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Arquivos de Zoologia

89. Middle esophagus inner surface: 0= transver-sal folds; 1 = papillate (pleurocerids); 2= lon-gitudinal folds (thiarids, Bitłium varium, Finella dubia, Cerithidea costata, Campanile symbolicum); 3= smooth (Serpulorbis decussatus) (CI= 37, RI= 54, not additive).

93. Central pad: 0= absent; 1= flap-like (Turritella j hookeri, M. modulus, Campanile j symbolicum, Serpulorbis decussatus); 2= broad fold (remaining cerithioideans); 3= with acinous lobe (Doryssa atra, D. macapa) (CI= 100, RI= 100, additive).

90.    Pouch form: 0= open; 1= smali lobes

{Campanile symbolicum) (Cl= 100, RI= 100).

91.    Glandular tissue: 0= present; 1= absent (all

cerithioideans except M. modulus) (Cl- 50,

RI= 75).

The esophagus with a pair of glandular pouches is found among vetigastropods (e.g., Haliotis, Pleumtomaria, person, obs.) and in some cerithioideans. This condition is regarded as plesiomorphic. However, elear glandular pouches are only found in Modulus; the other cerithioideans having a pair of pouches, there are only oblique folds, without elear glandular tissue (the walls are thin). Two other esophageal conditions occur among cerithioideans. The first is that of pleurocerids (Abbott, 1955; this study), which have only one large pouch lined intemally by tali papillae (similar to those which occur in inner surface of pouches of the vetigastropods). The other derived condition is the esophagus being a single tubę, presenting, at most, longitudinal folds. This is found in thiarids, Bitłium, Finella, Cerithidea and Serpulorbis. In Campanile, the pouches are reduced and differentiated, becoming two semispherical chambers situated laterally anterior to the ncrve ring; apparently the Campanile pouches are homologous to pouches of other cerithioideans as well as of the littorinids (Simone, 1998) and architaenioglossans (Ponder & Lindberg, 1997).

Stornach

92.    Width: 0= narrow; 1=broad (all cerithioideans)

(CI= 100, RI= 100).

The stomachs of cerithioideans are characteristically very large - almost completely separating the anterior from the posterior regions of the body, and occupies about a half whorl. This condition is not found in the archaeogastropods and is regarded as apomorphic.

94. Centra) pad a broad fold: 0= long; 1= short (Bittium varium, Finella dubia, A laba incer-ta) (Cl- 100, RJ- 100).

In the ventral gastric surface of cerithioideans there is a central pad. This structure surrounds the duet to the digestive gland and it is situated between this duet and the gastric shield. The central pad is found in 2 main forms: 1) flap-like, relatively thin and free {Modulus, Turńtella, Serpulorbis and Campanile), and 2) a broad large fold, greatly attached to gastric surface (other species). In this last case, the central pad may become very complex, with several folds, someof them with differentiated acina, as in some pleurocerids (Binder, 1959, fig. 8 of Potadoma, Starmiihlner, 1969; this study) and in Faunus (Houbrick, 199lb, fig. 24).

95.    Crescentic ridge: 0= absent; 1= part of central

pad {Aylacostoma spp., pleurocerids, Bittium varium, Finella dubia, A laba incerta, Cerithidea costata)-, 2= isolated firom central pad {Melanoides tuberculatus, Cerithium atratum) (CI= 50, RI= 81, additive).

96.    Crescentic ridge form: 0= ridge-like; 1= broad

{Bittium varium, Finella dubia, A laba incerta) (CI-100, RI-100).

The crescentic ridge is another structure found on the ventral inner surface of the stornach; this ridge generally surrounds the posterior region of the central pad and may, or may not, fuse with it some point. The crescentic ridge is broad and almost of the same size than cenhal pad in miniatur! forms {Bittium, Finella and A laba) and in Diastom melanoides (Houbrick, 198 lc, fig. 5G).

97. Ducts to digestive gland: 0= two; 1= single (all taxa except Campanile symbolicum ani Serpulorbis decussatus) (Cl= 33, RI= 66). Most cerithioideans have a single duet to the digestive gland, in contrast with double ducti