Electrogena gridellii ( Grandi, 1953 )

Wagner, Andre, Vuataz, Laurent & Sartori, Michel, 2017, Electrogena brulini sp. nov. and E. vipavensis Zurwerra & Tomka, 1986 syn. nov. revealed by integrative taxonomy of E. gridellii (Grandi, 1953) (Ephemeroptera: Heptageniidae), Zootaxa 4362 (3), pp. 359-384 : 375-379

Electrogena gridellii ( Grandi, 1953)

Heptagenia gridellii: Grandi 1953 male and female imagines Ecdyonurus gridellii: Belfiore 1981 lectotype designation Ecdyonurus gridellii: Belfiore 1982 nymph description

nec Ecdyonurus gridellii sensu Zurwerra & Tomka 1984

nec Ecdyonurus gridellii sensu Sartori & Dethier 1985

Electrogena gridellii: Zurwerra & Tomka 1985 new combination nec Electrogena gridellii sensu Sartori 1987

Electrogena gridellii: Gaino et al. 1987 egg description

Electrogena vipavensis: Zurwerra & Tomka 1986 female imago, male subimago, nymph exuvia, egg NEW SYNONYM

Nymph description. Length: Male: body 8.5– 12 mm, cerci: 11–16 mm. Female: body 12–14 mm, cerci: 13–17 mm. General colouration dull, little contrasted.

Head: surface little contrasted ( Figs 7, 9, 11, 13 ); noteworthy the presence of a double sagittal faint (sometimes lacking) triangular marking on the anterior margin of head (a) and a lateral light zone ahead the compound eyes (c) ( Fig. 7 ); no contrasted pattern on the posterior part ( Fig. 11 ), only a greyish band on the posterior margin; a dark marking touching the compound eyes, no colouration behind the ocelli ( Figs 9, 13 ). Labrum rather slender R_LBR = 4.2–4.6. Mandible with a prostheca bearing 9–20 bristles (N_PRO), the first bristles thick, then the size of them tapering, often ending with very tiny hairy bristles (not counted) ( Fig. 43 ). Addition of right and left N_PRO: 22–39 bristles. Maxillae with a row of 19–26 comb-shaped setae on anterior margin (N_CBS), the 5th (starting from inner side) with 10–15 teeth (N_TCB), outer margin of galea-lacinia bearing 11–43 setae (N_OUT), inner margin and ventral face of the first segment of palpus bearing 24–46 thin setae (N_PLP). Hypopharynx with laterally expanded superlinguae, densely covered with long thin setae, apex of lobes with long setae ( Fig. 49 ), sometimes missing when worn or very difficult to see because obscured by dirt as E. brulini in Fig. 48 . Labium, ventral face, bristles reaching about half of the width of the paraglossae ( Fig. 47 ), inner distal margin can be concave, R_GLA = 3.1–5.2, R_GLB = 2.5–3.0.

Thorax: Pronotum without a pattern, faint, but presence of a reddish-brown spot (h), usually hidden by the head, the lateral margins regularly rounded with a faint greyish line (g) ( Fig. 17 ). Mesonotum with several light brown markings and an oval-shaped spot in young instars (arrow in Fig. 19 ), becoming an oblique semilunar marking (arrow in Fig. 21 ). Coxa little contrasted: proximal half white, distal part greyish ( Fig. 31 ). Thoracic sterna: sclerites light, imaginal colouration becoming brown during nymph development. Legs: faint ornamentation rather similar between fore-, mid and hind legs ( Figs 29 , 34 ). Femora dorsal face with four (some can be joined) less contrasted brownish spots delimiting an often incomplete light cross, the weak contrast disappearing in the last instars ( Fig. 29 ); ventral face of femora very rarely with a greyish cuticular suffusion in last instars; all femora with long, narrow and pointed bristles on the dorsal face ( Figs 38, 39 ); only one (can miss) strong spine in the middle of the ventral face of all femora, near the outer margins (N_BVF). Tibia faint, when contrasted, only the apex lighter; pectinate setae scarce on foretibia, numerous on mid and hind tibia (as E. brulini Fig. 35 , inset). Tarsi distal quarter slightly darkened (mainly on dorsal face), exceptionally forming a less or more visible ring on distal part, colouration not strengthening toward the proximal part; claws with 2 teeth, rarely 1 or 3, exceptionally 0 or 4 (N_CLW).

