12 . SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES 



conceptacle. Whereas sexual and cystocarpic gametangial con- 

 ceptacles have a single large pore at their apex, asexual sporan- 

 gial conceptacles are multipored. 



Sporangial (apparently diploid) plants (with abundant bi- 

 or tetrasporangium-bearing conceptacles) are seasonally com- 

 mon among the principal Clathroviorphum species, whereas 

 gametangial plants (apparently haploid male and female) and 

 conceptacles are more or less rare. Adey (1965) examined re- 

 production in C. compactiiDi, and Lebednik (1976) extensively 

 studied reproduction in C. nereostratiiin. Herein we provide ad- 

 ditional information for both species. The earlier work by Adey 

 and Lebednik was accomplished with decalcified material stud- 

 ied with light microscopes. Here we emphasize SEM sections, 

 observing the conceptacles as they occur buried in the fully calci- 

 fied skeleton. The diameter and height of sporangial conceptacles 

 for both species and for sexual conceptacles of C. nereostratiim 

 are given in Figure 7. Complete dimensional analyses of surficial. 



mature conceptacles, with roof dimensions and burial depth at 

 maturity, are provided in Adey (1965) and Lebednik (1976). 

 Since gametangial conceptacles develop in spring rather than 

 autumn (when sporangial conceptacles develop), distinguishing 

 between them may be necessary in temporal analyses of tissue 

 chemical composition. 



Adey (1965; for C. cumpactiim) and Lebednik (1976; for 

 C. nereostratum) provided photographic images of several stages 

 of development of sporangial conceptacles. However, neither au- 

 thor showed the details of development, particularly relative to 

 the simultaneous and essential growth in vegetative tissue, that 

 are required for understanding the relationship between anat- 

 omy and seasonality. This information is potentially important 

 in climate archiving for determining the seasonality of carbonate 

 deposition in each vegetative cell. Figure 8 shows the stages of 

 development of sporangial conceptacles in C. compactum rela- 

 tive to the surrounding vegetative tissue. Developmental stages 



400 -, 



350- 



300- 



250 



^ 200 



O 



150 



O 



O 100 



C. nereo 

 C. comp N. Lab 

 C. comp S. Lab 

 C. comp NENF 

 C.comp. GOM 



C. nereo mean 



. comp rri«afr(excluding GOM) 



50- 



— I — . — \ — I — I — I — I — I — I — . — I — I — I — I — I — I — I — . — I 

 50 100 150 200 250 300 350 400 450 500 



Conceptacle Diameter (^m) 



FIGURE 7. Dmiensions of mature conceptacles of C. compactum (105 conceptacles, 13 plants, and 9 stations) 

 and C. nereostratum (84 conceptacles, 11 plants, and 7 stations). Colored squares are means of individual 

 plants. Female conceptacle data are for C. nereostratum Lebednik, 1976. Male and cystocarpic data are derived 

 from a combination of this study and Lebednik (1976). The long arrow describes the path of development of 

 C. nereostratum female conceptacles, from unfertilized carpogonia through postfertilization to mature 

 carposporangia. 



