Search

Ephemera sp. “Burrowing mayflies” Figures 22 (lateral), 23 (dorsal, ventral) Plates 11 (lateral), 12 (dorsal), 13 (ventral) Ephemera sp., a much larger species at approximately 1 cm body length, was scanned at 13.1 µm voxel size, lower resolution than the two baetid specimens at 2.3 µm and 4.1 µm. Smaller abdominal visceral tracheae visible in the baetid scans are likely present in Ephemera but not visible at the scanned resolution. DESCRIPTION: HEAD: Two H-DOc: H-DOc1 extending from H-Ocel, H-DOc2 from H-DCT. H-Ant barely visible in this scan, likely due to lower resolution. THORAX: T 1-VVi originating from H-DCT on left side; T 1-VVi1 from H-DCT and T 1-VVi2 from H-VCT on right side., Published as part of Herhold, Hollister W, Davis, Steven R, Degrey, Samuel P & Grimaldi, David A, 2023, COMPARATIVE ANATOMY OF THE INSECT TRACHEAL SYSTEM PART 1: INTRODUCTION, APTERYGOTES, PALEOPTERA, POLYNEOPTERA, pp. 1-184 in Bulletin of the American Museum of Natural History 459 (1) on pages 1-184, DOI: 10.5531/sd.sp.55, http://zenodo.org/record/7730159

Herhold, Hollister W, Davis, Steven R, Degrey, Samuel P, Grimaldi, David A (2023): COMPARATIVE ANATOMY OF THE INSECT TRACHEAL SYSTEM PART 1: INTRODUCTION, APTERYGOTES, PALEOPTERA, POLYNEOPTERA. Bulletin of the American Museum of Natural History 459 (1): 1-184, DOI: 10.5531/sd.sp.55, URL: http://dx.doi.org/10.5531/sd.sp.55

The mayfly Ephemera (Sinephemera) glaucops Pictet, 1843 has been considered regionally extinct in the Czech Republic, with the last occurrence dating from 1933. Its extinction was connected with the anthropogenic changes of lowland rivers, forming the original habitat of E. glaucops within the area of the Czech Republic. However, the species has been reported as spreading in man-made, often post-industrial waterbodies in Germany, The Netherlands and Austria since the 1970s. We report E. glaucops from the Czech Republic, based on 27 larvae collected in the North Bohemia lignite basin in 2018. All individuals were found at one locality – a small kaolin pit in the shallow part near the shore, mostly without macrophytes. We provide details about the locality and morphological diagnostic characters of E. glaucops. This study highlights the importance of post-industrial sites for aquatic biodiversity as surrogate biotopes for degraded original habitats.

Swarming and mating behaviors of a mayfly species, Ephemera orientalis Mclachlan, 1875 were observed in 2015, 2016, and 2018 at a river bank of the Asahi River, Japan. Males started to make swarms between late April and middle May in 2016 and 2018. The numbers of mated pairs in a swarm correlated with the numbers of flying males in a swarm in 2016 and 2018. Swarms were formed during a limited period at dusk most probably because that interval is free from natural enemies. Males competed with each other to copulate with females in swarms. We clarified the function of the forelegs of males, which are significantly longer than those of females. Males used their forelegs to hold up a female from below. Besides forelegs, males have longer tails than females. We will discuss why sexual differences are found in these traits. Our results represent the first observation of swarm mating behavior in E. orientalis.

A new ichnospecies, Glossifungites gingrasi n. isp., is described from multiple locations in basal sand-filled coastal plain distributary channels of the Turonian (Upper Cretaceous) Ferron Sandstone (central Utah). Glossifungites gingrasi n. isp. is attributed to the ichnogenus Glossifungites based on the presence of scratch imprints, passive fill, and a tongue-shaped structure, yet the new ichnospecies is distinct because it displays transverse bioglyphs that run perpendicular to the planiform structure, which contrasts to the axis parallel bioglyphs present in the ichnospecies G. saxicava. The transverse arrangement of ornamentation exhibited by G. gingrasi n. isp. is observed in modern subaqueous insect burrows produced by mayfly and chironomid larvae, and constitutes a way to differentiate insect-generated burrows from structures produced by crustaceans that are known to create other Glossifungites ichnospecies. Differentiating insect- from crustacean-generated burrows is significant because it provides a way to distinguish bioturbation by marine-recruited fauna from that produced by freshwater fauna in the rock record, making G. gingrasi n. isp. a valuable ichnological tool for paleoenvironmental and stratigraphic interpretation. While G. gingrasi n. isp. may represent a burrow created by a variety of filter-feeding subaqueous insects, the large size of G. gingrasi n. isp. in the Ferron Sandstone suggests that the largest specimens are probable mayfly burrows and supports the assertion that burrowing mayflies (e.g., Polymitarcyidae and Ephemeridae) adapted to domicile filter-feeding during or prior to the Turonian.UUID: http://zoobank.org/a033b22f-bf09-481a-975e-3a1b096154cc

