LARVAL DEVELOPMENT IN THE LUTJANID SUBFAMILY APSILINAE (PISCES) - THEGENUS PARACAESIO

Larval development in the lutjanid subfamily Apsilinae is described an d illustrated from specimens captured with plankton nets and midwater trawls in the Indian and Pacific Oceans. Series were assembled using b ody shape, fin-spine morphology, head spination, scale formation and c ounts, gill-raker counts, and pigment patterns. Identifications (mostl y to the genus level) were confirmed from adult characters developed i n the largest specimens and from the distributions of the adults. Larv ae of the Apsilinae share with larvae of other lutjanids the presence of a spine on the dorsal postcleithrum, early forming, very elongate s pines of dorsal and pelvic fms, and even longer pelvic-fin soft rays. They are further characterized by fin-ray counts (D X, 10; A III,8), a bsence of external ornamentation on fin spines, early forming pigment on the midbrain posteriorly, and early formation of the third anal-fin spine and scales. Of the three Indo-Pacific apsiline genera, Lipochei lus, Paracaesio, and Parapristipomoides, we were able to identify only larvae of Paracaesio. However, within this nominal genus are two dist inct larval morphologies (morphs), each with several larval types appa rently corresponding to species. Due to incomplete understanding of ad ult taxonomy and distribution in Paracaesio, it was not possible to id entify any of the larval types to species. Paracaesio larvae with abou t 70 lateral-line scales, a relatively slender body and very long, whi p-libe dorsal-fin spine 2 (to 96% body length) and equally long pelvic -fin ray 1 (to 370% P-2 spine length), scales that formed between 8 an d 11 mm, prominent pigment on the urostyle, and no melanophore at the cleithral symphysis are called Paracaesio morph-hi. These were identif ied as Paracaesio because, among apsilines, only this genus contains s pecies with about 70 lateral-line scales. Five types of Paracaesio mor ph-hi larvae, distinguished primarily by pigment patterns and secondar ily by minor differences in head spination, are described from larvae as large as 24 mm. For one larval type, apparently of the Paracaesio m orph-hi group, the largest specimen (6.2 mm) was too small to have sca les. Therefore, we could not establish that it was a Paracaesio specie s. We describe this very lightly pigmented larval type under the name Unidentified Apsilinae. Its South Pacific distribution nearly matches that of Parapristipomoides squamimaxillaris, so the possibility remain s it is that species. Larvae considered to be Paracaesio because they have about 50 lateral-line scales, but too many gill-rakers to be Lipo cheilus carnolabrum, are called Paracaesio morph-lo. These larvae have a relatively deep body, relatively short, robust dorsal-fin spine 2 ( to 31% body length) and pelvic-fin ray 1 (to 125% P-2 spine length), s cales that form between 7 and 9 mm, a melanophore at the cleithral sym physis until 4-7 mm, and no pigment on the urostyle. Three types of la rvae of this morph are described from larvae as large as 29 mm, and ar e distinguished by spination on supraorbital ridge, and lachrymal, and minor pigment characters. In one type, the largest larva was too smal l for us to be sun it had the adult complement of gill-rakers, and the re is a possibility it is L. carnolabrum um rather than a Paracaesio s pecies. Another type was identified as either Paracaesio gonzalesi or P. kusakarii based on scalation and pigment. The presence of two, dist inct morphs of Paracaesio larvae supports a suggestion made by W.D. An derson, Jr., based on adult characteristics, that there are two monoph yletic lines within this nominal genus. However, with the possible exc eption of one pigment character, larvae seem to provide no evidence th at Paracaesio is monophyletic.