Zoological Studies

Vol. 43 No. 4, 2004

Review of the Teleostean Adductor Mandibulae and Its Significance to the Systematic Positions of the Polymixiiformes, Lampridiformes, and Triacanthoidei

Kao-yi Wu* and Shih-chieh Shen

Department of Zoology, National Taiwan University, Taipei, Taiwan 106

Kao-yi Wu and Shih-chieh Shen (2004) Divisions of the adductor mandibulae among a wide spectrum of teleostei were surveyed. Feeding habits do not generally dominate the number or nature of divisions of the adductor mandibulae. This muscle is innervated by the ramus mandibularis V, which is a reliable character for identifying divisions, which were redefined on this basis. Section A2β of the adductor mandibulae inserts into the Meckelian fossa, and connects with section Aw. The ramus mandibularis V always lies lateral to section A2β, and enters the Meckelian fossa together with it. Sections named A1β vary among teleosteans and are not always homologous. In the Clupeomorpha, Cyprinidae, Mugilomorpha, Atherinomorpha, and Percomorpha, the adductor mandibulae shows consistent and stable subdivisions. Divisions of the adductor mandibulae also support the Mugilomorpha and Atherinomorpha being sister groups. An A1+A2α division is found in the Percomorpha, Lampridiformes, and Polymixiiformes. Another particular configuration of A1 and A2α is found in the Triacanthoidei and Percoidei. The synapomorphic characters in the past literature for supporting Acanthomorpha and Percomorpha were revised, and these show large amounts of homoplasy.

Key words: Teleostei, Adductor Mandibulae, Systematics, Percomorpha, Triacanthoidei.