Opisthobranch ova & capsules

October 21, 2000
From: Cynthia Trowbridge

Dear Bill,

Hi. Yet another query that has long puzzled me. I have tabulated the number of ova per capsule in NE Pacific sacoglossans (ascoglossans) . Most species have just one per capsule. But, there are at least 4 species that have more than one:

Lobiger souverbiei - up to 5
Elysia hedgpethi - 1-2
Elysia diomedea - 6-14
Stiliger fuscovittatus - 1-2

I was wondering if there was any biological significance for the inter-specific variation or the intra-specific variation? The latter is particularly troubling to me, particularly after reading an account for S. fuscovittatus that cases with 2 ova per capsule do not develop. Some of the variation is within individual egg masses. Has anyone ever noted that sacoglossans with multiple embryos per capsule do actually develop? Has anyone noted the intra-specific phenomena in other opisthobranchs?

Any thoughts or suggestions would be much appreciated!!
Cheers,
Cynthia

trowbric@ucs.orst.edu

Trowbridge, C., 2000 (Oct 21) Opisthobranch ova & capsules. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3132

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