Mayfly Species Paraleptophlebia falcula

This is another bi-colored, white-winged, pale-legged species with a pair of dark spots on the dorsum of the 2nd abdominal segment. Head, thorax, and end segments of the abdomen reddish brown above; paler beneath. Legs pale with brown knees. Wings white, hyaline, with only a touch of brown on the root of the radial vein and no darkening of the stigmatic area. Costal cross veins obsolete, extremely pale even in the stigmatic area where they are few and straight and simple; in the succeeding subcostal space they are obsolete and there is no touch of milky whiteness in the stigmatic area.

Abdomen brown on the end segments, paler beneath and at the tip; segments 3 to 6 whitish; 2 and 7 less so. There is a pair of round brown spots on the dorsum of 2, and segment 7 is covered above by a broad triangular cloud. A faint touch of brown lies like a shadow across the middle of the intervening white segments. Spiracles marked with distinct black dots. The apices of the triangular divisions of the 9th sternite are very peculiar; they are prolonged in linear strap-like form that attains the farthest level of the penial notch. Basal segment of forceps white, widened in the middle and tapering near the tip. Penes separated by an open U-shaped cleft a little deeper than wide; each terminates in a flat, triangular process. The reflexed spurs are sickle-shaped, at first bending inward until the two almost touch, then widely outcurving to the side (see fig. 134). Tails white.

Source: Redescription of Paraleptophlebia falcula Traver 1934 with notes on status and composition of Paraleptophlebia Lestage 1917 and Neoleptophlebia Kluge 1997 (Ephemeroptera: Leptophlebiidae)

Description. Mature larva. Length (mm): body 5.3 – 6.8; cerci 4.6 – 8.2. Head: Brown with occipit light brown and pale spots around lateral ocelli and anterior to median ocellus (cuticular coloration). Antennae white. Labrum dark brown; dorsal surface covered with long hair-like setae; anterior margin with shallow emargination and several rows of stout setae (Fig. 1). Mandibles dark brown, with broad band extending parallel to outer edge (Figs 2 – 3). Left mandible with incisor terminated by 4 denticles and kinetodontium terminated by 3 denticles (Fig. 4), right mandible with incisor terminated by 3 denticles and kinetodontium terminated by 3 denticles (Fig. 5). Both mandibles with extensive patches of setae on dorsal surface in middle area. Right mandible with row of long hair-like setae proximal of molar surface (Fig. 3). 1 st segment of maxillary palp with several spine-like setae along outer margin and small thin setae along inner margin; 2 nd segment with long hair-like setae on both margins; 3 rd segment almost completely covered with very long, thin hair-like setae (Fig. 6). Maxillary palp with 2 nd and 3 rd segments subequal in length, together 1.5 times longer than 1 st segment. Labium as in Fig. 7; apical part of dorsal surface of glossae densely covered with stout hair-like setae; among them small stout setae located nearer to inner edge; dorsal surface of paraglossae covered with small stout setae and long hair-like lateral setae (Fig. 7); 3 rd segment of labial palp with rows of stout variably spaced setae (Fig. 8). Labial palp with 2 nd segment shorter than 3 rd segment, 2 nd and 3 rd segments together longer than 1 st segment. Hypopharynx slightly emarginated apically (Fig. 9). Thorax: Pronotum brown with white lateral margins and wide pale stripe along posterior margin; mesonotum brown with diffuse pale spots anteriorly and between protoptera (cuticular coloration) (Fig. 14). Legs grayish. Forefemora with row of stout setae on inner edge; anterior side of forefemora covered with stout setae of identical form and size (Fig. 10). Claw with single row of denticles, reaching middle of claw; apex of claw elongate (Fig. 11). Ratio of length femur / tibia and tibia / tarsus: fore and middle legs 1.3 – 1.2 and 1.4 – 1.5; hind leg 1.4 – 1.2 and 1.4 – 1.7. Abdomen: Terga brown with light spots; lateral edges pale; terga II – III with small triangular light spot on median part of posterior margin; terga IV – VI with a toothed light spot occupying about half of tergum length, on terga VII – IX reaching anterior margin; tergum X light with brown lateral edges (cuticular coloration) (Fig. 14). Abdominal terga III – IX with regular row of triangular stout spines on posterior margin and irregular rows of small spines anteriad of it (Fig. 12). Posterolateral spines on abdominal segment IX longer than on segment VIII. Abdominal sterna light brown with brown band on anterior margin, lateral edges pale; sterna VIII – IX pale, yellowish; sternum X pale, yellowish with brown lateral angles (cuticular coloration) (Fig. 15). Sterna I – VII with ganglion spots. Sternum IX of female with postero-median emargination (Fig. 13). All tergalii hairy (Figs 16 – 22); hairs very thin, pale, and break off easily; well visible only on a dark background. Cerci pale, grayish, darker at base.

