Morphological and identification of fish larvae (Acanthuridae, Gempylidae and Trichiuridae )

from Southeast Asia waters

by

Kosum polrong

Review to morphological features

AcanthuridaeBody shape : Pre flexion-body is moderate deep, strongly compressed laterally, they have 21-23 myomeres and the gut coiled.

Flexion-deeper more than of body, snout have a triangular

head and the mouth is small. The eyes a round and moderate to large size.

Spination :

Pre flexion-the smaller spines is early appearance in larvae 1.8 mm have a bones such as supraoccipital crest serrate, preopercle, lower jaw, mid-ventral keel and pelvic girdle.

Flexion-following presented of spines at the supracleithral, posttemporal, opercular serrate

Pigmentation

Preflexion-The larvae pigment present on brain, gut, along throat, lower jaw, and dorsal surface of gas bladder. Flexion-In some species. The pigment occurrence on caudal peduncle and increase to heavy and density in late stage.

Similar families and genus

Difference of characters

- Zanclids not have large anal fin spine, the elongate of third dorsal fin spine and in preflxion stage have a longer than of preanal length.

- Menids lack elongate fin spine and serrate crests or ridges of head.

- siganids and leiogngsthids have larger than preopercular spines and sometime of myomeres number more than to 24

Table 1 Meristic characters larval of Acanthuridae (Ahlstrom, 1948; Leis and carson,2000;Richards, 2006; Chayakul, 2007)

a = present studyB = from review

Size(mm) D A P1 P2 C M

- (b) IV-XI, 19-33

II-III, 18-32

14-19

I, 3-5

8+8 21-23

5.30 (a) V, 29 II, 30 16 I, 0 8+8 22

Specimens data

Participant : Mr. Pitoon puewkhao

Family : Acanthuridae

Generic name : Naso sp.

Sampling locality : Andaman sea

Sampling gear : Bongo net

Stage: Flexion

Measurements of data

- Body length(BL) = 5.30 mm.

- Head length(HL) = 2.20 mm.

- Eye diameter(ED) = 0.50 mm.

- Snout length(SnL) = 1.20 mm.

- Preanal length(PAL) = 1.93 mm.

- Body depth(BD) = 4.20 mm.

Figure A. Naso sp.2.20 mm.(Leis and carson, 2000)

Figure B. Naso sp.3.80 mm.(Leis and carson, 2000)

Figure 1 Naso sp.

5.3mm.(BL) 40 x

Morphological features

Body shape :

- Very deep(79.26%) - Large head(41.51%)

- Small eye(22.73%)

Gut :

- Coiled

Head spination

- Supraocipital crests and spraocular

Pigmentation

The pigment present on brain, around of abdominal cavity, pectoral fin base and caudal peduncle. All pigment increase to heavy and density in late stage.