As noted above, five species included in Zariquiey Álvarez (1968) should not be considered as present in Iberian waters:

1. Parthenope miersii (A. Milne-Edwards and Bouvier, 1898)

This species has been collected only twice, the first time corresponding to a male collected at 112 m depth in the Gulf of Cádiz and used as holotype by A. Milne-Edwards and Bouvier (1898, 1900) and the second time corresponding to another male at 135-150 m depth in the Cape San Vicente (Nunes-Ruivo 1961). D’Udekem d’Acoz (1999) questioned the validity of this species based on two male specimens only, and Türkay (2001) considered that P. miersii is a synonym of Spinolambrus macrochelos.

2. Portunus sayi (Gibbes, 1850)

The records of this species in Cabo Espartel (NW Africa close to Gibraltar Strait) and in the Balearic Islands (Zariquiey Álvarez 1968) should be considered juveniles of Portunus hastatus according to Türkay (1987).

3. Euchirograpsus americanus A. Milne-Edwards, 1880

This species is only distributed in the western Atlantic, and all reports in Mediterranean and eastern Atlantic must be referred to E. liguricus (see Türkay 1975).

4. Grapsus grapsus (Linnaeus, 1758)

This species was reported along the coast of Portugal, once in Setubal (Osório 1905) and later on in Sesimbra (Vilela 1936). G. grapsus is mainly distributed in the western Atlantic, while Grapsus adscensionis is the main eastern Atlantic species of this genus (see Manning and Chace 1990). It is hard to imagine that G. grapsus could occur along the Iberian coast and pass unnoticed, taking into account the habitat (intertidal rocky shores) and typical size of this species. Given that there are no other reports for these species along the Iberian coast, G. grapsus was not included in this checklist.

5. Percnon planissimum (Herbst, 1804)

Zariquiey Álvarez (1968) reports this species as rare in the coastal and sub-coastal waters of Portugal. No reports have been published confirming its presence in Iberian waters. In the last few years though, Percnon gibbesi has been collected throughout the Mediterranean, and specifically from Mediterranean localities on the Iberian coast.

New species present in Iberian waters (since 1968)

In this first group we have included 10 species new to science and reported in Iberian waters after the work of Zariquiey Álvarez (1968). Note that Monodaeus guinotae is considered as an invalid species and is not included in the checklist.

1. Homologenus boucheti Guinot and Richer de Forges, 1995

This deep-sea species was described to comprise the eastern Atlantic populations of Homologenus rostratus (A. Milne-Edwards, 1880). In the Iberian Peninsula, it had only been reported (as H. rostratus) in the south of Portugal (García Raso 1996).

2. Calappa tuerkayana Pastore, 1995

This new species was described by Pastore (1995) from the Ionian Sea, and has been reported in the Balearic Islands (García 2002, García and Corbera 2007) and Atlantic waters (d’Udekem d’Acoz 2001). The validity of C. tuerkayana was already questioned by Holthuis (2001), and new molecular evidence indicates that this species represents juvenile stages of Calappa granulata (Abelló and Palero in prep.). Therefore, C. tuerkayana should be excluded from the Iberian checklist in the near future.

3. Pisa sp. Marco-Herrero et al. (in prep.)

A megalopa stage collected in Balearic waters has been assigned to the genus Pisa using molecular data. However, the DNA sequence obtained does not correspond to any of the species of this genus found in Iberian waters (Marco-Herrero et al. in prep.). In addition, a small specimen of this genus, morphologically different to other known Iberian species, has been found in the Alboran Sea (García Raso et al. unpublished).

4. Macropodia deflexa Forest, 1978

Forest described this Macropodia species as being closely related to M. czernjawskii, and its taxonomic validity has been questioned by d’Udekem d’Acoz (1999). The species has been reported in the Gulf of Biscay, Galicia, Portugal and the Gulf of Cádiz (Forest 1978, Fernández Cordeiro et al. 2006).

5. Macropodia parva Van Noort and Adema, 1985

D’Udekem d’Acoz (1999) suggested that this species could be attributed to juvenile stages of M. rostrata. Molecular evidence obtained by the authors support this assumption (Marco-Herrero et al. in prep.), so this species should also be excluded from the Iberian checklist in the near future.

6. Maja brachydactyla Balss, 1922

This species was established by the recognition of two distinct taxa within M. squinado sensu lato: M. squinado sensu stricto in Mediterranean waters and M. brachydactyla in Atlantic waters. The first hints given by Neumann (1998) were recently confirmed by DNA analyses (Sotelo et al. 2008). It should be pointed out that M. brachydactyla is also known to occur in the western Alboran Sea (Abelló et al. 2014).

