Mayfly Species Research Articles

Genetic insights, assessment of ecological niche and projected distribution changes of the mountain mayfly species Andesiops peruvianus under climate change in the andes

Genetic insights, assessment of ecological niche and projected distribution changes of the mountain mayfly species Andesiops peruvianus under climate change in the andes

New Late Cretaceous (Cenomanian) fossil mayfly nymphs (Oligoneuriidae, Heptageniidae, Hexagenitidae) from the Redmond Formation, Labrador, Canada

Three new fossil mayfly (Ephemeroptera) larvae from the Redmond Formation (Cenomanian) of Newfoundland and Labrador, Canada, are described: Alatuscapillus icarus gen. et sp. nov. (family Oligoneuriidae), Cruscolli sheppardae gen. et sp. nov. (family Heptageniidae), and Protoligoneuria borealis sp. nov. (family Hexagenitidae). This discovery marks the first juvenile insect nymphs to be described from this formation and helps fill gaps in our understanding of the global and temporal distribution of mayflies during the Cretaceous period. Of these, C. sheppardae marks the oldest occurrence of the family Heptageniidae in the fossil record, while A. icarus and P. borealis mark the first fossil occurrences of the families Oligoneuriidae and Hexagenitidae in North America. The anatomy, preservation, and behaviour of these new mayfly species inferred from modern taxa consolidate the hypothesis that the Redmond Formation’s palaeoenvironment was lacustrine in nature.

Checklist of mayflies (Insecta: Ephemeroptera) of Luxembourg.

For this study, 11,399 records of mayfly species (Insecta: Ephemeroptera) have been accessed since 1990 for Luxembourg. The compiled checklist includes 52 species, however, three species have not been observed for more than 70 years: Prosopistoma pennigerum (Müller, 1785), Ephoron virgo (Olivier, 1791) and Isonychia ignota (Walker, 1853). Particularly noteworthy are the first record of Arthroplea congener Bengtsson, 1908 as well as the re-finding of Caenis macrura (Stephens, 1836).

Detailed DNA barcoding of mayflies in a small European country proved how far we are from having comprehensive barcode reference libraries.

Mayflies (Ephemeroptera) are among the crucial water and habitat quality bioindicators. However, despite their intensive long-term use in various studies, more reliable mayfly DNA barcode data have been produced in a negligible number of countries, and only ~40% of European species had been barcoded with less than 50% of families covered. Despite being carried out in a small area, our study presents the second-most species-rich DNA reference library of mayflies from Europe and the first comprehensive view from an important biodiversity hotspot such as the Western Carpathians. Within 1153 sequences, 76 morphologically determined species were recorded and added to the Barcode of Life Data System (BOLD) database. All obtained sequences were assigned to 97 BINs, 11 of which were unique and three represented species never barcoded before. Sequences of 16 species with high intraspecific variability were divided into 40 BINs, confirming the presence of cryptic lineages. Due to the low interspecific divergence and the non-existing barcoding gap, sequences of six species were assigned to three shared BINs. Delimitation analyses resulted in 79 and 107 putative species respectively. Bayesian and maximum-likelihood phylogenies confirmed the monophyly of almost all species and complexes of cryptic taxa and proved that DNA barcoding distinguishes almost all studied mayfly species. We have shown that it is still sufficient to thoroughly investigate the fauna of a small but geographically important area to enrich global databases greatly. In particular, the insights gained here transcend the local context and may have broader implications for advancing barcoding efforts.

Freshwater macroinvertebrates along the Nigeria-Cameroon border enhance the conservation value of the lower Guinea forest biodiversity hotspot

