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

publication ID 10.11646/zootaxa.4756.1.1

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Thraulodes nigrabdominalis

sp. n.

14. Thraulodes nigrabdominalis  sp. n.

( Figs 450–478View FIGURES 450–463View FIGURES 464–473View FIGURES 474–478)

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.GoogleMaps  Paratypes (presumably associated): the same locality, date and collector: 1 L ♂ (last instar), 3 L ♀ (penultimate instar), 1 larval exuviae (penultimate instar).GoogleMaps 


Larva (presumably associated). CUTICULAR COLORATION ( Figs 459–453, 456–458View FIGURES 450–463). 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, 459View FIGURES 450–463). Tergalii gray, tracheae black ( Figs 454–455View FIGURES 450–463).

SHAPE AND SETATION. Clypeus parallel-sided; labrum 1.3–1.4 times wider than clypeus ( Fig. 459View FIGURES 450–463). 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. 88View FIGURES 86–93), 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. 461View FIGURES 450–463). 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 462–463View FIGURES 450–463): 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 454–455View FIGURES 450–463): 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 460View FIGURES 450–463, 477–478View FIGURES 474–478): 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, 473View FIGURES 464–473, 475View FIGURES 474–478). 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. 464View FIGURES 464–473). On all legs femur light brown, bordered by darker brown on outer and inner margins and apically; tibia and tarsus light brown ( Fig. 470View FIGURES 464–473). Wings brown due to brown ring around base of each microtrichion; microtrichia blackish-brown (as in Fig. 438View FIGURES 427–438). 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. 473View FIGURES 464–473).

Male imago ( Figs 465–469View FIGURES 464–473). 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. 142View FIGURES 133–142). Pterostigmatic cross veins moderately dense, oblique, non-branched. Hind wing with brown macula on costal brace ( Fig. 476View FIGURES 474–478).

Abdominal hypodermal coloration: all terga and sterna uniformly brown ( Fig. 466View FIGURES 464–473). Caudalii brown, with joinings darkened.

Genitalia ( Figs 471–472View FIGURES 464–473, 474–475View FIGURES 474–478): 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. 477View FIGURES 474–478), which is the same as in imago and subimago of Th. nigrabdominalis  sp. n. ( Figs 474–475View FIGURES 474–478); this differs from the sympatric species of the same group, Th. nigripes  sp. n., whose styliger is wide-rectangular ( Fig. 499View FIGURES 498–507) and gets this shape at the same early stage of developnemt ( Fig. 502View FIGURES 498–507). In contrast to Th. niger  sp. n., larvae under consideration have no paired submedian hypodermal markings on the abdominal terga ( Fig. 459View FIGURES 450–463), the same as in the imago of Th. nigrabdominalis  sp. n. ( Fig. 466View FIGURES 464–473).

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  .