Caenis dominguezi Malzacher

Caenis dominguezi Malzacher (Figs. 31–49, 160, 167, 174, 181)

Caenis dominguezi Malzacher, 2001: 9 (male).

Type material (IFML). Holotype male imago from ARGENTINA: Córdoba, San Esteban, 10-X-1981, E. Domínguez col.; 5 paratypes male imagos, same data.

Additional material (IFML). Four male imagos from ARGENTINA: Catamarca, dpto. Andalgalá, Las Estancias, El Lindero, S 27° 28' 01" – W 66° 00' 37", 1530 m, 19-IV-2003, E. Domínguez & G. Cuezzo cols; 22 nymphs from Catamarca, dpto. Andalgalá, Las Estancias, río de El Lindero, S 27° 28' 18" – W 66° 00' 54", 1594 m, 28-III-2006, C. Molineri col; 19 nymphs, 3 female and 1 male imagos (reared) from Catamarca, dpto. Andalgalá, Las Estancias, río Pisavil, S 27° 27' 5" – W 66° 00' 10", 1548 m, 28-III-2006, C. Molineri col; 20 nymphs from Catamarca, río Huacra, S 28° 00' – W 65° 33', 24-VIII-2004, M. Peralta col.; 1 male imago and 12 nymphs from Catamarca, Bañado de Ovanta, S 28° 08' – W 65° 19', 24-VIII-2004, M. Peralta col.; 1 nymph from Córdoba, Cavalanga, Arroyo Las Salinas, S 31°23' – W 64°32', 2-X-1999, V. Manzo & S. Cohen cols.; 3 nymphs and 10 male imagos from Córdoba, Achiras, 9-XII-1995, M. Gualdoni col.; 6 male imagos from Córdoba, Los Espinillos, 13-IX-1997 (nuptial flight 11 h am), C. Molineri & C. Nieto cols., 13 nymphs same data except date, 15-IX-1997; 10 nymphs from Córdoba, Pampa de Achala, El Cóndor, 23-X-1996; 5 nymphs from Santiago, Guasayán, Maquijata, S 28° 14' 50" – W 64° 48' 32", 415 m, 14-VI-2005, F. Romero col.; 1 nymph from Salta, Aº Zanjon Seco, 16-V-2006, S 23° 41' 11", W 64° 34' 18", 430 m, N. von Ellenrieder col.; 20 nymphs from BOLIVIA: Tarija, Gran Chaco, S 21° 55' 46.2" – W 63° 46' 26.1", 810 m, río Caraparí, cerca de Caraparí, 10-X-2004, C. Molineri & V. Manzo cols.

Male imago. See Malzacher (2001).

Female imago. Similar to male imago. Length: body, 4.5–4.7 mm; fore wing, 4.3–4.5 mm; caudal filaments, 2.5–3.0 mm. Katepisternum not paler than rest of mesopleural sclerites. Abdominal pleurae whitish with small grayish marks. Posteromedian membranous projection on tergum II relatively short. Egg mass whitish to yellowish-white. Ninth sternum broadly rounded apically. Caudal filaments yellowish except basal segment brownish.

