ECOLOGY AND TAXONOMY OF Halimedu 55 



Table IV. The Categories of Halimeda Species Delimited by J. Agardh 

 (1887), Recognized as Sections by De Toni (1889) 



"Species, aegre characteribus circumscribendas, sequenti mode disponere conatus 

 sum: 



I. Tunae virescentes, parum incrustatae, adscendentes aut erectiusculae, 

 articulis planis enervibus, simplicibus discoideis, ramos generantibus 

 saepe subreniformibus, margine plerumque integerrimis." 

 H. tuna, H. papyracea, H. macroloba, {H. macrophysa") 



II. "Pseudo-opuntiae albescentes et evidentius incrustatae, diffusae aut stipi- 

 tatae articulis superioribus orbiculatis aut subreniformibus planis, 

 saepius enervibus et margine integerrimis, plerumque in longos ramos 

 simpliciusculos concatenatis." 

 H. gracilis, H. nervata, H. brevicaulis 



III. "Opuntiae albescentes et evidentius incrustatae, conglobatae aut diffusae, 



nvmc stipitatae, decomposito-ramoisissimae, articvilis superioribus 

 planis reniformibus, diametro transversali longitudinalem superante, 

 enervibus aut plus minus conspicue nervosis, nervis ad lobos marginis 

 superioris, saepe ramos plures generantes, excurrentibus." 

 H. cordata, H. opuntia (f. opuntia, f. trihola), H. incrassata (f. ovata, 

 f. Lamourouxii, f. tridentata) 



IV. "Rhipsales ex veridi aut cinereo albescentes et evidentius incrustatae, 



erectiusculae et saepius stipitatae, articulis aut teretiusculis, aut com- 

 planatis et a basi ctuieata dilatatis, diametre longitudinali transversalem 

 aequante aut superante." 



H. obovata, H. versatalis, H. tridens, H. cylindracea, H. monile, H. 

 polydactylis, (H. renschii'^) 



"Species mihi ignota 

 H. discoidea." 



" Species added by De Toni. 



The obvious character around which sections of the genus Halimeda 

 should evolve is that of medullary filament pattern at the nodes. This 

 character is the most important one in the taxonomy of the genus, and 

 so may be expected to reflect fundamental phyletic divergence. The 

 five groupings given in Table III, based on pattern of medullary 

 filaments, provide a logical framework for sections of the genus. Con- 

 sequently, I propose they be designated as sections, and called Rhip- 

 salis, Opuntia, Halimeda, Micronesicae and Crypticae. The nodal 

 structure on which they are based, and the species each contains, are 

 shown in Table V. Formal descriptions are given in Section IV. 