In Nigeria and tropical Africa, the bias towards the protection of natural sites on account of terrestrial biodiversity or their resultant ecosystem services has led to a considerably low number of freshwater conservation studies in the region. To close this gap, six lotic freshwater systems in three different natural sites (Obudu Mountains, Agbokim Waterfalls, and Cross River National Park) along the Cameroon border of Nigeria were evaluated for the biodiversity of macroinvertebrates and some aspects of water quality in December 2021 and March 2022. Among other macroinvertebrate-related indices, the community conservation index (CCI), which considers the presence of threatened, rare, and notable species, was used for the conservation evaluation of the freshwater systems. The Ephemeroptera-Plecoptera-Trichoptera (EPT) species were notably rich at the sites, with over 12 species each at the Afundu Stream, Kwa River, Cataract Stream, and Agbokim River. All of the sites had a very high conservation value, according to the CCI, which was greater than 20. Some Obudu sites (Grotto and Becheve streams), despite having fewer EPT taxa, had higher CCI than the Kwa or Agbokim River. This was due to the presence of the endangered damselflies (Africocypha centripunctata and Allocnemis vicki) at the Obudu sites and a rare mayfly species in Nigeria (Tricorythus tinctus), which was reported at Agbokim and Kwa Rivers. The presence of a notable damselfly genus (Pentaphlebia) at the Afundu stream of the Obudu Mountains also raises some hope that the critically endangered damselfly (Pentaphlebia gamblesi), whose adult was last seen in 1973, could still be alive at the site. Canonical Correspondence Analysis revealed that the proportion of scrapers had a strong association with high BOD and EC in Agbokim River, while the Becheve and Grotto streams which had high vegetal cover was positively associated with shredders. Also, increasing DO in Afundu Stream, Kwa River and Cataract Stream was positively associated with EPT richness. This study revealed that more freshwater ecological studies need to be conducted at isolated natural sites and protected areas in Africa. Findings from such studies have implications for preserving freshwater ecosystems of high conservation value from the various threats that characterize the Anthropocene.

The imaginal morphology of the species Kangella brocha (Kang and Yang, 1995) from southern China (Ephemeroptera: Ephemerellidae)

Kangella brocha (Kang & Yang, 1995), a mayfly species known on nymphs only, has been previously placed in three different genera. Here, their first-found adults and additional nymphs from southern China reveal some new characteristics. Apart from its elongated mouthparts, extended outer incisors, widened prothorax, and shortened caudal filaments in the nymph stage, the adult exhibits a robust thorax, straight forceps, and large penes with dorsal projections. These distinct features, observed in both immature and alate stages, provide compelling evidence that this species deserves an independent genus. Therefore, the genus Kangella Sartori, 2004 is reinstated, and this species is reclassified under it. Functionally, the outstanding outer incisor likely serves purposes such as digging or capturing prey. Our finding not only narrows the distribution gap between two populations of this species but also enriches the diversity of ephemerellids in terms of ecological adaptations.

Baetidae (Insecta: Ephemeroptera) of Aurès Mountains (Algeria): A New Species of the Baetis alpinus Species Group, with Notes on Baetis Laech, 1815 Biogeography within Maghreb.

A new species, Baetis (Baetis) dihyaesp. nov., belonging to the Baetis alpinus species group, is described and illustrated based on larval material collected in the Aurès Mountains (northeastern Algeria) in 2020-2021. This new species is closely related to three European species, e.g., Baetis (B.) alpinus (Pictet, 1843); B. (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 by the combination of the following characteristics: (i) more than one short, stout bristle at the tip of segment II of the maxillary palp and (ii) a well-developed paracercus. However, the new species clearly differs from all congeners of the Baetis alpinus species group primarily by the (a) structure of mouthparts-with 14-18 long submarginal setae arranged in a single irregular row on the dorsal surface of the labrum; 2-6 short, stout bristles at the tip of segment II of the maxillary palp; and segment II of the labial palp without a considerably developed apico-internal lobe); (b) setation of abdominal terga, with a few triangular-shaped scales sparsely scattered near the posterior margin only; and (c) a well-developed paracercus, comprised of more than 50 segments. Primary data on the biology and distribution of this new species are provided, and molecular affinities are verified by the analysis of COI (barcode) sequences. Detailed notes on the distribution of mayfly species belonging to the Baetis alpinus species group common in Western Europe and the western part of North Africa are presented. The historical movement of Baetis representatives between Europe, North West Africa, and subsequently Algeria, with the land bridges 'Strait of Gibraltar' and 'Strait of Sicily' as colonization routes, is discussed in detail and identified in the present study as the Western Algeria colonization path and Eastern Algeria colonization path, respectively.