Mature nymph (Fig. 160). Length of female: body, 5.7–6.5 mm; caudal filaments, 3.7–4.5 mm. Length of male: body, 4.4–4.8 mm; caudal filaments, 2.5–4.0 mm. General coloration brown to light-brown. Head (Fig. 167): occiput without marks except a small gray area at posterolateral corners; transverse blackish band between ocelli, anteriorly to median ocellus a triangular pale area is present, venter of head much paler than dorsum; hind margin of head with small simple setules. Antennae: pedicel and scape yellowish-brown, flagellum paler. Mouthparts: labrum (Fig. 31) with a pair of small submedian protuberances on anteromedian emargination; mandibles as in Figs. 143–144, left mandible with anterior denticles of molae markedly protruding (Fig. 143); lingua of hypopharynx with slightly concave fore margin (Fig. 156); labium with paraglossae rounded and relatively short, segment II of labial palp 1.32–1.77 times the length of segment III. Thorax yellowish to brownish. Pronotum shaded with black as in Fig. 35, with a pair of submedian large pale areas. Mesonotum with two pairs of submedian pale blotches, and another larger pair on wingpad bases. Metanotum and thoracic sterna paler than dorsum. Legs whitish-yellow with a small subapical gray mark in the dorsal surface of femora (Figs. 36–38). Coxal projections with irregular margin and long setae, coxal projections II–III medium sized and rounded (Figs. 39–40). All femora with numerous scattered spine-like setae on the dorsum (more numerous on femora II–III) (Figs. 36–38). All tarsi with a longitudinal row of simple setae, tarsi II and III with an additional row of plumose setae (1–3 setae on tarsus II, 6 on tarsus III). Tarsal claws I–II with 6–10 denticles of irregular size but increasing toward apex (Fig. 41–42); tarsal claw III with 23–25 denticles becoming larger from base to apex, abruptly decreasing in size medially, and increasing again toward apex (Fig. 43). Abdomen light-brown shaded with gray, posteromedian projection of tergum II well developed, curved posteriorly (Figs. 48). Terga I–II shaded with gray except on lateral areas, terga III–VII shaded more slightly with gray except medially and laterally, terga VIII–X shaded more strongly except suboval pale marks on posterolateral corners of terga VIII–IX (Fig. 174). Abdominal sterna paler (Fig. 181), slightly shaded with gray, sometimes with cuticular yellowish coloration on anterior margins of sterna VII–IX. Gills: operculate gills (Fig. 44) uniform yellowish-brown, with numerous simple setae and microspines dorsally, microtrichia on ventral submarginal row elongated or subtriangular (Figs. 45–46); remaining gills bicolor, half whitish and half grayish (Fig. 47). Caudal filaments yellowish-white. Ninth sternum with a U-shaped median indentation (Fig. 49), rear margin with relatively strong simple setae (not bent apically).

Diagnosis. C. dominguezi can be distinguished from the other species of the genus by the following combination of characters. In the adult: 1) general coloration dark brown; 2) prosternal triangle anteriorly pointed or open; 3) median filament on abdominal tergum II long; 4) fore legs as long as body; 5) forceps apically rounded; 6) central sclerite of styliger with blurred outline; 7) apophyses of styliger sclerite bent inwards; 8) lobes of penes laterally projected, apically acute to somewhat rounded; 9) coloration of mesothoracic katepisternum similar to rest of mesothorax; 10) posterolateral zones of sternum IX strongly dark-colored. In the nymph: 1) occiput without marks, head color pattern as in Fig. 167, hind margin with small simple setules; 2) meso- and metacoxal processes present, rounded and with long bristles; 3) tarsi with relatively medium length setae, 3–6 plumose setae on tarsi II and III (Figs. 36–37); 4) tarsal claws not strongly curved apically (Figs. 41–43), denticles on tarsal claw III becoming larger from base, abruptly decreasing in size medially, and increasing size again toward apex; 5) abdominal color pattern as in Figs. 174 and 181; 6) labrum with slightly rounded lateral margins and with two submedian protuberances on anteromedian emargination (Fig. 31); 7) segment II of labial palp 1.32–1.77 times the length of segment III; 8) lingua of hypopharynx with concave fore margin (Fig. 156); 9) IX sternum with a U-shaped apicomedial indentation (Fig. 49), rear margin with relatively strong simple setae; 10) dorsum of gill II only with simple setae (Fig. 44); 11) dorsum of all femora with numerous long spines (Figs. 36–38); 12) abdominal gills III–VI bicolor half white and half gray (Fig. 47).

Distribution (Fig. 188). Argentina (Córdoba, Catamarca, Santiago, Salta), Bolivia (Tarija). Distributional records include localities from Chaco and transitional (Chaco-Yungas) regions.