New and poorly known Palaearctic fungus gnats (Diptera, Sciaroidea)

Abstract Background Fungus gnats (Sciaroidea) are a globally species rich group of lower Diptera. In Europe, Fennoscandian peninsula in particular holds a notable diversity, ca. 1000 species, of which 10 % are still unnamed. Fungus gnats are predominantly terrestrial insects, but some species dwell in wetland habitats. New information Eight new fungus gnat species, belonging to the families Keroplatidae (Orfelia boreoalpina Salmela sp.n.) and Mycetophilidae (Sciophila holopaineni Salmela sp.n., S. curvata Salmela sp.n., Boletina sasakawai Salmela & Kolcsár sp.n., B. norokorpii Salmela & Kolcsár sp.n., Phronia sompio Salmela sp.n., P. reducta Salmela sp.n., P. prolongata Salmela sp.n.), are described. Four of the species are known from Fennoscandia only whilst two are supposed to have boreo-alpine disjunct ranges, i.e. having populations in Fennoscandia and the Central European Alps. One of the species probably has a boreal range (Finnish Lapland and Central Siberia). Type material of Boletina curta Sasakawa & Kimura from Japan was found to consist of two species, and a further species close to these taxa is described from Finland. Phronia elegantula Hackman is redescribed and reported for the first time from Norway. DNA barcodes are provided for the first time for five species.


Introduction
Sciaroidea are lower Diptera traditionally classified to the infraorder Nematocera, threadhorned flies (Amorim and Yeates 2006). Nematocera, however, is a paraphyletic group, and Sciaroidea are currently treated within Neodiptera, a monophyletic clade including Bibionomorpha and all brachyceran fly families (Wiegmann et al. 2011). Sciaroidea includes fungus gnats in the broadest sense (Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae, Lygistorrhinidae, Mycetophilidae), black-winged fungus gnats (Sciaridae) and gall midges (Cecidomyiidae) (Ševčík et al. 2016b). In this paper only fungus gnats are included. Fungus gnats are mostly associated with forests, and their larvae dwell in fungal fruiting bodies, dead wood and soil; some species are associated with wetlands such as fens (Økland 1999, Søli et al. 2000, Jakovlev 2011, Salmela and Suuronen 2014. Fungus gnats are a highly diverse group of flies, having over 5000 known species globally (Pape et al. 2009), and but this number is expected to rise (see e.g. Borkent andWheeler 2012, Kurina andHippa 2015). In Europe fungus gnats probably display an anomalous gradient of species richness, that is, the number of species correlates positively with latitude . The northern boreal zone is probably the hot-spot of fungus gnat species richness (Kjaerandsen et al. 2007), and the Fennoscandian peninsula (Norway, Sweden, Finland, Kola peninsula and Russian Karelia) in total harbours about 1000 species, of which ca. 100 still await formal description (Kjaerandsen 2016).
DNA barcoding has become a standard procedure in biodiversity surveys and taxonomic studies (e.g. Stur and Borkent 2014, Nielsen et al. 2015. The method is based on the observation that a fragment of the mtDNA gene COI in animals possess variation that is suitable for separating species (Hebert et al. 2003). One of the advantages of DNA barcoding has been the detection of cryptic species, that mostly consists of taxa that were previously overlooked (Nielsen et al. 2015). DNA barcoding has been used successfully in fungus gnat taxonomy , Jürgenstein et al. 2015, Ševčík et al. 2016a, and in the vast majority of cases the sequence variation in the COI is in accordance with morphological variation. In order to advance fungus gnat taxonomy, researchers in Norway, Finland and Russian Karelia have recently assembled a reference library including almost 1600 sequences belonging to 540 species or operational taxonomic units (J. Kjaerandsen, et al. in prep.). In the present paper however, DNA barcodes are not analysed in detail and are instead used for comparative purposes. Nevertheless, the barcodes provided here should be helpful in observing these rare taxa in the future.
The new species described here belong to the genera Orfelia Costa, Sciophila Meigen, Boletina Staeger and Phronia Winnertz. Orfelia is a keroplatid genus with 36 Holarctic species, of which 25 are known from the Palaearctic region (Evenhuis 2006, Kurina andJürgenstein 2013). The genus has not been revised and keys have been produced only for species present in Great Britain (Hutson et al. 1980) and Russia (Zaitzev 1994). Larvae of the genus are saproxylic (Zaitzev 1994). Sciophila is a mycetophilid genus with 98 Holarctic species, of which 70 are Palaearctic (Zaitzev 1982, Pape andThompson 2013). The genus was revised by Zaitzev 1982, and 18 new species descriptions have since followed (e.g. Zaitzev 1994, Polevoi 2001. Sciophila larvae are mostly associated with fungal fruiting bodies, especially polypores, and most likely are spore-feeding (Jakovlev 2011) or may develop internally in fungus tissue (Zaitzev 1982). Three Boletina species are figured here and discussed; a review on the taxonomic status and ecology of the Holarctic species of the genus was recently provided . The genus Phronia is rich in species, having 112 and 97 named taxa in the Holarctic and Palaearctic regions, respectively (Gagné 1975, Jakovlev and Polevoi 2009, Ševčík 2009, Pape and Thompson 2013. The first comprehensive treatment of the European Phronia was published by Dziedzicki 1889, a rare example of a 19th century lower Diptera publication that is still useful today. Hackman 1970 published an important paper on the eastern Fennoscandian species and North American species were revised by Gagné 1975. Plassmann 1977 provided a key to the Palaearctic fauna, but the key relies heavily on body coloration characters that are known to vary and are hard to interpret. In addition, figures in Plassmann's publication were mostly copied from older sources and are of rather poor quality. Later Zaitzev 2003 compiled a key for Russian species and provided illustrations of male genitalia. These illustrations, despite their good quality, depict mostly only one view per species (most often the hypopygium from the ventral view). In the identification of Phronia, however, several characters need to be seen, such as the aedeagus and gonostylus from a variety of angles (see e.g. Chandler 1992, Kurina 2008, Jakovlev and Polevoi 2009). Although the genus Phronia is in urgent need of revision we describe three new species here. This is because the new taxa can be easily separated from the closely related species based ondifferences in the male hypopygium and DNA barcodes. Phronia larvae build cases and live upon various saproxylic substrates, but some species are observed from soil (Jakovlev 2011).