In an effort to evaluate the taxonomic uncertainty of the species status of Hexagenia orlando Traver, 1931 (Ephemeroptera: Ephemeridae), molecular data were used for the first time to test its current classification. Mitochondrial cytochrome c oxidase subunit I (COI) haplotypes were evaluated using three types of analyses in the form of distance-based, tree-based, and model-based delimitation methods. All analyses consistently recovered H. orlando as a valid species. These preliminary results lend evidence reinforcing the current classification scheme and encourage renewed scrutiny of adults and nymphs to hopefully identify additional morphological characters that may serve to separate H. orlando and its congener Hexagenia limbata (Serville, 1829).

Background: Hox genes are key regulators of appendage development in the insect body plan. The body plan of Mayfly (Ephemeroptera) nymphs differs due to the presence of evolutionarily significant abdominal appendages called gills. Despite mayflies’ basal phylogenetic position and novel morphology amongst insects, little is known of their developmental genetics. Here we present an annotated transcriptome for the mayfly Hexagenia limbata, with annotated sequences for putative Hox peptides and embryonic expression profiles for the Hox genes Antp and Ubx/abd-A. Results: Transcriptomic sequencing of early instar H. limbata nymphs yielded a high-quality assembly of 83,795 contigs, of which 22,975 were annotated against Folsomia candida, Nilaparvata lugens, Zootermopsis nevadensis and UniRef90 protein databases. Peptide annotations included eight of the ten canonical Hox genes (lab, pb, Dfd, Scr, Antp, Ubx, abd-A and Abd-B), most of which contained all functional domains and motifs conserved in insects. Expression patterns of Antp and Ubx/abd-A in H. limbata were visualized from early to late embryogenesis, and are also highly conserved with patterns reported for other non-holometabolous insects.Conclusions: We present evidence that both H. limbata Hox peptide sequences and embryonic expression patterns for Antp and Ubx/abd-A are extensively conserved with other insects. These findings suggest mayfly Antp and Ubx/abd-A play similar appendage promoting and repressing roles in the thorax and abdomen, respectively. The identified expression of Ubx and abd-A in early instar nymphs further suggests that mayfly gill development is not subject to Ubx or abd-A repression. Previous studies have shown that insect Ubx and abd-A repress appendages by inhibiting their distal structures, which can permit the development of proximal appendage types. In line with past morphology-based work, we propose that mayfly gills are proximal appendage structures, possibly homologous to the proximal appendage structures of crustaceans.

A key to ephemeropteran nymphs belonging to 8 families, 30 genera and 48 species from the Palni and Cardamom hills of the Western Ghats in Kerala and Tamil Nadu states is presented in this chapter. Sampling was done at 30 sites. Baetidae and Leptophlebiidae diversity was higher compared to Ephemeridae and Ephemerellidae. Mayflies endemic to the Palni and Cardamom hills include Ephemera (Aethephemera) nadinae, Klugephlebia kodai and Indoganodes jobini. This work serves as a taxonomic primer for doing further research on mayfly taxonomy, biology, biogeography and ecology and it will also aid Bio monitoring programs.

