| Helice tientsinensis is widely distributed in coastal provinces of China. It lives in caves on the beaches of estuaries and occurs in large numbers. Its larvae naturally occur and usually mix with those of Eriocheir sinensis in the mouth of Changjiang River and the neighbouring waters. How to distinguish them from each other is important for crab culture using E.sinensis larvae captured from natural waters.
This paper deals detailedly with the complete larvae development of H.tientsinensis reared in the laboratory. The present species passes through five zoeal stages before matamorphasis to the megalopal stage attained about 21 days after hatching. The culture was carried out at 20-24℃, salinity 15 and 200-400 lx photo intensity. Morphological characteristics of each larval stage of H.tientsinensis are compared with those of E.sinensi.
The significant difference between the zoeae of H.tientsinensis and of E.sinensis is that the dorsal, rostral and lateral spines on the carapace are smooth in the former while those in the latter have denticles. Besides, the numbers of setae on the maxillule and maxilla of zoeae of the former are less than that of the latter.
Megalopas of the two species can be briefly distinguished as follows. Firstly, there are two indistinctly rounded lobs on the antero-lateral margins of the E.sinensis carapace while there is none on those of H.tientaiensis. Secondly, pereiopod 2-4 each with 3-4 ventral teeth on dactylus of E.sinensis; 3-4 ventral spines on that of H.tientsinensis. Thirdly, the expos of pleopods 1-5 of E.inensis with 23, 21, 21, 19, 12 long natatory plumose setae; with 18, 17, 17, 16, 10 long natatory plumose setae on that of H.tientsinensi. |
