We describe, for the first time, egg masses and larval developmental mode of a recently described Antarctic philinoid snail, Waegelea antarctica. Egg masses resembled the gelatinous, attached masses of many temperate philinoid species and contained very large offspring that hatched as developmentally advanced veligers with many juvenile features. Like other Antarctic heterobranch egg masses, development in the masses of W. antarctica appeared to be largely synchronous despite low internal oxygen levels. Hatched larvae could both swim and crawl, and we did not observe metamorphosis over several days. Molecular barcoding using cytochrome c oxidase subunit I (COI) showed an almost perfect (<0.002% difference) match between our specimens from McMurdo Sound in the Ross Sea and a single sequence from a specimen collected >8,000 km away in the Weddell Sea, suggesting either high realized larval dispersal or a recent range expansion. We also describe the egg mass of the related Antarctophiline alata (identified using COI barcoding) from the Ross Sea, which differed from published descriptions in having considerably smaller embryos.

中文翻译：

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南极头蜗牛 Waegelea antarctica (Cephalaspidea: Antarctophilinidae) 的卵块和幼虫发育，以及相关 Antarctophiline alata 的卵块的注释

我们首次描述了最近描述的南极 philinoid 蜗牛 Waegelea antarctica 的卵块和幼虫发育模式。卵块类似于许多温带类植物的凝胶状附着块，并包含非常大的后代，这些后代孵化为发育先进的具有许多幼体特征的绒毛虫。与其他南极异枝卵块一样，尽管内部氧含量低，W. antarctica 块的发育似乎在很大程度上是同步的。孵化的幼虫既能游泳又能爬行，几天来我们没有观察到变态。使用细胞色素 c 氧化酶亚基 I (COI) 的分子条形码显示，我们在罗斯海的麦克默多海峡的标本与来自收集的标本的单个序列之间几乎完美匹配（<0.002% 差异）>8，000 公里外的威德尔海，这表明要么是高度实现的幼虫扩散，要么是最近的范围扩大。我们还描述了来自罗斯海的相关 Antarctophiline alata（使用 COI 条形码识别）的卵块，这与已发表的描述不同，其胚胎相当小。