Tricorythopsis yucupe Dias, Salles & Ferreira

Molineri, Carlos, Grillet, Maria-Eugenia, Nieto, Carolina, Dominguez, Eduardo & Guerrero, Edmundo, 2011, New species and records for the mayfly families Caenidae, Leptohyphidae and Coryphoridae (Ephemeroptera, Pannota) from Venezuelan Guayana’s Uplands, Zootaxa 2750, pp. 39-50 : 46-47

Tricorythopsis yucupe Dias, Salles & Ferreira

( Figs. 18–22 )

Tricorythopsis yucupe Dias, Salles & Ferreira, 2008: 238 .

Material. Venezuela, Estado Bolivar: 2 nymphs from Soroape, N 5° 6' 29" – W 61° 34' 40", 935 m, 21/III/2006, EG, AMO and MEG cols.; 3 nymphs from Aponwao, N 5° 51' 2" – W 61° 27' 52", 1340 m, 27/IV/2007, EG, AMO, CA and MEG cols.; 1 nymph idem except date: 18/III/2006; 2 Ƥ imagos and 2 nymphs from Mareman-Parú, N 5° 44' 49" – W 61° 24' 6", 1308 m, 27/VI/2007, EG, AMO, CA and MEG cols.; 1 pharate 3 subimago (slide 513) from Kamá, N 5° 25' 11" – W 61° 13' 5", 1035 m, 24/XI/2005, EG, AMO, CA and MEG cols. Four nymphs and 1 Ƥ imago in MLBV, rest in IML.

Female imago ( Fig. 18 ). Length (mm): body, 2.7–2.8; forewing, 3.1–3.2; caudal filaments, 0.6. General coloration yellowish brown shaded gray. Head yellowish except occiput and ecdysial suture whitish, shaded gray on hind margin behind eyes. Antennae yellowish translucent. Thorax. Pronotum hyaline except lateral regions yellowish, shaded gray almost completely. Mesonotum yellowish brown shaded widely with gray; membranous filaments short and wide, medially curved. Thoracic sterna paler. Legs. Forelegs absent as usual in the genus, middle and hind legs yellowish with gray shading on femora (except small pale marks) and subapical band on tibiae. Wings. Membrane hyaline, longitudinal veins blackish. Abdomen ( Fig. 18 ). Segments yellowish white shaded widely with gray dorsally, except on anterior and posterior margins of all terga, on lateral zones of terga 1–6, and pale anterolateral marks on tergum 7. Caudal filaments yellowish translucent.

Male subimago, pharate. Body length, 2.7 mm. General coloration as female, except head paler, and abdominal terga 1–7 not shaded gray on lateral zones. Genitalia ( Figs. 20–21 ): styliger plate with long projections forming a columnar base for each forceps (sp in Fig. 20 ); penes slender, medially narrow with a moderately expanded apical part ( Fig. 21 ).

Nymphs ( Fig. 19 ). Length (mm): body, 2.2 (male)–2.7 (female); terminal filaments, 1.8 (male)–2.3 (female); cerci, 1.9 (male)–2.5 (female). As in the original description except that abdominal dorsal tubercles ( Fig. 19 ) are present on segments 6 to 9, much larger on 7–8 (original description reported them in terga 7–9).

Discussion. The nymphs are easily distinguished from other species of the genus by their large size and other characters listed in Dias et al. (2008), mainly the mesonotal paired keels on hind margin (mk in Fig. 19 ), the abdominal dorsal tubercles (at in Fig. 19 ), the operculate gills with 3 dark marks ( Fig. 22 ), the pale head without gray shading, contrary to the rest of body widely shaded with gray and black. The adults can be distinguished from the other species by the following combination of characters: 1) large size (body length> 2.7 mm); 2) abdomen shaded with gray almost completely except at lateral margins of terga 1–6 and pale anterior marks at each side of tergum 7 ( Fig. 18 ); 3) middle and hind femora shaded widely with gray or black; 4) penes slender, medially narrow but widening in distal portion ( Fig. 21 ). The combination of mesonotal keel, abdominal dorsal tubercles and projections on middle and hind coxae is also present in T. gibbus (Allen) and T. pseudogibbus Dias & Salles. The adults also share some features with T. gibbus (those of T. pseudogibbus are unknown): the widely pigmented femora, and the relatively great expansion of the distal lobes of the penes ( Fig. 21 ). Nevertheless, the strong narrowing of the penes on the medial portion, somewhat resembling those of T. artigas Traver , distinguishes T. yucupe from T. gibbus .

Ecology. Imagos were collected along the river margins, at night, during the rainy season (November 2005 and June 2007) and dry season (March 2006), using light traps, whereas, nymphs were collected within the rivers using a D-net. All the sampled rivers ( Figs. 25–26 ), flowing through the upland savanna ecosystem (935–1340 m), were large (30–100 m wide;> 4th order), non shaded, and bed-rock bottom rivers, with very acidic waters (pH=5).

Figures

FIGURES 14 – 22. Macunahyphes pemonensis sp. nov.; 14, male imago; 15, female imago; 16, male fore wing. Macunahyphes incognitus: 17, male fore wing. Tricorythopsis yucupe: 18, female imago; 19, nymph, l. v. (at = abdominal tubercle, mk = mesonotal keel); 20, styliger and forceps of pharate male adult (sp = styliger projections, f 1 = forceps segment 1, f 2 = forceps segment 2); 21, penes of pharate male; 22, operculate gill, d. v. (tl = transverse line).

FIGURES 23 – 26. Study sites: 23, Kaku Parú; 24, Kavanayén; 25, Mareman Parú; 26, Aponwao.