Callibaetis (Cunhaporanga) imperator, Cruz, Paulo Vilela, Salles, Frederico Falcão & Hamada, Neusa, 2017

Cruz, Paulo Vilela, Salles, Frederico Falcão & Hamada, Neusa, 2017, Four new species of Callibaetis Eaton (Ephemeroptera: Baetidae), nymphal description of Callibaetis (Abaetetuba) fasciatus (Pictet) and keys for South American species of Callibaetis, Zootaxa 4250 (3), pp. 229-261 : 251-258

Callibaetis (Cunhaporanga) imperator sp. nov.

( Figs 17–20 )

Callibaetis sp. C: Cruz et al. 2016

Known stages. male and female imagoes, nymph

Diagnoses. Male imago: 1) dorsal portion of turbinate eyes oval ( Fig. 17 A); 2) turbinate eyes with constriction (in lateral view) ( Fig. 17 B); 3) turbinate portion of compound eyes (in lateral view) with divergent anterior and posterior margins ( Fig. 17 B); 4) anterior and posterior margins of forewing with pigmentation ( Fig. 17 G); 5) marginal intercalary veins paired ( Fig. 17 G); 6) hind wing with large brown mark ( Fig. 17 H); 7) costal process of hind wing pointed; 8) marginal intercalary veins on hind wing absent ( Fig. 17 H); 9) abdominal terga III and V with lateral red marks ( Fig. 17 A); 10) abdominal sterna covered with brown spots ( Fig. 17 C); 11) abdominal terga and sterna with strongly pigmented medioanterior and medioposterior sigilla; 12) forceps segment I wide at base ( Fig. 17 K); 13) segment III of forceps rounded ( Fig. 17 K).

Female imago: 1) anterior and posterior margins of forewing with pigmentation ( Fig. 17 I); 2) marginal intercalary veins paired ( Fig. 17 I); 3) hind wing with large brown mark ( Fig. 17 J); 4) hind wing with a pointed costal process ( Fig. 17 J); 5) marginal intercalary vein on hind wing present ( Fig. 17 J); 6) abdominal terga and sterna with strongly pigmented medioanterior and medioposterior sigilla ( Figs 17 D and 17F); 7) abdominal sterna covered with brown spots ( Fig. 17 F).

Mature nymph: 1) distal margin of labrum with pectinate and stout setae medially ( Fig. 18 B); 2) maxillary palp 1.2× length of galea-lacinia; 3) complete row of setae on outer margin of maxilla ( Fig. 18 E); 4) paraglossae without tufts of thin setae ( Fig. 18 G); 5) ventral surface of paraglossae without a row of stout setae ( Fig. 18 G); 6) metanotum without spines; 7) anterior surface of foretarsus with pectinate stout setae ( Fig. 19 A).

Description. Male Imago. Length: body, 3.2 mm; forewing, 3.1 mm; hind wing, 0.5 mm (n=2). Head brown. Turbinate portion of compound eyes brown dorsally, stalk light brown ( Fig. 17 A). Antenna with scape and pedicel brown apically, flagellum white. Dorsal portion of turbinate eyes oval ( Fig. 17 A), dorsal portion of turbinate eyes, in lateral view, with constriction, and with anterior and posterior margins divergent ( Fig. 17 B). Thorax with anteronotal protuberance brown medially, posterior scutal protuberance white. Anteronotal and metascutellar protuberance rounded. Femora with few brown spots on anterior surface, tibiae with basal, medial and apical brown marks. Forewing with pigment concentrated in anterior and posterior margins ( Fig. 17 G); veins light brown; stigmatic area with six cross veins reaching the subcostal vein; marginal intercalary veins paired; length of each intercalary vein 0.5× distance between adjacent longitudinal veins; length of forewing about 2.5× its width. Hind wing with large brown mark ( Fig. 17 H); eleven cross veins; costal process pointed; marginal intercalary veins absent. Abdomen with terga III and V with lateral red marks; terga II to VII with large medioanterior sigilla; terga VIII and IX dark brown ( Fig. 17 A). Sterna covered with brown spots, medioanterior and medioposterior sigilla strongly pigmented ( Fig. 17 C). Segment I of forceps ( Fig. 17 K) wide at base; 0.35× length of segment II; distance between base of forceps 0.2× distance between lateral margins of forceps. Segment III of forceps with rounded apex, length 1.6× width; 0.14× length of segment II. Posterior margin of styliger plate with small rounded medial projection. Cerci with base and apex of each segment dark brown.