Abdomen: Terga with little contrasted markings: terga (III) IV–VI (VII–VIII) anterior margin: grey slender triangle in the middle ( Fig. 3 ); terga (IV–VI and VIII–X) posterior margin: grey line, not visible when fused with entirely dark terga; terga II–VIII anterolateral epidermal brown spot larger than the posterolateral one ( Fig. 23 ), anterolateral spot hidden under the preceding terga in small nymphs, growing up to last instar ( Figs 23 ); terga II– VII posterolaterally with a reddish-brown spot ( Fig. 23 ); in the last instars, tergum VII (darker) contrasting with terga VIII–X ( Fig. 3 ), tergum X anterior half brownish with a light area in the middle, posterior half white with only a slight line on the posterior margin ( Fig. 15 ); posterior margin of each tergum with thin and elongated spines with microdenticulations at their bases. Sterna: no cuticular colouration except a light greyish stain, epidermis light in young nymphs, becoming brown in last instars ( Fig. 25 ); ganglionic chain brownish pigmented, thoracic ganglia a bit darker, in last instars, ganglia hardly visible due to the dark epidermal colouration ( Fig. 25 ). In the male last instar nymphs, styliger processes and titillator already visible through sternum 9, but titillators not enough formed to be diagnostic. Gill I tongue-shaped, gills II–VI broad and asymmetrical, gill VII elongated, narrow at apex and slightly pointed ( Fig. 51 ). Paracercus and cerci light, becoming darker only in the last instars, colouration fading apically.

Male imago: Length: body 11–13 mm, forewing 12–14 mm, cerci 31–36 mm.

Head: Eyes clearly separated, sclerite joining the compound eyes W-shaped, generally well-marked ( Fig. 85 ).

Thorax: dark brown ( Figs 53, 55 ). Wings veins all dark brown ( Fig. 65 ). Central part or entire forefemora darkened ( Figs 62–63 ); mid and hind femora dorsally with a very light transversal brown band ( Fig. 62 ); ventral face at most with a barely visible band ( Fig. 63 ). Abdomen: Terga II–VII (VIII) anterior margin brown with a pair of large subtriangular markings pointed backwards reaching or not the posterior margin and a dark marking between them, posterior margin darkened (as female in Fig. 87 ), these markings can be fused, covering the dorsal surface ( Fig. 53 ); in lateral view, the subtriangular markings are fused with the anterolateral and the posterolateral markings of the preceding tergum building a large oblique band ( Fig. 55 ). Sterna pale with a large subtriangular light orange-brown marking covering more or less the entire face, ganglia violet ( Fig. 59 ). Cerci brown, colouration fading to the apex. Penis lobes subrhomboidal, narrowed towards the apex, slightly bent inwards ( Fig. 69 ), only a few small dorsal spines basolaterally on penis lobes ( Fig. 73 ). Titillator convex before the unique tooth, than concave until a more or less visible basal tip ( Figs 79–81 ). Styliger almost straight with lateral humps (as E. brulini on Fig. 66 ), but humps can be very inconspicuous as in Fig. 67 .

Female imago: Length: body: 11–14 mm, forewing: 14–17 mm, cerci: 25–32 mm.

Same general colouration as in male; only thorax somewhat lighter ( Figs 87, 89 ). Wings veins all medium brown ( Fig. 91 ). Light area behind the pair of ocelli (n), area between the pair of ocelli and the compound eyes dark (l), sclerite joining the compound eyes with an extended dark brown area ( Fig. 99 , m). Subgenital plate covering ¾ of the sternum VIII surface, subanal plate in ventral and apical view rounded ( Figs 96, 97 ).

Male and female subimago: Same colouration as imago, but paler. Wings without pattern, entirely grey.

