Traverella maranhensis Nascimento, Lima & Azevedo, 2019

Nascimento, Stênio R. S., Lima, Lucas R. C., Mariano, Rodolfo & Azevêdo, Carlos A. S., 2020, New species and stages description of Traverella Edmunds, 1948 (Ephemeroptera Leptophlebiidae) from Northeast Brazil, Zootaxa 4861 (3), pp. 411-422 : 418-421

Traverella maranhensis Nascimento, Lima & Azevedo, 2019

( Figs 6–8 )

Traverella maranhensis Nascimento, Lima & Azevedo, 2019: 196 . Diagnosis. Male Imago: 1) vein ICu1 of forewings free basally; 2) subgenital plate forming two broad, lateral projections with two narrow, long, dorsally recurved spines; 3) penis lobe divided on distal ¾; 4) penis lobe triangular and apically rounded, with a long, ventral spine both slightly curved and directed to midline (adapted from Nascimento et al. 2019). Nymph: 1) clypeus with a triangular anteromedial projection extending forward and curved slightly upward; 2) labrum rectangular with anteromedial emargination; dorsal proximal row with 7–8 long setae interrupted medially; 3) mandible with outer margin forming an angle of almost 90º, without dorsal row of setae; 4) gills I–VII tapering gradually, with lateral tracheation, inner margin with 12–13 filaments along the entire length of gill and outer margin apically with 3–4 filaments.

Description. Mature Nymph. Length: body, 5.1–5.8 mm; antenna, 2.6–2.7 mm; cerci, 3.9–4.1 mm; terminal filament, 4.5–5.1 mm. General coloration yellowish brown ( Figs 6–8 ).

Head. Yellowish brown, washed with gray. Upper portion of male compound eye orangish, lower portion black. Antenna whitish yellow. Clypeus with triangular anteromedial projection extending forward and curved slightly upward ( Figs 6B , 7A ), lateral margin strongly concave, maximum width of labrum 1.5× maximum width of clypeus. Mouthparts ( Figs 7 A–E). Labrum ( Fig. 7A ) whitish brown, rectangular with anteromedial emargination; dorsal proximal row with 7–8 long setae interrupted medially; numerous ventral setae directed obliquely to sagittal plane; maximum width 3.5× maximum length. Mandible ( Fig. 7D ) translucent, dark brown near to incisors and molars; outer margin forming angle of almost 90º; without dorsal row of setae. Maxilla ( Fig. 7E ). Galea-lacinia with prominent curved tusk on inner apical angle (nearly half of the apical width of galea-lacinia). Hypopharynx as in figure 7B. Labium as in figure 7C.

Thorax. Terga yellowish brown, irregularly washed with grayish brown; pronotum with submedial stripe and lateral margin grayish brown; pleura brownish, washed with dark gray; sterna whitish yellow ( Fig. 6C ). Legs. Whitish; coxae washed with grayish brown. Legs I and II ( Figs 8A, C ) femur slightly washed with light brownish. Legs III ( Fig. 8E ) femur with subapical band and dorsal grayish brown mark. Femora with long setae and spine-like setae along external margin; dorsal surface covered with spine-like setae, absent in femur I. Tibia I ( Fig. 8A ) with many short spine-like setae along inner margin and long and thin setae along outer margin; tibia II ( Fig. 8C ) with long and thin setae along outer margin and row of spine-like setae on external margin; tibia III ( Fig. 8E ) with spine-like setae and long setae on external margin and long spine-like setae on inner and apical margins. Tarsal claws strongly hooked ( Fig. 8B ) with minute denticles basally and 5–6 median denticles subequal in size, without accessory denticles.

Abdomen. Terga light brown, with segments VI–X darker. Sterna whitish, segments VII–VIII washed with grayish brown ( Fig. 6C ). Gills grayish, present on segments I–VII tapering gradually, with lateral tracheation ( Fig. 8D ); inner margin with 12–13 filaments along entire length of gill and outer margin apically with 3–4 filaments. Caudal filaments yellowish.

Biology. The nymphs co-occur at the same collection sites as T. excelsior sp. nov.

Material examined. Brazil, Maranhão State, 1 ♂ imago (reared), exuviae mounted on slides ( UFVB–EP00196 ), Caxias municipality, Pé da Serra, Rio Itapecuru , S05°07’28.51”, W43°33’02.26”, 68 m a.s.l., 06.xii.2019, Nascimento, SRS; Jesus, JIS cols ; 3 ♂ nymphs (MZUESC–eph0703), same data except, 02.ii.2018, Nascimento, SRS; Jesus, JIS cols ; 2 ♂ nymphs (MZUESC–eph0704), same data except, 14.vii.2020, Nascimento, SRS col .

Discussion. The nymphal stage of T. maranhensis seems to be related to T. (Z.) calingastensis by the presence of a row of spine-like setae on posterior margin of foretibia, a frontoclypeal projection and 5–6 tarsal claws. They can be distinguished mainly by the presence of a prominent tusk on galea-lacinia in T. maranhensis that is absent in T. (Z.) calingastensis . The frontoclypeal projection in T. maranhensis is triangular and short, reaching the basal half of labrum, while in T. calingastensis is slender and long, exceeding the anterior margin of the labrum.

Figures

FIGURE 6. Traverella maranhensis. nymph; A) habitus; B) lateral view of head (arrow indicating the clypeal projection); C) detail of abdominal sterna; D) lateral view of nymph. Scale bars in mm: A, C and D = 2; B = 0,5.

FIGURE 7. Traverella maranhensis. nymph; A) labrum, dorsal view; B) hypopharynx, ventral view; C) labium, dorsal view; D) left mandible; E) maxilla, ventral view. Scale bars in mm: A–E = 0,5.

FIGURE 8. Traverella maranhensis. nymph; A) foreleg; B) anterior tarsal claw; C) middle leg; D) Gill IV; E) hind leg. Scale bars in mm: A, C and E = 1; B = 0,2; D = 0,5.