Female imago. Length: body, 3.6 mm; forewing, 3.9 mm; hind wing, 0.6 mm (n=2). Head ( Fig. 17 D) brown, with two brown marks. Antenna with scape and pedicel brown apically. Thorax ( Figs 17 D and 17E) with anteronotal protuberance light brown; posterior scutal protuberance brown. Anteronotal and metascutellar protuberance rounded. Femora with brown spots on anterior surface; tibiae with basal, medial and apical brown marks. Forewing ( Fig. 17 I) with pigment concentrated on anterior and posterior margins; stigmatic area with five cross veins reaching the subcostal vein; marginal intercalary veins paired; length of each intercalary vein 0.3× distance between adjacent longitudinal veins; length of forewing about 2.5× its width. Hind wing ( Fig. 17 J) with large brown mark; costal process pointed; marginal intercalary vein present. Abdomen with terga II to VII with large medioanterior sigilla, terga VIII and IX dark brown ( Fig. 17 D). Sterna covered with brown spots, medioanterior and medioposterior sigilla strongly pigmented ( Fig. 17 F). Cerci with base and apex of each segment dark brown.

Mature nymph. Length: body, 3.4 mm (n=2). Head with turbinate portion of male compound eyes brown. Antenna with spines and thin setae on flagellum ( Fig. 18 A). Labrum ( Fig. 18 B) maximum length about 1.2× minimum length; distal margin with V-shaped medial emargination; anterolateral margins with long and stout setae; distal margin with pectinate and stout setae medially; dorsal surface with numerous long and thin setae; ventral surface with short and stout setae near lateral margin; ventral surface with tuft of long and stout setae on anterolateral margin; ventral surface with one row of stout setae on distal margin. Right mandible ( Fig. 18 C) with 4+3 denticles; margin between prostheca and mola convex; basal half with short and thin setae, and pores scattered over dorsal surface. Left mandible ( Fig. 18 D) with 4+4 denticles; margin between prostheca and mola straight; basal half with short and thin setae and pores scattered over dorsal surface. Lingua of hypopharynx ( Fig. 18 F) with apical lobe covered with small simple setae; short and simple setae scattered over inner margin of superlingua. Maxilla ( Fig. 18 E) with complete row of stout setae on outer margin; medially, on inner margin, with 1+3 stout setae. Maxillary palp 1.2× length of galea-lacinia; palp segment II 0.7× length of segment I; outer margin of segment I covered with long and thin setae; inner margin of segment I with two rows of short and stout setae; outer margin of segment I with one row of short and stout setae; inner margin of segment II with one row of stout setae. Labium ( Fig. 18 G) with glossae and paraglossae similar in length; inner margin of glossae with ca. 21 stout setae; outer margin with one row of long and stout setae; dorsal surface with one row of long and stout setae near outer margin and one tuft of long and stout setae medially. Dorsal surface of paraglossae with one longitudinal row of long and stout setae near inner margin, two longitudinal rows of long and stout setae at middle, and one row of long and stout setae on outer margin; ventral surface without one row of stout setae. Labial palp with segment I as long as segments II and III combined; outer and inner margins of segment I with one row of setae; inner margin of segment II with ca. 11 stout setae, outer margin of segment II with three short and stout setae, and few long and thin setae; segment III subconical, whole margin of segment III with long and stout setae. Thorax brown. Metanotum without spines. Foreleg ratio ( Fig. 19 A) 1.5:(0.4 mm):0.78:0.3. Forefemur length about 5.4× maximum width; dorsal margin with row of stout setae; length of setae on dorsal margin about 0.16× maximum width of femur; ventral margin with one row of stout setae; anterior surface with one row of stout setae near dorsal margin; anterior surface with one row of stout setae near ventral margin. Ventral margin of tibia with one row of stout setae; anterior surface with stout setae. Ventral margin of tarsus with one row of stout setae; anterior surface of foretarsus with pectinate stout setae. Claw 0.4× length of tarsus. Mid and hind legs similar to foreleg, except for smaller denticles on claw ( Fig. 19 C). Abdomen ( Fig. 20 A) light brown. Posterior margin of terga with regular spines ( Fig. 20 B); terga III, V and VII dark laterally ( Fig. 20 A). Surface of sterna with thin setae. Gill I about equal to length of segment II, with three folds. Gill IV equal to length of segment V and half of segment VI combined, with two folds. Gill VII equal to length of segment VIII and half of segment IX combined, with one fold. Paraproct ( Fig. 20 C) with ca. 33 marginal spines. Paracercus and cerci with long spines every four segments.