Ephemera glaucops F.-J. Pictet, 1843 Fig. 2 Ephemera glaucops F.-J. Pictet, 1843 -1845: 132-134, pl. 8, figs 1-3. Accepted name: Ephemera glaucops F.-J. Pictet, 1843. Locus typicus: “… Genève au bord du lac…”. Type material: MHNG; syntype, ♂ imago; 620 Genthod 48 Genève, coll. Pictet / Gthod, 27.7 [written by F.-J. Pictet, probably giving the place (Genthod) and the date (July 27) of collecting]. – MHNG; syntype, ♂ imago bearing 4 labels (Fig. 2): 620 Genthod 48 Genève, coll. Pictet / Eph[emera] glaucops ♂ imago [F.-J. Pictet’s handwriting] / Gthd 21.7 [Pictet’s handwriting]/ Ephemera glaucops Pictet 1843 M. Sartori det. 1996. – MHNG; syntype, ♀ imago; 620 Genthod 48 Genève, coll. Pictet / G[en]thod, 27.7 [F.-J. Pictet’s handwriting]. – MHNG; syntype, ♀ imago; 620 Genthod 48 Genève, coll. Pictet / G[en]thod, 21.7 [F.-J. Pictet’s handwriting]. Remarks: This is the best series at the MHNG. Besides numerous subsequent misidentifications, there are 4 specimens that still bear a label handwritten by F.-J. Pictet and that were collected at Genthod, near Geneva. Only these 4 specimens can be considered syntypes of E. glaucops., Published as part of Sartori, Michel & Bauernfeind, Ernst, 2020, Mayfly types and additional material (Insecta: Ephemeroptera) examined by F. - J. Pictet and A. - E. Pictet, housed in the Museums of Natural History of Geneva and Vienna, pp. 315-339 in Revue suisse de Zoologie 127 (2) on pages 318-319, DOI: 10.35929/RSZ.0022, http://zenodo.org/record/5743794, {"references":["Pictet F. - J. 1843 - 1845. Histoire naturelle des Insectes Nevropteres. Famille des Ephemerines. J. Kessmann, Geneve, 300 pp. + 47 pl."]}

Hexagenia limbata (Serville in Guerin, 1829) Ephemera limbata Serville in Guérin, 1829: 384, pl. 60, figs 7-9. Palingenia limbata. – F.-J. Pictet, 1843 -1845: 146-148, pl. 12, figs 1-3 (transfer). Hexagenia limbata. – Walsh, 1863: 197 (transfer). Material: NMW; ♂ subimago; Am[erica]. s[eptentrionalis]. Parreyss / Pictet vidit. – NMW; ♀ subimago; 190 Par[reyss]. / Pictet vidit; legs and abdomen missing. – NMW; 1 ♀ subimago; Pictet vidit; fore legs and tip of left fore wing missing. Remarks: F.-J. Pictet (1843: 148) mentioned only two specimens from Vienna, figured on plate XII, fig. 1 (male) and fig. 3 (female). For a detailed discussion of Serville’s material see Ulmer (1921: 233-239). Ludwig Parreyss (1796-1879) was an established dealer in natural history specimens (mostly insects and birds) in Vienna and the MNW acquired very frequently material from him., Published as part of Sartori, Michel & Bauernfeind, Ernst, 2020, Mayfly types and additional material (Insecta: Ephemeroptera) examined by F. - J. Pictet and A. - E. Pictet, housed in the Museums of Natural History of Geneva and Vienna, pp. 315-339 in Revue suisse de Zoologie 127 (2) on page 333, DOI: 10.35929/RSZ.0022, http://zenodo.org/record/5743794, {"references":["Guerin E. 1829 - 1844. Iconographie du regne animal de G. Cuvier: ou, representation d'apres nature de l'une des especes les plus remarquables, et souvent non encore figurees, de chaque genre d'animaux. Avec un texte descriptif mis au courant de la science. J. B. Bailliere, Paris, 217 plates.","Pictet F. - J. 1843 - 1845. Histoire naturelle des Insectes Nevropteres. Famille des Ephemerines. J. Kessmann, Geneve, 300 pp. + 47 pl.","Walsh B. D. 1863. Observations on certain N. A. Neuroptera, by H. Hagen, M. D., of Koenigsberg, Prussia; translated from the original French ms., and published by permission of the author, with notes and descriptions of about twenty new N. A. species of Pseudoneuroptera. Proceedings of the Entomological Society of Philadelphia 2: 167 - 272.","Ulmer G. 1921. Uber einige Ephemeropteren-Typen alterer Autoren. Archiv fur Naturgeschichte (Abteilung A) 87 (6): 229 - 267."]}