Chronic toxicity testing including transcriptomics-based molecular profiling in Cloeon dipterum

The so-called EPT taxa have been shown to be highly sensitive to various environmental pollutants. However, there are only few published studies on toxicity testing with EPT representatives and there is a particular lack of protocols for chronic toxicity testing, e.g., for integration into species sensitivity distribution (SSD) approaches. To address this gap, we performed a long-term 38-day semi-static toxicity test with the European mayfly species Cloeon dipterum using the insecticide fipronil as model substance. The functionality of the test system was confirmed by the high emergence rate of 85% in the control condition. We found a high sensitivity with regard to larval development with an EC50 of 180 ng/L and a NOEC of 38.0 ng/L after 7 days exposure. After 38 days, an LC50 value of 185 ng/L and an EC50 value of 160 ng/L for emergence (both: NOEC = 38.0 ng/L) were calculated. In a short-term 7-day toxicity test, we found a similar effect on larval development. In addition to the physiological endpoints, we examined fipronil-induced gene expression changes at the transcriptome level in this test. Our results revealed a concentration-dependent increase in the number of differentially expressed genes, as well as observed effects on larval development. Notably, we identified marker gene candidates involved in nervous system development, mirroring the known mode-of-action of fipronil in C. dipterum. The affected genes primarily play crucial roles in neurological processes. Concluding, within this two-step approach we were able to identify fipronil effects on the sublethal physiological endpoint larval development and to complement these effects at the molecular level by gene expression changes in the transcriptome. Thus, this assay proved to be suitable to assess sublethal effects as well as the mode-of-action of substances in the non-standard organism C. dipterum already after a short-term exposure of 7 days. However, further testing is required to validate the procedure.

Checklist, distribution, diversity, and rarity of mayflies (Ephemeroptera) in Slovakia.

Despite the essential role of mayflies (Ephemeroptera) in freshwater ecosystems and their long-term use in research and routine biomonitoring in the Carpathian and Pannonian ecoregions, their distribution data are fragmentary and outdated. All published and unpublished data on mayflies from Slovakia was gathered and a database of > 15,000 species records from 2206 localities built with the aims (i) to critically revise available data and assess the completeness of the species inventory, (ii) to identify hotspots of species diversity, and (iii) to provide a benchmark for assessment of species rarity and conservation status in the region. After the critical revision of the data covering more than 100 years, the occurrence of 109 mayfly species in Slovakia was confirmed. The species inventory appears to be nearly complete, as evidenced by the rarefaction curve and a nonparametric species richness estimator. The highest mayfly gamma diversity was recorded below 500 m a.s.l. and in streams of the fifth order, which can be considered hotspots of mayfly diversity in the region. Six species were last recorded before 1990 and thus can be considered extinct in Slovakia. Twenty-nine species could be classified as very rare, with their occurrence frequency decreasing with increasing altitude and most of them being restricted to large lowland rivers and stagnant water habitats in their floodplains. In conclusion, our study provides comprehensive data on key freshwater bioindicators and suggests increasing conservation priorities, especially in lowland river floodplains occupied by several very rare mayfly species.

Factors structuring patterns of Ephemeroptera (mayflies) species assemblages in different segments of the Western Ghats of peninsular India—a snapshot

Species assemblage patterns of the mayflies (Ephemeroptera) in different segments of the Western Ghats (WG) of peninsular India including those on “sky islands” are presented. An updated checklist of species of WG mayflies is provided and sorted by traits of individual species and supplemented by personal observations. Comparisons are made in this context with patterns of current distribution of some ancient lineages of myriapods, amphibians and birds from the WG focusing on relative roles of geographical barriers (gaps), paleoclimatic, eco-evolutionary scenarios and anthropogenic impacts. This is to highlight the need to prioritize conservation of this rapidly shrinking precious biological heritage. Future work on molecular aspects of intra- and interspecific diversity of mayflies, which are “sentinels of inland water ecosystem health” should be augmented in tune with current research trends in montane “sky islands” especially from adjacent Oriental tropics.

Relationships between reference site quality and baetid mayfly assemblages in mountainous streams of the Luvuvhu catchment, South Africa

