Two new hermit crab species of Diogenes (Crustacea: Decapoda: Diogenidae) from Atlanto-Mediterranean coasts of Iberian Peninsula: Poleward migrants or merely overlooked indigenous species?

Ecology and Evolution. 2022;12:e8844.   | 1 of 23 https://doi.org/10.1002/ece3.8844 www.ecolevol.org Received:18February2022 | Revised:25March2022 | Accepted:1April2022 DOI: 10.1002/ece3.8844 RESEARCH ARTICLE Two new hermit crab species of Diogenes (Crustacea: Decapoda: Diogenidae) from AtlantoMediterranean coasts of Iberian Peninsula: Poleward migrants or merely overlooked indigenous species? Bruno Almón1,2 | Jose A. Cuesta3 | J. Enrique GarcíaRaso4 This is an open access article under the terms of the CreativeCommonsAttribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ©2022TheAuthors.Ecology and Evolution published by John Wiley & Sons Ltd. LSID:zoobank.org:pub:D7B91E16-35FB-4C7D-B893-F57C0A1D6F5A 1Centro Oceanográfico de Vigo, IEOCSIC, Vigo, Spain 2GrupodeEstudodoMedioMariño (GEMM),ACoruña,Spain 3InstitutodeCienciasMarinasde Andalucía,ICMAN-CSIC,Cádiz,Spain 4Facultad de Ciencias, Departamento de BiologíaAnimal,UniversidaddeMálaga, Málaga,Spain Correspondence BrunoAlmón,CentroOceanográficode Vigo,IEO-CSIC,SubidaaRadioFaro,50- 52,36390Vigo,Spain. Email: [email protected] Funding information This research did not receive any specific funding. Open access financing enabled and organized by the Consejo Superior deInvestigacionesCientíficas(CSIC) (GrantNo.CG01)throughtheCRUE-CSIC members 2021 agreement. Abstract A new hermit crab species of the genus Diogenes with reddishorange cheliped, Diogenes erythromanus sp. nov., is described and illustrated based on specimens from theMediterraneancoastsoftheIberianPeninsula,southernSpain.Inaddition,asecondmorphotypeoriginatingfromMauritanianwatersandmorphologicallyveryclose to D. erythromanus sp. nov. is described as a different species, D. arguinensis sp. nov. The new species are here compared to morphologically similar congeners, especially to those inhabiting the same geographical range. Diogenes erythromanus sp. nov. is distinguishable from other Diogenes primarily by the shape and armature of the left cheliped, with a palm slightly higher than long, with a ridge of spines running along the proximal lower margin that continues with a series of spinose rows forming a central band parallel to the upper margin of the palm. The palm in D. arguinensis sp. nov. is longer than high and shows similar proximal ridge, but without central spinose ridge. The shape of the cheliped is also different in D. arguinensis sp. nov., with long dactylus, which is also flattened and twisted. Sequences from two mitochondrial and one nuclear genes, and comparative analyses with other available sequences for the genus,arealsoincluded.Molecularphylogeneticanalysessupportthemorphological delimitation, with D. erythromanus sp. nov. and D. arguinensis sp. nov. forming a separate group, more related to other tropical species, which raises different possible explanationsforitspresenceintheIberianPeninsula. KEYWORDS anomura, biodiversity, biogeography, molecular systematics, species delineation, taxonomy, tropicalization TAXONOMY CLASSIFICATION Biodiversityecology;Biogeography;Communityecology;Ecosystemecology;Movement ecology; Spatial ecology; Taxonomy; Zoology 2 of 23 | ALMÓN et AL. 1 | INTRODUCTION The hermit crab genus DiogenesDana,1851,iscurrentlyrepresented by74speciesworldwide(Almónetal.,2021; Komai & Yoshida, 2020; Lemaitre&McLaughlin,2022),withthenumberofnewspeciesbeing described in continuous increase in recent years, as a consequence of the implementation and generalization of molecular tools, which has allowed to address ancient taxonomic dilemmas and clarify species identities.Mostoftheeffortsmadeinthestudyofthisgenushas beenfocusedonIndo-WestPacificcoasts,withseveralnewspecies describedinthelastthreedecades(Asakura,2006, 2020;Asakura & Godwin, 2006;Asakura&Tachikawa,2010; Igawa & Kato, 2017; Komai et al., 2012, 2013, 2018; Komai & Yoshida, 2020;McLaughlin & Clark, 1997; McLaughlin & Holthuis, 2001; Morgan & Forest, 1991; Rahayu, 1996, 2012, 2015; Rahayu & Forest, 1995; Rahayu & Hortle,2002;Siddiqui&McLaughlin,2003; Trivedi et al., 2016; Xiao et al., 2015).However,thestudyofthediogenidsintheAtlantichad its peak five decades ago and has remained since then scarce and outdated(Almónetal.,2021; Landschoff & Rahayu, 2018). The recent revision and comparison of specimens belonging to the genus Diogenes originating from the coasts of the Iberian Peninsula,andnearbyareas,revealedtheexistenceofaspecies complex so far included in the nominal species Diogenes pugilator (Roux, 1829).Thestudyofthesematerialledtotheredescription of Diogenes pugilator, the resurrection of D. curvimanus (Clément, 1874), an ancient synonym, and the description of D. armatus Almónetal.,2021asanewspecies(Almónetal.,2021),adding twospeciestotheeightalreadyknownfromtheAtlantic.Inthat work, it was stated that several other morphotypes were identified as different and should be addressed in a separate work. Some of them were included in the phylogenetic analysis and the results of the phylogeny showed them as valid species and distinguishable from the rest, but without matching any of species known to date. The present work deals with two of these morphotypes, preliminary labeled as Diogenes sp1 and Diogenes sp2, and has as main objectives:(1)todescribebothmorphotypesasnewspeciesforthegenus, (2)toupdatetheinformationaboutthegenuswithinEuropeanwaters, (3)investigatetheirpossibleoriginandinquirewhethertheirarrivalin Europemightbetheresultofrecentmigrationorotherwise,and(4)to updatetheidentificationkeyfortheAtlanticdiogenidspecies. 