Here we revise the entire Ephemeroptera collection of F.-J. Pictet deposited in the Natural History Museum of Geneva (MHNG) and voucher specimens housed in the Natural History Museum of Vienna (NMW). Due to several unforeseen turns of events, the MHNG collection was already in bad condition at the end of the 19th century. However, the specimens sent by V. Kollar to F.-J. Pictet, and used by the latter for his monograph (1843-1845), have been well curated after their return to the NMW and allow an important nomenclatural change. The species Baetis forcipulaF.-J. Pictet, 1843 is now considered a junior subjective synonym of Ephemera venosaFabricius, 1775, currently Ecdyonurus (Ecdyonurus) venosus (Fabricius, 1775). The specimens described by Thomas in 1968b from southwestern France under the name Ecdyonurus forcipula (F.-J. Pictet, 1843) belong to a new species, Ecdyonurus alaini Bauernfeind sp. nov., which is described herein. Mayfly specimens described by F.-J. Pictet's son, A.-E. Pictet, are also reviewed. Furthermore, information is provided on some other valuable specimens housed in the MHNG and NMW, such as Ametropus fragilisAlbarda, 1878 which was already collected in Italy in the 19th century, or Rhithrogena cinctaNavas, 1921 from the Spanish Pyrenees, which is the second specimen currently known of this species.

To better understand how the sulfate (SO42&minus, ) anion may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO42&minus, in four freshwater species: the fathead minnow (Pimephales promelas, Teleostei: Cyprinidae), paper pondshell (Utterbackia imbecillis, Bivalvia: Unionidae), red swamp crayfish (Procambarus clarkii, Crustacea: Cambaridae), and two-lined mayfly (Hexagenia bilineata, Insecta: Ephemeridae). Using &delta, (34S/32S) stable isotope ratios and the concentrations of S and SO42&minus, we measured the SO42&minus, influx rate (Jin), net flux (Jnet), and efflux rate (Jout) during a 24 h exposure period. For all four species, the means of Jin for SO42&minus, were positive, and Jin was significantly greater than 0 at both target SO42&minus, concentrations in the fish and mollusk and at the lower SO42&minus, concentration in the crayfish. The means of Jout and Jnet were much more variable than those for Jin, but several species by target SO42&minus, concentration combinations for Jout and Jnet, were negative, which suggests the net excretion of SO42&minus, by the animals. The results of our experiments suggest a greater regulation of SO42&minus, in freshwater animals than has been previously reported.

The Affon River is one of the important rivers of the Oueme River whose benthic diversity remained unknown. The present study aims to make the relationship between macroinvertebrates and physico-chemical parameters to access water quality of the Affon River. The measurement of physico-chemical parameters (temperature, pH, conductivity, transparency, depth and TDS, dissolved oxygen, ammonium, nitrite and phosphate) and the sampling of macroinvertebrates using a Surber net were carried out during floods in eight stations. A principal component analysis (PCA) and canonical correspondence analysis (CCA) were used. The indices of Shannon, Pielou, Simpson, Hilsenhoff, EPT and EPT/Chironomidae were used to assess the level of water pollution. The study identified 9755 macroinvertebrates divided into 4 classes, 14 orders and 49 families. Pollution-sensitive families (14 families) that are organic pollution indicators, as well as pollution-tolerant families (Chironomidae, Limnaeidae, Bithynidae, Physidae) were captured. Chironomidae were the most predominant and abundant family (FO = 100%). The predominance of Chironomidae coupled with the rarity of the Ephemeroptera, Trichoptera and Plecoptera would reflect the poor quality of the Affon River waters. The principal components analysis yielded groups of associations: The first group of stations Taneka 2 and 3 characterized by high values of ammonium and phosphate; and low values of conductivity and TDS; the second group of Taneka 1 and Kolokonde 1 stations with low values of pH, transparency, ammonium and phosphates; and the third group of stations Kolokonde 2, Kpebouko1, Kpebouko 2 and Affon marked by high values of conductivity, TDS, transparency, depth and temperature. The canonical correspondence analysis revealed a strong positive correlation between Nemouridae and ammonium as well as between Perlidae, Taeniopterygidae, Ephemeridae, Heptageniidae, Isonychiidae, Elmidae and phosphate. This study is a crucial step for any management and monitoring of this river.