7. Pilumnus sp. d’Udekem d’Acoz and Schubart (in prep.)

The taxonomy of Pilumnus is controversial, with no clear distinction between several species (d’Udekem d’Acoz 1999, Mavidis et al. 2009). Recent molecular studies on the European representatives of this genus have established six different operative taxonomic units, one of them corresponding to a yet undescribed species present in the Gulf of Cádiz (Oliveira-Biener et al. 2010, Schubart and Aichinger 2013).

8. Chaceon mediterraneus Manning and Holthuis, 1989

This deep-sea species is known so far from Mediterranean waters only. It has been reported in both the western (Cartes 1993) and eastern (Kitsos et al. 2005) Mediterranean basins.

9. Chaceon inglei Manning and Holthuis, 1989

This species was described based on a female specimen obtained during the Challenger expedition. It has been reported from Iceland, Scotland, southwest England, the Bay of Biscay, Madeira, and the Canary and Azores Islands (Manning and Holthuis 1989). In Iberian waters, it has been reported (as Geryon affinis) off Vigo (northwest Spain) (d’Udekem d’Acoz 1999, Araújo et al. 2009).

Invalid species:

1. Monodaeus guinotae Forest, 1976

This species has been recorded in southwest Portugal (d’Udekem d’Acoz 1999), southwest Spain, the Alboran Sea (García Raso 1996) and the Balearic Islands (García and Gracia 1996). The differences between this species and Monodaeus couchii are very small, and Mavidis et al. (2008) consider this species identical to M. couchii. Indeed, the recent molecular phylogeny study by Reuschel and Schubart (2006) indicates that M. guinotae should be considered a synonym of M. couchii.

This second group includes 17 species that were known by 1968 but had not been reported in Iberian waters. It also includes one invalid species:

1. Cymonomus normani Lankaster, 1903

This eastern Atlantic species was reported in Portuguese waters by Türkay (1976).

2. Calappa pelii Herklots, 1851

This is a West African species collected once in the Chafarinas Islands (Silvestre, identification confirmed by Galil et al. 2002)

3. Cryptosoma cristatum Brullé, 1837

This species has been reported from the Macaronesian archipelagos (Madeira, Azores, Canarias, Cape Verde), and also in Málaga and Alboran Sea by García Raso (1993). There is an unpublished photography of a specimen collected in Algarve (Portugal) in 2008 (M.M. Rufino pers. comm.).

4. Ethusina talismani A. Milne-Edwards and Bouvier, 1897

This is a West African species, reported from South Portugal by García Raso (1996).

5. Paragalene longicrura (Nardo, 1869)

This is a rare species with a wide distribution, from the Aegean Sea (eastern Mediterranean) to Madeira (eastern Atlantic), reported in the Balearic Islands by García Socias (1985) and Gili and Macpherson (1987).

6. Pisa carinimana Miers, 1879

This species is known to occur from the Canary Islands (topotypic locality) to Angola, and was recently observed for the first time in Madeira (Ramalhosa et al. 2014). It was collected in Melilla (Mediterranean North Africa) by Zariquiey Álvarez (1968) and for the first time in the Alboran Sea by García Raso (1981, 1984), and in the Gulf of Cádiz by González-Gordillo et al. (1990).

7. Velolambrus expansus (Miers, 1879)

Also reported as Parthenope expansa, this species is distributed from the eastern Atlantic to the eastern Mediterranean. It was collected from the Alboran Sea by García Raso (1989, 1996).

8. Chaceon affinis (A. Milne-Edwards and Bouvier, 1894)

This eastern Atlantic species was found off Galicia (Northwestern Spain) by González Gurriarán and Méndez (1986).

9. Geryon trispinosus (Herbst, 1803)

This species, very similar to the northeastern Atlantic G. longipes, has been captured off Galicia (Urgorri et al. 1990) and Portugal (Vilela 1936, Türkay 1976).

10. Liocarcinus maculatus (Risso, 1827)

This species has been confounded with L. pusillus and L. zariquieyi, but Froglia and Manning (1982) summarized their distinctive morphological traits. It is mainly present in the Mediterranean Sea, with some occurrences in the eastern Atlantic. It has been collected in the Alboran Sea (García Raso 1984, 1996) and along the Catalan coast (Abelló et al. 1988, 2002).

