Paradentalium disparile ( d’Orbigny, 1853 )

Simone, Luiz Ricardo L., 2009, Comparative morphology among representatives of main taxa of Scaphopoda and basal protobranch Bivalvia (Mollusca), Papéis Avulsos de Zoologia 49 (32), pp. 405-457 : 412-414

Paradentalium disparile ( d’Orbigny, 1853)

( Figs. 10-15 , 65-74 )

Dentalium disparile d’Orbigny, 1853: 202 (pl. 25, figs. 14-17); Scarabino, 1973: 201 (fig. 8); Rios, 1970: 144; Matthews & Rios, 1974: 47; Steiner & Kabat, 2004: 584, 712.

Dentalium (Antalis) disparile : Pilsbry & Sharp, 1897: 56 (pl. 14, figs. 16-21); Henderson, 1920: 47 (pl. 6, figs. 4-8); Maury, 1922: 35; Haas, 1953: 203; Morretes, 1949: 53; Turner, 1955: 311; Penna, 1972: 230; 1974: 111; Abbott, 1974: 385 (fig. 4505); Almeida & Oliveira, 2000: 48, 54 (fig. 2).

Dentalium oerstedii : Jaeckel, 1927: 130 (non Mörch, 1860).

Dentalium (Dentale) disparile : Rios, 1970: 144.

Dentalium (Heteroschimoides) callinthrix : Penna, 1972: 231; Almeida & Oliveira, 2000: 49 (fig. 3) (non Dall, 1889).

Antalis disparile : Scarabino, 1985: 198 (pl. 72, fig. 1012); 1994: 306 (pl. 106, fig. 1500); Díaz & Puyana, 1994: 256 (pl. 71, fig. 1040); García-Valencia & Díaz, 2000: 79; Steiner & Kabat, 2001: 440; 2004: 584.

Dentalium dispareli : Almeida & Oliveira, 2000: 48 (fig. 2) (err.).

Paradentalium disparile : Caetano et al., 2006: 11 (figs. 11-15); 2007: 797 (figs. 4-6); Caetano, 2007: 38-43 (figs. 19-25).

Types: BMNH 1854.10 .4.465, 3 syntypes .

Type locality: Martinique .

Distinctive Description

Shell ( Figs. 10-12 ): Size about 40 mm, walls thick, color white, weakly curved. Relatively abrupt widening (tax of increase about 0.087 mm /mm of length). Sculpture six longitudinal, primary ribs in posterior aperture area; secondary ribs gradually appearing towards anterior, extending up to anterior aperture; inter-rib spaces smooth and somewhat irregular. Posterior pipe normally present. Posterior slit as in preceding species.

Main muscle system ( Figs. 65, 66 ): Very similar in features to those of preceding species, except in being weakly thinner and narrower, and by pallial muscles in anterior region thinner.

Foot ( Figs. 13 , 68, 69 ): Character as described for preceding species, except in being somewhat narrower.

Mantle ( Figs. 65-68 ): General features similar to those of preceding species. Main differences following. Anterior edge thick, feebly thicker than shell wall, length of thickness equivalent to 5% of total shell length; unclear separation in pair of edge folds. Pallial gland ( Fig. 67 : pl) a narrow transverse band located at short distance from, and weakly narrower than mantle anterior edge. Posterior mantle flap with narrower slit ( Fig. 66 ).

Pallial cavity ( Figs. 67, 68 ): Characters as described for preceding species. About 7-8 transverse folds also present in basal level of foot ( Fig. 67 : pf). Glandular area located just posterior to folds absent, presenting another located closer to mantle edge ( Fig. 67 : pl).

Visceral mass ( Figs. 67, 68 ): Characters similar to those of preceding species, except in being somewhat narrower and with stomach proportionally shorter. Cruciform-like musculature of integument in postero-ventral region of foot absent.

Circulatory and excretory systems ( Fig. 67 ): Pericardium and kidney with similar characters of previous species.

Digestive system ( Fig. 68 ): Characters similar to F. carduus , except for the following features: Quantity of captacula apparently smaller ( Fig. 13 ) but with similar remaining attributes; Oral tube edge straight; Odontophore muscles ( Figs. 69-72 ): mj, pair of thin protractor muscles, slightly thicker; m3, shorter, about half of odontophore width ( Fig. 71 ); m7, pair narrower and placed along median line ( Fig. 69 ). Odontophore cartilages (oc) somewhat rectangular (with rounded vertices), about twice long as tall. Radula ( Figs. 14, 15 ) with about 15 rows of radular teeth along its length. Radular teeth: rachidian (central) tooth with slightly more rounded cutting edge. Esophagus with glandular inner surface. Pair of lateral tooth with more irregular distal-medial tip, barely forming hooks. Stomach with about 1/9 of total shell length; marginal digestive diverticles in lateral edges; about 15 pairs of similar-sized diverticles. Intestine performing a complex set of loops as shown in Fig. 68 .