Materials and methods
Most of the specimens studied were collected from Finland, mainly by using Malaise traps. Ethylene glycol was first used in the traps as a preservative and later the material was stored in 70 % ethanol. The morphological terminology used here follows (Søli 1997) and wing venation (Amorim and Rindal 2007). Terminology of Sciophila male hypopygium was adopted and slightly modified from (Kurina 2004 Images of male hypopygia were taken using an Olympus SZ61 stereomicroscope equipped with a Canon 650D camera and a LM Digital SLR Adapter. Habitus photos of the new Orfelia species were taken by using Olympus E520 digital camera, attached to an Olympus SZX16 stereomicroscope. Digital photos were captured using the programmes Deep Focus 3.1 and Quick PHOTO CAMERA 2.3. Extended depth of field photos were reconstructed using the software Combine ZP and were finalized with the use of Adobe Photoshop CS4. The maps were drawn by using SimppleMappr program (http://www.simplemappr.net/).
A 658 bp fragment of mitochondrial protein-encoding cytochrome c oxidase subunit I (COI) was sequenced from a total of 10 Sciaroidea specimens. Legs or 2-3 abdominal segments of the specimens were placed in 96% ethanol in a 96-well lysis microplate and dispatched to the Canadian Centre for DNA Barcoding, Biodiversity Institute of Ontario where DNA was extracted and sequenced using standard protocols and primers (deWaard et al. 2008). The fragment was successfully amplified for five taxa. The new sequences are deposited in GenBank under accession numbers KY062990-KY062993, KY200862-KY200865 and are also available below in the systematic part.
Barcodes of the Finnish specimens (all 658 bp in length, with no unambiguous bases) were submitted to the BOLD (Ratnasingham and Hebert 2007) identification engine (http:// v4.boldsystems.org/index.php/IDS_OpenIdEngine) in order to search for conspecific taxa and to assess the COI divergence between the new species and the taxa available in the BOLD database. We used "current database" and "All Barcode Records on BOLD" as options in the queries. The queries were made during October 2016 and at that time the BOLD database held 4,708,558 sequences (with a minimum sequence length of 500 bp), of which 46206 belonged to the family Mycetophilidae and 3665 to the Keroplatidae. Genetic similarities presented here are based on K2P distances and were calculated by the BOLD identification engine.

