Streptaxis contusus (Férussac, 1821)

Streptaxis contusus (Férussac, 1821) View in CoL

( Figures 4–5 View Figure 4 View Figure 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 View Figure 4 View Figure 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 View Figure 5 (E)).

One juvenile (MNRJ 22783; Figure 4 View 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 View 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 View 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).