s 



PROCEEDINGS OF THE NATIONAL MUSEUM 



Table 3. — Comparative measurements (in microns) of five specimens of Loxosomella 

 tedaniae, new species (BE 45/6 = holotype) 



by the absence of the row of large gland cells on the back edge of 

 the lophophore, which is typical for L. tethyae, and by the presence of 

 conspicuous gland cells in the wings of the foot instead. 



Interspecific Relation Between Loxosomella and Host Sponge 



Large numbers of the following two loxosomatids also have been 

 reported to have covered sponges from Bogue Sound, near Beaufort, 

 N.C., by Nielsen (1966a): Loxosomella tethyae (Salensky) on Micro- 

 ciona prolifera (Ellis and Solander); and L. cricketae Nielsen on 

 Lissodendoryx isodictyalis (Carter), Adodia tubifera (George and Wil- 

 son), and Hymeniacidon heliophila (Parker). 



It has been noted before (Cori, 1936, p. 83) that loxosomatids 

 particularly dwell abundantly in stagnant or even polluted water. 

 This is true also of the specimens of Nielsen in North Carolina and 

 the present records. Most of the older findings in the Mediterranean 

 come from harbor areas such as Naples and Trieste. Ali (1960) reports 

 the common association between epi- and endobionts and sponges 

 as a characteristic feature of Madras harbor. A combination of factors 

 is likely to be responsible for this phenomenon. A certain resistance 

 against pollution must be assumed, and as ciliary detritus feeders, 

 the loxosomatids find most favorable feeding conditions in rather 

 stagnant and detritus-rich waters. Since, in such environments, the 

 high sedimentation rate (in connection with little water movement; 

 see Riitzler, 1965, p. 71) causes burying of all suitable dead sub- 

 strates or endangers survival by causing the animal to choke, sponges 

 must prove to be the most suitable hosts. It seems practical that those 

 species are selected (or act selective) that occur in abundance because 

 the loxosomatid larva has a very limited dispersal range (Nielsen, 

 1964, p. 73). By what chemical affinities the host specif! ty is estab- 

 lished and how they have evolved can not be determined in our 

 present state of knowledge. 



