Dictyogenus nadigi, Reding, 2024

Reding, Jean-Paul G., 2024, Notes on the genus Dictyogenus Klapálek, 1904 (Plecoptera, Perlodidae) in the Austrian, Italian, Slovenian and Swiss Alps, with the description of six new species, Zootaxa 5397 (2), pp. 151-194 : 176-181

2.4 Dictyogenus nadigi sp. n.

urn:lsid:zoobank.org:act:F1562302-D210-4B66-887B-66B9E78373FA

( Figs. G.1–G . 16 )

Dictyogenus fontium : Nadig 1942:402; Aubert 1965:239; Consiglio 1967:44; Consiglio 1980:14; Lubini et al. 2012:212; Knispel & Lubini 2015:261; Fochetti 2020:382; Roesti 2021:138; Blattner et al. 2021:6

Adults. Body length of males 15–19 mm (n = 44); females 16–23 mm (n = 33). Adult males and females of D. nadigi sp. n. have both macropterous and brachypterous (Figs. G.6, G.16) populations, often occurring syntopically. Most are brachypterous; some macropterous. Head light brown. M-line not well-marked ( Fig. G.1 ). Pronotum light brown ( Fig. G.1 ). Yellow median band wide, extending from the anterior margin of the pronotum to its posterior margin, widening in its posterior margin ( Fig. G.1 ). Interocellar area with a large, yellow spot ( Fig. G.1 ). A tawny area on each side of the pronotum, with dark, sculpted rugosities ( Fig. G.1 ). Abdominal sterna pale brown, with typical dark, arch-like markings (Fig. G.6). Proximal part of tibiae with a dark band. Antennae and cerci blackish to dark brown.

Male terminalia. Tip of epiproct straight ( Figs. G.2 , G. 3 ). Lateral stylets with a small bulge on their proximal, inner side, and with straight margin on their distal, outer side ( Figs. G.2 , G. 3 ). Hemitergal lobes short and slender ( Fig. G.4 ).

Morphological affinities. Adult males of D. nadigi sp. n. are separable from those of topotypical D. fontium by their lateral stylets, which are straight on the distal (right) side in the former ( Figs. G.2 , G. 3 ), and concave in the latter ( Figs. C.2 , C. 3 , C.4).

Females. Subgenital plate short, with (Fig. G.5) or without median notch on its distal edge.

Mature nymphs. Length 13–26 mm (n = 97). Mature male and female nymphs with prefigured macropterism or brachypterism. Dimorphic setation is seen only between macropterous and brachypterous nymphs in both sexes. No sexually dimorphic setation, however, unlike in topotypical D. fontium specimens, between macropterous male and macropterous female nymphs, and also no dimorphic setation between brachypterous male and brachypterous female nymphs. No tuft of flexible mediodorsal occipital setae; only stiff mediodorsal occipital setae ( Fig. G.7 ). No setae on pronotum of macropterous male or female nymphal specimens (Fig. G.8). Meso- and metanotum of macropterous male and female nymphs without mediodorsal setation (Figs. G.8–G.10). No setae on pronotum of brachypterous male or female nymphal specimens; a small number of brachypterous male and female nymphs may have one or two very long setae on their pronotum, usually near the lower or upper edge. Meso- and metanotum of brachypterous male and female nymphs with sparse mediodorsal setation (Figs. G.11, G.12). Abdominal tergites of macropterous male and female nymphs without mediodorsal flexible setae and with only very few short intersegmental stiff setae ( Fig. G.13 ). Abdominal tergites of brachypterous male and female specimens with sparse, long mediodorsal flexible setae, interspersed with yellowish intersegmental stiff setae (Fig. G.14). Paraprocts, in ventral view, with up to seven spines per side, unevenly distributed between left and right (Fig. G.15). Mediodorsal setae on base of cerci compacted, but short, less than the width of the cercal segment. Stipe with very few spines distributed in a single row.

Morphological affinities. The nymphs of D. nadigi sp. n. are separable from those of topotypical D. fontium by the presence of flexible mediodorsal setae on the abdominal tergites of brachypterous specimens in the former (Fig. G.14), and their absence in the latter (Fig. C.15), and by the presence of mediodorsal setae on meso- and metanotum of macropterous female nymphs in topotypical D. fontium (Figs. C.11, C.12), and their absence in D. nadigi (Fig. G.9).