Egg: Dimensions: 155/120 µm; micropyle: 11/6.5 µm.

Chorion entirely and regularly covered with relatively dense microgranules, KCT’s evenly distributed over the surface, more concentrated only on a very restricted area of one pole ( Fig. 102 ). Micropyle bordered with the same microgranules as surface ( Fig. 103 ).

Diagnosis. Nymph: general colouration faded, femora without spot on the ventral face, two teeth on tarsal claws; (0) 1 bristle on ventral face of femora, near the outer margin; bristles of femora long, thin and pointed; prostheca consisting in 9–20 bristles ( Fig. 43 ), terga anterolateral spot smaller than the posterolateral one ( Fig. 23 ).

Imago: dorsal face of mid and hind femora with an inconspicuous band ( Fig. 62 ); ventral face of mid and hind femora without colouration ( Fig. 63 ); wings veins dark brown in male ( Fig. 65 ), medium brown in female ( Fig. 91 ); terga well contrasted, white and dark brown, posterolateral and anterolateral spots well visible forming an oblique streak ( Figs 55 , 57 , 89 ); titillators with 1 apico-lateral tooth ( Figs 79–81 ).

Although many differences in colorations make it possible to easily separate E. brulini from E. gridellii , the two species have always been confused because the value of colouration characters is underrated (or because of the use of old faded specimens); therefore those characters are generally omitted. Among colouration characters are true patterns, but also simple colourations which seem to have even less taxonomic importance. However, some of these are conservative characters, visible both in nymphs and adults, and have been positively tested as to their discriminating value to separate E. brulini from E. gridellii .

Only the discriminating characters between E. gridellii and E. brulini tested and easily usable in the vast majority of cases are presented here.

At the nymphal stage:

- all colourations of E. brulini contrasted, those of E. gridellii very dull.

- pattern and different markings contrasted on the head in E. brulini ( Figs 6,8,10 , a–f), no pattern and only some pale markings (notice the absence of spot (b) ) in E. gridellii ( Figs 7, 9, 11 ).

- each prostheca consisting in 5-8 bristles (all bristles evenly thick, at the most the basal one a little thinner) in E. brulini ( Fig. 42 ), 9–20 bristles (the first bristles thick, then the size of them tapering, often ending with very tiny hairy bristles) in E. gridellii ( Fig. 43 ).

- pronotum with a contrasted pattern but no reddish-brown spot (h), the lateral margins with a dark line (g) in E. brulini ( Fig. 16 ), faint, but presence of a reddish-brown spot (h), usually hidden by the head, the lateral margin with a faint greyish line (g) in E. gridellii ( Fig. 17 ).

- mesonotum with brown semilunar vertical markings in all instars in E. brulini (arrow in Figs 18, 20 ), ovalshaped spot becoming an oblique semilunar marking in E. gridellii ( Figs 19, 21 ).

- femora ventral face always with a visible dark (generally double) spot in E. brulini ( Fig. 27 ), at most with a greyish cuticular suffusion in the last instars in E. gridellii .

- bristles of dorsal face medium sized blunt pointed on forefemora, more peaked in mid and hind femora in E. brulini ( Figs 36, 37 ), thin, long and pointed on all femora long in E. gridellii ( Figs. 38, 39 ).

- coxa bicoloured, proximal half white, distal half dark grey in E. brulini ( Figs 28, 30 , 32 ), little contrasted in E. gridellii ( Fig. 31 ).

- tibia contrasted, distal quarter and proximal third light, middle darker in E. brulini ( Fig. 28 , 32, 33 ), entirely faint, when contrasted, only the apex lighter in E. gridellii .

- tergum X dark with a light marking on each side in E. brulini ( Fig. 14 ), anterior half brownish with a light area in the middle, posterior half white with only a slight line on the posterior margin in E. gridellii ( Fig. 15 ).

- sterna with an arch-shaped cuticular pattern, epidermis always entirely light in E. brulini ( Fig. 24 ), without cuticular pattern, epidermis light in young nymphs, becoming brown in last instars in E. gridellii ( Fig. 25 ).

