Zwicknia, Muranyi, 2014

Reding, Jean-Paul G., 2018, Stoneflies of the genus Zwicknia Murányi, 2014 (Plecoptera: Capniidae) from western Switzerland, Zootaxa 4382 (2), pp. 201-241 : 215-216

Key to larvae of Zwicknia and Capnia from western Switzerland

Since the larvae of the genus Zwicknia are not easily separable from those of other Capniidae , a preliminary generic key, which, however, only takes into account specimens of C. vidua vidua and C. nigra from alpine and prealpine regions, is proposed. As we did not have the opportunity to counter-check our topotypical larval material of C. nigra from the Arve River of the Greater Geneva Region ( Pictet 1833) upon which the present illustrations are based with larvae of C. nigra from the Eastern Palearctic ecozone ( Vinçon & Sivec 2011; Chen & Du 2017b), the application range of the proposed larval key must be restricted in the same way. A similar, but reversed, caveat must be made about the larvae of C. vidua vidua : since we did not have topotypical material for this species at our disposal and since published descriptions of the larva of this species are contradictory (e. g. Lillehammer 1988: 135, Figs. 242 and 243 vs Raušer 1980: 121, Figs. 34 /10 and 34/11) or perhaps targeting different species, the validity of the proposed key could not be tested for material outside western Switzerland. Note also that, due to the existence of brachypterous forms of C. vidua vidua in alpine regions ( Kühtreiber 1934; Aubert 1950), the criterion of the presence of reduced wing-pads in well-grown larvae cannot be used to separate male specimens of Zwicknia from those of C. vidua vidua . Moreover, topotypical specimens of C vidua vidua are micropterous (Dávid Murányi, pers. comm.).

1 In lateral view, the bristles of the pronotum are erect and unequal in length ( Figs. 17 and 18). The bristles of the anterior and posterior margin of the pronotum are mostly longer than those in the center ( Fig. 17). Head with several long, stiff and erect setae (Fig. 18). Upper margin of femur of posterior leg with a row of both long and short setae (the longest measuring more than half of the total width of the femur). Extension on margin of tergite 10 (prefiguring the adult epiproct) of male larvae rounded at apex in lateral view ( Fig. 19 ) and indented at apex in dorsal view. Wing-pads of forewing of full-grown female larvae with a triangular cubital cell (cf. Fig. 16).................................. Capnia vidua vidua (Alps and Prealps)

- In lateral view, the bristles covering the pronotum are either erect and about equal in length ( Figs. 24, 33 and 42) or else lie flat, are short and scarce ( Fig. 20). Head without long and stiff setae ( Figs. 21, 23, 32 and 41). Extension on margin of tergite 10 of male larvae truncated ( Figs. 25, 34, 43 and 49) or acuminated ( Fig. 22) at apex in lateral view......................... 2

2 In lateral view, the bristles covering the pronotum are short and lie flat against it ( Fig. 20). Upper margin of femur of posterior leg with a row of very short setae of unequal lengths (the longest not measuring more than one third of the total width of the femur). Wing-pads of well-grown male and female larvae always fully developed. Extension on margin of tergite 10 of male larvae acuminated at apex in lateral view ( Fig. 22). Wing-pads of forewing of full-grown female larvae with a triangular cubital cell (cf. Fig. 15 )........................................................ Capnia nigra (Alps and Prealps)

- In lateral view, the bristles covering the pronotum are about equal in length, dense and erect ( Figs. 24, 33 and 42)......................................................................................................3 ( Zwicknia )

3 Posterior margin of tergite 10 rounded, without pointed extension, in dorsal view ( Fig. 40). Wing-pads of well-grown larvae always fully developed ( Fig. 31). Wing-pads of forewing of full-grown female larvae with a quadrangular cubital cell (cf. Figs. 4 , 9 and 14).................................................................... 4 (female larvae of Zwicknia )

- Posterior margin of tergite 10 with pointed extension, in dorsal view ( Figs. 26, 35, 44 and 48). Pointed extension on margin of tergite 10 truncated at apex in lateral view ( Figs. 25, 34, 43 and 49). Wing-pads of well-grown larvae incompletely developed or only rudimentary, prefiguring micropterous ( Figs. 30 and 39) or brachypterous ( Fig. 48) adults. 6 (male larvae of Zwicknia )

