Gymnometriocnemus (Gymnometriocnemus) pallidus, Stur, Elisabeth & Ekrem, Torbjorn, 2015

Stur, Elisabeth & Ekrem, Torbjorn, 2015, A review of Norwegian Gymnometriocnemus (Diptera, Chironomidae) including the description of two new species and a new name for Gymnometriocnemusvolitans (Goetghebuer) sensu Brundin, ZooKeys 508, pp. 127-142 : 131-132

Taxon classification Animalia Diptera Chironomidae

Gymnometriocnemus (Gymnometriocnemus) pallidus sp. n.

Type material.

Holotype: Male adult (NTNU-VM slide 143840), Norway, Hordaland, Kvam, Berge, oak canopy fogging, tree #3, 60.30921°N; 6.16453°E, 23.vi.2011, leg. Karl H. Thunes [BOLD ID: CH-eik131]. 5 Paratypes: 2 male adults as holotype except tree #1 60.314°N; 6.167°E, 21.vi.2011; 1 female adult as holotype except tree #18, 59.201°N; 9.920°E, 5.vii.2012; 2 male adults, Norway, Telemark, Porsgrunn, Brevik, Frierflauene, 59.0579°N; 9.66485°E, Malaise trap, 30. vi– 27.vii.2010, leg. Geir Søli.

Etymology.

The species is named “pallidus”, Latin adjective meaning pale, referring to the conspicuous pale body colour compared to other Holarctic Gymnometriocnemus .

Diagnosis.

Gymnometriocnemus (Gymnometriocnemus) pallidus can be separated from other Gymnometriocnemus species by the following combination of characters in the adults: body pale yellow-green; male with short inconspicuous virga, gonostylus with convex outer margin and weakly developed crista dorsalis. Female with setae on most of wing surface, including numerous in cell m; antenna with apical flagellomere pointed and longer than flagellomere 4; genitalia with long rami, about the same length as notum.

Description.

Male adult (n = 5 unless otherwise stated). Wing length 1.21-1.30, 1.28 mm. Colouration pale yellow-green body, legs and antennae; slightly darker bands on scutum; postnotum, dorsal side of head, ventral part of preepisternum pale brown; eyes dark brown.

Head. Antennal ratio in Table 1. Temporal setae 9-10; palp lengths (in µm): 25/30/90-100/80-90 (4)/110-115 (4).

Thorax. Antepronotum with 2-6, 3 setae. Dorsocentrals 10-17, 13; acrostichals 7-12, 10, minute and difficult to discern; prealars 3-4; scutellars 6-7.

Wing (Fig. 5B). Costa moderately extended, not reaching half way to apex of M1+2; R2+3 approaching costa at 1/3 distance between R1 and R4+5. Macrotrichia present on membrane in apical half of wing, 0-2 setae in cell m. Veins Sc, R2+3, M and pseudovein without setae.

Legs. Fore tibia with one spur, 35 µm long; mid tibia with two spurs ca. 20-25 µm long; hind tibia with well-developed comb and 2 spurs, ca. 20 and 35 µm long. Fore leg ratios in Table 1.

Hypopygium (Fig. 4B). Ninth tergite with 10-15, 13 setae, median setae stronger and situated on an obvious anal point. Virga 15-20 µm long consisting of two spines. Inferior volsella well-developed lobe; gonostylus with slightly convex outer margin.

Female adult (n = 1). Wing length 1.23 mm. Colouration as male.

Head. Antenna (Fig. 3E) with five flagellomeres, lengths (in µm): 75/60/70/60/70. Temporal setae 9; palp lengths (in µm): 25/30/95/-/-.

Thorax. Antepronotum with 6 setae. Dorsocentrals 18; acrostichals 11; prealars 3; scutellars 6.

Wing (Fig. 3D). Costa well extended, reaching slightly past half way to apex of M1+2; R2+3 approaching costa at 1/3 distance between R1 and R4+5. Macrotrichia present on membrane in whole wing. Veins M, Sc and R2+3 without setae.

Legs. Fore tibia with one spur, 20 µm long; mid tibia lost; hind tibia with well-developed comb and 2 spines, ca. 35-40 µm long. Tarsus of fore leg lost (LR1 not measurable).

Genitalia (Fig. 3F). Gonocoxite IX with 7 setae. Ninth tergite undivided, semi-circular with 12 setae; cercus 50 µm long; seminal capsules about 70 µm long and 45 µm wide, seminal tubules about 325 µm long. Notum as long as rami, 87 µm. Inner lobe of gonapophysis VIII broadly rounded with numerous long medially directed microtrichiae.

Immature stages unknown

Remarks.

The species is morphologically similar to Gymnometriocnemus (Gymnometriocnemus) subnudus and Gymnometriocnemus (Gymnometriocnemus) johanasecundus , but paler (see whole specimen figures in BOLD dataset DS-GYMNO). Males and females are almost completely yellow-green with pale brown posterior side of head and postnotum; pale brown scutal bands and ventral side of preepisternum. Gymnometriocnemus (Gymnometriocnemus) pallidus is also similar to these species in having a short, triangular anal point and a small virga, but the hypopygium of Gymnometriocnemus (Gymnometriocnemus) pallidus has a more prominent inferior volsella than Gymnometriocnemus (Gymnometriocnemus) johanasecundus and considerably stronger anal tergite setae than Gymnometriocnemus (Gymnometriocnemus) subnudus (Figs 4B, C). Comparison with DNA barcode data in BOLD indicates that the species also has records from Germany and France.