At imaginal stages:

- general colouration of abdomen uniform in E. brulini ( Figs 56 , 86 ), contrasted in E. gridellii ( Figs 57 , 87 ).

- wings veins yellowish-brown; costa, subcosta and radius anterior brighter yellow in E. brulini ( Figs. 64 , 90 ), regularly dark brown in male, medium brown in female in E. gridellii ( Figs 65 , 91 ).

- mid and hind femora dorsally with a brown spot at the distal third and a second spot, variably visible, in the proximal third in E. brulini ( Fig. 60 ), with a very light transversal brown band in E. gridellii ( Fig. 62 ).

- mid and hind femora ventrally with a brown spot at the distal third in E. brulini ( Fig. 61 ), at most with a barely visible band in E. gridellii ( Fig. 63 ).

- male: sclerite joining the compound eyes weakly rounded forming a wide V in E. brulini ( Fig. 84 ), W-shaped in E. gridellii ( Fig. 85 ).

- male: titillator massive, straight or concave before the two teeth (rarely one or three), but no basal tip in E. brulini ( Figs 75–78 ), convex before the unique tooth, than concave until a more or less visible basal tip ( Figs 79–81 ).

- female: subgenital plate covering about half of sternum VIII surface in E. brulini ( Fig. 95 ), covering ¾ of the sternum in E. gridellii ( Fig. 97 ).

- female: subanal plate tapering to apex, in apical view narrow and lateral margins rolled up towards the inside in E. brulini ( Figs 94, 95 ), subanal plate in ventral and apical view rounded in E. gridellii ( Figs 96, 97 ).

At both stages:

- nymph pattern ( Fig. 10 , d - f) disappearing, only narrow coloured lines remaining laterally on posterior margin in female imagines in E. brulini ( Fig. 98 , m), nymph posterior part of the head with only a greyish band (so faint that it is not visible on photos) on the posterior margin, becoming a large centered brown band in female imagines in E. gridellii ( Fig. 99 , m).

- a light line along the inner margins of compound eyes, a dark colouration behind the ocelli ( Figs 8, 12 ); characters still present in female imagines in E. brulini ( Fig. 98 , 1 , n), a dark marking touching the compound eyes, no colouration behind the ocelli ( Figs 9, 13 ); characters still present in female imagines in E. gridellii ( Fig. 99 , 1 , n).

- terga anterolateral spot small and hidden, posterolateral bigger in E. brulini ( Figs 22 , 54 , 88, 92 ), anterolateral spot large, posterolateral spot little developed in nymphs, grows and merges with dorsal coloration in E. gridellii imagines ( Figs 23 , 55 , 89, 93 ).

Rationales for the proposed synonymy. The type material of E. vipavensis currently housed in MZL is composed of the following items:

- the holotype, a male subimago (N° 4155) with corresponding exuvia on slide (N° 4155_D_a_male). Subimago: sclerite joining the compound eyes W-shaped, styliger straight with lateral humps, all the colouration faded, but the drawings in the original description fits with our contrasted E. gridellii subimagines: anterior margin of terga III–V with a pair of subtriangular markings pointed backwards and a spot between them, posterior margin darkened, posterolateral part of terga III–V with a dark marking near the border fused with the anterior margin marking of next tergum, an oval white area oblique from the anterolateral corner. Exuvia: all femora with long, narrow and pointed bristles on the dorsal face, N_BVF: 0, N_CLW: 2, N_PRO: 11 / 11. According to all observed characters we found no difference between the holotype and E. gridellii .

- paratype female abdominal segments VII–X (N° 4175) with corresponding exuvia on slide (N° 4175_a_fem) (assumed to be the paratype drawn in the original description because of the precision « fem » on the exuvia slide) and the forewings on slide (N° 4175_b). According to the original drawing, the pattern of the terga III–V in lateral view is composed by the following elements: a large oval white area oblique from anterolateral corner, an anterolateral spot, posterolateral spots, a lateral dark streak at base of terga, central part of the subanal plate tapering towards apex. Exuvia: all femora with long, narrow parallel and truncate bristles on the dorsal face, N_BVF: numerous, N_CLW: 2, N_PRO: 9 / 9. According to all observed characters we found no difference between this paratype and E. ujhelyii except that the 2–3 posterolateral spots of the original drawing are usually fused in E. ujhelyii .