2 | MATERIALS AND METHODS Specimens included in this study come from different sources and were obtained during sampling trips conducted during the period 2018– 2020.Additionalsampleswererecoveredfromthecrustaceanreferencecollection“ColeccióndeCrustáceosDecápodosyEstomatópodos delCentroOceanográficodeCádiz(CCDE-IEOCD),”belongingtothe SpanishInstituteofOceanography(IEO-CSIC;Muñoz&García-Isarch, 2021),andfromBiologicalReferenceCollections(CBR)attheInstitutde CiènciesdelMar(ICM-CSIC,Barcelona,Spain;Guerreroetal.,2020),to complete the information about the distribution of these species and to explore the hypothesis of their possible recent arrival to Iberian waters. Allspecimenswerestudiedunderthestereomicroscopeandclassified to the lowest taxonomical level possible. For preventing damage of key structures for morphological identification, a piece of one of the antennae or single ambulatory leg wereusedastissuesampleforDNAextractioninmalesandnon- ovigerous females, while eggs were employed for ovigerous females. Extraction protocol follows that from Estoup et al. (1996)and wascarriedoutattheInstitutodeCienciasMarinasdeAndalucía (ICMAN-CSIC). Partial gene sequences were amplified using the followingPCRthermalcycles:initialdenaturingfor5minat95°C; followedby40cycles:30sat95°C,30sat45–56°C(dependingon primer pairs, see Table 1),45sat72°C;andafinalextensionof3min at72°C.NewspecificCOIprimers(DiogFandDiogR)weredesigned TABLE 1 ListofprimersequencesusedinthisstudyforthePCRamplificationofpartialsequencesof16S,COIand28Sgenes,including paircombined,annealingtemperatureforeachprimerpair(AT),lengthofthesequencesobtained(bp),andreferences Gene Primer Sequence Pair AT (°C) bp Reference 16S 1472 5′-AGATAGAAACCAACCTGG-3′ 16L2 45 570 Crandall and Fitzpatrick (1996) 16L2 5′-TGCCTGTTTATCAAAAACAT-3′ Schubart et al. (2002) 16br 5′-CCGGTCTGAACTCAGATCACGT-3′ 16L12 52 450 Palumbietal.(1991) 16L12 5′-TGACCGTGCAAAGGTAGGATAA-3′ Schubart et al. (1998) COI DiogF 5′-TTGGWGCWTGRGCYGGWATAG-3′ DiogR/COH6 54/54 580/625 Presentstudy DiogR 5′-GGATCYCCWCCWCCWGCHGGA-3′ Presentstudy COH6 5′-TADACTTCDGGRTGDCCAAARAAY C A - 3 ′ COL6b 45 670 SchubartandHuber(2006) COL6b 5′-ACAAATCATAAAGATATYGG-3′ SchubartandHuber(2006) 28S 28L1 5′-CGGAGGAAAAGAAACCAACAG-3′ 28DH2 56 750 MockandSchubart(2021) 28D2H 5′-TGACTCGCACACATGTTAGA-3′ 750 MockandSchubart(2021) | 3 of 23 ALMÓN et AL. forthisstudyduetodifficultiesinobtainingPCRamplificationwith thecommonlyuseduniversalprimers.PCRampliconsforpartialsequences of the 16S, COI, and 28S genes were sent for purification andsequencingtoexternallaboratories(StabVida). Consensus sequences were generated from the complementary sequenceswithBioeditvr.7.0.5(Hall,1999).BLASTsearcheswere performed for each of these sequences in GenBank and for the COI also in BoLD to compare with the available information, confirm or refute the identification, and detect possible issues in these databases. For the phylogenetic approach, 31 of the available sequences belonging to DiogenesweredownloadedfromtheNationalCenterfor BiotechnologyInformation(NCBI)database(Table 2)andassembled alongwiththe153sequencesgeneratedinapreviousstudy(Almón et al., 2021)andthe30newsequencesgeneratedinthisstudy.The finaldatasetwasthenalignedbyMUltipleSequenceComparisonby Log-Expectation(MUSCLE;Edgar,2004),implementedinMEGAX version 10.2 (Kumar et al., 2018). Blocks of ambiguous data in the nonproteincoding gene alignments were identified and excluded using Gblocks with relaxed settings (Talavera & Castresana, 2007).GeneconcatenationoftheCOI+16S (1187bp)andthebest-fittingnucleotidesubstitutionmodelsforeach gene and for the entire alignment were assessed with the tools implementedinMEGAX,usingthecorrectedAkaikeinformationcriterion, asrecommendedbyPosadaandBuckley(2004).Accordingtotheresults of this method, the Tamura 3parameter model of nucleotide substitution using discrete gammadistributed rates for the variable sites and with invariant sites (T92+G+I)wasselectedinallcases.Estimates of evolutionary divergence between sequences were obtained using thepairwisedistancescalculationtoolimplementedinMEGAX. Maximum-likelihood (ML) analyses were conducted for the concatenated dataset, as well as for the individual genes (16S, COI, and28S).Concatenatedanalyseswerepartitionedbasedongene identity(i.e.,16SandCOI).TwospeciesofthefamilyDiogenidae, Dardanus arrosor (Herbst, 1796) and Paguristes eremita (Linnaeus, 1767), were selected as outgroups. ML analyses were performed using MEGA X software under the T92+G+I model. A random startingtreewasgeneratedusingtheNeighbor-Joiningmethod,selectingthepartialdeletionoption(75%sitecoveragecutoff).AML treewasgeneratedusingtheNearest-Neighborinterchangeoption. Topological robustness was investigated using 1000 nonparametric bootstrap replicates. In the resulting trees, only the values >70% nodal support are shown. 