4 Segments 3, 4 and 5 of maxillary palp densely covered with small setae ( Fig. 27). Bristles on margins of pronotum long, dense and erect ( Fig. 24). Abdominal tergites densely covered with long setae ( Fig. 29). Upper margin of femur of posterior leg with a row of both long and short setae (the longest measuring nearly half of the total width of the femur; Fig. 28).................................................................................................... Zwicknia ledoarei

- Segments 3, 4 and 5 of maxillary palp less densely covered with small setae ( Figs. 36 and 45). Bristles on margins of pronotum shorter ( Figs. 33 and 42). Setae on abdominal tergites shorter or less dense ( Figs. 38 and 47). Upper margin of femur of posterior leg with a row of shorter or less dense setae ( Figs. 37 and 46)................................................ 5

5 Setae on head short and dense ( Figs. 32 and 36). Bristles on margins of pronotum dense, short and erect ( Fig. 33). Upper margin of femur of posterior leg with a row of very sparse and short setae of unequal lengths (the longest not measuring more than one third of the total width of the femur; Fig. 37)................................................ Zwicknia bifrons

- Setae on head longer, but scarce and isolated ( Fig. 41). Bristles on margins of pronotum very short ( Fig. 42). Upper margin of femur of posterior leg with a row of compact, but short setae of unequal lengths (the longest not measuring more than one third of the total width of the femur; Fig. 46).................................................... Zwicknia westermanni

6 Pointed extension on margin of tergite 10 (prefiguring the adult epiproct) triangular in shape, with straight sides, in dorsal view ( Figs. 26 and 35), and truncated in lateral view ( Figs. 25 and 34). Wing-pads of well-grown larvae rudimentary, prefiguring micropterous adults ( Figs. 30 and 39). Setae on head short and dense ( Figs. 23, 32 and 36). Setae on margins of pronotum short, dense and erect ( Figs. 24 and 33)..................................................................... 7

- Pointed extension on margin of tergite 10 (prefiguring the adult epiproct) very long, conical in shape, with sinuous sides and blunt apex, in dorsal view ( Fig. 44), and very long and truncated, in lateral view ( Figs. 43 and 49). Wing-pads of well-grown larvae of medium length, prefiguring brachypterous adults ( Fig. 48). Segments 3, 4 and 5 of maxillary palp covered with few small setae ( Fig. 45). Setae on head longer, but scarce and isolated ( Fig. 41). Bristles on margins of pronotum very short ( Fig. 42)................................................................................. Zwicknia westermanni

7 Pointed extension on margin of tergite 10 (prefiguring the adult epiproct) with narrow base, in dorsal view ( Fig. 26). Segments 3, 4 and 5 of maxillary palp densely covered with small setae ( Fig. 27). Bristles on pronotum long and erect ( Fig. 24). Abdominal tergites covered with long and dense setae ( Fig. 29). Upper margin of femur of posterior leg with a row of both long and short setae (the longest measuring nearly half of the total width of the femur; Fig. 28)................. Zwicknia ledoarei Pointed extension on margin of tergite 10 (prefiguring the adult epiproct) with wide base, in dorsal view ( Fig. 35). Segments 3, 4 and 5 of maxillary palp less densely covered with small setae ( Fig. 36). Setae on head short and dense ( Figs. 32 and 36). Bristles on pronotum dense, short and erect ( Fig. 33). Upper margin of femur of posterior leg with a row of very sparse and short setae of unequal lengths (the longest not measuring more than one third of the total width of the femur; Fig. 37)................................................................................................... Zwicknia bifrons

Figures

FIGURE 4. Zwicknia ledoarei, adult female,forewing. Arrow pointing at quadrangular cubital cell.

FIGURE 15. Capnia nigra, adult female, forewing.Arrow pointingat triangular cubital cell.

FIGURE 19. Capnia vidua vidua, mature male larva, tergite 9, lateral view.

FIGURE 30. Zwicknia ledoarei, micropterousmale larva, wing-pads, dorsal view.