Electrogena brulini Wagner & Vuataz & Sartori 2017, sp. nov.

Electrogena brulini Wagner, sp. nov.

Electrogena gridellii sensu Belfiore (1996) pro parte, nec Belfiore (1982)

Nymph description: Length: Male: body 7–10 mm, cerci 8–12 mm. Female: body 8–11 mm, cerci 10–15 mm. Colouration of cuticle generally greyish, epidermal pigmentation reddish, well contrasted.

Head: surface with distinctive light and dark markings (Figs 6, 8, 10, 12), specific to this species; noteworthy the presence of spots (b), between (a) and (c) (Fig. 6); a pattern formed by a triangle (f) and a line (d) delimiting a white marking (e) (Fig. 10) disappearing almost entirely in last instar; a light line along the inner margin of compound eyes, a dark colouration behind the ocelli (Figs 8, 12). Labrum, rather slender, R_LBR = 4.3–5.4; anterior margin with one row of bristles, stout and short in the middle and elongated outwardly (Figs 40, 44). Mandible with a prostheca bearing 5–8 bristles (N_PRO), all bristles evenly thick, at the most the basal one a little thinner (Fig. 42). Addition of right and left N_PRO: 10–15 bristles. Maxillae with a row of 16–23 comb-shaped setae on anterior margin (N_ CBS), the 5th (starting from inner side) bearing 8–13 teeth (N_ TCB), outer margin of galea-lacinia with 4–20 setae (N_ OUT), inner margin and ventral face of the first segment of palpus bearing 5–29 thin setae (N_ PLP). Hypopharynx with laterally expanded superlinguae, densely covered with long thin setae, apex of lobes with long setae (as E. gridellii in Fig. 49), sometimes missing when worn or very difficult to see because obscured by dirt as in Fig. 48. Labium, ventral face, only inner third of the paraglossae with bristles (rarely reaching half of the width) (Fig. 46), R_ GLA = 2.8–3.7, R_GLB = 2.7–3.2.

Thorax: Pronotum with a well contrasted pattern but no reddish-brown spot (h), the lateral margins regularly rounded with a dark line (g) (Fig. 16). Mesonotum with several light brown markings, and a brown semilunar vertical one (arrow in Figs 18, 20). Coxa bicoloured: proximal half white, distal half dark grey (Figs 28, 30). Thoracic sterna: sclerites light, imaginal colouration becoming brown during nymph development. Legs: well contrasted pattern rather similar between fore-, mid and hind legs (Figs 28, 33). Femora dorsal face with four markings (distal ones can be joined) forming a white cross always reaching the anterior and the posterior margins, strong contrast visible at all instars (Figs 4, 32, 33); ventral face of femora with a large spot, generally double, a dark cuticular spot (Fig. 27, k) covering a reddish epidermal one (Fig. 27, j) already visible in young nymphs (Fig. 32); medium sized blunt pointed bristles on the dorsal face of forefemora (Fig. 36), more peaked in mid and hind femora (Fig. 37); only one (sometimes none) strong spine in the middle of the ventral face of all femora, near the outer margin (N_BVF). Tibia contrasted, distal quarter and proximal third light, middle darker (Figs 28, 33); pectinate setae scarce on foretibia, numerous on mid and hind tibia (Fig. 35, inset). Tarsi with proximal and distal part darkened (mainly on dorsal face), exceptionally forming a distinct ring on distal part; claws with 2 teeth, rarely 3 (N_CLW).

Abdomen: Terga with contrasted markings: terga IV–V (sometimes also VI) generally with a large dark triangle on the anterior margin (Fig. 2), in dark nymphs, only light spots subsisting; terga posterior margin light, rarely with grey line on terga I–VIII, absent on tergum IX; terga II–VII with anterolaterally a very tiny, light, reddish-brown spot, generally covered by the previous tergum, smaller than the posterolateral one (Fig. 22); terga II–IX posterolaterally with a reddish-brown spot, faint in terga VIII-IX (Fig. 22); no contrast between terga VII and VIII–X (Fig. 2); tergum X dark with a light marking on each side (Fig. 14); posterior margin of each tergum with thin and elongated spines with microdenticulations at their bases. Sterna II–VIII with a dark, arch-shaped cuticular pattern, epidermis always entirely light (Fig. 24), except some nymphs with only a very faint pattern becoming brown as E. gridellii in Fig. 25; ganglionic chain brownish, only last ganglion and the thoracic ones larger and darker violet (Fig. 24). In the male last instar nymphs, styliger processes and titillator visible through sternum IX, but titillators too poorly formed to be diagnostic. Gill I tongue-shaped, gills II–VI broad and asymmetrical, gill VII elongated, narrow at apex and slightly pointed (Fig. 50). Paracercus and cerci light, becoming darker only in the last instars, colouration fading apically.

