Paracloeodes atroari Nieto & Salles, 2006

Cruz, Paulo Vilela, Salles, Frederico Falcão & Hamada, Neusa, 2018, Contribution to the taxonomy of Paracloeode s Day 1955 (Ephemeroptera: Baetidae) from South America, Zootaxa 4403 (1), pp. 1-49 : 6-9

Paracloeodes atroari Nieto & Salles

( Figures 4–5)

Paracloeodes atroari Nieto & Salles 2006: 8 .

Diagnoses. Male imago. 1) stigmatic area of forewing hyaline ( Figs 4J and 4K); 2) hind wing absent; 3) abdominal terga and sterna I–VI white and VII–X brown ( Fig. 4F); 4) posterior margin of styliger plate convex, with pointed spine medially ( Fig. 4H); 5) posterior margin of styliger plate with one rounded protuberance projected ventrally ( Fig. 4I).

Mature nymph. 1) frons elevated, forming keel ( Figs 4D and 4E); 2) distolateral margin of labrum with bifid and pectinate setae ( Fig. 13 in Nieto & Salles 2006); 3) incisors of right mandible cleft ( Fig. 15 in Nieto & Salles 2006); 4) distomedial projection of labial palp 2.0–2.3× width of segment III ( Fig. 17B in Nieto & Salles 2006); 5) hind wing pads absent; 6) anterior surface of forefemur without setae near dorsal margin ( Fig. 5B); 7) anterior surface of foretibia without setae ( Fig. 5B); 8) anterior surface of tarsus without setae ( Fig. 5B); 9) ventral margin of tarsus with one row of stout setae ( Fig. 5B); 10) tarsal claw 0.5× length of tarsus; 11) cercus with short spines on each segment, and long spines laterally ( Fig. 5D); 12) paracercus with lateral spine on few segments ( Fig. 5F); 13) body color pattern as in figures 4A, 4B and 4C.

Description. Male Imago. Length: Body 3.1 mm; cercus 3.8 mm; forewing 2.8 mm; antenna 0.4 mm; tibia I 0.7 mm; tibia III 0.4 mm (n=1). Head brown. Turbinate portion of compound eyes light brown. Scape, pedicel and flagellum light brown. Dorsal portion of turbinate eyes slightly oval ( Figs 4F and 4G); length 1.2× width; stalk height 0.6× height of dorsal portion. Thorax ( Figs 4F and 4G) light brown. Anteronotal and metascutellar protuberance rounded. Legs whitish. Leg I: tibia 1.1× length of femur; tarsus 1.1× length of femur. Leg III: tibia 0.8× length of femur; tarsus 0.5× length of femur. Forewing ( Figs 4J and 4K) with light brown veins; stigmatic area with three to six cross veins not reaching subcostal vein; marginal intercalary veins paired, absent between IMP1 and A; length of each intercalary vein 0.5× distance between adjacent longitudinal veins; length of forewing about 2.7× width. Hind wing absent. Abdomen ( Figs 4F and 4G) with terga I–VI white, VII–X brown; tracheation black. Sterna I–VI light brown, VII–X brown. Caudal filaments lost. Genitalia ( Figs 4H and 4I) with forceps light brown. Forceps segment I narrow at base and with distoproximal projection rounded; 0.6× length of segment II; distance between inner margins of forceps 0.5× distance between outer margins of forceps. Forceps segment III 0.3× length of segment II. Posterior margin of styliger plate convex, with long pointed spine medially, projected ventrally; one rounded protuberance ventrally ( Figs 4H and 4I, red arrows).