Burrowing mayflies (Hexagenia spp.) are important indicators of mesotrophic water conditions, and have been studied for several decades in conjunction with the changing trophic status of western Lake Erie. However, most studies on the biology of burrowing mayflies have failed to differentiate between immature H. limbata and H. rigida, the life stages that are most commonly collected. We developed a simple molecular assay to facilitate species-level identification of the two mayflies as an easier alternative to sequencing the COI gene. We analyzed a total of 152 cytochrome c oxidase, subunit I barcoding sequences from the Barcode of Life Data System (BOLD) for these mayfly species and developed a diagnostic primer set. We tested our primers on 46 random burrowing Lake Erie mayfly nymphs using both conventional PCR and qPCR. Results of the two methods were consistent and unambiguous. Sequencing of the COI barcoding region in the mayflies confirmed that the PCR assays correctly identified mayflies in all cases. Our assay is simple and effective, and will facilitate species-level identification of burrowing mayflies in future studies on their biology where the two species co-occur.

The giant burrowing mayfly, Hexagenia limbata (Serville, 1829) (Figure 1) is one of the most widespread mayflies in North America and is well known for its importance in ecosystem health and water quality monitoring. The mayflies (order Ephemeroptera) are an ancient lineage of aquatic insects originating more than 300 million years ago (Merritt and Cummins 2008). Within this order, the burrowing mayflies of the family Ephemeridae are well-known for their importance in fly fishing and their massive synchronized mating flights.https://edis.ifas.ufl.edu/in1244 Also published on the Featured Creatures website: http://entnemdept.ufl.edu/creatures/AQUATIC/mayfly.html

The potential of mayfly Ephemera orientalis McLachlan eggs and first-instar larvae in ecotoxicological testing was investigated. Both stages of E. orientalis showed high tolerance to various environmental variables, such as water temperature, pH, water hardness, and dissolved organic carbon. Toxicological assays were conducted with three insecticides (emamectin benzoate, endosulfan, and cypermethrin), one fungicide (mancozeb), and one herbicide (paraquat dichloride). The two toxicity endpoints for the assay were the 14-day egg median hatching rate (EHC50) in static and renewal exposure systems and 24-h median larval mortality (LC50). Cypermethrin was the most toxic to both eggs (EHC50 in static system = 36.9 μg/L; EHC50 in renewal system

The considerable literature suggests negative impacts of hydropower on the river. The Alaknanda hydroelectric project was commissioned in the year 2014. Bio-assessment of the river stretch between the dam and power house was conducted using the benthic diatom and macroinvertebrate assemblages. The Van Dam ecologic values and BMWP scores were determined for respective assemblages. The present assemblages were compared with the past data (mid-1990s) in same stretch of the river. Earlier, C. laevis—A. linearis dominated the diatom assemblages, but now A. minutissimum dominated intermittently. Van Dam ecologic values reveal β-mesosaprobic and indifferent to eutraphentic trophic state. Leclercq index depicts degradation and organic pollution. Earlier, Ephemeridae, Simuliidae, Psephenidae, and Chironomidae dominated the benthic macroinvertebrate assemblages, but now Chironomidae prevails. BMWP score shows that water quality has deteriorated from moderately impacted (53–December, 56–April) to unimpacted state (120–March) in past and heavily (7–10) to moderately impacted state (41–54) at present.

We examined whether or not sizes of eggs and offspring were related to emergence date or maternal size in a semelparous aquatic insect (the burrowing mayfly, Hexagenia) in which parental care is lacking and oviposited eggs are passively dispersed. We quantified the size of males and female imagos over the emergence span at a site on the Detroit River, Canada, and investigated relationships between emergence date and female size and (1) egg size and (2) size of first-instar nymphs. Although size of female imagos (H. limbata and H. rigida combined) declined significantly (P

