Fertilization in the white chiton, Stenosemus albus, with implications for its phylogenetic position
Gamete structure and fertilization biology of the white chiton, Stenosemus albus (L., 1767), were studied with light and electron microscopy. Sperm structure was found to be similar to other Chitonina, but acrosomes are homogeneous in this species, like those of Chaetopleura apiculata (Say in Conrad...
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Published in | Canadian journal of zoology Vol. 86; no. 9; pp. 1024 - 1030 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Ottawa
National Research Council of Canada
01.09.2008
NRC Research Press Canadian Science Publishing NRC Research Press |
Subjects | |
Online Access | Get full text |
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Summary: | Gamete structure and fertilization biology of the white chiton, Stenosemus albus (L., 1767), were studied with light and electron microscopy. Sperm structure was found to be similar to other Chitonina, but acrosomes are homogeneous in this species, like those of
Chaetopleura apiculata
(Say in Conrad, 1834). The egg of S. albus is covered by long spines with hooked tips. The bases of spines are perforated along their perimeters by a series of pores that provide sperm with direct access to the vitelline layer. This feature appears to be plesiomorphic and characterizes also Chaetopleura but not most Chitonina, which have a continuous dense layer overlying the hull. Beneath the vitelline layer, the egg membrane is formed into a series of cups with raised edges elaborated into microvilli that coincide with the bases of hull spines. Free-spawned sperm of S. albus were able to find the egg and penetrate a pore in the hull within 20 s. Evidence presented here, and previously, indicates that S. albus shares a number of key characters in common with Callochitonidae, which is a basal family within Chitonida. Taken together, the evidence suggests that Stenosemus belongs to a basal taxon within Chitonina, outside the Ischnochitoninae, in which it is currently placed. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0008-4301 1480-3283 1480-3283 0008-4301 |
DOI: | 10.1139/Z08-082 |