EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



127 



Fig. 1 Type epaxial muscle as exemplified by Morone chrysops (MPM 4569, 78.8 mm SL). Inclinatores dorsales removed to expose medial 

 muscles. Note that there is no insertion of the epaxial musculature to the distal tips of the pterygiophores. Margins of muscle demarcated by 

 thicker lines; bone stippled. DD, depressores dorsales; DI, distal radial; ED, erectores dorsales; EPAX, epaxialis; PM, proximal-middle 

 radial; SCA, supracarinalis anterior; SCP, supracarinalis posterior; SN, supraneural; SP, spines; SR, segmented ray. Scale bar = 10 mm. 



EPAX 



Fig. 2 Type 1 epaxial muscle as exemplified by Epinephelus merra (USNM 246689, 96.5 mm SL). Inclinatores dorsales removed to expose 

 medial muscles. Note the separate slip of epaxial muscle which inserts dorsally on to the second pterygiophore (directly behind the second 

 spine) and the additional insertions on to pterygiophores 3-8. Abbreviations and other methods of presentation as in Fig. 1. Scale bar = 5 

 mm. 



Among these apomorphic morphologies. Type 1 is the 

 easiest to characterize and identify. It is found among a 

 restricted group of perciform families and is considered the 

 exclusive epaxial/pterygiophore association of the Scorpaeni- 

 formes (see below for discussion of Type condition in 

 Bathylutichthys). A scorpaeniform sister group has remained 

 elusive and this has been a serious barrier to understanding 

 internal relationships of the Scorpaeniformes. The presence 

 of a derived Type 1 epaxial morphology in the Scorpaeni- 

 formes and a small subset of the Perciformes suggests that the 

 sister group of the Scorpaeniformes possibly lies within this 

 subset. Percoid taxa rarely have been considered candidates 

 for such status, although seven percoid families exhibit a 

 Type 1 morphology (Table 1; Figs 2, 4-5). Despite generally 

 being recognized as a heterogeneous and probably non- 

 monophyletic assemblage (e.g. Johnson, 1984), percoids 

 have been referred to as a single, identifiable taxonomic 



SP1 



PM SR1 V 



Fig. 3 Type 1 epaxial musculature in the batrachoidid Opsanus 

 beta (MPM 8919, 139.5 mm SL). Insertions to the 11th dorsal-fin 

 pterygiophore. SP1, first spine; SRI, first segmented ray; other 

 abbreviations and methods of presentation as in Fig. 1. Scale bar 

 = 10 mm. 



Fig. 4 Type 1 epaxial musculature in three percoids: a, Apogon 

 maculatus (MPM 24869, 64.6 mm SL), Apogonidae, with 

 insertions to the first through third pterygiophores; b, 

 Centrogenys vaigiensis (USNM 150792, 53.4 mm SL), 

 Centrogeniidae, with insertions to the first through seventh 

 pterygiophores; c, Perca flavescens (MPM 25409, 79.2 mm SL), 

 Percidae, with insertions to the fourth through ninth 

 pterygiophores. Abbreviations and other methods of presentation 

 as in Figs 1,3. Scale bars = 5 mm. 



