Homotropus mugerwai, Johansson, Niklas, 2020

Johansson, Niklas, 2020, Additions to the Swedish fauna of Diplazontinae (Hymenoptera: Ichneumonidae) with the descriptions of five new species, European Journal of Taxonomy 724, pp. 70-92 : 77-80

Homotropus mugerwai sp. nov.

urn:lsid:zoobank.org:act:314328E3-4E48-45CD-A609-E0BBA965B5ED

Figs 5B , 6

Diagnosis

Homotropus mugerwai sp. nov. ( Fig. 6 ) is similar to and easily confused with Homotropus pallipes (Gravenhorst, 1829) , but has the mesoscutum polished with quite distinct punctures ( Fig. 5B ), while it is shagreened with indistinct punctures in H. pallipes ( Fig. 5A ). The area covered by microsculpture on the mesopleuron is ending lower than in Homotropus pallipes . The two known females lack pale shoulder marks anteriorly on the lateral part of mesoscutum, a feature which is present in all but one female specimen of H. pallipes studied by the author (n = 89), even if the mark is smaller and less distinct in northern specimens. The pterostigma is brownish with the basal part paler, but entirely yellowish in H. pallipes . The mid-coxae in the two known females are almost entirely yellow, while they are orange at least basally in H. pallipes . The species is also similar to Homotropus signatus (Gravenhorst, 1829) , but has more numerous flagellomeres, 20 in Homotropus mugerwai sp. nov. and 19 in H. signatus . The metasoma is also less strongly compressed apically than in H. signatus . The scutellum is entirely yellow in Homotropus mugerwai sp. nov. and the hind trochanter has a dark spot while the scutellum in H. signatus is black or only with a small yellow spot apically and the hind trochanter lacks any dark markings.

Type material

Holotype SWEDEN • ♀; Västerbotten, Åselet, Hästholmen ; 65.233° N, 20.414° E; 25 May–19 Aug. 2019; R. Mugerwa Pettersson and S. Hellqvist leg.; Malaise trap in riverside, herb rich, mixed forest; NHRS- HEVA000011634 .

Paratype SWEDEN • 1 ♀; Västerbotten, Fällfors, Marranäset ; 65.109° N, 20.790° E; 25 May–19 Aug. 2019; R. Mugerwa Pettersson and S. Hellqvist leg.; Malaise trap in riverside, decidous forest. NHRS- HEVA000011633 .

Etymology

The specific epithet mugerwai (masculine name in genitive case) is derived from the name of one of the the collectors, Roger Mugerwa Pettersson (Robertsfors, Sweden).

Description

Female

Fore wing length 4 mm. Body length 4.5 mm. Head transverse in anterior view. Inner orbits almost parallel. Face entirely coriaceous and matt. Clypeus with apical margin bilobed and thin, weakly excised centrally. Antennae with 20 flagellomeres. First flagellomere about 5.5–6.0 times as long as wide. Apical flagellomeres with multiporous plate sensilla also present ventrally. Head behind eyes slightly narrowed. Temple in lateral view about 0.5 times as wide as compound eye. Mesopleuron in lower half with weak rugulose microsculpture, in upper half polished. Metapleuron strongly coriaceous. Mesoscutum shining with small punctures, centrally with very weak microsculpture ( Fig. 5B ). Propodeum evenly coriaceous with only pleural carinae present. Fore wing with areolet closed and vein 3rs-m weakly pigmented. Coxae coriaceous, matt. Pterostigma light brownish, basally pale ( Fig. 6 ). Metasoma laterally weakly compressed from the 4 th tergite ( Fig. 6 ). First tergite about 1.5 times as long as wide, coriaceous with weak longitudinal striae. Second tergite coriaceous with weak striation basally, striae reaching about 0.5 times length of tergite. Third tergite coriaceous, apically becoming more or less reticulate-coriaceous. Fourth tergite onwards reticulate-coriaceus. Spiracle of second and third tergite above lateral fold. Ovipositor sheath apically rounded.

COLOURATION. Body and head black. Mandibles, lower part of clypeus, palpi, subtegular ridge, hind corner of pronotum, tegulae and weak central spot on face whitish. Scutellum entirely yellow. Legs orange. Fore and mid coxae, trochanter and trochantelli yellow, fore and mid coxae at most with very small dark spot basally. Hind coxae orange. Hind trochantellus with small black spot. Tibae whitish, with apical 0.3 and base narrowly black. Hind tibia with subbasal black spot dorsally. Metasoma black. Apical third of tergite 2 and the entire tergites 3 and 4 orange.

Male

Unknown.

Remarks

In the key to the species of Homotropus provided by Klopfstein (2014b), Homotropus mugerwai sp. nov. will run to couplet 30 as H. pallipes , from which it is distinguished by the characters given in the diagnosis.

Ecology

The two known females were collected by Malaise traps situated in herb rich riverside boreal forests dominated by Betula spp. ( Fig. 12 A–B). Both areas are periodically flooded. The trap at Hästholmen also collected several other rarely recorded diplazonines such as Syrphoctonus idari , Homotropus melanogaster , Diplazon neoalpinus , Syrphophilus asperatus and the here described Homotropus hellqvisti sp. nov.

Figures

Fig. 5. A–B. Mesoscutum of female, anterodorsal view. A. Homotropus pallipes (Gravenhorst, 1829). B. Homotropus mugerwai sp. nov., paratype (NHRS-HEVA000011633). C–D. Head, anterior view of female. C. Homotropus hellqvisti sp. nov., paratype (NHRS-HEVA000011637). D. Homotropus collinus (Stelfox, 1941). E–F. Posterior segments of metasoma of female. lateral view. E. Homotropus melanogaster (Holmgren, 1872). F. Homotropus collinus.

Fig. 6. Homotropus mugerwai sp. nov., paratype, ♀ (NHRS-HEVA000011633). Habitus, lateral view.

Fig. 12. A. Malaise trap at Hästholmen by the forest river Byskeälven. Type locality for Homotropus hellqvisti sp. nov. and Homotropus mugerwai sp. nov. Photo: Roger Mugerwa Pettersson. B. The Natura 2000 area Byskeälven from Marranäsvältan. Photo: Sören Uppsäll, Länsstyrelsen.