Description
Male. Head bicolored, vertex with a triangular dark area, laterally yellowish brown ( Fig.  1a, b, c). Three ocelli in shallow triangular arrangement, median ocellus smaller than laterals. Vertex covered by short black setae. Clypeus short, yellowish brown. Palpi pale, bearing both light and dark setae. Length ratio of palpal segments 3-5: 3:4=1.2, 4:5=0.67. Penultimate segment 2.25 times as long as wide, last segment 3.86 times as long as wide. Antennae dark brown, flagellomeres bearing dark sensilla that are shorter than width of respective flagellomere. First flagellomere widest apically, its length:width ratio 1.26 (width measured from the apex of the flagellomere). Other flagellomeres quadratic, slightly shorter than wide, except apical one that is elongated and bearing apical papilla; length:width ratios of fourth and last flagellomeres 0.9 and 1.91, respectively (Fig. 1b).
Scutum yellowish with three longitudinal brown stripes; median stripe consisting of two stripes that are largely merged, a narrow anterior gap between the stripes is present (Fig. 1b, c). Dark setae on scutum are present. Pleural sclerites of thorax light brown in colour, all bare except scutellum that has a dense row of setae along posterior margin. Halter light brown with dark setae.
Wings yellowish, with a faint subapical dark band extending from C to M2. Veins dark brown except bm-cu and bRs that are lighter. Veins R1 and bCuA with dorsal setae, R5 setose both ventrally and dorsally. Sc ending in C before bRs. R4 very short, about 0.12 times longer than apical portion of R5. Wing length 4.1 mm.
Coxae yellowish brown -brown, bearing short dark setae, legs yellowish. Ratio of femur to tibia for fore, mid and hind legs: 0.79, 0.68, 0.63. Ratio of tibia to basitarsus for fore, mid and hind legs: 1.67, 1.0, 1.0. Anterior spur of mid-tarsus about 0.5 times longer than posterior spur.
Female.The paratype female is lacking all legs except right fore leg and right hind femur. The specimen is slightly paler than the holotype male. The specimen may be somewhat teneral or it has bleached in the Malaise trap or later in the ethanol. Otherwise the specimen is very similar to the holotype. Antennal flagellomeres, except first and last, are wider than long (length:width ratio of 4th segment is 0.78). Cerci short, apically truncated, gonocoxite 8 short and rounded. Wing length 3.9 mm.

Diagnosis
The new species is characterised by the short and dark antennae, a yellow scutum with contrasting scutellar stripes, brown pleural sclerites of the thorax, brown, unicolorous a b c d Figure 2.

Etymology
The name of the new species refers to its putative boreo-alpine, disjunct range in Europe. The name is a noun in apposition.

Distribution
The new species has been observed from eastern Finnish Lapland, the north boreal ecoregion, and from Germany, Bavaria (see Geiger et al. 2016). It is likely that O. boreoalpina sp.n. has a disjunct European range, having populations in the northern Fennoscandia and the Central European mountains (Fig. 3).

