(a) 



IP 



I 



cuneata 



lacunalis 

 macrophysa 



tuna 



Section Halimeda 

 discoidea 



I 

 I 

 P 



\ 



A 



I 



scabra 



gigas 



P 

 I 



taenicola 



gracilis 



T^N 



A 



I 



lacrimosa 



bikinensis 



(b) 



simulans 



Section Rhipsalis 

 incrassata 



praemonilis 



macroloba 



borneensis 



---'T^--^ 



A IP A 



I 

 favulosa cylindracea monile 



stuposa 



(c) 



Section Micronesicoe Section Crypticae 



Fig. 76. Hypothetical lineages of Halimeda species from the pantropical modem and 

 fossil species named in the boxes, (a) Species erect or pendant from rock except 

 gracilis; holdfast usually ^1 cm long, (b) Sand-"rooted" species; holdfast usually 

 > 1 cm long, (c) Species that sprawl or creep; often more than one point of attach- 

 ment on a thallus. IP = Indo-Pacific; P = Pacific; A = Atlantic distributions as 

 currently known. 



