Morphological phylogenetic analyses and taxonomic revi sion of the Panorpa davidi group (Mecoptera: Panorpidae)

The Chinese Panorpa species without anal horn are normally assigned to the Panorpa davidi group. Here, we taxonomically revise the P. davidi group, which currently includes 17 known species and four new species: P. gaokaii sp. nov., P. huayuani sp. nov., P. uncinata sp. nov. and P. yaoluopingensis sp. nov. Panorpa shanyangensis Chou & Wang, 1981 and P. sexspinosa zhongnanensis Chou & Ran, 1981 are treated as junior synonyms of P. sexspinosa Cheng, 1949. We describe for the first time the male of P. stigmosa Zhou, 2006, and the females of P. curva Carpenter, 1938, P. davidi Navás, 1908, P. difficilis Carpenter, 1938, P. fructa Cheng, 1949, and P. jinchuana Hua, Sun & Li, 2001. A key to species of the group is provided. Phylogenetic analyses of maximum parsimony and maximum likelihood based on 79 morphological characters show that the newly defined P. davidi group is a well-supported monophyletic group and is sister to the genus Cerapanorpa Gao, Ma & Hua, 2016.


Morphological phylogenetic analyses and taxonomic revi sion of the Panorpa davidi group (Mecoptera: Panorpidae) Introduction
Panorpidae, the largest family of Mecoptera, consist of approximately 500 extant species in eight genera Wang et al. 2019;Hu and Hua 2020). The genus Panorpa Linnaeus, 1758 is the largest taxon in Panorpidae, comprising approximately 270 extant species widely distributed in Asia, Europe, and North America (Esben-Petersen 1921;Wang et al. 2019). Panorpa has been confirmed to be paraphyletic based on molecular data (Whiting 2002;Hu et al. 2015;Miao et al. 2019) and morphological characters (Willmann 1989;Ma et al. 2012; Wang and Hua 2020), and needs continued taxonomic revision.
The species of Panorpa are divided into various species groups for local faunas based on different morphological criteria (Esben-Petersen 1921;Carpenter 1931Carpenter , 1938Issiki 1933;Cheng 1957;Willmann 1977;Byers 1993). The European species are divided into three groups (Willmann 1977). The North American species are categorized into three (Carpenter 1931) or four groups (Byers 1993). The Japanese-East Asiatic species are cat-egorized into four (Esben-Petersen 1921) or nine groups (Issiki 1933). Based on the number of anal horns on the posterior margin of tergum VI in males, the Chinese fauna is assigned to three species groups: the P. davidi group (without anal horn), the P. centralis group (with a single anal horn), and the P. diceras group (with two anal horns) (Carpenter 1938;Cheng 1957). The P. diceras and P. centralis groups have been raised to generic status as Dicerapanorpa Zhong & Hua, 2013 and Cerapanorpa Gao, Ma & Hua, 2016, respectively. Another genus, Sinopanorpa Cai & Hua, 2008 is established for P. tincta Navás, 1931 and related species, former members of the P. davidi group (Cai et al. 2008).
The P. davidi group is considerably diverse in morphology (Ma et al. 2009(Ma et al. , 2011(Ma et al. , 2012Jiang et al. 2019;Miao et al 2019). Their eggs differ mainly in the ridges of the extrachorion, protuberances within the cells and arranged pattern of the pole area (Ma et al. 2009). Male salivary glands are varied markedly in the number and shape of secretory tubes (Ma et al. 2011). The female genitalia vary distinctly in the developed degree of the main plate and axis; the relative length of the main plate and posterior arm; and the number, shape and position of the basal plates among species (Ma et al. 2012). The first-instar larvae exhibit prominent differences in chaetotaxy on the head and body Hua 2013, 2016;Jiang et al. 2019). Morphological and molecular phylogenetic analyses suggest that the P. davidi group is paraphyletic (Ma et al. 2012;Hu et al. 2015;Miao et al. 2019). Therefore, a taxonomic revision is urgently needed.
In this study, we present a taxonomic revision of the P. davidi group, propose two new synonyms and describe for the first time the male of one species and females of five species. Four species are described as new to science.
A key to species of the P. davidi group is provided. Phylogenetic analyses of the P. davidi group were conducted using maximum parsimony and maximum likelihood based on morphological characters.

