Morphological comparison of Oratosquilla oratoria stocks along the coast of Haiyang and Yantai

Abstract:

In spring (April) of 2017, Oratosquilla oratoria samples were collected three times near the coast of Haiyang and Yantai. Twelve morphological parameters were measured by traditional morphological method of linear measurement. Fifteen proportional trait indexes were calculated and compared by multiple statistical methods such as Independent-Sample t-test, CD test, principal component analysis, and discriminant analysis. The t-test and CD test results showed that the samples from Haiyang (Haiyang stock) had a longer and thinner body shape than those from Yantai (Yantai stock). The carapace, tail, and raptorial claw of the Yantai stock, whereas the abdomen of the Haiyang stock constituted larger proportion of the total length of the organism. Although there were significant differences in the length of the carapace, thoracic somite, tail, and the propodus between the two stocks (P<0.01), they did not reach the level of subspecies (CD<1.28), characterized by morphological differences between different geographic groups within the same species. According to the principal component analysis, the female stock constructed three principal components with a cumulative contribution rate of 87.571%. The male stock also constructed three principal components with a cumulative contribution rate of 83.156%. The difference in the transverse body shape factor between Haiyang and Yantai stocks was clear. The discriminant function of stocks was established by discriminant analysis and the comprehensive discriminant accuracy was 74%. These results showed that O. oratoria shrimps were species with sexual dimorphism. The difference in adult morphology is more evident, particularly in males between Yantai and Haiyang stocks.