Revision of the Chaetocnema picipes species-group (Coleoptera, Chrysomelidae, Galerucinae, Alticini) in China, with descriptions of three new species

Abstract The Chinese Chaetocnema picipes species-group is revised. It contains 5 species including 3 new species: C. cheni sp. n., C. constricta sp. n. and C. kingpinensis sp. n. The lectotype of C. fortecostata is designated. A key to all known species of this group from China and the illustrations of habitus and genitalia are provided. A distribution map of species is given.

introduction Chaetocnema Stephens, 1831 is a cosmopolitan flea beetle genus with over 400 species known to world (Konstantinov et al. 2011). About 40 species are known to China. Nearctic, Palearctic and Afrotropical faunas of the genus have recently been revised (White 1996, Biondi and D'Alessandro 2006, 2010, Konstantinov et al. 2011, however Chinese Chaetocnema species remained mostly unknown. Two distinct subgenera of Chaetocnema are recognized in the Palearctic. They are separated based on the following characters: relative width of the frontal ridge and density and size of punctures on vertex. Since a distinguishing power of these characters weakens significantly in more southern faunas (Biondi 2002, Konstantinov et al. 2011, identification of the subgenera becomes problematic. However, as in many other species rich flea beetle genera (e.g. Aphthona Chevrolat), distinct species groups may be recognized in Chaetocnema. One of these groups in China is the picipes species-group. Five distinct species here attributed to this group share the following characters: 5-7 punctures on vertex close to each eye, two short obscure longitudinal strips without punctures on the base of pronotum, punctures on elytra are arranged in lines, median lobe of aedeagus without deep groove or wrinkles on the ventral surface, apex of aedeagus without obvious denticle, pearshaped spermatheca.
Chaetocnema species of the picipes group are usually found in the field feeding on Rubus, Polygonum and Solanum.
We studied all the specimens in IZCAS previously identified as C. concinna (Marsham) from different provinces of China. It turned out that they are indeed C. picipes, C. fortecostata sp. n. or C. constricta sp. n. Chaetocnema concinna is not found in China and all the published records of it in China should be treated as misidentifications.

Materials and methods
The female genitalia were dissected and mounted onto slides with Hoyer's medium, photos were taken with digital camera NIKON 5200D attached to the ZEISS AXI-OSTAR PLUS Microscope. The photos of habitus were taken with the 5× lens of the same microscope with extra light source softened by semitransparent paper, so as to observe the real color of these tiny beetles. The photos of aedeagus were taken with the KEYENCE VHX-600 microscope. Scanning electron micrographs were taken with FEI QUANTA 450. A map of species distribution was generated by ARCGIS software. Descriptions of species were initially generated by LUCID software, exported from it and extensively edited.
Morphological terminology follows Konstantinov et al. (2011). Places of distribution of this article are arranged from north to south provinces names in "Materials" paragraphs are in bold font. Color of elytra, pronotum and head consistently copperish. Antennomere 1 partly dark brown. Antennomeres 2-3 yellow. Antennomere 4 yellow or partly brown. Antennomere 5 partly brown. Remaining antennomeres black. Pro-and mesofemora brown with yellow on the apex. Metafemora brown. Tarsi brown with yellow on base of each tarsomere. Base of pronotum with two short, obscure longitudinal impressions without punctures near basal margin. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Pronotal base evenly convex. Lateral sides of pronotum slightly convex with maximum width near base. Anterolateral prothoracic callosity protruding laterally forming round angle. Posterolateral prothoracic callosity projects up to lateral margin of pronotum. Diameter of pronotal punctures 2 to 4 times smaller than distance between them.
Elytra with convex sides. Scutellar row of punctures on elytron regular and single. Remaining rows of punctures regular. Elytral humeral calli well developed. Interspaces between rows of punctures smooth and glabrous. Two lines of minute punctures on each interspace.
Head hypognathous. Frontal ridge between antennal sockets narrow and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above the antennal socket) deep, but rather narrow. Width of frontal ridge to width of antennal socket: 0.900-1.005. Width of orbital sulcus to width of frontolateral sulcus: 0.611-0.614. Surface of vertex sparsely and unevenly covered with 6-7 punctures near each eye. Numbers of punctures on each orbit: 2-3. Numbers of setae along frontolateral sulcus on each side: 8-10. Numbers of setae on frons (triangular area surrounded by frontolateral sulci and clypeus): 0. Numbers of setae on clypeus: 7. Numbers of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.
