Osteology of Bluegill Sunfish, Lepomis macrochirus Rafinesque

ブルーギルサンフィッシュの骨格に関する研究

Thakur Nirmal K.

Takahashi Masao

Murachi Shiro

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

The present study was undertaken in order to provide information upon the normal skeletal structure of bluegill sunfish, Lepomis macrochirus RAFINESQUE, to the researchers using it as an experimental animal and to the taxonomists trying to work out the relationship between the members of the Centrarchidae family.

This study is based upon the examination of 100 bluegill specimens made by cleaning, staining, and roentgnography. The observations can be summarized as follows:
i) Statistical analyses of various skeletal proportions revealed small fluctuations except for the cranium height and width which were observed to be size-dependent.
ii) Correlation between external and skeletal characters have been made to predict the position of several skeletal components on the body of fish without subjecting it to the troubles of scissors and forceps.
iii) Basic scheme of the arrangement of bones except for their shapes and sizes, has been found out to be more or less the same as that of Sacramento perch studied by DINEEN and STOKELY (1956). However, reduction in the number of certain skeletal components has been observed in bluegill.
iv) A second uroneural has been discovered in bluegill which hither-to had not been reported from any other centrarchid including bluegill.
v) Comparison of meristic measurements as stated by various authors presented some difference in the number of dorsal soft ray, trunk vertebrae, scales, and gill rakers.

Bluegill sunfish (Lepomis macrochirus RAFINESQOE)を実験動物として使用するために必要な基礎的知見を得,さらにその所属するクロマス科Centrarchidaeの魚類の分類に資する目的で,その骨格を精査した.

100尾の標本につき,常法,骨格染色法,X線写真により,骨の形状,配列,大きさ等を観察し次の結果を得た.
(1) 頭蓋骨の長さに対する高さ,巾の比率は魚の成長に伴って変化するが,他の骨格要素の大きさは,標準体長又は頭蓋骨長に比し略々一定の値を示し,魚の成長に伴い変化しない.
(2) 魚体の外形に対応して骨格の構成が一定している所から,数種の骨は位置を外形から容易に決定出来る.
(3) 骨の基本的配列は同科のSacramento perch (DINEEN and STOKELY,1956)と略々同様であるが,個々の骨の大きさ,形状は異なり,bluegill sunfishでは若干の骨が省略されている.
(4) bluegill sunfishを含むCentrarchidaeの魚の骨格について行なわれた従来の研究では,1ケしかないとされていた尾神終骨が2ケ存在することが確認される.
(5) 体節性構造の内,背鰭軟条,腹椎,鱗及び鰓耙の数が,従来得られていた結果と若干相違している.

Zoology [ 480 ]

eng

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563

[NAID] 40018463798