KEY TO DERMATOLITHON' 



275 



15. Hypothallium cells long, mostly 60 to 115 /a; tetrasporangial 

 conceptacles 200 to 320 /x in diameter . . . . D. ascripticium 

 (Foslie) Setchell and Mason (1943) = Lithophyllum pustu- 

 latum f. ascripiicia Foslie (1907) Type locality: California, 

 U.S.A. 

 15. Hypothallium cells shorter, mostly 30 to 65 ji long; tetraspor- 

 angial conceptacles mostly over 320 fi in diameter .... 16 

 16. Asexual conceptacles 200 to 600 fi in outside diameter, ^^-ith 

 tetrasporangia or bisporangia^ . . . . D. pustulatum (La- 

 mouroux) Foslie (1900a) = Melobesia pustulate La- 

 mouroux (1816) Type locality: Europe 

 16. Asexual conceptacles mostly 300 to 450 ^ in outside diam- 

 eter, mainly with bisporangia . . . . D. litorale (Suneson) 

 Hamel et Lemoine (1953) = Lithophyllum litorale Sune- 

 son (1943) Type locality : Sweden 

 1 7. Thalli completely encasing extensive parts of host algae ; hypo- 

 thallium cells usually 54 to 90 ji long, seldom less than 54 p. 

 long; conceptacles convex and more or less prominent . . . . D. 

 polyclonum (Foslie) Foslie (1909) = Lithophyllum (Derma- 

 tolithon) polyclonum Foslie (1905) Type locality: West Indies 

 17. Thalli encrusting or partially encasing host algae : hypothallium 



cells often less than 50 {x long 1° 



18. Conceptacles immersed or only slightly prominent ... 19 

 18. Conceptacles forming "very low, small warts;" epiphytic 

 on Carpophyllum in New Zealand . . . , D. carpophylli 

 (Heydrich) Foslie (1909) = Melobesia carpophylli 

 Heydrich ( 1893) Type locality: New Zealand 

 19. Hypothallium cells 18 to 30 ju. long, not particularly variable in 

 length in different parts of the thallus ; conceptacles 200 to 250 

 /Li in diameter, 125 /u. high; plants growing on Gelidium .... 

 D. tumidulum (Foslie) Foslie (1909) = Lithophyllum tumi- 

 dulum Foslie (1901) Type locality : Japan 

 19. Hypothallium cells mostly over 30 ju. long, very variable in 



length in dififerent parts of thallus 20 



20. Hypothallium cells 10 to 50 ju, long; tetrasporangial con- 

 ceptacles 90 to 150 ju, in diameter; plants growing on 

 Laminaria . . . . D. crouanii (Foslie) Hamel et Lemoine 

 (1953) = Lithophyllum crouani Foslie (1898) Type lo- 

 cality : France 



WermatoUthon macro car pum (Rosanoff) Foslie is now generally considered to 

 be a bisporic form of D. pustulatum. 



