Dizoniopsis sp.

Pimenta, Alexandre Dias, Faria, Raquel Garofalo De Souza, Figueira, Raquel Medeiros Andrade & Fernandes, Maurício Romulo, 2024, Unraveling another of the ‘ Big Fiveʹ: new species and records of Cerithiopsidae from Brazil (Caenogastropoda: Triphoroidea), Zootaxa 5494 (1), pp. 1-71 : 54-56

Dizoniopsis sp.

( Fig. 29 )

Material examined. Brazil: -- Rio de Janeiro state: HAB 13 sta. H4: MNRJ 16267 [3*p].

Characterization. Shell subcylindrical, elongated, narrow, with 3.0 mm long, 0.8 mm wide, ratio length/width 3.7. Protoconch subcylindrical, whitish, 430 µm long, 275 µm wide, 4.5 whorls; embryonic shell dome-shaped, smooth; larval shell with a thin spiral cord, situated at 15% of whorl length above the suture, vanishing in last protoconch whorl; minute granules between suture and spiral cord. Teleoconch with up to seven weakly convex whorls; color beige, interspaces between nodules on spiral cords slightly darker; two spiral cords, the abapical one more prominent in initial whorls, the adapical one more prominent in late whorls; 18 slightly prosocline axial ribs on the body whorl; rounded to elliptical, medium-sized nodules (occupying 43% of body whorl length); suture wide, with a thin sutural cord; smooth subperipheral cord; one thin, smooth basal cord, close to the subperipheral cord.

Remarks. Dizoniopsis includes species with various sculptures of protoconch and teleoconch ( Jay & Drivas 2002; Landau et al. 2018), which having two spiral cords throughout most (or all) teleoconch whorls. For example, the type species Dizoniopsis bilineata ( Hörnes, 1848) has the abapical spiral cord of teleoconch splitting into two cords on the body whorl ( Landau et al. 2018: pl. 62, fig. 2a), whereas Dizoniopsis concatenata ( Conti, 1864) has the adapical cord splitting into two cords on the body whorl ( Bouchet et al. 2010). Most species currently allocated to Dizoniopsis show a distinct spiral or axial sculpture in the protoconch, whether multispiral or paucispiral; they probably represent different phylogenetic lineages (e.g., Jay & Drivas 2002; Bouchet et al. 2010; Landau et al. 2018).

Dizoniopsis sp. from Brazil resembles the Mediterranean species Dizoniopsis zannii Cecalupo & Perugia, 2018 . They share an elongated shell shape and a mainly smooth multispiral protoconch, with a thin spiral cord immediately above the suture on some whorls of the protoconch. However, D. zannii shows minute axial marks in the suture zone of the protoconch ( Cecalupo & Perugia 2018), whereas these marks are absent from the single illustrated shell of Dizoniopsis sp. ( Fig. 29 ).

Geographic and bathymetric distribution. Tropical Southwestern Atlantic Province (Rio de Janeiro state), 98 m.

Genus Seila A. Adams, 1861

Type species. Triphoris dextroversus A. Adams & Reeve, 1850 , by original designation.

Figures

FIGURE 29. Dizoniopsis sp. Shell from Rio de Janeiro state (MNRJ 16267). C: protoconch; D: detail of protoconch sculpture; E: body whorl; F: detail of teleoconch whorl. Length of whole shell: A–B: 3.1 mm. Scale bars:A–B: 1 mm; C–D: 100 µm; E–F: 200 µm.