Stomatopoda of Greece: an annotated checklist

Abstract Background The checklist of Stomatopoda of Greece was developed in the framework of the LifeWatchGreece Research Infrastructure (ESFRI) project, coordinated by the Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC) of the Hellenic Centre for Marine Research (HCMR). The application of the Greek Taxon Information System (GTIS) of this project has been used in order to develop a complete checklist of species recorded from the Greek Seas. The objectives of the present study were to update and cross-check all the stomatopod species that are known to occur in the Greek Seas. Inaccuracies and omissions were also investigated, according to literature and current taxonomic status. New information The up-to-date checklist of Stomatopoda of Greece comprises nine species, classified to eight genera and three families.


Introduction
Stomatopoda, also called "mantis shrimps or mantis prawns", is one of the most distinctive orders of Crustacea. They were well known from ancient times since Aristotle, the greatest of all naturalists, who described, for the first time in detail, the external morphology of the mantis shrimp Squilla mantis (Voultsiadou andVafidis 2007, Voultsiadou et al. 2017). They are common members of benthic ecosystems in tropical and subtropical marine waters throughout the world (Müller 1994). However, only a small number of species are known from temperate seas (Ahyong 2012). Mantis shrimps construct burrows in soft bottoms or live in crevices and holes of hard substrates (Müller 1994). Their larval development occurs in the plankton (Özel 1985). They are amongst the most efficient crustacean raptorial predators, having unique adaptations for hunting their prey (Ahyong 2012). They are often caught by trawls in commercial shrimp operations. In some parts of the world, mantis shrimps are considered a delicacy and consequently are fished commercially and marketed (e.g. Japan, Vietnam, Philippines and China). In Mediterranean countries, only Squilla mantis and Erugosquilla massavensis reach marketable densities and constitute a target for local fisheries (Colmenero et al. 2009).
Taxonomy of stomatopods still causes several difficulties for non-taxonomic specialists who only want to determine their specimens within the scope of non-taxonomic studies. Fortunately, several revisions, reviews and re-descriptions are available for this group of animals, though numerous short publications are scattered over many journals (Müller 1994). Consequently, 450 species of stomatopods are known worldwide, arrayed in 7 superfamilies, 17 families and over 70 genera (Ahyong 2012). Amongst these, only 12 stomatopod species are known in the Mediterranean Sea after a few studies carried out in this region (Manning and Froglia 1979, Abelló et al. 1993, Dounas and Steudel 1994, Özcan et al. 2008, Colmenero et al. 2009, Ounifi-Ben Amor et al. 2015. The only contribution to the Greek records of the taxonomic group of Stomatopoda has been made by Dounas and Steudel (1994). During several biological investigations along the continental shelf of Crete (1988)(1989)(1990)(1991), an interesting collection of stomatopod crustaceans was obtained from soft substrates in depths ranging from 10 to 200 m. Since then, no new species records have been provided. Data on the occurrence and distribution of stomatopods in the Greek Seas remain scarce (Kevrekidis andGalil 2003, Dimitriadis et al. 2019).
The first attempt for developing a checklist of Stomatopoda was carried out within the framework of the "Greek Biodiversity Database" project, coordinated by the Aristotle University of Thessaloniki in Greece (2005Greece ( -2008. In 2010, a database was set up online in order to record the occurrence of these marine species in the Greek Seas. The World Register of Marine Species (WoRMS Editorial Board 2020) and the European Register of Marine Species (ERMS, now part of WoRMS) created the reference of Koukouras (2010) in order to include the list of these marine species provided by the Greek Biodiversity Database during the European project PESI.
The aim of the present study was to provide an updated checklist of Stomatopoda of the Greek Seas. For this purpose, an older list of stomatopod species was updated and annotated according to recent literature and current taxonomic status of the species.

Materials and methods
The annotated checklist of Stomatopoda of Greece was developed within the framework of the LifeWatch Greece Research Infrastructure (ESFRI) project and coordinated by the Hellenic Centre for Marine Research during the period 2013-2015 (Arvanitidis et al. 2016). Bailly et al. (2016) give the general principles used for elaborating the annotated checklist of Stomatopoda of Greece. The checklist of Stomatopoda was constructed, based on the classification and species records, listed as present in Greece and extracted from the dataset of WoRMS/ERMS for marine species (Koukouras 2010, Costello et al. 2020. Then, all relevant publications were reviewed and the species reported to date have been added to the list. All Stomatopoda records were cross-checked for their taxonomy in WoRMS (WoRMS Editorial Board 2020). The main synonyms are presented for each species under the "Nomenclature" field. Non-indigenous species are marked in the "Native status" field. Detailed information is also presented with regards to the distribution, bathymetric range and biotopes for each species in the Greek Seas and adjacent regions, along with key references, based on a thorough literature review.

Discussion
Only twelve stomatopod species are known in the Mediterranean Sea, including three aliens of Indo-Pacific origin: the mantis shrimps Erugosquilla massavensis and Clorida albolitura, as well as the erythrosquillid Erythrosquilla sp., yet unidentified, that has been reported, based on a post-larval specimen collected from plankton in the Ligurian Sea (Colmenero et al. 2009). With the exception of Squilla mantis, Rissoides pallidus and, to a lesser degree, Rissoides desmarestii, which are rather commonly captured by trawling (Colmenero et al. 2009), studies concerning data on the occurrence and distribution of other stomatopods in this region are much fewer (e.g. Lewinsohn and Manning 1980, Ranieri and Mori 1991, Ranieri and Mori 1994, Dounas and Steudel 1994, Abelló et al. 1993, El Lakhrach et al. 2012, Bakır and Çevirgen 2012).
The updated checklist of Stomatopoda of Greece includes a total of nine species, classified into eight genera and three families. Recently, checklists for marine crustaceans such as Cumacea, Mysida and Lophogastrida have also been published from the Greek Seas (Koulouri et al. 2016a, Koulouri et al. 2016b). As mentioned above, after Dounas and Steudel (1994), who studied the stomatopods along the continental shelf of Crete and therefore largely contributed to the Greek records of this taxonomic group, no new species records have been provided. Until recently, only scattered distribution data of already recorded stomatopod taxa have been published (e.g. Kevrekidis andGalil 2003, Dimitriadis et al. 2019). Moreover, further research is needed for the verification of the presence of the stomatopod species Pseudosquillopsis cerisii in the Greek Seas as, apart from a very old record from the south coast of Peloponnese (Guérin 1832), it has never been reported from the eastern Mediterranean. Finally, working on the molecular delimitation of stomatopods of the Greek Seas is necessary, in order to investigate the possible occurrence of cryptic species in future studies.
The distribution of the eight out of the nine Stomatopoda species of the Greek Seas (excluding Squilla mantis which is extremely common and widely distributed) across the Mediterranean basin is presented in Fig. 1. The only erythrean species E. massavensis present in the Greek waters (Saronikos Gulf, Crete, Rhodes, Karpathos and Zakynthos islands) until now has also been recorded along the coasts of Turkey, Syria, Cyprus, Lebanon, Israel, Egypt, Libya, Sicily, Malta, Tunisia and even from the Sea of Marmara (Shakman and Kinzelbach 2007, Özcan et al. 2008, Ounifi-Ben Amor et al. 2015, Corsini-Foka et al. 2017, Zenetos et al. 2018, Gianguzza et al. 2019, Stern et al. 2019.