Tricorythodes chalaza, 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 : 63-65

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

Male Imago. Diagnosis: 1) Vein CuP incomplete or absent ( Fig. 1 ); 2) inner margins of styliger plate projected ( Fig. 2 ); 3) basal swelling on segment II of forceps shaded with black ( Fig. 2 ); 4) penes pyramidal with lateral margins sclerotized, divided apically ( Fig. 2 ).

Nymph. Diagnosis: 1) Maxillary palpi one segmented with distal setae ( Fig. 7 ); 2) genal projections absent; 3) anterolateral projections of pronotum absent; 4) pronotum with prominent median tubercle ( Fig. 5 ); 5) tarsal claws with 13–14 denticles without distal setae ( Fig. 6 ); 6) dorsal surface of fore femora with transversal row of setae on submedian region ( Fig. 9 ); 7) femora narrow, bordered by a row of setae as in Figs. 8–9 ; 8) abdominal color pattern as in Fig. 4 ; 9) lateral margins of abdominal terga III–VII expanded, tergum VIII possessing posterolateral spines ( Fig. 4 ); 10) opercular gills triangular, yellow, with blackish shade ( Fig. 10 ).

Description. Male Imago: Length: 2.3–3.2mm body; 2.8–3.1mm wing. General coloration yellowish with black markings.

Head: Yellowish, with black markings on posterior margin and two brownish markings near posterior margin and ocelli. Ocelli grayish white surrounded by black. Scape and pedicel whitish suffused with brown; flagellum light brown.

Thorax: Pronotum whitish with black markings; two wide postero-lateral light brown markings on pronotum. Mesonotum light brown; lateral margins black on anterior and posterior ends; membranous filaments absent. Metanotum light brown. Sterna light brown.

Wings: Membrane hyaline; longitudinal veins grayish and cross veins translucent white. Base of wings and vein C shaded with gray. Vein ICuA usually not jointed at base to CuA; when jointed, vein ICuA becomes very light colored and translucent near junction. CuP incomplete or absent ( Fig. 1 ).

Legs: Coxae and trochanteres of fore legs whitish with black markings; coxae and trochanteres of mid and hind legs yellowish with black markings. Femora whitish possessing black markings. Mid legs more suffused with black than fore legs, only lightly shaded; hind leg more strongly suffused than fore and mid leg. Tibiae whitish. Tarsal segments and tarsal claws yellowish; fourth tarsal segment of fore legs lightly shaded with gray on basal half.

Abdomen: Whitish heavily suffused with black, so that only a median whitish longitudinal line can be seen on terga ( Fig. 3 ). Sterna translucent white, gonads can be seen by transparence on final terga. Caudal filaments whitish shaded by black becoming fainted toward apex.

Genitalia: Whitish; inner margin of forceps projected, basal swelling on segment II of forceps heavily shaded with black. Penes pyramidal with lateral margins strongly sclerotized; penes with apical division ( Fig. 2 ).

Variations: Some specimens had overall body coloration more heavily shaded with black, particularly on the head, thoracic terga and legs. In a few individuals, penes also presented a pair of black markings at base.

Female Imago: Unknown.

Mature Nymph: Length: 3.3–3.7mm body; 2.3–3.0mm caudal filaments. General coloration yellowish with black markings.

Head: Yellow with median region and posterior margin of head bearing black markings. Antennae yellowish. Mouthparts yellow. Maxillary palpi one-segmented with apical setae ( Fig. 7 ). Genal projection absent.

Thorax: Pronotum yellow with blackish markings; possessing a prominent tubercle medially ( Fig. 5 ). Anterolateral projection absent. Mesonotum yellow, bearing scattered blackish markings on lateral margins and between wing pads. Wing pads blackish. Sterna yellow.

Legs: Yellow; dorsal surface of femora shaded with black, more so on mid than on fore femora, and heavily on hind femora ( Figs. 8–9 ). Dorsum of fore femora with a transverse row of setae on sub median region ( Fig. 9 ). Tarsal claws with 13–14 denticles, without distal setae ( Fig. 6 ).

