(Figures 1; 3–14)
Diagnosis. Mature nymph. 1) distal margin of labrum medially with spatulate setae; 2) maxillary palp 1.80 × length of galea-lacinia (Fig. 7); 3) segment II of maxillary palp without apical constriction (Fig. 7); 4) apical margin of lingua straight (Fig. 8); 5) segment II of labial palp with distomedial projection rounded and with anterior margin straight (Fig. 9); 6) segment III rectangular, length 0.71 × width (Fig. 9); 7) tarsal claw 1.25 × length of tarsus (Fig. 10 a); 8) posterior margin of abdominal terga without spines (Fig. 11); 9) paraproct with four marginal spines (Fig. 12).
Description. Mature male nymph. Length of body: 3.00 mm; cerci, terminal filament and antenna broken.
Body coloration (Fig. 1). Head. Coloration: light yellow. Antenna light yellow. Turbinate portion of compound eyes light brown. Thorax. Light yellow with medial spot on mesothorax. Foreleg (Fig. 10). Femur, tibia and tarsus light yellow. Abdomen. Terga IV with postero-medial brown mark, V with one medio-medial black mark, IX black, all terga with medioanterior sigilla strong pigmented (Fig. 1).
Body morphology. Head. Antenna with minute spines and fine, simple setae at apex of each segment (Fig. 3). Frons with two keels. Labrum (Fig. 4). Subrectangular, broader than long, with anterolateral margins rounded; length about 0.61 × maximum width; distal margin without medial emargination; ventral surface with robust spinelike setae on anterolateral and distal margins; dorsal surface with four to five short and spatulate setae medially near distal margin; dorsal surface covered by long and thin setae near distal margin. Right mandible (Fig. 5). Incisors deeply cleft in two sets; outer and inner set of incisors respectively with 3 and 2 denticles; prostheca slender, bifurcated at middle, both lobes pectinated; margin between prostheca and mola concave; tuft of spine-like setae at base of mola present; denticles of mola not constricted; apex of mola with two simple setae; lateral margin convex. Left mandible (Fig. 6). Incisors deeply cleft in two sets; outer and inner set of incisors respectively with 4 and 3 denticles; prostheca robust, bifid, inner lobe slender and outer blunt and strongly pectinate at base; margin between prostheca and mola concave; tuft of spine-like setae at base of mola present; subtriangular process wide; denticles of mola not constricted; lateral margin convex. Hypopharynx (Fig. 8). Lingua subquadrangular without apical lobe, slightly longer than superlingua; superlingua not expanded; short and thin setae scattered over distal margin of lingua and superlingua. Maxilla (Fig. 7). Maxillary palp long, 1.80 × length of galea-lacinia; segment II 1.09 × length of segment I, apex without constriction; maxillary palp with fine and simple setae scattered over surface. Labium (Fig. 9). Glossa basally broad, apically rounded and slightly longer than paraglossa; inner margin bare; outer margin with seven spine-like setae; apical margin with small spine-like setae; ventral surface covered with thin and long setae. Paraglossa curved inward; apex subtriangular; outer margin with one row of 13 robust spine-like setae; dorsal surface with one longitudinal row of four robust spine-like setae near inner margin; ventral surface with one longitudinal row of seven robust spine-like setae at middle. Labial palp with segment I 0.67 × length of segments II and III combined; segment I covered with micropores; segment II with distomedial projection rounded and with anterior margin straight, outer margin and distomedial projection covered with fine, long and simple setae; segment III rectangular, length 0.71 × width, covered with fine, long and simple setae on outer margin, ventral surface with robust spine-like setae near outer margin, distal margin with one row of robust spinelike setae. Thorax. Foreleg (Fig. 10 a). Ratio 2.0: 1: 1.2: 1.5. Forefemur. Length about 6.50 × maximum width; dorsally with row of 10 short concave and apically straight setae (Fig. 10 b); apex bare; ventrally with row of 18 spine-like setae. Tibia. Dorsally bare; ventrally with one row of ten short spine-like setae. Tibio-patelar suture present. Tarsus. Dorsally bare; ventrally with one row of 13 short spine-like setae. Tarsal claws 1.25 × length of tarsus, without row of denticles. Abdomen. Terga surface covered by scale-like triangular spines, micropores and short, fine and simple setae; posterior margin without spines (Fig. 11). Gills lost. Paraproct with four marginal spines, posterolateral extension broken and lost (Fig. 12). Cerci with small lateral spines on all segments (Fig. 13), terminal filament without spines (Fig. 14).
Etymology. Kethepiáli means fishing-bait in Baniwa, a language and indigenous tribe that inhabit the area where the species was collected. This word often is used to refer to mayflies, in general, by them.
Material examined. Holotype: nymph on slide, BRAZIL, state of Amazonas, São Gabriel da Cachoeira, small stream parallel to BR307, 13km, 26.viii. 2011, S00º04’ 44.6 ’’ / W067º00’ 15.9 ’’, Cruz P.V., Fernandes A. S. and Reis E. (colls.).