Ecology
The Finnish sampling site was a herb-rich meadow, harbouring vascular plants such as Bistorta vivipara and Trollius europaeus, and is probably flooded during snowmelt in spring. The meadow is surrounded by pine (Pinus sylvestris) dominated boreal forest. Bavarian site is a conifer-dominated mountain forest (Geiger et al. 2016)

Taxon discussion
The new species is rather distant to all other Holarctic species, but it may be closest to O. nigricornis and O. subnigricornis (see below). If using the key provided by Hutson et Collecting sites of the new fungus gnat species Orfelia boreoalpina Salmela sp.n., Phronia reducta Salmela sp.n. and P. prolongata Salmela sp.n.
al. 1980, (species known from Great Britain), the species should either have a largely black or orange thorax, including the pleura, but O. boreoalpina sp.n. has an orange scutum and brown pleura, thus dropping out already in the first couplet. In the key provided by Zaitzev 1994 (Russian species), the new species keys in the first couplet (mesonotum yellow with broad longitudinal stripes). In the couplets 2-5 there are three options, and the new species comes closest to O. nigricornis, that has elongated palpal segments and one pointed outgrowth on the dorsal side of gonocoxites. Orfelia nigricornis, however, has a tuft of setae on the apex of dorsal lobe of the gonostylus while O. boreoalpina has only two dark setae. Other more or less similar species are 1) O. subnigricornis, that is characterized by the yellow scape and pedicel and median flagellomeres that are 1.4 times longer than wide (Zaitzev and Menzel 1996)  Fore coxae light brown, mid and hind coxae dark brown, with pale setae, trochanters dark-brown. Legs yellowish brown, femora basoventrally darkened; apices of mid and hind coxae infuscated, the latter more clearly so. Setae on femora mostly dark, tibial and tarsal setae dark. Length ratio of femur to tibia for fore, mid and hind legs: 0.93, 1.03, 0.89. Length ratio of tibia to basitarsus for fore, mid and hind legs: 1.36, 1.57, 1.89. Anteroapical depressed area of the fore tibia with two rows of pale setae, proximal row curved with ca. 17 setae and distal row almost straight with ca. 20 setae. Ratio of apical width of tibia:length of longest tibial spur for fore, mid and hind legs: 0.52, 0.33, 0.33.

Diagnosis
This is a very dark species with the head, antennae, thorax, and abdomen black or dark brown. The 9th tergite is apically rounded. The ventral lobe of the gonostylus has a prominent apical outgrowth. The aedeagus is about as long as the parameres with the apex truncated. The parameres are rather thin with their apices contorted.

Etymology
The new species is named after Mr. Tuomas Holopainen, the founder, songwriter and keyboardist of a Finnish metal band, "Nightwish". The name is a genitive.

Distribution
The new species is so far known only from eastern Finnish Lapland, the north boreal ecoregion (Fig. 5).

Ecology
The type locality in Törmäoja Conservation Area was a sloping birch forest in a river canyon, close to a spring brook.

