1. Introduction
Tetraodontiformes is a special group of higher teleost fishes, famous
for the name of “puffer fish”. It is believed that puffer fish is the
general name of fishes in family Tetraodontidae of order
Tetraodontiformes. However, there is also a view that all species in the
order Tetraodontiformes are called as puffer fish (Wu & Chen, 1981).
The species in this order are very abundant and distributed in various
habitats, such as freshwater, brackish and coastal waters, open seas and
so on (Yamanoue et al., 2008). So far, FishBase
(https://www.fishbase.de/)has recorded 446 species of Tetraodontiformes,
belonging to 106 genera and 10 families. According to the records of
“Fauna Sinica”, there are 131 species in 61 genera of 10 families in
China (Su & Li, 2002), one of them is freshwater fish.
Tetraodontiformes are distributed in a considerable amount along the
coast of China, and occupy an important economic position in Chinese
fishery (Su & Li, 2002). Among them, Thamnaconus ,Takifugu and Lagocephalus are with high economic value.
The puffer fish has a long edible history in China and Japan, and it is
regarded as a precious aquatic product for its high protein content and
extremely delicious taste. Although most of the puffer fishes taste
delicious and have high economic value, many of them contain toxic
tetrodotxin (TTX) in the ovary, liver, kidney, eyes and blood. If they
are not handled properly or eaten by mistake, people will be poisoned or
even die. Therefore, it is urgent to screen the species of edible puffer
fish and avoid the occurrence of puffer fish poisoning. The taxonomy and
identification of puffer fish is the key to solve the above problems.
In the traditional taxonomy, the classification and identification of
Tetraodontiformes are mainly based on the morphological characteristics
of stripes, spots, body color, and mouth shape, etc. However, the
morphology of closely related species of this order is very similar and
difficult to distinguish. Whether professionals or non-professionals, it
is an extremely difficult task to identify Tetraodontiformes fishes only
according to their morphological characteristics. So far, there are a
large number of synonyms in the order Tetraodontiformes (Liu et al.,
1999; Song et al., 2001; Cui et al., 2005; Reza et al., 2008; Matsuura,
2010; Sakai, Sakamoto, & Yoshikawa, 2021), and the classification and
identification of species are confused, which makes it difficult to
accurately count the number of species of this order (Chen & Zhang,
2015; Su & Li, 2002). Moreover, most of the commodities of the puffer
fish in the market have been processed and lost their original
morphological characteristics, which makes it impossible to identify
species. DNA barcoding is used to identify species at molecular level,
which is not affected by time, region and individual morphology (Hebert,
Ratnasingham & Waard, 2003). Combining the morphological
characteristics of species and DNA barcodding technology to identify
species will make the identification results more objective and
reliable.
At present, there have been many reports on the study of puffer fish at
the molecular level. However, these studies only focus on one genus or
several species of Tetraodontiformes (Song et al., 2001; Elmerot et al.,
2002; Ishizaki et al., 2006; Reza
et al., 2008; Zhang & He, 2008; Santini, 2013; Chen, 2019), and there
is no study on the species identification of the whole order
Tetraodontiformes. Therefore, it is urgent to carry out accurate
classification and identification research of order Tetraodontiformes,
so as to improve technical support for food safety of fishery biological
sources and trade regulation of aquatic products.
In order to solve the difficulty of morphological classification of
Tetraodontiformes, this study used DNA bar code technology and
morphological methods to identify 616 samples of Tetraodontiformes
collected from the coast of China, clarified the synonyms of some
species of this order, and confirmed the effective species names of
these species Building a perfect classification system of DNA barcode
for the order Tetraodontiformes, will not only enrich the database of
fish DNA barcode, but also promote the rapid development of puffer fish
taxonomy and systematics, and provide technical support for aquatic
product quality safety and trade supervision.