Material and methods Taxonomy
More than 1000 adult specimens in the P. davidi group were examined. The specimens are mainly stored in the Entomological Museum, Northwest A&F University, China (NWAU), except P. jinchuana Hua, Sun & Li, 2001 in the Tianjin Natural History Museum, China (TJNH). Specimens were dissected under a Nikon SMZ 1500 Stereoscopic Zoom microscope. Wings were measured with a vernier caliper. Male aedeagal complex and female medigynia were macerated in cold 5% NaOH for 5 min. Pictures of adult habitus were taken with a Canon EOS 70D digital camera, and pictures of dissections were taken using an advanced Stereo Microscope System (Discovery V20, Zeiss; an auto-montage imaging system Axio ICc5). Photographs were assembled and annotated with Adobe Photoshop CS6. Detailed illustrations are provided for new species, known species whose male or female are described for the first time, and P. sexspinosa with new synonyms.

Phylogenetic analyses
Phylogenetic trees were reconstructed using maximum parsimony (MP) and maximum likelihood (ML). A total of 38 species were selected for character coding and phylogenetic analyses, including 21 species of the P. davidi group, five species of other Chinese Panorpa without anal horn, P. communis Linnaeus, 1758 (the type species of Panorpa) and its closely related species P. sibirica Esben-Petersen, 1915, ten species of other genera of Panorpidae. Panorpodes kuandianensis Zhong, Zhang & Hua, 2011 in Panorpodidae was selected as outgroup. A data matrix containing 79 characters coded for 39 taxa was created using Mesquite v. 3.61 (Tables S1-S2) (Maddison and Maddison 2019).
All characters were equally weighted. Traditional search with 100 replications was conducted with TNT 1.1 (Goloboff et al. 2008). Bremer support values (BR) (Bremer 1994) and bootstrap support (MPBS) values (Felsenstein 1985) were calculated with TNT. The unambiguous characters were mapped on the most parsimonious tree and the strict consensus tree using WinClada version 1.00.08 (Nixon 2002). The ML analysis was performed with IQ-TREE (Nguyen et al. 2015) under Ultrafast bootstrap. Bootstrap support (MLBS) values were evaluated with 5000 replicates. -Gonocoxites with cluster of stout dark brown setae and 3-5 long setae along oblique inner apex ventrally; without acute protuberance (Fig. 9B) Chou, 1981 -Wing membrane hyaline, without markings; parameres slender, intensely curved, reaching middle of aedeagus (Fig. 3B) Carpenter, 1938 15. Forewing with basal band reduced into middle spot, extending from M to anal margin (Fig. 23A) Cheng, 1949 -Hypovalves with apical third widest, then tapered towards apex (Fig. 17E)..... P. jinchuana Hua, Sun & Li, 2001 19. Forewings without basal spot (Figs 18B, 19A Diagnosis. This species can be recognized by the following features: (1) occiput black, with two pale submedian stripes and two eye-shaped speckles on lateral regions; (2) wing membrane hyaline, pterostigma prominent yellow, almost without markings ( Fig. 2C-D); (3) 1A ending before origin of Rs (Fig. 2C); (4) meso-and metanotum pale with yellowish brown laterally, and pale color extending to T3 in V-shape (Fig. 2C); in males, (5) inner apex of gonocoxite bearing 3-6 long black bristles; (6) parameres crossed, twisted in S-shape, reaching apex of gonocoxites; in females, (7) medigynium with main plate twice as long as wide; a pair of small lateral basal plates near middle; axis extending beyond main plate one-third its length anteriorly. Remarks. This species resembles P. chengi in appearance, but can be differentiated from the latter by vein 1A ending before (cf. at) the origin of Rs.  Diagnosis. This species can be readily recognized by the following characters: (1) wings devoid of markings, pterostigma faint ( gonostylus with broad row of stout setae on inner margin; (5) gonocoxites bearing 4-6 short setae along beveled inner apex ventrally, with small protuberance below setae; (6) parameres slender, intensely curved, reaching half length of aedeagus; in females, (7) medigynium with main plate oblong; axis extending beyond main plate more than half its length anteriorly; lateral basal plates absent. Diagnosis. This species can be readily recognized by the following characters: (1) forewing apical band broad, with small hyaline spot posteriorly; pterostigmal band with basal branch broad and apical branch mostly absent; basal band complete, broad; marginal and basal spots absent ( Fig. 4A-B); (2) meso-and metanotum black, with prominent pale yellow mesal stripe ( Fig. 4A-B); in males, (3) gonocoxites with elongated process, bearing short stout setae on inner margin (Fig. 4E); (4) parameres   pair of large wing-like lateral basal plates near middle portion; paired posterior arms forming broad U-shaped emargination; axis slightly extruded posteriorly, extending beyond main plate for two-fifths of its length anteriorly.
Remarks. This species resembles P. davidi in appearance, but can be readily identified by complete basal band (cf. split into two spots) in forewing and elongated process on gonocoxites with the base 1.5 times (cf. twice) as wide as the apex.

