Homoeoneuria (Homoeoneuria) watu sp. n. (Figs. 1–13) Male imago (in alcohol) (Figs. 1–2) Body length: 8.0– 8.4 mm. Forewings length: 7.9–8.1 mm. Caudal filaments length: 3.1–3.3 mm. Head (Fig. 1). General coloration dark brown. Antennae dark brown. Basal half of lateral ocelli brown, remainder and median ocellus transparent white. Eyes grayish-black. Thorax (Fig. 1). General coloration dark brown, membranous areas pale yellow. Pronotum with prominent posteromedian pale yellow spot almost reaching anterior margin. Wings (Fig. 1): membrane of forewings iridescent blue, veins brownish. Legs: coxae and trochanter of foreleg dark brown, of mid and hind legs blackish; femora, tibiae, and tarsi of foreleg slightly washed with brown; remainder of mid and hind legs whitish. Abdomen. Terga blackish, with black markings (Fig. 1). Sterna lighter than terga, with whitish markings, and with median longitudinal pale band. Intersegmental membranae yellowish on terga, whitish on sterna. Genitalia (Fig. 2): penis dark brown. Caudal filaments orange, setae black. Female imago (in alcohol) Body length: 8.7 mm. Forewings length: 8.8 mm. Caudal filaments length: broken-off and lost. Similar to male imago, except for absence of markings on abdominal sterna. Mature nymph (in alcohol). (Figs 3 – 13) Body length: 8.5–9.0 mm. Caudal filaments length: 3.4–3.7 mm. Head (Figs. 3, 11 – 12). General coloration yellowish washed with brown, heavily washed with brownishorange between compound eyes and ocelli; ocelli white. Eyes brownish-black. Vertex with pair of small median tubercles. Antennae pale yellow; pedicel with short, thick setae (Fig. 4). Mouthparts: galea-lacinia of maxillae with submarginal row of 20–21 long, spinous setae (Fig. 5); posterior margin of superlingua strongly curved (Fig. 6); segment 1 of labial palpi approximately 3/4 length of segment 2. Thorax. Pronotum pale yellow washed with brown, with orange marks; anterior margin with pair of small tubercles (Figs. 3 and 12). Mesonotum pale yellow with large, median, whitish spot followed by an orange, median, longitudinal stripe. Metanotum orange. Legs whitish. Foreleg (Figs. 7, 8 and 12): coxae tinged with orange; tibiae strongly bowed, maximum width approximately 3/5 maximum width of femora; distance of tarsi from apex of tibiae approximately 3/4 maximum width of tibiae; apical portion of tibiae straight. Middle leg (Fig. 9): tarsal claws approximately 1/3 length of tarsi and 1/2 length of tarsal claws of hind legs. Hind leg (Fig. 10): tarsal claws 2/5 length of tarsi. Abdomen (Fig. 13). Terga 1–3 yellowish-white washed with orange; posterior half of terga 1 and anterior margin of terga 2 and 3 hyaline; terga 4–9 whitish washed with orange and with dark grey markings near posterior margins (depending on the specimens, these markings can be more widespread); terga 10 whitish, slightly washed with orange and with two white markings near posterior margins. Sterna whitish. Caudal filaments pale yellow, setae pale yellow, except for a tuft of black setae on apical 2/3. Type material. Holotype: male imago, Minas Gerais, Parque Estadual do Rio Doce, Rio Belém (19º 35' 076'' S; 42º 33' 980'' W, 257m), 25/x/2005, C.N. Francischetti, F.F. Salles, leg (UFES). Paratypes: three male imagos, one female imago, ten nymphs, same data as holotype (one male imago, one female imago and five nymphs at UFES; remainder at INPA). Etymology: Watu, how the Krénak people, a small indigenous group who still inhabits the region, call the Doce River. The epithet is an allusion to the Rio Doce State Park, where the new species was exclusively found. Diagnosis. Homoeoneuria (H.) watu sp.n. can be distinguished from the other described species of the genus by the following combination of characters: In the adult stage, (1) pronotum with prominent posteromedian pale yellow spot almost reaching anterior margin; (2) abdominal color pattern; (3) shape of penes (Fig. 2). In the nymph, (1) head heavily washed with brownish-orange between compound eyes and oecelli (Fig. 11); (2) antennal pedicels with short, thick setae (Fig. 4); (3) small paired tubercles present on vertex of head and anterior margin of pronotum (Figs. 3 and 12); (4) galea-lacinia of maxillae with submarginal row of 20–21 long, spinous setae (Fig. 5); (5) abdominal color pattern (Fig. 13).

Published as part of Salles, F. F., Francischetti, C. N. & Soares, E. D. G., 2009, The presence of Homoeoneuria s. s. (Ephemeroptera: Oligoneuriidae) in South America with the description of a new species, pp. 53-60 in Zootaxa 2146 (1) on pages 54-57, DOI: 10.11646/zootaxa.2146.1.4, http://zenodo.org/record/5319972