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odontophore, in which several muscles have inverted arrangement. This fact is shown, for example, by site of mll-m7 complex, tumed towards posterior, while normally they are tumed towards anten or.

Characters Description and Discussion

The organization of the following section is based on papers of other recent phylogenetic analyses (e.g., Pinna, 1996). The account on each character begins with an abbreviated descriptive sentence followed by plesiomorphic and derived condition (s); also followed by CI and R1 (consistency and retention indices, respectively), values for the character under the most parsimonious hypothesis. The indices are shared with the outgroups. A list of terminal taxa exhibiting the apomorphic condition is presented after each derived State, following the order presented in the descriptions.

The outgroup choice was done in following terms: hypothesizing the Cerithioidea as the “stem group” of the Caenogastropoda (Haszprunar, 1988), the choice of a non-caenogastropod prosobranch group was regarded as better for present analysis, rather than other caenogastropod taxon. Other caenogastropods, however, were used in the cases in which homologies of structures in archaeogastropods were uncertain or not possible.

The following non-caenogastropods are included in present analysis as outgroups: 1) Patellogastropoda: Propilidium curumim Leal & Simone (1998); 2) Cocculiniformia: Addisonia enodis Simone, 1996a, Copulabyssia sp. (person, obs.); 3) Vetigastropoda: flaliotis aurantium Simone, 1997, //. poutalesii Dali, 1881, //. tuberculata Linne, 1758, //. lamellosa Lamarck, 1822 (Simone, 1997); Pleurotrochus atlanłicus Rios & Matthews, 1968 (MZSP 23824, 18387); Calliostoma depictum Dali, 1927 (MZSP 28322); 4) Neritimorpha: Helicina sp (MZSP 28673), Neritina zebra (Bruguiere, 1792) (MZSP 28204). However, it is impracticable to include all these species in the table, being reunited in the single collective term “archaeogastopods”. However, the tenn “Archaeogastropoda” denotes a paraphyletic taxon, only utilized in present discussion without taxonomic sense. A similar approach is provided by Sasaki (1998) in a phylogenetic analysis of the basal gastropods, in such some data are also extracted.

Several species belonging to other caenogastropod taxa were also examined (e.g., Simone, 1995a, 1995b, 1995c, 1996b), and sometimes are included in discussion. However, in the table only the following species are mentioned: 1) Viviparidae: Viviparus acerosus (Bourguignat, 1862) (person, obs.) 2) Littorinidae: Littorina Jlava (King & Broderip) (Simone, 1998) and 3) Hydrobiidae: Polhamolithus ribeirensis (Pilsbry) (Simone & Moracchioli, 1994).

The term “basal” caenogastropods means those groups which łąck canal in shell aperture and generally precede the Cerithioidea in most catalo-gues, e.g. Abbott (1974), Rios (1994). In particu-lar those examined species of Littorinidae and Hydrobiidae.

Shell

1.    Form: 0= globose; 1 = turriform (all taxa except

M. modulus and vermetids); 2= uncoiled {Serpulorbis decussatus) (CI= 66, Ri= 75, not additive).

The globose shell shape appears to be the rule among the vetigastropods and nerithimorphs, as well as in basal caenogastropods (littorinids, hydrobioids). This type of shell shape is found in the cerithioideans only in Modulidae, and thus regarded as plesiomorphic. Other cerithioideans present an elongated-tumform shell shape, some of them very long, as Turritella, while others not so long, as Planaxidae. The elongated shell shape is almost absent in archaeogastropods, and present in few other caenogastropod taxa (some ctenoglossans and terebrids), thus, it is here considered apomorphic.

2.    Differentiated siphonal canal: 0= absent; 1=

present (Supplanaxis nucleus, Doryssa macapa, M. modulus, Batillaria minima, Campanile symbolicum) (CI= 20, Rl= 0).

3.    Anterior notch in aperture: 0= absent; 1 = present

(All taxa except Turritella hookeri and Serpulorbis decussatus) (Cl= 50, RI= 83).

Most of cerithioideans present, in different