Larval Development in the Lutjanid Subfamily Etelinae (Pisces): The Genera Aphareus, Aprion, Etelis and Pristipomoides
Abstract:Larval development in the lutjanid subfamily Etelinae is described and illustrated from field specimens captured with plankton nets and midwater trawls in the Atlantic, Indian and Pacific Oceans. Series were assembled using fin-spine morphology, scale counts, gill-raker counts, and pigment patterns. Identifications were confirmed from adult characters developed in the largest specimens and from the distributions of the adults. Larvae of the Etelinae share with larvae of other lutjanids the presence of a spine on the dorsal postcleithrum, early forming, very elongate spines of dorsal and pelvic fins, and even longer pelvic-fin soft rays. They are further characterized by fin-ray counts (D X, 10; A III,8), absence of external ornamentation on fin spines (except Aprion where weak, trailing-edge serrations are present), early forming pigment on the midbrain posteriorly, and early formation of both third anal-fin spine and scales. Aprion virescens is characterized by serrate fin spines, an especially long second spine in the dorsal fin, pigment series on the longest dorsal-fin spines, pigment on the urostyle and absence of dorsal pigment on trunk and tail. A. virescens is pelagic until at least 18 mm. Etelis spp. are characterized by a long, fragile second spine in the dorsal fin, fin spines lacking internal structure, pigment series on the pelvic-fin spine and longest dorsal-fin spines, absence of dorsal pigment on trunk and tail, ventral limited pigment on tail that disappears early, pigment on the forebrain that forms early, and absence of urostyle pigment. We lacked specimens between 8.6 and 13.7 mm. Three Indo-Pacific types of Etelis larvae unidentified to species and distinguished by minor pigment and preopercular spine differences are recognized in specimens <8.6 mm. Specimens >13.7 mm are identified as E. carbunculus, E. coruscans (Indo-Pacific) and E. oculatus (Atlantic), primarily on the basis of counts of scales and gill rakers and of geographical distributions. Etelis spp. are pelagic to at least 51 mm. Aphareus and Pristipomoides larvae are virtually indistinguishable and are characterized by a moderate-sized second spine in the dorsal fin (often shorter than pelvic-fin spine), fin spines with distinctive internal structure, a pigment cluster at the base of both anal fin and dorsal fin posteriorly, urostyle pigment at some period during development and lack of pigment series on the dorsal-fin spines. The Indo-Pacific A. rutilans, P. auricilla, P. filamentosus, P. multidens and/or typus, P. sieboldii, and two unidentified members of Aphareus or Pristipomoides (with incomplete series) and the Atlantic P. aquilonaris and what is possibly P. freemani are differentiated by lengths of dorsal-fin spines, minor differences in pigmentation, numbers of lateral-line scales and gill rakers, and geographical distribution. Aphareus rutilans also has a shorter ascending process of the premaxilla than do the Pristipomoides spp. Aphareus and Pristipomoides spp. are pelagic to at least 54 mm. Two types of larvae from the western Pacific with incomplete series (maximum size, 5.7 mm) of a total of five specimens cannot be identified to genus (they are not Randallichthys). They are characterized by deep bodies, relatively short dorsal fin spines, fin spines that lack ornamentation or internal structure, very light pigment and small size at flexion. The putative species are questionably separated by minor pigment differences, size at flexion, body depth, and fin-spine length. Evidence from larvae supports the distinctiveness of Etelis and Aprion and indicates that Aphareus and Pristipomoides are very closely related. The unidentified larvae from the western Pacific are important, for if they prove to be P. argyrogrammicus and/or P. zonatus, they will indicate that these two species are probably not closely related to the other species of Pristipomoides.
Document Type: Research Article
Publication date: 1994-07-01
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