Mayfly Species Thraulodes spangleri

Source: Systematic position of Thraulodes Ulmer 1920 (Ephemeroptera: Leptophlebiidae) and descriptions of new and little-known species

Descriptions. Larva. CUTICULAR COLORATION (Figs 379 – 483). Dorsal side of head, thorax and abdomen mostly brown with few blanks: pronotum bordered by light laterally; abdominal terga with blanks on lateral parts, area mediad of tergalii attachments nearly unicolor brown, terga VIII – IX with diffusive blank medially. Femora mostly brown, with blanks; tibiae and tarsi uniformly light brown. HYPODERMAL COLORATION. Abdominal hypodermal coloration unknown. Tergalii yellowish with gray, tracheae black (Fig. 385). SHAPE AND SETATION. Clypeus parallel-sided; labrum 1.2 – 1.3 times wider than clypeus (Fig. 389). Labrum widest at midlength, with narrow median emargination exposed ventrally; if all 5 denticles present, bottom of median emargination formed by 3 narrower denticles and its sides formed by 2 wide denticles (Fig. 390 – 391) (some denticles can be fused); anterior transverse setal row wider than all 5 denticles, in its median part represents field of irregularly situated setae (Figs 393 – 394). Maxilla with 17 pectinate setae in apical-ventral row. Femora: Stout setae on anterior surface narrowed distally or parallel-sided, apically blunt (Fig. 387). Irregular row of hairs near inner margin absent on fore femur, present on middle and hind femora. Fore tibia (Fig. 386): outer hairs form two irregular rows; inner-anterior row of recurved hairs absent; inner-anterior row of stout setae represented by few (2 – 3) stout setae near tibia base; inner field of stout pointed setae, consists of 2 well-distinguishable rows: one regular anterior row formed by short, curved, tridentate or bidentate (i. e. vestigial bipectinate) pointed stout setae, and one regular posterior row formed by long, straight, non-pectinate, pointed stout setae. Hind tibia (Fig. 388): outer-anterior and outer-posterior rows of stout setae consist of narrowed distally, blunt stout setae of various lengths and long spoon-like setae; hairs located between these rows, numerous and form more than one row (besides row of hairs posterad of outer-posterior row of stout setae); stout setae of inner-anterior row of various lengths, narrowed distally and blunt. Claws with 6 – 8 denticles on rigid portion, with or without minute denticles on articulatory portion. Tergalii (Fig. 385): each lamella slender, tracheae without side branches. Male genitalia in last larval instar (Fig. 407): protogonostyli moderately long and separated one from another by emargination with convex setose bottom. Each protopenis lobe smoothly stretched to gonopore-bearing process located near median margin; gonopores opened caudally.

Subimago (Figs 384, 386 – 387, 406). CUTICULAR COLORATION. Cuticle with colorless, light brownish and dark brown areas. Pronotum medially colorless, lateral areas diffusively shed by light brown. Mesonotum with diffusively outlined light brown macula occupying median part of anteronotal protuberance and anteronotal transverse impression; antelateroparapsidal and lateroparapsidal sutures dark brown either entirely (Fig. 396), or partly (Fig. 397); posterior part of lateroscutum and median part of posterior scutal protuberance brown; chromozones either colorless (Figs 397), or chromozone of medioscutum colored as a light brownish stripe separated from brown light macula on anteronotal transverse impression (Fig. 396). Thoracic pleura and sterna mostly colorless. On fore leg femur partly colorless, on outer and inner margins brownish, with narrow dark brown band at apex; tibia brown, darker brown proximally and distally; tarsus brown. Middle and hind legs lighter, without dark brown band on apex of femur, with tibia uniformly light brown. Cuticle of wings colorless, microtrichia light brownish. Abdominal terga light brownish with composite maculation; sterna colorless; gonostyli and caudalii light brown. TEXTURE. On tarsi of all legs, 1 st tarsomere with microtrichia (as tibia), 2 nd – 5 th tarsomeres coved by blunt microlepides; pointed microlepides present near apical margins of 2 nd – 4 th tarsomeres of middle and hind legs (as in Fig. 473).

