(Linnaeus)
1. Distinctive characteristics of early developmental stages
(a) Eggs and larvae
Not recorded from the mangroves.
(b) Early juveniles (Based on 13 mm T.L. specimens)
Drepane punctata 1
The head and body are deep and laterally compressed. The body is darkly pigmented and not silvery, has no vertical bars and no pigmented spots. Cirri on the lower jaw is not discernible at this stage. The slope between the snout and the dorsal fin origin is gradual (the slope is very steep in juveniles and adults). The dorsal profile just above the eye is not raised at this stage (the inter-orbital region is strongly raised in fully grown specimens). A procumbent spine in the dorsal is absent at this stage. The pectoral fin is long, pointed, falcate, and its tip reaches up to the middle of the soft dorsal (the pectoral tip reaches up to the caudal base in fully grown specimens).
(c) Juveniles (Based on 50 mm to 170 mm specimens)
Drepane punctata 2
Drepane punctata 3
Juveniles of 50 mm in size have a laterally compressed silvery body with 4-8 light brownish-black vertical bands. The soft dorsal fin has no pigmented spots (which appear as the fish grow). A procumbent spine is still not discernible. The lower jaw possesses small cirri vertically (4-6 in number) at this stage. The inter-orbital region is not raised (for further taxonomic details vide section salient taxonomic characteristics below).
As the specimens grow to over 150 mm in length, the vertical bars are replaced by vertical rows of spots. The fringe of the cirri also start disappearing. The pectoral fin tip reaches the caudal peduncle and pigmented spots start extending up to the soft dorsal as the specimens grow bigger. The procumbent spine is still embedded in the body and becomes clearly visible as the specimens grow older. The fourth spine of the first dorsal is the longest. The inter-orbital is slightly raised at this stage.
2. Salient taxonomic characteristics
The presence of vertical bars on the body is reported to be the characteristic feature of Drepane longimanna. In the present study, juveniles of Drepane punctata possessing vertical bars were collected from the Southeast Indian mangrove waters. D. longimanna has not yet been reported from the Southeast Indian coastal region. Moreover, early juveniles and juveniles of Drepane punctata alone occur in the mangroves, while adults of up to 465 mm T.L. occur in the adjacent coastal waters and coastal reefs.
When tracing the life-history from a 13 mm size to 465 mm size, the pigmentation pattern showed interesting changes. The early juveniles (first stage) possess no vertical bars and no rows of spots. The body is not silvery in appearance but darkly pigmented. The juveniles (2nd stage) are silvery with 4-8 vertical bars in 40-110 mm size groups. When the fish attain over 150 mm in size (up to 465 mm), pigmented spots appear in vertical rows (3rd stage), replacing the bars (encountered in the 2nd stage).
In the absence of a detailed description about the adult D. longimanna in the literature, it would appear that the juveniles of D. punctata with vertical bars might have been misidentified as D. longimanna. However, the authors leave the matter to the taxonomists in the field concerned to decide on the validity of D. longimanna and are pleased to record here the juvenile characteristics of D. punctata which strongly duplicate or imitate the characteristics attributed to D. longimanna in the literature. The present description further endorses the outlined observations made by certain earlier works (vide Munro, 1955 for further details).
3. Salient biological characteristics
This species is reported to feed on bottom living invertebrates and fishes (Fischer and Whitehead, 1974). In the mangrove waters of the Southeast Indian region, the juveniles feed on benthic organisms such as gammarids, juvenile shrimps and benthic copepods (Jeyaseelan, 1981). Based on the early juvenile and juvenile recruitment in the mangroves of Southeast India, this species seems to breed throughout the year except May-July, with year to year variations in the breeding season however.
4. Salient ecological information
The adult of the species occurs in coastal, coral and rocky reefs, while the early juveniles and juveniles use the mangroves as a nursery ground. The fringe of the short cirri present on the ventral side of the lower jaw in the juvenile stages alone may be associated with their peculiar feeding habit of capturing small benthic organisms from muddy regions of the mangrove environment.
5. Capture fisheries and utilization
The juveniles of this species are subjected to destructive fishing in the mangrove waters by cast-nets, drag-nets and shooting nets. Adults are caught by hand lines and bottom trawls (Fischer and Whitehead, 1974). The bigger sized fish, when caught by Taiwanese fishermen, are considered as a prize catch due to its taste and high price. But in South India it does not find a top rank in the markets – probably due to the fact that taste differs from person to person, race to race, region to region, and according to cooking methods. It is marketed mostly in a fresh condition.