Dolerus incisus Goulet, 1986

Liston, Andrew, Mutanen, Marko, Heidemaa, Mikk, Blank, Stephan M., Kiljunen, Niina, Taeger, Andreas, Viitasaari, Matti, Vikberg, Veli, Wutke, Saskia & Prous, Marko, 2022, Taxonomy and nomenclature of some Fennoscandian Sawflies, with descriptions of two new species (Hymenoptera, Symphyta), Deutsche Entomologische Zeitschrift 69 (2), pp. 151-218 : 151

Dolerus incisus Goulet, 1986

Fig. 20A-C

Notes.

Finland: Regio kuusamoensis, Kuusamo Siikauopaja, YKJ grid coordinates: 7362:3612 [66.334°N, 29.511°E], 2♀ (ZMUO.035155, ZMUO.035156), 12.06.2018. 1♀ (ZMUO.045265), 20.06.2020. All specimens leg. M. Mutanen. ZMUO.

First record in the Palaearctic. Recorded previously only in boreal North America: Alaska, Alberta, Yukon, and North West Territories ( Goulet 1986). The genetic and morphological affinity of D. incisus to D. junci and D. yukonensis suggests that the host plant of D. incisus is also a species of Equisetum ( Goulet 1986). The habitat in Finland is a shallow oxbow lake (meander) of the Oulanka river with plenty of Equisetum fluviatile , which is also the host of D. junci . This habitat matches perfectly with that given for D. incisus in North America by Goulet (1986). Several other Dolerus species occur syntopically, including the closely related D. junci Stephens (= D. cothurnatus auct., see above). The melanic form of D. incisus is recorded from Finland (all three are females, see above, Fig. 20A ) and Norway (Heimdalsmunnen, alt 1150 m, leg. E. Heibo, CEH). Melanic females of D. subarcticus (recorded from Norway and Kamtschatka, see under D. subarcticus ) can be distinguished by their postocellar furrows, the sawsheath (valvula 3) shape, and its apical setation (Fig. 20B ). Melanic males can be separated most reliably by their penis valves (Fig. 20C , 20D ). Only the melanic colour form of D. incisus has so far been recognized from Fennoscandian countries, whereas in Canada and the USA both the black color form and a form with red-banded abdomen and partly reddish legs are known. We studied paratypes of D. incisus : 2♀, 2♂, some of them dissected, CNC.

Figures

Figure 20. Dolerus incisus Goulet, 1986. A. Dorsal habitus ♀; B. Valvula 3 dorsal; C. Penis valve; D. Dolerus subarcticus Hellen, 1956, penis valve.