Nemertina
Identification of pelagic nemertines

Although histological studies are ideally required for the certain identification of pelagic nemertines, individuals can often be placed in families on the basis of either external features or internal structures visible in whole mount specimens, especially when stained and cleared. Coe (1954a, 1956) provided keys to the Pacific and North Atlantic families respectively in which he distinguished between them by such features as the presence or absence of anterior tentacles, the length of the mid-dorsal blood vessel, the number and arrangement of the intestinal diverticula and whether or not they possess distinct ventral branches, the shape of the body (i.e., broad and flattened or slender and rounded), and the development of external phalli on the male gonads (spermaries). Anatomical features of pelagic nemertines which can be used in their identification are illustrated on page Ne. 6 Morphological and anatomical features.

Bathypelagic nemertines have been relatively little investigated from the South Atlantic in comparison with other oceanic regions; for example, representatives of all 11 families have been recorded from the North Atlantic, with a total of 44 known species from 26 genera (45% of the world's known species), whereas in the South Atlantic the 11 reported species are from 6 genera and only 4 families. No examples from the families Armaueriidae, Balaenanemertidae, Buergeriellidae, Chuniellidae, Dinonemertidae, Pachynemertidae or Phallonemertidae have yet been found in the South Atlantic.

On Page 358: Nemertina a key is provided to the families, genera and species of pelagic nemertines recorded from the South Atlantic and brief diagnoses for each taxon are given. Other species will undoubtedly be discovered during future oceanographic surveys. Where the name of the species in current use differs from that recognised by Korotkevich (1955a, 1977a) the alternative name is indicated.