BULLETIN OF MARINE SCIENCE, 34(1): 21-59,1984 DESCRIPTION OF PORKFISH LARVAE (ANISOTREMUS VIRGINICUS, HAEMULIDAE) AND THEIR OSTEOLOGICAL DEVELOPMENT Thomas Potthoff, Sharon Kelley, Martin Moe and Forrest Young ABSTRACT Wild-caught adult porkfish (Anisotremus virginicus, Haemulidae) were spawned in the laboratory and their larvae reared. A series of 35 larvae 2.4 mm NL to 21.5 mm SL from 2 to 30 days old or older (larvae of unknown age) was studied for pigmentation characteristics. Cleared and stained specimens were examined for meristic and osteological development. Cartilaginous neural and haemal arches develop first anteriorly, at the center, and posteriorly, above and below the notochord, but ossification of the vertebral column is from anterior in a posterior direction. Epipleural rib pairs develop from bone, but pleural rib pairs develop from cartilage first and then ossify. The second dorsal, anal and caudal fins develop rays first and simultaneously, followed by first dorsal fin spine development. The pectoral and pelvic fins are the last of all fins to develop rays. All bones basic to a perciform pectoral girdle develop with cartilaginous radials present between the pectoral fin ray bases. Development and structure of pre dorsal bones and dorsal and anal fin pterygiophores were studied. All bones basic to a perciform caudal complex developed and no fusion of any of these bones was observed in the adults. Radial cartilages developed ventrad in the hypural complex. The hyoid arches originated from cartilage but the branchiostegal rays formed from bone. The development and anatomy of the branchial skeleton were studied. Spines develop on the four bones of the opercular series in larvae and juveniles but are absent in the adults. There are two species of Anisotremus in the north Atlantic Ocean: A. virginicus and A. surinamensis. In the north Pacific Ocean there is only one species A. davidsoni (Robins et a1., 1980). Recently, a third species A. moricandi has been redescribed for the north Atlantic Ocean by Acero p, and Garzon F. (1982), The larvae of the porkfish (Anisotremus virginicus) belonging to the percoid family of grunts (Haemulidae) have not been described previously, except by de Sylva (1970) who illustrated a 16.5 mm SL porkfish. Knowledge of the osteological development of A. virginicus is also lacking. The larvae of only two grunt species are described. Hildebrand and Cable (1930) described larvae of'the pigfish (Orthopristis chrysopterus) and Watson 1 (manu- script) is redescribing them. Saksena and Richards (1975) described laboratory- reared white grunt larvae (Haemulon plumien) with data on meristics and osteo- logical development. Courtenay (1961) described 13 species of juvenile grunts of the genus Haemulon from the western Atlantic. All aspects of the early life history of the porkfish are unknown. In this paper we describe the early life history stages including osteological development so that larvae caught in ichthyoplankton surveys can be distinguished from other similar- looking haemulid, sparid (Houde and Potthoff, 1976), or lutjanid larvae (Johnson, 1978). The detailed study of osteological development presented here may be useful in future studies of percoid relationships. I Marine Ecological Consultants of Southern California, 533 Stevens Avenue, Solana Beach, CA 92075. 21 22 BULLETIN OF MARINE SCIENCE, VOL. 34, NO. I, 1984 MATERIALS AND METHODS Porkfish larvae were spawned and reared by M. Moe and F. Young in the Aqualife Research Corporation laboratory in the Florida Keys. Thirty-five larvae from 2.4 mm NL to 21.5 mm SL were killed and preserved in 5% formalin' 2, 4, 8, 9, 15, 21 and 30 days after hatching; three of the largest reared larvae were of unknown age (Table I). In addition, five adult porkfish from 140 to 168 mm SL, caught in South Florida waters with a spear gun or hook and line during our study in 1981, were used in the study. Of the reared larvae, 26 were preserved for 3 years in 5% formalin and six were preserved for 2 years before our study began. For the largest three larvae the length of preservation was unknown. A. virginicus larvae were measured for notochord length (NL, prellexion and lIexion stage) or standard length (SL, postllexion stage). The methods of measurement and the preparation and treatment of larvae,juveniles and adults for and during the study are given in Potthoffet a!. (1980) in the Materials and Methods section. In clearing and staining we followed the methods of Taylor (1967) and Dingerkus and Uhler (1977), In the following text the reared larvae will be referred to by length; their ages can be obtained from Table I. For the caudal complex we use a composite terminology following Gosline (1961a; b), Nybelin (1963) and Monod (1968). For the terminology ofthe branchial and hyoid arches we follow McAllister (1968), Nelson (1969) and Rosen (l973). These terminologies have been previously used by