インドネシアシーラカンスLatimeria menadoensis初の幼魚の観察とLatimeria chalumnaeの胎仔との比較

抄録

The juvenile of Indonesian coelacanth, Latimeria menadoensis is here described for the first time in detail with comparison to embryos of Latimeria chalumnae. The juvenile was found in free swimming at 164.6 m depth off Manado, Indonesia on the 6th October in 2009. Because the total length of the juvenile is 31.5 cm, which is smaller than the embryos of L. chalumnae, it is speculated that not much time has passed from its birth. The depth at which the juvenile was found is within the range of the depth where adult L. menadoensis were observed, hidden in a narrow and long overhang where large predators could not enter. The juvenile has a more slender body, smaller orbit, shorter and deeper posterior part of the body (caudal peduncle) between the second dorsal and the anal fins and anterior ends of the dorsal and ventral lobes of the caudal fin (the third dorsal and second anal fins), longer dorsal and ventral lobes of the caudal fin (the third dorsal and second anal fins), broader peduncles of broader lobed fins, larger first dorsal fin and longer supplementary lobe of the caudal fin (caudal fin) than embryos of L. chalumnae. This indicates clear differences in the first ontogenetic stages of the two species, although adults have almost the same morphological features. Latimeria menadoensis appears to reproduce in a rather confined area, because both the juvenile and adults have been found within the same area inside of Manado Bay.