3 | RESULTS 3.1 | Systematic account 3.1.1 | FamilyDiogenidaeOrtmann,1892 Genus Diogenes Dana, 1851. Diogenes erythromanus sp. nov. (Figures 1ag, 2ag, 3df, 4d). LSID:zoobank.org:act:50067F29-4086-41C7-8714- DCE0F3FC5326. Holotype: 1♀ 2.8 mm, (IEOCD-BR/2680), Spain: Baños del Carmen,Málaga,36°43'02.4"N,4°23'12.6"W,sand,subtidal,15m, June 14, 2018. Paratypes: 1♀ 3.2 mm, 1♂ 3 . 0  m m  ( I E O - C D - C C L M E 1 2 - 2 5 7 8 –1 ,  2578–2), Morocco: off Kenitra, 34°23'16.8"N, 6°37'27.5"W sand, subtidal, 31 m, July 11, 2012. Other material: Spain: 1♂, 1♀ ( I E O - C D - B R - 2 9 2 1 ,  2 9 3 3 ) ,  C a b o  Pino, Mijas, Málaga, 36⁰29’42’’N, 4⁰39’36’’W fine sand, subtidal, 15 m, September 23, 2009; Morocco: 2♂, 6♀ (IEOCDCCLME12/2578-3),samedataasParatype. Description: Shield (Figure 1a) subquadrate, slightly longer than broad, not vaulted; rostral lobe broadly rounded, exceeded by lateral projections, which are triangular, acutely pointed, with single spine at apex; anterior margins between rostral lobe and lateral projections slightly concave; anterolateral margins sloping, smooth; anterolateral angles rounded, usually with one terminal and one subterminal spines; lateral margins almost straight, with posterior halves each cut by two transverse, spinulose ridges on proximal half, extending onto lateral surface of shield; posterior margin truncate; dorsal surface with additional subtle short transverse rows of small tubercles and tufts of short stiff setae; additionallongitudinalrowof4–5smallspinesadjacenttolateral marginsindistalhalf.Branchiostegiteswithrowof5+ 1 paired +1strongspinesondorsalmargin.Posterolateralplatesnotwell calcified, unarmed. Ocular peduncles (including corneas) about 0.5–0.6 times as long as shield, moderately stout, slightly narrowed medially; corneas not dilated, corneal diameter about 0.3 peduncle length; row of short plumose setae on mesial margin of peduncles. Ocular acicles (Figure 1a,b)subtriangular,withsinuousmesialmargin;anteriormarginslightlyconvex,bearing4–5largeacutedistalspinesand 2–3smallspines(sometimesreducedtosmalltubercles)decreasing in size toward outer margin; innermost 2 distal spines distinctly larger; rest of lateroanterior outer margin smooth, occupying about 1/3 of anterior margin. Intercalary rostriform process simple, slender, slightly shorter than or subequal in length to ocular acicles (excludingspines),taperingtoacutetip. Antennal peduncles (Figure 1a) overreaching distal corneal margin by about 0.8– 0.9 length of ultimate segment, overreaching distal margin of antennal peduncle; third segment unarmed, slightly broadened distally, about 4 times longer than distal width, subequal in length to penultimate segment, with a single setae dorsomedially and subdistal tuft of paired setae; second segment unarmed, with tuft of short setae on dorsodistal margin and second tuft near proximal margin; basal segment unarmed except for dentate ventrodistal outer border, with distal tuft of setae. Antennal peduncles (Figure 1a,c) overreaching distal corneal margin by 0.3– 0.4 length of fifth segment; fifth segment with tufts of long stiff setae on dorsal and ventral outer margins, unarmed; fourth segment with distoouter spine and associate tuft of long setae; tuft of setae on distomesial margin; third segment unarmed; 4 of 23 | ALMÓN et AL. TABLE 2 ListofDNAsequencesofDiogenes included in the present study, including newly generated and retrieved from previous study, alongwiththeselectedsequencesdownloadedfromNCBI/BOLDdatabases,withvouchernumbers,collectionareaandGenBank/BoLD accession codes for 16S, COI, and 28S partial sequences; type specimens are indicated by an asterisk and sequences generated in this study are shown in bold Species Collection location Voucher Gene 16S COI 28S Diogenes curvimanus Spain MNHN-IU−2019–3214* MW791779 MW776663 MW802642 Diogenes curvimanus Spain IEOCD-BR/2581 MW791781 MW776675 - Diogenes curvimanus Spain I E O C D - B R / 2 5 8 2 MW791782 MW776662 MW802643 Diogenes curvimanus Spain ZSMA20190398 MW791784 MW776672 - Diogenes curvimanus Spain I E O C D - B R / 2 5 9 6 MW791785 MW776674 - Diogenes curvimanus Spain I E O C D - B R / 2 5 9 7 MW791786 MW776673 - Diogenes curvimanus Spain I E O C D - B R / 2 5 9 8 MW791792 MW776669 - Diogenes curvimanus Spain I E O C D - B R / 2 5 9 9 MW791788 MW776668 MW802644 Diogenes curvimanus Spain IEOCDBR/2600 MW791789 MW776667 - Diogenes curvimanus Spain IEOCDBR/2601 MW791787 MW776676 - Diogenes curvimanus Spain IEOCDBR/2604 MW791783 - - Diogenes curvimanus Spain I E O C D - B R / 2 6 0 5 MW791790 MW776671 MW802645 Diogenes curvimanus Spain IEOCDBR/2606 MW791791 MW776670 MW802646 Diogenes curvimanus Spain IEOCDBR/2607 MW791777 MW776666 MW802639 Diogenes curvimanus Spain IEOCDBR/2608 MW791778 MW776665 MW802640 Diogenes curvimanus Spain IEOCDBR/2609 MW791780 MW776664 MW802641 Diogenes curvimanus Belgium IEOCDBR/2612 - MW776659 - Diogenes curvimanus Belgium IEOCDBR/2618 - MW776658 MW802648 Diogenes curvimanus Belgium IEOCDBR/2619 - MW776660 - Diogenes curvimanus France IEOCDBR/2621 MW791793 MW776661 MW802647 Diogenes curvimanus Spain IEOCDBR/2622 MW791776 - - Diogenes armatus Spain MNHN-IU−2014–5736* MW791814 MW776705 MW802658 Diogenes armatus Spain MNHN-IU−2019–3213* MW791815 MW776704 MW802659 Diogenes armatus