Comments. The nymph of C. (Cunhaporanga) imperator sp. nov. is similar to the nymphs of C. (Cunhaporanga) gelidus Cruz, Salles & Hamada and C. (Cunhaporanga) nigracyclus Cruz, Salles & Hamada ; and can be distinguished by the presence of a complete row of setae on outer margin of maxilla in C. (Cunhaporanga) imperator sp. nov., while in C. (Cunhaporanga) gelidus and C. (Cunhaporanga) nigracyclus the row is incomplete.

Etymology. We are honoured in naming this species after Dom Pedro II, the last emperor of Brazil. Dom Pedro II was internationally recognized by many scientists, including Charles Darwin, as a man committed to science and education. In 1881, he visited one of the paratype locality, Santuário do Caraça, a prominent Brazilian school by that time.

Material examined. Holotype: Female imago with nymphal and subimaginal exuviae (reared), BRAZIL, Minas Gerais, Conceição do Mato Dentro , Rio Peixe Tolo , 19°00’14.40”S / 43°36’45.00”W, 08.ix.2012, F. F. Salles coll., CZNC . Paratypes: Two male and one female imagoes, BRAZIL, Minas Gerais, Santuário do Caraça, Catas Altas , 18.v.2006, N. Hamada coll., INPA ; two male imagoes, BRAZIL, Minas Gerais, Serra do Caraça, Sede do Santuário , 18.ix.2012, F. F. Salles coll., INPA ; one female imago; one female subimago with nymphal exuviae (reared), one female imago, one male imago with nymphal and subimaginal exuviae (reared), three nymphs, BRAZIL, Minas Gerais, Conceição do Mato Dentro, Rio Peixe Tolo , 19°00’14.40”S / 43°36’45.00”W, 08.ix.2012, F. F. Salles coll., CZNC .

Distribution. Brazil: Minas Gerais.

Keys. As species of Callibaetis cannot be placed in any subgenera without knowledge on the nymphs, due the lack of synapomorphies ( Cruz et al. 2016), keys for male and female imagoes follow the classic pattern. Given the recent improvement in taxonomic resolution, we propose a more practical and reliable keys to South American species. However, for a proper identification, we strongly recommend the use of two life stages (imago and nymph), and imagoes should be obtained rearing nymphs.

Figures

FIGURE 17. Callibaetis (Cunhaporanga) imperator sp. nov. imagoes. A. dorsal view of male; B. lateral view of male; C. ventral view of male; D. dorsal view of female; E. lateral view of female; F. ventral view of female; G. forewing of male; H. hind wing of male; I. forewing of female; J. hind wing of female; K. genitalia. Black arrow: marginal intercalary vein.

FIGURE 18. Callibaetis (Cunhaporanga) imperator sp. nov. nymph. A. antenna; B. labrum (left v. v., right d. v.); C. right mandible; D. left mandible; E. maxilla; F. hypopharynx; G. labium (left v. v., right d. v.).

FIGURE 19. Callibaetis (Cunhaporanga) imperator sp. nov. nymph. A. foreleg; B. detail of foreclaw; C. detail of hind claw.

FIGURE 20. Callibaetis (Cunhaporanga) imperator sp. nov. nymph. A. dorsal view of exuviae; B. posterior margin of terga IV; C. paraproct; D. cercus; E. paracercus.