Streptaxis contusus (Férussac, 1821)

Streptaxis contusus (Férussac, 1821) View in CoL

( Figures 4–5)

Records in PNM da Cidade sta. 5, 19 February 2022 [1 sh, MNRJ 23804 View Materials ]; sta . 2, 5 April 2022 [1 spm, MNRJ 23835 View Materials ; 1 sh, MNRJ 23831 View Materials ]; sta . 4, 5 April 2022 [1 sh, MNRJ 23837 View Materials ]; sta . 5, 5 May 2022 [2 sh, MNRJ 22773 View Materials , MNRJ 22774 View Materials ]; sta . 6, 14 May 2022 [1 spm, MNRJ 22783 View Materials ]; sta . 6, 19 May 2022 [1 spm, MNRJ 22778 View Materials ]; sta . 5, 10 September 2022 [1 sh, MNRJ 24291 View Materials ]; sta . 6, 22 December 2022 [1 spm, MNRJ 24539 View Materials ]; sta . 2, 17 September 2023 [3 spm]; sta. 5, 17 September 2023 [3 spm, of which 1 sampled, MNRJ 61526 View Materials ]; sta . 2, 2 July 2024 [1 spm, MNRJ 61768 View Materials ] .

Remarks

Because no adult live specimen of S. contusus was found at PNM da Cidade (except empty shells), we sequenced the DNA of four juveniles and one sub-adult ( Figures 4–5) in order to confirm that they represent the same species, despite the considerable change in shell dimensions and the absence of change in shell orientation (only observed in adults – Figure 5 (E)).

One juvenile (MNRJ 22783; Figure 4 (H–J)) was found following the mucus trail of an adult of Thaumastus cf. taunaisii , situated 1 m away. In 17 September 2023, one juvenile of S. contusus at sta. 2 followed the mucus trail of a juvenile of T. cf. taunaisii , but the predation was not confirmed in spite of their proximity (Supplementary material 2), whereas at sta. 5 one juvenile was found above an adult empty shell of T. cf. taunaisii and another juvenile was found eating the remains of Leptinaria unilamellata . One juvenile (MNRJ 24539; Figure 4 (C–E)) was found following the mucus trail of a juvenile of Solaropsis brasiliana , situated 1 m away. When put near the slug Phyllocaulis boraceiensis in the laboratory, the same streptaxid spent several minutes smelling the mucus, but P. boraceiensis was much faster, avoiding predation. The sub-adult ( Figure 5 (C,D)) was found with the head-foot inside a juvenile empty shell of T. cf. taunaisii . Based on literature records, other land snails are also eaten by S. contusus ( Rezende et al. 1962) , including species of Thaumastus ( Krauss 1962; Jurberg et al. 1988).

Geographic distribution: Brazil: Ceará, Pernambuco, Rio de Janeiro, São Paulo and Santa Catarina states ( Barros 1994; Simone 2006; Salvador 2018), including the city of Rio de Janeiro ( Rezende et al. 1962; Alexandre et al. 2017).