NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 23 



Acrochaetlum rhizoideum (Drew) G. M. Smith 



Smith, 1944, p. 180. Rhodochorton rhizoideum Drew, 1928, p. 182, 

 pi. 42, figs. 42-44. 



Thalli endophytic in Codium, consisting of an endophytic system of 

 extensively developed rhizoidal filaments and densely tufted free fila- 

 ments 1.5-2 (3) mm. long; free filaments arising as branches from the 

 endophytic filaments, branched primarily from near the base but without 

 any regular order, above with scattered short branchlets, often in inter- 

 rupted secund series; cells cylindrical, decreasing slightly in diameter 

 toward the tips, 12-16 /* in diameter, mostly about 3 times as long; re- 

 production by monospores ; sporangia terminal and lateral on the branch- 

 lets, rarely sessile, ovoid, 16-20 by 22-30 /x.; sexual reproduction un- 

 known. 



Type : Holotype is Drew 392 on sheet 294553 in the Herbarium of 

 the University of California, Berkeley. 



Type locality: Santa Catalina Island, California. 



Mexican distribution : Pacific Baja Calif. — D. 9084, on Codium 

 fragile, Islas San Benito, Apr.; D. 10557, on Codiutn hubbsiij D. 

 10512a, on Codium fragile, Punta Norte, Isla Cedros, Oct. 



Acrochaetium bornetii Papenfuss 



Papenfuss, 1945, p. 313. Rhodochorton corymbiferum (Thur.) 

 Drew, 1928, p. 183-184. Acrochaetium corymbiferum (Thur.) Batters, 

 as employed by Hamel, 1928, p. 121-124, fig. 25; Newton, 1931, p. 255, 

 fig. 155. 



Thalli endophytic, the germinating spore giving rise both to branched 

 erect and penetrating filaments; erect, free filaments to about 2 mm. 

 long, slender, straight ; branches few below, more abundant above, alter- 

 nate or somewhat secund, with narrow angles, mostly 6-7 /a in diameter, 

 the cells mostly 5-10 diameters long; reproduction both sexual and by 

 monospores on the dioecious sexual plants ; sporangia long-ovate, 7-8 \x. in 

 diameter, solitary and sessile or 2 or 3 together on 1 -celled pedicels; 

 antheridia and carposporangia borne in short-pedicellate corymbose 

 clusters. 



Type : Holotype is the specimen collected by G. Thuret in August 

 1851 growing on Helminthocladia calvadosii (Lamour.) Setch. (=H. 

 purpurea), in the Herbarium of the Museum d'Histoire Naturelle, 

 Paris. 



Type locality: Belle-Ile-en-Mer (Morbihan), France. 



