DESCRIPTION OF EGGS AND EARLY LARVAL STAGES OF COMMON SARDINE (STRANGOMERA BENTINCKI) AND MENHADEN (ETHMIDIUM MACULATUM)

Abstract

Eggs and yolk sac larvae of the Chilean common sardine, Strangomera bentincki, and menhaden, Ethmidium maculatum,
from laboratory cultured series, are described. Eggs of both species are typically planktonic and similar in morphology, with segmented yolk, with no oil globules. and reduced perivitelline space. The main distinctivecharacter between them issize. Eggdiameter ranges from 1.25 to 1.40 mm in E. maculatum (n = 47; average 1.30 mm), and from 0,89 to 1.03 mm in S. bentincki (n = 96; average 0.96 mm). In S. bentincki, length at hatching may reach from 2.5 to 3.2 mm NL (notochord length), and yolk is exhausted when 5.1 to 5.3 mm NL. At hatching, lengths of E. maculatum yolk sac larvae range from 3.7 to 3.9 mm NL. Yolk absorption is completed at 6.4 to 6.5 mm NL. Size of yolk sac and number of prcanal myomeres showed to be useful characters in separating early larval stages of both species. Sume other characters. regarding criteria for separation from other clupeiform larvae inhabiting the same geographic range. are given. Support for the new taxonomic position ofS. bentincki, early known as Clupea bentincki is provided here.  Because of the presence of smali and pelagic eggs, instead of relatively big and demersal ones, as observed in Clupea species from the northern hemisphere.