Thraulodes lepidus ( Eaton 1884 )

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 : 127-131

18. Thraulodes lepidus ( Eaton 1884)

( Figs 591–612 )

Thraulus lepidus Eaton 1884: 109 (♂ imago); Eaton 1892: 8 (subimago, ♂ and ♀ imago).

Thraulodes lepidus: Ulmer 1920: 34 ; Kimmins 1934: 343, fig. 7 (genitalia of ♂ imago); Kimmins 1960: 303 (holotype in British Museum); Traver & Edmunds 1967: 369, figs 18, 19, 27, 58 (♂ and ♀ imago).

? Thraulodes lepida: Ulmer 1943: 22 (♂ imago).

≠ Thraulodes pedregoso Traver 1946: 430 , figs 17–19 (synonymized by Traver & Edmunds 1967).

≠ Th. cryptodrylus Nieto & Dominguez 2001: 63 , figs 1–8 (synonymized by Mariano, Flowers & Froehlich 2011).

Material examined. PANAMA, Provincia de Bocas del Toro, bosque protector Palo Seco: Altos del Valle , Rio Buris (8°47’37’’N, 82°11’35’’W), 24–28.I.2018, coll. N. Kluge, L. Sheyko: 1 L /S ♂, 1 L ♀.

Descriptions.

Larva. CUTICULAR COLORATION ( Figs 592–596 ). Dorsal side of head, thorax and abdomen light ocher with brown maculae; among them, submedian pair of large brown maculae on terga VI–VII ( Fig. 595 ) or on terga II–VII ( Fig. 603 ). Legs nearly unicolor light ocher.

HYPODERMAL COLORATION ( Figs 591 , 603 ). Pronotum with paired blackish stripe, running parallel to lateral margin and parallel to lateral 2/3 of fore margin; mesonotum with blackish markings. Abdominal terga, besides peculiar cuticular coloration (see above) with blackish stripes bordering posterior margins of terga and with paired triangular lateral blackish spots corresponding to dark brown marking of imago. Tergalii yellowish with gray maculation ( Fig. 608 ).

SHAPE AND SETATION. Clypeus slightly widened distally; labrum 1.15–1.25 times wider than clypeus ( Fig. 592 ). Labrum widest at 0.4 length from base, with lateral sides angulate; fore margin (often turned ventrally), without median emargination, with all 5 denticles wide; anterior transverse setal row regular (as in Fig. 88 ), as wide as all 5 denticles. Maxilla with 23–24 pectinate setae in apical-ventral row.

Femora: Stout setae on anterior surface pointed ( Fig. 600 ). Irregular row of hairs near inner margin absent on fore femur, present on middle and hind femora.

Fore tibia ( Fig. 599 ): outer hairs form two irregular rows; inner-anterior row of recurved hairs absent; inneranterior row of stout setae represented by few (3–4) stout blunt setae in proximal part of tibia; inner field of stout pointed setae reduced: in middle 1/3 of tibia represented by irregularly situated short pointed bipectinate setae (2–3 in cross section), near apex of tibia represented by irregularly situated dense longer arches setae, on other parts of tibia represented by stout pointed setae as sparse and small as on tibiae of middle and hind legs.

Hind tibia ( Figs 601–602 ): each of three rows of stout setae—outer-anterior, outer-posterior and inner-anterior ones—consists of pointed stout setae; hairs located between outer-anterior and outer-posterior rows, numerous and form mostly one irregular row; hairs posteriad of outer-posterior row of stout setae located irregularly.

Claws with 5–6 denticles on rigid portion, with or without several minute denticles on articulatory portion.

Tergalii ( Figs 591 , 603, 608 ) moderately wide; on both lamellae main trachea without branches; dorsal lamella with costal margin most convex in proximal part and anal margin most convex in middle part, gradually narrowed toward apex, with short slender apical filament; ventral lamella widest near base, gradually narrowed toward apex, with short slender apical filament.

Male genitalia in last larval instar ( Figs 604–605 ): protogonostyli short and separated one from another by shallow emargination. Each protopenis lobe elongate-triangular, gradually stretched to gonopore-bearing process; gonopores opened caudally.

Subimago. CUTICULAR COLORATION. Cuticle mostly brown. Mesonotum dark brown with colorless achromozones and pair of stripes on posterior scutal protuberances; chromozones of medioscutum and submedioscutum equally colored by brown ( Fig. 609 ). Wings dark brown due to dark brown ring at base of each microtrichion; microtrichia blackish-brown (as in Fig. 438 ). Abdominal terga and sterna mostly brown with small colorless sigilla ( Figs 611–612 ).

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 (as in Fig. 473 ).

Imago. Described by Eaton (1884, 1892), Kimmins (1934), Ulmer (1943), Traver & Edmunds (1969). Leg coloration as in Figs 597–598 . Abdominal terga I and VII–IX dark brown, terga II-VI light with lateral triangular dark brown markings as in Fig. 611 .

Eggs. Unknown.

Dimension. Fore wing length (and approximate body length) 8–9 mm.

Distribution. Panama ( Eaton 1884; this study); Costa Rica ( Ulmer 1943; Traver 1946 as Th. pedregoso ).

Stage association. Originally, Th. lepidus was described as male imago from Chiriqui province in Panama; till recently, its larva was unknown. The larval description given above, is nit based on a reared specimen, but on a male larva ready to molt to subimago, and a female last instar larva, collected close to the type locality. The male subimago, extracted from the larval exuviae, is attributed to Th. lepidus based on its coloration of abdomen and legs. Protoptera of female larva demonstrate hypodermal coloration of costal and subcostal fields ( Fig. 591 ) and presence of well developed costal cross veins proximad of bulla, that agrees with description of imago of Th. lepidus .