With water quality deteriorating rapidly at a global scale, river sections suited to serve as reference sites are being increasingly lost. It thus becomes critical to develop rapid methods to confirm that previously monitored sites continue meet the requirements of reliable reference sites. In the absence of pristine sites, 9 near-natural sites, as defined by the Kleynhans (1996) classification, were used as reference sites for the Luvuvhu River catchment to compare the quality of physico-chemical factors against a biological metric. Baetid mayfly community structure at a site was chosen as an index of water quality, since this family is common in all types of freshwaters, highly diverse and adapted to unpolluted running water. Baetid larvae were sampled monthly from stones-in-current biotopes across 9 sites for over 1 year, between December 2016 and January 2018. A Spearman’s correlation test was used to evaluate the relationship between physico-chemical factors and identify redundant variables. Water quality standards were measured against the national water quality guidelines for aquatic ecosystems. We used a generalized linear model to determine the effect of physico-chemical variables on baetid species, and canonical correspondence analysis to show the relationships between baetid species, sites, and physico-chemical variables. A total of 3 039 individuals belonging to 12 mayfly species were recorded. Our findings indicated that while the physico-chemical factors were highly variable, they were within favourable ranges to reflect reference site conditions. While water temperature was the most important driver of baetid community structure in general, as it negatively affected their abundances, a subset of species (Pseudoponnota sp., Pseudocloeon sp., Acanthiops varius and Demoulinia crassi) showed clear responses to changes in TDS and stream width. We conclude that specific baetid species show good potential as biological indicators of reference sites and chronic water temperature stress, making assessment of reference sites easier.

Mayfly Larvae (Ephemeroptera) in Thailand: Diversity and Science Communication

Mayflies (Ephemeroptera) are one of the most common components of aquatic assemblages in freshwater environments and contribute to ecosystem services. Mayflies have been widely used as indicators of water quality and frequently play an important role in biomonitoring protocols. Mayflies exhibit a decrease in taxa richness with increases in stream or river pollution and degradation. A series of taxonomic studies on Thai mayflies reported 19 families, 73 genera, and approximately 176 species. The families Baetidae and Heptageniidae are the most diverse and widespread groups of Thai mayflies. Our understanding of the diversity of Thai mayflies has steadily increased in recent years. New genera are being described: Cymbalcloeon Suttinun, Gattolliat & Boonsoong, 2020; Elatosara Malzacher, 2020; Megabranchiella Phlai-ngam & Tungpairojwong, 2022; Mekongellina Malzacher, 2019; Sangpradubina Boonsoong & Sartori, 2016; and Thainis Malzacher, 2020. New species and new country records are constantly being discovered in Thailand. Nevertheless, the number of genera and species seems to be lower than the species diversity estimation, and several genera and species remain undescribed. Research on the systematics and ecology of mayflies has been increasing in recent years. DNA barcoding can provide a powerful supplement to the traditional morphological approach to species delimitation. The book entitled “Mayfly Larvae in Thailand” (Thai version) and the boardgame “Thai Mayflies” were developed for environmental science communication. Further efforts are required to assess the conservation status of mayfly species. Thus, data on mayfly diversity and ecological requirements could be used as tools to evaluate environmental impacts on water resources and to drive future research on biodiversity conservation management strategies.

Water temperature and the growth of Ameletus inopinatus (Ephemeroptera: Ameletidae) in the Cairngorms, Scotland

Ameletus inopinatus Eaton, 1887 is the only arctic-alpine mayfly species found in the British Isles. Previous research in Europe using climate models has shown that the geographical range of this species is likely to contract as water temperatures increase. As such, A.inopinatus is particularly vulnerable to the impacts of climate warming. The impact of water temperature on the development of A.inopinatus larvae was investigated in the Cairngorms National Park in Scotland. We closely linked larval development to water temperature with snow cover playing an important role in ensuring emergence occurs before watercourses cease to flow in early summer. The results of this study confirm the vulnerability of A. inopinatus to rising water temperatures and provide new information to help target mitigation measures to prevent further losses of this species.

MATERIALS ON THE FAUNA OF EPHEMEROPTERA, PLECOPTERA AND TRICHOPTERA OF THE KRONOTSKY NATURE RESERVE AND OTHER REGIONS OF KAMCHATKA

As a result of collection in 2014–2021, additional information was obtained on the fauna and distribution of three orders of amphibiotic insects Ephemeroptera, Plecoptera and Trichoptera of the Kronotsky State Natural Biosphere Reserve and other regions of the Kamchatka Peninsula. The general list of the three orders the studied territory includes 56 species: 8 species of mayfl ies, 17 – stonefl ies, and 31 – caddisfl ies. For the territory of Kronotsky Nature Reserve are noted 50 species: 8 – mayfl ies, 11 – stonefl ies, and 31 – caddisfl ies; the presence of 48 previously known species is confi rmed. Stonefl y Capnia nigra (Pictet, 1833) and caddisfl y Hydropsyche kozhantschikovi are fi rst fi nds for the reserve. Plecopterans Plumiperla diversa (Frison, 1935) is discovered for Geyser Valley streams for the fi rst time, and Isocapnia orientalis Zhiltzova, 1975 is a new fi nding for the Kamchatka Peninsula.

