Gadila braziliensis ( Henderson, 1920 )

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 : 417-418

Gadila braziliensis ( Henderson, 1920)

( Figs. 23-29 , 87-94 )

Cadulus (Platyschides) braziliensis Henderson, 1920: 124 (pl. 19, fig. 16); Turner, 1955: 316; Scarabino, 1970: 41 (pl. 1, fig. 1); 1973, 198-199 (fig. 6); 1975: 182 (pl. 58, fig. 887); 1985: 201 (pl. 73, fig. 1032); 1994: 309 (pl. 107, fig. 1520); Penna-Neme, 1974: 115; Steiner & Kabat, 2004: 570, 715.

Cadulus (Platyschides) brasiliensis : Rios, 1966: 7; 1970: 143; 1975: 182 (pl. 58, fig. 887) (err).

Platyschides braziliensis : Scarabino, 1980: 113 (pl. 1, fig. 9).

Gadilabraziliensis: Steiner&Kabat,2001: 445;2004: 570; Caetano, 2007: 150-153 (figs. 141-142).

Cadulus braziliensis : Absalão et al., 2005: 175-178 (fig. 2); 2006: 67.

Type: holotype and paratype USNM 96113 .

Type locality: BRAZIL, off Rio de Janeiro, 23°08’S 41°34’W, 108 m depth (USBF) .

Distinctive Description

Shell ( Figs. 23-25, 29 ): Size about 8 mm, walls thin, color white-translucent, regularly curved; outer surface smooth, glossy. Relatively abrupt widening (tax of increase about 0.133 mm /mm of length). Wider portion weak, located approximately in anterior 1/5 of shell. Weakly dorso-ventrally compressed. Anterior aperture oblique, elliptical. Posterior aperture about half of anterior aperture, circular. Other details in above given references.

Main muscle system ( Fig. 88 ): Components similar to those described for Polyschides noronhensis .

Foot ( Figs. 87, 88 ): Mostly similar in features to that of preceding species. Tip clearly rounded, stubby.

Mantle ( Figs. 87, 88 ): General features as described for Polyschides noronhensis .

Pallial cavity ( Fig. 87 ): Characters similar to those described for Polyschides noronhensis , except in lacking transverse folds in posterior level of foot-visceral mass, pallial gland, and transverse fold located close to mantle edge.

Visceral mass ( Figs. 88 ): Similar organization of preceding species.

Digestive system ( Figs. 88-92 ): Mostly similar to Polyschides noronhensis characters, distinctive features following: Odontophore muscles ( Figs. 28 , 89-92 ): mj, inconspicuous; m4, pair slightly narrower ( Figs. 90, 91 ); m6, narrower 1/8 of each odontophore cartilages thickness ( Figs. 28 , 91, 92 ). Odontophore cartilages (oc) with ventral edge with wide furrow in middle level ( Fig. 92 ). Radular teeth ( Figs. 26, 27 ): pair of lateral teeth with three sub-terminal cusps in median third, being that more lateral approximately twice larger than remaining ( Fig. 26 ). Intestine slightly broader; performing 3-4 simple loops ( Fig. 88 : in). Anus a relative wide papilla ( Fig. 87 : an).

Genital system ( Figs. 87 ): Features similar to those of preceding species.

Central nervous system ( Figs. 88, 94 , 95 ): Features similar to those described for Polyschides noronhensis . Nerve connected to each cerebral ganglion wider in vicinity of these ganglia, forming almost a ganglion.

Measurements (respectively antero-posterior length, dorso-ventral maximal lateral inflation in mm; finally tax of increase in mm/mm of length): MZUSP 46736: #1: 7.8 by 1.3, 0.166; #2: 7.4 by 1.1, 0.149.

Distribution: Rio de Janeiro, Brazil, to La Plata river, Argentina.

Habitat: Sandy bottoms, from 23 to 220 m depth. Content of buccal tube several foranmifer testa.

Material examined: Types. BRAZIL (R.V.W. Besnard). Rio de Janeiro. Angra dos Reis; 23°13’S 44°24’W, 36 m depth, MZUSP 18761 , 2 specimens (R.V.W. Besnard sta. 340, 19/iii/1969). São Paulo. Ubatuba; 23°47’S 44°58’W, 47 m depth, MZUSP 46736 , 11 specimens (P.I. sta. 4854, 17/xii/1985) .

Class Bivalvia

Family Nuculidae

Genus Ennucula Iredale, 1931 (Type: Nucula obliqua Lamarck, 1819 , OD)

Figures

FIGURES 16‑29: Shell and radular aspects of Gadilidae: 16-22) Polyschides noronhensis; 16) Holotype shell, left view, length = 8.6 mm; 17) same, paratype MZUSP 32011, length = 7.8 mm; 18) Paratype MZUSP 32011#1, left view, detail of anterior aperture in profile with some captacula, scale = 0.5 mm; 19-20) Paratype MZUSP 46736, detail of posterior aperture in profile, right and left views respectively, scale = 0.25 mm; 21-22) Radulae of 2 specimens in SEM, scale = 50 µm; 23-29) Gadila braziliensis MZUSP 46736; 23) #3, right view, length = 7.5 mm; 24) #2, dorsal view, length = 7.9 mm; 25) #4, young specimen, length = 3.4 mm; 26) Radula in SEM, scale = 50 µm; 27) Same in light microscopy; 28) Odontophore, radular ribbon removed, ventral view, maximum diameter = 0.7 mm; 29) #2, left view, detail of posterior aperture in profile, scale = 0.5 mm.

FIGURES 87‑94: Gadila brasiliensis anatomy: 87) Whole ventral view, anterior half of pallial cavity opened longitudinally along median line; 88) Foot and haemocoel, right view, more superficial structures, mantle and integument extracted, a portion of left retractor muscle of foot extracted to show intestine; 89) Odontophore, ventral view, superficial layer of membranes removed; 90) Same, posterior view; 91) Odontophore, radular ribbon removed, ventral view; 92) Same, both cartilages deflected, m3 transversally sectioned, right m4 deflected; 93) Central nervous system, left view, topology of adjacent esophagus also shown; 94) Same, anterior view. Scales = 0.5 mm.

FIGURES 95‑100: Ennucula puelcha anatomy: 95) Whole right view, right valve and part of mantle right lobe removed; 96) Mantle edge, transverse section in middle portion of its ventral region; 97) Gill, transverse section in its middle region along 5 filaments; 98) Posterior half of visceral mass, dorsal-slightly right view, right mantle lobe and dorsal portion of pericardium removed; 99) Digestive tubes, main musculature and central nervous system in situ, right view, semi-diagrammatic representation artificially transparent; 100) Region of posterior adductor muscle, right-slightly posterior view, pallial lobes fully removed. Scales = 1 mm.