New records of marine “ sea slugs ” ( Mollusca : Gastropoda : Heterobranchia ) in the outlets of the estuary systems in Paraná , southern Brazil

Four species of shell-less marine gastropods, collectively called “sea slugs”, are newly recorded from outlets of estuarine systems, the Paranaguá estuarine complex and Guaratuba Bay, on the coast of Paraná state. These include a marine pulmonate slug, Onchidella indolens (Gould, 1852) (Eupulmonata: Systellommatophora: Onchidellidae); two species of sea hares, Bursatella leachii de Blainville, 1817 (Euthyneura: Sacoglossa: Aplysiidae) and Elysia serca Er. Marcus, 1955 (Euthy neura: Sacoglossa: Plakobranchidae); and one species of nudibranch, Spurilla braziliana MacFarland, 1909 (Nudipleura: Aeolidiidae). Egg mass shapes of E. serca and B. leachii are newly described.

Sea slugs are marine gastropods with no shell or the shell reduced and internal.They are hermaphrodites and may have their first stages of life in egg masses attached to a substratum or in larval forms of free living individuals (Schlesinger et. al. 2009;Matthews-Cascon et. al. 2011).Besides, the form and ornamentation of the egg masses are used to identify some heterobranch species (Matthews-Cascon et. al. 2011).
Currently, approximately 200 sea slugs (Cephalaspidea; Systellommatophora; Sacoglossa; Nudibranchia) species are reported from Brazil (Rios 2009;DaCosta et al. 2010).Along the southern coast of Brazil, 45 species were recorded, including 21 from the state of Rio Grande do Sul, 31 from Santa Catarina and 4 from Paraná (Table 1).The perceived paucity of few sea slugs species from Paraná may be associated to the few studies on the group in the area or to a lack of favorable environmental conditions for their development.
In the laboratory, the specimens of the four species were acclimatized in water with salinity varying from 20 to 30 psu.During this period, the specimens of Spurilla braziliana and Elysia serca spawned spiral egg masses (Figure 2).Egg mass shape was previously observed by Matthews-Cascon et al. (2011) for S. neapolitana, but is not previously known for E. serca.Egg masses of Bursatella leachii are a long, coiled, gelatinous string with each egg capsule with more than one larva (Figure 2).In the laboratory, Onchidella indolens and E. serca fed on macroalgae, as also reported by Rios (2009).Spurilla braziliana, preferred to feed on bryozoans and hydrozoans that were attached to oyster shells from which it was collected.
The new record of Elysia serca extends the known range of this species approximately 80 km south of the previous known distribution (Figure 1).The new records of Spurilla bra ziliana and Onchidella indolens in the coast of Paraná fill gaps in the known distributions of these two species, thus enabling a connection between the populations of the States of São Paulo and Santa Catarina, described earlier (Pimpão and Magalhães 2004;Rios 2009;Carmona et al. 2014).Recently

NOTES ON GEOGRAPHIC DISTRIBUTION
increasing knowledge of the reproductive characteristics of heterobranch species in the region.The integration of morphological and molecular tools may also contribute to better identification of species and their distribution, as well as the interaction between populations of heterobranchs in southern Brazil.

ACKNOWLEDGMENTS
Financial support was provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico (Cnpq).Special thanks are due to Hamilton Kirchner and Fazenda Marinha Ostra Viva for the help with equipment in the field work.Carmona et al. (2014) reported that the species of Spurilla present along the Brazilian coast is Spurilla braziliana and not Spurilla neapolitana (Delle Chiaje, 1841).
Heterobranchia from Paraná state are not well known, and this may be due to a lack of appropriate sampling in suitable habitats, both during larval and adult stages.The absence of studies focused in heterobranchs may explain the difference in occurrence of species in the state of Paraná, compared with the larger diversity of sea slugs reported from São Paulo and Santa Catarina.Further fieldwork on the coast of Paraná may add information about species still yet unknown from the state, as well as possibly

Table 1 .
Records of marine heterobranchs from the southern Brazil coast.PR: Paraná state; SC: Santa Catarina state; RS: Rio Grande do Sul state.