Species divers. 17(2): 161-167 (2012)

Species Diversity 17: 161–167
25 November 2012
Morphology and Function of Pectoral Fin Muscles in
Lizardfishes (Actinopterygii: Aulopiformes: Synodontidae),
with Comments on an Additional Muscle of the Fin
Monruedee Chaiyapo1,3, Hisashi Imamura2 and Mamoru Yabe2 1 Chair of Marine Biology and Biodiversity (Systematic Ichthyology), Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan E-mail: m.chaiyapo@fish.hokudai.ac.jp 2 Laboratory of Marine Biology and Biodiversity (Systematic Ichthyology), Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan E-mail: imamura@fish.hokudai.ac.jp (HI); myabe@fish.hokudai.ac.jp (MY) (Received 6 September 2012; Accepted 16 November 2012) The morphology of the pectoral fin muscles of lizardfishes (Synodontidae) is described. Members of this family com- monly have six pectoral fin muscles: the abductor superficialis, abductor profundus, arrector ventralis, adductor superfi- cialis, adductor profundus, and arrector dorsalis. An additional muscle, the arrector medialis (named in this study), was discovered on the mesial side of the pectoral fin in all nine examined species of Synodus and Trachinocephalus, but is absent in all four examined species of Harpadon and Saurida. It inserts on an anterior process of the base of the mesial half of the uppermost ray and appears to have a function similar to that of the arrector ventralis in supporting the protraction of the uppermost ray and the abduction of the pectoral fin. This muscle supports the division of the synodontids into two groups (present in Synodus and Trachinocephalus vs absent in Harpadon and Saurida). The function of the arrector medialis is morphological y discussed.
Key Words: lizardfishes, Synodontidae, pectoral fin, muscles, arrector medialis.
Synodontidae has not otherwise been studied in detail. In Introduction
this study, the pectoral fin muscles of representatives of this family were re-examined, and a unique muscular bundle The family Synodontidae, a member of the order Aulopi- was found that has never before been reported in fishes.
formes, comprises four genera and about 57 species (Nel- son 2006). Species are commonly found on coral, rock, and sand bottoms in shallow coastal waters of temperate and Materials and Methods
tropical regions in the Atlantic, Indian, and Pacific Oceans (Russell 1999; Nelson 2006). The purposes of this study are Preserved specimens were stained with alcian blue and to describe the pectoral fin muscles of the Synodontidae, to alizarin red-S before dissection. Dissections and observa- discuss their functions, and to review available comparative tions were undertaken with a Leica stereomicroscope fitted data. Although anatomical studies of the Aulopiformes, es- with a camera lucida attachment to facilitate il ustrations. pecial y the family Synodontidae, have been conducted by Osteological and myological terminology follows Sato and several authors (Rosen 1973; Sulak 1977; Baldwin and John- Nakabo (2002) and Winterbottom (1974) respectively. Spec- son 1996; Sato and Nakabo 2002), they have mostly focused imen sizes are reported as standard length (SL). Institutional on osteology and few authors have studied the myology of abbreviations follow Eschmeyer (1998), except for the Hok- the order. Rosen (1973) examined the interrelationships kaido University Museum, Hakodate (HUMZ).
among higher euteleostean fishes focusing on characters of Material examined. Synodontidae: Harpadon nehereus
the pharynx, jaw, and caudal regions. With regard to au- (Hamilton, 1822), HUMZ 201983, 162 mm SL; Harpadon lopiform myology, he described the pharyngobranchial squamosus (Alcock, 1891), MCZ 149098, 103 mm SL; Sau- and cheek muscles and made some use of these characters rida nebulosa Valenciennes, 1850, HUMZ 124908, 107 mm in inferring relationships among euteleostean orders. Sato SL; Saurida tumbil (Bloch, 1795), USNM 404394, 181 mm and Nakabo (2002) examined the pectoral fin muscles of SL; Synodus evermanni Jordan and Bollman, 1890, AMNH many aulopiforms, including the four synodontid genera, 234786, 106 mm SL; Synodus foetens (Linnaeus, 1766), and used two transformation series including characters AMNH 80195, 131 mm SL; Synodus hoshinonis Tanaka, associated with the adductor profundus, an element of the 1917, HUMZ 114357, 198 mm SL; Synodus lucioceps (Ayres, pectoral fin muscles, to infer phylogenetic relationships 1855), HUMZ 113029, 162 mm SL; Synodus sageneus within this order. Until recently, the myology of the family Waite, 1905, AMS I.22831-040, 141 mm SL; Synodus saurus 2012 The Japanese Society of Systematic Zoology

Source: http://jssz.sakura.ne.jp/spdiv/v17/abs/sd170206.pdf