﻿The genus Platypalpus Macquart (Diptera, Hybotidae, Tachydromiinae) from Inner Mongolia, China, with the description of four new species

﻿Abstract Platypalpus Macquart is reported in Inner Mongolia, China for the first time. Four new species are found: P.flavipilosussp. nov., P.longussp. nov., P.shengisp. nov. and P.shuimogouanussp. nov. This paper provides a description of the four species and a key to the genus in Inner Mongolia.


Introduction
Platypalpus Macquart, 1827 belongs to Tachydromiinae of Hybotidae.It is characterized by its raptorial mid leg and wing with an anal cell (Chvála 1975;Grootaert and Chvála 1992;Barták and Kubík 2015).The genus is cosmopolitan and found in all major zoogeographic regions, but over 75% of its 559 known species are from the Palearctic and Nearctic realms (Chvála and Wagner 1989;Grootaert 1992;Yang et al. 2007).Although most reports of the genus in the Palearctic region are from Europe, its presence in Asia is poorly documented (Barták and Shamshev 2015;Kanavalová et al. 2021).In China, 58 species have been reported, but none have been reported from Inner Mongolia, which borders Mongolia and Russia, despite the abundance of reports of the genus in these areas (Yang et al. 2007(Yang et al. , 2018;;Li et al. 2021).
Inner Mongolia is a long and narrow region located in the northern part of China, extending diagonally from northeast to southwest.The region is known for its low and uneven precipitation, strong winds, and significant seasonal variations, which nurture a diverse range of vegetation.Dongsheng District is situated in the southwestern part of Inner Mongolia and the eastern to central part of the Ordos Plateau.It has a temperate continental climate, which, coupled with its vast arid grassland, supports a unique ecosystem.Shuimogou is situated in the Helan Mountains of Inner Mongolia, a dry desert area in the middle temperate zone (Fig. 1).The region exhibits a clear vertical distribution pattern of climate, which is associated with various vegetation types, such as coniferous forests, broad-leaved forests, mixed coniferous and broad-leaved forests, scrub, grasslands, deserts, and meadows.This diverse vegetation is advantageous for the formation and maintenance of biodiversity.
In this research, the genus Platypalpus is newly reported from Inner Mongolia with four new species.A key to Platypalpus from Inner Mongolia is provided.

Material and methods
The specimens used in this study were collected by sweep nets in Inner Mongolia in 2006 and 2010.All specimens are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing.Morphological terminology follows Cumming and Wood (2009).The following abbreviations are used in the descriptions for the following bristles: acr -acrostichal bristles, av -anteroventral bristles; dc -dorsocentral bristles; h -humeral bristle; npl -notopleural bristles; vt -vertical bristles; presc -prescutellar bristles; psa -postalar bristles; sc -scutellar bristles.Diagnosis.Small to middle-sized, body length 2.0-4.0 mm; eyes narrowly separated on face; proboscis significantly shorter than head height, palpus very small, rounded; 2 pairs of vts; first flagellomere short-conical or long-conical; distinctive humerus, no distinctive humeral bristle; 2-6 rows of acrostichal bristles separated with dc; dense acrostichal on mesonotum, acr multiseriate, mixed with dc; costa vein terminating at apex of M 1+2 ; subcostal vein not reaching costal margin of wings; R 4+5 and M 1+2 parallel or distinctly convergent apically; anal vein weak or absent; 1 st and 2 nd basal cell short; anal cell significantly smaller than basal cell; no discal cell; fore femur slightly thickened; mid leg raptorial, significantly thickened, with 2 rows of short black spine-like ventral bristle; mid femur slightly curved, with 1 sparse row of black spine-like ventral bristles and 1 apical spur, apex of male abdomen rotating to right (Chvála 1975;Grootaert and Chvála 1992).Diagnosis.Thorax dark yellow, somewhat blackish dorsally.Antenna yellowish; first flagellomere oval, short, slightly wider than pedicel, 1.3 times longer than wide.Mid tibia with 1 short finger-like apical spur.Description.Male (Fig .2).Body length 2.6-2.7 mm, wing length 2.7-2.8mm.Head black, with pale gray pollen.Eyes narrowly separated on face; frons distinctly wider than face.Hairs on head yellowish, bristles black or brownish yellow.Ocellar tubercle with 2 oc and 2 short posterior hairs. 2 pairs of vt.Antenna (Fig. 6) yellowish; first flagellomere oval, short, 1.3 times longer than wide, slightly wider than pedicel, with indistinct blackish pubescence; stylus blackish, 2.9-3.0 times longer than first flagellomere, with short blackish pubescence.Proboscis yellowish, 0.6-0.7 times as long as head height.Palpus oval, longer than wide, yellowish, with yellow hairs and bristles.

