Introduction
Freshwater prawns mainly refer to certain species of Caridean (Decapoda: Caridea). It is a highly species-rich group with a long taxonomic history, but at the same time its taxonomic status is controversial. There are about 770–800 Caridea species in freshwater, accounting for about one-fifth of the shrimp described (De Grave et al., 2015 ). At present, freshwater shrimps are only exist in 7 families of 38 currently Caridea families (De Grave, Li, Tsang, Chu, & Chan, 2014 ). Among them, the two families of Atyidae and Palaemonidae are quantitatively dominate, comprising 443 and 300 species respectively, which account for 97.4% of all freshwater shrimp species (De Grave et al., 2015 ). Shrimp play an important role not only as an important component of biodiversity but as a very good source of animal protein for people. In addition, freshwater shrimp has high economic value, nutritional value and research significance (Holthuis, 1980 ;New & Nair, 2012 ). Therefore, the taxonomic identification and species identification of shrimp is one of the most important tasks for all kinds of related biological research and fishery resource conservation and management(Shen, Guan, Wang, & Gan, 2016 ) .
There have been many studies on freshwater prawn fauna, but it is poorly known of Henan Province, China. So far, 8 species of shrimps have been reported. The survey used traditional morphological recognition methods to identify and morphologically describe 352 samples of 8 species that from 15 sampling points (F. Wang, 1989 ). Henan province is located in inland, there are four major river systems, such as the Yellow River, the Yangtze River, the Huaihe River and the Haihe River. But studies on the freshwater prawns of this area are rather scanty. In view of the above, it is of great significance to enrich shrimp related researches in Henan province to append the list of shrimp species and assess the biodiversity of this area.
The study of species diversity is the basis of all biological research, but at the same time it is also a huge challenge and a harsh burden(P. D. Hebert, Cywinska, Ball, & deWaard, 2003 ). As the main method of species diversity research, traditional morphological identification has high requirements and restrictions on samples and researchers, and the identification results are greatly affected by subjective and objective factors(Carvalho, Neto, Brasil, & Oliveira, 2011 ; P. D. Hebert, Cywinska, et al., 2003 ; Shen et al., 2016 ). In recent years, DNA barcode technology has developed rapidly and has gradually become one of the main methods for biological identification. With the implementation of the Barcoding of Life project, DNA barcodes have been widely recognized as a basic tool for species identification, mitochondrial gene cytochrome C oxidase I (COI ) serves as the core of the global animal biometric system could effectively distinguish Crustacea (Costa et al., 2007 ;P. D. Hebert, Cywinska, et al., 2003 ; P. D. Hebert, Ratnasingham, & deWaard, 2003 ). However, the successful application of DNA barcodes is also affected by many factors, as an important part of DNA barcode technology, the establishment of a standard life barcode library is of great significance. In the era of high-throughput sequencing, there is high probability of tentative, incorrect, or low-quality sequences being submitted to databases (L. L. Wong et al., 2011 ). Therefore, compared with the commonly used barcode databases GenBank (NCBI), DDBJ, EMBL, etc., the BOLD database, which conducts strict review and screening of submitted data, is relatively more accurate and applicable(Macher, Macher, & Leese, 2017 ; Z. Wang et al., 2009 ). In addition, as the fundamental units in biological research, species can be defined on the basis of various operational criteria. At the same time, with the acquisition of a large number of barcodes, there has been growing use of molecular approaches for species delimitation (P. D. N. Hebert & Gregory, 2005 ; Luo, Ling, Ho, & Zhu, 2018 ). At present, sequence analysis for species delimitation mainly includes tree based method, distance based method and character based method, of which the first two have higher universality and applicability (Birch, Walsh, Cantrill, Holmes, & Murphy, 2017 ). The combined use of multiple molecular methods will improve the accuracy of the species definition results. Therefore, as many different types of molecular methods as possible should be used for comprehensive species definition.
In fact, both morphological identification and molecular definition are supporting tool for species identification. The combination of multiple methods will produce more objective and real species identification results, the species boundaries will be clearer. The main aim of this study was to objective and truthful assessment the shrimp diversity at both taxonomical and molecular level, and provides helpful information for future conservation and fisheries resource management of the shrimp in Henan.