(Hardenberg)
1. Distinctive characters of early developmental stages
(a) Eggs (Largely after Nair, 1952b, Thangaraja, 1987 and Delsman, 1931)
Stolephorus macrops 1
Pelagic, transparent, elliptical, length 1.15 -1.3 mm; breadth 0.53 - 0.63 mm; perivitelline space very narrow; segmented yolk occupies the entire length of the egg; slightly brownish or yellowish oil, globule with 0.1 - 0.12 mm diameter is present at the posterior end of the yolk; small vacuole-like structure present above the oil globule; yolk and embryo without any pigmentation.
(b) Larvae (After Nair, 1952b, Thangaraja, 1987 and Delsman, 1931)
Stolephorus macrops 2
Newly hatched transparent prolarva measures 3.45 mm in length and the oil globule is still present at the posterior end of the tapering yolk mass. Pectoral fins form as a small prominence just above the yolk mass in the prolarva. In one day old larva, the yolk mass and oil globule disappear and the mouth has formed. At 3.8 mm length, the pectoral fins and caudal fin rays are clearly visible. The pre-anal myomeres gradually decrease from 29 to 21 and the corresponding post-anal myomeres increase from 10 to 18 during the forward movement of anus/anal fin as the larva grows. Anal fin origin not yet reached dorsal base in postlarval stage. Pigments appear in 4 mm larva after the colouration of eyes. Pelvic fins develop after 20 mm size. In advanced post larvae, 1-2 stellate pigments appear in the isthmus, 2-3 on pectoral base, 7 between pectoral and pelvic fin origin lateroventrally and 12 on anal base. Dorsal spine and ventral scutes not yet developed. Alimentary canal has vertical muscle strand.
(c) Early juveniles (Largely after Termvidchakorn, 1989)
Stolephorus macrops 3
The early juveniles of 28-30 mm size show the presence of ventral scutes and there is no spine on pelvic scute. Hind border of pre-operculum slightly indented near manilla tip; snout short and blunt; predorsal spine is present; scales start developing.
2. Distinctive characters of early developmental stages in similar species occurring in the mangrove waters
(a) Eggs
1) Stolephorus heterolobus
Yolk occupies two third the length of Egg; No vacuole-like structure above the oil globule.
2) Stolephorus tri
Longer eggs (up to 1.7 mm length) with relatively smaller (0.08 mm diameter) yellowish or light brownish oil globule.
(b) Larvae
1) Stolephorus heterolobus
Predorsal spine absent; maxilla pointed posteriorly, projecting beyond anterior border of preoperculum (Whitehead, 1972).
2) Stolephorus tri
Early juveniles measuring 25 mm possess 23 pre-anal myomeres. Pelvic scute with pungent spine present in juveniles of 29-31 mm standard length distinguishes this species from all other species of Stolephorus . Hinder border of preoperculum evenly rounded near maxilla tip (Whitehead, 1972; Ronquillo, 1970).
3. Distinctive characters of early developmental stages in similar species occurring in the mangrove waters
(a) Eggs
1) Eggs of Stolephorus bataviensis and S. commersonii
Elliptical eggs passes a distinct terminal knob.
2) Eggs of Stolephorus indicus
Pear shaped eggs with a terminal knob.
(b) Larvae
1) Larvae of Stolephorus heterolobus
Relatively more number of myomeres (42-43). (In the case S. macrops, only 38-39 myomeres are present).
4. Salient ecological information
Among the species of the genus Stolephorus , the eggs of Stolephorus macrops (with an oil globule) are common in brackish waters and mangroves with salinity range of 25 to 33.5 ppt and the larvae and early juveniles occur even from 15 to 33.5 ppt salinity. This species coeurs in east and west coast of India, Indo-Malayan archipelago, Thailand, Hong Kong and Taiwan.