Dictyogenus, Klapalek, 1904

Reding, Jean-Paul G., Launay, Bertrand, Doaré, Jacques Le, Ruffoni, Alexandre & Vinçon, Gilles, 2019, Two New Species Of Dictyogenus Klapálek, 1904 (Plecoptera: Perlodidae) From The Jura Mountains Of France And Switzerland, And From The French Vercors And Chartreuse Massifs, Illiesia 15 (2), pp. 27-64 : 51-52

Morphological key to mature larvae) (> 8 mm) of Dictyogenus

The larva of Dictyogenus fontium was first described by Kühtreiber (1931), but erroneously listed under the name of D. alpinum , as the same author later (1934) recognizes when providing descriptions of both species. The single major criterion used by him for separating both species hinges on the presence ( D. alpinum ) or absence ( D. fontium ) of a row of erect medio-dorsal setae on the pronotum. This criterion, however, only separates the larvae of the Dictyogenus fontium species complex from the group composed of D. alpinum , D. jurassicum and D. muranyii . As can be inferred from the descriptions of the two new species in the present contribution, the setation patterns of the medio-dorsal row of setae on the pronotum as well as on the mesonotum, metanotum and abdominal terga in the genus Dictyogenus are far more complex. We have also noted that early instar larvae continue to undergo important morphological changes prior to reaching 8 mm body length. Prior to this size they are impossible to identify to species.

1 Pronotum with medio-dorsal setae ( Figs. 13 , 40, 41 , 65, 71 ). Postero-dorsal edge of the femora and tibiae with a fringe of dense silky hair setae ( Figs. 15 , 42 , 70 ) …………………… 2

1’ Pronotum devoid of medio-dorsal setae ( Figs. 85, 86 ). Postero-dorsal edge of femora and tibiae with a fringe of sparse silky hair setae ( Fig. 87 ) ……….. Dictyogenus fontium species complex (not keyed)

2 Medio-dorsal setae on pronotum, mesonotum, metanotum and abdominal terga very long, erect, dense and continuous, extending to the occiput of the head ( Figs. 65, 71 ). Interocellar area with a wide yellow patch, trident-shaped ( Figs. 62 , 63 ). Lateral ocelli with circum-ocellar yellow patch ( Fig. 63 ). A large, elliptical, yellow patch above each lateral ocellus ( Figs. 62 , 63 ). M-line curved and well visible ( Figs. 62 , 63 ). Upper margin of stipes with numerous (7- 25) spines arranged in several rows ( Fig. 69 ). Pronotum markedly trapezoidal with straight sides ( Fig. 63 ). Paragenital plates, in ventral view, with numerous spines (3-20, average 15) per side ( Fig. 68 ). Cerci with medio-dorsal row of swimming hairs of dense and compact, twice as long as the width of the cercus ( Fig. 67 ) …………………………... Dictyogenus alpinum

2’ Medio-dorsal setae on pronotum, mesonotum, metanotum and abdominal terga less dense, often with interruptions ( Figs. 13, 14, 15 , 40, 41 ). Postero-medial part of head without setae, but only with a few long spines ( Figs. 40, 41 ). Upper margin of stipes with fewer spines (1- 13) arranged in a single row ( Fig. 45 ). Paragenital plates, in ventral view, with fewer, generally unpaired, spines or else devoid of spines ( Figs. 17 , 44 ). Cerci with medio-dorsal row of swimming-hairs only slightly longer than the width of the cercus ( Figs. 16 , 43 ) …………………………………… 3

3 Medio-dorsal setae on pronotum short and scattered, arranged as two loosely demarcated rows ( Fig. 13 ). Interocellar area pale yellow, narrow with well demarcated contours ( Figs. 10 and 11 ). Pronotum ovoid in shape ( Fig. 11 ). Endemic to the Jura Mountains ...................................... Dictyogenus jurassicum

3’ Medio-dorsal setae on pronotum longer, but dense, sometimes covering only its lower half ( Figs. 40, 41 ). Interocellar area with wide, pale yellow, keyhole-shaped area ( Fig. 37 , 38 ).

