6926475879

V

198    Arquivos

is generally situated in its middle-right region, in contrast with stornach of basal caenogastropods (littorinids, hydrobioids) in which the esophagus aperture is almost at the same level as the style sac. The anterior migration of the esophageal aperture is only found in Alaba and Batillaria among the examined cerithioideans. Serpulorbis, in contrast, has a posterior esophageal aperture.

105.    Digestive gland: 0= single; 1= double {Serpulorbis decussatuś) (CI= 100, Rl- 100).

See comments in character 92.

106.    Digestive gland anterior limit: 0= anterior to stornach; 1= middle (thiarids, pleurocerids, Turritella hookeri, cerithids, Finella dubia, Alaba incerta, Batillaria minima, Cerithidea costata), 2= posterior (Supplanaxis nucleus) (Cl= 50, RI- 71, not additive).

107.    Intestinal loops: 0= several; 1= up to two (thiarids, Supplanaxis nucleus, pleurocerids, cerithids, Finella dubia, Alaba incerta, Cerithidea costala) (Cl= 100, Rl= 100).

Cenital system

108.    Gonad site: 0= around digestive gland; 1 = superior region of digestive gland only (all cerithioideans) (not cxamined in Campanile symbolicum) (CI= 100, RI= 100).

109.    Pallial oviduct: 0= simple groove; 1 = glandu-lar groove (probably with a chamber in each lamina) (all cerithioideans) (CI= 100, Rh= 100).

110.    Chamber in outer lamina of pallial oviduct: 0= single; 1= nonę (pleurocerids, Cerithium atratum, Cerithidea costata, Campanile symbolicum) (Cl= 25, Rl= 50).

111.    Chamber in inner lamina of pallial oviduct: 0- single, 1= nonę (Aylacostoma exoplicata, A. ci, Melanoides tuberculatus, Finella dubia, Campanile symbolicum, Serpulorbis decussatus); 2= double (Supplanaxis nucleus, cerithids) (CI= 28, RI= 28, not additive).

112.    Some genital chamber outside of oviduct: 0-

de Zoologia

absent; 1= in kidney {Cerithium atratum)-, 2-in pericardium {Campanile symbolicum) (CI= 100, RI= 100, not additive).

These States are not homologous, as confirmed by the tree, and are regarded as not additive.

113. Degreeofclosureof pallial oviduct: 0: alrnost entirely open (a furrow); 1= posterior half closed (a half tubę) {Aylacostoma spp); 2= entirely closed (a tubę) {Melanoides tuberculatus) (CH 33, Rl= 55, additive).

The open condition of cerithioidean pallial gonoducts has been regarded as secondary by some authors, i.e., derived from closed ducts (Fretter 1951: 583; Johansson 1956; Houbrick 1988). This possibility obviously exists, but cannot be advocated “a priori”. Within and outside cerithioideans both conditions occur. Within cerithioideans most taxa have both spermduct and oviduct alrnost entirely open (a short region in posterior extremity is closed), but closure in different degrees, from half- to entirely closed, occur in Thiaridae and Cerithideidae. In other Caenogastropoda, open pallial oviducts are uncommon, occurring in some Littorinoidea and Rissoidae (Johansson 1956; Ponder 1976) and strombids (person, obs). On the other hand, open pallial spermducts are common, Tonnidae and 01ividae, for example, have it entirely open (Marcus & Marcus 1959; Simone 1995b; person, obs.). Costellariidae have it partially opened (Ponder 1972; Simone 1995c). Pallial gonoducts also occur in other groups beyond caenogastropods, such as Cocculiniformia, Neritimorpha and Architaenioglossa and basal Heterobranchia, Comparison is difficult as homology of these structures is uncertain, and both conditions, open and closed, occur. In the present analysis the open condition is regarded as plesiomorphic, in agreement with Haszprunar (1988: 388).

The pallial oviduct, in cerithioideans, is morę than a single groove. All examined species have a very glandular pallial oviduct and sometimes it has other glands and chambers (receptaele, bursa and others). The presence and the number of accessory structures in the inner and outer lamina of pallial oviduct appears to be of great value in species comparison, but of little value at higher levels. Several conditions can be found in species of the same group (see, e.g., Houbrick, 1992a). The