11. Liocarcinus mcleayi (Barnard, 1947)

A synonym of Xaiva mcleayi and Polybius mcleayi. It was recorded in Portugal (as Macropipus zariquieyi) by Neves (1978), and in the South of Spain (Barbate, Cádiz) by García Raso and Manjón Cabeza (1996).

12. Paractaea monodi Guinot, 1969

This species was reported from North Africa (Melilla) as Actaea rufopunctata (Zariquiey, 1968). Specimens (as Paractaea rufopunctata) were caught in the Alboran Sea (García Raso and Barrajón 1983, García Raso 1990). It is also known from the Balearic Islands (Corbera et al. 1993).

13. Microcassiope minor (Dana, 1852)

An Atlantic species that has also been reported from Almeria and the Alboran Sea (García Raso and López de la Rosa 1992).

14. Xantho sexdentatus (Miers, 1881)

This tropical and subtropical Atlantic species is distributed from Senegal to the western Sahara (d’Udekem d’Acoz 1999), and the closest records to the Iberian Peninsula so far correspond to the Azores and Canary Islands (Fransen 1991). A specimen, identified by DNA barcoding in the context of the MEGALOPADN project as X. sexdentatus, has been collected in Rota (Cádiz). This constitutes a new report for the Iberian fauna.

15. Brachynotus atlanticus Forest, 1957

This western Atlantic species has been reported for Iberian waters in the Gulf of Cádiz (García Raso 1985, González-Gordillo et al. 1990) and the Alboran Sea (García Raso 1984, 1985).

16. Afropinnotheres monodi Manning, 1993

This African pinnotherid was recently reported for the first time in the Gulf of Cádiz by Subida et al. (2011), which also constituted the first record in European waters. This was the third report for this species worldwide. Although it is probably a case of natural range expansion, an introduction by fouling should not be discarded, given that the mussel Mytilus galloprovincialis is one of its main hosts (Drake et al. 2014).

Invalid species:

1. Brachynothus gemmellaroi (Rizza, 1839)

The westernmost record for this Mediterranean endemic species was reported as B. gemmellari in the Ebro Delta (Guerao et al. 1995). Although it is still considered a valid species (e.g. WoRMS), initial DNA evidence suggests that B. gemmellari should be considered an ecophenotype of Brachynotus sexdentatus (Schubart et al. 2001).

Human introduction of alien/allochthonous species has become an important biodiversity concern (Zenetos et al. 2010). Crab species are not an exception and up to ten alien species have recently been found in Iberian waters, namely: Hemigrapsus takanoi, Eriocheir sinensis, Percnon gibbesi, Dyspanopeus sayi, Rhithropanopeus harrisii, Callinectes sapidus, Charybdis feriata, Callinectes exasperatus, Pachygrapsus gracilis and Pilumnopeus africanus (Cuesta Mariscal et al. 1991, Abelló and Hispano 2006, García-de-Lomas et al. 2010, Castejón and Guerao 2013, Marco-Herrero et al. 2013b, Almon et al. 2014, Cuesta et al. 2015). The first six species from this list show established populations in Iberian waters:

1. Hemigrapsus takanoi Asakura and Watanabe, 2005

The first European records of this varunid crab from Asia were identified as Hemigrapsus penicillatus (de Haan, 1835) since H. takanoi was not described at that time. Asakura and Watanabe (2005) described H. takanoi as a new species and differentiated it from H. penicillatus. In the Iberian coast, H. takanoi was first reported from Laredo (Gulf of Biscay) (Noël et al. 1997), and it is now well established in several localities of this region (Dauvin et al. 2009).

2. Eriocheir sinensis H. Milne-Edwards, 1853

The Chinese mitten crab is native to the east coast of China, from Hong Kong to North Korea. In the Iberian Peninsula, E. sinensis has been established in the Guadalquivir Estuary, SW Iberian Peninsula (Garcia-de-Lomas et al. 2010). It has been reported from the Tagus estuary (Cabral and Costa 1999) and Zumaia (Gulf of Biscay) (Martínez and Adarraga 2006), but there are no data about stable populations in these localities.

3. Rhithropanopeus harrisii (Gould, 1841)

The Harris mud crab is native to the Atlantic coast of North America, from the southern Gulf of Saint Lawrence (Canada) to the Gulf of Mexico. R. harrisii has been established in the Guadalquivir and Guadalete estuaries, SW Iberian Peninsula (Cuesta Mariscal et al. 1991, Rodríguez et al. unpublished data) and it was also reported in the Mondego estuary (Portugal) (Gonçalves et al. 1995).

