Monographs Details: Spermothamnion gymnocarpum M.Howe
Authority: Britton, Nathaniel L. & Millspaugh, Charles F. 1920. The Bahama Flora.
Family:Ceramiaceae
Description:Species Description - Indian lake or purplisli-vinaceous, fading to brownish-vinaeeous, grayishvinaceous, or vinaceous-fawn, forming rather dense cushions 1-3 cm. deep or somewhat straggling in habit ; primary creeping filaments 50-130 µ in diameter, their cells 130 400 fi long, mostly 3-5 times as long as broad, their walls 13-50 µ thick, the erect branches arising mostly from near the end of the cell ; erect filaments 50-115 µ. in diameter, rather freely subdichotomously, alternately, or subsceundly branched, rarely with 3 or 4 branches at a node, the branches patent or erecto-patent, arising subterminally or laterally just below the septum, the cells 300-750 µ long, mostly 3-7 times as long as broad, cylindric or slightly enlarged at upper end, the walls 5-40 µ thick, the terminal cells 40-65 µ in diameter, obtuse, or in the more branched conditions often only 12-15 µ in diameter with walls only 1-2 µ thick; chromatophores suborbicular, elliptic, fusiform, substellate, or difform, more or less confluent discs 2-13 µ in maximum diameter ; monoieous (polyoicous ?) ; procarps and cystocarps solitary or several closely approximate ; procarps subglobose or hemispheric, 40-50 µ broad, the trichogyne 10-13 µ in diameter; cystocarps moriform or irregularly hemispheric, 80-150 µ broad, wholly destitute of an involucre ; antheridial stands ovoid to subcylindric, 40-80 µ X 26-40 µ tetrasporangia borne on one-celled pedicels at nodes in distal parts of the main erect filaments and their branches, solitary or more often 2-5 at a node and aggregated on the inner side, or subverticillate, subglobose, 60-80 µ in diameter, their walls 5-12 µ thick.

Discussion:

On and with various other algae (Junta, Laurencia, Chamaedoris, etc.), in shal low water and washed ashore, Great Bahama (Hoicc 3879 type) and Exuina Chain. The species is perhaps related to the European S. irregulare (J. Ag.) Ardiss., but manifestlv differs in its longer, less ventricose cells, naked cystocarps. etc. Most of the few antheridial stands seen have been very close to the procarps, but the procarps preponderate so much in number that it may be suspected that dioicous conditions also occur.