Collection records and distributional updates of six rarely collected North American large river mayfly taxa (Insecta: Ephemeroptera)

Sampling the Lower Mississippi River (LMR) main channel and secondary channels during 2014–2015 and subsequent dietary analysis of river sturgeons (<i>Scaphirhynchus</i> spp.) captured in the Missouri River resulted in the collection of larvae of six mayfly species that specialise in large river habitats. Some of these mayflies are found in large numbers when encountered, while others are infrequently collected and always in low numbers. Two species, <i>Raptoheptagenia cruentata</i> (Walsh, 1863) and <i>Cercobrachys</i> sp. cf. <i>serpentis</i> Soldán, 1986 (Insecta: Ephemeroptera) are reported for Mississippi for the first time. <i>Pseudiron centralis</i> McDunnough, 1931 and <i>R. cruentata</i> are reported for Arkansas for the first time. Updated North American distributions are presented and include records available in major collections and published literature. The apparent restriction of these taxa to large river environments highlights the need for implementation of conservation and restoration efforts to ensure their persistence.

2014—2015年，研究团队对下密西西比河（Lower Mississippi River, LMR）主河道与支流开展采样工作，并对在密苏里河捕获的铲鲟属（<i>Scaphirhynchus</i> spp.）鱼类开展后续食性分析，期间采集到6种特化于大型河流生境的蜉蝣（mayfly）幼虫。部分蜉蝣类群在被发现时可形成大规模种群，其余类群则罕有采集记录，且单次采集的个体数量始终偏少。本次研究首次在密西西比州报道了<i>Raptoheptagenia cruentata</i>（Walsh, 1863）与<i>Cercobrachys</i> sp. cf. <i>serpentis</i> Soldán, 1986（昆虫纲：蜉蝣目（Ephemeroptera））两个物种。此外，<i>Pseudiron centralis</i> McDunnough, 1931与<i>R. cruentata</i>亦为首次在阿肯色州被报道。本研究整合了主要馆藏标本记录与已发表文献中的相关数据，更新了上述类群在北美大陆的分布范围。这些类群明显仅局限于大型河流生境，这凸显了开展针对性保护与修复工作以保障其种群存续的必要性。