Median lobe of aedeagus parallel-sided with apical third slightly widening. Apical part of median lobe in ventral view narrowing abruptly. Ventral longitudinal groove of median lobe absent in apical part and poorly developed in middle and basal part. Apical denticle of aedeagus in ventral view poorly differentiated, straight in lateral view. Minute transverse wrinkles on ventral side of median lobe absent. Median lobe in lateral view narrow and evenly curved. Width (in middle) to length of median lobe (in ventral view) about 0.15.
Spermathecal receptacle pear-shaped. Spermathecal pump much shorter than receptacle. Apex of spermathecal pump cylindrical. Spermathecal pump attached to middle of receptacle top. Maximum width of receptacle situated basally. Basal part of receptacle wider than apical. Posterior sclerotization of tignum spoon-shaped, wider than mid section. Anterior sclerotization of tignum wider than mid section. Apex of vaginal palpus subdeltoid, with lateral side slightly arching. Sides of middle part of vaginal palpus (before apex) narrowing from base, slightly widening towards apex. Anterior sclerotization of vaginal palpus slightly widening anteriorly. Anterior sclerotization of vaginal palpus slightly and evenly curved along length. Anterior end of anterior sclerotization broadly rounded. Length of posterior sclerotization greater than width. Posterior sclerotization about as wide as anterior sclerotization. Remarks. This species was recently revised by Booth and Owen (1997) and Konstantinov et al. (2011), and we follow the species status of these two thorough revisions.

Materials (all the materials preserved in IZCAS
We did not find any C. picipes specimens from South China, it seems that C. picipes is distributed only in the Palaearctic part of China. The southern boundary of the distribution of C. picipes is the Qingling Mountain which is also a southern boundary of many other Palaearctic faunistic elements (Yang 2005). We have collected C. picipes from several places from the north slope of Qinling Mountain during several expeditions, but we did not find any from the south slope. It is also interesting that the specimens collected from Qinling Mountain look darker, the color of the body, appendages, antennomeres and male genitalia are darker than other specimens from other places of northern China.
Head hypognathous. Frontal ridge between antennal sockets narrow and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above antennal socket) obscure and narrow. Width of frontal ridge to width of antennal socket: 0.56-0.66. Width of orbital sulcus to width of frontolateral sulcus: 0.71±0.05. Surface of vertex sparsely and unevenly covered with 5-6 punctures near each eye. Numbers of punctures on orbit: 1-2 on each side. Numbers of setae along frontolateral sulcus: 5-6 on each side. Numbers of setae on frons (triangular area surrounded by frontolateral sulcus and clypeus): 0. Numbers of setae on clypeus: 5. Numbers of setae on labrum: 6. Anterior margin of labrum slightly convex in middle.
Base of pronotum with two short, obscure longitudinal impressions without punctures near basal margin. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Shape of pronotal base evenly convex. Lateral sides of pronotum slightly convex with maximum width near base. Anterolateral prothoracic callosity protruding laterally forming strong round angle. Posterolateral prothoracic callosity projects up to lateral margin of pronotum. Diameter of pronotal punctures 2 to 4 times smaller than distance between them.
Elytra with convex sides. Scutellar row of punctures regular and single. Remaining rows regular. Elytral humeral calli well developed. Interspace smooth and glabrous. 2 lines of minute punctures on each interspace.