Female. Unknown.
Measurements. Male: FL = 11 mm, FW = 2 mm; HL = 10 mm, HW = 2 mm. Diagnosis. This species can be readily recognized by the following characters: (1) forewing markings well-developed, apical band broad and scattered posteriorly; pterostigmal band with basal branch complete and apical branch separated or absent; basal band split into two spots; basal spot greatly reduced ( Subgenital plate elliptical, with V-shaped distal emargination, bearing long setae on distal part. Medigynium with oblong main plate, three times as long as wide, and lateral margin emarginate at basal one-third; paired posterior arms quarter as long as main plate, forming broad U-shaped emargination; axis slightly extruded posteriorly, extending beyond main plate for half of its length anteriorly.

Distribution. China: Sichuan.
Remarks. Only a single male (holotype) of P. davidi from Baoxing, Sichuan was known previously. A female specimen was erroneously treated as P. davidi by Navás (1908), but was later designated as the holotype of P. guttata Navás, 1908(Esben-Petersen 1915. A female of P. davidi captured recently from the type locality can be differentiated from that of P. guttata by the well-developed (cf. greatly reduced) wing markings and by meso-and metanotum black (cf. yellowish brown), with a narrower (cf. broad) pale yellow mesal stripe.

Panorpa difficilis Carpenter, 1938
Figs 6-7 Diagnosis. This species can be readily recognized by the following characters: (1) wings with well-developed variable markings (

