A new species of Heptageniidae, Paegniodes sapanensissp. nov., is described based on larvae, subimagos, eggs, and COI data. The mayfly genus Paegniodes Eaton, 1881 is reported for the first time from Thailand. The larva of the new species can be distinguished from other known Paegniodes species by i) lamellae of gill I ca 1/4 of fibrilliform portion and ii) mandibles and basal segment of maxillary palp without dense setae on margin. The subimago characters useful to distinguish this new species from previously known species are i) the median stripes on abdominal terga and ii) shape of the female subgenital and subanal plates. The genetic distance between the new species and P. cupulatus (Eaton, 1871) was approximately 11%. The morphological characters of the new species are discussed and compared to other known species.

中文翻译：

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来自泰国的Paegniodes Eaton，1881年（E翅目，Heptageniidae）的第一个记录，带有一个新物种的描述

七节鱼科的一个新种，paegniodes sapanensissp。nov。，是根据幼虫，subimagos，卵和COI数据进行描述的。881蝇属Paegniodes Eaton，1881年首次从泰国报道。新物种的幼虫可以通过以下方式与其他已知的幼虫区分开：i）g的薄片，大约纤维状部分的1/4，ii）上颚的下颚和基节，边缘没有密集的刚毛。可用于区分该新物种与先前已知物种的亚目特征是：i）腹膜上的正中条纹，以及ii）雌性下生殖器和肛门下板的形状。新物种与P. cupulatus（伊顿，1871）之间的遗传距离约为11％。讨论了新物种的形态特征，并将其与其他已知物种进行了比较。