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|Title: ||Distribution, adult morphology and larval development of Sacculina sinensis Boschma 1933 (Cirripedia: Rhizocephala: Kentrogonida) in Hong Kong.|
|Authors: ||Benny Kwok Kan Chan;David Yiu Nam Poon;Graham Walker|
|Issue Date: ||2018-05-14T06:31:11Z
|Publisher: ||Journal of Crustacean Biology|
|Abstract: ||Abstract: Sacculina sinensis (Cirripedia: Rhizocephala) is a parasitic barnacle first reported in Hong Kong by Boschma (1933) to infect the intertidal crab, Leptodius exaratus. Since then, no studies have been conducted to investigate its distribution and morphology, which are important in providing background information for further taxonomic and ecological studies. In the present study, S. sinensis has shown to have a limited distribution in Hong Kong, being confined to only four out of the nine sheltered boulder shores sampled and with a mean infestation rate of
percent. The localized distribution of S. sinensis in Hong Kong is probably due to its short larval development times (four naupliar stages and one cypris stage, completed in about six days) and hence limited larval dispersal distance. The externa of S. sinensis is ovoid in shape with two distinct shoulders, and the outer cuticle surface is spinous. From histological studies, the male receptacles are located posteriorly in the visceral mass, and each male receptacle is globular in shape. The receptacle duct is folded and connected to the receptacle via a small tube with a thick cuticle lining. The larval morphology of S. sinensis was investigated using a scanning electron microscope. The appendages bear setulate setae in all naupliar stages. In the cyprid, segment III of the antennule consists of the attachment disc in both sexes, and the male has a large posterior aesthetasc which is absent in females. On segment IV, male cyprids have a large terminal aesthetasc, a subterminal aesthetasc, and three terminal setae. Segment IV of female cyprids has a subterminal aesthetasc which is smaller than that on the male cyprids. The larval sex ratio showed seasonal variation with 100 percent males in summer and 80 percent females in winter. Such seasonal variation in sex ratio would allow the female cyprids to infest the host crabs in winter, producing virgin externae by summer for the male cyprids to settle, and allow the externae to mature.
|Relation: ||25(1) pp.1-10|
|Appears in Collections:||[海洋生物研究所] 期刊論文|
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