Genital system: Characters somewhat similar to those of preceding species, except for more elongated and narrower gonad fashion ( Fig. 67 ).

Central nervous system ( Figs. 68 ): Main characters similar to those of Coccodentalium carduus , with the following remarkable features: Pair of cerebral ganglia more elongated laterally, possessing a single anterior nerve each ( Fig. 74 ); Pair of pedal ganglia located in ventral surface of dorsal wall of foot base ( Fig. 73 ); Each statocyst with volume approximately 1/3 of each pedal ganglion; Pair of buccal ganglia located more laterally in ventral wall connecting odontophore to esophagus ( Figs. 70 : bg); distance between both buccal ganglia equivalent to 3/4 of odontophore width.

Measurements (respectively antero-posterior length, dorso-ventral maximal lateral inflation in mm; finally tax of increase in mm/mm of length): MZUSP 25589: #1: 34.1 by 3.0, 0.088; #2: 30.6 by 2.8, 0.092.

Distribution: Florida, USA to Santa Catarina, Brazil.

Habitat: Sandy bottoms, from intertidal to 103 m depth, living species from 5 to 50 m depth. Content of buccal tube several foranmifer testa.

Material examined: BRAZIL. Rio de Janeiro. Angra dos Reis (iii/1969) , MZUSP 25586 , 19 specimens (sta. 345) , MZUSP 25589 , 2 specimens (sta. 334) , MZUSP 25590 , 1 specimen (sta. 341); Ilha Grande (R.V. Emilia) , MZUSP 18135 , 1 specimen (sta. 38, 12/xii/1965) , 13 m depth, MZUSP 18137 , 2 specimens (sta. 46, 10/xii/1965) , MZUSP 25573 , 1 specimen (sta. 30, 13/xii/1965) . São Paulo. Ubatuba (Seção Bentos col.), Boqueirão, MZUSP 25645 , 62 specimens (9/v/1962) , Praia Sul, 16 m depth, MZUSP 25639 , 2 specimens (23/ii/1962) , Enseada do Flamengo , MZUSP 25627 , 4 specimens (17/i/1962) .

Family Gadilidae

Genus Polyschides Pilsbry & Sharp, 1898 (Type: Siphodentalium tetraschistum Watson, 1879 , OD)

Figures

FIGURES 1‑15: Shell, radular and anatomical aspects of Dentaliidae: 1-9) Coccodentalium caduum; 1) Shell, whole right view, MZUSP 32977, length = 74.0 mm; 2) Detail of anterior aperture, profile, right view; 3) Detail of sculpture of middle region. 4) Anterior aperture, anterior view, animal still inside; 5) detail of posterior aperture, dorsal view, scale = 2 mm; 6) Radula in situ, anterior view, scale = 1 mm; 7) Radula removed from odontophore, ventral view, scale = 1 mm; 8-9) Radulae of 2 specimens in SEM, scale = 200 µm; 10-15) Paradentalium disparile; 10) Shell, whole left view, MZUSP 25589#1, length = 35.1 mm. 11) Same, detail of posterior aperture; 12) Shell, whole left view, MZUSP 25589#2, length = 31.5 mm; 13) Detail of dissected anterior region, central view, captacula deflected to show foot, scale = 2 mm. 14-15) Radulae of 2 specimens in SEM, scales = 100 µm.

FIGURES 65‑74: Paradentalium disparile anatomy: 65) Whole right view; 66) Detail of posterior region, dorsal view; 67) Whole ventral view, mantle opened longitudinally along median line and deflected; 68) Anterior region, mainly showing digestive tubes, right view, foregut opened longitudinally, topology of some adjacent structures also shown, trajectory of intestine indicated in indicated schematic representation at left, a transverse section of esophagus in indicated level also shown; 69) Odontophore, ventral view; 70) Same, dorsal view; 71) Odontophore, posterior view, radula completely removed, right m4 deflected; 72) Same, m3 sectioned transversally, both cartilages and left m4 deflected; 73) Pedal ganglia and statocysts, ventral view; 74) Cerebral ganglia, ventral view. Scales = 1 mm.