Male imago (Figs 398 – 400). Anterior part of head (bearing antennae) whitish, posterior part (bearing ocelli) brown with ocher. Antenna ocher, pedicellus either orange, or with apex brown. Dorsal eyes contiguous medially, dull orange. Pronotum ocher with blackish-brown median stripe and brown lateral areas. Mesonotum and metanotum ocher with brown. Thoracic pleura ocher with interrupted blackish-brown stripe above coxa. Mesothoracic basisternum ocher; episterna and furcasternal protuberances from orange to brown; furcasternal median impression ocher, with peculiar round dark brown spot (Fig. 400). Cuticle of legs mostly colorless; on fore leg apex of femur and base of tibia with cuticle light brown. Legs with following hypodermal pigmentation on whitish background. Fore femur: middle 1 / 3 on anterior-inner side orange with blackish-brown; middle 1 / 3 on posterior side occupied by blackish-brown spot; distal 1 / 3 on both sides occupied by orange band; on posterior side apical orange band separated from middle brown spot by oblique non-pigmented stripe; inner margin of femur at distal 2 / 3 blackish-brown. Fore tibia apically blackish-brown; tarsus with last segment apically brown. Middle and hind femur with irregular, diffusive gray-brown spot in middle part and multicolored pre-apical band located within apical 0.4 of femur; pre-apical band mainly orange-brown, proximally with blackish-brown, on inner side with blackish-brown longitudinal stripes; apical 0.1 of femur non-pigmented. In selected individual, relation of fore femur to fore wing length 65: 280; proportions femur / tibia / tarsomeres on fore leg 65: 97: 3: 18: 15: 11: 9; on middle leg 63: 70: 3: 3: 3: 2: 8; on hind leg 75: 75: 3: 3: 3: 2: 8. Fore wing with well developed costal cross veins proximad of bulla; pterostigmatic cross veins moderately dense, either simple, or partly anastomosed (Fig. 398). Longitudinal veins light ocher, cross veins brown; dark brown macula on crossing of costal brace and Sc; cross veins of anterior-proximal area of wing (including proximal costals) bordered by brown. Hind wing with all veins light ocher, without coloration (even costal brace non-colored), with prominent costal projection (Fig. 408). Coloration of fore wing partly appear during larval development, being in subimago less contrasting than in imago. Abdominal hypodermal coloration: Tergum I brown. Terga II – VI light ocher, translucent, with pair of wide brown oblique lateral stripes widest on tergum II and narrowest on tergum VI; pleura with small brown stigmatic dots. Terga VII – X orange with whitish median stripe; tergum VII with whitish poster-lateral areas; tergum VIII with whitish lateral and posterior areas connected with whitish median stripe. Sterna I – IX ocher. Caudalii whitish, with black spots on each joining; in proximal part of caudalius each 2 nd joining with enlarged black spot, in distal part of caudalius each 4 th joining with enlarged black spot. Genitalia (Figs 402 – 406): Styliger light ocher; gonostyli mostly light ocher, preapical segment brown. Dorsal extension of styliger long and parallel-sided. Penis lobes sharply widened and divergent apically, with prominent lateral pouches. Apico-lateral area forming ear, projected laterally. Telopenes in form of spear-like rolls, attached on dorsal side and directed medially-dorsally, nearly straight, with groove opened dorsally-laterally (Figs 403, 405).

Female imago (Fig. 401). Abdominal terga II – VI brownish with ocher; in other respects coloration similar to that of male.

Eggs (Figs 409 – 410). Mostly barrel-shaped. Each KTC surrounded by wide, smooth ring-like cover. Large and small protuberances densely located close to these rings and less densely on other chorion. Dimension. Fore wing length (and approximate body length) 6 – 7 mm.