我国西沙群岛海藻的研究I．殖丝藻属

The reproductive feature of the nemalionalean genus Liagora is characterized by the laterally situated carpogonial branch which is produced by the ordinarily assi- milative filament.  A study of L. farinosa Lamx. has revealed that the carpogonial branches of this species are not borne on the  ordinarily  assimilative  filaments  but restricted to a kind of short filaments (referring to as “fertile filaments”  in the present article) which are, in turn, initiated by the basal cells of the assimilative filaments.  The carpogonial branches are modified furcations of the fertile filaments. The fertile filaments may, however, grow and send out assimilative filaments concur- rently with the maturation of the carpogonial branches.  Therefore, the origin of the carpogonial branches is best shown in their younger developing stages but more or less obscure in age.      Boergesen, who examined Lamouroux's type, made a detailed study of L. farinosa from the Canary Islands.  The depictions given by Boergesen, Yamada (1938, f. 15), Tseng (1941, f. 6) and Umezaki (1961, f. lA) concisely illustrated the feature of the fertile filaments in this species, although all these workers had not envisaged the taxonomical significance of the peculiar position of the female organs.  In our opin- ion, the differentiation of cortical filaments into assimilative and reproductive as seen in L. farinosa (even though in a preliminary stage)  suggests that the progressive evolutionary changes have occurred in this species.  The unique situation of L. fari- nosa is, in fact, no parallel in any genus of the, family where female organs are directly produced (or transformed) by the assimilative filaments.       It thus appears there is no justification for retaining L. farinosa in the genus Liagora.  A new genus, Ganonema Fan et Wang gen. nov. is therefore proposedfor accommodating the species, G. farinosa (Lamx.) Fan et Wang comb. nov.