Arcynopteryx dichroa

Arcynopteryx dichroa (McLachlan, 1872) = Arcynopteryx compacta (McLachlan, 1872) in Lavandier (1979). TAXO / DIFF. A. dichroa was originally described in 1872 under the name Dictyopteryx dichroa (McLachlan, 1872). In 1912, Klapalek reviewed the genus Arcynopteryx Klapálek, 1904 and defined A. compacta (McLachlan, 1872) as the type species of this genus (Klapálek, 1912), a genus currently valid. However, he made a mistake by using a plate representing A. dichroa instead of A. compacta (Teslenko 2012). In addition, A. compacta is currently not included in the genus Arcynopteryx but in the genus Skwala Ricker, 1943 under the name S. compacta (McLachlan, 1872). Finally, the type species of the genus Arcynopteryx is now A. dichroa (Teslenko 2012). For these reasons, the individuals identified as A. compacta in Lavandier (1979), before Klapalek’s mistake was highlighted in Teslenko (2012), should correspond to A. dichroa, a species that we also collected in 2022. We thus corrected A. compacta for A. dichroa in Lavandier’s dataset (Table 2). DIST. In France, this species has a relict status (Theissinger et al. 2013), only present in the Pyrenean mountain, whereas it is much more common in northern Europe (DeWalt et al. 2026; GBIF 2026). It is probably one of the most sensitive species within the Estaragne Plecoptera community, restricted to the coldest reaches up to 2000 m a. s. l. in both the main river and its tributaries. In 2022, larvae were captured and identified at the three campaigns (Fig. 2 C), while adults were less frequently observed.