Panorpa fructa Cheng, 1949
Figs 10-11 Panorpa fructa Cheng, 1949 Diagnosis. This species can be readily recognized by the following characters: (1)     Remarks. Panorpa fructa was originally described based on a single male specimen. Over two dozen female specimens from Kangding, the type locality, are determined here as members of this species. The specimens were collected at high-altitude from 3300 to 4000 m in alpine shrub meadow (Fig. 10A). The darker body may help absorb solar heating to adapt the cold environment. The adults hold wings roof-like at repose (Fig. 10B), which may be adapted to the strong wind environment in the alpine region. twice; in females, (6) main plate of medigynium broad; pair of large lateral basal plates extending from base to two-thirds of length of main plate; axis extended beyond main plate one-third of its length anteriorly.
Distribution. China: Shaanxi.  14D); (6) gonocoxites bearing cluster of black setae on inner apex (Fig. 14F-G); (7) parameres crossed, twisted in S-shape, reaching apex of gonocoxites (Fig. 14H); in females, (8) medigynium with main plate broad, long, twice as long as wide; a pair of large lateral basal plates reaching three-fourths of length of main plate; posterior arms half length of main plate; axis extended beyond main plate for half of its length anteriorly, extruded posteriorly ( Fig. 14K-L).
Etymology. The specific epithet is dedicated to Kai Gao, the collector of the type specimens, for his support to this research. 14A, D): T2 and T3 unevenly pale with lateral and posterior margins dark brown. Notal organ of T3 flat rectangular, covering acute postnotal organ on anterior portion of T4. T4-T6 black brown. A6 projected on dorsal apex with long brown setae. A7 and A8 elongate, uniformly yellow, constricted basally. Genitalia (Fig. 14E-I Remarks. This new species resembles P. bashanicola in appearance, but can be readily differentiated from the latter by the following characters: (1) wing with apical band narrow (cf. absence); (2) 1A ending beyond (cf. before) the origin of Rs; (3) forewing usually longer than 13 mm (cf. shorter than 13 mm). Etymology. The specific name is dedicated to Yuan Hua, the collector of the type specimens.   16J-L): Subgenital plate broad subbasally, narrowed towards apex, with V-shaped terminal emargination, bearing long setae on distal third laterally. Medigynium with well-developed main plate, twice as long as wide; middle part bearing pair of lateral basal plates; posterior arms slender, half length of main plate, forming large, deep U-shaped emargination; axis elongated, bifurcated anteriorly, extended beyond main plate for half of its length, with posterior distinctly extruded.
Remarks. This new species resembles P. sexspinosa in appearance, but can be readily differentiated from the latter by: (1) meso-and metanotum unevenly black, bearing an indistinct narrow (cf. distinct) yellow mesal stripe; (2) basal spot greatly reduced (cf. absent); (3) hypovalve extremely slender (cf. broad); separated (cf. dense) long setae on inner margin; (4) middle (cf. basal) region of medigynium bearing a pair of lateral basal plates. Diagnosis. This species can be readily recognized by the following characters: (1) wing markings well-devel- oped, forewing apical band with two inner hyaline spots; pterostigmal band complete, with broad basal branch and thinly connected or detached apical branch; marginal spot large; basal band split into two spots; basal spot greatly reduced (Fig. 17A-B); (2) meso-and metanotum black, with broad pale mesal stripe (Fig. 17A-B); in males, (3) gonocoxites with cluster of long setae along slightly oblique inner apex ventrally (Fig. 17E); (4) parameres crossed mesally, twisted in S-shape (Fig. 17G); in females, (5) main plate of medigynium three times as long as posterior arms; axis extended beyond main plate for half of its length anteriorly (Fig. 17I-J). Description. Female: Head (Fig. 17B): Frons, vertex and occiput yellowish brown. Black transverse band passing through ocellar triangle, extending to inner margins of compound eyes. Rostrum yellow, slender, with labrum dark brown. Maxillary and labial palps mostly pale brown, with distal segments dark brown. Antennal scape yellowish brown; pedicel dark yellowish brown; flagellum blackish brown, filiform. Thorax (Fig. 17B): Pronotum black, with 12-16 stout setae along anterior margin. Meso-and metanotum black, with prominent pale yellow mesal stripe; scutella totally pale yellow. Pleura yellowish; legs yellowish brown, with distal tarsomere blackish. Wings (Fig. 17B): Membrane hyaline, with black brown markings. Forewing apical band with two hyaline spots inside; pterostigmal band complete, with broad basal branch and thinly connected or detached apical branch; marginal spot large; basal band split into two spots; basal spot greatly reduced between veins CuA and CuP. Abdomen (Fig. 17B): T2-T6 black. A7-A10 uniformly yellowish brown. Genitalia (Fig. 17H-J): Subgenital plate ligulate, bearing long setae on distal quarter. Medigynium with main plate oblong, broad; three times as long as posterior arms; pair of large wing-like lateral basal plates on basal half; axis slightly extruded posteriorly, extended beyond main plate for half of its length anteriorly.

Distribution. China: Sichuan.
Remarks. Panorpa jinchuana was described from two males from Jinchuan, Sichuan. The male and female specimens obtained from Danba, Sichuan match the characters of this species. Here, the female is described and illustrated for the first time.

Panorpa qinlingensis Chou & Ran, 1981
Panorpa qinliengensis Chou & Ran in Chou et al., 1981: 9, figs 30-33. Diagnosis. This species can be readily recognized by the following characters: (1) forewing with apical band broad, bearing large hyaline spot posteriorly; pterostigmal band complete, with broad basal branch and thin apical branch; marginal spot long and narrow or inconspicuous; basal band broad; basal spot extremely reduced or absent; (2) meso-and metanotum blackish brown with conspicuous yellowish mesal stripe; in males, (3) gonocoxites with triangular process on inner apex ventrally, bearing 1 or 2 long setae on inner margin subapically; (4) parameres crossed mesally, twisted in S-shape; in males, (5) medigynium with main plate almost oblong in shape, twice as long as wide; a pair of large basal plates reaching the middle of main plate; axis extended beyond main plate for two-fifths of its length anteriorly. Remarks. This species is bivoltine, overwintering in the prepupal stage in the soil. Adults emerge from mid-May to early June and from late July to mid-August in Liping, Shaanxi ).