Key to species (males) of Platypalpus from Inner Mongolia
Thorax dark yellow with thin pale gray pollen, blackish dorsally, humerus dark yellow, postalar callus brownish yellow; sutures of mesopleuron somewhat blackish.Hairs and bristles on thorax yellow, bristles strong; mesonotum with dense hairs, acr and dc multiseriate and not separated; 1 h, 2 npl (anterior bristle short), 1 psa, 1 presc; two pairs of sc (lateral pair short, 1/3 as long as apical pair).
Legs yellow, but tarsomere V brown apically.Hairs on legs yellowish.Fore femur slightly thickened, 1.3-1.4times wider than hind femur; mid femur distinctly thickened, 2.3-2.4 times wider than hind femur.Mid femur with 2 rows of short, black, spine-like, ventral bristles (few basal bristles brownish yellow, pv slightly longer than av), without row of outer pv.Mid tibia with 1 row of short black ventral bristles; apical spur short, finger-like (almost as long as tibia width).Wing hyaline, veins brownish; R 4+5 and M nearly parallel, r-m and m-m contiguous.Squama yellow with pale hairs.Halter yellowish.
and small, apically widely obtuse.Right epandrial lamella extremely wide and large; right surstylus (Fig. 8) short and small, pointed at tip.Left cercus (Fig. 7) strongly dilated at base, narrowed towards apex, pointed at tip; right cercus almost as long as left cercus, narrow at tip, slightly curved inwards.Female.Body length 3.0-3.5 mm, wing length 2.9-3.0 mm.Similar to male, but abdomen dark brown except sternites I-IV or I-V dark yellow.Etymology.The specific name refers to the yellow body hairs.
Remarks.The new species belongs to the P. longicornis group.It is somewhat similar to P. baotianmanensis Yang, An et Gao from Henan of China, but can be easily distinguished from the latter by the wholly blackish mesonotum and postnotum.In P. baotianmanensis, the mesonotum is yellow with a wide black middle spot, and the postnotum is brownish-yellow laterally (Grootaert and Shamshev 2006).
Legs yellow, but tarsomeres V mostly dark brown with yellow base.Hairs and bristles on legs yellowish.Fore femur slightly thickened, 1.3 times wider than hind femur; mid femur distinctly thickened, 2.1-2.2 times wider than hind femur.Mid femur with 2 rows of short spine-like blackish ventral bristles (pv distinctly longer than av), 3-4 short spine-like outer av at tip, without row of outer pv.Mid tibia with row of black ventral bristles, apical spurt short, acute (nearly as long as tibia width).
Wing hyaline, veins brownish; R 4+5 and M nearly parallel; crossveins r-m and m-m slightly or distinctly separated.Squama yellow with pale hairs.Halter yellowish.
Thorax black, with distinct pale gray pollen; mesopleuron with shiny black anterior spot.Hairs and bristles on thorax yellowish; hairs on mesonotum short and sparse; 1 weak h, 2 short npl, acr biserial, 1 long psa, 1 long presc; 2 pairs of sc (lateral pair short).
Legs yellow, but tarsomeres with narrow, blackish, apical annulation; mid femur with brown anterior spot at apex.Hairs on legs mostly yellowish except tarsi with blackish hairs; bristles mostly black.Fore femur distinctly thickened, 1.4 times wider than hind femur; mid femur strongly thickened, 2.1 times wider than hind femur.Fore femur with 1 row of short yellowish av; mid femur with 2 rows of short, black, spine-like ventral bristles and 1 row of short outer yellow av and 1 row of long outer yellow pv; hind femur with 1 row of pale yellow av (apical av rather long).Fore tibia distinctly thickened, with 3 spine-like dorsal bristles at middle, 2 rows of very long ventral hairs at apical 2/3.Mid tibia with 1 row of black ventral bristles; apical spur long and acute, with 1 short terminal hair at tip.
Etymology.The specific name refers to the specimen collector, Professor Maoling Sheng.