The effect of preservation on biomass and length estimates and its variation within and between two mayfly species

Biomass estimation offers insight into aquatic ecosystem processes and represents a powerful tool for measuring biomass in communities. However, the accuracy of this estimate depends considerably on the sample preservation method and biological traits of species. We quantified the effect of commonly used preservatives (70% ethanol, 4% formaldehyde, freezing), preservation time and initial body length on the estimation bias of body length, wet mass and dry mass in two mayfly species with dorsoventrally flattened (Rhithrogena carpatoalpina) and cylindrically elongated (Habroleptoides confusa) bodies. Freezing caused the largest relative bias in the length estimates (up to 18%). Both ethanol and freezing led to significant underestimation of wet mass of preserved animals (up to 26%). The most severe biases were observed in dry weights, where all preservation methods reduced body mass by up to 89%. Importantly, initial body mass influenced the bias caused by preservation, and the larger animals were less affected by mass losses. In contrast, larger individuals were subject to greater length reduction. Additionally, the length–mass relationship for R. carpatoalpina, based on fresh mass of living animals, was significantly different from relationships based on preserved animals. Overall, formaldehyde caused the least biased estimates of length and biomass in both examined species. This case study indicates that direct measurements of unpreserved individuals or length–mass equations based on fresh material are likely the best ways to avoid severe underestimation of biomass in aquatic insects. However, more studies covering a broader range of taxa are needed to reach general conclusions.

Linking levels of trace-metal concentrations and ambient toxicity to cladocerans to levels of effects on macroinvertebrate communities

Ecological impacts of chemicals such as metal mixtures in the field are predicted by one of two approaches: component-based and whole-mixture approaches. Knowledge about how to relate results of these approaches to field effect levels is limited. We aimed to examine the ability of two methods to discriminate field effect levels: (1) a component-based approach that calculates a cumulative criterion unit (CCU) equal to the sum of the ratios of four trace-metal concentrations (Cd, Cu, Zn, and Pb) to the corresponding US EPA hardness-adjusted water quality criterion, and (2) a whole-mixture approach that employs three ambient toxicity levels based on acute and chronic toxicity tests with cladocerans. To assess field effect levels, we used data from benthic macroinvertebrate surveys conducted at 26 sites, including 13 metal-contaminated sites, in four river basins across Japan. Based on decreases in mayfly richness and abundances of two metal-sensitive mayfly families, we defined four field effect levels 0–3: (0) no significant effect; (1) a significant decrease in ephemerellid and/or heptageniid mayfly abundance; (2) a significant decrease in mayfly richness; and (3) no mayflies or a few baetid mayfly species present. Sites with CCU values of ∼5–10 were assigned to either field effect level 1 or 2, while a site with a CCU value of 27 was assigned to field effect level 3. Sites with significant chronic toxicity to cladocerans (ambient toxicity level 1) were assigned to field effect level 1 or 2, whereas those with significant acute and chronic toxicity (ambient toxicity level 2) were assigned to field effect level 2 or 3. CCU values and ambient toxicity levels were both significantly correlated with field effect levels. These results provide encouraging evidence that field effect levels such as losses of species richness can be approximately discriminated by CCU values and ambient toxicity levels.

Physiological and life history responses in a mayfly (Callibaetis floridanus) inhabiting ponds with saltwater intrusion

Freshwater salinity varies in natural systems and plays a role in species distribution. Anthropogenic alterations to freshwater salinity regimes include sea level rise and subsequent intrusion of saline waters to inland habitats. While mayflies are generalized to be sensitive to increasing salinity, we still know remarkably little about the physiological processes (and their plasticity) that determine the performance of species in a changing world. Here, we explored life-history outcomes and physiological plasticity in a population of Callibaetis floridanus (Ephemeroptera: Baetidae) from a coastal pond that routinely experiences saltwater intrusion. We reared naiads from egg hatch to adulthood across a gradient of increasing salinities (113, 5,020, 9,921 μS/cm). Radiotracer flux studies (22Na, 35SO4, and 45Ca) were conducted in naiads reared at each salinity, revealing a positive association between ionic concentration and uptake rates. However, the influence of rearing history on ionic influx rates was apparent when naiads were transferred from their respective rearing water to the other experimental conditions. For example, we observed that naiads reared in the low salinity treatment (113 μS/cm) had 10.8-fold higher Na uptake rates than naiads reared at 9,921 μS/cm and transferred to 113 μS/cm. Additionally, naiads acclimated to the higher salinity water exhibited reduced uptake in ion-rich water relative to those reared in more dilute conditions (e.g., in 9,921 μS/cm water, 113 and 5,020 μS/cm acclimated naiads had 1.5- and 1.1-fold higher Na uptake rates than 9,921 μS/cm acclimated naiads, respectively). We found no significant changes in survival (80 ± 4.4%, mean ± s.e.m.) or naiad development time (24 ± 0.3 days, mean ± s.e.m.) across these treatments but did observe a 27% decrease in subimago female body weight in the most dilute condition. This reduction in female weight was associated with higher oxygen consumption rates in naiads relative to the other rearing conditions. Collectively, these data suggests that saline adapted C. floridanus may be more energetically challenged in dilute conditions, which differs from previous observations in other mayfly species.

