Despite the fact that the state is one of the smallest in Brazil, representing only 0.53% of the country area, a surprising diversity was found. Seventy-six species, 41 genera and nine families were identified, which represents about 25% of the species reported from Brazil, 65% of the genera, and almost all families. Of these, 17 species (most of Baetidae and Leptophlebiidae) are new to science. Five species, collected only at the nymphal stage, could not be identified to the species level. The present work demonstrates that, as for other organisms, the diversity of mayflies is high in the state, and more works aiming to investigate the aquatic insect composition of the Espírito Santo State should be encouraged.

-Based on collections in three coast Brazilian states, Hydrosmilodon plagatus sp. nov. and Needhamella mazama sp. nov. are described based on nymphs and adults. Besides the description of these species, new geographic records of the Hermanella complex are presented. The species included are: Hermanella maculipennis (Ulmer, 1920); Hermanella froehlichi Ferreira and Domı´nguez (1992); Hydrosmilodon gilliesae Thomas & Pe´ru (2004); Hylister plaummani Domı´nguez and Flowers (1989); Leentvaaria palpalis Demoulin (1966); and Needhamella ehrhadti (Ulmer, 1920). In addition, in this work Leentvaaria palpalis is recorded from Brazil for the first time.

The black fly Simulium (Trichodagmia) hirtipupa Lutz (Diptera: Simuliidae) is widely distributed in southern Brazil, with one report from Amapá state in the northern region of Brazilian Amazonia. Morphological comparison of northern and southern populations revealed differences in all life stages, corroborated by chromosomal and molecular analyses, and indicated that the population previously identified as S. hirtipupa from Amapá state represents an undescribed species. This new species is described based on all life stages above the egg, and its chromosomal and molecular divergence from S. hirtipupa is highlighted. Simulium criniferum n. sp. can be diagnosed by the deeply concave male ventral plate with a prominent median projection bearing a ventral keel; female anal lobe in lateral view with a broadly rounded, distal membranous area about as long as wide; pupa with a boot-shaped cocoon bearing a minutely bubbled surface, cephalic plate and thorax with abundant hair-like tubercles, and gill of 12 translucent filaments with darkly sclerotized, acuminate tips; and larva with the body cuticle bearing spiniform setae, abdomen truncated posteriorly, and gill histoblast in situ with the filament tips directed ventrally. Chromosomally, the new species has five unique fixed inversions and uniquely shares three additional fixed inversions with its nearest relative, S. hirtipupa. Partial COI sequences indicate a genetic distance of ~9% between the new species and S. hirtipupa. Females of the new species are anthropophilic.

-In the present paper, based on the rearing of nymphs in the field, we present for the first time the description of the adult stage of Rivudiva Lugo-Ortiz and McCafferty and of its type species, R. minnatena Lugo-Ortiz and McCafferty. Adults of Rivudiva can be distinguished from the other genera of Baetidae by the following combination of characters: (1) hindwings present or absent, when present with two longitudinal veins and with costal projection pointed, placed in the basal fourth of anterior margin; (2) forceps threesegmented, segment III long, about 2r as long as wide; (3) distal margin of subgenital plate with small pointed projection. Besides that, R. coveloae (Traver, 1971 [Proc. Entomol. Soc. Washington, 73, 58-63]), new combination, and R. venezuelensis (Traver, 1943 [Bol. Entomol. Venezolana, 2, 79-98]), new combination, are proposed based on the characteristics listed above, specially the distal margin of subgenital plate with a small pointed projection. Comments on the biology of the nymphs are also provided.

In the present work, based on material from Brazilian Atlantic Forest, four new species of the Hermanella complex are described. The main characteristics that distinguish the new species from its congeners are, in Hermanella amere sp. nov.: (1) subgenital plate yellow, with wide projection near base of forceps; (2) penis lobe with ventral, robust, posterioly directed spine; in Hermanella nigra sp. nov.: (1 ) subgenital plate brown washed with gray, with wide projection near inner base of forceps; (2) penis lobe with a distomedial membranous projection and ventral, robust, posteriorly directed spine; in Hylister obliquus sp. nov.: (1) subgenital plate yellowish brown, with pointed projection near inner base of forceps; (2) penis lobe with ventral, short, narrow, posteromedially directed spine; in Traverella insolita sp. nov.: (1) subgenital plate strongly projected posteriorly, forming three broad and short projections; (2) penis lobe laterally sinuous and apically rounded, with a ventral, long, narrow spine curved toward the midline of the body. Modified keys of male imagos are provided for the three genera, whereas comments regarding their taxonomy are presented. Additionally, Hermanella mazama (Nascimento, Mariano & Salles 2012 in Lima et al. 2012), comb. nov., is proposed.

Three new species of Thraulodes Ulmer (Ephemeroptera: Leptophlebiidae) from Brazilian Amazonia are described: Thraulodes yara n. sp., Thraulodes yaciara n. sp. and Thraulodes ykamiaba n. sp., all based on imagoes. All three new species can be easily recognized by general color pattern and genitalia morphology. Thraulodes alboniger Kluge, 2020, known only from Peru, is recorded in Brazil. A remarkable gynandromorph case is presented for T. yara n. sp.

Simulium guianense Wise is a Latin American vector complex of black flies associated with transmission of the causal agent of human onchocerciasis (river blindness). An analysis of the chromosomal banding patterns of 607 larvae of S. guianense s. l. revealed a high level of variation involving 83 macrogenomic rearrangements across 25 populations in Brazil, French Guiana, and Venezuela. The 25 populations were assigned to 13 cytoforms (A1, A2, B1–B4, C, D, E1–E4, and F), some of which are probably valid species. Based on geographical proximity, a member of the B group of cytoforms probably represents the name-bearing type specimen of S. guianense and the primary vector in the last-remaining onchocerciasis foci in the Western Hemisphere. Cytoform B3 in Amapá State is implicated as an anthropophilic simuliid in an area currently and historically free of onchocerciasis. Distributions of cytoforms are associated with geography, elevation, and drainage basin, and are largely congruent with ecoregions. Despite extraordinarily large larval populations of S. guianense s. l. in big rivers and consequent production of female flies for dispersal, the cytoforms maintain their chromosomal distinction within individual rivers, suggesting a high degree of fidelity to the specialized breeding habitats—rocky shoals—of the natal rivers.

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