Complementary description. Mature nymph. Length of body: 2.8–3.07 mm; cercus: 1.32 mm; paracercus: 1.27 mm (n=2). Head with frons elevated, forming keel ( Figs 4D and 4E, black arrows). Antenna ( Fig. 5A) with scape and pedicel subcylindrical; flagellum with blunt spines laterally and trifid blunt setae dorsally. Labrum with dorsal surface near distolateral margin with two long and thin setae distinguishable from others; lateral margin with simple setae; distolateral and distal margins with bifid and pectinate setae. Right mandible with incisors cleft. Labium with glossa longer than paraglossa, broad basally, narrowing toward apical third; inner margin bare ventrally; inner margin dorsally with nine stout setae increasing in length apically; apex with one or two stout setae dorsally; outer margin ventrally bare; outer margin with five to six spine-like setae dorsally; ventral surface with few thin and simple setae, and one longitudinal row of thin and simple setae. Paraglossa apex rounded; apical half of outer margin ventrally with one row of five long stout setae; dorsally with row of 10 long, stout setae; dorsal surface with one longitudinal row of six to seven setae increasing in length apically; ventral surface with one row of thin and simple setae. Labial palp with segment I 1.0× length of segments II and III combined. Distomedial protuberance of segment II 2.0–2.3× width of base of segment III; inner margin with covered with short and simple setae; outer margin covered with short and simple setae; covered with simple setae dorsally. Inner margin of segment III with two stout setae; length 1.0× width; covered with short and simple setae. Thorax with foreleg ( Fig. 5B) whitish, femur tinged with light brown. Ratio of foreleg 1.4:(0.27mm):1.0:0.3. Forefemur with length about 3.4× maximum width; dorsal margin with row of blunt setae ( Fig. 5C) (in lateral view they look like stout setae); ventral margin with few short simple setae; length of setae on dorsal margin about 0.25× maximum width of femur; anterior surface with one row of blunt setae near ventral margin. Dorsal margin of tibia with short and simple setae; ventral margin with one row of stout setae; anterior surface bare. Dorsal margin of tarsus with scarce short and simple setae; ventral margin with one row of stout setae. Mid and hind legs similar to foreleg. Abdomen. Gills hyaline; margin with narrow spines intercalating short, thin and simple setae. Tracheae pigmented, restricted to main trunk. Gill I about 1/2 length of segment II; lanceolate. Gill IV as long as length of segment V to half VI combined; lanceolate. Gill VII as long as length of segments VIII to IX; lanceolate. Paraproct with 1 2–16 marginal spines; postero-lateral extension with marginal spines. Caudal filaments light brown. Paracercus ( Fig. 5F) with lateral spines on few segments. Cercus ( Figs 5D and 5E) with short spines on each segment, and long spines laterally.

Comments. See P. aristotelesi sp. n. for taxonomic comments about this nymph. The presence of a spine on the styliger plate is common in Paracloeodes species, but in P. atroari it is long, projected ventrally and, together with one rounded protuberance at the base of this spine, makes the male imago of P. atroari easily identifiable.

Nymphs are restricted to small gravel on a sandy bottom with some leaves, always in moderate flow.

Material examined. One nymph (Paratype), BRAZIL, Amazonas state, Presidente Figueiredo , Sossego da. Pantera , Km 20, 7.x.2003, 02°02’34” S / 59°51’08”W, F.F. Salles col., INPA . Two nymphs, BRAZIL, Amazonas state, Presidente Figueiredo, Sossego da. Pantera , Km 20, 14.xi.2009, P.V. Cruz and R. Boldrini cols., INPA. Seven nymphs and two male imagoes reared, BRAZIL, Amazonas state, São Gabriel da Cachoeira , BR 304, Km 19, 27.viii.2011, 00°02’58.4” S / 066°57’47.1” W, P. V. Cruz and A. S. Fernandes cols., INPA. Two nymphs, BRAZIL, Amapá, Serra do Navio , rio Cachaço , Cachoeira do Fernando , 00°53’18.8” N / 052°01’22.9”W, 61 m alt., 02.viii.2011, A.M. O. Pes, P.V. Cruz and A. S. Fernandes cols., CZNC; four nymphs, BRAZIL, Rondônia state, 26.viii.2012, Guajará Mirim, Rio Cotia , 09°46’01.3”S / 65°06’53.7”W, R. Boldrini and A. S. Fernandes cols., INPA.