Relationships between spot type on male anal fin of Malawian mouth-brooding cichlid fishes and mating behavior

8種の口内保育型マラウイ湾産シクリッドについて、繁殖行動を観察し、雄臀鰭の斑紋タイプと繁殖行動との関係を調べた。繁殖行動は7つの段階、すなわち、体側誇示(段階1)、誘導(段階2)、刺激(段階3)、産卵(段階4)、卵回収(段階5)、受精(段階6)、擬似受精(段階7)、に区分された。臀鰭の斑紋は4タイプ、すなわち、卵型(Labidochiromix caeruleus、Melanochromis auratus および Pseudotropheus zebra)、長卵型(Aulonocara hansbaenschi)、楕円型(Nimbochromis livingstoni)および消失型(Aulonocara jacobfreibergi、Fossorochromis rostratus および Placidochromis electra)に分けられた。段階1と3は全種で観察され、段階7は、A. hansbaenschi と F. rostratus 以外で観察された。段階4から6は P. electra と N. livingstoni でのみ観察された。一方、段階2は卵型あるいは長卵型斑紋を有する A. hansbaenschi、L. caeruleus および M. auratus でのみ観察され、雌の繁殖行動誘発における卵型の斑紋の役割が示唆された。

Mating behavior was observed on 8 mouth-brooding Malawian cichlid species in aquarium, and was discussed from a viewpoint of the spot type on the male anal fin. The mating behavior for the pair was divided into seven steps; step 1, display; step 2, navigation; step 3, stimulation; step 4, oviposition; step 5, egg collection; step 6, fertilization; and step 7, mimic fertilization. Spots on the anal fin were categorized into four types; oval (Labidochromis caeruleus, Melanochromis auratus and Pseudatrophaus zebra), narrow-oval (Aulonocara hansbaenschi), ellipsoidal (Nimbochromis livingstoni) and disappeared (Aulonocara jacobfreibergi, Fossorochromis rostralus and Ptacidochromis electra). Steps 1 and 3 was observed for all the species. Step 7 was observed for all the species except for A. hansbaenschi and F. rostratus. Steps 4 to 6 were observed only for N. livingstoni and P. electra. On the other hand, step 2 was observed only for A. hansbaenschi, L. caeruleus and M. auratus, belonging to oval to narrow-oval spot types, suggesting the role of oval-type spots in induction of mating behavior of females.