Sublittoral and bathyal Harpacticoida (Crustacea: Copepoda) of the Magellan region

Two expeditions, undertaken in 1994 and 1996, provided quantitatively sampled material of sublittoral and bathyal meiobenthos from the Paso Ancho of the Straits of Magellan, the Beagle Channel, and the Patagonian continental slope (Chile). To investigate whether these distinct geographic areas might also be characterised by different harpacticoid assemblages, qualitative and quantitative analyses of Copepoda Harpacticoida were carried out. At supraspecific level 25 harpacticoid families were found, as well as several species that could not yet be assigned to any major harpacticoid taxon. Due to the high amount of collected Harpacticoida, detailed investigations at species level had to be restricted to six taxa, namely the Ancorabolidae, Argestidae, Cletodidae, Diosaccinae, Paramesochridae, and Paranannopinae. The corresponding specimens were assigned to 122 species in 52 genera. More than 80% of them are new to science. Qualitative comparisons of both species composition and species distribution allow the three areas to be distinguished in terms of species richness. However, statistical analyses confirm these results only partly. Similarity analyses applying non-metrical multidimensional scaling, as well as diversity analyses using the rarefaction method, suggest that the observed differences in distribution and diversity patterns are due to small-scale, local conditions, which may overlay possible large-scale ones.

1994年与1996年开展的两次科考航次，获取了智利麦哲伦海峡帕索安乔海域、比格尔海峡及巴塔哥尼亚大陆坡的潮下带与半深海带小型底栖生物（meiobenthos）定量采集样品。为探究这些地理特征迥异的海域是否拥有独特的猛水蚤类群组合，研究人员对猛水蚤目桡足类（Copepoda Harpacticoida）开展了定性与定量分析。在超种分类阶元上，共记录到25个猛水蚤科，同时还发现了若干暂无法归入任一主要猛水蚤分类单元的物种。由于采集到的猛水蚤标本总量极大，物种级别的详细研究仅能聚焦于6个类群，即锚猛水蚤科（Ancorabolidae）、亮角猛水蚤科（Argestidae）、克氏猛水蚤科（Cletodidae）、神足猛水蚤亚科（Diosaccinae）、拟美猛水蚤科（Paramesochridae）以及副南猛水蚤亚科（Paranannopinae）。上述类群的标本共归入52属122种，其中超过80%为科学新物种。通过对物种组成与物种分布的定性比较，可依据物种丰富度对这三个海域进行区分。但统计分析仅部分验证了这一结果。采用非度量多维标度法（non-metrical multidimensional scaling）的相似性分析，以及采用稀疏法（rarefaction method）的多样性分析结果均表明，观测到的分布与多样性模式差异，是由局域小尺度环境条件所导致的——这类小尺度条件可能掩盖了潜在的大尺度格局差异。