Trichosia (Trichosia) paraborealis, Sutou & Menzel, 2025

Sutou, Mitsuaki & Menzel, Frank, 2025, The genera Mouffetina Frey and Trichosia Winnertz (Diptera, Sciaridae) in Japan with a key for the Japanese species and an updated world checklist, Contributions to Entomology 75 (1), pp. 167-182 : 167-182

Trichosia (Trichosia) paraborealis sp. nov.

Fig. 8 A ‒ D

Type material.

Holotype. JAPAN • ♂; Honshu, Miyagi Pref., Sendai, Taihaku, Mukaiyama , mixed forest dominated by Pinus densiflora , Abies firma and Quercus serrata ; 38°14'33"N, 140°52'00"E; alt. 70 m; 30 Apr. – 23 May 2002; reared from larvae collected at 28 Apr. 2002; M. Sutou leg.; NSMT . Paratypes. JAPAN • 1 ♂; Honshu, Tochigi Pref., Nikko, near lake Yuno ; 36°48'N, 139°26'E; alt. 1500 m; 18 June 2000; K. Uesugi leg.; SDEI • 2 ♂♂, 5 ♀♀; Honshu, Tokyo, Miyake Island, Hinoyama-touge ; 34°06'N, 139°33'E; 5–7 Apr. 2010; J. Aoki leg., flight interception trap; 1 ♂, 2 ♀♀, SDEI; 1 ♂, 1 ♀, PCMS; 2 ♀♀, NSMT .

Description.

Male. Head: Eye bridge 4 facets wide. Prefrons with setae, clypeus bare. Scape brown with 2‒5 setae, pedicel brown with about 9 setae; flagellomeres brown; 4 th flagellomere about 2.5 times as long as wide, neck portion about 1 / 6 of its whole length (Fig. 8 A ), hairs yellowish brown and slightly shorter than width of flagellomere. Palpus brown, 2 - segmented (holotype) or 3 - segmented (paratypes), 1 st segment with 1‒4 setae and with indistinct sensory area bearing minute sensilla, 2 nd and 3 rd segments slender with 3‒6 setae respectively (Fig. 8 B ). Thorax: Color predominantly dark brown; mesonotum with both long and short setae; scutellum with some setae, at most 4 of them distinctly longer than the others; posterior pronotum with setae. Legs brown; tibiae and basitarsi with differentiated spine-like short setae in ground setosity; fore tibial spur about 1.3 times as long as width of tibial apex. Wing with brownish anterior veins and light brownish posterior veins; wing membrane bare; distal part of R 5 with both dorsal and ventral macrotrichia, bM and stem of M bare, r-m, M 1, M 2, CuA 1, and CuA 2 with dorsal macrotrichia; length of R 1 = 0.5‒0.7 R, c = 0.7w, r-m = 1.4‒1.6 bM but in a paratype from Tochigi r-m = 0.6 bM, stem of CuA very short, almost absent; R 1 ending slightly before level of branching point of M 1 and M 2; wing length 2.2‒2.7 mm. Halter brown, knob with setae. Abdomen: Tergites and sternites dark brown with dark brownish setae, membrane between tergites and sternites brown. Gonocoxite wider than long with broad base (Fig. 8 C ); gonostylus nearly ovoid in shape with 7‒9 spines on about upper 2 / 5 of inside (Fig. 8 D ); tegmen membranous with sclerotized border, wider than long, minute denticles located on central portion (Fig. 8 C ); aedeagus distinct and large (Fig. 8 C ). Body size: 2.3‒2.8 mm.

Female. Same as male except for the following characters: Palpus 3 - segmented, but one paratype from Miyake Island ( PCMS) asymmetrically with 3 - segmented right palpus and 2 - segmented left palpus; 1 st segment of palpus bare or with a seta. Wing vein r-m = 1.4‒1.8 bM; wing length 2.3‒2.5 mm. Body size 2.5‒3.5 mm.

Remarks.

This species is morphologically similar to T. borealis (Frey) known from Europe and Russia (Altai). The name of this new species refers to this resemblance. The morphological differences between these two species are in the structure of the male genitalia. The gonostylus of T. borealis usually has 6 spines, and the tegmen is about as long as wide ( Menzel and Mohrig 1997; Menzel and Mohrig 2000). On the other hand, T. paraborealis has the gonostylus with 7‒9 longer spines covering upper 2 / 5 of the inside (Fig. 8 D ), and the tegmen is wider than long (Fig. 8 C ). Interestingly, both these species display similar intraspecific morphological variation: they have a 2 or 3 - segmented palpus. In addition, length ratio of wing vein r-m and bM is variable in T. paraborealis : r-m is shorter than bM in a paratype from Tochigi, inversely, r-m is longer than bM in the others. The holotype of this species is an adult reared from larvae collected from rotten wood, which suggests that the larvae are xylophagous.

Figures

Figure 8. Trichosia paraborealis sp. nov., male holotype (A, C, D) and male paratype (B). A. 4 th flagellomere; B. Left palpus; C. Genitalia, ventral view; D. Right gonostylus, ventral view. Scale bars: 0.05 mm (A, B, D); 0.1 mm (C).