Potthoff and Richards (1970), Potthoff(1974, 1975), Houde and Potthoff(1976), Fritzsche and Johnson (1980), Potthoff (1980), Potthoff et a!. (i 980), Johnson (1981) and Potthoff and Kelley (1982). Spawning and Rearing Adult porkfish, A. virginicus, were collected live on Coffins Patch reef off Marathon in the Florida Keys on 8 November 1978 and 4 November 1979 for experimental spawning. The fish were spawned on the evening of the day of capture. Most of the females were reproductively active and the eggs hydrated and ovulated naturally so hormone injections were unnecessary, The eggs were expressed manually shortly after ovulation into a small bowl and sperm from a male was immediately added. Salt water of the same salinity and temperature as the holding tank was added to the bowl and the eggs and salt water were stirred. Water temperature for spawning and rearing was 27° ± 2°C, The eggs were placed in the rearing tanks soon after first cleavage was observed. The fish were reared in 946-1 circular-polyethylene tanks with conical bottoms. Constant lighting was provided by two 122 cm, 40 watt daylight spectrum lIuorescent bulbs. Salinity was 350/00 throughout the rearing. For the destruction of protozoan fish parasites and the reduction of bacterial levels, treated natural sea water was used for the first 4 to 6 weeks of larval rearing. Water treatment consisted of an overnight application, about 14 h, of 4 to 6 ppm of free chlorine with subsequent dechlorination with sodium thiosulphate and filtration through sand and activated carbon before addition to the rearing tank. Water changes of about 50% of the volume of the rearing tank were made once a week. Larval foods during the first 3 weeks consisted of wild plankton, cultured rotifers, copepods and brine shrimp nauplii, Large brine shrimp, commercial tropical fish lIake foods finely ground and fine particles of shrimp lIesh were added to the diet as the fish became large enough to accept them. At 5 to 6 weeks of age the young porkfish were transferred to 1,361-1 grow-out tanks supplied with a constant lIow of filtered sea water. PIGMENTATION Two or 3 years elapsed between the time that larvae from the two spawnings were preserved in 5% formalin and subsequently examined. The preservation period did not affect pigmentation noticeably. Head Region. -All larvae 2.4-2.8 mm NL had unpigmented eyes. Of these, three out of five larvae lacked pigment in the head region and two had three to four stellate melanophores on the snout and forebrain as shown in Figure 1 for the 2.5 mm NL specimen. All A. virginicus 2.4-2.6 mm NL had stellate melanophores on the snout and forebrain. Two specimens had one to two melanophores on the 2 Use of any product used in this paper does nol imply endorsement by the National Marine Fisheries Service, NOAA. POTTHOFF ET AL.: ANISOTREMUS LARVAL DEVELOPMENT 23 Table 1. Fin spine and ray counts of 35 laboratory-reared Anisotremlls virginiclls larvae and 5 captured adults from the Florida Keys (specimens above dashed line have an unflexed notochord, those below the dashed line have a flexed notochord) Pelvic Caudal Fin Rays Pectoral Fin Dorsal Fin Anal Fin Fin Rays Rays Principal Secondary Cleared NL or Days After Spines and Spines (One (Upper/ (Upper/ Total and SL, mm Hatching Rays and Rays Right Left Side) Lower) Lower) Number Stained 2.4 4 0 0 0 0 0 0 0 0 No 2.4 4 0 0 0 0 0 0 0 0 No 2.5 4 0 0 0 0 0 0 0 0 No 2.5 4 0 0 0 0 0 0 0 0 No 2,6 4 0 0 0 0 0 0 0 0 No 2.7 2 0 0 0 0 0 0 0 0 No 2.7 2 0 0 0 0 0 0 0 0 No 2.7 2 0 0 0 0 0 0 0 0 No 2.8 2 0 0 0 0 0 0 0 0 No 3.2 9 0 0 0 0 0 0 0 0 No 3.4 9 0 0 0 0 0 0 0 0 No 3.5 9 0 0 0 0 0 0 0 0 Yes 3,7 9 0 0 0 0 0 0 0 0 Yes 3.8 9 0 0 0 0 0 0 0 0 Yes 3.9 8 0 0 0 0 0 0 0 0 Yes 4.3 8 0 0 0 0 0 0 0 0 Yes --------------------------------------------- 5.7 15 0,12 2,7 0 0 0 9/8 0/1 18 Yes 5,9 15 No 6.2 15 IV-2,16 1-1,10 0 0 0 9/8 1/1 19 Yes 6.4 15 V-3,16 I-I, I0 6 6 0 9/8 2/2 21 Yes 7.1 21 X-2,16 11-1,10 11 11 1,3 9/8 4/4 25 Yes 7.5 21 XI-l,16 11-1,10 15 15 1,4 9/8 5/5 27 Yes 8.2 21 X-2,17 11-1,10 16 16 1,5 9/8 6/6 29 Yes 8.6 30 XII,16 11-1,10 17 17 1,5 9/8 8/7 32 Yes 8.7 30 XII,16 11-1,10 16 16 1,5 9/8 7/7 31 Yes 8.8 21 XI-I,17 II-I,ll 15 1,5 9/8 7/7 31 Yes 9,0 30 XI-I,15 11-1,10 17 17 1,5 9/8 9/8 34 Yes 9,6 30 XI-I,17 11-1,10 17 16 1,5 9/8 9/9 35 Yes 9,6 30 XI-I,16 11-1,10 16 17 1,5 9/8 8/8 33 Yes 9.8 30 XI-1,I5 IT-I,IO 16 17 1,5 9/8 9/9 35 Yes 10.1 30 XI-I,16 II-I, II 17 16 1,5 9/8 9/8 34 Yes 10.4 30 XI-I,16 IT-I,IO 16 16 1,5 9/8 10/9 36 Yes 20,2 Unknown XII,16 III, 10 17 17 1,5 9/8 13/12 42 Yes 20.4 Unknown XII,15 11,11 17 16 1,5 9/8 13/12 42 Yes 21.5 Unknown XIII,16 III, 10 17 17 1,5 9/8 13/12 42 Yes 140 Not reared XIT,16 III, 10 17 17 1,5 9/8 11/12 40 Yes 158 Not reared XI,18 III, 10 18 18 1,5 9/8 13/12 42 Yes 159 Not reared XII,16 III, 1I 18 18 1,5 Yes 164 Not reared XII,16 III, 10 18 18 1,5 9/8 12/12 41 Yes 168 Not reared XII,16 1II,10 17 1,5 9/8 13/12 42 Yes midbrain.