Embryonic development of the false limpet Siphonaria lateralis from Atlantic Patagonia

Abstract

Siphonariids are pulmonate gastropods inhabiting rocky intertidal habitats, and many studies have focused on these false limpets around the world. In the southern South Atlantic, studies on reproduction and development in species of Siphonaria are scarce. We studied the embryonic development and egg masses of Siphonaria lateralis at its northernmost distribution in Atlantic Patagonia. In S. lateralis, as in most species of Siphonaria, individuals spawn benthic egg masses that strongly attach to intertidal rocky substrata. A single spherical egg that measures ~120 µm develops inside the egg capsule of S. lateralis. Considering the relatively small egg size, and reports from previous studies, the developmental modality of S. lateralis might be expected to include a planktotrophic larval phase. However, we found that hatchlings emerged as 1‐mm crawling juveniles, probably owing to the presence of intracapsular fluid, which may provide the energetic requirements for direct development. The embryonic size changed little from the egg to veliger stages, and then increased rapidly until the hatchling stage. We compared development in S. lateralis with development in the sympatric Siphonaria lessonii, in which egg size was reported to be ~80 µm and hatching occurs as planktotrophic veliger larvae. In these two species, spawn and early intracapsular developmental modes are remarkably different; these differences represent contrasting ways to survive in the harsh and physically stressful intertidal Patagonian coasts.

Spawn and development of the olivid gastropod Olivancillaria carcellesi from north Patagonia, Argentina

“…However, in waters of the southwestern Atlantic ocean, direct developers are mostly present throughout the more than 5000 km of shallow and deep waters of the Argentine coast (Averbuj et al, 2018;Averbuj & Penchaszadeh, 2016;Gallardo & Penchaszadeh, 2001;Teso & Penchaszadeh, 2019). All these direct development species from Argentine waters showed a diversity of mechanisms for provisioning developing eggs, including nurse eggs (muricids, some calyptraeids, buccinids; Averbuj & Penchaszadeh, 2010;Penchaszadeh et al, 2019;Teso & Penchaszadeh, 2019), intracapsular yolk (naticids, volutids, cephalaspids;Bigatti et al, 2014;Di Luca et al, 2020;Penchaszadeh et al, 2016Penchaszadeh et al, , 2017, and intracapsular albumen or large yolky eggs with or without supplementary sources (cochlespirids, some calyptraeids; Penchaszadeh et al, 2022;Sánchez et al, 2018;Zabala et al, 2020).…”