Are Intermittent Rivers in the Karst Mediterranean Region of the Balkans Suitable as Mayfly Habitats?

Intermittent rivers, common in dry parts of the world, such as the Mediterranean region, are hydrologically harsh habitats characterized by periodical flow cessation. Ephemeroptera are aquatic insects common in both lotic and lentic waterbodies, where they show a high sensitivity to anthropogenic modifications of their habitat. Therefore, they are widely used as bio-indicators of the freshwater’s health. However, mayfly assemblages and their ecological requirements in the karst Mediterranean intermittent habitats are still not sufficiently known. Thus, the work presented here includes an analysis of mayfly assemblages and their relationship with environmental variables in the lotic phase of four intermittent rivers in the karst Mediterranean region of Croatia. Considering that the studied intermittent rivers are hydrologically extreme environments, a total of 12 recorded mayfly species could be considered as rather high species richness. Nevertheless, species richness per river was quite low (between three and six), and was highly influenced by river morphology, physico-chemical water properties (especially conductivity, water velocity, and concentrations of dissolved oxygen), and anthropogenic pressures. Our results could contribute to the mayfly species protection in karst Mediterranean intermittent freshwater habitats in the Balkans, as well as to the development of conservation measures for those threatened habitats.

Mayflies of the Bednja River, Croatia

Here we present the results of a mayfly study conducted on a hydromorphologically altered lowland river in Croatia, the Bednja River. Twenty-two mayfly species were recorded, Baetis fuscatus (Linnaeus, 1761) and Serratella ignita (Poda, 1761) being the most widespread and Paraleptophlebia submarginata (Stephens, 1836) and Cloeon dipterum (Linnaeus, 1761) the rarest species. A significant increase in mayfly species richness was observed along the river course. Nevertheless, cluster analysis showed that their assemblages were not grouped according to the study position along the Bednja River. The lowest species richness and diversity were recorded for the spring area. Surprisingly, the highest species richness was found at a site with moderate hydromorphological alterations, and the highest diversity at a site with severe hydromorphological alterations. This could be because the river is connected to numerous lateral streams and a variety of microhabitats are available. New distribution records in Croatia are presented for some rare species in Croatian freshwater habitats, such as Heptagenia longicauda (Stephens, 1836). Ephemera lineata Eaton, 1870 was recorded for the first time in the Pannonian lowland ecoregion (ER 11) in Croatia. Caenis cf. pseudorivulorum Keffermüller, 1960 has not yet been recorded in Croatian freshwater habitats, but since our identifications are based on juvenile specimens, its occurrence is still to be confirmed.

The Real Characters of Heptagenia ngi Hsu (1936) from China Representing a New Genus (Ephemeroptera: Heptageniidae)

A very common and early named mayfly species from China, Heptagenia ngi Hsu, 1936, has no exact descriptions of its imago nor nymph, so its generic status is not clear. Based on detailed re-descriptions and pictures of all its stages from fresh materials, it is transferred into a new genus Maculogenia Zhou, gen. nov. Its nymph has conspicuous pale-dark colored body, slightly concave posterior margin of head, scattered simple setae on ventral maxillae, spines and very fine hair-like setae on caudal filaments. Similarly, its imago also has remarkable dark stripes and dots on the pale body, small median titillators and short first segment of foretarsi, apically expanded penes without any spines. It is similar to the genera Electrogena, Thamnodontus, and Parafronurus but they can be differentiated easily by above selected key structures.