ECOLOGY AND TAXONOMY OF HttUmeda 139 



specimens intermediate between f. discoidea and f. subdigitata. Consis- 

 tent with the treatment accorded entities based mainly on modifications 

 of habit or segment morphology which seem unaccompanied by 

 significant histological differences, these three have not been given 

 separate taxonomic standing. The type of the subspecific taxon 

 H. cuneata f. digitata has not been located with certainty. It does not 

 appear to belong to cuneata, as already mentioned, and is retained in 

 sjmonymy with discoidea where it was tentatively placed by Hillis 

 (1959). 



Halimeda taenicola W. R. Taylor 



Figure 42. 



Halimeda taenicola Taylor (1950), p. 86, Plate 46. Fig. 1; Hillis (1959), 

 p. 354, Plates 2, 5, 6, 11. 



Plants erect and compact, arising from a small holdfast region, to 15 cm 

 tall; calcification moderate; the surface generally glossy and smooth but 

 sometimes rugose ; branches numerous with up to five arising from a single 

 segment; the lowermost one to two segments usually compressed- cylindrical 

 to subcuneate and often of a substipitate nature, others plane, often becoming 

 concave on drying, generally subcuneate to trapezoidal, less commonly 

 subcylindrical or reniform, the upper margin entire, to 11 mm long, 18 mm 

 broad, and averaging 1-0-1 -5 mm in thickness. 



Cortex of two to three layers of utricles; outermost utricles remaining 

 firmly attached after decalcification for an average distance of 19 \uxi, 

 sometimes fusing laterally in twos and threes for this same distance, unfused 

 peripheral utricles (20-)40-75(-86) [jim in surface diameter, (45-)56- 

 125(-140) [zm long in section, their lateral and peripheral margins sometimes 

 thickened, four or occasionally up to six supported by each secondary 

 utricle ; if three layers of utricles present the secondary ones relatively small, 

 26-60(-80) (Jim broad, (30-)40-90 ^m long; innermost utricles usually 

 relatively large, 75-160(-190) jj,m broad. 



Nodal medullary filaments generally uniting completely in twos and 

 threes; fused units entangled and adhering laterally for 40-70 [xm. 



Type specimen. Marshall Islands, Rongerick, Enyvertik Island, 

 Taylor 46-551, 29 June, 1946 (MICH). 



Habitat. The known depth range is — 1 m to — 47 m. At 

 Enewetak this species occupied microsites in the fast-flowing 

 inter-island channels similar to those filled by lacunalis f. lata, but 

 taenicola was less common. These sites were the seaward and lee- 

 ward faces of the coral rock on which the thalli were growing, often 

 tucked into microcaves or attached near the eroded bases of the 

 rock, under miniature overhangs (Section X). 



