低等真骨鱼类肌间骨的比较分析

Comparative analysis of intermuscular bones in lower teleosts

对骨舌鱼总目、海鲢总目、鲱形总目和骨鳔总目等低等真骨鱼类肌间骨的数量、形态和分布进行了比较分析，结果如下：1．海鳗肌间骨的数目最多（409枚），其次是刀鲚（221枚），黄颡鱼肌间骨数最少（8枚），双须骨舌鱼次之（70枚），鲤科鱼类的肌间骨数目在99～133之间。2．从骨舌鱼总目到骨鳔总目，各种肌间骨可归纳为7种形态类型，从简单形态向复杂形态演化，然后出现退化现象。双须骨舌鱼只有形态最简单的“I”形髓弓小骨，没有脉弓小骨；海鲢总目的海鳗出现一端两分叉的形态，而鲱形总目的鲥和刀鲚出现一端多分叉的形态，到骨鳔总目的各种鱼类，开始出现两端两分叉，并在此基础上出现各种更复杂的形态；肌间骨形态在鲤科的鲒亚科最复杂，从雅罗鱼亚科开始退化，到鲇形目髓弓小骨完全消失，而脉弓小骨仅留少数简单的I形；脉弓小骨形态的复杂性要比髓弓小骨低。3．从前向后，髓弓小骨形态依照从复杂到简单的顺序排列，而脉弓小骨没有这种明显的排列顺序。根据低等真骨鱼类的系统发育关系，结合肌间骨形态及其在各肌间隔的分布规律，本文认为，目前鲤科鱼类的各种肌间骨是通过两个途径演化而来的：从“I”形-“卜”形-“Y”形-一端多叉形和从“I”形-“卜”形-“Y”形-两端两分叉形-两端多叉形-树枝形。

The comparative analysis on number, morphology, and distribution of intermuscular bones in lower teleosts nonacanthomorph such as Osteoglossomorpha, Elopomorpha, Clupeomorpha, Ostariophysi, was conducted. Pike eels （Muraenesox cinereus ）, estuarine tapertail anchovies （Coilia ectenes ） yellow catfish （Pelteobagrus fulvidraco ） and arowanas （Osteoglossum bicirrhosum ） owned 409, 221, 70 and 8 intermuscular bones, respectively. on the range from 99 to 133. The The numbers of intermuscular bones morphology of intermuscular bones in the fishes of Cyprinidae fell down here was classified into seven tvpes based on the bone complexity. From Osteoglossomorpha to Ostariophysi, the bones were evolved from simple type to various complexity types, then, retrogressed to simple types. Arowanas only owned simplest ＂I＂-type epineurals, another type one-end-bifork epineurals was found in pike eel, meanwhile several simple-type epipleurals appeared. In herrings （ Tenualosa reevesii） and estuarine tapertall anchovies （ Coilia ectenes）, a little more complexity epineurals like one-end-mulfifork type were found. As to Xenocypridini and Cyprinidae, most complexity type tree type was evolved. From Leuciscini, the epineurals initially retrogressed to a little simple type, finally to Siluriformes, the epineurals totally was disappeared, and the epipleurals also retrogressed to most simple type. Comparing with epineurals, the epipleurals emerged a little later, and formed a litter simpler. The complexity degree of various epineurals with rostrocaudal arrangment decreased gradually. However, the decreasing trend of the complexity degree of epipleurals was not evident. On the whole, Consideration taken together with lower teleostean phyologenetic relation, the morphology and arrangement of intermuscular bones, two paths of intermuscular bone evolution in Cyprinidae were postulated. One is from ＂I＂ type （no-fork type） to ＂ 卜＂ type （one-end-unequal-bifork type）, then to ＂Y＂ type （one-end-equal-bifork type）, finally to one-end-mutifork type, another is from ＂I＂ type to ＂ 卜＂ type, then to ＂Y＂ type, then to two-end-bifork type, then to two-end-mutifork type, finally to tree type. The research results provided here will help us to understand the evolution of intermuscular bones.