- paratype female abdominal segments VII–X (N°4291) with corresponding exuvia on slide (slide 4291_a). Exuvia: all femora with long, narrow and pointed bristles on the dorsal face, N_BVF: 0, N_CLW:2, N_PRO: 9. New identification: E.gridellii .

- paratype female abdominal segments VII–X (N° 4223). Central part of the subanal plate tapering towards apex, but not sufficient for a secure identification: E. cf ujhelyii .

- paratype female abdominal segments VII–X (N° 4198) plus a second sample with 5 legs and 1 forewing (same number N° 4198). Not sufficient for identification: Electrogena sp.

Together with the type material and from the same sampling data: one exuvia named E. ozrensis on slide (N° 4167_a). All femora with long, narrow and pointed bristles on the dorsal face, N_BVF: 0, N_CLW:2, N_PRO: 14. New identification: E. gridellii .

Our examination of the type material of E. vipavensis indicates that the holotype, male subimago (N° 4155) and its exuvia on slide (N° 4155_D_a_male) and the female paratype exuvia on slide (N° 4291_a) are conspecific with E. gridellii . Therefore, we propose that Electrogena vipavensis Zurwerra & Tomka, 1986 should be considered as a subjective junior synonym of Electrogena gridellii ( Grandi, 1953) syn. nov.

After comparison of the original drawing with our material and re-investigation of the female paratype exuvia slide (N° 4175_a_fem), we consider that this specimen is conspecific with E. ujhelyii .

Material examined: 97 male imagines, 45 female imagines, 8 nymphs, 140 nymph exuviae, 31 male subimagines, 39 female subimagines: IT / FV, San Dorligo della Valle, Rosandra , Bagnoli Superiore , 45.6195°N 13.8654°E 91 m, 9.IV.2015 (emerged 9.IV–23.V.2015); 75 nymphs: same locality, 7.IV.2015; 11 nymphs: IT / FV, Povoletto , Via Reclusane , 46.2658°N 13.3126°E 158 m, 6.IV.2015; 1 nymph: IT / FV, Attimis , Rio Valle tributary, 46.1748°N 13.3211°E 177 m, 6.IV.2015; 6 nymphs: IT / FV, Attimis , Torrente Racchiusano , 46.1733°N 13.3330°E 230 m, 6.IV.2015; 1 nymph: IT / FV, Stregna , Torrente Erbezzo , 46.1287°N 13.5699°E 232 m, 6.IV.2015; 1 nymph: IT / FV, Prepotto , Fiume Judrio , 46.0826°N 13.5434°E 145 m, 6.IV.2015; 15 nymphs: IT / FV, Prepotto , Fiume Judrio tributary, 46.0827°N 13.5427°E 147 m, 6.IV.2015; 1 nymph: SL / IS, Koper, Rizana , 45.5328°N 13.8729°E 66 m, 7.IV.2015, A. Wagner leg. [ MZL]; 1 nymph: IT / FV, Manzano, Fiume Natisone basin, Oleis, 46.02°N 13.38°E 75 m, F. Desio leg, E . Bauernfeind det. [NHMW]

E. vipavensis : one male subimago holotype (N° 4155 with exuvia on slide), 4 female paratypes, SL / GO, Ajdovscina, Stream Vipava, 16.IV.1983, Hefti, Tomka & Zurwerra leg. [ MZL]

Figures

FIGURE 1. Bayesian majority-rule consensus tree of Electrogena reconstructed from the CO1 data set, and designed in iTOL v. 3.5.3 (Letunic & Bork 2016). Electrogena brulini is highlighted in green. Circles on branches indicate Bayesian posterior probabilities> 0.9.

