File:American malacological bulletin (1986) (17535719353).jpg

Title: American malacological bulletin
Identifier: americanmal4519861987amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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HOAGLAND: ENCAPSULATION IN CALYPTRAEIDAE 175 Crepipatella lingulata Gould from Southern California. The degree of development of the glandular region of the pallial oviduct and the number of seminal recepticles do not correlate with capsule shape, the type of eggs produced, or with the number of eggs per sac. Crepidula incurva (Broderip) and C. cf convexa (Fig. 2) of Caribbean Panama have planktonic and nonplanktonic development respectively, yet are antomically similar with respect to pallial oviduct and seminal recepticles. Both have a non-glandular region exten- ding anterior to the seminal recepticles and some seminal recepticles with short stalks. The major difference is that C. incurva tends to have more recepticles (5-6 instead of 2-4). Crepidula aculeata and C. lessonii have a similar pattern of development, yet differ strikingly in the glandular portion of the pallial oviduct (Figs. 1, 3). The process of encapsulation was first described by Werner (1948) for Crepidula fornicata. I have confirmed his observations for that species and for Crepidula plana Say, both of which produce numerous small eggs that complete their development in the plankton. Once fertilized and coated with yolk, the eggs travel into the muscular portion of the pallial oviduct. By this point they are grouped into sausage- shaped packets. The packets are expelled from the genital papilla and pressed to the base of the propodium (Fig. 4), then transported to the underside of the propodium in a ciliated track. When expelled, the packets are already sur- rounded by a thin membrane, but the origin of the capsule membrane is not known. The packets are next shaped by the propodium as it alternately contracts and stretches; at the end of this process, a stalk is drawn out from the packet membrane and the finished capsule (Fig. 5) is attached either to the hard substratum directly beneath the female, or to the propodium itself. The brood may consist of as many as 100 capsules, which fill the space between the neck lappets and propodium, and obscure the gill in ventral view (Fig. 4). Werner (1948) believed that the muscular portion of the pallial oviduct was responsible for formation of the egg packets. However, the Calyptraea, Crepipatella, and Crepidula aculeata all lack the muscular portion and indeed, the genital papilla. Their egg capsules have the same configuration as those of the species of Crepidula with these anatomical characters. Therefore, the muscular portion and the genital papilla are not essential for capsule formation. Werner (1948) noted that some gastropods have a foot Apo Pap
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0.5 mm i 1 Ppo Sr Ov Gp Fig. 1. Female reproductive system of Crepidula lessonii (Broderip) from Panama. Apo = Anterior pallial oviduct; Pap = genital papilla; Mpo = medial pallial oviduct; Ppo = posterior pallial oviduct; Sr = seminal recepticles; Gp = gono-pericardial duct; Ov = oviduct.

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