In the southeastern Pacific Ocean off Chilean coasts some salp solitary zooids were found showing the main features of Helicosalpa younti Kashkina 1973, excepting the arrangement of the light organs is like its close relative H. virgula. H. younti was created by van Soest
(1974) based upon the descriptions from the literature of two solitary zooids, but very important diagnostic characters as the number of muscle fibers were unknown, and aggregate zooids were not described. In the Chilean coasts samples, many aggregate zooids were found which are also described
making special mention of characteristics not known for H. younti (e.g., dorsal tubercle and muscle fiber number). The differences in muscle fiber number of both solitary and aggregate zooids, which surpass considerably any number known from H. virgule, added to details of the
intermediate muscle arrangement in the solitary zooids, seem to justify the permanence of H. younti as a valid taxon. The arrangement of the light organs may be a variable feature within a salp species or perhaps, more likely, subject to post-preservation artifactual changes. Another
feature traditionally employed in species differentiation, the morphology of the dorsal tubercle, is variable with the specimen size.
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