atrata, is concerned. As pointed out by Naegeli and by subsequent writers, the two genera Chroococcus and Gloeocapsa undoubtedly overlap, and such forms as G. montana seem as clearly allied to the one as to the other. I am considering forms with a firm, smooth, hyaline wall, or tegument, with relatively few cells in a colony, and these remaining angular after division throughout the greater part of the life cycle of the colony, and such forms as remain within special teguments for several generations all remaining within a common, more or less gelatinous, original, copious tegument, becoming decidedly laniellose and often variously colored, and with cells soon becoming spherical after division, as the extremes respectively of the genera Chroococcus and Gloeocapsa, both together constituting a heterogeneous group. The two genera may be kept as conveniences rather than as distinct entities, and I have so considered them in placing the various specimens of the collection. The placing of Chroococcus limneticus Lemm. within that section of the group seems unwarranted since that species as described has the cells embedded within a copious gelatinous tegument.

My experience from examination of many collections and cultures of both Chroococcus and Gloeocapsa reveals the fact that they both have the same general method of multiplication, viz., at times certain single cells are liberated from a colony. These usually become spherical and by division start new colonies. However, never does the entire colony go into the one-celled stage simultaneously, the cells in groups of two, four, or more, enclosed within their special tegument, continuing to divide, becoming liberated from time to time by the dissolution of the outer common tegument.The genus Auacystis of Meneghini, 1837,5 has a very different and distinct method of multiplication. Starting with a single cell always, by repeated divisions, a colony, varying in size and shape according to the species but usually spherical in form, is evolved. At maturity, when the cells cease to divide, each cell in the colony develops simultaneously a special, often highly ornate, cell-wall, and the colonial tegument then dissolves and liberates these resting cells. Each again, after a period of rest, starts another colony. The life cycle is very distinct and definite.

This cycle, although not definitely outlined by Meneghini, was clearly indicated in his drawings {loc. cit.). I am here emending the genus to that extent. Naegeli (loc. cit., pi. 1, fig. F, 2-6) has included with the type of Gloeocapsa organisms which, from the appearance of the drawings, have a life cycle not that of the type which he designated, but that of Anacystis.

I am excluding such species from the genus Gloeocapsa even though some species may have differentiated teguments within the colonial tegument, and thus emending the genus as understood by Naegeli and followed by later writers. The inclusion of such forms undoubtedly has led to the statement that resting spores are produced by certain species of Gloeocapsa. "West's Gloeocapsa gigas from the AVest Indies clearly belongs to the Anacystis lineage.

Setchell and Gardner have shown that Kuetzing's Microcystis, 1833, was not homogeneous and most of its species are to be referred to a different group of organisms from the Myxophyceae.