Spain I E O C D - B R / 2 6 4 5 MW791813 MW776701 MW802657 Diogenes armatus Spain ZSMA20190402 MW791806 MW776709 MW802653 Diogenes armatus Spain IEOCDBR/2623 MW791818 MW776700 - Diogenes armatus Spain IEOCDBR/2624 MW791820 MW776695 - Diogenes armatus Spain I E O C D - B R / 2 6 2 5 MW791810 MW776696 - Diogenes armatus France IEOCDBR/2627 - MW776697 MW802661 Diogenes armatus Corsica IEOCDBR/2628 MW791816 MW776699 - Diogenes armatus Spain IEOCDBR/2631 - MW776698 - Diogenes armatus Spain IEOCDBR/2639 - - MW802660 Diogenes armatus Tunisia IEOCDBR/2640 MW791817 - - Diogenes armatus Tunisia IEOCDBR/2641 MW791819 - - Diogenes armatus Spain IEOCDBR/2642 MW791807 MW776708 MW802654 Diogenes armatus Spain IEOCDBR/2643 MW791811 MW776703 MW802656 Diogenes armatus Spain IEOCDBR/2644 MW791812 MW776702 - Diogenes armatus Portugal IEOCDBR/2647 MW791808 MW776707 MW802655 Diogenes armatus Portugal IEOCDBR/2648 MW791809 MW776706 Diogenes pugilator France MNHN-IU−2019–3215* - MW776683 - Diogenes pugilator Tunisia I E O C D - B R / 2 6 5 9 MW791795 - - Diogenes pugilator Spain IEOCDBR/2660 MW791796 MW776692 OM523062 | 5 of 23 ALMÓN et AL. Species Collection location Voucher Gene 16S COI 28S Diogenes pugilator Spain IEOCDBR/2661 MW791797 MW776688 OM523063 Diogenes pugilator France ZSMA20190400 - MW776678 - Diogenes pugilator France ZSMA20190401 - MW776681 - Diogenes pugilator Spain ICMD143/1998a MW791805 MW776686 - Diogenes pugilator Spain ICMD143/1998b - MW776687 - Diogenes pugilator Spain IEOCDBR/2662 MW791801 MW776694 - Diogenes pugilator France IEOCDBR/2664 MW791804 MW776677 - Diogenes pugilator France I E O C D - B R / 2 6 6 5 - MW776684 - Diogenes pugilator France IEOCDBR/2666 - MW776682 - Diogenes pugilator France IEOCDBR/2667 - MW776685 - Diogenes pugilator France IEOCDBR/2668 - MW776680 - Diogenes pugilator France IEOCDBR/2669 - MW776679 - Diogenes pugilator Spain IEOCDBR/2670 MW791802 - - Diogenes pugilator Tunisia IEOCDBR/2673 MW802638 - - Diogenes pugilator Spain IEOCDBR/2674 MW791799 MW776690 - Diogenes pugilator Spain I E O C D - B R / 2 6 7 5 MW791800 MW776689 - Diogenes pugilator France IEOCDBR/2676 - - MW802652 Diogenes pugilator Spain IEOCDBR/2677 MW791798 MW776691 - Diogenes pugilator Spain IEOCDBR/2678 MW791803 MW776693 - Diogenes ovatus Mauritania IEO-CD-CCLME11/1572-1 MW791794 OM523188 Diogenes ovatus Guinea Conakry IEO-CD-CCLME11/1667 - - MW802650 Diogenes ovatus GuineaBissau IEO-CD-CCLME12/2569 OM523035 MW776721 MW802649 Diogenes ovatus GuineaBissau IEO-CD-CCLME12/2571 OM523036 MW776720 MW802651 Diogenes arguinensis sp. nov. Spain IEOCDBR/2682 MW791826 MW776713 OM523064 Diogenes arguinensis sp. nov. Spain IEOCDBR/2683 MW791825 MW776712 - Diogenes arguinensis sp. nov. Spain IEOCDBR/2684 MW791827 MW776718 - Diogenes arguinensis sp. nov. Mauritania IEO-CD-CCLME12/2572* MW791830 MW776715 - Diogenes arguinensis sp. nov. Mauritania IEO-CD-CCLME12/2573 MW791824 - - Diogenes arguinensis sp. nov. Mauritania IEO-CD-CCLME12/2575 MW791831 MW776714 - Diogenes arguinensis sp. nov. Morocco IEO-CD-CCLME12/2576-1 MW791823 MW776719 MW802664 Diogenes arguinensis sp. nov. Morocco IEO-CD-CCLME12/2577-1 MW791829 MW776716 - Diogenes arguinensis sp. nov. Morocco IEO-CD-CCLME11/690-1 OM523037 MW776717 - Diogenes arguinensis sp. nov. Spain IEOCD-BR−2918 OM523038 OM523183 OM523065 Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 1 9 OM523039 - - Diogenes arguinensis sp. nov. Spain IEOCD-BR−2920 OM523040 - - TABLE 2 (Continued) (Continues) 6 of 23 | ALMÓN et AL. Species Collection location Voucher Gene 16S COI 28S Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 2 OM523041 OM523184 OM523066 Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 3 OM523042 - - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 4 OM523043 - - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 5 OM523044 OM523185 - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 6 OM523045 - - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 7 OM523046 OM523186 - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 2 8 OM523047 - - Diogenes arguinensis sp. nov. Spain IEOCD-BR−2929 OM523048 OM523187 - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 3 0 OM523049 - - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 3 1 OM523050 - - Diogenes arguinensis sp. nov. Spain I E O C D - B R − 2 9 3 2 OM523051 - - Diogenes erythromanus sp. nov. Spain I E O C D - B R / 2 6 8 0 * MW791821 MW776710 MW802662 Diogenes erythromanus sp. nov. Morocco IEO-CD-CCLME12/2578-1 MW791822 MW776711 MW802663 Diogenes erythromanus sp. nov. Spain I E O C D - B R − 2 9 2 1 OM523052 Diogenes erythromanus sp. nov. Spain I E O C D - B R − 2 9 3 3 OM523053 Diogenes albimanus SouthAfrica MB-A066353 - MH482073 - Diogenes pugilator NorthSea - - BNSC192-11 - Diogenes pugilator NorthSea,German Bight - - B N S D E 0 8 4 - 1 1 - Diogenes pugilator NorthSea,German Bight - - B N S D E 0 8 6 - 1 1 - Diogenes miles India - - G B C M A 6 7 0 1 - 1 4 - Diogenes alias India - - G B C M A 6 7 0 7 - 1 4 - Diogenes canaliculatus India - - G B C M A 6 7 0 8 - 1 4 - Diogenes dubius India - - G B C M A 6 7 0 9 - 1 4 - Diogenes manaarensis India - - G B C M A 6 7 1 0 - 1 4 - Diogenes merguiensis India - - G B C M A 6 7 1 1 - 1 4 - Diogenes planimanus India - - G B C M A 6 7 1 7 - 1 