ECOLOGY AND TAXONOMY OF HttUmeda 85 



C. Generic description of Halimeda Lamouroux,1812 : the circumscription 

 is emended to include uniaxial species 



Halimedea Lamouroux (1812), p. 186. 



Halimeda Lamouroux (1816), p. 302, nomen conservandum. 



Ormus Hill (1751), p. 12, Plate 3. 



Sertularia Boehmer ex Ludwig (1760), p. 504. 



Corallinap.p. Linnaeus (1758), p. 805; Pallas (1766), p. 420; Petiver (1767), 



Plate 20, Fig. 19; Ellis and Solander (1786), p. 108; Esper (1798-1806), 



Plate 11. 

 Flabellaria p.p Lamarck (1813), p. 302; Delle Cliiaie (1829), p. 9, Plate 10. 

 Fucusp.p. Bertolini (1819), pp. 224, 316. 

 Ulva p.p. Pollinius (1824), p. 507. 

 Codium p.p. Springel (1827), p. 366. 

 Opuntia p.p. Naccari (1828), p. 104. 

 Sertolara Nardo (1834), p. 673. 



Plants flaccid, prostrate or erect, and generally bushy, arising from a 

 filamentous holdfast system, usually not exceeding 25 cm in height although 

 to 1 m or more in sprawling specimens ; branches composed of linear series 

 of calcified segments, the nodes being uncalcified and flexible; segments 

 plane or ribbed, spherical, tear-shaped, compressed- cylindrical, or cuneate 

 to reniform in shape, with upper margins entire or lobed; organization 

 consisting of coenocytic filaments which produce a multiaxial or occasionally 

 a uniaxial core of medullary filaments surrounded by a cortex composed of 

 layers of utricles, the outer walls of the peripheral utricles forming a 

 continuous or slightly discontinuous surface ; the medullary filaments, when 

 more than one, remaining separate, or anastomosing in small groups, or into 

 a single large unit at the nodes, their walls generally thickened in these 

 regions ; sexual reproduction by biciliate gametes produced in large globular 

 to pyriform gametangia on stalks which are simple or branched, and arise 

 from the node, segment margin or surface. 



Lectotype species. Halimeda tuna (Ellis and Solander) Lamouroux. 



D. Description of the sections 



Five sections of the genus were delimited in Section III (including 

 Table V) on the basis of pattern of the medullary filaments at the node. 

 Their formal descriptions are given below. 



Section Rhipsalis J. Ag. ex De Toni 1889 as Rhipsales. Filaments of a 

 node fusing briefly into a single unit. 



Section Opuntia J. Ag. ex De Toni 1889 as Opuntiae. 



Most or all of the filaments of a node fusing briefly in pairs; 

 occasionally fusing in other units, or remaining single. 



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