Male imago (in alcohol). Length (mm): body 6.0 – 8.5; forewings 6.8 – 8.5; cerci 7.7 – 9.5. Head: General color dark brown to dark. Antennae brown; ocelli whitish apically and black basally. Upper portion of compound eyes light brown to yellowish or grayish-brown; low portion dark (Figs 23 – 24); compound eyes contiguous (Fig. 24). Thorax: General color dark brown. Medioscutum and submedioscutum dark brown (Fig. 24); posterior scutal protuberance dark with small light spot on lateral sides; sublateroscutum brown to light brown. Wings pale, hyaline; all veins pale, almost invisible; veins C and Sc slightly darker and visible; pterostigma milky (Fig. 23). Femora and tibia of forelegs whitish or yellowish, joints brown; tarsal segments pale or whitish. Middle and hind legs grayish, femur slightly darker. Ratio of length of femur / tibia 0.8 – 0.9; ratio of tarsal segments length 0.95: 1.5: 2.8: 3.3. Abdomen: Terga with contrasting pattern (Fig. 24): tergum I dark brown; tergum II light brown or brownish; terga III – VI dirty yellowish, translucent, posterior margins darker; lateral sides with dark tracheal trunk; tergum VII dirty brownish with pair of darker stripes in middle area, with posterior margin dark brown; terga VIII – IX dark. Abdominal sterna with contrasting pattern: sternum I dark brown; sternum II brownish; sterna II – VI yellowish, translucent; sternum VIII dirty gray or dark brown; sternum IX dark brown with light central area. Nerve ganglia brown, visible on segments II – VII (Fig. 25). Cerci white. Genitalia: Styliger brown, somewhat lighter in posterior area, gonostyli yellowish. Styliger deeply concave medially, with U-shaped incision and two long slightly curved processes reaching bases of ventral processes of penis (Figs 26, 29, 30). Gonostylus with 1 st + 2 nd segment widest at middle, bent ventrally near base; 3 rd segment slightly widened apically; 4 th segment smallest (Fig. 26). Penis lobes separated by U-shaped cleft reaching middle of penis length; each penis lobe with triangular widening, with apex pointed and curved inwards, ventrally with long crescent-shaped pointed process directed proximally and reaching proximal 1 / 3 of penis (Figs 27, 30).

Female imago (in alcohol). Length (mm): body 7.3 – 8.1; forewing 8.0 – 9.0; cerci 7.5 – 8.5. Head: General color dark brown. Antennae brown; ocelli whitish apically, black basally. Thorax: General color dark brown (Fig. 31). Medioscutum and submedioscutum from brown; posterior scutal protuberance dark; sublateroscutum brown with white maculation; scuto-scutellar impression dirty brownish or dirty whitish. Wings pale, hyaline; longitudinal veins of forewing light brown, visible; hind wing colorless; all cross veins colorless, poorly visible. Legs light brown, femur slightly darker. Ratio of length femur / tibia and tibia / tarsus on forelegs 1.0 – 0.9 and 1.3 – 1.4. Abdomen: Terga and sterna dark brown (Fig. 31). Subanal plate with deep V-shaped incision (Fig. 32). Cerci yellowish or whitish.

Eggs. General form oval 190 – 214 µm length and 85 – 118 µm width (Fig. 33). Chorion rugose, with broad and deep folds (Fig. 34), with small flower-shape KCT sparsely arranged (Figs 33, 35). Two or three small round micropyles in middle area (Fig. 33). Sperm guide absent (Figs 36 – 37).