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ADVANCES IN A MONOGRAPH OF THE GENUS GRACILARIA (RHODOPHYTA) IN THE MEXICAN ATLANTIC
Author(s) -
Dreckmann K. M.,
De LaraIsassi G.,
AlvarezHernández S.
Publication year - 2000
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.1999.00001-55.x
Subject(s) - holdfast , biology , thallus , botany , herbarium , taxon , genus , gracilaria , taxonomy (biology) , algae
Some species of the genus Gracilaria Greville (Gracilariales, Rhodophyta) are the main source of agar. For that reason, the taxonomic study of the taxon has become relevant for many scholars. In order to bring the Mexican floristics knowledge of the genus into the state‐of‐the‐art about it, we have initiated the needed monography. The character definition has proved to be the most important task. We have found that the most reliable characters for the species delimitation are: general form of the thallus, length and width; form of the axes, length and width; branching pattern; number of axes from the holdfast; form of the holdfast; presence of constrictions at the base of the branches or not; color; length of the segments; consistency; form of the apices; length and thickness of the stipes; surface texture of the branches, smooth, crispidous, etc; adherency to herbarium paper; cellular forms of the transition from cortex to medulla, size and thickness of celular walls of the cells involved; number of celular layers of the cortex, subcortex (if present) and medulla; form, number and distribution of the spermatangial conceptacles; form and size of the cystocarps, if constricted at the base or sessile; diameter of the ostiole and if it is apiculated or not; disposition of the carposporangial chains; form of the gonimoblastic cells, and form and number of tetrasporangia. A diagramatic description for each is provided.