Abdomen: Yellow heavily shaded with black. Forming a yellow median longitudinal line and yellow sublateral areas on terga. Lateral expansions of abdomen yellow; lateral margins of segments III–VII expanded with postero-lateral spines on segment VIII. Posterior margin of terga bearing setae ( Fig. 4 ). Sterna yellow. Operculate gills triangular, yellow, with blackish shade. Remaining gills translucent white, suffused with black at base. Gill formula: 2–3–3–3–2 ( Figs. 10–15 ). Caudal filaments light brown bearing setae at joints.

Biology. Tricorythodes chalaza sp. nov. was found on rivers with slow current and sandy and muddy bottoms. Nymphs were collected in marginal banks and vegetation.

Etymology. “chalaz” meaning “tubercle”, in allusion to the presence of a prominent tubercle on pronotum.

Type material. Holotype: Brazil, RJ, Macaé, Córrego das Aduelas, 10m, 22o12'27.9''S / 41o50'24.2''W, 15.III.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1556). Paratypes: Brazil, RJ: Macaé, Córrego das Aduelas, 10m, 22o12'27.9''S / 41o50'24.2''W, 15.III.2009, Gonçalves, I.C. leg. 11 male imagoes ( DZRJ 1560); Macaé, Córrego das Aduelas, 28m, 22o11'10.4''S / 41o49'09.9''W, 15. IV.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1561); Macaé, 1o order tributary of Córrego das Aduelas, 15m, 22o12'11.8''S / 41o50'55.4''W, 15. IV.2009, Gonçalves, I.C. leg. 2 male imagoes ( DZRJ 1558); 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 1562); Macaé, Rio Macaé, 22o17'42.9''S / 41o52'48''W, 16. IV.2009, Gonçalves, I.C. leg. 1 male imago ( DZRJ 1557); same data, 3 male imagoes ( DZRJ 1559); same data except Ferreira-Jr, N. leg. 11 nymphs ( DZRJ 1563, DZRJ 1564, DZRJ 1566, DZRJ 1568, DZRJ 1570, DZRJ 1575, DZRJ 1576, DZRJ 1577); same locality, 21.I.2008, Ferreira-Jr leg. 2 nymphs ( DZRJ 1565 and DZRJ 1574); same locality, 2005, no leg. 4 nymphs ( DZRJ 1567, DZRJ 1569, DZRJ 1573); Macaé, Sana, Córrego Alegre, 22o15'38.8''S / 42o10'08.2''W, 19.II.2009, Gonçalves, I.C. leg. 1 nymph ( DZRJ 1571); Brasil, RJ, Nova Friburgo, Cascata, Rio Macaé, 22o22'03.2''S / 42o15'27.8''W, 08.III.2009, Gonçalves, I.C. leg. 2 nymphs ( DZRJ 1572 and DZRJ 1578).

Discussion. T. chalaza sp. nov. is similar to T. bullus by sharing, on the male imagoes: vein CuP incomplete and penes pyramidal with lateral margins strongly sclerotized. Despite the resemblance, imagoes of the new species can be differentiated by having styliger plate projected on inner corner and basal swelling of segment II of the forceps heavily shaded with black, characteristics lacking on T. bullus . Moreover, in T. chalaza sp. nov. the vein CuP may be incomplete or absent, whereas in T. bullus this vein is always present though incomplete.

Regarding the nymphs, T. bullus and T. cristatus also present a tubercle on pronotum as T. chalaza sp. nov. However, the new species can be differentiated from both by the absence of tubercles on head and mesothorax. An additional difference between these speciesis the number of denticles on tarsal claws: 13–14 in T. chalaza sp. nov., 16–18 in T. cristatus and 8–11 in T. bullus .

Figures

FIGURES 1 – 3. Tricorythodes chalaza sp. nov. (male imago). 1 — Forewing, 2 — Genitalia, and 3 — Abdominal color pattern (scale: 1.0 mm except Fig. 2: 0.1 mm).

FIGURES 4 – 15. Tricorythodes chalaza sp. nov. (nymph). 4 — Abdominal color pattern, 5 — Head and thorax (lateral view), 6 — Tarsal claw, 7 — Maxilla, 8 — Hind leg, 9 — Foreleg, 10 — Gill II (dorsal view), 11 – 15 — Gills II – VI (ventral view) (scale: Figs.: 4 – 5 and 8 – 9: 1.0 mm; Figs.: 6 – 7 and 10 – 15: 0.1 mm).