小异长足虻属额宽率的进化意义及一新属五新种记述(双翅目,长足虻科,异长足虻亚科)

研究发现小异长足虻属Chrysotus Meigen,1824中某些类群所具备的"额渐次变狭,颜颇宽、略下凹、两侧缘平行"的额、颜构造特征与异长足虻属Diaphorus Meigen,1824完全相同,该特征在两者中应属系统发育特征;并主要据此特征将小异长足虻属中凡具备"额渐次变狭,颜颇宽、略下凹、两侧缘平行"特征的类群分离出来,建立了变长足虻属Dubius gen.nov.,并附新属5新种记述:秋变长足虻D.autumnalus sp.nov.,曲变长足虻D.curtus sp.nov.,额变长足虻D.frontus sp.nov.,红崖变长足虻D.hongyaensis sp.nov.和亚曲变长足虻D.succurtus sp.nov.。根据变长足虻属,仅分布于新热带区和属东洋区的中国西南地区推测其可能起源于南方古陆(冈瓦纳古陆),并早在冈瓦纳大陆裂解前即向东洋区扩散。模式标本保存于作者所在单位。

THE EVOLUTIONARY SIGNIFICANCE ON FR/FA RATIO OF CHRYSOTUS MEIGEN ( DIPTERA, DOLICHOPODIDAE,DIAPHORINAE), WITH DESCRIPTIONS OF ONE NEW GENUS AND FIVE NEW SPECIES

