Biology of Finfish and Shellfish

4.12.10. Protozoea III

MTL: 2.69mm (2.41-2.73 mm); MCL: 1.01 mm (0.98-1.05 mm).

Supraorbital spines not bifurcate, telson demarcated from 6th abdominal segment by an articulating joint, abdominal segment 1 to 5 with dorsomedian spine on posterior border, 5^th and 6th abdominal segments have each a pair of posterolateral spines 6th segment devoid of posteromedian dorsal spine, but with a pair of ventrolateral spines, caudal furcae bear 8 setae each, a pair of biramous uropods present, exopod of uropod slightly longer than endopod and bears 6 terminal setae, endopod has 2 terminal setae, buds of pereopod and Mxp3 well developed and biramous, exopod bud of Mxp3 with 3 terminal setae in advanced larvae of this sub stage, exopod and endopod of uropod are almost of same size and uropod rami reach much beyond middle of telson an increase in length of biramous buds of thoracic legs is also noticed.

A1 3 segmented, sub segments of basal segment fused into one, basal segment with one distal seta, 2nd segment with 2 lateral setae and 3 to 4 setules, distal segment with 3 or 4 aesthaetes and 3 setae of which one is long being more than twice length of peduncle, distal segment appears to be the forerunner of outer A1 flagellum; Md asymmetrical, between incisor and molar processes there are 6 free standing teeth in left Md and 2 free standing teeth in right Md; Mx1 with 10 setae on distal endite of protopod while setation on proximal endite remains unchanged; Mx2 with more setae on protopod endites, exopod and endopod remaining unchanged; Mxp1 with 8 setae on coxa and 12 setae on basis of protopod and 9 setae on exopod; Mxp2 with 7 setae on exopod and one additional seta on outer margin of 1^st segment of endopod, protopod with 2 setae on coxa and 5 setae on basis. Duration of this sub stage was 24 to 36 hours.