4 - Diogenes violaceus India - - G B C M A 6 7 1 8 - 1 4 - Diogenes brevirostris SouthAfrica,Western Cape - - H O N S 0 1 7 - 1 9 - Diogenes brevirostris SouthAfrica HVDBC−53 - HVDBC053-11 - Diogenes viridis Vanuatu MNHN-IU−2008–16281 - MDECA648-10 - Diogenes viridis Vanuatu MNHN-IU−2008–16282 - MDECA649-10 - TABLE 2 (Continued) | 7 of 23 ALMÓN et AL. second segment with distolateral outer process stout and acute; smaller but strong spine on distomesial angle; mesial face with 3– 4 conspicuous distal spines, with dense short plumose setae associated with the spines; first segment dentate on outer and inner anterior margins; plumose short setae present on lateral and ventral surfaces. Antennal acicle triangular, almost reaching distal margin of fourth peduncular segment, bearing simple strong terminal spine plus usually 5–6 spines along mesial margin, and tufts of simple setae on both mesial and lateral margins. Antennal flagellum short androbust,twicelengthofshield,reachingbase(male)ordistalpart (female)ofdactylusofleftcheliped,consistingof28–32articleswith paired long ventrolateral setae and shorter setae on dorsal and ventral surfaces. Third maxilliped (Figure 1d)basiswith1–2smallspines;ischium with crista dentata bearing 2 prominent spines at distal half and 2 smaller spines proximally; merus longer than carpus; ischium and merus with rows of long setae on lateral margins; carpus, propodus and dactylus with dense tufts of thick, very long setae in dorsodistal and dorsomedian margin, concealing part of segments; exopod peduncle reaching 1/3 of endopod carpal length, with row of long setae on mesial margin. Male left cheliped (Figures 2a,b,d,e, 3d,e, 4d)muchlargerthan right (Figure 1e).Dactylus about 1.4 times longer than palm measured along upper margin, proximally broadened, slightly arched, ending in large calcareous claw, crossing tip of fixed finger; upper inner and outer margins well defined by row of strong spines; one incomplete row of smaller subacute tubercles running parallel to upper margin, covering proximal 3/4 of dactylus length; outer surface flattened, covered with small evenly distributed obtuse tubercles reaching lower margin; cutting edge sinuous, with row of calcareous teeth of various size, biggest in proximal area; lower margin with tufts of stiff setae; rest of outer surface with some sparse setae associated with tubercles; inner surface smooth and glabrous, except for row of rounded tubercles in medial zone running parallel to upper margin, defining a concave area between them. Fixed finger equilateral triangle shaped, not delimited by a concavity proximoventrally; outer surface covered with evenly distributed small acute tubercles increasing in size distally; cutting edge sinuous, with single row of various sized teeth, biggest medially, and row of spaced tufts of stiff setae below it; proximal area wide, not depressed; lower margin straight, defined buy rows of low rounded tubercles; inner surface without setae and almost smooth. Palm robust, about 1.1 timeshigherthanlong(maximumheight—max.mediallength);upper margin slightly convex, shorter than carpus, defined by row of welldeveloped spines of similar size with associate short setae; upper inner margin defined by row of smaller but strong spines; space between rows slightly widening distally; outer surface medially inflated; upperouterpart(belowrowofspinesonuppermargin)slightlyconcave proximally; rest of palm outer surface with small sharp spines, larger in upper half, larger ones arranged in diffuse longitudinal rows; distinct row of welldeveloped spines starting in proximal lower margin, running obliquely to proximal margin, continuing then with central longitudinal diffuse row of smaller spines decreasing in size distally; lower margin almost straight in outer view, defined by rows of welldeveloped spines increasing in size proximally, where join proximal row; proximoventral area with greater accumulation Species Collection location Voucher Gene 16S COI 28S Diogenes pallescens Vanuatu MNHN-IU−2008–16294 - M D E C A 6 5 8 - 1 0 - Diogenes pallescens Vanuatu MNHN-IU−2008–16297 - MDECA660-10 - Diogenes pugilator Portugal,Alentejo LMBSWB1-001 - M L A L E 0 6 7 - 1 4 - Diogenes pugilator Portugal,Alentejo LMBSWB1-002 - MLALE068-14 - Diogenes pugilator Portugal,Alentejo LMBSWB1-003 - M L A L E 0 6 9 - 1 4 - Diogenes costatus SouthAfrica: KwaZulu-Natal MB-A066693 - MH481985 - Diogenes costatus SouthAfrica:Western Cape MB-A066759 - MH481993 - Diogenes spinicarpus Vanuatu MNHN-IU−2008–16275 - MDECA642-10 - Diogenes spinicarpus Vanuatu MNHN-IU−2008–16276 - MDECA643-10 - Diogenes goniochirus China - MK610031 - - Diogenes edwardsii China - MK610030 - - Diogenes nitidimanus China - MK610029 - - Diogenes rectimanus China - MK610028 - - Diogenes deflectomanus China - MK610027 - - Diogenes avarus China - MK610026 - - Paguristes eremita Morocco IEO-CD-CCLME11/1591 MW791833 MW776657 - Dardanus arrosor Morocco IEO-CD-CCLME11/1575 MW791834 MW776656 - TABLE 2 (Continued) 8 of 23 | ALMÓN et AL. of spines on slightly protruding flat area; lower margin keeled and sinusoidal in ventral view (Figure 3df); inner surface glabrous, slightly inflated medially, concave proximally, covered with poorly developed rounded tubercles, of similar