Taxon discussion
The new species seems to be rather distant from the known Holarctic species of Sciophila. The number of large setae on the small median appendage of gonostylus is varying, it may be two or three, thus making the use of Zaitzev's (Zaitzev 1982) key problematic. If two setae, the new species comes closest to S. impar Johannsen, a species that shares some traits with the new species (e.g. smoothly rounded distal edge of 9th tergite, aedeagus with a blunt apex), but is otherwise very different, having e.g. a high number of comb-like megasetae on the large median lobe of the gonostylus (63-65 vs. 19 in S. holopaineni sp.n.). If three setae, the species runs to the couplet 79 and thereafter to 95, 99, 109 and finally to 114, but the new species does not fit either S. kashmirensis Zaitzev or S. stackelbergi Zaitzev. Holotype male had two and three setae, paratype male had two in both gonostyli.
We were not able to find any notes in the literature on the presence of a sensory field at the base of scape among Sciophila. JS checked a few specimens in his collection (JES), and the character was present in S. buxtoni Freeman, S. curvata sp.n., Leptomorphus forcipatus Landrock, Polylepta borealis Lundström and Allocotocera pulchella (Curtis), but it was absent among Anaclileia dziedzickii (Landrock). In Acnemia trifida Zaitzev there was an ventroapical sensory field at the scape, with hyaline cover. It is possible, that this trait is symplesiomorphic (an ancestral character or trait state shared by two or more taxa) amongst Sciophilinae and is lost in some genera.  Abdominal tergites and sternites dark brown, covered by pale setae. 9th tergite triangular, apex pointed (Fig. 6a). Gonocoxal apodeme not prominent. Dorsal lobe of gonostylus narrow, finger-like, with a strong apical spine (Fig. 6b, c, e); large median appendage of gonostylus with 18 comb-like megasetae arranged in a two-serial row (Fig. 6d). Small median appendage of gonostylus with three long setae (Fig. 6d). Ventral lobe of gonostylus prominent, hump-backed in shape; two long basal setae not well separated from other setae of the lobe (Fig. 6c, d, e). Aedeagus bifid, about as long as parameres; parameres strongly curved (Fig. 6b, f).

Diagnosis
The new species is characterised by the presence of three setae on the small median lobe of the gonostylus, very narrow dorsal lobe of the gonostylus and strongly curved parameres. The new species is closest to S. californiensis Zaitzev; the 9th tergite of the latter species is medially constricted, in the former the outline of the 9th tergite is triangular.

Etymology
The name of the new species (curvata Latin, curved, an adjective) refers to the curved parameres of the male hypopygium.

Distribution
The type locality of the new species is from the Pyhä-Luosto National Park in central Finnish Lapland.

Ecology
The trapping site was a herb-rich bed of an intermittent brook, surrounded by an oldgrowth boreal forest.

Taxon discussion
The new species is most likely close to S. californiensis, because they share the following characters: the small median lobe of the gonostylus has three prominent setae and a narrow dorsal lobe. The new species, however, differs from S. californiensis by having a triangular 9th tergite (with a median constriction in S. californiensis) and having 18 comb-like megasetae (48 in S. californiensis). Although not mentioned in the description and improperly figured (Zaitzev 1982
Boletina curta is probably on the wing early in the season: collecting dates of the holotype and all paratypes (except Yoshino, the holotype of. B. sasakawai sp.n., see below) range between April 27 and May 3. However, Russian specimens reported by Zaitzev (1994) were collected in autumn (September 21).

Taxon discussion
Boletina curta was described from Honshu, the main island of Japan (Sasakawa and Kimura 1974). The type material consists of the holotype male, collected from Mt. Hiei, and paratypes collected from four other localities (in addition, an allotype female from a further site). Two of these paratypes were studied by the authors, and the paratype from the type locality was found to be conspecific with B. curta. This paratype, despite its explicit labeling, was not mentioned in the original description (Sasakawa and Kimura 1974). The second paratype, collected from Yoshino, does not fit to the concept of B. curta, and is here described as a new species (see below B. sasakawai sp.n.).

Diagnosis
A large species with a vaguely infuscated wing apex, abdominal tergites 2-4 laterally yellowish and relatively long first flagellar segment (about 4-times the length of the pedicel). The ventral lobe of gonostylus bare, sinuous; in the closely related B. curta it is curved and bearing two stout setae. The apices of parameres with a conspicuous pair of horn-like outgrowths.

Etymology
The new species is named after Dr. Mitsuhiro Sasakawa, Japanese entomologist and the collector of the holotype. The name is a genitive.

Distribution
Known only from the type locality (Yoshino in Japan). The holotype male was collected at the end of October.

Etymology
The new species is named after Dr. Yrjö Norokorpi, Finnish forest researcher and former area manager at Parks & Wildlife Finland. The name is a genitive.

