Isonychia taishunensis Huang, Shen, Zhang & Cheng sp. nov. is described based on larval samples from Taishun County, Zhejiang Province, China. The new species is distinguished from other species of Isonychia Eaton by the following characters: gill plates with spines apically, the color of abdominal tergum X, color pattern of abdominal terga I–IX, and color pattern of each gill plate. The genetic distance between the new species and other species of Isonychia is over 10% using the Kimura 2-parameter model. The phylogenetic relationship of I. taishunensis is close to the clade of I. japonica Ulmer and I. ussurica Bajkova. The morphological characters and molecular data (COX1, Kimura 2-parameter) support that this new species represents the ninth species of the genus Isonychia in China. The modified key to known larvae of the genus Isonychia is provided.

In this study, the mitochondrial (mt) genomes of Siphluriscus chinensis (Ephemeroptera: Siphluriscidae) were evaluated in specimens collected from two sites in China: Niutou Mountain, Zhejiang Province (S. chinensis NTS) and Leigong Mountain, Guizhou Province (S. chinensis LGS) and were successfully sequenced. The lengths of the mt genomes of S. chinensis NTS and S. chinensis LGS were 15,904 bp (ON729390) and 15,212 bp (ON729391), respectively. However, an in-depth comparison of the two mt genomes showed significant differences between the specimens collected from the two sites. A detailed analysis of the genetic distance between S. chinensis NTS and S. chinensis LGS was undertaken to further achieve an accurate delimitation of S. chinensis. The genetic distance between S. chinensis NTS and the other three species within Siphluriscidae was a high value, above 12.2%. The two mt genomes were used to reconstruct phylogenetic relationships and estimate divergence time. The results demonstrated robust differences between S. chinensis NTS and S. chinensis LGS, which revealed that a kind of cryptic species existed. Maximum likelihood (ML) and Bayesian inference (BI) analyses produced well-supported phylogenetic trees that showed evolutionary relationships between Siphluriscidae (((S. chinensis HQ875717 + S. chinensis MF352165) + S. chinensis LGS) + S. chinensis NTS). The most recent common ancestor (MRCA) of four species within Siphluriscidae began to diversify during the Neogene [11.80 million years ago (Mya); 95% highest posterior densities (HPD) = 6.17–19.28 Mya], and S. chinensis NTS was first to diverge from the branches of S. chinensis LGS. In short, based on mitochondrial genomes, our results showed that the specimens collected from Leigong Mountain, Guizhou Province (S. chinensis LGS) belonged to S. chinensis, and the specimens collected from Niutou Mountain, Zhejiang Province (S. chinensis NTS) were a cryptic species of S. chinensis.

Heptageniidae are known for their flat heads and bodies and are divided into three subfamilies. Despite the extensive diversity within this group and considerable efforts made to understand their evolutionary history, the internal classifications and origin time of Heptageniidae remains controversial. In this study, we newly sequenced 17 complete mitogenomes of Heptageniidae to reconstruct their phylogenetic positions within this family. Because of the ambiguous time of origin, our study also estimated the divergence time within Heptageniidae based on five fossil calibration points. The results of BI and ML trees all highly supported the monophyly of Heptageniidae and three subfamilies. The phylogenetic relationship of Rhithrogeninae + (Ecdyonurinae + Heptageniinae) was also recovered. The divergence time showed that Heptageniidae originated from 164.38 Mya (95% HPD, 150.23–181.53 Mya) in the mid-Jurassic, and Rhithrogeninae originated from 95.54 Mya (95% HPD, 73.86–120.19 Mya) in the mid-Cretaceous. Ecdyonurinae and Heptageniinae began to diverge at 90.08 Mya (95% HPD, 68.81–113.16 Mya) in the middle Cretaceous. After morphological identification, analysis of the mitogenome’s composition, genetic distance calculation, phylogenetic analysis, and divergence time calculation, we suggest that two different populations of Epeorus montanus collected from Aksu, Xinjiang Uygur Autonomous Region (40°16′ N, 80°26′ E) and Xinyuan, Xinjiang Uygur Autonomous Region (43°20′ N, 83°43′ E) in China are cryptic species of E. montanus, but further detailed information on their morphological characteristics is needed to fully identify them.

As one of the four primary evolutionary groups within myriapods, centipedes (Chilopoda) comprise approximately 3150 valid species. Recent molecular studies have begun to elucidate the phylogeny and time to divergence in Chilopoda; yet, identifying scutigeromorphs at the species level remains a notoriously challenging task. In this study, we obtained seven new complete mitogenomes of Thereuopoda clunifera (Wood, 1862) to investigate the phylogeny and divergence times of Chilopoda. Both maximum likelihood (ML) and Bayesian inference (BI) analyses recovered the relationship of (Scutigeromorpha + (Scolopendromorpha + (Lithobiomorpha + Geophilomorpha))). For Scutigeromorpha, seven newly sequenced mitogenomes of T. clunifera were divided into four distinct clades. Divergence time estimates suggest that the basal split of Chilopoda occurred during the Middle Ordovician period, with the origins of Scolopendromorpha, Lithobiomorpha, and Geophilomorpha dating to the Devonian period. Factors such as warm climates, coevolution between predator and prey, and the rifting of the Hainan Island may have driven the diversification of Scutigeromorpha. Based on genetic distance, the delimitation of molecular species, phylogenetic relationships, and divergence time analyses, we identified three cryptic species that existed within T. clunifera. This exceptionally high degree of hidden diversity can be ascribed to the morphological stasis that has occurred since the Paleozoic era and taxonomic impediment.

One new species of bristletail of the genus Silvestrichilis (Microcoryphia: Machilidae), S. shiyanensis Shen, Wang & Zhang, sp. nov. is illustrated and described based on mature adult samples from Wudang Mountain, Shiyan City, Hubei Province, China. The species is named after Shiyan City, the original collection of the type specimens. The following characteristics can be used to distinguish the new species from Silvestrichilis confucius and other congeners: length of the contact line of compound eyes; distribution of setae on articles of the maxillary palpus, labial palpus and legs; length to width ratio for the ultimate article of labial palpus; number of divisions of parameres of male. A key to all Silvestrichilis species in China and the phylogenetic relationship of S. shiyanensis sp. nov. based on COX1 are also presented.

Bristletails (Microcoryphia) represent a relatively understudied group of class Insecta. These wingless hexapods, which retain numerous plesiomorphic structures, remain less well understood compared to most other insect lineages. Through detailed morphological examination of specimens collected from southern China, we describe six new species (Pedetontus (Verhoeffilis) elegans sp. n. from Zhejiang; P. (V.) hezhouensis sp. n., P. (V.) jinxiuensis sp. n., and P. (V.) nanningensis sp. n. from Guangxi; and P. (V.) shenzhenensis sp. n. and P. (V.) xanthospilus sp. n. from Guangdong) of subgenus Verhoeffilis Paclt, 1972. This subgenus is distinguished from other members of the Petrobiinae by several diagnostic features: paired ocelli shoe-shaped (fusiform-shaped) and submedian; two pairs of retractile vesicles on abdominal segments II–V; parameres restricted to coxite IX; penis opening small and apical; male genitalia not exceeding coxite IX; and ovipositor of primary type. The new species can be distinguished from known species and each other by the morphology of the compound eyes, maxilla, labial palps, legs, and genitalia; here, we provide detailed illustrations, tables, and descriptions. Furthermore, we sequence the COX1 gene to construct a phylogenetic tree of Microcoryphia. This contribution increases the total number of reported Pedetontus species in China to seventeen.