sizes, becoming acute tubercles near upper margin; welldefined smooth concave area adjacent to inner lower margin. Carpus as long as high (Figure 2a,b),1.3 times longer than palm upper margin; upper outer margin defined by row of strong spines increasing in size distally, with row of smaller spines on upper inner margin; outer surface convex, covered with small tubercles becoming spines medially, with sparse short setae; broad shallow concave area present just below upper outer margin, becoming deeper proximally; lower margin defined by row of small spines, biggest subdistal; distoouter anterior border bearing series of small spines submarginally; inner surface covered with sparse low acute tubercles becoming spines mesially, almost glabrous; distal margin dentate, with row of short setae. Merus 1.4 times longer than high (Figure 2a,b,e,g),subtriangularindorsalview;distalmarginwith sparse small spines, largest on ventrolateral area, with row of short simple setae; dorsal surface with row of obtuse spines, increasing in size distally, accompanied with long plumose setae; lateral surface almost smooth except for small spines adjacent to dorsolateral and ventrolateral margins, glabrous; spinose transverse furrow subdistally, with associated short setae; ventrolateral margin denticulate with strong spines, biggest medially, and tufts of plumose setae; proximal half markedly concave, defining a wide depression at ventral area (Figures 2g, 4d);mesialfacewithweaklycalcifiedu-shaped patch, distally divided by deep transverse furrow dorsally bearing small denticulate protuberances (Figure 2e)andtuftsoflongthick setae; distal mesial part divided into dorsal, central and ventral lobes by median clefts; dorsal lobe with distal margin bearing spines of similar size and tufts of mediumsize setae; central lobe small, with distal margin smooth; ventral lobe with ventral margin defined by FIGURE 1 Diogenes erythromanus sp. nov. Málaga, ♀ 2.8 mm, Spain, holotype, (IEOCD-BR/2680):(a)Anteriorpart of carapace and cephalic appendages, dorsalview;(b)ocularaciclesand intercalary rostriform process, dorsal view;(c)rightantennalpeduncle,mesial face;(d)leftmaxiliped3(inset:detailof thespines,ventralaspect);(g)Telson, dorsal view. Diogenes erythromanus sp. nov. Morocco, ♂ 3.0 mm, paratype (IEO-CD-CCLME12/2578-2):(e)right cheliped,outerview;(f)Leftpereiopod2 (insets—variationsinP3carpus;dactylus innerview).(Scales:a,e-g= 1 mm; bc, g =0.5mm) | 9 of 23 ALMÓN et AL. rows of strong spines, and tufts of long plumose setae. Ischium with transverse row of small spines on distolateral margin and row of acute tubercles on ventral margin (Figure 2e). Female left cheliped (Figures 2c, 3e,f)differsfrommaleinthe following features: Palm oval, globose, 1.2 times longer than high; outer surface with more developed tubercles and spines, but arranged in similar way, with welldefined longitudinal rows of spines at middle area and at upper half; lower margin convex throughout, with marginal flat area extending from proximal margin until beginning of fixed finger. Carpus with strong spines on distal upper and lower margin, and longitudinal row of spines medially. Merus with spines of dorsal margin larger than in males; median cleft almost inconspicuous. Right cheliped (Figure 1e)appreciablyshorterthanleft,robust, reaching proximal margin of palm of left; dactylus and fixed finger with narrow hiatus, both terminating in small calcareous claws. Dactylus slightly more than 2.0 times longer than palm (measured alongmesialmargin),gentlyarched;upperinnerandoutermargins defined by rows of spines with associated long abundant setae; outer surface slightly convex, covered with irregular rows of spines in upper half; lower half almost smooth; cutting edge with row of small calcareous teeth, terminating in small calcareous claw and tufts of setae parallel to cutting edge; inner surface smooth except for two rows of tufts of setae parallel to upper margin and cutting edge. Fixed finger not broadened proximally, with rows of welldeveloped spines; inner surface smooth, with tufts of simple setae on palm and two rows of stout setae on fixed finger. Palm upper outer margin defined by a row of spines; outer surface convex, with rows of small spines, obscured by tufts of long setae; lower margin defined by small obtuse subacute tubercles. Carpus widened distally, FIGURE 2 Diogenes erythromanus sp. nov. Morocco, ♂ 3.0 mm, paratype, (IEO-CD-CCLME12/2578-2):(a)Left cheliped,outerview;(b)leftcheliped, dorsalview;(d)leftcheliped,palminner surface;(e)merus,mesialview(seat omitted);(g)merus,outerview.Diogenes erythromanus sp. nov. Málaga, Spain, ♀ 2.8mm,holotype,(IEOCD-BR/2680):(c) Leftcheliped,outerview.