Thraulodes nigrabdominalis, Kluge, Nikita J., 2020

Kluge, Nikita J., 2020, Systematic position of Thraulodes Ulmer 1920 (Ephemeroptera: Leptophlebiidae) and descriptions of new and little-known species, Zootaxa 4756 (1), pp. 1-142 : 104-107

14. Thraulodes nigrabdominalis sp. n.

( Figs 450–478 )

Etymology. Allusion to uniformly dark brown, nearly black color of abdomen of imago.

Material examined. Holotype: S-I ♂ {specimen [ XXXIII] (5) 2006} PPERU, Aquaytia, Pampa Yurac (9°04’S, 75°57’W), 23–25.II.2006, coll. N. Kluge. Paratypes (presumably associated): the same locality, date and collector: 1 L ♂ (last instar), 3 L ♀ (penultimate instar), 1 larval exuviae (penultimate instar).

Descriptions.

Larva (presumably associated). CUTICULAR COLORATION ( Figs 459–453, 456–458 ). Dorsal side of head, pronotum and mesonotum brownish, with lighter and darker areas. Abdominal terga I–II or I–III either light brown, or with light brown markings; terga III–VIII either uniformly light, nearly colorless, or tergum VII bordered by reddish-brown anteriorly; terga VIII–IX contrastingly colored by intensive reddish-brown; tergum X light, nearly colorless. Femora mostly light, fore femur with subapical brown band, middle and hind femora with basal and subapical brown bands. Tibia and tarsus uniformly light brownish.

HYPODERMAL COLORATION. Abdominal terga, besides peculiar cuticular coloration (see above) with narrow blackish lines bordering posterior margins of some terga ( Figs 453, 459 ). Tergalii gray, tracheae black ( Figs 454–455 ).

SHAPE AND SETATION. Clypeus parallel-sided; labrum 1.3–1.4 times wider than clypeus ( Fig. 459 ). Labrum widest at midlength; initial fore margin (turned ventrally) without median emargination, shallowly concave, with all 5 denticles wide; anterior transverse setal row regular (as in Fig. 88 ), as wide as all 5 denticles. Maxilla with 19 pectinate setae in apical-ventral row.

Femora: Stout setae on anterior surface narrowed distally and truncated ( Fig. 461 ). Irregular row of hairs near inner margin absent on fore and middle femora, sparse on hind femur.

Fore tibia: outer hairs form two irregular rows; inner-anterior row of recurved hairs absent; inner-anterior row of stout setae absent; inner field of stout pointed setae dense (i.e. setae longer than distances between them), consists of pointed bipectinate and smooth setae, situated irregularly (about 3–4 setae in cross section).

Hind tibia ( Figs 462–463 ): each of three rows of stout setae—outer-anterior, outer-posterior and inner-anterior ones—contains moderately long, narrowing distally stout setae with apices either blunt, or pointed; outer-anterior row, besides this, can contain long spoon-like setae; hairs located between outer-anterior and outer-posterior rows, form one irregular row (besides row of hairs posteriad of outer-posterior row of stout setae).

Claws with 2–4 denticles on rigid portion, with minute denticles on articulatory portion.

Tergalii ( Figs 454–455 ): wide; on both lamellae main trachea mainly with branches directed toward costal margin; dorsal lamella bent backward, with costal margin more convex than anal, widest in proximal or middle part, gradually narrowed toward apex, with slender apical filament; ventral lamella widest near base, gradually narrowed toward apex, with slender apical filament.

Male genitalia in last larval instar ( Figs 460 , 477–478 ): protogonostyli short and separated one from another by shallow concavity. Each protopenis lobe with extremely short projected gonopore-bearing process; gonopores opened caudally.

