Adult specimens of mayflies were collected by using a sweep net in 2012 (Suppl. materials 1, 2). Specimens were collected among aerial swarms or from lower vegetation. The collected sample was placed in a plastic bag with a pad wetted in chloroform and stunned insects were finally preserved in ethanol. Mayfly nymphs were searched by using kick-net (mesh size 0,5 mm) in 2013. Layer photos were taken using an Olympus E520 digital camera attached to an Olympus SZX16 stereomicroscope. Digital photos were captured using the softwareDeep Focus v. 3.1 and Quick PHOTO CAMERA 2.3. Layer photos were finally combined with the program Combine ZP. Coordinates are given in WGS84 format.

Paraleptophlebia werneri is awestern Palaearctic species. Its range extends from the British Isles to the eastern side of Urals (Russia), and from northern Fennoscandia to the Alps (Bauernfeind and Soldán 2012). The species occurs in Norway (Johansen and Lunde 1993) and the Swedish records are from the northern provinces (Lycksele Lappmark, Pite Lappmark and Torne Lappmark, Engblom 2001). In his nationwide mayfly survey, Tiensuu (1939) reported only a single locality for P. werneri from Regio kuusamoensis: Kuusamo, W. Hellén leg., 1 male. No more specific locality or habitat information was given in that publication or found in Tiensuu’s otherwise detailed note books. It is likely however that the locality is currently on the Russian side of the border (Savolainen 2009). Another verified record is the one by Mauri Hirvenoja from Lapponia kemensis pars orientalis: Sodankylä, Mutenianjoki River, 30.6.1960, several swarming males (Savolainen 2009). One of us (ES) saw the sample and verified the identification in 1967. Regrettably, the Mutenianjoki river and the surrounding landscape were inundated and destroyed at the end of the 1960s due to the construction of the Lokka reservoir (200-400 square kilometers in area, depending on the water level). In addition to the above mentioned two sites, the species was reported from South Finland (Tavastia australis: Hausjärvi, [Hirvenoja 2002]). However, that record was based on small larvae and the habitat has since been destroyed (M. Hirvenoja, personal communication). In order to assess its range size and conservation status, P. werneri has been the focus of intensive searches during the last four decades in North Finland. Nevertheless, the species remained undetected until 2012. In the most recent national red-list assessment P. werneri was classified as RE (regionally extinct, Savolainen and Ilmonen 2010).

Adult males of Paraleptophlebia werneri are easily distinguished from other European species due to their characteristic genitalia and the shape of their gonopods (Fig. 2). See, e.g., Elliott and Humpesch (1983) and Bauernfeind and Soldán (2012) for the identification of adults; Macan (1979) and Bauernfeind and Humpesch (2001) for the identification of larvae.

a

b

c

d

Figure 2.

Paraleptophlebia werneri, collected from NE Lapland, Savukoski, Törmäoja.

a: adult males, habitus, lateral view, wing length ca. 5.5 mm  
b: male abdominal terminalia, lateral view  
c: male abdominal terminalia and forceps (gonopods), ventral view  
d: penis, ventral view  

According to literature records the larvae of this species dwell in several kinds of water bodies. Bauernfeind and Soldán (2012) state that P. werneri is an inhabitant of lowland streams and rivers characterized by abundance of submerged vegetation, usually in backwaters and ephemeral (summer dry) water bodies. Also Elliott and Humpesch (1983) note that the species thrives in lotic waters that lack water flow during summer. In the Swedish fell area the species has been caught from alpine headwater streams and even small ponds (Engblom 2001, E. Engblom, personal communication).

The first Finnish locality, the now vanished Mutenianjoki river, was a less than 10 m in breadth, eutrophic, slow flowing river with a muddy and stony bed. During summer time the river usually had low water level. The water was neutral or alkaline (pH over 7) and turbid due to abundance of algae. The river harbored aquatic insect larvae in great numbers. Mauri Hirvenoja collected his sample from the slow flowing outlet of the river. Lake Sompiojärvi, the source of the river, was shallow but well oxygenated (M. Hirvenoja, personal communication).

According to Bauernfeind and Soldán (2012) P. werneri is a univoltine, early summer species, whose adults emerge from April to June. The record from River Mutenianjoki is from the end of June. In northern Sweden, however, larvae have been collected at the end of July (E. Engblom, personal communication). The adult males reported here were caught in mid August.

Paraleptophlebia strandii is a North Palaearctic species with a wide range encompassing Fennoscandia and Russian Far East (Bauernfeind and Soldán 2012). The first Finnish record was given by Aro (1928), from three provinces in southern and northern Finland. According to Savolainen (2009) the species is absent from western and southwestern Finland and has been recorded from eastern and northern Finland, including northernmost Lapland.

The natural historyand occurrence of P. strandii are hitherto poorly known. There are scanty notes in the literature (see Bauernfeind and Soldán 2012), and according to Tiensuu (1935) the species favors small forest brooks with a slow current. In Finland the species is associated with running waters, especially small streams with aquatic mosses and vascular plants (Savolainen 2009). The life cycle of the species is unknown but it may be of the univoltine summer type (Bauernfeind and Soldán 2012).

In the present work were report P. strandii from boreal aapamires. These new observations are significant, because the notion of the species as a lotic one is challenged. Based on earlier records this species occurs in running water habitats with high oxygen levels. Our new records indicate that P. strandii is a common inhabitant of northern aapamires and that the species may be locally abundant. It may be assumed that P. strandii overwinters as an egg. Due to flowing of groundwater and thick snow cover, the flarks and pools in aapamires may retain some free water during snow covered periods (Koutaniemi and Seppälä 1986, Seppälä and Koutaniemi 1985), thus enabling the survival of the eggs. On the other hand, it has been noted that eggs of other mayfly species such as Baetis macani and B. bundyae may tolerate freezing (Giberson et al. 2007, Drotz et al. 2012).