Type material. SWITZERLAND. Canton of Graub ̧nden. Road to Val Cluozza, spring, 1820 m, 46° 39’ 59.1304” N, 10° 06’ 45.6584” E, 13.09.2012, 1♁, leg. S. Knispel (holotype, MZL, CB-13265 , GBIFCH01217059 ) ; 13.09.2012, 1♁b, 2♀b, leg. S. Knispel (paratypes, MZL, CB-13265 , GBIFCH01217062 ) . Tschierv, Funtauna Grossa , 1840 m, 46° 36’ 37.50” N, 10° 20’ 03.40” E, 21.06.2018, 2♁b, leg. G. Vinçon ( MZL, paratypes, GBIFCH01217061 ) ; Il Fuorn Pass, Ova da Buffalora , 2100 m, 46° 39’ 26.5392” N, 10° 17’ 02.9004” E, 29.06.2009, 1♁, leg. G. Vinçon (paratype, MZL, GBIFCH01217063 ) . ITALY. Lombardy. Rivulet near Passo dello Stelvio , 2323 m, 46° 32’ 00.636” N, 10° 28’ 27.66” E, 2.8.2015, 2♁, 2♀, leg. W. Graf ( MZL, paratypes, GBIFCH01217060 ) .

Other material. ITALY. Lombardy. Rivulet near Passo dello Stelvio, 2323 m, 46° 32’ 00.636” N, 10° 28’ 27.66” E, 20.07.2008, 1♁, 1♀, 1L♁ . Passo dello Stelvio , torrente Braulio, 2300 m, 46° 32’ 19.878” N, 10° 25’ 05.9628” E, 23.7.1975, 3L, leg. C. Ravizza ( MZL, CB-18640 , GBIFCH00899377 ) . Valtellina. Foscagno , torrente, 2200 m, 46° 29’ 22.7292” N, 10° 13’ 37.452” E, 22.7.1975, 1♁b (epiproct detached), 1L, leg. C. Ravizza ( MZL, CB-18640 , GBIFCH00899364 ) . Passo di Gavia, Rio Gaviola , 2760 m, 46° 20’ 36.546” N, 10° 30’ 16.4268” E, 6.7.1988, 20♁, 20♀, leg. C. Ravizza ( MZL, CB-18640 , GBIFCH00899344 ) . Sondrio. Santa Caterina Valfurva, torrente dell’Alpe, 2400 m, 46° 22’ 43.7736” N, 10° 29’ 6.1584” E, 3.7.2011, 3♁b, leg. C. Ravizza ( MZL, CB-18640 , GBIFCH00899351 ) . SWITZERLAND. Road to Val Cluozza , spring, 1820 m, 46° 39’ 59.1304” N, 10° 06’ 45.6584” E, 16.6.2012, 2L ♀, leg. S. Knispel ( MZL CB-13265 ) ; Tschierv, Funtauna Grossa , 1840 m, 46° 36’ 37.50” N, 10° 20’ 03.40” E, 20.07.2006, 1♁, leg W. Graf ( GRA) ; Il Fuorn Pass, Ova da Buffalora , 2100 m, 46° 39’ 26.5392” N, 10° 17’ 02.9004” E, 29.06.2009, 5♁, 5♁b, 1♀, leg. G. Vinçon ( RED) ; Il Fuorn , brooklet 1, 1800 m, 46° 39’ 52.59” N, 10° 12’ 40.38” E, 24.5.1956, 2L♁, 2L ♀, 2L♁b, 2L♀b, leg. J. Aubert ( MZL, CB-13264 ) ; Il Fuorn , brooklet 2, 1800 m, 46° 39’ 46.56” N, 10° 12’ 40.88” E, 20.7.1949, 1♁b, 1♀b, leg. J. Aubert ( MZL, CB-13265 ) ; 16.5.1958, 1L♁b, 2L ♀b, leg. J. Aubert ( MZL, CB-13264 ) ; God sur Il Fuorn , brooklet 2, 1777 m, 46° 39’ 52.1472” N, 10° 12’ 14.7356” E, 1.6.2011, 1L♁; 2.4.2012, 1L♁, 1L ♀, leg. S. Knispel ( MZL, CB-13265 ) ; God Tamangur, Clemgia , 2140 m, 46° 40’ 42.2328” N, 10° 21’ 35.9784” E, 30.6.2013, 1L♀b, leg. V. Lubini ( MZL, CB-13265 ) ; Piz Macun, Aua da Zeznina , 2594 m, 46° 43’ 41.4624” N, 10° 08’ 11.5692” E, 31.7.2012, 3♁b, 1♀b, leg. V. Lubini ( MZL, CB-13265 ) ; Val dal Fuorn , spring, 1841 m, 46° 39’ 42.2568” N, 10° 13’ 00.2604” E, 17.6.2012, 1L♁b, leg. S. Knispel ( MZL, CB-13265 ) ; Campsut , spring, 1670 m, 46° 29’ 30.8688” N, 9° 28’ 23.988” E, 28.5.2005, 2L♁b, 1L♀b, leg. V. Lubini ( MZL, CB-13264 ) ; Il Fuorn, Muranzina , 1890 m, 46° 34’ 39.9936” N, 10° 26’ 23.3232” E, 11.6.1993, 3L♁b, 2L♀b; 3.9.1993, 1L♀b, leg. V. Lubini ( MZL, CB-13264 ) ; Jöriseen, Vereinatal , 2500 m, 46° 46’ 38.0964” N, 9° 58’ 21.7704” E, 5.7.2003, 2♁b, leg. L. Indermaur ( MZL, CB-13265 ) ; spring La Stretta, Val Mora , 2196 m, 46° 34’ 17.6448” N, 10° 20’ 10.6656” E, 29.6.2013, 2L♀b, leg. V. Lubini & R. Wüthrich ( MZL, CB-13265 ) ; Brook, Alp La Scherra , 2087 m, 46° 38’ 31.9236” N, 10° 11’ 43.5732” E, 6.9.2011, 3L ♀, leg. V. Lubini ( MZL, CB-13265 , GBIFCH00280133 , used for molecular studies).

