Tricorythodes diasae, Gonçalves, Inês C., Da-Silva, Elidiomar R. & Nessimian, Jorge L., 2010

Gonçalves, Inês C., Da-Silva, Elidiomar R. & Nessimian, Jorge L., 2010, Two new species of Tricorythodes Ulmer, 1920 (Insecta, Ephemeroptera) from Southeastern Brazil, Zootaxa 2721, pp. 62-68 : 65-68

Tricorythodes diasae sp. nov. Gonçalves, Da-Silva and Nessimian

Male Imago. Diagnosis: 1) Vein CuP of wings absent or incomplete ( Fig. 16 ); 2) distal 3/4 of hind legs black; 3) inner margins of styliger plate projected ( Fig. 17 ); 4) penes rectangular with lateral margins sclerotized, forming two distal lobes inserted apico-dorsally with rounded margins ( Fig. 17 ).

Nymph. Diagnosis: 1) Maxillary palpi one-segmented with distal setae ( Fig. 22 ); 2) Genal projection absent; 3) anterolateral projections of pronotum absent; 4) Tubercles absent on head and thorax; 5) tarsal claws with 10–11 denticles, without distal setae ( Fig. 23 ); 6) dorsal surface of fore femora with transversal row of setae on median region ( Fig. 21 ); 7) femora narrow, not bordered by a row of long setae ( Figs. 20–21 ); 8) lateral margins of abdominal terga III–VI expanded, terga VII–VIII bearing posterolateral spines ( Fig. 19 ); 9) opercular gill triangular, yellowish, with scattered blackish dots ( Fig. 24 ).

Description. Male Imago: Length: 2.8–3.2mm body; 2.7–3.0mm wing. General coloration translucent white with black markings.

Head: Brown suffused with blackish spots. Eyes and ocelli black. Scape, pedicel and flagellum whitish washed with brown.

Thorax: Pronotum translucent whitish washed with blackish spots, lateral margins brown. Mesonotum brown, posterior margin blackish. Membranous filaments short, inconspicuous. Metanotum whitish, heavily shaded with black. Prosternum whitish with blackish dots. Meso and metasternum yellowish.

Wings: Membrane hyaline, veins blackish. Basal third of Sc possessing blackish spots along the vein. Vein CuP absent or incomplete ( Fig. 16 ).

Legs: Forelegs with coxae, trochanteres and femora yellowish-white; tibiae, tarsus and tarsal claws whitish; last tarsal segment faintly washed with black. Mid legs with coxae, trochanteres and femora yellowish-white; tibia, tarsus and tarsal claws whitish. Hind legs with coxae, trochanteres and basal fourth of femora yellowish white; distal 3/4 of femora and tibia washed with black; tarsus and tarsal claws whitish.

Abdomen: Terga translucent white heavily washed with black ( Fig. 18 ). Sterna translucent white; lateral margins of sterna I–IV washed with black; remaining segments becoming more heavily shaded towards end of the abdomen. Caudal Filaments translucent white, basal segments washed with black.

Genitalia: Forceps and penes translucent white. Inner margin of forceps projected. Penes rectangular with lateral margins sclerotized; possessing two distal lobes with lateral margins rounded; distal lobes inserted dorsoapically ( Fig. 17 ).

Female Imago: Unknown.

Mature Nymph: Length: 4.5mm body; 2.7–3.2mm caudal filaments. General coloration yellowish with blackish markings.

Head: Yellowish; washed with black between eyes and ocelli. Scape, pedicel and flagellum yellowish. Mouthparts yellow; maxillary palpi one-segmented with apical setae ( Fig. 22 ). Genal projection absent.

Thorax: Pronotum yellow; heavily shaded with black. Antero-lateral projection absent. Mesonotum yellowish; metanotum whitish yellow. Sterna yellowish.

Legs: Yellowish. Fore femora with median transversal row of long setae ( Fig. 21 ). Hind femora dorsally shaded with faint blackish ( Fig. 20 ). Tarsal claw with 10–11 denticles ( Fig. 23 ).

Abdomen: Terga yellowish heavily shaded by blackish. Sterna yellowish with lateral margins shaded with black. Lateral margins of segments III–VI expanded; segments VII and VIII with postero-lateral spines ( Fig. 19 ). Operculate gills triangular; all gills yellowish with scattered blackish dots. Gill formula 2–3–3–3–2 (figs. 24–29). Caudal filaments yellowish, with row of long setae on joints.

Variations: In some specimens, shading on terga VIII–X formed a pair of yellowish marks medially.

Biology. Tricorythodes diasae sp. nov. nymphs were found on pool litter and marginal banks on slow current areas of rivers. These substrata were usually covered by sediment, commonly found covering the body of nymphs of the genus.