Male imago: Length: body 7.5–9 mm, forewing 8.5–10 mm, cerci 20–25 mm.

Head: Eyes clearly separated, sclerite joining the compound eyes weakly rounded forming a wide V (Fig. 84).

Thorax: dark brown (Figs 52, 54). Wings veins yellowish-brown; costa, subcosta and radius anterior brighter yellow; distal half of costal and subcostal fields sometimes milky (Fig. 64). Distal part or entire forefemora darkened (Figs 60–61); mid and hind femora dorsally with a brown spot at the distal third and a second spot, variably visible at the proximal third (Fig. 60); ventral face of mid and hind femora with a brown spot at the distal third (Fig. 61).

Abdomen: Terga dorsally all uniform medium brown with a pair of lighter comma-shaped markings (Fig. 56); posterolaterally a darker marking and laterally a light area (Fig. 54), anterolaterally sometimes very slightly brownish (Fig. 54). Sterna pale with a large subtriangular light orange-brown marking covering more or less the entire face, ganglia violet (Fig. 58). Cerci brown, colouration fading to the apex. Penis lobes regularly rounded, can be slightly bent outwards, distance between lobes ranging from zero up to a ninth of a penis lobe width (Fig. 68), numerous small dorsal spines basolaterally on penis lobes (Fig. 72). Titillator massive, with generally two teeth, shape variable (Figs 75–78). Styliger almost straight with lateral humps (Fig. 66).

Female imago: Length: body 7.5–10 mm, forewing 10–12 mm, cerci 16–20 mm. Same general colouration as in male, but lighter; no colour difference between abdomen and thorax (Figs 86, 88). Wings with same colouration as in male (Fig. 90). Rusty colouration behind ocelli (n), area between the pair of ocelli and the compound eyes not darkened (l), sclerite joining the compound eyes with only laterally a distinct thin brown line on the margin (Fig. 98, m). Subgenital plate covering about half of sternum VIII surface, subanal plate tapering to apex, in apical view narrow and lateral margins rolled up towards the inside (Figs 94, 95).

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

Egg: Dimensions: 150/110µm; micropyle: 10/6.5µm. Chorion entirely and regularly covered with relatively dense microgranules, KCT’s evenly distributed over the surface, but more concentrated and somewhat larger on one pole (about the third of the egg) (Fig. 100). Micropyle bordered with the same microgranules as surface (Fig. 101).

Etymology. From Michel Brulin (France), the initiator and driving force of the inventory of mayflies in France. A man who, despite his vast knowledge, remains humble and amazed by the life of these insects.

Diagnosis. Nymph: general colouration contrasted, all femora with a large spot on the ventral face; two teeth on claws; 1 bristle (can miss) on ventral face of femora, near the outer margin; bristles of femora bluntly pointed; prostheca consisting in 5–7 bristles (Fig. 42).

The nymph of Electrogena ozrensis (Tanasijevic, 1975) has not yet been described. Nevertheless, samples and rearing were performed in April 2017 close to the type-locality in Tuzla (Bosnia). On the basis of the original description, it was possible to link the reared imagines with E. ozrensis, and then with the nymphs. This work being not a revision of the genus Electrogena, we add only some elements allowing to separate Electrogena brulini sp. nov. from the other cited species; essentially based on the present work and on the complete work of Belfiore (1997):

- the double large reddish and grey spot on the ventral face of femora has never been mentioned in European Electrogena species. Nevertheless, this character should not be confused with other colourations that are common: E. affinis usually with a single well- marked spot; E. lateralis sometimes with a faint spot; E. quadrilineata and E. ozrensis with a similar double coloured spot, but the cuticular one more extended, reaching nearly the inner and the outer margins; E. ujhelyii only with a variable cuticular colouration, a transverse distal band (can reach the apex), a longitudinal band on the inner margin, up to almost the whole face grey in dark populations.

