Caenis amacayacu, Lima, Lucas R. C., Molineri, Carlos, Pinheiro, Ulisses & Salles, Frederico F., 2016

Lima, Lucas R. C., Molineri, Carlos, Pinheiro, Ulisses & Salles, Frederico F., 2016, Two new species of Caenis Stephens, 1835 (Ephemeroptera: Caenidae) from South America, Zootaxa 4170 (1), pp. 114-124 : 116-117

Caenis amacayacu sp. nov.

( Figures 2–5 )

Diagnosis. This species is characterized by the following combination of characters. Male imago: 1) body length of male 2.8 mm; 2) base of antennal flagellum not dilated; 3) forceps pointed, sharpening abruptly and forming a long tip at the apex ( Fig. 4–5 ); 4) styliger plate as wide as long, with apex straight and two small lateral lobes posteriorly ( Fig. 4 ); 5) penes protruding dorsally and laterally, forming a wing-shaped structure ( Fig. 4 ).

Description. Male imago. Body length: 2.8 mm; forewing length: 2.2 mm; foreleg length: 2.3 mm; hind leg length: 1.2 mm; cercus length: 7.4 mm.

Ratios. Leg: body size 1.22 length of foreleg; foreleg 1.88 length of hind leg; 1st segment of foretarsus length: 2nd: 3rd: 4th: 5th = 1:5.3:2.6:2.1:1.6. Genitalia: styliger plate length 0.65 its width; forceps length 12.64 their width at distance from base; ratio of distance between extreme lateral points of forceps bases to distance of forceps length = 1.65.

Coloration. Head: whitish shaded with black dorsally, with pale line medially ( Fig. 3 ); venter of head yellowish. Antenna: scape and pedicel whitish, flagellum hyaline shaded with gray at base.

Thorax. Prothorax whitish washed with black dorsally; prosternum whitish. Meso- and metanotum light brown; pleurae and sterna lighter ( Fig. 2 ). Wing membrane hyaline; veins translucent except C, Sc and Rs grayish. Legs whitish, except femora and apical part of tibiae brownish, shaded with black; middle and hind tibiae with blackish marks on apical part of femora and base of tibiae.

Abdomen. Whitish with blackish bands dorsally, paler laterally. Terga I–II and VII–IX darker laterally. Sterna whitish, except IX–X blackish. Pleura with tracheae weakly pigmented.

Genitalia. Sternum IX with chitinous lateral structures strongly colored ( Fig. 4 ). Forceps dark brown. Penes whitish, with ventral V-shaped light brown mark. Caudal filaments whitish translucent.

Morphology. Antenna: Base of flagellum not dilated.

Thorax. Lateral margins almost straight, not protruding; prosternal longitudinal ridges forming broad triangleshaped structure, anteriorly truncate and laterally with concave margins ( Fig. 3 ).

Abdomen. Lateral filaments present on terga VIII–IX, very short; finger-like process on tergum II lacking.

Genitalia. Styliger plate rectangular with apex straight and two small lateral lobes posteriorly; central sclerite elongate dome shaped; apophyses short, triangular and pointed; lateral sclerites tape shaped, with broad base, more or less parallel, extended forward to central sclerite; basolateral sclerites divergent, laying distant from lateral sclerites ( Fig. 4 ). Forceps pointed, base not close to lateral margins of styliger plate, sharpening abruptly, forming long tip at apex. Ventral surface of penes with V-shaped sclerotized groove; penes lobes each with apical incision, dorsally and laterally protruding, forming dorsolateral wing-shaped structure ( Fig. 4 ).

Female imago and nymph. Unknown.

Etymology. The name, a noun in apposition, alludes to the type locality of Parque Nacional Amacayacu .

Type material. Holotype: male imago (genitalia on slide), Colombia, Departamento Amazonas, Parque Nacional Amacayacu , Quebrada Matamatá , S3°48’ 28, W70°15’ 21, 02.ii. 1999, Zuñiga, MdelC, Molineri, C, Domínguez, E. cols. (MUSENUV).

Figures

FIGURES 2 – 5. Male imago of Caenis amacayacu sp. nov.: 2) detail of prosternum; 3) dorsal view of head and thorax; 4) ventral view of genitalia; 5) detail of forceps.