黄鳝的地理分布及起源的探讨

<正> 一、黄鳝Monopterus albus(zuiew)的地理分布黄鳝同黄蝉、黄(鱼旦)。又简名鳝鱼或(鱼单)鱼。山、陕亦名蛇鱼。两千多年前的山海经内就有“灌河之水其中多(鱼旦)”的记载。是我国人民习见和喜食的淡水鱼类之一。但迄今其地理分布尚无专文研究。不少文献称黄鳝分布于我国各处,或称除西北、西南外我国各处均产;但事实远非如此。据笔者研究在我国仅见于辽河下游;沿滦河向上约略过承德(海拔

DISCUSSION ON THE GEOGRAPHIC AI DISTRIBUTION AND ORIGIN OF THE RICE—FIELD EEL(MONOPTERUS ALBUS)

The rice—field eel(Monopterus albus)is a very common edible freshwaterfish in China.Its geographical distribution and origin still haven't been speciallydiscussed in ichthyological bibliography before.Thia paper is an attempt to solvethis problem.Based on many ichthyologists' works;the natural habitat area ofthis eel is known merely located in the southeatern part in China from sea le-vel to 2926m(fig.1).The height above sea level of the uppermost limit line islower in the north and higher in the south.For example,it is about 534.7m atLuan—ping County along the Luan River,1090m at Wu—du County along theJialing R.,2926m at Yanyuan Plain along the Ya—long R.,2446m at LashihaiLake,Jianyuan County,along the Lanchang R.These are determined by the te-mperature of water,because this eel is a warm freshwater fish,requiring 25-30 ℃ during its spawn season.In the valleys among the Hongduan Mountains,this line is much higher,because the se areas are still influenced by the south-warm—damp—air current after they were remarkably elevated by the HimalayasNew Crustal Movements during Quaternary Period.This eel doesn't occurabove Longmen to Hukou Waterfall along the Yellow River,since the wate-rfall is too high for this eel to swim upriver.This eel living in Hami,Xinji-aug Uygur Autonomous Region,is descendant of that inplanted by Zuo Zhong-tang's Army about in 1875.This eel also occurs in the southeastern part of Korea,Kyoto to Byukyuin Japan,Luzon Island,Burma,Vietnam,Iaos,Cambodia,Thailand,Malay-sia,Borneo,Sumatra &Java;from sea level to 915m(Herre,1953).It ismainly a tropical-coastal-freshwater fish in southeast Asia.This fish belongs to Synbranchiformes.Fishes of this order are eel-sha-ped;no airbldder,ribs,orbitosphenoid,suborbitals,scapula,coracoid,rad-ials of pectoral fin,and fin spines;dorsal and anal confluent with the sm-all caudal,no fin rays;including 2 suborders;3 faimiles,7 genera and about12 species.Alabetoidei consits Alabetidae,Alabes and 4 species;scaleless;jugular pelvic fin with 2 rays;anus in anterior half of body and pareitals se-parated by supraoccipital;occurring in Australia coastal seas(includ.Tasman-ia).Synbranchoidei:dorsal and anal fins like a ridge,no pelvic fin,anus in hindhalf of body and pareitals connected;2 families,5 genera and about 8 speci-es.Amphipnoidae has only 1 species(Amphipnous cuchia),body scaled,2 lunglike air-sacs connecting with gill cavity;living in fresh-and brackishwaters from India to Burma and Queensland.Synbranchidae:without lungli-ke airsacs and scales.Macrotrema caligans:large gill openings attainingup to body side and occurs in seas of Singapore to Java and Thailand,andis able to enter in river at Bangkok.Blind cave species are known from Yu-catang,Mexico(Furmastix infernalis)and Liberia(Typhlosynbranchus bou-eti).Burrowing nocturnal eels are known(Sgnbranchus bengalensis)fromIndia to Philippines,NewGuinea and islands off the coast of W.Australia;S.afer from Guinea and Lower Nigeria;and S.marmoratus from Mexico toArgentina and some of the Antillean islands.Monopterus albus has been de-scribed above.Therefore,fishes of this order are mainly living in tropical-coastal sea-and freshwaters of Asia,W.Africa and Americas.Their first an-cestors might be appeared in late Cretaceus Period(fig.2),afterwards dist-ributed from southeastern Asia to the east coast of N.America and W.Africaalong the north coast of the Tethys Sea.If later,they would not be ableto cross the wide-deep Atlantic Ocean.In Miocene,some of them distributedfrom Taiwan to Luzon,Philippines,and from Southeastern A sia to Austr-alia(fig.3).Based on many papers,Synbranchiformes seems more specialized thanAnguilliformes(with physostomous airbladder etc.)and more primitive thanPerciformes(pareitals separated or disappeared etc.)In Sybranchiformes,Albetoidei is more specialized than Synbrachoidei;Amphipnoidae is more pr-imitive than Synbranchidae;Macrotrema is the most primitivt and Monopterus(protogynous hermaphrodite,gills 3)the most advanced among Synbranchidae