Gaza superba ( Dall, 1881 )

Simone, Luiz Ricardo L. & Cunha, Carlo M., 2006, Revision of genera Gaza and Callogaza (Vetigastropoda, Trochidae), with description of a new Brazilian species, Zootaxa 1318 (1), pp. 1-40 : 10-13

Gaza superba ( Dall, 1881)

( Figs. 11–15 , 64–66 , 78–82 )

Synonymy see Clench & Abbott (1943: 2). Complement:

Callogaza superba Dall, 1881: 49 .

Gaza superba: Dall 1889: 354 (pl. 22, figs. 4, 4a). Clench & Abbott 1943: 2 (figs. 1–2, Holotype). Abbott 1974: 49 (fig. 375). Abbott & Dance 1983: 40 (unnumbered text­fig.). Hickman & McLean 1990: 91 (figs. 51b–c, 52, 53b, f, g).

Gaza (Callogaza) superba: Thiele 1929: 78 .

Gaza watsoni: Rios 1985: 20 (pl. 9; fig. 79). 1994: 35 (pl. 10, fig. 104) (non Dall, 1881).

Types: Lectotype MCZ 7541 (not examined) (explicitly designated by Clench & Abbott 1943); Paralectotypes USNM 94992, 6 shells, 3 opercula, 1 dry soft parts (examined).

Type locality: off Montserrat, Caribbean .

Diagnosis: Color of shell pale­beige iridescent; surface smooth, glossy, spire height about 2/3 of body whorl width; about five whorls. Apex open in adult. Body whorl with very low, weak, spiral lines, almost smooth. Height/width ratio 1.52 on average. Carina at lower region of body whorl. Umbilicus about 75% covered by callus. Orifices in anterior part of mesopodium: 12 on left, 8 on right side. Number of epipodial tentacles: 5 on right, 6 on left side. Rachidian tooth with elongated base, about 1/10 of total radular width; about 18 tall, slender marginal teeth.

Distinctive description

Shell ( Figs. 11–15 ): Size, about 40 mm in diameter; color pale­beige iridescent, about five whorls. Protoconch eroded ( Fig. 12 ), forming small whole communicating with umbilicus. Teleoconch with almost glossy surface, iridescent by transparency of external shell layer. Shell surface with weak axial lines, more evident on last whorls. Spire relatively low, height about 2/3 of that of body whorl. Body whorl with weak spiral carina between middle, interior thirds. Umbilicus wide, deep, 75% covered by callus ( Figs. 13, 14 ). Peristome preceded by portion of body whorl weakly projected downwards, amount of deflection equal to 2 spiral lines of sculpture. Outer lip marked by short, thick deflection. Lower half of inner lip with flap­like callus covering about half of umbilicus.

Head­foot ( Figs. 78, 79, 81 ): Distal end of snout somewhat concave, papillated. Papillae at edge 8–10 times longer than those close to mouth, decreasing abruptly in size towards mouth. Cephalic tentacles about twice as long as length of snout. Ommatophores located at outer dorsal base of cephalic tentacles, about 1/10 of tentacles length. Foot’s anterior orifices: 12 orifices on left, 8 on right side ( Fig. 81 : fo). Epipodium with long, slender epipodial tentacles inserted sub­terminally at distal edge, on ventral surface, 5 on right, 6 on left side. Anterior tentacle about 1/4 of foot length, about twice as large as remainder; tip pointed; remaining tentacles similar in size. Posterior end of mesopodium with longitudinal, shallow furrow separating it into two halves.

Operculum ( Fig. 15 ): As in preceding species, except brown color.

Mantle organs ( Figs. 80, 82 ): Gill of about same length as pallial cavity; extended anteriorly by wide, tall suspensory stalk. Anterior end of gill pointed; extended region detached from mantle for about 1/3 of gill length (supported by suspensory stalk). Left gill filaments three times smaller than right filaments, both filaments possessing ventral, pointed projection. Rectum about 1/4 of pallial cavity width, nearly straight ( Fig. 80 : rt).

Digestive system: Foregut, terminal digestive duct parameters similar to those of G. compta . Radula ( Figs. 64–66 ). Rachidian with antero­posteriorly elongated base (about 50% longer than wider), narrowing gradually, about 1/10 of total radular width ( Figs. 64, 65 ); cutting edge with projection turned inwards (almost 90º) covering base of preceding tooth, cutting edge triangular, tip blunt, almost half as wide as base, preceded by narrower, thickened region; cutting edge smooth or with sparse, small pointed cusps. Six lateral teeth with similar features of preceding species; 3–4 small cusps located separated from each other along proximal edge. About 15 tall, slender marginal teeth, of similar shape of those of preceding species; about 18 small, narrow, sharp pointed, well separated cusps on outer side, about 3–4 sub­terminal cusps on inner side.

Measurements of shells (in mm): UFMNH 323758, #1: 32.5 x 21.7; #2: 30.3 x 19.6.

Distribution: Caribbean and Gulf of Mexico.

Habitat: Muddy sand bottom; from 380 to 925 m depth, mostly around 600 m depth, with 1 lot of dead shells at 47 m ( Surinam).