- the absence of thin setae along the anterior margin of femora discriminates E. brulini from E. affinis.

- the presence of two teeth on the claws discriminates E. brulini from E. lateralis and E. lunaris (one tooth) and generally from E. affinis (usually three teeth).

- the absence of several spines on the ventral face of all femora discriminates E. brulini from E. fallax, E. ozrensis, E. quadrilineata, E. ujhelyii and Anapos zebratus.

- the middle sized blunted bristles on the dorsal face of femora discriminates E. brulini from the long, narrow and pointed bristles as in E. gridellii, from the rounded distal bristles as in E. grandiae and E. hyblaea, from the truncate parallel bristles as in E. ozrensis and E. quadrilineata.

- the few bristles forming the prostheca discriminates E. brulini from E. gridellii.

- the sterna colouration in E. brulini (Fig. 24) is less extensive, lateral spots not reaching the posterior margin as in E. ujhelyii (Fig. 26). This precision may be important, since both species are sympatric in Friuli-Venetia.

- the regular and more or less symmetrical form of the expansions of the pronotum discriminates it from Electrogena braaschi (Sowa, 1984) which has a unique form of expansions, extending forwards.

Imago: dorsal face of mid and hind femora with a distinct and an indistinct dark band (Fig. 60); ventral face of mid and hind femora with a distinct dark spot (Fig. 61); venation of wings pale brownish; terga pale reddish-brown, posterolaterally a brown spot and anterolaterally a very slightly brownish little marking (Figs 54, 56, 88); titillators with 2 apico-lateral teeth (Figs 75–78).

In nymph stage, E. brulini can currently be discriminated from all other species except E. calabra. As we had no fresh specimens and as the meristic and ratio characters are of no help to discriminate E. brulini from E. calabra in the nymph stage, the adults have to be compared to exclude a possible synonymy. In imagines, the very inconspicuous spots of the terga discriminate E. brulini from E. calabra which has, according to Bauernfeind & Soldan (2012) “Basolaterally a rounded dark reddish spot near the anterior border and a smaller dot near the posterior border of segments II–VIII”. In E. brulini, the comparison of Figs 2 /52 and 3/53 shows that the cuticular colouration is little conservative, but the comparison of Figs 22 /54 and 23/55 shows that the epidermal lateral spots are more conservative. As we observed such characteristics in our rearing of different Electrogena species, we can assume that it is true in E. calabra too. In females, the comparison with the original description seems to indicate that the subgenital plate covers about ¾ of sternum VIII surface in E. calabra (only about the half in E. brulini) and that the subanal plate does not taper to the apex in E. calabra. This imaginal colouration, represented in Belfiore (1995) and the characteristics of the subgenital and subanal plates, exclude a synonymy. Nevertheless, a thorough study is needed to better separate the two species in both adult and nymph stages.

