Taxonomic Catalog of the Brazilian Fauna: order Trichoptera (Insecta), diversity and distribution

ABSTRACT Caddisflies are a highly diverse group of aquatic insects, particularly in the Neotropical region where there is a high number of endemic taxa. Based on taxonomic contributions published until August 2019, a total of 796 caddisfly species have been recorded from Brazil. Taxonomic data about Brazilian caddisflies are currently open access at the “Catálogo Taxonômico da Fauna do Brasil” website (CTFB), an on-line database with taxonomic information on the animal species occurring in Brazil. The order Trichoptera at CTFB includes a catalog of species recorded for the country, with synonymic lists, distribution throughout six biomes, 12 hydrographic regions, and 27 political states (including Federal District) from Brazil. The database is constantly updated to include newly published data. In this study, we reviewed the taxonomic effort on Brazilian caddisflies based on data currently in CTFB database. The accumulation curve of species described or recorded from the country, by year, shows a strong upward trend in last 25 years, indicating that it is possible that there are many more species to be described. Based on presence/absence of caddisfly species at three geographic levels (biomes, hydrographic regions, and states), second order Jackknife estimated at least 1,586 species occurring in Brazil (with hydrographic regions as unities), indicating we currently know about 50% of the Brazilian caddisfly fauna. Species distribution by Brazilian biomes reveals that the Atlantic Forest is the most diverse, with 490 species (298 endemic), followed by the Amazon Forest, with 255 species (101 endemic). Even though these numbers may be biased because there has been more intense collecting in these two biomes, the percentage of endemic caddisfly species in the Atlantic Forest is remarkable. Considering the distribution throughout hydrographic regions, clustering analyses (UPGMA) based on incidence data reveals two groups: northwestern basins and southeastern. Although these groups have weak bootstrap support and low similarity in species composition, this division of Brazilian caddisfly fauna could be related to Amazon-Atlantic Forest disjunction, with the South American dry diagonal acting as a potential barrier throughout evolutionary time.

摘要：
石蛾（Caddisflies）是一类物种多样性极高的水生昆虫类群，在新热带区（Neotropical region）分布尤为繁盛，该区域拥有数量众多的特有类群。基于2019年8月前已发表的分类学研究成果，巴西境内目前已记录到796种石蛾。当前，巴西石蛾的分类学数据可通过“巴西动物群分类目录（Catálogo Taxonômico da Fauna do Brasil，简称CTFB）”网站公开获取，该在线数据库收录了巴西境内分布动物物种的分类学信息。CTFB中的毛翅目（Trichoptera）类目包含该国已记录物种的完整目录，附带异名列表、以及在巴西6个生物群区、12个水文区域与27个政治行政区（含联邦特区）内的分布数据。该数据库会持续更新以纳入最新发表的研究资料。
本研究基于CTFB数据库中的现有数据，系统梳理了巴西石蛾的分类学研究历程。按年份统计的该国已描述/记录物种累积曲线显示，近25年来呈现强劲的上升趋势，表明尚有大量未被描述的物种有待发现。基于石蛾物种在3个地理层级（生物群区、水文区域、行政区）的存在/缺失数据，以水文区域为统计单元的二阶刀切法（second order Jackknife）估算结果显示，巴西境内至少存在1586种石蛾，意味着当前仅探明了约50%的巴西石蛾类群。
按巴西生物群区统计的物种分布数据显示，大西洋森林（Atlantic Forest）的物种多样性最高，共计490种（其中298种为特有种），其次为亚马孙森林（Amazon Forest），共255种（其中101种为特有种）。尽管这两类生物群区的采样强度更高可能导致统计偏差，但大西洋森林内石蛾特有种的占比仍十分突出。
按水文区域统计的分布数据显示，基于物种出现数据的聚类分析（UPGMA，非加权组平均法）结果可划分为两组：西北流域组与东南流域组。尽管该分组的自举检验（bootstrap）支持率较低且物种组成相似度不高，但巴西石蛾类群的这种分区格局可能与亚马孙-大西洋森林的间断分布相关，而南美干旱对角带（South American dry diagonal）可能在演化过程中充当了潜在的地理阻隔屏障。