Figs 18-19
Panorpa sexspinosa Cheng, 1949: 145, figs 4, 8, 9, 15 & 16 Diagnosis. This species can be readily recognized by the following characters: (1) wing markings well-developed, forewing apical band broad with large hyaline spot posteriorly; pterostigmal band with broad basal branch, and thin or no apical branch; marginal spot slender or absent; basal band broad; basal spot absent (Figs 18B-C, 19A-B); (2) meso-and metanotum blackish brown to black, with broad pale yellow mesal stripe (Fig. 19A-B); in males, (3) gonocoxites bearing 4-8 (usually 6) long setae along beveled inner apex ventrally (Fig. 19E-F); (4) parameres crossed mesally, twisted in S-shape, extending beyond gonocoxites (Fig. 19E, G); in females, (5) medigynium with main plate broad, pair of lateral basal plates reaching two-thirds length of main plate, each basal plate formed by three sclerotized structures connected by membrane; axis extended beyond main plate for onethird of its length anteriorly ( Fig. 19J-K).  Remarks. Panorpa sexspinosa zhongnanensis was described from Nanwutai, Shaanxi. Based on our observations, no significant differences from the nominotypical subspecies have been found in morphological characters, including body colour, wing markings, and male and female genitalia. Therefore, P. sexspinosa zhong-nanensis is here treated as a junior synonym of P. sexspinosa. Panorpa shanyangensis was described from a single female specimen from Cuipingshan, Shanyang, Shaanxi. It resembles P. sexspinosa in gross morphology, although it can be distinguished from the latter by three pairs (cf. a pair) of lateral basal plates, three spots, and incomplete apical band with three separated small spots near the inner margin (cf. apical band broad with a large hyaline spot posteriorly). After dissecting series of female specimens of P. sexspinosa from the type locality and other localities, we found that each complete basal plate is formed by three sclerotized structures connected by membrane. After comparing the female genitalia of P. shanyangensis and P. sexspinosa, we found these two nominal species share highly similar lateral basal plates and outline of the main plate. It is reasonable to consider that the apical band with three separated small spots near the inner margin in P. shanyangensis is variation of wing markings, thus P. shanyangensis and P. sexspinosa are very likely conspecific. Consequently, P. shanyangensis is treated as a junior subjective synonym of P. sexspinosa. In addition, according to the collection records, Panorpa sexspinosa is very likely a bivoltine insect in Shaanxi. Diagnosis. This species can be recognized by the following features: (1) frons, vertex, occiput and ocellar triangle black brown to black (Figs 20B-C, 21B-D); (2) wing membrane hyaline, with markings scattered into series of spots or only with pterostigma black brown in some males (Fig 21A-C); (3) pro-, meso-and metanotum blackish brown (Fig 20B-C); in males, (4) ventral termination of gonocoxites bearing 3-5 long setae and acute protuberance on inner apex (Fig. 21G); (5) param-eres crossed mesally, twisted in S-shape (Fig. 21G, I); in females, (6) main plate of medigynium broad, long, basal half narrow, distal half broad; small lateral basal plates on basal half not extended to the base; axis extended beyond main plate quarter of its length anteriorly, not extruded posteriorly ( Fig. 21K-L). (Figs 20B, 21A-B): Membrane hyaline, with markings dark brown to black brown. Wing markings variable: only with pterostigma in some males; scattered into series of spots in most individuals. Forewing apical band broad, split into series of spots arranged in two rows; pterostigmal band broad, complete anteriorly, scattered into series of small spots posteriorly; marginal spot represented by small rounded spot between R and M; basal band incomplete, reduced to irregular spot usually between CuA and CuP; basal spot usually faint or absent. Abdomen (Figs 20B, 21B, E): T2-T5 black. Notal organ of T3 covering acute postnotal organ of T4. A6 cylindrical with basal two-thirds black and distal one-third reddish brown. A7 and A8 yellowish brown, constricted basally. Genitalia (Fig.21E-I): Genital bulb oval, yellowish brown. Epandrium long, broad, slightly tapered towards deep square terminal emargination, bearing numerous long dense setae. Hypandrium with shortened basal stalk and pair of hypovalves; hypovalves broadened from middle, extending to four-fifths length of gonocoxites, bearing row of long black bristles along inner margin of distal half. Gonocoxite bearing 3-5 long setae on inner apex ventrally, inner margin bearing acute protuberance. Gonostylus with obtuse triangular median tooth and large basal cup on inner margin. Parameres crossed, reaching apex of gonocoxites. Dorsal valves of aedeagus with enlarged dorsal process on subapical portion dorsally. Ventral valves greatly shortened. Lateral processes distinct, triangular.
