Cyclothone braueri (Stomiiformes, Gonostomatidae) is a widely distributed fish inhabiting the mesopelagic zone of marine tropical and temperate waters. Constituting one of the largest biomasses of the ocean, C. braueri is a key element in most of the ecological processes occurring in the twilight layer. We focused on the ecological processes linked to early life stages in relation to marine pelagic environmental drivers (temperature, salinity, food availability and geostrophic currents) considering different regions of the Central Mediterranean Sea. A multivariate morphometric analysis was carried out using six parameters with the aim of discerning different larval morphotypes, while a fragment of 367 bp representing the 12S ribosomal RNA gene was used to perform molecular analyses aimed at determining the intraspecific genetic variability. Analysis highlighted two geographically distinct morphotypes not genetically discernible and related to the different nutritional conditions due to spatial heterogeneities in terms of temperature and food availability. The body depth (BD) emerged as an appropriate morphometric parameter to detect the larval condition in this species. Molecular analysis highlighted a moderate genetic divergence in the fish population, showing the recurrence of two phylogroups not geographically separated.

Cyclothone braueri (Stomiiformes, Gonostomatidae) 是一种广泛分布的鱼类，栖息于海洋热带和温带水域的中层海域。构成海洋中最大的生物质之一，C. braueri是发生在暮光层的大多数生态过程中的关键元素。考虑到地中海中部的不同区域，我们专注于与海洋远洋环境驱动因素（温度、盐度、食物供应和地转洋流）相关的早期生命阶段的生态过程。使用六个参数进行多变量形态计量分析，目的是辨别不同的幼虫形态类型，同时使用代表 12S 核糖体 RNA 基因的 367 bp 片段进行分子分析，旨在确定种内遗传变异性。分析强调了两种地理上不同的形态类型，它们在遗传上无法辨别，并且由于温度和食物供应方面的空间异质性而与不同的营养条件有关。体深 (BD) 成为检测该物种幼虫状况的合适形态测量参数。分子分析强调了鱼类种群中的适度遗传差异，显示了两个在地理上没有分离的系统群的复发。