Distribution
So far known from SW Finnish Lapland only (Fig. 5).

Ecology
The Finnish trapping site was an old-growth boreal forest characterised by vascular plants typical for base-rich soils, such as Paris quadrifolia and Calypso bulbosa.

Taxon discussion
The Coxae yellow, bearing dark setae, legs yellowish. Length ratio of femur to tibia for fore, mid and hind legs: 1.02, 1.0, 0.84. Length ratio of tibia to basitarsus for fore, mid and hind legs: 1.28, 1.6, 1.63. Anteroapical depressed area of the fore tibia ovate, having ca. 20 light setae arranged in a curved row. Ratio of apical width of tibia:length of longest tibial spur for fore, mid and hind legs: 0.37, 0.30, 0.29.

a b
c d e f Figure 10.

Diagnosis
A small species that is different from the known member of the genus. The male hypopygium has the following diagnostic characters: the ventroapical margin of the gonocoxites has a deep notch; the mesial projection of the gonostylus lacks comb-like structures but bears a prominent finger-like projection and a rounded, hyaline protrusion; the aedeagal complex is about as long as broad and is apically notched.

Etymology
The name of the new species refers to the old Forest Sami name of the region, Sompio, meaning large area bordered by aapamires. The biogeographical province of Lapponia kemensis pars orientalis, abbreviated as Lkor, is in Finnish "Sompion Lappi". The name is a noun in apposition.

Distribution
The species has been collected so far from three localities, all of these from eastern Finnish Lapland close to the Russian border. In fact, all of the collecting sites belong to the River Tuuloma catchment area east of the Maanselkä divide, so the waters finally flow to the Barents Sea in Russia.

Ecology
Collecting sites are small waterbodies (spring-fed headwater streams, spring brooks) surrounded by old-growth boreal forests.

Taxon discussion
The new species stands apart from all other Holarctic members of the genus. Barcoding of the holotype and paratypes failed.

Diagnosis
The new species is close of P. braueri Dziedzicki but differs in the following features; the apices of the parameres are non-setose (the setae here are long in P. braueri), the internal outgrowth of the ventral lobe of the gonostylus is curved and apically notched (not curved or notched in P. braueri), and the ventral lobe of the gonostylus also has a narrow club-like basal projection (wedge-shaped and widest basally in P. braueri).

Etymology
The name of the new species (Latin reducta, reduced, an adjective) is referring to the non-setose apices of the male parameres.

Distribution
Apparently a boreal species, hitherto known from NE Finnish Lapland and Siberia, Central Russia (Fig. 3).

Ecology
The species occurs in sloping fens and swampy forests. The Finnish collecting site (sloping fen) was close to a pine and spruce dominated pristine boreal forest.

Taxon discussion
The new species was illustrated for the first time by Ostroverkhova 1979 (the original illustration is reproduced here, Fig. 12), as P. annulata, (= P. braueri). These two taxa are indeed closely related, but due to differences in the male hypopygia and DNA barcodes are considered as distinct species (see Diagnosis for details; comparative photos of P. braueri are provided in Fig. 13). There are a total of 10 slide-mounted "Phronia braueri" in TSU that were studied by Ostroverkhova, all of them collected from two close-lying localities, between dates 19. -29.7.1972. Unfortunately these slides are in poor condition making it difficult to identify them to species level; however the slide in the best condition was selected as the paratype.
There are two questionable older names of P. braueri, namely P. annulata Winnertz andP. vittata Winnertz (Winnertz 1863, Hackman et al. 1988), both are considered here as nomina dubia. These species are known from holotype females only and females of P. braueri are difficult to separate from P. forcipata Winnertz (Hackman 1970). It is also likely that the type specimens were destroyed during WWII (Kurina 2004, citing Evenhuis 1997. Furthermore, most likely the type specimens of both P. annulata and P. vittata were collected from Krefeld, Germany, that is a nemoral lowland area. We consider P. reducta sp.n. having a boreal range, being absent from Central Europe. Thus, we find it very unlikely that these nomina dubia would be conspecific with the new species. The holotype male is the only member of the BIN BOLD:ADD3565. This specimen has no very close matches in BOLD database. The closest matches are 44 Phronia specimens, whose similarities to the new species range between 96,74 -96,01. One of these specimens is assigned to P. braueri, the sister species of P. reducta sp.n. That P. braueri specimen is collected from Norway and was identified by J. Kjaerandsen (unpublished record). Coxae and legs yellowish brown, bearing dark setae. Length ratio of femur to tibia for fore and mid legs (hind legs are missing from the holotype, ratios of that leg are form the German paratype): 0.93, 0.9, 0.76. Length ratio of tibia to basitarsus for fore and mid legs: 0.96, 1.21, 1.5. Anteroapical depressed area of the fore tibia ovate, having numerous light setae over the area. Ratio of apical width of tibia:length of longest tibial spur for fore and mid legs: 0.67, 0.33, 0.23.

