Caenis sp. 2

Srinivasan, Pandiarajan, Sivaruban, T., Barathy, S. & Isack, Rajasekaran, 2023, Contribution to the knowledge of family Caenidae (Insecta: Ephemeroptera) from Madurai District, Tamil Nadu, Zootaxa 5258 (1), pp. 39-75 : 69-70

Caenis sp. 2

( Figs. 152–156 )

Materials examined. 5♀ imagoes, South India, Tamil Nadu, Madurai District, Karuppaurani lake , 9°94′07′′N, 78°18′84′′E, 132 m, 24.V.2020, colls. P. Srinivasan & R. Isack ( AMC /ZN/266) .

Description.

Female imago ( Fig. 152 ). Measurements. Body length: 2.7 mm; forewing length: 2.5 mm; foreleg length: 1.2 mm; midleg length: 1.2 mm; hindleg length: 1.1 mm; cercus length: 1.4 mm.

Coloration. Head: Vertex with dark brownish transverse markings between lateral ocelli. Antenna: scape and pedicel light brownish. Thorax: Prothorax darkened laterally. Mesonotum generally light brownish with two longitudinal bands in the sub medial area; scutellum pale; mesonotal suture darkly pigmented; prosternum, mesosternum, and metasternum pale yellowish. Wings hyaline, costa, and subcostal vein reddish-brown. Legs whitish, except apical part of femora and tibiae with a dark brownish patch. Abdomen: Terga I–IV with a welldeveloped black transverse band, terga IX–X mostly colourless. Cerci translucent.

Head. Fore margin between lateral and frontal ocelli slightly bowed. Pedicel two times the length of scape. Base of the antennal flagellum slightly dilated.

Thorax. Prosternal sclerites anteriorly converging, forming a broadly rounded triangle; transverse strip short.

Abdomen. Tergum II without a finger-like process. Lateral filaments short.

Male imago and larva. Unknown.

Egg. Length: 110–120 μm; width: 75–85 μm. Oval-shaped ( Figs. 153 ); chorion smooth with an epithemata of coiled-rope-type with numerous small terminal knobs on the pole ( Figs. 154, 155 ). Epithemata of a modified C. perpusilla subtype. Micropyle moderate, situated at the subequatorial plane with mouth not broadened, with well visible circular sperm guide ( Fig. 156 ).

Distribution. Karuppaurani lake, Madurai, Tamil Nadu, India.

Discussion. The unnamed species Caenis sp. 2 is similar to C. ulmeriana by the egg structure, however, it is distinguished by the smooth chorionic surface (Malzacher and Sangpradub 2020).

Figures

FIGURES 152–156. Caenis sp. 2: (152) female imago; (153) SEM view of egg; (154, 155) SEM view of epithema; (156) SEM view of micropyle.