(f)pereiopod4. (Scales: a, d = 2 mm; bc, eg =1mm) 16 of 23 | ALMÓN et AL. Maleunpairedleftpleopods2–5present,uniramous,marginally setose. Female with paired gonopores, unpaired 2– 4 pleopods well developed, biramous; fifth pleopods without exopod, as in male. Telson (Figure 5g)slightlyasymmetrical,mediancleftsmalland shallow; left posterior lobe slightly larger than right, with strong terminal spines and with row of slightly smaller spines on lateral margin decreasing in size anteriorly; oblique terminal margin with smaller spines; few additional larger spines along the ventral surface of lateral margin; right posterior lobe with row of small spines on less oblique terminal margin, becoming blunt tubercles on posterior half of lateral margin. Coloration:Unknown.Allavailablespecimenswerepreservedin alcohol. Etymology: The name of the species pays tribute to the area of origin of the specimen on which its description is based, off the Cape Timiris,neartheNationalParkBancD'Arguin,aprotectedareaof singularvalueontheMauritaniancoast,wherethefirstauthorspent several years and of which he keeps a pleasant memory. Habitat: Sandy beaches along shallow subtidal areas, up to 60 m. Distribution: The species has been recollected so far from several Atlanto-Mediterranean localities in the Iberian Peninsula (Málaga: Mijas and Torremolinos; Huelva: Doñana National Park), andfromnorthwesternAfricancoasts(MoroccoandMauritania). Remarks:AsithappensinotherDiogenes species, the shape and size of the left cheliped seems to be highly variable in this species. The main variations observed in the samples analyzed have been summarized in Figure 4 ( f – k ) . Besides the possible variations, the combination of the flattened and curved dactylus and fixed finger in the shape of an isosceles triangle, the outer surface of palm with a concavity defining the inflection change along the base of the fixed finger and running then parallel to the lower margin, the lower margin of palm concave at distal half, and the carpus lower margin without proximal sinus, can be considered persistent for males in all samples, and therefore, representative of the species. Female individuals have shown less variability, with only some differences in the development of spines and tubercles, generally, size related. We acknowledge, as one of the reviewers of this paper also proposed, that the new species shares some similarities with the Diogenes pugilator var. cristata (Balss, 1921)asdescribedbyRossignol(1962),especially at cheliped level. Despite the undoubted similarities found between the chelipeds, the drawings of the cephalothorax included in his workshowsnotabledifferences.Attemptstolocatethespecimens used by Rossignol in his descriptions have been unsuccessful. In addition, it is difficult to form an opinion on the varieties mentioned or described by Balss (1921)becauseofthebrevityofhisdiagnoses and the absence of figures. Forest (1955)mentionedthatunfortunately the types of the new Balss varieties were destroyed during the war, and that the cristata variety is possibly related to D. denticulatus (and the subcristatavarietytoaseparatespecies).Therefore, we do not have enough evidence to decide whether or not it could be the same species, which is why the resurrection of the Rossignol variety has been ruled out, describing this form as a new species. On the other hand, according to Rossignol (1957, 1962),thisvarietycan be easily obtained by diving at shallow depths along the beach of Pointe-Noire,particularlynearthemouthoftheSongoloRiver.Our specimensarefrequentbetween15and25m(rareat5m)inthe areaofCaboPino(Málaga,Spain). 4 | DISCUSSION 4.1 | Taxonomic remarks Diogenes erythromanus sp. nov. and D. arguinensis sp. nov. are referredtothe“edwardsii”group,definedbythepresenceofthesimple intercalary rostriform process, the antennal peduncle distinctly longer than the ocular peduncle, and the presence of paired long setae inserted on the ventral surfaces of articles of the antennal flagellum(Asakura&Tachinawa,2010).TenotherspeciesofDiogenes occurintheEast AtlanticOcean,all ofthemshowingenough diagnostic characters to distinguish them from the species described here. The combination of short and reduced intercalary rostriform process, long ocular peduncles, and the shield bearing strong spines on laterodorsal surfaces, is characteristic of D. mercatoris Forest, 1952, with no other species showing that combination. The intercalary rostriform process is well developed but spinose in D. denticulatus Chevreux & Bouvier, 1981, and D. ortholepis Forest, 1961, while in the species described above, is always smooth. The evident depression on the upper face of the chelar carpus of D. ovatus Miers,1881,allowstoidentifythisspecies,sincenootherAtlantic Diogenes shows similar sculpture in carpus. The serration on the branchiostegite is also different in D. brevirostris Stimpson, 1858, and D. extricatus Stebbing, 1910, with only 2– 3 spines on the posterior branchiostegite, while in D. erythromanus sp. nov. and D. arguinensis sp. nov. they are continuously serrated. The left cheliped of D. costatusHenderson,1893,hasanobliquelylongitudinalridgeon the outer surface and the carpi of the pereiopods bear some scarce spines, never being continuously serrated. Confusion is furthermore unlikely, as D. brevirostris, D. extricatus, and D. costatus have been exclusivelyrecordedfromAtlanticSouthAfricanwaters. Within the socalled “Diogenes pugilatorspeciescomplex,”three other species have been described previously in the same area, although all of them can be easily differentiated from the new ones by the presence in the later of a distoouter spine in antennal peduncle segment four, which is not present in D. pugilator, D. armatus, or D. curvimanus.Additionally,theventrolateraloutermarginof merus of left cheliped in D. erythromanus sp. nov. and