Tricorythodes zagaia (Souto & Salles) comb. nov.

(Figs. 3–4, 21–36)

Macunahyphes zagaia Souto & Salles, 2016: 11 (male subimago)

Material studied. Three nymphs (2 males and 1 female), from Colombia, Vaupés, Mitú, Erizo stream, 190m, N 1° 13' 20.3" – W 70° 11' 33", 15/09/2016, I. González col. (COMAC).

Mature nymph. Length (mm) of female: body, 4.1 mm, caudal filaments, 2.4 mm. Length (mm) of male: body, 3.1–3.3 mm, caudal filaments, 1.7–2.0 mm. General coloration yellowish. Head: without prominent genal and frontal projections, only thin setae present on genae and clypeus. Mouthparts: labrum with relatively shallow anteromedian emargination (similar to Fig. 5), covered by weak setae; mandibles with thin setae on outer margin; hypopharynx with medially straight lingua (Fig. 21); maxillary palp cylindrical, very small, 1-segmented with apical seta (Fig. 23), distal brush of maxilla with about 7–10 short and curved setae, with stipes 1.0 the length of galea-lacinia, inner proximal margin of the galea-lacinia (opposite to palpus) with row of 4 setae (Figs. 22); labium with paraglossae slightly longer than glossae, palp as in Figs. 24–25. Thorax. Pronotum with a small acute projection on anterolateral corners (Fig. 26). Foreleg (Fig. 27): proximal portion of transverse row of long setae at 0.6 of total femoral length from base (Fig. 27); total length / maximum width of femur = 3.6; fore tarsal claw broken off and lost. Middle leg similar to hind leg, except smaller in size. Hind leg (Fig. 28): femur with few thin long setae basally (3–4 long setae forming a basal transversal row) and along margins; total length / maximum width of femur = 4.4; tarsal claw with 6 marginal denticles and 1 subapical submarginal denticles (Fig. 29). Abdomen (Fig. 30). Large posterolateral spines present on segments VII–IX (smaller on IX), lateral flanges present on segments III–VI (strongly expanded on VI); IX sternite apically indented as in Figs. 30–31. Gill formula 2/3/3/ 3/2 (Figs. 32–36). Operculate gills subtriangular, large only with one ventral lobe (Fig. 33), translucent, shaded very slightly with gray: gills III–V with ventral most lamellae with dorsal extension poorly developed (Figs. 34– 35), gill VI (Fig. 36) with two rounded lamellae. Caudal filaments with whorls of long setae at articulations.

Distribution and ecological notes. Brazil, Amazonas (Souto & Salles 2016). Colombia, Vaupes. Erizo stream is a tributary of the Vaupes River, its waters are reddish and slow moving. The bottom was covered with leaf litter and some areas of accumulation of trunks and branches. Good conserved forest surrounded it. The following physico-chemical conditions of the water were measured at the time of collection: pH 5.6, temperature 25.1°C, electrical conductivity 8.07 µS /cm and dissolved oxygen 4.05 mg /L.

Diagnosis. The adults of Tricorythodes zagaia (Souto & Salles) comb. nov. can be recognized by its rounded penes similar to a trident (Souto & Salles 2016) (Fig. 31), and the nymphs by the following combination of characters: 1) maxillary palp very small, 1-segmented (Fig. 23); 2) pronotum with a small acute projection on anterolateral margin (Fig. 26); 3) legs relatively long and slender, covered with long setae (Figs. 27–28); 4) fore tarsal claws unknown (hind claw with 6 marginal denticles and with 1 submarginal denticles, Fig. 29); 5) abdominal segments with lateral flanges on III–VI and large posterolateral spines on VII–VIII (small on IX) (Fig. 30); 6) operculate gill large and subtriangular, gill formula 2/3/3/3/2 (Figs. 32–36)