Phronia prolongata
Abdomen. 9th tergite and cerci as in Fig. 14a. Ventroapical projection of gonocoxites conspicuous, relatively long and narrow (Fig. 14c). Ventral lobe of gonostylus triangular, with a rather long and pointed ventrobasal outgrowth (Fig. 14d). Dorsal lobe of gonostylus relatively short, about 1.6 times longer than basally wide, bearing numerous setae (Fig. 14b, c, d). Mesial portion of gonostylus bearing 13-14 rows of combs, and a finger-like projection that is mostly bare, having an apical comb-row (Fig. 14d). Aedeagus (in lateral view) is evenly curved along its length and parameres are very long, about as long as aedeagus (Fig. 14e, f).

Diagnosis
Phronia prolongata sp.n. is a closely related species of P. exigua (Zetterstedt, see Fig.  16). The ventroapical projection of the gonocoxites in the new species is rather long and narrow (shorter and broader in P. exigua), the aedeagus (in lateral view) is evenly curved along its length (less curved in P. exigua) and the parameres are very long, about as long as the aedeagus (much shorter in P. exigua, less than 0.5 times the length of the aedeagus).

Etymology
The name (Latin prolongata, an adjective) of the new species refers to the elongated, prolonged parameres of the male hypopygium.

Distribution
The new species has a Holarctic range, it is known from Canada (British Columbia), Norway, Finland and Germany (Fig. 3). Fennoscandian sites are located in the Arctic-Alpine ecoregion and the collecting site in Germany was at high altitude alpine zone. NJ-tree of Phronia prolongata sp.n. and related taxa based on COI (mtDNA) sequences and K2P distances (data from BOLD database). 95-98 represent P. prolongata sp.n. specimens studied here; the species displays a notable intraspecific variation of the barcoding gene COI, but all specimens are considered conspecific. The Canadian specimen is a female, and its identification is solely based on the COI sequence; Nearctic male specimens should be seen in order to validate the taxonomic assignment proposed here.

Ecology
The Finnish collecting site was a swampy riparian birch forest and in Germany the species was collected from an alpine meadow.

Taxon discussion
The new species belongs to a group of species clastered with P. exigua, all sharing a beaked, setose ventral lobe of the gonostylus (ventrobasal outgrowth of the ventral lobe of gonostylus) and a row of ventral setae on the hind tibia (Gagné 1975). The new species is relatively close to P. egregia Dziedzicki, a species having very wide and apically expanded ventroapical lobe of the gonocoxite (see e.g. Gagné 1975, fig. 14 andZaitzev 2003, fig. 93.2); this lobe in the new species is rather narrow and apically very slightly expanded (Fig. 14c). The closest relative of the new species is apparently P. exigua, that has a wide ventroapical lobe of the gonocoxite, the aedeagus is not evenly curved and the parameres are short (see Fig. 15; length of paramere:length of aedeagus 0.46, this ratio is 1.0 in P. prolongata sp.n.). Coxae and legs yellow, apices of mid and hind femora sligthly infuscated, bearing dark setae. Length ratio of femur to tibia for fore, mid and hind legs: 0.99, 0.97, 0.79. Length ratio of tibia to basitarsus for fore, mid and hind legs: 1.08, 0.97, 0.8. Anteroapical depressed area of the fore tibia ovate, having ca. 20 light in a row. Ratio of apical width of tibia:length of longest tibial spur for fore, mid and hind legs: 0.35, 0.28, 0.25.