Eatonigenia zhangi sp. nov. Eatonigenia chaperi Zhang, 1988: 68 (male, female, subimago) (nec. Hexagenia chaperi Nav��s, 1935: 99, misidentification); Zhang et al., 1995: 74; She et al., 1995: 80; You and Gui, 1995: 91. Diagnosis. The new species can be distinguished from the other species of the genus based on the following characteristics: in males, larger and more colorful body, slightly projected apex of penis and three tips of gonopores; in nymphs, larger and paler body, smaller fore-claw and asymmetrical labrum. Nymph (in alcohol, not mature, Figs. 1, 3 A): Body length 20.0 mm, cerci 4.0���6.0 mm, terminal filament 3.0 mm. Body ivory pale, with golden setae on most parts of body. Head (Figs. 1, 3 A, 5A): Length of frontal processes slightly shorter than width, its anterior margin smoothly convex and narrower than posterior margin; all free margins with dense golden setae; base of antenna projected forwards with relatively long setae on supra-antennal surface; scape of antenna slightly longer than pedicel, the latter with setae on basal half; flagella with sparse setae; length of antenna subequal to head width; compound eyes dark, surrounded with a row of setae; upper half of ocelli pale, lower half dark; area between 3 ocelli slightly pigmented grey; vertex pale (Fig. 5 A). Mouthparts: Labrum generally heart-shaped, asymmetrical; free margins and dorsal surface with long anteriorly directed setae (Figs. 2 A, 5F), ventral surface with short mesally directed setae but no long setae (Fig. 5 G). Mandibles asymmetrical, tusk of left mandible shorter than right in dorsal view; triangular mandibular tusks densely setaceous dorsally and laterally with setae progressively shorter toward apex; outer incisor of left mandible much stronger than inner incisor; apex of both incisors of left mandible divided into 3 denticles; prostheca of left mandible modified into a thick spine, with 2 denticles near apex and a small setal tuft next to prostheca (Fig. 2 B); outer incisor of right mandible slightly stronger than inner incisor, apex of both incisors divided into 3 denticles; prostheca represented as 2 spines, one near inner incisor, other close to mola, an additional small setal tuft between them (Fig. 2 C). Maxillae slender, outer margin with relatively long hair distally, inner margin with long spines and hair, apex of galea-lacinia extended to form 2 large spines (canine and dentiseta) (Fig. 2 D), apex of distal spine (canine) bifurcate (Fig. 2 E); maxillary palp 3-segmented although segmentation between second and third segment indistinct; basal and second segment subequal in length, apical segment slightly longer; basal segment with only 2 long setae on outer margin near apex but other segments with long setae over entire surface, those on inner margin longer; cardo with small spine-like setae (Figs.2 D, 5H). Hypopharynx with lingua slightly emarginated to straight on free margin; surface of lingua and superlinguae with setae, setae more abundant on dorsoapical surface and free margin (Fig. 2 F). Labium with dense setae on paraglossae forming brush-like setal tuft; labial palp 2-segmented, apical segment ca. 2�� length of basal segment, basal segment with a thumb-like protuberance, apical segment with fan of long setae and dense spines on surface near apex (Fig. 2 G). Thorax: totally pale to pale grey; pronotum slightly produced laterally, forming a lobe-like structure on anterolateral corners with additional hooked projection and cluster of golden setae, lateral margins with golden setae (Figs. 3 A, 3I, 5A). Length ratio of femur, tibia and tarsus of foreleg 7: 5: 3.6, ratio of midleg 2: 2: 1, hindleg 9.2: 8: 3, midleg shorter than other legs; ventral margin of coxa and trochanter of foreleg with setae, those on trochanter longer and more abundant; forefemur rounded, dorsal surface with 3 longitudinal rows of setae (one median row and rows near margins); foretibia greatly expanded with curved, pointed apex and long setae on margins, sparse and short setae on surfaces (Figs. 3 B, 5C); foretarsus with setae on dorsal surface, apex with cleft, vestigial claw recessed in cleft (Figs. 3 C, 5B); femur and tibia of midleg expanded slightly, tarsi without apical cleft but with slender claw, setal pattern similar to that of foreleg (Figs. 3 D, 5D); all segments of hindleg longer than midleg, coxa with setae