Distribution and ecology. Rhaetian Alps: Swiss National Parc, Val M̧stair, Passo dello Stelvio ( Fig. J.2 ). The species occurs in high-altitude brooks and springs, from 1670 m up to 2760 m.

Adult flight period. June and July, with isolated specimens emerging in September.

Derivatio nominis. Dedicated to the Swiss entomologist Adolf Nadig (1910–2003), for his pioneering efforts in exploring the spring fauna of the Swiss National Park.

Figures

FIGURES A.1–A.3: general characteristics of adult Dictyogenus. A.1—head and pronotum of adult male (D. alpinum); A.2—vesicle on sternite VII of adult male; A.3—venation of forewing of Dictyogenus (annotations by Dr. Olivier Béthoux). Photo Bertrand Launay.

FIGURES A.16–A.18: general characteristics of nymphal Dictyogenus. A.16—exuvia of nymph (D. nadigi sp. n.); A.17— abdominal tergites of mature nymph, lateral view, showing the yellow stiff and bright flexible mediodorsal setae (D. nadigi sp. n.); A.18—abdominal tergite with stiff (s), flexible (f) and clothing (c) setae (D. nadigi sp. n.).

FIGURES I.2–I.7: Dictyogenus vinconi sp. n. I.2—adult female, head and pronotum; I.3—epiproct and lateral stylet of adult male; I.4—ventral lobe on sternite VII of adult male; I.5—hemitergal lobes of adult male; I.6—subgenital plate of adult female; I.7—subgenital plate of adult female.

FIGURES J.3: distribution maps of Dictyogenus. J.3—distribution map of Dictyogenus (topotypical D. fontium, D. nadigi sp. n., and D. padanum sp. n.) in alpine drainage basins.

FIGURES A.4–A.9: general characteristics nymphal Dictyogenus. A.4—separation of abdominal tergites I and II; A.5— lacinia with shoulder-like angle; A.6—prefigured ventral vesicle on sternite VII in mature male nymph, ventral view; A.7— nymph, row of stiff spines on occiput (dorsal view); A.8—female nymph, sternite VIII, ventral view; A.9—female nymph, sternite VIII, ventral view.

FIGURES B.7–B.12: nymphs of Dictyogenus alpinum. B.7—mediodorsal setation of nymph (head and pronotum); B.8— spines on paraprocts of nymph, in ventral view; B.9—mediodorsal setae on cerci; B.10—spines on stipe of nymph; B.11— mature female nymph, sternite 8, ventral view; B.12—mediodorsal setation on tergites of nymph.

FIGURES C.13–C.18: nymphs of Dictyogenus fontium (topotypical). C.13—tergites of macropterous female nymph (Val d’Anniviers); C.14—mesonotum, brachypterous male nymph (Agenetal); C.15—tergites, brachypterous male nymph (Arolla); C.16—spines on paraprocts of nymph, ventral view; C.17—cerci, mediodorsal setation; C.18—spines on stipe.