Material examined: Paralectotypes. GULF OF MEXICO. 29º13’N 87º54’W, 380 m , 16 shells, FMNH 57047 (22/vi/1956, H. R. Bullis Jr. leg.), 29º11’N 88º03’W, 417 m , 3 shells, FMNH 66399 (24/ix/1957, H. R. Bullis Jr leg.). UNITED STATES OF AMERICA. Mississippi ( R. V. Oregon, o.t.); South of Pascogoula , 29º09’N 88º12’W, 417–463 m

depth, FMNH 187423 , 6 shells (sta. 3684, 8/viii/1962) , 29º09’N 88º11’W, 472 m depth, FMNH 187436 , 6 shells (sta. 3221, 4/iii/1961) , 29º13’N 87º54’W, 444–454 m depth, 6 shells, FMNH 187425 (sta. 2825, 17/vii/1960) , 1 shell, FMNH 187437 (sta. 3678, 7/viii/ 1962) ; South of Mississippi, Silver Bay , 29º07’N 88º11’W, 555 m depth, FMNH 187430 , 6 shells (sta. 1180, 3/vi/1959) ; Delt Louisiana , 28º16’N 89º02’W, 925 m depth, FMNH 187443 , 2 shells (sta. 1179, 28/viii/1954) ; South of the Mississippi delta, FMNH 69025 , 2 shells (ex. Ted Dranga, 1955). MEXICO. Cape Catoche , 24º22’N 87º47’W, 546 m, FMNH 187429 , 2 shells ( R. V. Oregon, sta. 11134, 9/viii/1970, o.t.). Florida; Florida straits , 24º19.521’N 83º14.953’W, FMNH 323758 , 3 specimens (Sta. GHB­03­05; Bell, T. & Olaivar, B. col. 23/iv/2003) . LESSER ANTILLES ( R. V. Oregon II, o.t.). DOMINICA , 15º39’N, 61º10’W, 657 m depth, FMNH 187422 , 5 shells (sta. 5929, 5/iii/1966) , 15º40’N 61º09’W, 629 m depth, FMNH 187426 , 6 shells (sta. 10827, 1/xii/1969) , 15º42’N 61º18’W, 685 m depth, FMNH 187444 , 1 shell (sta. 10282, 2/xii/1969) ; North of Christopher , 18º28’N 63º23’W, 690 m depth, FMNH 187446 , 5 shells (sta. 10835, 6/xii/ 1969) ; St. Christopher , 17º46’N 62º59’W, 657–676 m depth, FMNH 187432 , 4 shells (sta. 6696, 18/v/1967) , 17º38’N, 62º48’W, 629–703 m depth, FMNH 187448 , 2 shells (sta. 6721) , 17º34’N 63º42’W, 620–707 m depth, FMNH 187441 , 2 shells (sta. 6722, 5/vi/ 1967) . SURINAM. North off Paramaribo, 6º48’N 55º12’W, 47 m depth, FMNH 187447 , 4 shells ( R. V. Oregon, sta. 2284, 8/ix/1958, o.t.) .

Remarks: Rios (1975: 25) reported Callogaza watsoni (under Gaza ) as occurring off Pará, north Brazilian coast, 750 m, on the basis of the material collected by the R.V. Albatross; the illustration provided by the author (pl. 6, fig. 71) was a copy of the original figure by Dall (1889, pl. 22, figs. 7, 7a). In the subsequent editions ( Rios 1985, 1994), the author repeated the record of C. watsoni from Brazil, but illustrating a specimen of Gaza superba ; for this reason, the citations of Rios (1985, 1994) are here transferred to the synonymy of G. superba . However, the reexamination of the material collected by the R.V. Albatross (USNM 97116) revealed that this material actually correspond to C. watsoni (see additional comments in C. watsoni ).

Figures

FIGURES 11–23. Gaza spp. Figs. 11–15: G. superba Paralectotype USNM 94992. Figs. 11–13: Shell in apertural, apical and umbilical views. Fig. 14: Detail of umbilical area. Fig. 15: Operculum, outer view. Scale bar = 10 mm. Figs. 16–19: G. daedala Holotype BMNH. Figs. 16–18: Shell in apertural, apical and umbilical views. Fig. 19: Detail of umbilical area. Scale bar = 5 mm. Figs. 20–23: G. cubana Holotype MCZ 135151. Figs. 20–22: Shell in apertural, apical and umbilical views. Fig. 23: Detail of umbilical area. Scale bar = 5 mm.

FIGURES 58–66. Shell and radulae in SEM. Figs. 58–60: Callogaza watsoni from off Pará, Brazil (specimen mentioned by Dall, 1889, USNM 97116): apertural, umbilical and apical views; diameter = 7.1 mm. Figs. 61–63: Gaza olivacea. Figs. 61–62: Central and lateral teeth. Fig. 63: Detail of lateral teeth; scale bars = 100 µm. Figs. 64–66: Gaza superba. Fig. 64: Entire shell; scale bar= 200 µm. Fig. 65: Detail of central and lateral teeth; scale bar = 100 mµ. Fig. 66: detail of lateral teeth; scale­bar = 100 µm.

FIGURES 78–82. Gaza superba anatomy. Fig. 78: Head­foot, apertural view. Fig. 79: Same, lateral­right view, mantle also shown. Fig. 80: Pallial cavity hoof, ventral view. Fig. 81: Foot, head removed, foot anterior orifices (fo) shown. Fig. 82: Gill, transversal section in its middle region. Scale bars = 2 mm.