Subimago ( Figs 464, 470, 473 , 475 ). CUTICULAR COLORATION. Cuticle mostly brown. Mesonotum darker brown, with darker brown antelateroparapsidal and lateroparapsidal sutures, lighter oblique stripes on posterior scutal protuberances and colorless achromozones; medioscutal and submedioscutal chromozones equally colored by brown, separated by darker brown medioscutal suture ( Fig. 464 ). On all legs femur light brown, bordered by darker brown on outer and inner margins and apically; tibia and tarsus light brown ( Fig. 470 ). Wings brown due to brown ring around base of each microtrichion; microtrichia blackish-brown (as in Fig. 438 ). Abdominal terga, sterna, gonostyli and caudalii light brown.

TEXTURE. On tarsi of all legs, 1st tarsomere with microtrichia (as tibia), 2nd–5th tarsomeres coved by blunt microlepides; pointed microlepides present near apical margins of 2nd–4th tarsomeres of all legs ( Fig. 473 ).

Male imago ( Figs 465–469 ). Coloration of body and legs nearly uniformly dark brown. Head and antennae dark brown. Dorsal eyes contiguous medially, dull orange. Thorax dorsally, laterally and ventrally equally dark brown, with pleural membranes brownish ocher.

Cuticle of legs light brown; hypodermal pigmentation of femur, tibia and tarsus of all legs uniformly dark brown. In holotype,relation of fore femur to fore wing length 68:260; proportions femur/tibia/tarsomeres on fore leg 68:87:3:14:11:9:8; on middle leg 63:65:3:3:3:3:7; on hind leg 77:68:3:3:3:3:7.

Fore and hind wing with longitudinal and cross veins ocher. Costal cross veins proximad of bulla either absent, of few, colorless and very thin, so that visible only under high magnification (as in Fig. 142 ). Pterostigmatic cross veins moderately dense, oblique, non-branched. Hind wing with brown macula on costal brace ( Fig. 476 ).

Abdominal hypodermal coloration: all terga and sterna uniformly brown ( Fig. 466 ). Caudalii brown, with joinings darkened.

Genitalia ( Figs 471–472 , 474–475 ): Styliger, gonostyli and penis uniformly brown. Dorsal extension of styliger more or less prominent. Penis lobes long, narrow and slightly divergent; each penis lobe parallel-sided, without lateral pouch, not widened apically, without ear. Telopenes in form of spear-like rolls, attached at apices of penis lobes, directed caudally-medially, stout, with groove opened dorsally-laterally.

Female and eggs. Unknown.

Dimension. Fore wing length (and approximate body length) 6.5 mm.

Stage association. Winged stages were not reared from larvae, and subimaginal parts were not extracted from mature larva, so association of larva and winged stages is only presumed. This association is based on the following features.Last instar larva has tibia of hind leg tinged with blackish hypodermal pigment, that testifies about black tibia in winged stages and placing this species to the niger group. In contrast to other three species of this group, the imago of Th. nigrabdominalis sp. n. has no hypodermal pigmentation on area of costal brace of fore wing; this coloration, when present in winged stages, is expressed on the larval protopteron as well, being developed not only in last larval instar, as well in some of the previous instars; larvae under consideration lack this pigmentation, which testifies in favor of their belonging to Th. nigrabdominalis sp. n. In the examined male larva of last instar, the styliger, being at a very early stage of its development, already has a narrow-parabolic shape ( Fig. 477 ), which is the same as in imago and subimago of Th. nigrabdominalis sp. n. ( Figs 474–475 ); this differs from the sympatric species of the same group, Th. nigripes sp. n., whose styliger is wide-rectangular ( Fig. 499 ) and gets this shape at the same early stage of developnemt ( Fig. 502 ). In contrast to Th. niger sp. n., larvae under consideration have no paired submedian hypodermal markings on the abdominal terga ( Fig. 459 ), the same as in the imago of Th. nigrabdominalis sp. n. ( Fig. 466 ).

