中国对虾、墨吉对虾和长毛对虾仔虾的发育比较研究

COMPARATIVE STUDY ON POSTLARVAL DEVELOPMENT OF PENAEID SHRIMP PENAEUS CHINENSIS, P.PENICILLATUS AND P. MERGUIENSIS

中国海域已报道的约90种对虾中,半数具有经济价值。其中中国对虾、墨吉对虾和长毛对虾无论在捕捞还是在养殖业上都具有十分重要的地位。由于3种虾的形态非常相近,特别是在早期生活史阶段,它们的幼体和仔虾很难区分,因而给对虾种群补充、预报和其它有关研究造成困难。尤其在热带海域,对虾生殖季节重叠,幼体和仔虾的鉴别更加重要,各期仔虾的数量统计需以严格的形态鉴别作为依据。作者对三种对虾的幼体的形态,区别已有专文报道(Liu and Liu,1994)。本文深入细致地研究了中国对虾、墨吉对虾和长毛对虾仔虾的发育形态学,并进行了比较,使3种对虾的仔虾得以区别,并为今后的对虾生态学研究及资源管理奠定基础,提供依据。

The postlarval developments of Penaeus chinensis, P. merguiensis and P. penicillatus are described and fully illustrated. Study results on their comparative morphology are made and concluded as follows;1. After the 5th postlarva. the rostrum.to carapace ratio of P. merguiensis increases much more rapidly than that of P. chinensis and P. penicillatus- (Fig. 49, Table 16,17,18). It reaches the highest of 1.50 in the 12th postlarva of P. merguiensis, 1.10 in the 6th postlarva of P. chinensis and 1 . 23 in the 15th postlarva of P. penicillatus. However, after reaching the highest,ratio, it decreases fastest in P. merguiensis, less fast in P. penicillatus and slowest in P. chinensis, which may explain that this ratio is largest in P. chinensis, in-between in P. penicillatus and smallest in P. merguiensis during their adult stages.2. Antennal spines exist in all postlarval substages of P. chinensis(Fig. 2), disappear during 3rd (or 4th)-8th (or 9th) postlarva oi P. merguiensis (Fig. 19) and 2nd (or 3rd) -6th (or 7th) postlarva of P. penicillatus (Fig. 34).3. The dorso-median spine on the 5th abdomen disappears from the 6th or 7th postlarva of P. chinensis (Fig. 3) and P. penicillatus (Fig. 35), disappear in 9th or 10th postlarva of P. merguiensis (Fig. 20).4. The process at the center of the posterior margin of the telson appears in the 6th postlarva of P. chinensis (Fig. 4,5) and P. penicillatus (Fig. 36), in the 9th or 10th postlarva of P. merguiensis (Fig. 21).5. After the 10th postlarva, the ratio between the outer and inner flagellum of the antennule of P. chinensis (1.17-2.11) becomes much larger than that of P. merguiensis. (0.87 -1.10) and P. penicillatus .(0.95 - 1.15) (Fig. 50. Table 7,8,9). 6. The exopods of 3rd maxilliped and pereiopod 1-5 in postlarval stages of P. chinensis(Fig. 13, 14, 15) degenerate more slowly than that of P. merguiensis (Fig.29, 30, 32) and P. penicillatus (Fig.44, 45, 47). In postlarva 1-3, there are 9 plumose setae on the expods of the third maxilliped and pereiopod 1-5 in P. chinensis, only 8 or less than 8 in the latter two; in the 4th postlarva, the exopods of the 3rd maxilliped and pereiopod 1 - 5 P.chinensis can still reach the meropodites and have plumose setae, while those of the latter two can not reach beyond the middle of the ischium and have no setae.7. The endopod of first pleopod appears 4 substages earlier in P. chinensis (Fig. 18, Table 13) than those of P. merguiensis (Fig. 33, Table 14) and P. penicillatus (Fig. 48, table 15) which appear in the 11th or 12th postlarva.A tentative key is provided for the identification of postlarva 1-22 of P. chinensis, P. merguiensis and P. penicillatus and the criteria for distinguishing the postlarval substages was presented so as to make the key more workable.P. chinensis can be distinguished from P. merguiensis and P. penicillatus during all the postlarval stage, while the latter two can not be distinguished untill the 7th postlarva.The morphological difference between P. penicillatus and P. merguiensif in the postlarval stages is much less than that between each of them and P.chinensis, and is similarly the case with the adult stage when there is closer affinity between P. merguiensis and P. penicillaius.