4. Dyspanopeus sayi (Smith, 1869)

Say’s mud crab is native to the northwestern Atlantic Ocean from Canada to Florida. This species has been established in the Ebro Delta, NE Iberian Peninsula (Schubart et al. 2012, Marco-Herrero et al. 2013b).

5. Percnon gibbesi (H. Milne-Edwards, 1853)

Zariquiey Álvarez (1968) reported Percnon planissimum (Herbst, 1804) as being a species very rarely present in Portuguese waters, but these records have not been confirmed. Instead, the Atlantic species Percnon gibbesi has been recently recorded in different localities throughout the Mediterranean (see Katsanevakis et al. 2011). In the Iberian Peninsula, the species has been reported in the Balearic Islands (García and Reviriego 2000, Müller 2001), Alicante (Acosta 2003), the Columbretes Islands and Barcelona (Abelló et al. 2003), Murcia (Félix-Hackradt et al. 2010), Almeria (Junta de Andalucía, GEOBIO 2010), Valencia (Palero unpublished data) and Granada (de la Roza, personal comm.). Megalopa stages and early juvenile specimens have recently been collected from Cullera (Valencia). Citizen science reports, mediated through the website “Observadores del Mar”, show that the species is now widely reported along the Mediterranean coasts from Cape Palos to Catalonia, as well as in the Balearic Islands. It is not yet clear whether this Mediterranean expansion from the Atlantic is a natural process or was mediated by human activities (accidental transport in ballast water or specimens released from pet trade).

6. Callinectes sapidus Rathbun, 1896

Some adult specimens of the American blue crab were recently captured in the Ebro Delta, but more data are needed to determine whether this species is definitely established. The species can be considered rare in other areas of the Iberian Peninsula (Castejón and Guerao 2013), although a recent report of one ovigerous female from the Sado estuary might indicate the establishment of a small population (Ribeiro and Verissimo 2014).

Some casual reports are known for the remaining alien species of this checklist, including a single adult female of the Indo-Pacific portunid Charybdis feriata caught in Barcelona (Abelló and Hispano 2006), one male specimen of Callinectes exasperatus collected in the Bay of Cádiz (Cuesta et al. 2015), and four specimens of Pilumnopeus africanus and two specimens of Pachygrapsus gracilis collected in Galicia (NW Spain) by Almon et al. (2014).

When species native from distant localities are reported within Iberian waters, there is little doubt that they were introduced through human activities (intentional or accidentally). However, this is not necessarily the case for species native from nearby areas in West and North Africa which have been recently found in the Alboran Sea and Gulf of Cádiz (Calappa pelii, Cryptosoma cristatum, and Afropinnotheres monodi). These were not considered as introduced species in the present account, but this hypothesis cannot be discarded.

The scientific names of some species considered by Zariquiey Álvarez (1968) have changed due to new systematic studies or synonymizations, and these are listed in Table 2. Other systematic changes refer to higher taxonomic levels, and these will be addressed here.

The first main change in the systematics of brachyuran crabs after 1968 was the proposal of new sections and subsections by Guinot (1977, 1978, 1979), de Saint Laurent (1979, 1980), and Guinot and Bouchard (1998). Based on the male and female genital apertures, these authors separated brachyuran crabs into Dromiacea and Eubrachyura, or the subsections Podotremata, Heterotremata and Thoracotremata. Morphological and molecular analyses do not reveal monophyly within Podotremata, so the most recent classifications divide it into three sections: Dromiacea, Cyclodorippoidea and Raninoida (De Grave et al. 2009). According to these changes, the old term Reptantia (present in Zariquiey Álvarez 1968) was removed from the classification. Considering just those superfamilies present in Iberian waters, most changes correspond to splits of old taxa into several new superfamilies. For example, the superfamily Corystoidea (which comprised the families Atelecyclidae, Cancridae, Corystidae, Pirimelidae and Thiidae) now comprises Corystidae only, while Atelecyclidae and Cancridae have been placed in the new superfamily Cancroidea, and Pirimelidae and Thiidae have been relocated within the Portunoidea (Spiridonov et al. 2014). All changes at the superfamily level are listed in Table 3, including new family composition.

Some of the most important changes affect the assignment of genera to new families, which cannot be appreciated in Table 3. For example, the former Majidae family suffered important changes due to its elevation into a superfamily (Majoidea) and the elevation to family level of previous subfamilies: Majidae, Epialtidae, and Inachidae. Some authors have raised Pisidae as well (Hendrickx 1995), but we followed here the more conservative classification of Ng et al. (2008) considering Pisiinae as a subfamily of Epialtidae. A recent study based on larval morphology and DNA did not support a clear separation between epialtid and pisid crabs (Hultgren and Stachowitz 2008). Nevertheless, larval morphology and DNA data suggest that Ergasticus clouei should be moved from Inachidae to Oregoniidae, a family that was not present in Iberian waters (Marco-Herrero et al. 2013a).