Remarks. This species was described from a single female specimen from Chishui, Guizhou with promient scattered wing markings. The specimens obtained from Yunnan match the characters of P. stigmosa. Here, the male of this species is described for the first time.
Panorpa uncinata sp. nov. Fig. 22 Diagnosis. The new species can be recognized by the following features: (1) forewing with broad apical band occasionally bearing two inner hyaline spots; pterostigmal band with broad basal branch and thin apical branch; marginal spot narrow or reduced; basal band broad; basal spots extremely reduced and faint (Fig. 22A-B); (2) meso-and metanotum black, with narrow yellow brown mesal stripe (Fig. 22A-B); (3) gonocoxites with approximately four stout setae on inner apex ventrally (Fig. 22F); (4) paramere intensively curved, hook-like on apical half, reaching two-thirds of gonocoxite (Fig. 22G); (5)  Measurements. Male: FL = 12.1-12.9 mm, FW = 3.2-3.4 mm; HL = 10.9-11.5 mm, HW = 3.1-3.3 mm. Female: FL = 12.1-13.6 mm, FW = 3.1-3.4 mm; HL = 11.0-12.3 mm, HW = 2.9-3.2 mm. (Fig. 22A, C): Frons, vertex and occiput yellowish brown. Black band through ocellar triangle not extending to compound eyes. Rostrum yellow, with labrum dark brown. Maxillary and labial palps mostly brown, with distal segments dark brown. Antennal scape yellowish brown basally and dark brown apically; flagellum dark brown, filiform, with 33-38 flagellomeres. Thorax (Fig. 22A, D): Pronotum black, with 10-12 stout setae along anterior margin. Meso-and metanotum black, with narrower yellow brown mesal stripe; scutella yellow brown. Pleura pale yellow. Legs light yellowish brown, with distal tarsomere blackish. Wings (Fig. 22A): Membrane hyaline, with markings dark brown. Forewing with apical band broad, bearing one or two hyaline spots, smaller one between R 2b and R 3 , and larger one between R 5 and M 2 ; pterostigmal band complete, with basal branch approximately twice as wide as apical branch; marginal spot variable: slender; split into two spots, not extended to M; or greatly reduced in some individuals; basal band broad; basal spots greatly reduced. Hindwing similar to forewing in coloration and pattern, but with marginal and basal spots much reduced, apical band usually bearing one hyaline spot in posterior portion. Abdomen (Fig. 22A, D): T2-T5 black brown to black. Notal organ of T3 flat triangular, covering acute postnotal organ on T4. A6 with basal two-thirds black, distal third yellow, projected and setose on dorsal apex. A7 and A8 uniformly yellow, slightly constricted basally. Genitalia (Fig. 22E-I): Genital bulb elliptical, yellow. Epandrium broad, with deep terminal emargination, bearing numerous setae. Cercus clavate, yellow brown basally and dark brown distally. Hypandrium with shortened basal stalk and pair of hypovalves; hypovalves broad, with basal half narrower, extending to three-quarters length of gonocoxites, bearing row of long bristles along inner margin. Gonocoxite mostly with four stout setae on inner apex ventrally. Gonostylus with obtuse triangular median tooth and large basal cup. Parameres slender, crossed mesally, intensively curved, hook-like, reaching two-thirds length of gonocoxites. Dorsal valves of aedeagus elongate, each with enlarged dorsal process on subapical portion dorsally. Ventral valves shortened. Lateral processes distinct, triangular. -Female: Similar to male in wing markings (Fig. 22B). Genitalia (Fig. 22J-L): Subgenital plate ligulate, narrow basally, broadest medially, and narrowed towards apex, with shallow V-shaped terminal emargination, bearing long setae on caudal and lateral margins. Medigynium with well-developed broad main plate. Pair of lateral basal plates extended from base to middle of main plate. Posterior arm one-third length of main plate, forming broad U-shaped emargination. Axis bifurcated, elongated, extended anteriorly beyond main plate for half of its length, with posterior slightly extruded. Remarks. This new species resembles P. yangi, especially in the intensively curved, hook-like parameres, but can be readily differentiated from the latter by: (1) meso-and metanotum black, bearing a narrow (cf. very broad) yellow mesal stripe; (2) basal spots extremely reduced and faint (cf. large and distinct).