Comparison. The male imago and subimago of Th. nigrabdominalis sp. n. are similar to Th. niger sp. n.; the male imago differs from Th. niger sp. n. by an absence of coloration of costal and subcostal fields of the fore wing and by absence of paired dark markings on the abdominal terga. Both Th. nigrabdominalis sp. n. and Th. niger sp. n. have penis structure similar to that of Th. ephippiatus Traver & Edmunds 1967 , Th. cochunaensis Domínguez 1987 and Th. basimaculatus Giordano & Domínguez 2005 and differ from these three species by uniformly dark brown femora and tibiae of all legs. Larval cuticular coloration distinguishes this species from all other known species of Thraulodes .

Figures

FIGURES 450–463. Larvae, presumably attributed to Thraulodes nigrabdominalis sp. n. 450–455, parts of last instar larva at the same magnification: 450, fragment of head with labrum and mandibles; 451, pronotum and mesonotum; 452, hind leg; 453, abdominal terga; 454–455, tergalii IV–V; 456–458, exuviae of young larva at the same magnification: 456–457, fore and hind legs; 458, abdominal terga and sterna; 459, young larva with brown cuticular coloration and blackish hypodermal coloration; 460, larval protogonostyli and protopenis; 461, anterior side of hind femur; 462, hind tibia with focus on outer-posterior row of stout setae; 463, the same with focus on outer-anterior and inner-anterior rows of stout setae.

FIGURES 464–473. Thraulodes nigrabdominalis sp. n. (holotype). 464, left half of subimaginal exuviae of mesonotum; 465, 466, male imago; 467–469, fore, middle and hind legs of male imago; 470, subimaginal exuviae of fore leg; 471, genitalia of male imago; 472, apex of penis; 473, subimaginal exuviae of tarsus.

FIGURES 474–478. Thraulodes nigrabdominalis sp. n. 474, genitalia of male imago in ventral view; 475, their subimaginal exuviae; 476, hind wing; 477–478, protogonostyli and protopenis of presumably associated larva, with subimaginal gonostyli and styliger at early stage of development shown by interrupted line (474–476, holotype).

FIGURES 86–93. Thraulodes telegraphicus. 86, median longitudinal section of labrum in usual condition; 87, the same, in spread condition; 88, labrum in spread condition in dorsal view (setal rows shown as dotted lines); 89, transverse section of hind tibia; 90–93, tergalii I, III, VI and VII. Abbreviations: anter.r, anterior transverse row of setae; dent., five denticles separated by six sensilla; poster.r, posterior transverse row of setae; i.f, inner field of stout pointed setae; i-a.h, inner-anterior recurved hairs; i-a.r, inner-anterior row of stout setae; o-a.r, outer-anterior row of stout setae; o.h, outer hairs; o-p.r, outer-posterior row of stout setae; p.r, row of posterior pointed pectinate setae.

FIGURES 427–438. Thraulodes niger sp. n. 427–428, head and thorax of male imago in lateral and dorsal view; 429, abdominal terga and sterna of male imago; 430, the same of male subimago; 431, subimaginal mesonotum; 432–433, genitalia of male imago with focus on styliger and on penis; 434, female imago; 435, its left fore wing; 436–437, its fore and middle legs; 438, subimaginal exuviae of fore wing (427–429, 432–433, 438, holotype).

FIGURES 133–142. Thraulodes panamensis sp. n. 133, pterostigma; 134–136, male imago in lateral in ventral and dorsal view; 137–138, left half of subimaginal exuviae of mesonotum of two different specimens; 139, female imago; 140–141, genitalia in lateral and ventral view; 142, costal margin of fore wing (arrows show proximal costal cross veins) (133, 134, 136, 137, 141, 142, holotype).

FIGURES 498–507. Thraulodes nigripes sp. n. 498, larval protogonostyli and protopenis; 499, subimaginal styliger and gonostyli extracted from larva; 500–501, subimaginal penis inside larval protopenis in ventral and dorsal view; 502, larval protogonostyli with subimaginal gonostyli and styliger at earlier stage of development; 503–506, tergalii I, III, VI and VII (498–501, 503–506, holotype).