Pronotum nearly trapezoidal in shape ( Figs. 37 , 39 ). Endemic to the Chartreuse and Vercors massifs ………. Dictyogenus muranyii

Figures

Figs. 11-19. Dictyogenus jurassicum sp. n., larva. Karstic spring of Côte au Bouvier, near Soubey, canton of Jura, Switzerland. All images credited to J.-P.G. Reding. 11. Head and pronotum, dorsal view. 12. Lacinia. 13. Pronotum, dorso-lateral view. 14. Mesonotum and metanotum, dorso-lateral view. 15. Abdominal tergites, lateral view. 16. Medio-dorsal row of setae on base of cerci, lateral view. 17. Paragenital lobes, ventral view. 18. Tergites 5, 6 and 7, dorsal view. 19. Separation of tergites and sternites, lateral view.

Figs. 38-45. Dictyogenus muranyii sp. n., larva. 38. Head, pronotum and mesonotum, dorsal view. Karstic spring of Brudour, Drôme dpt, France. Photo B. Launay. 39. Head, pronotum, dorsal view. Karstic spring of Brudour, Drôme dpt, France. Photo A. Ruffoni. 40. Head, pronotum, mesonotum and metanotum, lateral view. Karstic spring of Bruyant, Isère dpt, France. Photo A. Ruffoni. 41. Pronotum, lateral view. Karstic spring of Bruyant, Isère dpt, France. Photo J.-P.G. Reding. 42. Abdominal segments, lateral view. Karstic

Figs. 63-71. Dictyogenus alpinum, larva. 63. Head and pronotum. Rioufroid, Lus-la-Croix-Haute, Drôme dpt, France. Photo A. Ruffoni. 64. Lacinia. Rioufroid, Lus-la-Croix-Haute, Drôme dpt, France. Photo A. Ruffoni. 65. Pronotum, mesonotum and metanotum, lateral view. Vorz river, Belledonne massif, Isère dpt, France. Photo B. Launay. 66. Detail of head. Rioufroid, Lus-la-Croix-Haute, Drôme dpt, France. Photo A. Ruffoni. 67. Medio-dorsal setae on cerci. Riau du Gros Mont, Les Planeys, canton of Fribourg, Switzerland. Photo J.- P.G. Reding. 68. Paragenital plates, ventral view. Riau du Gros Mont, Les Planeys, canton of Fribourg, Switzerland. Photo J.-P.G. Reding. 69. Stipe. Vorz river, Belledonne massif, Isère dpt, France. Photo B. Launay. 70. Femur and tibia of hind leg, lateral view. Riau du Gros Mont, Les Planeys, canton of Fribourg,

Figs. 85-87. Dictyogenus fontium species complex, larva. 85. Pronotum, lateral view. Inner-alpine upper Isère Valley. Col de l’Iseran, Savoie dpt, France. Photo Alexandre Ruffoni. 86. Pronotum, lateral view. Inneralpine upper Swiss Rhône valley, Anniviers Valley, canton of Valais, Switzerland. Photo J.-P.G. Reding. 87. Hind leg, lateral view. Inner-alpine upper Swiss Rhône valley, Anniviers Valley, canton of Valais, Switzerland. Photo J.-P.G. Reding.

Fig. 62. Dictyogenus alpinum, larva. Rioufroid, Lus-la-Croix-Haute, Drôme dpt, France. Photo A. Ruffoni.

Fig. 10. Dictyogenus jurassicum sp. n., larva. Spring of River Doubs, Mouthe, Doubs dpt, France. Photo A. Ruffoni.

Fig. 37. Dictyogenus muranyii sp. n., larva. Karstic spring of Brudour, Drôme dpt, France. Photo A. Ruffoni.