Chionea mirabilis, Vanin, 2008

Vanin, Stefano, 2008, Chionea (Chionea) mirabilis n. sp., a new species of snow fly (Insecta, Diptera, Limoniidae) from Korea, Zoosystema 30 (2), pp. 413-418 : 414-417

Chionea mirabilis n. sp.

TYPE MATERIAL. — Holotype: Korea. Muryong-san , Togyusan, 500-600 m, sur la neige (25 cm), 27.I.1998, Tripotin coll., ♂ ( MNHN).

Paratype: ibidem, ♂ ( MNHN).

ETYMOLOGY. — The species epithet derives from the Latin mirabilis , mirabile meaning wonderful, marvellous.

DIAGNOSIS. — A yellowish-brown species, with body and legs bearing several long, yellow setae. Frons prominent. Antennae with five flagellomeres beyond fusion segment. Femora enlarged, tibiae strongly apically inflated. Dististyles dark with small basal teeth, and with apices lighter, bearing conspicuous tuft of setae.

The new species differs from its congeners and consubgeners mainly by the following combination of characters: shape of tibiae apically enlarged and, also more evident, the presence of wings longer than in the other described species. Moreover C. mirabilis n. sp. differs from C. araneoides Dalman, 1816 and C. pusilla Savchenko, 1983 by the absence of valves in the inner genital apparatus and from C. crassipes , C. nipponica Alexander, 1932 and C. kanenoi Sasakawa, 1986 by the number of the antennal segments (respectively 8 in C. mirabilis , 6 or 7 in C. crassipes , 9 or 10 in C. nipponica and 11 in C. kanenoi ), by the shape of the basistyles and dististyles with small basal teeth as well as by the setae distribution.

DESCRIPTION

Description based on 2 males, collected in Korea on snow, double mounted (minuten in entomological card label).

Head, including antennae, eyes and palpi, brown, strongly darker than thorax. Frons prominent and glabrous, vertex with several long, yellow setae backwards oriented.Antennae consisting of scape,pedicel, fusion segment and 5 flagellomeres; last segment very small, with 3 or 4 apical setae. Compound eye formed by more than 150 ommatidia.

Thoracic dorsum (mesonotum) yellowish-brown (reddish), with several long yellow setae on pronotum. Yellow shining setae on mesonotum directed backwards, lacking on median part.

Wing longer than usually in the genus, and also longer than haltere (0.650 mm vs 0.500, holotype; 0.500 vs 0.375, paratype), white, long, fine, grad- ing into dark, grey-dark on apical part. Halteres pale white, distinctly contrasting with colour of thoracic dorsum (mesonotum); haltere-basal sclerite darker.

Legs yellowish to yellowish-brown, trochanters darker, with several long yellow setae. Femora with glabrous area at posterior side, particularly evident on second and third legs. All tibiae enlarged and rounded bulge at tarsal articulation, a peculiar characteristic exclusive to this species ( Fig. 1).

The lengths of the legs of holotype and paratype are reported in Table 1. All femora have the same maximal width (0.50 mm in the holotype).

Abdomen darker than thorax. Terga 1-8 brown, reddish brown, darker than thorax, each with posterior margin bearing several long, yellow setae. Ninth tergum with long setae on median part, posterodorsal margin linear with glabrous median area.

Basistyles (= gonocoxite) short, with long setae both on dorsal and ventral sides ( Figs 2 ; 3 ). Dististyles (= gonostylus), shining dark with apical part lighter, mostly glabrous on basal and median parts, with small basal teeth. Apices of dististyles with conspicuous tuft of setae ( Fig. 3 ). Parameres triangular, apically rounded and internally folded, ventral side with fine short setae. Plaits short, apically rounded with fine, short dorsal setae.Aedeagus tapered apically ( Fig. 4).

Body length: in dry preparation, the abdomen is contracted and it is not possible to define the real body length. Although very strong differences are present in the body length among Chionea species and among individuals belonging to the same species, I propose herein to use the length of the head and the femora as morphometric parameters for studies on the genus Chionea .

REMARKS

The male genitalia of C. mirabilis n. sp. are characterized by a double lobe on the base of the distal part of the gonapophyses, a short, thick aedeagus, and short triangular parameres. These features are typical of the species belonging to the subgenus Chionea . Moreover, males of C. mirabilis n. sp., as well as that of C. crassipes (widespread from North Europe to Korea and, C. nipponica and C. kanenoi (described from Japan), lack valves, making their inner genital apparatus simpler than the other Palaearctic Chionea species (e.g., C. araneoides and C. pusilla ). The shape of the gonopophyses, “claspetten” and aedeagus of C. mirabilis n. sp. are comparable with the just reported Chionea species , C. crassipes , C. nipponica and C. kanenoi (see Alexander 1932; Krzeminski 1982; Sasakawa 1986), but these features are not shared by the North American species (see Byers 1983). The male genital structure and the number of flagellomeres suggest that C. mirabilis n. sp., C. crassipes , C. nipponica and C. kanenoi are phylogenetically related and closer to the other palaearctic Chionea species assigned to Chionea s.s., than to the North American species.

The specimens of C. mirabilis n. sp. were collected on the snow during the winter at 500-600 m above sea level. These ecological data agree with the previously reported data for other Chionea species recorded at comparable latitudes ( Byers 1983; Vanin & Masutti 2008).

Figures

FIG. 2. — Chionea mirabilis n. sp., holotype ♂, detail of the last abdominal segments of male in ventral view (vacuum mode:variable pressure; VP Target: 4.50 e-001 Torr). Scale bar: 200 μm.

FIG. 3. — Chionea mirabilis n. sp., holotype ♂, basistyle in dorsal view (vacuum mode: variable pressure; VP Target: 4.50 e-001 Torr). Scale bar: 100 μm.