Nymphal description of Tricorythodes zagaia n. comb. and Tricorythodes pemonensis n. comb. (Ephemeroptera: Leptohyphidae) and first records from Colombia Author Molineri, Carlos Author Dias, Lucimar Gomes Author Gonzalez, Ivan Author Núñez-Avellaneda, Marcela text Zootaxa 2019 2019-04-12 4585 2 395 400 journal article 27329 10.11646/zootaxa.4585.2.13 346775c1-8991-4b8c-9b60-f3384aa66fc6 1175-5326 2637290 9DEB1059-C970-4BA6-9EEB-E434DDC30F0A Tricorythodes pemonensis (Molineri, Grillet, Nieto, Domínguez & Guerrero) comb. nov. ( Figs. 1–2 , 5–20 ) Macunahyphes pemonensis Molineri et al. 2011: 45 (male and female imagos); Belmont et al. 2015: 106 (male imago); Souto & Salles 2016: 10 (male imago). Material studied. One male nymph (pharate subimago, parts on slide) from Colombia , Vaupes , Mitú, San Pablo, Ceima-San Pablo stream, 104 m , N 1° 4' 31" – W 70° 14' 24" , 16/09/2016 , I. González col. (COMAC). Mature nymph . Length (mm): body, 3.0 mm, caudal filaments, 1.8 mm . Head without genal or frontal projections. General coloration yellowish shaded widely with gray. Mouthparts: labrum ( Fig. 5 ), hypopharynx shrunken while mounting; maxillary palp cylindrical, very small, 2-segmented with apical seta ( Fig. 9 ), distal brush of maxilla with about 10–15 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 5 setae and another large and pectinate ( Fig. 9 ); mandible and detail of prostheca as in Fig. 10 ; labium with paraglossae slightly longer than glossae ( Figs. 6–7 ) and with stout spine-like setae on apex, palp as in Figs. 6 and 8 . Thorax. Pronotum with rounded anterolateral corners ( Figs. 11–12 ). Foreleg ( Fig. 13 ): proximal portion of transverse row of long setae ( Fig. 13 ) at 0.7 of total femoral length from base; total length / maximum width of femur = 2.7; fore tarsal claw without marginal denticles and with a double row of 1–2+3 submarginal subdistal denticles ( Fig. 14 ). Middle leg similar to hind leg, except smaller in size, tarsal claw similar to foreleg except distally with 1+2 denticles. Hind leg ( Fig. 15 ): femur with few thin long setae on dorsum and along margins; total length / maximum width of femur = 3.4; tarsal claw without denticles. Abdomen ( Fig. 16 ). Small posterolateral spines present on segments VII–IX (smaller on IX), lateral flanges present on segments III–VI (strongly expanded on VI); IX sternite entire apically ( Fig. 16 ). Gill formula 3/ 3/3/3/2. Operculate gills subtriangular, large ( Figs. 18–19 ), translucent, shaded very slightly with gray: gills III–V with ventral lamellae with dorsal extension poorly developed ( Fig. 20 ), gill VI with two rounded lamellae. Caudal filaments with whorls of long setae at articulations. Distribution and ecological notes . Venezuela , Bolívar (Molineri et al. 2011). Brazil , Amapá (Belmont et al. 2015). Colombia , Vaupés . Ceima-San Pablo stream is a black water tributary of the Vaupes river, characterized by a low flow velocity. The substrate was formed mainly by sand, with leaf litter and plant material accumulated in some areas. Physico-chemical parameters of the water measured during the sampling: pH 5.4, temperature 24.7°C, electrical conductivity 5.93 µS/cm and dissolved oxygen 6.36 mg /L. Diagnosis. The adults of Tricorythodes pemonensis comb. nov. were sufficiently diagnosed in Molineri et al. (2011) and Belmont et al. (2015). The nymphs can be recognized by the following combination of characters: 1) maxillary palp very small, 2-segmented ( Figs. 9 ); 2) pronotum with rounded anterolateral projection ( Fig. 12 ); 3) legs relatively long and slender, covered with long setae ( Figs. 13 and 15 ); 4) fore tarsal claws without marginal denticles and with 1–2+3 submarginal denticles ( Fig. 14 ); 5) abdominal segments with lateral flanges on III–VI and small posterolateral spines on VII–VIII ( Fig. 16 ); 6) operculate gill large and subtriangular, gill formula 3/3/3/3/2 ( Figs. 18–20 ).