Panorpa yangi Chou, 1981
Panorpa yangi Chou in Chou et al., 1981: 8, figs 24-27 Diagnosis. This species can be recognized from by the following features: (1) forewing with broad apical band bearing one hyaline spot posteriorly; pterostigmal and basal bands complete, broad; marginal and basal spots large, conspicuous (2) meso-and metanotum mostly yellowish brown and anterior margin blackish brown laterally; in males, (3) ventral termination of gonocoxites wavy, bearing 3-6 long setae on inner portion; (4) parameres very slender, intensively curved, hook-like on apical halves, reaching two-thirds length of gonocoxites; in females, (5) main plate of medigynium approximately rectangular, twice as long as wide; a pair of simple lateral basal plates extending from base to middle of main plate; axis extended beyond main plate for two-thirds of its length anteriorly.

Distribution. China: Shaanxi.
Remarks. This species resembles P. neospinosa in wing markings, but can be differentiated from the latter by meso-and metanotum mostly yellowish brown (cf. blackish brown with pale yellow mesal stripe) and hook-like (cf. S-shaped) parameres. Panorpa yaoluopingensis sp. nov. Fig. 23 Diagnosis. This species can be readily recognized by the following characters: (1) forewing with apical band broad, bearing large hyaline spot on posterior margin; pterostigmal band with basal branch broad, and apical branch greatly reduced; basal band reduced into large spot near anal margin; marginal spot absent or as 1-3 small spots (Fig. 23A-B); (2) meso-and metanotum blackish brown, with prominent pale yellow mesal stripe (Fig. 23A-B); in males, (3) inner apex of gonocoxites oblique, with 6-8 dark brown setae (Fig. 23E); (4) parameres twisted in S-shape, crossed mesally ( Fig. 23E-F); in females, (5) medigynium with broad main plate and pair of lateral basal plates on middle portion; posterior arms one-third as long as main plate, axis extended beyond main plate for half of its length, with posterior slightly extruded ( Fig. 23J-K).
Etymology. The specific name refers to the type locality, Yaoluoping, Yuexi, Anhui. Measurements. Male: FL = 11.4-12.0 mm, FW = 2.9-3.1 mm; HL = 10.3-11.2 mm, HW = 2.8-3.0 mm. Female: FL = 11.3-12.1 mm, FW = 3.1-3.2 mm; HL = 10.1-11.1 mm, HW = 3.0-3.1 mm. (Fig. 23A, C): Frons, ocellar triangle, vertex and occiput dark blown. Rostrum yellowish; labrum yellowish brown. Labial and maxillary palps yellowish basally, gradually darkening toward apex, with apical segment dark brown. Antennal scape yellowish brown; flagellum brownish black, filiform with 39-42 flagellomeres. Thorax (Fig. 23A, D): Pronotum dark brown, with 10-14 black setae along anterior margin; meso-and metanotum dark brown, with pale yellow fusiform mesal stripe; scutella pale yellow. Pleura yellow. Legs yellowish brown, with distal tarsomere dark brown. Wings (Fig. 23A): Membrane hyaline, with brown markings. Forewing with apical band broad, bearing large hyaline spot on posterior margin; pterostigmal band with basal branch broad and apical branch greatly reduced; marginal spot absent or divided into 1-3 small spots; basal band reduced into large spot from M to anal margin; basal spot absent. Hindwing similar to forewing, but with relatively reduced markings. Marginal spot absent or faint; basal band smaller, usually not reaching anal margin. Abdomen (Fig. 23A, D): T2-T5 dark to black brown. Notal organ of T3 flat, covering acute postnotal organ on T4. A6 dark brown on basal two-thirds and yellow distally, projected on dorsal apex, with sparse long yellow setae. A7 and A8 elongate, uniformly yellow, constricted basally. Genitalia (Fig. 23E-G): Genital bulb oval, yellow. Epandrium broad basally, with square, deep terminal emargination, bearing dense setae distally. Cercus long clavate, slightly expanded towards apex. Hypandrium with shortened basal stalk, with pair of long strip-like hypovalves; each hypovalve rounded at apex, bearing long bristles along apical half on inner margin, not reaching apex of gonocoxites. Inner margin of gonocoxite oblique apically, with 6-8 stout setae. Gonostylus with large basal cup and obtuse triangular median tooth on inner margin. Parameres twisted in S-shape, crossed mesally, bearing dense short spines on inner margin and whole distal portion, with apex pointed. Aedeagus with ventral valves greatly shortened; dorsal valves greatly elongated, strongly curved dorsally, constricted basally and expanded towards rounded apex; bearing bundle of long hairs ventrally on basal third and enlarged dorsal process near middle. Lateral process distinctly triangular. -Female: Similar to male in wing patterns (Fig.  23B). Genitalia (Fig. 23H-K): Subgenital plate broad subbasally, narrowed towards apex, bearing long setae on caudal and lateral margins. Medigynium with broad main plate, pair of lateral basal plates on middle portion; posterior arms one-third as long as length of main plate, forming "water drop"-shaped emargination; axis with pair of small sclerotized structures near central position of main plate, extended beyond main plate for approximately half of its length, with posterior slightly extruded.

