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Affinities of the freshwater red alga Audouinella macrospora (Florideophyceae, Rhodophyta) and related forms based on ssu rrna gene sequence analysis and pit plug ultrastructure
Author(s) -
Pueschel Curt M.,
Saunders Gary W.,
West John A.
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.1529-8817.2000.99173.x
Subject(s) - biology , thallus , ultrastructure , affinities , sponge , botany , sporangium , spore , biochemistry
Small subunit rDNA sequencing and transmission electron microscopy were performed to clarify the ordinal affinities of Audouinella macrospora (Wood) Sheath et Burkholder isolates 3394, 3395, and 3603, as well as Chantransia sp. isolate 3585. Culture 3603 is known to produce thalli of Batrachospermum ‐like morphology under certain culture conditions. Sequence analyses unequivocally placed the three Audouinella macrospora isolates in a clade with Batrachospermum macrosporum Montagne of the Batrachospermales, and Chantransia sp. was found to have affinities with B. louisianae Skuja and B. virgato‐decaisneanum Sirodot. The pit plugs of the Audouinella macrospora cultures 3394 and 3395 were nearly identical in size and structure, having thickened plug caps and no cap membranes. Both of these features agree with those of the Batrachospermaceae, with the latter feature showing batrachospermacean rather than acrochaetioid affinities. Pit plugs in the chantransia phase of 3603 were similar, but the plug caps were less well developed. The Batrachospermum phase generated from 3603 had pit plugs that were variable in diameter, according to location in the thallus, thus reflecting the more variable cell size in this phase. Dome‐like outer caps, considered typical of Batrachospermum , were present between cells of the determinate lateral filaments. The pit plugs of Chantransia sp. had prominent, dome‐like outer caps, but the plug cores were strikingly and consistently smaller in diameter than those of the A. macrospora chantransia cultures, suggesting that plug diameter may be of systematic value in some contexts.