on margins and surface, trochanter with very sparse short setae, other segments with longer, and denser setae (Figs. 3 E, 5E); apex of tibia expanded to form large curved projection, its length subequal to tarsus; claw similar to that of midleg but slightly longer and stronger (Fig. 3 F). Abdomen: ivory or pale, with golden hair on lateral margins of terga; gills I forked deeply to one third distance from base (Figs. 3 G, 5I); gills II���VII similar in shape, each of them divided into two lamellae, dorsal lamella broader at base and ventral lamella slender and tapered (Figs. 3 H, 5J); each lamella of gills further divided into large number of fringed filaments; main trachea of gills II���VII clear to pigmented grey to brown; gills VII smaller than anterior pairs; margins of 3 caudal filaments with dense setae, terminal filament shorter than cerci. Male imago (in alcohol, additional characters to those provided by Zhang 1988): Body length 20.0���23.0 mm; forewings 14.0���15.0 mm (Figs. 4 A, 6A), hindwings 6.0���7.0 mm (Figs. 4 B, 6B); body general yellowish brown. Genitalia (Figs. 4 D, 6C): basal segment of forceps broader than distal segments, chestnut pigmented; second segment about 6�� length of basal segment, curved with basal one-third light purplish red; apical segment very small, length slightly longer than broad. Apical two-thirds of fused penes slightly sclerotized and reddish brown. except for pale median groove; posterolateral corners of penes expanded apically forming trapezoidal shape (Figs. 4 C, 6D); basal third of penes membranous; sclerotized projections of gonopores with 3 tips, ventral tip slightly smaller than two dorsal tips (Figs. 4 C, 4D, 6E). Eggs (Figs. 8 A, 8B, dissected from female body): Length 0.2 mm, width 0.1 mm; oval, chorionic surface without distinct structure, surface made up of many polygons; small micropyle with long sperm guide visible on equatorial area. Material examined and collecting information. Holotype: 6, Wan-quan River, near Jia-ji Bridge, Qonghai County, Hainan Province, China, leg. Shu-Sheng SHE and Jun ZHANG, 23-V-1986; Paratypes: 3 66, 5 ♀♀, same as the holotype. Others: 10♀♀ subimagos, 22-V-1986; 10♀♀, 13-V-1986, other information same as types; 1 male subimago, 13-VII-2014, about 2 km downstream Jia-ji Bridge, 13-VII-2014, Jian-Hua DAI, Dan ZHOU and Jun- Zhi SUN; 16 larvae, Qionghai, Wan-quan River (110.465784��E, 19.226526��N), 4 km upstream of Jia-ji Bridge, 6- I-2015, Leg. Chang-Fa ZHOU, Jun-Zhi SUN and Yi-Ke HAN. All specimens are deposited in the Institute of Genetic Resources, College of Life Sciences, Nanjing Normal University, P. R. China. The nymphs described here were collected from fine silt and sand substrates of Wan-quan River, Hainan Island, southern China. The river is wide, averaging at least 80 m in width, and more than 300 m at some sections visited (Fig. 7). It has deep water current in all seasons. Other mayflies collected at the same habitat and time include Ephemera and Caenis. This is consistent with the information provided by McCafferty (1973, 1979)., Published as part of Sun, Jun-Zhi, Luo, Juan-Yan & Zhou, Chang-Fa, 2016, The nymph, habitat, and status of Eatonigenia in China (Ephemeroptera: Ephemeridae), pp. 381-389 in Zootaxa 4193 (2) on pages 381-386, DOI: 10.11646/zootaxa.4193.2.12, http://zenodo.org/record/166992, {"references":["Zhang, J. (1988) On the discovery of the genus Eatonigenia (Ephemeroptera: Ephemeridae) in China. Journal of Nanjing Normal University (Natural Science), 3, 68 - 72.","Navas, L. (1935) Decadas de insectos nuevos. Decada 27. Broteria (Ciencias Naturais), 31, 97 - 107.","Zhang, J., Gui, H. & You, D. S. (1995) Studies on the Ephemeridae (Insecta: Ephemeroptera) of China. Journal of Nanjing Normal University (Nature Science), 18 (3), 68 - 76.","She, S. S., Gui, H. & You, D. S. (1995) A research on the mayflies from Hainan Province, China (Insecta: Ephemeroptera). Journal of Nanjing Normal University (Nature Science), 18 (2), 72 - 82.","McCafferty, W. P. (1973) Systematic and zoogeographic aspects of Asiatic Ephemeridae (Ephemeroptera). Oriental Insects, 7 (1), 49 - 67. http: // dx. doi. org / 10.1080 / 00305316.1973.10434204","McCafferty, W. P. & Gillies, M. T. (1979) The African Ephemeridae (Ephemeroptera). Aquatic Insects, 1 (3), 169 - 178. http: // dx. doi. org / 10.1080 / 01650427909360991"]}