First male protarsomere, length to width ratio: 1.65±0.05. First and second male protarsomeres, length to length ratio: 1.94-2.24, width to width ratio: 1.42-1.45. First male protarsomere, width at apex to width at base: 1.60-1.75. Length of metatibia to distance between denticle and metatibial apex: 2.80-2.90. Large lateral denticle on metatibia sharp. Metatibial serration proximal to large lateral denticle present, obtuse. Metatibia proximad to denticle in dorsal view concave. First male metatarsomere, length to width ratio: 3.60-3.67. First and second male metatarsomeres, length to length ratio: 1.87-1.93, width to width ratio: 0.83. Third and fourth male metatarsomeres, length to length ratio: 0.60-0.65. Metatibia length to metafemora length: 0.76±0.05. Length of hind leg to length of body: 0.87±0.05. Spermathecal receptacle pear-shaped. Spermathecal pump much shorter than receptacle. Apex of spermathecal pump cylindrical. Spermathecal pump attached to middle of receptacle top. Maximum width of receptacle situated basally. Basal part of receptacle wider than apical. Posterior sclerotization of tignum spoon-shaped, wider than mid section. Anterior sclerotization of tignum narrower than mid section. Apex of vaginal palpus subdeltoid, with lateral side slightly arching. Sides of mid part of vaginal palpus (before apex) narrowing from base, widening towards apex. Anterior sclerotization of vaginal palpus slightly widening anteriorly. Anterior sclerotization of vaginal palpus slightly and evenly curved along length. Anterior end of anterior sclerotization broadly rounded. Length of posterior sclerotization greater than width. Posterior sclerotization about as wide as anterior.
Type materials (preserved in IZCAS Remarks. There is no holotype or paratype in the IZCAS. But we found eight specimens belonging to what looks like a type series of this species labeled as "C. fortecostata sp. n." with Chen's handwriting. The locality on the label corresponds with the original description. Therefore we consider these eight specimens as the syntypes. Here we designate one male as the lectotype and the remaining seven as paralectotypes. This species only occurs in the Oriental China while the northernmost specimens were found on the southern slopes of Qinling Mountain, which is considered as a border between Palearctic and Oriental Regions within China (Chen 1997;Yang 2005).
Distribution. Hunan, Jiangxi, Sichuan, Yunnan. Host plants. Solanum tuberosum Linn. (Solanaceae). Diagnosis. Chaetocnema cheni sp. n. can be differentiated from C. kingpinensis sp. n. and C. constricta sp. n. by the following characters: first male protarsomere clearly larger than second, appendages darker in color, anterolateral angles of pronotum round. Chaetocnema cheni can be differentiated from C. picipes and C. fortecostata based on the following characters: metatibia proximad to denticle in dorsal view convex, apex of aedeagus subdeltoid, tip of aedeagus widely rounded.
Description Color of elytra usually same with or slightly different from pronotum. Color of elytra copperish, sometimes bluish black. Color of pronotum copperish, sometimes bronzish. Head dorsally copperish, sometimes bluish black. Antennomere 1 partly dark brown. Antennomeres 2-3 yellow. Antennomeres 4-5 partly brown. Remaining antennomeres black. Pro-and mesofemora brown with yellow apex. Metafemora brown. Tarsi brown with yellow on base of each tarsomere.
Head hypognathous. Frontal ridge between antennal sockets narrow and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above antennal socket) deep. Width of frontal ridge to width of antennal socket: 1.19±0.05. Width of orbital sulcus (above antennal socket) to width of frontolateral sulcus: 0.64-0.67. Surface of vertex sparsely and unevenly covered with 6-7 punctures close to each eye. Numbers of punctures on orbit on each side: 1. Numbers of setae along frontolateral sulcus on each side: 9-10. Numbers of setae on frons (triangular area surrounded by frontolateral sulcus and clypeus): 0. Numbers of setae on clypeus: 7. Numbers of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.
Base of pronotum with two short, obscure longitudinal impressions near basal margin. Longitudinal impressions lack punctures. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Shape of pronotal base evenly convex. Anterolateral prothoracic callosity protruding laterally but poorly developed. Posterolateral prothoracic callosity projects up to lateral margin of pronotum. Diameter of pronotal punctures 2 to 4 times smaller than distance between them. Elytra with convex sides. All rows of punctures on elytron regular and single. Elytral humeral calli well developed. Interspaces of puncture rows smooth and glabrous. Numbers of minute punctures lines on each interspace: 2.