Etymology. The new species is named in honor of Lucimar G. Dias, friend and researcher of Ephemeroptera .

Type material. Holotype: Brazil, RJ, Macaé, Glicério, Córrego Duas Barras, 146m, 22o14'41.2''S 42o03'30.2'', 22.III.2009, Jardim G.A. & Sampaio, B.H.L. leg. 1 male imago ( DZRJ 1579); Paratypes: Brazil, RJ: Macaé, Frade, Rio das Pedras, 262m, 22o14'28''S /42o06'05.7'', 20.III.2009, Gonçalves, I.C. leg. 2 males imagoes ( DZRJ 1580); Macaé, Estrada Frade-Sana, Rio São Pedro, 426m, 22o13'45.1''S / 42o07'39.6''W, 20.III.2009, Gonçalves, I.C. leg. 2 male imagoes ( DZRJ 1581); Macaé, Córrego das Aduelas, 10m, 22o12'27.9''S / 41o50'24.2''W, 15.III.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1582); Macaé, 1o order tributary of Córrego das Aduelas, 15m, 22o12'11.8''S / 41o50'55.4''W, 15. IV.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1584); Macaé, Cachoeiros de Macaé, Rio Macaé, 68m, 22o25'49.5''S / 42o12'06.6''W, 05. IV.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1585); Casimiro de Abreu, Figueira Branca, Ribeirão da Luz, 77m, 22o25'48.2''S / 42o12'14.9''W, 05. IV.2009, 21 male imagoes ( DZRJ); Nova Friburgo, Lumiar, Córrego dos Patos, 644m, 22o24'08.6''S / 42o19'14.2''W, 06.III.2009, Gonçalves, I.C. leg. 3 male imagoes ( DZRJ 1588); Nova Friburgo, Lumiar, Toca da Onça, Rio Bonito, 608m, 22o24'05.6''S / 42o19'17.8''W, 05.III.2009, Gonçalves, I.C. leg. 8 male imagoes ( DZRJ 1589 and DZRJ 1590); same locality, 2008, Nessimian, J.L., Dumas, L.L. & Santos, A.P.M. leg. 1 male imago ( DZRJ 1591); Nova Friburgo, Cascata, Rio Macaé, 370m, 22o22'03.2''S / 42o15'27.8''W, 08.III.2009, Alecrim, V.P. leg. 2 nymphs ( DZRJ 1592 and DZRJ 1593); Nova Friburgo, Encontro dos Rios, Rio Macaé, 515m, 22o23'37.1''S / 42o18'20.6''W, 08.III.2009, Gonçalves, I.C. leg. 3 nymph ( DZRJ 1594); Nova Friburgo, Lumiar, Rio Boa Vista, 900m, 22o19'02.1''S / 42o17'28.5''W, 15.XI.2008, Gonçalves, I.C. leg. 1 nymph ( DZRJ 1595); Nova Friburgo, Lumiar, Rio Macaé, 600m, 22o21'47.3''S / 42o18'37.6''W, 16.XI.2008, Gonçalves, I.C. leg. 1 nymph ( DZRJ 1596).

Discussion. Nymphs of Tricorythodes diasae sp. nov. resemble those of T. barbus Allen, 1967 by having abdominal segments III–VI expanded as well as lack of tubercles on head and thorax, and no subapical black markings on tibiae and tarsi. In spite of that, they can be identified by the maxillary palpi (one-segmented with apical setae), lack of genal projection and antero-lateral projections on prothorax, posterolateral spines of the abdomen on segments VII–VIII, and tarsal claw with 3–4 marginal denticles and 1–2 submarginal denticles. Whereas T. barbus presents maxillary palpi 3-segmented also with apical setae, genal projection and antero-lateral projections of prothorax present, posterolateral spines of the abdomen on segment VII and tarsal claw with one pair of submarginal denticles.

Male imagoes of T. diasae sp. nov. are quite unique among Tricorythodes species from possessing lobes of penes distinctively separated and inserted dorso-appically on penes, with rounded margins.

Figures

FIGURES 16 – 18. Tricorythodes diasae sp. nov. (male imago). 16 — Forewing, 17 — Genitalia, and 18 — Abdominal color pattern (scale: 1.0 mm, except Fig. 17: 0.1 mm).

FIGURES 19 – 29. Tricorythodes diasae sp. nov. (nymph). 19 — Abdominal color pattern, 20 — Hind leg, 21 — Foreleg, 22 — Maxilla, 23 — Tarsal claw, 24 — Gill II (dorsal view), and 25 – 29 — Gills II – VI (ventral view) (scale: Figs. 19 – 21: 1.0 mm, Figs. 22 – 29: 0.1 mm).