Abdominal coloration of male imago was described as following: «Abdominal segments 2–6 transparent whitish, each with the tip and an oblique stripe on each side recurrent therefrom, fuscescent; segments 7–10 rich brown-ochre, lighter or pale yellowish ochreous towards the sides and beneath, and narrowly edged with black at their distal dorsal border» ( Eaton 1884). Fuscescent, brown and black markings reported in this description, represent hypodermal pigmentation. The examined specimen, besides this hypodermal pigments, bears subimaginal cuticle, which has brown color (except small paired sigilla) and is covered with dark brown microtrichiae ( Fig. 612 ), that makes the whole abdomen brown.Position of darker brown hypodermal markings agrees with the description of imaginal abdomen( Fig.611 ).

Leg coloration of the male imago was described as follows: «Fore leg in opaque view, with the femur, tibia, and joints 3 and 4 of the tarsus pitch-brown, the remainder of the tarsus dull light yellowish ochreous, the tip of the tibia slightly tinged with pitch-black. Hinder legs in opaque view, with the femur light reddish brown or rufo-piceous, the tibia and tarsus opaque amber-yellowish» ( Eaton 1884). In contrast to many other species, all femora are entirely brown, fore tibiae have the same color, while middle and hind tibiae are much lighter. This hypodermal coloration is clearly visible through larval and subimaginal cuticles ( Figs 597–598 ). This specimen differs from the Eaton’s description only by coloration of fore tarsus, which has all joints equally dark.

Relationship. Besides Th. lepidus, Eaton described from the same place (province of Chiriqui in Panama) male and female imagines of another species, Thraulodes valens ( Eaton 1892) . Kimmins (1934) described and figured genitalia of both these species. He characterized the penis of Th. lepidus as following: «Lobes of the penis divergent, their apices rounded and turned more strongly outwards, and each bearing two spines. One, directed inwards and arising from the upper surface, is long and slender, and the other, on the outer lateral margin, is very small and directed basally» ( Kimmins 1934: 343-344, fig. 7), and penis of the lectotype of Th. valens as following: «Lobes of the penis divergent, apices rounded and furnished each with two spines; one, the longer, directed inwards, and the other basally» ( Kimmins 1934: 345, fig. 8). Thus, both species have a pair spines located on lateral projections of penis and directed basally. By this feature these two species differ from all other Thraulodes , whose lateral projections of penis are smooth and have no points. Traver and Edmunds (1967) gave figures of genitalia of Th. lepidus and Th. valens redrawn from the Kimmins’s paper ( Traver & Edmunds 1967: figs 27, 64), but ignored this feature and proposed synonymy between Th. lepidus and Th. pedregoso Traver 1946 , whose penis does not have these points ( Traver 1946: fig. 19; Traver & Edmunds 1967: fig. 58). Probably, Th. lepidus and Th. valens are closely related. According to the original descriptions, they have similar leg coloration (all femora mostly brown, fore tibia brown, middle and hind tibia yellowish), but differ in coloration of abdomen: in contrast to Th. lepidus , in Th. valens «dorsum of abdomen light raw umber-brown» ( Eaton 1892: 9).

Former synonymy. Mariano, Flowers and Froehlich (2011) proposed synonymy of Th. cryptodrylus and Th. lepidus and argued this in a single sentence: «After analyzing the holotype and paratypes of T. lepidus and T. cryptodrilus , we conclude that the species described by Nieto and Domínguez (2001) based on material from Mexico collected in 1981 is the same as T. lepidus , and is proposed here as a synonym». They did not specify, holotype and paratypes of which species did they examined and did not give original figures of these type specimens. According to the published figures and descriptions, these two species well differ one from another by genital structure and by coloration of legs and abdomen. The species name Th. cryptodrylus Nieto & Dominguez 2001 should be regarded as valid.

Crumpled subimaginal genitalia, extracted from larva ( Figs 606–607 ) do not allow to reveal all features of the imaginal genital structure; however, they allow to assume correspondence with the genitalia described for Th. lepidus ( Kimmins 1934: fig. 7), but do not allow to assume correspondence with the genital of Th. cryptodrylus , whose spears are much shorter and dorsal projection of styliger much wider apically ( Nieto & Dominguez 2001: figs 6–8). In Th. cryptodrylus definitive penis is as short as the dorsal extension of styliger; in my specimen it has similar length in pressed and crumpled condition, so in definitive condition it must be as long as described for Th. lepidus . Telopenes of the subimaginal penis have definitive length; they are as long as in imago if Th. lepidus , that is much longer than in imago of Th. cryptodrylus .

Figures

FIGURES 591–602. Thraulodes lepidus. 591, larva in dorso-lateral view with brown cuticular markings and blackish hypodermal markings on head, thorax, protoptera, legs and abdomen; 592–598, larval exuviae at the same magnification; 597–598, fore and hind larval legs with subimaginal legs inside; 599, larval fore tibia; 600, anterior side of hind femur; 601, hind tibia with focus on outer-posterior row of stout setae; 602, the same with focus on outer-anterior and inner-anterior rows of stout setae.

FIGURES 603–612. Thraulodes lepidus. 603, larva with brown cuticular markings and blackish hypodermal markings; 604– 605, cuticle of larval protogonostyli and protopenis; 606–607, subimaginal styliger with gonostyli and penis extracted from larva; 608, tergalius III; 609–610, subimaginal thorax extracted from larva; 611, abdom of male subimago extracted from larva; 612, its enlarged fragment. Abbreviations: cut.subim, brown subimaginal cuticle with small paired blanks; hyp.w, non-pigmented area of hypoderm visible through blanks of cuticle; hyp.b, dark brown hypodermal coloration.

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 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.