Median lobe of aedeagus widening gradually towards apex. Apical part of median lobe in ventral view narrowing abruptly forming a subdeltoid apex. Ventral surface of median lobe lateral to median groove apically convex. Ventral longitudinal groove absent in apical and middle part, shallow in basal. Apical denticle of aedeagus in ventral view absent. Apical part of aedeagus in lateral view slightly curved ventrally. Minute transverse wrinkles on ventral side of median lobe absent. Median lobe in lateral view slightly sinusoidal near apex. Median lobe narrow in lateral view. Maximal curvature of median lobe in lateral view situated medially. Width (in middle) to length of median lobe (in ventral view) about: 0.14.
Spermathecal receptacle pear-shaped. Spermathecal pump much shorter than receptacle. Apex of spermathecal pump cylindrical. Spermathecal pump attached to middle of receptacle top. Maximum width of receptacle situated basally. Basal part of receptacle wider than apical. Posterior sclerotization of tignum spoon-shaped, wider than mid section. Anterior sclerotization of tignum wider than mid section. Apex of vaginal palpus subdeltoid, with lateral side slightly arching. Sides of mid part of vaginal palpus (before apex) narrowing from base, slightly widening towards apex. Anterior sclerotization of vaginal palpus slightly widening anteriorly, slightly and evenly curved along length. Anterior end of anterior sclerotization nearly flat. Length of posterior sclerotization greater than width. Width of posterior sclerotization greater to anterior sclerotization.
Remarks. There is a noticeable variability in body color among studied specimens. The holotype collected from Longling, Yunnan province is copperish in color, but the paratypes from Jinfou Mountain, Sichuang Province have greenish-bronzish pronotum and blue-blackish elytra.
Diagnosis. Body of Chaetocnema constricta sp. n. usually tiny and narrow. It can be differentiated from C. picipes, C. fortecostata sp. n. and C. cheni sp. n. by the following characters: first male protarsomere only slightly larger than second, appendages light in color, anterolateral angles of pronotum obtuse and thickened. Exteriorly this species resembles C. kingpinensis. But C. kingpinensis is larger in body size, having longer appendages and pronotum (relative to body length). If viewed under a soft light, C. constricta's body is entirely bronzish, while C. kingpinensis has usually bronzish pronotum and blackish brown elytra.
Head hypognathous. Frontal ridge between antennal sockets narrow and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above the antennal socket) very deep. Orbital sulcus forming an obvious narrow deep concave above orbit. Width of frontal ridge to width of antennal socket: 0.70-0.75. Width of orbital sulcus (above antennal socket) to width of frontolateral sulcus: 1.20-1.45. Surface of vertex sparsely and unevenly covered with 5-6 punctures on each side close to eye. Numbers of punctures on orbit on each side: 1-2. Numbers of setae along frontolateral sulcus on each side: 9-10. Numbers of setae on frons (triangular area surrounded by frontolateral sulci and clypeus): 0. Numbers of setae on clypeus: 4. Numbers of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.
Base of pronotum with two short longitudinal impressions visible only near basal margin. Longitudinal impressions lack punctures. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Pronotal base evenly convex. Anterolateral prothoracic callosity has finely developed blunt angle protruding antero-laterally. Posterolateral prothoracic callosity projects beyond lateral margin of pronotum. Diameter of pronotal punctures subequal to distance between them.
Elytra with convex sides. Scutellar row of punctures regular and single. Remaining rows regular. Elytral humeral calli well developed. Interspaces of rows of punctures smooth and glabrous. Two lines of minute punctures on each interspace.
First male protarsomere slightly larger than second. First male protarsomere, length to width ratio: 1.90-2.00. First and second male protarsomeres, length to length ratio: 1.60-1.80, width to width ratio: 1.05-1.13. First male protarsomere, width at apex to width at base: 1.70-1.88. Length of metatibia to distance between denticle and Etymology. We named this species after a place called "Kingpin" in Yunnan province where some specimens of this species were collected.
Distribution. Jiangxi,Yunnan, Guangxi. Host plants. Rubus sp. (Rosaceae). Diagnosis. Body of Chaetocnema kingpinensis sp. n. quite narrow. It can be differentiated from C. picipes, C. fortecostata sp. n. and C. cheni sp. n. by the following characters: first male protarsomere only slightly larger than second, appendages light in color, anterolateral angles of pronotum obtuse and thickened. This species resembles C. constricta exteriorly. But C. kingpinensis is lager in body size, with longer appendages and pronotum (relative to body length). If viewed under a soft light, C. constricta appears entirely bronze, while C. kingpinensis usually has bronzish pronotum and blackish brown elytra.
