Platypalpus argenticnemis Jonassen, 2021

Jonassen, Terje, Andersen, Trond, Salmela, Jukka, Suuronen, Anna & Vaesoja, Matti, 2021, Six new species of Empididae and Hybotidae (Diptera, Empidoidea) from Fennoscandia, Norwegian Journal of Entomology 68, pp. 174-186 : 178-180

Platypalpus argenticnemis Jonassen sp. n.

( Figure 3A–B )

Type material. Holotype ♂, NORWAY: Finnmark, Porsanger, Stabbursdalen , Rørkulpen, N70.15215° E24.76686°, 28m .a.s.l., 02–17 July 2010, Malaise trap no. 5, Finnmarksprosjektet ( ZMBN) . Paratypes: 1♂, same data as holotype ; 1♂, same data as holotype except 26 July–25 August 2010 . SWEDEN: 1♀, Dalarna, Jansbo , 3 km SW Snöån, N60.04880°, E15.27208° 11 June–16 July 2012 , pan trap, S. Kirppu (in coll. S. Hellqvist); 1♂, same data as previous except 16 July–16 August 2012 . 1♂ 1♀, Västerbotten, Umeå, Hamnøgern , N63.82693° E 20.17473°, 18 July 2012 , sweep net, N. Ericson (in coll. S. Hellqvist & T. Jonassen) . FINLAND: 1♂, Ks ,

Norwegian Journal of Entomology 68, 174–186 (2021)

Salla, Värriö, Kuntasjoki, N67.7494° E29.6169°, 04–29 June 2013; 1♂, same data as previous except 29 July–19 September 2013, Malaise trap, J. Salmela ( LMM: MH-EMPI-2013-0176, MH- EMPI-2013-0196) .

Additional material. NORWAY: Innlandet, Stor-Elvdal, Ottestad , N61.297111 o E11.277147 o, 21 June–20 July 2017, 1♂, 2♀♀; 20 July–06 August 2017, 1♂; 06 August–10 September 2017, 2♀♀, light trap, Hedmarksprosjektet ( ZMBN) . SWEDEN: Värmland, Eda, Skönnerud , N59.70931° E12.16705°, 20 June–10 July 2017, 1♀, pan trap, S. Emilsson (in coll. S. Hellqvist) . Ångermanland, Bjurholm, Käringberget Ekopark , N Trolltjärnberget , N63.99450° E18.77667°, 12– 26 August 2016, 1♂, Malaise trap, S. Hellqvist (in coll. S. Hellqvist) . Västerbotten, Isklinten, W Botsmark , N64.27230° E20.09096°, 20 June–04 July 2018, 1♂ 1♀, window trap, A. Garpebring (in coll. S. Hellqvist) . Åsele lappmark, Björnlandet, Rönnlandet , N63.96762° E17.96088°, 12–29 July 2014, 2♂♂, window trap, A. Garpebring (in coll. S. Hellqvist) . Åsele Lappmark, Frederika, Lödgeälven at Käringberget , N64.07916° E18.62776°, 26 July–11 August 2016, 1♂, Malaise trap, S. Hellqvist (in coll. S. Hellqvist) . FINLAND: Ks, Salla, Värriö , Kuntasjoki , N67.7494° E29.6169°, 29 June–29 July 2013, 1♂, Malaise trap, J. Salmela ( LMM: MH-EMPI-2013-0373) . Lkor, Savukoski, Urho Kekkonen kansallispuisto, Tyyroja , N68.1439° E28.5744°, 01 July–05 August 2014, 1♂, Malaise trap, J. Salmela ( LMM: MH-EMPI-2014-0933) .

DIffEREntIAL dIAgnOsIs. The species belongs in the Platypalpus ciliaris -group, but differs clearly from other related species by having numerous acrostichals and dorsocentrals together with a largely polished pleura. Further, the apical spur of mid tibia is longer than in other known European species of this group. The extensive silvery pile on front tibia is also a good characteristic; to a lesser extent, this trait can also be seen in two other Fennoscandian species, P. ciliaris (Fallén, 1816) and P. mikii (Becker, 1890) .

Description. Male. Body length 2.8 mm, wing length 3.3 mm.

Head. Black, frons and occiput polished, dusted behind ocelli. Frons broad, about 1.5 times as broad as length of second antennal segment, widening above. Face linear, dusted. Clypeus narrow, polished, as long as, or even longer than face. Ocellar bristles minute, white. Vertical bristles not discernible. Pubescence on head everywhere pale. Antennae black. Third segment short, a little longer than broad, arista about twice as long as third segment. Palpus yellow with white pubescence, moderately large, sub-triangular, broadest at tip, and with a single long hair at lower corner. Proboscis brownish black.

Thorax. Black, mesonotum completely polished, humerus, scutellum and narrow lateral margins dusted. Pleura largely polished, leaving prothoracic episternum, pteropleuron and front part of hypopleuron dusted. Hairs and bristles pale. Acrostichals small but distinct, irregularly six-serial for most of the length. Between posterior acrostichals and scutellum there is a broad band of fine but distinct, uniformly distributed hairs that continues forwards on both sides of thorax. These hairs are subequal to the row of dorsocentrals, making the dorsocentrals difficult to distinguish. This ample pilosity leaves only an irregular strip between acrostichals and dorsocentrals bare. Notopleuron with single bristle easily distinguished from surrounding pilosity. Humeral bristle lacking. Scutellum with 4 bristles, apical pair rather long, the other pair less than half as long.

Legs. Yellow including coxae, but darker in distal half of mid- and hind femur, mid tibia brownish with silvery pile apically. All tarsi clearer yellow than corresponding tibiae, last tarsal segments darker in distal half. Fore femur slightly thickened. Mid femur clearly more swollen than fore femur, with two rows of spine-like bristles ventrally, posterior row with strongest bristles. No posteroventral bristles. Fore tibia slightly spindleshaped, dorsally with silvery pile covering most of basal half. Mid tibia almost straight, with moderately large, hooked apical spur about as long as the width at apex. Hind femur and tibia long and slender.

Wing. Faintly brownish with light brown veins. Crossveins closing basal cells near contiguous. Veins R 4+5 and M only slightly curved, running parallel for most of their length. Halter pale, squama light brownish with pale hairs.

Abdomen. Black, shining, with pale pubescence. Hairs sparsely distributed all over the abdomen, hairs longer along posterior margin of sternum eight.

Terminalia ( Figure 3A–B ) moderately large. Left epandrial lamella rather narrow with extensive dorsal pubescence around the tip. Cerci small, hidden between lamellae.

Female. Very similar to male. Apical two abdominal segments and small cerci dusted.

Etymology. From Latin argenteus, silvery, and cnemis, tibia, referring to the characteristic silvery pile on fore tibia.

Distribution and habitat. The species is taken in Norway, Sweden and Finland. In northern Norway it was collected close to a moderately fast running river with banks grown with willow ( Salix ) and alder ( Alnus ) ( Ekrem et al. 2012). In Sweden it has been reported from sandy areas in Värmland, from a dry heath in Ångemanland, from a burned area in Västerbotten, and from several sites with mixed forest (S. Hellqvist in litt.). In eastern Finnish Lapland it was collected at a spring-fed headwater stream surrounded by old spruce ( Picea ) forest.

Figures

FIGURE 3.Details of Platypalpusargenticnemis Jonassen sp.n., male.A. Terminalia,dorsal view.B. Terminalia, ventral view.