Material examined: HOLOTYPE: 1 male nymph (preserved in ethanol), CH / TI, Meride, Gaggiolo, 45.8973°N 8.9382°E 715 m, 3.V.2014, A. Wagner leg (GBIFCH00341000) [MZL]. PARATYPES: 16 males, 15 females, 36 nymphs, 4 male subimagines, 2 female subimagines: same sampling data as the holotype; 35 nymphs: same locality as holotype, 18.IV.2014; 1 nymph: CH / TI, Stabio, Gaggiolo, 45.8388°N 8.9129°E 379 m, 18.IV.2014; 1 nymph: CH / TI, Arzo, Gaggiolo, Arzo, 45.8753°N 8.9448°E 492 m, 18.IV.2014; 3 nymphs: CH / TI, Arzo, Gaggiolo, upstream of Arzo, 45.8787°N 8.9494°E 507 m, 18.IV.2014; 18 nymphs: IT / LO, Valle Santa Croce, Torrente Molgoretta, 45.7176°N 9.3448°E 304 m, 4.IV.2015; 1 nymph: IT / FV, Buja, Fiume Ledra, 46.2282°N 13.1086°E 175 m, 6.IV.2015; 11 nymphs: IT / FV, Povoletto, Via Reclusane, 46.2658°N 13.3126°E 158 m, 6.IV.2015; 7 nymphs: IT / FV, Savogna, Torrente Rieca, 46.1845°N 13.5821°E 541 m, 6.IV.2015; 24 nymphs: IT / FV, Stregna, Torrente Erbezzo, 46.1287°N 13.5699°E 232 m, 6.IV.2015; 16 nymphs: IT / FV, Prepotto, Fiume Judrio, 46.0826°N 13.5434°E 145 m, 6.IV.2015; 18 nymphs: SL / LC, Kocevje, Reka, 45.5695°N 14.8051°E 512 m, 8.IV.2015; 4 nymphs: SL / LC, Kocevje, Gornja Briga, 45.5327°N 14.7935°E 625 m, 8.IV.2015; 3 nymphs: SL / LC, Kostel, Kolpa tributary, 45.4646°N 14.8425°E 242 m, 8.IV.2015; 2 nymphs: SL / LC, Ribnica, Ribnica tributary, 45.7359°N 14.7103°E 488 m, 8.IV.2015; 6 nymphs: SL / LC, Sodrazica, Bistrica, Jelovec, 45.7691°N 14.6222°E 547 m, 8.IV.2015; 12 nymphs: SL / LC, Sodrazica, Bistrica, Zimarice, 45.7763°N 14.6111°E 552 m, 8.IV.2015; 4 nymphs: SL / LC, Sodrazica, Podklanec, 45.7655°N 14.5811°E 581 m, 8.IV.2015; 1 nymph: SL / IC, Bloke, Bloscica, 45.7879°N 14.4761°E 727 m, 8.IV.2015 [all MZL]; 3 male imagines, 3 female imagines, 3 nymphs: CH / TI, Meride, Gaggiolo, Spinorolo, 45.8973°N 8.9382°E 616 m, 3.V.2014 [NHMW]; 12 nymphs: IT / FV, Grimaco, Rio Godriana, 46.1574°N 13.5941°E 292 m, 6.IV.2015 [NHMW]; 12 nymphs: SL / LC, Kocevje, Kocevska Reka, 45.5695°N 14.8051°E 512 m, 8.IV.2015 [NHMW].

Other material examined: 1 nymph: CH / TI, Chiasso, Breggia, 45.8407°N 9.0218°E 230 m, 6.III.1948, J. Aubert leg; 1 nymph: CH / TI, Stabio, Laveggio, 45.8463°N 8.9399°E 340 m, 15.III.1990, B. Jann leg; 3 nymphs: CH / TI, Meride, Gaggiolo, Spinorolo, 45.8973°N 8.9382°E 616 m, 3.IV.2012, B. Jann leg; 1 nymph: IT / FV, Buja, Fiume Ledra, Andreuzza, 46.2068°N 13.0947°E 171 m, 6.IV.2015; 4 nymphs: IT / FV, Attimis, Torrente Racchiusano, 46.1733°N 13.3330°E 230 m, 6.IV.2015; 2 nymphs: IT / FV, Savogna, Torrente Rieca, 46.1845°N 13.5821°E 541 m, 6.IV.2015; 3 nymphs: IT / FV, Grimaco, Rio Godriana, 46.1574°N 13.5941°E 292 m, 6.IV.2015; 30 nymphs: IT / FV, San leonardo, Torrente Cosizza, 46.1492°N 13.5638°E 218 m, 6.IV.2015; 1 nymph: IT / FV, Prepotto, Fiume Judrio tributary, 46.0827°N 13.5427°E 147 m, 6.IV.2015; 1 nymph: SL / LC, Kostel, Kolpa tributary, 45.4646°N 14.8425°E 242 m, 8.IV.2015; 14 nymphs: SL / IC, Bloke, Bloscica, 45.7879°N 14.4761°E 727 m, 8.IV.2015, A. Wagner leg [MZL].