Head hypognathous. Frontal ridge between antennal sockets narrow and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above antennal socket) deep. Width of frontal ridge to width of antennal socket: 0.84-0.88. Width of orbital sulcus (above antennal socket) to width of frontolateral sulcus: 0.93-1.16. Surface of vertex sparsely and unevenly covered with 5-6 punctures close to each eye. Numbers of punctures on orbit on each side: 3-5. Numbers of setae along frontolateral sulcus on each side: 8-10. Numbers of setae on frons (triangular area surrounded by frontolateral sulcus and clypeus): 0. Numbers of setae on clypeus: 7. Numbers of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.
Base of pronotum with two short longitudinal impressions without punctures visible only near basal margin. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Pronotal base evenly convex. Lateral sides of pronotum thickened, only slightly convex with maximum width near base. Pronotum quite convex from lateral view. Anterolateral prothoracic callosity protruding antero-laterally, forms strong obtuse angle. Posterolateral prothoracic callosity projects beyond lateral margin of pronotum. Setae on each callosity long, exceeding half of pronotal length. Wrinkles between punctures on pronotum well developed. Diameter of pronotal punctures subequal to distance between them.
Elytra with convex sides. Scutellar row of punctures regular and single. All other rows of punctures regular. Elytral humeral calli well developed. Interspaces between rows of punctures on elytra smooth and glabrous. Numbers of minute punctures lines on each interspace: 2.
Apical third of median lobe of aedeagus parallel-sided. Apical part of median lobe in ventral view narrowing abruptly. Ventral longitudinal groove of median lobe poorly developed in apical and basal part, narrow or absent in middle part. Apical part of longitudinal groove as wide as basal. Apical denticle of aedeagus in ventral view poorly differentiated. Apical denticle of aedeagus in lateral view strongly curved ventrally. Minute transverse wrinkles absent on ventral side of median lobe. Median lobe in lateral view slightly sinusoidal near apex. Maximal curvature of median lobe in lateral view situated medially. Width (in middle) to length of median lobe (in ventral view) about: 0.18. Median lobe narrow in lateral view.
Spermathecal receptacle pear-shaped, slightly narrow in middle. Spermathecal pump much shorter than receptacle. Apex of spermathecal pump cylindrical. Spermathecal pump attached to middle of receptacle top. Maximum width of receptacle situated basally. Basal part of receptacle wider than apical. Posterior sclerotization of tignum spoon-shaped, wider than mid section. Mid section of tignum nearly straight. Anterior sclerotization of tignum wider than mid section. Apex of vaginal palpus subdeltoid, with lateral side slightly arching. Sides of mid part of vaginal palpus (before apex) narrowing from base, slightly widening towards apex. Anterior sclerotization of vaginal palpus slightly narrowing anteriorly. Anterior sclerotization of vaginal palpus slightly and evenly curved along length. Anterior end of anterior sclerotization broadly rounded. Length of posterior sclerotization greater than width. Posterior sclerotization about as wide as anterior sclerotization.
The specimens of this species collected from Tianping Mountain are extremely large. One male from Guanxi, is 2.54 mm long, and female can be as long as 2.64 mm.

Distribution pattern of species of Chinese Chaetocnema picipes species-group
Qinling Mountain, considered as a border between Palearctic and Oriental Regions within China (Chen 1997;Yang 2005) seems a natural barrier which separate the Palaearctic species from the Oriental ones. It is also applicable in this species-group. C. picipes is distributed only in the Palaearctic part of China while C. fortecostata is distrib- uted only in Oriental China. It is interesting that some of the southernmost specimens of C. picipes were collected from several places from the north slope of Qinling Mountain but none from the south slope. The northernmost specimens of C. fortecostata we found are from the southern slopes of Qinling Mountain.
C. cheni sp. n. seems to be a species in the transition area between Oriental and Palaearctic Region, however C. fortecostata, C. constricta and C. kingpinensis are the Oriental ones.