Hexatoma (Eriocera) Macquart (Diptera, Limoniidae) from Xizang, China

Abstract One new species of the subgenus Eriocera Macquart,1838, Hexatoma (Eriocera) xizangensissp. nov. is described and illustrated from Xizang, China. The following four species are re-described and reported from Xizang for the first time: H. (E.) latigrisea Alexander, 1971, H. (E.) nepalensis (Westwood, 1836), H. (E.) paragnava Alexander, 1973 and H. (E.) perhirsuta Alexander, 1973. A key to the species of Eriocera from Xizang is presented.


Introduction
Eriocera Macquart, 1838 is a subgenus of the genus Hexatoma Latreille, 1809 in the family Limoniidae. It is distributed worldwide with 563 known species and subspecies, of which 69 taxa are from the Palaearctic Realm, 34 taxa from the Nearctic Realm, 143 taxa from the Neotropical Realm, 30 taxa from the Afrotropical Realm, 290 taxa from the Oriental region, and five taxa from the Australasian/Oceania realms (Oosterbroek 2021). The subgenus is thus large and morphologically diverse, and was confirmed to be non-monophyletic by Ribeiro (2008). It is characterized by the following characters: body medium to large sized; antenna with four to ten flagellomeres; wings often unpatterned through variously darkened, or with a conspicuous hyaline and yellow cross banded pattern, or abundantly spotted and dotted with brown; cell dm present; two or three branches of M reaching margin; clasper of gonostylus narrowed apically into a long curved spine; lobe of gonostylus short and stout with setae; gonocoxite moderately stubby or elongate cylindrical; interbase usually cylindrical, or triangular with a sharp spine at base, or two-layered membranous structure with spine at apex; aedeagus usually short and relatively inconspicuous, or directed ventrally (Alexander and Lloyd 1914;Edwards 1921;Alexander 1948;Alexander and Byers 1981;Savchenko 1986;Podenas et al. 2006;Ribeiro 2008;Podeniene and Gelhaus 2015).
So far, only the following four species of the subgenus Eriocera were known to occur in Xizang (Men and Yu 2015;Oosterbroek 2021): H. (E.) lanigera Alexander, 1933, H. (E.) mediofila Alexander, 1933, H. (E.) nudivena Alexander, 1933 and H. (E.) tibetana Alexander, 1933. To enrich the knowledge of the species composition of craneflies in Xizang, we conducted a scientific survey of craneflies in Xizang from 1978 to 2019. Presently, five species including one new species of the subgenus Eriocera are added to the fauna of Xizang. The following three species are reported from China for the first time: H. (E.) latigrisea Alexander, 1971, H. (E.) paragnava Alexander, 1973 and H. (E.) perhirsuta Alexander, 1973. Hexatoma (E.) nepalensis (Westwood, 1836) is for the first time reported from Xizang. Hexatoma (Eriocera) xizangensis sp. nov. is described and illustrated from Xizang. A key to the species of Eriocera from Xizang is presented.