Distribution. China: Anhui.
Remarks. This new species resembles P. huayuani and P. sexspinosa in general appearance, but can be readily differentiated from the latter two species by the following characters: (1) wing markings with basal band reduced into a large spot extending from M to anal margin in forewing (cf. complete); (2) occiput dark brown (cf. yellowish brown).
The phylogenetic trees are similar in topology between the MP and ML analyses, although the ML tree (Fig. 25) has higher support values than the strict consensus tree of the MP trees. The ML tree shows that the P. davidi group is a well-supported monophyletic group (MLBS = 94) and is sister to Cerapanorpa (MLBS = 95). The incongruence between the analyses is restricted to the relationship of some species of the P. davidi group.    (Figs 24-25). The Chinese species of Panorpa without anal horn in males were previously treated as the P. davidi group, which is here reconfirmed to be paraphyletic, since they are scattered on the phylogenetic tree of the Panorpidae (Figs 24-25). Panorpa sibirica and P. communis are well-supported sister taxa, distant from the newly defined P. davidi group.

Discussion
In the present study, phylogenetic reconstruction was conducted for all the eight genera of Panorpidae based on 79 morphological characters. The P. davidi group sensu Carpenter (1938) and Cheng (1949Cheng ( , 1957 is reconfirmed to be a paraphyletic group. Panorpa davidi and 20 species are clustered into a well-supported monophyletic clade, sister group to Cerapanorpa. In the present study we newly defined the P. davidi group based on morphol-   ogy and phylogeny. Four new species are described and two synonyms are proposed. Consequently, 21 species are currently recognized in the P. davidi group. In a morphological phylogenetic analysis, Ma et al. (2012) found that three species of the P. davidi group (P. chengi, P. fulvastra, and P. sexspinosa) did not form a monophyletic group, possibly owing to insufficient characters encoded. In contrast molecular phylogenetic analyses by Hu et al. (2015) and Miao et al. (2019) found six species of this group formed a monophyletic group. Based on our present phylogenetic study, the monophyly of the newly defined P. davidi group is confirmed.
Previously, the P. davidi group sensu Carpenter (1938) and Cheng (1949Cheng ( , 1957 consisted of the Chinese species that lack the anal horn in males. Herein, however, we assign only 21 species to the P. davidi group. These species share a similar morphology, especially the male and female genitalia. According to recent phylogenetic analyses (Hu et al. 2015;Miao et al. 2017Miao et al. , 2019Jiang et al. 2019;Wang and Hua 2020), this new definition of the P. davidi group constitutes a well-supported monophyletic group, sister to Cerapanorpa.
The species of the P. davidi group are normally found in the groundcover of moist forests in mountainous regions, with a broad spectrum of elevations. Panorpa difficilis inhabits ranges from 230 to 2050 m in elevation, whereas P. fructa is found only at high-altitude from 3300 to 4000 m in the Hengduan Mountains, exhibiting strong cold-adaptation. The P. davidi group not only exhibits a discrete distribution in the Taihang and Dabie Mountains, but also displays a circular distribution pattern around the Sichuan Basin, similar to that of Dicerapanorpa (Hu and Hua 2020). It would be a fascinating issue to explore the distribution pattern and mechanism in future research.