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Arquivos de Zoologia

broad sessile base. Ommatophores are present in some outgroups such as vetigastropods and heterobranchs, however of different localization and of apparent independent origin from cephalic tentacles base.

21.    Length: 0= medium (equivalent to snout); 1 =

short (about half of snout length) (Cerithium atratum, Serpulorbis decussatus)', 2= long (about 1.5 times the shout length) {Bittium varium, Finella dubia, Alaba incerta) (Cl= 66, Rl= 66, not additive).

Columellar musde

22.    Length: 0= 1-2 whorls; 1= morę than 3 whorls

(Turritella hookeri, Campanile symbolicum, Serpulorbis decussatus) (Cl= 100, RI= 100).

Mantle edge

23.    Appendices: 0= nonę; 1= scveral papillae

{Turritella hookeri, M. modulus, cerithids, Finella dubia, Batillańa minima, Cerithidea costata, Campanile symbolicum, Serpulorbis decussatus); 2= tentacles (thiarids) (CI= 40, RI= 72, not additive).

Most cerithioideans have the mantle edge entirely covered by smali papillae. There are not similar found among the examined archaeogastropods nor basal caenogastropods, and their presence is regarded as apomorphic. However, some vctigastropods (e.g., Fissurellidae) and patellogastTopods (e.g., Patellidae) present papillae in mantle edge, but normally longer and with complex receptors. A smooth mantle border, although, also occurs among cerithioideans (Pleuroceridae, Alaba, Planaxidae), could be a secondary Ioss. Strongly lobed tentacles on the mantle border are found in the examined thiarids, appearing to be a synapomorphy of the family. However, slender pallial tentacles occur in scaliolids (Ponder, 1994). The uniformity or not of the mantle edge papillae appears to be of secondary iinportance, once both conditions can occur in single species (e.g., Modulus modulus).

No cerithioideans havc a differentiated siphon, the anterior-right region of mantle edge is, at most, thick muscular and undulating, cdging the shell canal.

24.    Anal flap: 0= absent; 1= present (Pachychilus sp.) (Cl= 100, RI= 100).

!

25.    Mantle ventral insertion in head foot: 0= close

to mantle border; 1= far ffom mantle border (Turritella hookeri, Cerithidea costata, Campanile symbolicum, Serpulorbis decussatus) (Cl= 50, Rl= 66).

The insertion of the mantle in the head-foot in the columellar muscle ventral surface, is very posterior in some species and appears to be associated with taxa that need to protrude greatly from the shell, without moving it, such as vermetids and turritellids. However this character was also found in Campanile and Cerithidea.

26.    Mantle eye: 0= absent; 1= present {Cerithidea

costata) {Cl= 100, RI= 100).

In the case of cerithideids, in the region of the siphon there is a well-developed, apomorphic eye, which includes a lens (Houbrick, 1986a, 1988). The cerithid Gourmia gourmyi (Crosse) has about 7 pallial eyes in the incurrent siphon, but these are simpler (Houbrick, 198Ib).

Osphradium

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27.    Type: 0= ridge-like and smooth; 1= ridge-like

and pectinate (cerithids, Finella dubia, Alaba incerta); 2= elliptical and pectinate {Campanilesymbolicum) (CI= 100, RI= 100, not additive).    J

28.    When ridge-like: 0= smooth; 1= bipectinate

{Cerithium atratum); 2= monopectinate {Bittium varium, Finella dubia, Alaba incerta); ?= inapplicable (elliptical osphradium) (C. symbolicum) (CI= 100, Rl= 100, j additive).    ?

The typical cerithioidean osphradium is the ; ridge-like type with a smooth, homogeneous ! surface; this is shared also with other ;

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caenogastropods such as littorinids and hydrobioids (Taylor & Miller, 1989; person, obs.). But the osphradium is pectinate in two cerithioidean . groups. In the first group the osphradium has smali ’ bipectinate leaflets, but has maintained its long, . ridge-like shape, e.g., Cerithium atratum (this . paper); C. nodulosum Bruguićre (cf. Houbrick, 1992a: 127, figs 92B-C), Rhinoclavis aspera