Materials and methods
The specimens were studied and illustrated with a ZEISS Stemi 2000-c stereo microscope. Details of coloration were checked in specimens immersed in 75% ethyl alcohol. Male genitalia were prepared by macerating the apical portion of the abdomen in cold 10% NaOH for 12-15 hours. After examination, it was transferred to fresh glycerine (C 3 H 8 O 3 ) and stored in a microvial pinned below the specimen. The specimens studied, which were collected in Xizang are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing, China.
Male terminalia (Figs 1, 4-8) with 180° rotation, dull black with black setae. Posterior margin of ninth tergite with a V-shaped notch, both sides of notch with a lateral projection; posterior margin of ninth sternite with a deep V-shaped shallow; gonocoxite moderately stubby; clasper of gonostylus with long setae at base, slender, terminal     Diagnosis. Antenna has 8 segments. Wing is brown, but yellowed at basal 1/5; anal cells are much paler; a white discal area is before cord, including cell R 1 to cell CuA 1 ; m-cu is near 2/3 of cell dm. Posterior margin of tergite 9 is produced; interbase is triangular, stubby at base.
Remarks. This species is here recorded from Xizang, China for the first time. Diagnosis. Front and mouth parts are very reduced; antenna is very long and 6-segmented; vertical tubercle is very large. Wing is pale yellow; m-cu is near 1/6 of cell dm. Posterior margin of ninth tergite has a U-shaped notch; interbase is two-layered membranous structure with spine-like apex.
Redescription  Head (Figs 22-23) brown. Front and mouth parts very reduced, brownish yellow, palpus brown. Antenna 6-segmented, very long approximately three or four times as long as wing; scape and pedicel shorter, brownish yellow; flagellum very long, first flagellomere brownish yellow at base, brown at tip; remainder of flagellum brown with short blackish brown setae. Vertical tubercle more brown, very large, bulbous with setae on posterior aspect.  brownish yellow to brown with gray setae. Pronotum brownish yellow; propleuron brown; prescutum dark brown with a broad brown stripe at middle; prescutal suture brown; scutum brownish yellow to brown; scutellum yellow with a slender brownish yellow stripe at middle; mediotergite brownish yellow to brown. Thoracic pleuron mostly brown throughout, except prescutum, anepimeron, katepisternum and metakatepisternum partly brownish yellow. Legs: coxae and trochanters brownish yellow with gray setae; femora and tibiae brownish yellow with short brown setae; tarsi brown with brown setae. Wing (Figs 22, 28) pale yellow; stigma and veins brownish yellow. Venation: R 2 moderately straight; R 2+3 near half of R 2+3+4 ; cell M 1 lacking; m-cu near 1/6 of cell dm. Halter (Figs 22, 23) length approximately 1.9 mm, whitened gray. Abdomen (Fig. 22) with brownish yellow setae. First two segments more yellowed at lateral margin; segments 3-8 dark brown.
Female ( Diagnosis. Rostrum is very short; antenna has 6 segments, very long; vertical tubercle is large bulbous. Wing is brownish yellow; R 2+3 is nearly three times length of R 2+3+4 ; cell M 1 is present; m-cu is near 1/6 of cell dm. Posterior margin of ninth tergite has a deep U-shaped notch; interbase is well-developed, a two-layered membranous structure with spine apex. Head (Figs 34-35) dark brown with very long abundant brown setae. Rostrum very short, dark brown; palpi brown. Antenna 6-segmented, very long, more than three times as long as wing; scape and pedicel blackish brown with long brown setae; flagellum dark brown with short brown setae. Vertical tubercle large bulbous, dark brown with abundant very long brown setae.  yellow setae; tibiae and tarsi brown with short brown setae. Wing (Figs 34, 40) brownish yellow, stigma slightly brown; veins slightly brown, very inconspicuous against the ground. Venation: R 2 moderately straight; R 2+3 nearly three times as long as R 2+3+4 ; cell M 1 slightly longer than its petiole; m-cu near 1/6 of cell dm. Halter (Figs 34-35) length approximately 3.2 mm, halter stem grayish brown with brown setae; knob brown. Abdomen (Fig. 34) with abundant very long brownish yellow setae. First three segments brown; segments 4-8 dark brown.
Male terminalia (Figs 34,(41)(42)(43)(44)(45) brown with long brownish yellow setae. Posterior margin of ninth tergite with a deep U-shaped notch; posterior margin of ninth sternite with a deep V-shaped shallow; gonocoxite large, elongate cylindrical; clasper of gonostylus long and slender, terminal spine decurved; lobe of gonostylus short and stout, swollen with setae at middle; interbase well-developed, a two-layered membranous structure with spine-like apex; aedeagus smaller. Diagnosis. Femora are yellow. Wing is brownish yellow with the following markings: an oblique transverse hyaline marking from R extended up to CuA in base of wing; origin of Rs with a small hyaline marking; a longer oblique transverse hyaline marking from R extended to wing margin before cord; both sides of R 2 with a hyaline marking; tip of R 1 from Sc to R 3 with an oblique transverse hyaline marking. R 2 is moderately oblique, approximately as long as R 3+4 , placed before fork of R 3+4 ; cell M 1 is lacking; m-cu is near 2/3 of cell dm. Abdomen is brown to darker brown except segments 8-9 yellow. Posterior margin of ninth tergite has two small triangular processes; interbase is cylindrical, but stubby at base. Description. Male (N = 1): Body length 8.8 mm, wing length 7.2 mm. Head (Figs 46) brown with long brown setae. Rostrum very short, brownish yellow; palpi brown. Antennal scape brown with brown setae; pedicel brownish yellow; flagellum is broken. Thorax (Figs 46,47) brown with long brown setae. Legs: coxae and trochanters brown with long brown setae; femora and tibiae yellow with brown setae; basal two segments of tarsi yellow with brown setae, reminder segments brownish yellow to brown with brown setae. Wing (Figs 46, 48) brownish yellow, anal cells more yellow; anal cells with hyaline markings at base; an oblique transverse hyaline marking from R extended up to CuA in base of wing; origin of Rs with a small hyaline marking; a longer oblique transverse hyaline marking from R extended to wing margin before cord; both sides of R 2 with a hyaline marking; tip of R 1 from Sc to R 3 with an oblique transverse hyaline marking; veins slightly brown, very inconspicuous against ground. Venation: R 2 oblique, approximately as long as R 3+4 , placed before fork of R 3+4 ; cell M 1 lacking; m-cu near 2/3 of cell dm. Halter (Figs 46, 47) length approximately 1.2 mm, pale brown. Abdomen (Fig. 46) with brown setae. Segments 1-5 brown, segments 6-7 dark brown, segment 8 yellow.  (Brunetti, 1918: plate VII, fig. 12). Scale bars: 1.0 mm (46-48).

Distribution. China (Xizang).
Etymology. The species is named after Xizang Autonomous Region, where the type locality is located.
Remarks. This new species is very similar to H. (E.) decorata (Brunetti, 1918) from India (W Bengal) in having similar wing markings, but can be separated from it by the wing with a longer oblique transverse hyaline marking from R extended to wing margin before cord (Figs 46,48) and the posterior margin of the ninth tergite with two small triangular processes (Fig. 50). In H. (E.) decorata, the oblique transverse hyaline marking from R extends to the CuP before the cord (Fig. 49 i.e., Brunetti, 1918: plate VII. fig. 12; Edwards, 1924: 304;Joseph, 1977: 427, fig . 16) and the posterior margin of the ninth tergite is produced, its margin concave (Fig. 55 i.e., Joseph, 1977: 427, fig . 7). These two species are very special within the subgenus Eriocera, because of their unique position and slope of vein R 2 (Fig. 46, 48-49): it contacts vein R 3+4 (and not vein R 3 as is common in all Eriocera with a short vein R 2+3+4 ), and is sloping forwards (also a very uncommon feature in Eriocera).