FIGURES 2–21. General overview of the nymphs with emphasis on different markings and colourations of Electrogena brulini(Figs 2,4, 6,8, 10, 12, 14, 16, 18,20)and Electrogena gridellii(Figs 3, 5, 7,9,11, 13,15, 17, 19, 21).Figs 2–3:habitus, dorsal view; Figs 4–5: habitus, ventral view; Figs 6–7:head infrontal view; Figs 8–9: head in dorsal view; Figs 10–11: head in postero-dorsal view; Figs 12–13: ocelli; Figs 14–15: tergites IX–X; Figs 16–17: pronotum; Figs 18–21: mesonotum. Arrows: specific colouration details.

FIGURES40–51.Mouth parts and gills of Electrogena brulini (Figs 40, 42, 44, 46, 48, 50) and Electrogena gridellii (Figs 41, 43, 47, 49, 51). Figs 40–41: dorsal face of labrum; Figs 42–43: mandible with prostheca; Figs 44–45: anterior margin of dorsal face of labrum, central part; Figs 46–47 ventral face of glossae; Figs 48–49: hypopharynx in dorsal view; Figs 50–51: gills I– VII, without the bunch of filaments.

FIGURES 22–31. Nymph details of Electrogena brulini (Figs 22, 24, 27, 28, 30), Electrogena gridellii (Figs 23, 25, 29, 31) and Electrogena ujhelyii (Fig. 26). Figs 22–23: abdominal segments VII–X in lateral view; Figs 24–26: abdomen in ventral view; Fig. 27: hind femora in postero-ventral view; Fig. 28: latero-ventral general overview; Fig. 29: dorsal face of femora; Figs 30–31:thorax in lateral view, emphasis on coxa. Arrows:specific colouration details.

FIGURES 32–39. Nymph of Electrogena brulini (Fig. 32); legs and parts of legs of Electrogena brulini (Figs 33, 35–37) and Electrogenagridellii (Figs 34, 38,39).Fig.32:habitus of ayoung nymph in latero-dorsal view; Figs33–34:dorsal face of fore-, mid and hind legs; Fig 35: ventral face of fore-, mid and hind legs, emphasis on a pectinate setae; Figs 36, 38: dorsal face of forefemora, emphasis on bristles; Figs 37, 39: dorsal face of hind femora, emphasis on bristles. Arrows in Fig. 32: example of different markings already visible in young nymphs.

FIGURES68–85.Electrogena brulini (Figs 68, 72, 75–78, 84), Electrogena gridellii (Figs 69, 73, 79–81, 85)and Electrogena grandiae(Figs 70,71, 74, 82, 83). Figs68–74:penis inventral view;Figs 75–83:titillators;Figs 84–85:head withemphasis on the posterior sclerit between the eyes.

FIGURES52–55.Male imagines' habitus of Electrogena brulini (Figs 52, 54)and Electrogena gridellii(Figs 53, 55).Figs 52– 53:dorsal view; Figs 54–55: lateral view. Arrows: markings on the tergite VI.

FIGURES 56–67. Details of male imagines of Electrogena brulini (Figs 56, 58, 60, 61, 64, 66) and Electrogena gridellii (Figs 57, 59, 62, 63, 65, 67).Figs 56–57: terga; Figs 58–59:terga; Figs 60, 62:dorsal face of fore- mid and hind femora; Figs 61, 63: ventral face of fore- mid and hind femora; Figs64–65:forewing; Figs 66–67: sterna VIII–IXwith styliger.

FIGURES 86–99. Details of female imagines of Electrogenabrulini (Figs 86, 88, 90, 92, 94, 95, 98) and Electrogena gridellii (Figs 87, 89, 91, 93, 96, 97, 99). Figs 86–87: terga; Figs 88–89: habitus, lateral view; Figs 88–89: forewing; Figs 92–93: subanal and subgenital plate in lateral view; Figs 94, 96: subanal plate in apical view; Figs95, 97:subanal andsubgenital plate; Figs 98–99:head and pronotum.Arrows: specific colouration details.

FIGURES 100–103. Eggs of Electrogena brulini (Fig. 100–101) and Electrogena gridellii (Figs 102–103). Figs 100, 102: general view; Figs 101, 103: emphasis on the micropyle.