Remarks.The new species belongs to the P. pallidiventris-cursitans group.It is similar to P. beijingensis Yang et Yu from Beijing, but may be separated from the latter by the mid femur with a brown anterior spot at the tip, the distinctly thickened fore tibia with 3 spine-like dorsal bristles at middle and the 2 rows of long ventral hairs on the apical 2/3.In P. beijingensis, the mid femur is wholly brownish yellow, the fore tibia has no spine-like dorsal bristles and no long ventral hair (Yang and Yu 2005).Description.Male (Fig. 5).Body length 2.7 mm, wing length 3.3 mm.Head black with distinct pale gray pollen; clypeus shiny black.Eyes narrowly separated on frons and face.Hairs yellowish on head, bristles blackish.Ocellar tubercle with 2 oc and 2 very short posterior hairs. 2 pairs of vt, outer vt short and curved inward.Antenna (Fig. 18) black; first flagellomere moderately long, subtriangular, 2.1 times longer than wide, distinctly blackish pubescent; arista black very long, 2 times longer than first flagellomere, with short blackish pubescence.Proboscis nearly blackish, 0.9 times as long as head height, palpus longer than wide, lobate, obtuse apically, yellowish, with 4 brown bristles (2 apical bristles long).
Thorax black with thin pale grey pollen; mesonotum subshiny black with thin pollen; mesopleuron shiny black except postero-upper margin.Hairs on thorax yellowish, bristles yellow; mesonotum with dense hairs, acr and dc multiseriate and not separated; 1 h, 2 npl of subequal lengths, 1 psa, 1 presc; 2 pairs of sc (lateral pair short and weak, about 1/3 as long as apical pair).
Legs yellow, but mid tibia brown, all tarsi brown to dark brown except tarsomere 1 brownish yellow with brown tip.Hairs on legs yellowish, but hairs on tibia and tarsi partly blackish.Fore femur weakly thickened, 1.2 times wider than hind femur; mid femur distinctly thickened, 1.5 times wider than hind femur.Fore femur with 1 row of pv (about 1/2 as long as femur width); mid femur with 2 rows of short spine-like black bristles (pv slightly longer than av) and 1 row of 3 long blackish outer pv on apical half.Mid tibia with 1 row of short, black, ventral bristles; apical spur short, pointed, shorter than tibia width.
Wing hyaline, veins dark brown, R4+5 and M little convergent apically; 1 st basal cell slightly shorter than 2 nd basal cell, crossveins r-m and m-m very narrowly separated.Squama yellow with yellowish hairs.Halter yellowish.
Abdomen black, with pale gray pollen.Hairs and bristles on abdomen yellowish.Hypopygium : left epandrial lamella wide, with wide and blunt apex.Right epandrial lamella very wide and large; right surstylus (Fig. 20) nearly fused with right epandrial lamella, somewhat narrowed, distinctly curved inward, with distinctly apical incision bearing several short marginal hairs.Left cercus (Fig. 19) nearly finger-like, slightly broader at base; right cercus almost as long as left cercus, finger-like.
Etymology.The specific name refers to the type locality Shuimogou.
Remarks.The new species belongs to the P. pallidiventris-cursitans group.It is somewhat similar to P. henanensis Saigusa et Gao from Henan of China (Saigusa and Yang 2002), but maybe separated from the latter by the yellow antenna and mid femur with 1 row of 3 long blackish outer pv on the apical half.In P. henanensis, the antenna is black, and the mid femur has 1 row of outer pv along the whole length (Yang and Yu 2005).

Discussion
This study reports the first occurrence of Platypalpus Macquart, 1827 in Inner Mongolia.Four new species from Dongsheng and Shuimogou of Inner Mongolia are described.As the survey is restricted to only a part of the region, more reports of Platypalpus in Inner Mongolia are expected.