Helicina inaequistriata Pilsbry, 1900

Helicina inaequistriata Pilsbry, 1900 View in CoL

( Figures 2 (A–E), 12(A–C))

Records in PNM da Cidade sta. 5, 5 May 2022 [2 spm, MNRJ 22770 View Materials ]; sta. 4, 19 May 2022 [1 spm, MNRJ 22781 View Materials ]; sta. 18, 22 December 2022 [1 spm] ; sta. 2, 5, 15, 2 July 2024 [4 spm, MNRJ 61774 View Materials ] .

Description of radula (MNRJ 22781)

Formula n-4-1-4-n; central tooth broad, V-shaped, up to 87 µm wide, composed of two nearly rectangular halves, the proximal portion with a slight overlap of one half above the other, the distal portion slightly reflected/folded; lateral teeth L1–L2 irregularly rectangular, with a change of curvature at 30–35% (L1) or 20–30% (L2) of tooth length, from a nearly straight base to the remaining portion pointing towards L4, up to 33 µm (L1) or 35 µm (L2) long, up to 16 µm (L1) or 18 μm (L2) wide at mid-portion; L3 nearly columnar, with a wider base but narrower distal edge (often with a triangular projection below distal edge) than L1–L2, nearly straight or slightly pointing towards L4, up to 27 µm long, 20 µm wide at mid-portion; L1 without cusps on the smooth distal edge, L2–L3 with minute (Continued) cusps (often 5–7) on the serrated distal edge; L4 teeth broad, discoid, up to 29 µm long, 84 µm wide, with a lateral (outer) part comprising 24–38% of tooth width, remaining part with up to 18 small, triangular cusps on the serrated distal edge, with outermost cusps more reduced than median and innermost cusps; marginal teeth much elongated, filiform, up to 92 µm long, with three to four (M1) or four to six (M2 and beyond) small triangular cusps on its distal end; outer marginal teeth with distal portion (and cusps) more reduced and directed downwards compared to inner marginal teeth.

Remarks

This taxonomic identification follows the illustrated lectotype of H. inaequistriata (from Raiz da Serra, Cubatão, São Paulo state) in the website of the Malacology collection of the Academy of Natural Sciences of Drexel University (ANSP), in addition to a topotype imaged by Simone (2006). This is apparently the first description and illustration of the radula of this species. Compared with radulae of other Brazilian species of Helicina ( Colley 2008; Junqueira 2011; Vasconcelos 2015; Simone 2018), the V-shaped morphology of the central tooth of H. inaequistriata is remarkably different ( Figure 12 (B,C)).

Geographic distribution

Brazil: Rio de Janeiro and São Paulo states ( Salvador et al. 2014). In Rio de Janeiro state, the species was previously recorded from Arraial do Cabo ( Salvador et al. 2014) and Duque de Caxias ( Lima et al. 2017); regarding the records from Ilha Grande, these are possibly related to other species ( Vasconcelos 2015). Some specimens from the city of Rio de Janeiro were identified as Helicina angulata Sowerby II, 1842 ( Rangel et al. 2021), but the illustrated specimen possibly consists of the same species figured here, requiring further investigation.