Dwarf males in the barnacle Alepas pacifica Pilsbry, 1907 (Thoracica, Lepadidae), a symbiont of jellyfish

in Crustaceana
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In the pedunculate barnacle Alepas pacifica Pilsbry, 1907, a symbiont of jellyfish, several small individuals were found attached to conspecifics rather than directly to the host. We investigated whether these individuals act as dwarf males, as is known in some other species of barnacles. The conspecific-attached individuals had longer penes than juvenile hermaphrodites of similar sizes attached directly to the jellyfish, although there was no other morphological difference between these two types of individuals. Only the largest conspecific-attached individual was ovigerous. We conclude that the conspecific-attached individuals are dwarf males, which develop the male function at a smaller size than hermaphrodites do, with a small possibility of becoming hermaphroditic. This is the first report of dwarf males, and hence of the coexistence of males and hermaphrodites (androdioecy), in the family Lepadidae. In addition, the record of A. pacifica attached to Nemopilema nomurai Kishinouye, 1922, is reported herein as new to science.

Dwarf males in the barnacle Alepas pacifica Pilsbry, 1907 (Thoracica, Lepadidae), a symbiont of jellyfish

in Crustaceana



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    A, Part of the jellyfish Nemopilema nomurai Kishinouye, 1922 (host ID = 1) showing a distant distribution of the barnacle Alepas pacifica Pilsbry, 1907 (attachment site is indicated by the arrowhead); B, the largest individual of A. pacifica in A, removed from the jellyfish, with 14 small individuals attached to it. The largest conspecific-attached individual was ovigerous. This figure is published in colour in the online edition of this journal, which can be accessed via http://booksandjournals.brillonline.com/content/journals/15685403.

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    Alepas pacifica Pilsbry, 1907. Relationship between capitulum length (mm) and penis length (mm) for conspecific- (open circles) and jellyfish-attached (closed circles) individuals with a capitulum length of less than 6 mm.


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