DNA barcoding
Abdomen mostly dark brown, but first, second and third tergites caudolaterally yellowish; these yellow areas are most extensive in second and third tergite. Sternum of second and third segments yellowish. Hypopygium dark brown. Ventroapical margin of gonocoxite with a wide and shallow median emargination, with a moderate median peak (Fig. 17b). Ventral lobe of gonostylus widest basally, rounded (Fig. 17a, c). Dorsal lobe of gonostylus rounded, widest subapically, having ca. 20 stout apical setae and four subapical setae that are thinner that apical setae (Fig. 17a, c). Mesial portion of gonostylus having a transversal, setose basal projection and above that two projections; the other one is simple and elongated, apically rounded, the other one is intricate, terminating into long and narrow projection (Fig. 17c). Inner lamina of the ventral lobe of gonostylus with medial a tuft of ca. eight setae, projecting perpendicularly from the lamina. Inner lamina basally, close to the edge of the stylus, with a larger group of setae. Comb-like structures are absent. Aedeagal complex rounded, length:width ratio 0.96. Aedeagal complex with a longitudinal sclerotised rod, that is basally divided into two apodemes and is apically anchor-shaped (Fig. 17d).

Diagnosis
A Phronia species with a yellowish pattern on the abdominal tergites 1-3. The ventral lobe of the gonostylus is rounded and at its widest basally. The mesial projections are finger-like and the inner lamella of the ventral lobe of the gonostylus bears a tuft of setae. The species is somewhat close to P. elegans Dziedzicki and P. signata Winnertz, that have similarly shaped ventral lobe of the gonostylus; P. elegantula can be distinguished from these due to differences in the structure of the aedeagus, the ventral lobe of gonostylus and the mesial portion of the gonostylus.

Distribution
A European species. The species was described from eastern Finland (Ok: Sotkamo and Ks: Kuusamo) and has been later recorded from southern and northern parts of the country (J. Jakovlev, unpublished). The species has been found from Russian Karelia (Polevoi 2000) and Murmansk region (Polevoi 2010). It has a wide range in Sweden (Kjaerandsen et al. 2007) and it has been once recorded from Germany, Bavaria (Plassmann 1980). The species is reported here for the first time from Norway; it may have a boreo-alpine disjunct range.

Ecology
Sampling sites are coniferous forests, mixed forests and wetlands.

Taxon discussion
Phronia elegantula is somewhat similar to P. signata and P. elegans, and has the same yellowish anterolateral corners to the scutum as well as a rotund ventral lobe of the gonostylus. However the abdomen of P. elegans is dark brown as opposed to some yellowish colouration on abdominal tergites 1-3 of P. elegantula. Phronia signata have only moderately emarginated ventroapical margins of the gonocoxites, whereas this character is much more conspicuous in P. elegantula. Phronia signata has ca. 14 setae on the ventral edge of the ventral lobe of gonostylus (see e.g. Dziedzicki 1889, fig All studied specimens belong to the BIN BOLD:ACJ2889, and their similarities range between 99.69 and 98.78 (average 99.46). The nearest specimens in BOLD database belong to P. disgrega Dziedzicki, being 90.98 % similar to P. elegantula. DNA barcode and associated data of the German paratypes and female specimens is available from the BOLD Public data portal.