In the present paper,a group of species separated from Chrysotus M eigen,1824 is establishied as new genus,Dubius gen.nov.,of which five new species from Guizhou,Southwestern China are described:D.autumnalus sp.nov.,D.curtus sp.nov.,D.frontus sp.nov.,D.hongyaensis sp.nov.and D.succurtus sp.nov.It may be reasonable conjecture that Dubius gen.nov.derives from the Southern land(Gondwana land) and spreads to Oriental Region because the new genus is only found in Neotropical Realm and Southwestern China belonging to Oriental Region.Dubius gen.nov.Size small.Antenna black,is situated at mid and lower part of head.First fragellomere short and small,length shorter than width.Arista apically,short pubescent.6 dc.Irregularly paired acr short and hairlike.Scutellum with 2 pairs of bristles,basal pair short and hair-like.Propleuron with 1 black hair and 1 black bristle on lower part.M id and hind coxae each with 1 outer bristle.Claws usually present.Pulvilii as a rule undeveloped.R4 +5 and M parallel apically.CuAx ratio more than 0.3(the individual distributed in Neotropical Region with CuAx ratio reaching up to 0.7).Halter yellow to dark yellow,individual brownish black.T g6 with setulae.St8 without strong long bristles.Epandrium round posteriorly.Surstylus usually tapering and slightly curved apically,but Neotropical ones remarkably straight.Cercus is small lob-like,unfurcated.Lateral epandrial lobe developed.Hypandrium usually expanded and with process apically.T ype species:Dubius curtus sp.nov.T he new genus is allied to Chrysotus M eigen,1824,but differs in:1) body larger;2) the formation of frons and face as in Diaphorus M eigen,1824(frons narrow,and face wider,slightly concaved and parallelsided,fr /fa ratio usually less than 1.0) ;3) antennae issituated at mid and lower part of head.Etymology.T he new genus name is from the Latin word "Dubius",in reference to the variation of frons.Key to the species of Dubius gen.nov.1.Fr /fa ratio more than 1.0.Antennae is situated at mid and upper part of head.Arista apical.W ing small size,anal field undeveloped.M ale:T g6 setulose.St8 without strong long bristles.Lateral epandrial lobe usually developed.Epandrial lobe absent.Claws generally present.Pulvilii usually undeveloped ……Chrysotus Meigen,1824 Fr /fa ratio less than or equal to 1.0;not with the above combination of characters …………………………………………………………2 2.Arista dorsal.W ing large sized,anal field developed.M ale:T g6 bare.St8 with 2-8 strong long bristles.Lateral epandrial lobe absent.Epandrial lobe developed.Claws small or absent.Pulvilii developed …………………………………Diaphorus Meigen,1824 Arista apical.W ing small sized,anal field undeveloped.M ale:T g6 setulose,St8 without strong long bristles.Lateral epandrial lobe developed.Epandrial lobe absent.Claws and pulvilii usually present(Dubius gen.nov.) ………………………………………………3 3.Fr /fa ratio equal to 1.0.Pulvilii usually undeveloped ……………4 Fr /fa ratio less than 1.0.Pulvilii usually developed ………………5 4.Frons and face as narrow as line.W ing and T g2-5 without spot.M ale with lateral epandrial lobe developed D.autumnalus sp.nov.………………………… ………………………………………… Frons and face equal in width,broad,around 1.5 times higher than broad.W ing with a transverse brown spot.T g2-5 with lateral yellow spots.M ale with lateral epandrial lobe undeveloped D.maculatus(Parent,1930) ……… …………………………………… 5.Abdomen covered with yellow pruinosity.St2-4 more or less with pale setulae.M ale with lateral epandrial lobe undeveloped ………6 Abdomen covered with grey pruinosity.St2-4 without pale setulae.M ale with lateral epandrial lobe developed ………………………10 6.Palpus black.Fr /fa ratio less than 0.20 ……………………………7 Palpus mainly or entirely yellow.Fr /fa ratio more than 0.41 ……8 7.Fr /fa ratio 0.20 ……………………D.spectabilis(Loew,1861) A Fr /fa ratio 0.05 ……………………D.spectabilis(Loew,1861) B 8.Fore coxa with only white setulae.Frons partly greenish with yellowish pollen ………………D.angustifrons(Robinson,1975) Fore coxa with black setae distally.Frons mostly obscured by gray pollen ………………………………………………………………9 9.Fore coxa and femur mostly yellow …D.wirthi(Robinson,1975) Fore coxa and femur mostly brown or greenish D.robustus(Robinson,1975) …………………… ………………………………… 10.5 dc.M id tibiae without pd ……………D.hongyaensis sp.nov.6 dc.M id tibiae with pd …………………………………………1111.Leg yellow,but cox2-3 brownish black,tarsomere 5 in each leg black.M id tibia with 1 ad ……………………D.frontus sp.nov.Leg black to brownish dark,tibiae yellow to brownish yellow,tarsomere 5 in each leg yellow to brownish yellow.M id tibiae withno ad …………………………………………………………………12 12.Claws vestigial.Pulvilii developed,almost as long as tarsomere 5 ………………………………………………D.succurtus sp.nov.Claws present.Pulvilii undeveloped ………D.curtus sp.nov.1 Dubius autumnalus sp.nov.(Figs 14,16) M ale.Body length about 2.4 mm;wing length about 2.2 mm.T he new species with face as narrow as frons,which is a unique feature in Dubius gen.nov.and may represent a new evolutionary direction in Dubius gen.nov.Holotype ♂,Longgong,Anshun,Guizhou(26°05’N,105°52’ E;alt.1 200 m),3 July 1994,W EI Lian-M eng.Etymology.From the Latin autumnal,meaning "autumn".2 Dubius curtus sp.nov.(Figs 11,17,26) M ale.Body length about 2.8 mm;wing length about 2.5 mm.T he new species closely related to D.succurtus sp.nov.,but can be separated from each other by the couplets in the key.Holotype ♂,Laogao Village,Duanqiao,Guanling,Guizhou(25° 53’ N,105° 38’ E;alt.600 m),20 Apr.2008.Paratypes:7 ♂♂,same locality as holotype,W EI Lian-M eng,CAO W eiPing,JIANG Shao-Gui and W ANG De-Xiang;5♂♂,Putunba,Bulang,Puding,Guizhou,alt.1500 m,26 Apr.2008,W EI Lian-M eng,CAO W eiPing and JIANG Shao-Gui;1♂,Langfengguan,Ziyun,Guizhou,alt.900 m,6 Apr.2008,W EI LianM eng,CAO W ei-Ping and JIANG Shao-Gui;1 ♂,Hongyabei,Duanqiao,Guanling,Guizhou,alt.900 m,12-13 Apr.2008,W EI Lian-M eng,CAO W ei-Ping,JIANG Shao-Gui,LIU M ei-Hua and XIAO Qian-Lin.Etymology.T he specific name is from the Latin word "curtus",meaning "curved".3 Chrysotus frontus sp.nov.(Figs 7,18,27) M ale.Body length about 2.2 mm;wing length about 2.3 mm.T he new species related to D.succurtussp.nov.and D.curtus sp.nov.,but these three new species can be separated from each other by the couplets 11 in the key.Holotype ♂,M aolan,Raolan,Guizhou(25°15’N,107°45’E;alt.600-650 m),19-20 June 2006,YANG Zai-Hua.Etymology.From the Latin "frons",meaning the new species with frons narrow.4 Dubius hongyaensis sp.nov.(Figs 10,19,26) M ale.Body length about 2.8 mm;wing length about 2.6 mm.Related to D.curtus sp.nov.,but can be separated from the latter by the couplets in the key.Holotype ♂,Hongyabei,Duanqiao,Guanling,Guizhou(25°56’N,105°39’E;alt.900 m),20 Apr.2008.Paratypes:3 ♂♂,same locality as holotype,W EI Lian-M eng,CAO W ei-Ping,JIANG Shao-Gui,W ANG De-Xiang and JIN W ei;1♂,W ula Village,Huangguoshu,Guizhou,alt.1 000 m,19-25 Apr.2008,W EI Lian-M eng,CAO W ei-Ping,JIANG Shao-Gui;1 ♂,Laogao Village,Duanqiao,Guanling,Guizhou,alt.600 m,18 Apr.2008,W EI Lian-M eng,CAO W ei-Ping,JIANG Shao-Gui.Etymology.T he specific name is from the the type locality-Hongya,Duanqiao,Guanling,Guizhou.5 Dubius succurtus sp.nov.(Figs 9,20) M ale.Body length about 3.3 mm;wing length about 3.0 mm.Related to D.curtus sp.nov.,but can be separated from each other by the couplets in the key.Holotype ♂,Gaopo,Jiangzhou,Duyun,Guizhou(26°11’N,107°20’E;alt.1500 m),Aug.to Sep.2011,W EI Lian-M eng,CAO W ei-Ping,SHOU T ian-Hong,JIN Peng and LONG Shu-W eng.Paratypes:2♂♂,same locality as holotype,June to July 2011,W EI Lian-M eng,W EI Lian-Jian,CAO W ei-Ping,LONG Biao,DU Kun,W ANG Qing-Da,LI Zhao-Quan and LUO M ing-Jian.Etymology.T he specific name is from the Latin word "curtus",meaning"curved",and"suc"meaning "to be close to",in reference to its similarity to D.curtus sp.nov.