Within the Grapsoidea superfamily, the former Grapsidae is now restricted to the previous subfamily Grapsinae, while other subfamilies that acquired familial level (e.g. Varunidae, Plagusiidae and Percnidae) are also present in Iberian waters (see Schubart et al. 2002, Schubart and Cuesta 2010). Some genera and species have also changed their placement, such as Euchirograpsus that was considered a Varuninae and is now within the Plagusiidae.

The superfamily Portunoidea is still under discussion. Geryonid crabs, which were previously considered as part of Xanthidae, now belong to Geryonidae. Schubart and Reuschel (2009) proposed a new taxonomy based on molecular evidence for the Pirimelidae (traditionally placed in Cancroidea), Polybiidae, Carcinidae and Thiidae (according to Ng et al. 2008, but currently in its own superfamily Thioidea), and these changes obtained further support from Spiridonov et al. (2014). Several portunoid genera are currently under study and new modifications are expected.

The Parthenopidae family has also experienced strong changes after the work of Tan and Ng (2007). In the case of Iberian species, all generic names have been modified (new combinations) and the three species of Parthenope are now considered as one species of Spinolambrus and the monotypic genera Derilambrus and Parthenopoides. The former parthenopid genus Heterocrypta, a monotypic genus also found in Iberian waters, is now named Distolambrus.

Another important change affects the systematic position of Asthenognathus atlanticus, a former pinnotherid crab that is now considered a member of the subfamily Asthenognathinae (Grapsoidea: Varunidae). This modification, based on larval and molecular evidences provided by Cuesta et al. (2005), was already included in Ng et al. (2008).

Within the Ocypodidae, Spivak and Cuesta (2009) proposed to elevate the subgenus Afruca to genus level, based on larval morphology and supported by previous phylogenies of the genus Uca, and then named the species inhabiting the southwest of the Iberian Peninsula as Afruca tangeri. However, this proposal has not been followed in later studies and Afruca tangeri is maintained in this checklist as Uca (Afruca) tangeri.

Finally, morphological studies by Forest (1978) and García Raso et al. (1987) have questioned the validity of Macropodia longipes and considered its possible synonymy with Macropodia tenuirostris. Studying the larval development of both species, Guerao and Abelló (1997) also mentioned that “… the two species are closely related phylogenetically”. Both species are maintained as reported in Zariquiey Álvarez (1968), but their taxonomic status will be clarified with ongoing molecular phylogenetics research.

Further modifications are still ongoing in brachyuran systematics, so changes in the Iberian carcinofauna are expected to come in the near future. The improvements on the application of molecular tools and phylogenetic inference methods and the use of larval morphology are expected to bring further changes in the systematics of brachyuran crabs. These will have an impact at several taxonomic levels, from species to superfamilies. For example, preliminary studies carried out by our team on the molecular phylogeny of the Inachidae family, or some genera like Ebalia, Liocarcinus and Pisa, point to the presence of synonymy, the necessity to split some taxa into new species, and the erection of new genera. The validity of some species is currently questioned, such as the case of Calappa tuerkayana (possible synonym of Calappa granulata), Geryon trispinosus (possible synonym of Geryon longipes), Macropodia parva (as synonym of Macropodia rostrata) and Macropodia longipes (as synonym of Macropodia tenuirostris).

Although descriptions of crab species new to science are not expected to occur at a significant rate, an increase on the number of taxa in the Iberian Peninsula will surely result from the human introduction of alien species, as well as the natural expansion of species from West and North Africa and the eastern Mediterranean. Likely candidates to expand the checklist include Pinnotheres pectunculi (presumably present in the Iberian Peninsula as a native species; d’Udekem d’Acoz pers. comm.), Hemigrapsus sanguineus, Portunus sayi and maybe Potamon ibericum (introduced to the Cagne river in southern France between 1975 and 1983 [Noël and Guinot, 1983]). Species of warmer waters will expand their geographic range through “tropicalization” and climate change will favour the expansion of thermophilic species (Verges et al. 2014). Although not all of their predictions have been fulfilled, the likely arrival of alien species was already mentioned by Almaça (1985) and García Raso et al. (1987), and new species are expected to arrive in the near future.