Litoleptis Chillcott

Imada, Yume & Kato, Makoto, 2016, Bryophyte-feeding of Litoleptis (Diptera: Rhagionidae) with descriptions of new species from Japan, Zootaxa 4097 (1), pp. 41-58 : 43-44

Litoleptis Chillcott

Type species: Litoleptis alaskensis Chillcott 1963: 1187 , by original designation. L. chilensis Hennig 1972: 6 .

L. orientalis as Hilarimorpha ; Frey 1954: 25. L. fossilis Arillo et al. 2009 .

Description. Head ( Fig. 2 b, c) dark brown, glossy. Vertex, occiput, postgena with sparse setae, gena bare. Eyes inconspicuously setulose; slightly dichoptic or holoptic in male, dichoptic in female; in male, upper part orange, lower part black. Mandibles absent. Antenna black or pale grey. Pedicel clearly larger than scape. Scape minute, pedicel as broad as long and weakly bristled around distal edge. Clypeus slightly bulbous. Palpus one-segmented, with black setae. Labellum developed, without pseudotracheae.

Thorax ( Fig. 2 a) brownish black with pruinosity and with three dark brown vittae. Postpronotal lobe, proepimeron, bare. Scutellum with sparse setae on posterior margin. Mesonotum without vittae. Proscutellum absent. Subscutellum inconspicuous. Proepimeron developed. Postscutellum bare. Anatergite and katatergite indistinguishable.

Wing ( Fig. 4 ) infuscate, without any dark markings, despite having intraspecific variation in color darkness. Pterostigma inconspicuous. Lower calypter reduced. Upper calypter triangular in form, underdeveloped; with broad curvature. Costa ending before wing tip. Humeral crossvein weakly developed. Crossvein sc-r present, positioned proximal of humeral crossvein. R1 dorsal and ventral surface bare. R2+3 sinuous, apical third of R2+3 ultimately bends anteriorly slightly, toward leading edge of wing margin; longer than R5, but less than twice as long. Fork of R4+5 distal of distal end of fork of M1+2. R4 at base mostly straight, ending at wing tip entire length. R5 ending at wing tip. M3 absent. Medial crossvein absent. CuA2 generally join with A1. CuA2+A1 reaching or sometimes not reaching wing margin. Anal cell closed usually before and sometimes at wing margin. Alula reduced with narrow curvature; rounded evenly.

Legs dark brown to black; coxae and femora more or less pollinose with weak setae. Empodium pulvilliform. Tibial spur formula 0:0:0. Macrotracheae absent. Postmetacoxal bridge absent. Hind coxae bare behind.

Abdomen dark brown to black with pruinosity.

Male Cercus displaced away from epandrium, widely displaced from one another, separation distance about 3/ 4 width of cercus; held vertically over abdomen; flat dorso-ventrally. Tergite 10 absent. Hypandrium fused entirely to gonocoxites. Gonocoxal ridge absent. Gonocoxal apodeme absent. Gonostylus with developed extension apically from apex of main component. Aedeagus slender and conical-shaped; apical surface covered with tiny pustules; connected with paramere at base. Lateral ejaculatory process either present or absent. Aedeagal tines absent. Endoaedeagal process absent. Sperm sac bulbous, generally without distinct lobes, envelope aedeagus ventrally.

Female (for L. japonica , kiiensis , niyodoensis , asterellaphile ; Fig. 2 d) Tergite 7 wider than long. Tergite 9 bare, inconspicuous and largely retracted within tergite 8; having ventrolateral projections, extending posteriorly, surrounding and fusing sternite 9 laterally. Intersegmental membrane clearly separating tergites 7 and 8. Spermathecae three, membranous. Spermathecal duct short, less than length of sternite 9. Spermathecal duct accessory glands with short, sclerotized columnar duct. Circular ridge of ejection apparatus absent. Ring at base of spermathecal ducts lightly or not sclerotized. Spermathecal duct ejection apparatus absent. Common spermathecal duct absent or inconspicuous. Surrounding area of genital chamber membranous, contained sclerotization of sternite 9 laterally.

Diagnosis. Litoleptis can immediately be distinguished from the other genera of Rhagionidae . Major autapomorphies are as follows: medial crossvein (and discal cell) absent; all tibiae without spurs; gonocoxal apodeme absent. Litoleptis specifically mostly resembles Spania in general appearance and stylus-shaped antenna, although they can easily be distinguished by the following character states besides the above-mentioned traits; male gonostylus with an extension from apex of main component expanding into an irregular form (as opposed to constantly slender or club-like form in Spania ); gonocoxal apodeme absent. Also, the Japanese Litoleptis shows inconsistency in having the following traits unlike other congeners (e.g. L. alaskensis ): male eyes dichoptic; lateral ejaculatory process present (except L. japonica ); ejaculatory apodeme present. The following traits are uniquely found in the Japanese Litoleptis : apex of aedeagus covered with numerous tiny pustules; spermathecal duct accessory glands connected by short, sclerotized columnar duct arising from spermathecal duct.

Figures

FIGURE 2. Morphological features of Litoleptis applied in this study. (a) General appearance of adult of L. japonica sp. n. in lateral view, (b) head of adult male of L. japonica sp. n. in anterior view, (c) head of adult male of L. kiiensis sp. n. in anterior view, (d) female genitalia in dorsal view. (e) ventrolateral process of female of L. kiiensis sp. n. in lateral view. Abbreviations: anatg, anatergite; anepm, anepimeron; anepst, anepisternum; fc, face; gn, gena; hlt, halter; kepst, katepisternum; ktg, katatergite; lbl, labellum; mr, meron; oc, ocellar; pgn, postgena; plp, palpus; pprn lb, postpronotal lobe; prepm, proepimeron; prepst, proepisternum; sctl, scutellum; vl proc, ventrolateral process.

FIGURE 4. Wings of Japanese Litoleptis species. (a) L. japonica sp. n. [Rh 0017], (b) L. kiiensis sp. n. [Rh 0221], (c) L. niyodoensis sp. n. [Rh 0186], (d) L. himukaensis sp. n. [Rh 0197], (e) L. izuensis sp. n. [holotype], (f) L. asterellaphile sp. n [Rh 0211]. Abbreviation: H, humeral crossvein.