D. arguinensis sp. nov. is markedly concave in proximal half and defined by strong spines, while in D. curvimanus, D. armatus, and D. pugilator, this concavity is present but less pronounced, and delimited by tubercles, nor spines (Figure 4a– e).ThemalespecimensofD. curvimanus has also a unique cheliped, which is slender and long, almost without pilosity and with scarcely developed spines, showing in most of the cases only different sizes of rounded tubercles associated with the upper margin of the cheliped. The ocular acicles are continuously | 17 of 23 ALMÓN et AL. serrated in D. armatus, and the male left cheliped outer surface bears strong spines, with abundant pilosity and long setae, while in the species described above the ocular acicles are only partially serrated, the male left cheliped has the outer surface less spinose and the pilosity is sparse and short. The palm of male left cheliped of D. pugilator is globose, with the outer surface markedly inflated and covered by small spinose tubercles, while in the species described here, the palm is not inflated and has spines of different sizesinoutersurface.Moreover,thelowerinnermarginofpalmof left cheliped shows clear differences, allowing to separate the new species from D. pugilator, D. armatus, and D. curvimanus (Figure 3a– i),evenwhentheyareinsidetheshell.Inthenewspecies,thelower margin is keeled and sinusoidal, in ventral view, defined by row of spines, while the other species has several rows of tubercles, defining a more or less extensive flattened tuberculated area, being in D. pugilator also delimited by a sinuous crestlike row of large rounded tubercles. The new species are morphologically very close to each other, being the main diagnostic characters: The general shape of the palm of the left cheliped is slightly higher than long in D. erythromanus sp. nov., while in D. arguinensis sp. nov. is longer than high; the presence in males of D. erythromanus sp. nov. of a flat area with accumulation of spines on proximoventral area of palm, slightly protruding ventrally, is not present in D. arguinensis sp. nov. (this character is even more evident in females, where the flat area extends along most of the lower margin overreaching the base of thefixedfinger);thefingersoftheleftchelipedinD. arguinensis sp. nov. are markedly twisted in dorsal view, the palm outer surface is less tuberculated, and the medial row of spines is shorter than in D. erythromanus sp. nov.; the lower margin of palm of male cheliped is almost straight in D. erythromanus sp. nov., bearing welldeveloped spines, while in D. arguinensis sp. nov. there is always a concave area at lower margin, more or less developed but always evident, bearing also markedly obtuse spines. Differentiation of females can be more challenging, with palm of left cheliped in both species being globose with similar shape. However,thepresenceofaflatareaalongthelowermarginispersistent in all specimens, making the palm of D. erythromanus sp. nov. slightlylessroundedinshape.Moreover,theoutersurfaceismore granulose, with larger tubercles and spines, while in D. arguinensis sp. nov. the appearance is smoother, although it does present tubercles, but these are low and rounded. 4.2 | Phylogenetic analyses We analyzed the phylogenetic relationships among the species of Diogenes to test whether the new species constitute genetically separate units. The concatenated dataset includes 6 of the 10 species distributed in the eastern Atlantic, since molecular information for the other species is still limited and have been included in theindividualgenesdatasetswhenavailable.Maximumlikelihood analyses of the combined (Figure 7)andindividualgenesdatasets (Appendix 1, Figures S1-S3) all yielded similar results, recovering the two putative species as monophyletic units, with relatively long branches and strong nodal supports (Figure 7). Results from individual gene analyses allowed to obtain a general overview of the taxonomic status of the species complex, based on thecomparisonwithsequencesobtainedfromNCBI/BOLDdatabases(Appendix1,FiguresS1,S2andS3).Forthe16Sgene,only 6 sequences were available and none of them correspond to species within the study area, while for nuclear 28S gene, no sequence was availableforspeciesofthisgenus.However,thehighernumberand representatives of species among the partial sequences of the COI gene allowed to obtain an overview of the intrageneric relationships, where the new species are clustered together with D. costatus and D. albimanus,bothspeciesrecordedfromSouthAfricanAtlanticwaters. The analysis shows another three species grouped relatively close to thepreviousones,includingtheIndo-WestPacificD. merguiensis de Man,1888[indeMan,1887–1888]andD. viridisHaig&Ball,1988, along with D. canaliculatusKomai,Reshmi&ABKumar,2013,aspecies with distribution in the Indian ocean and the Red Sea. Genetic intraspecific divergence values were of 0.01 in D. erythromanus sp. nov., ranging between 0.00 and 0.02 within sequences belonging to D. arguinensis sp. nov., with divergence values between the two new species ranging from 0.07 to 0.09. Interspecific distances between the new taxa and other congeneric species ranged from 0.04 to 0.07 for D. costatus, 0.12 to 0.16 for D. albimanus, and from 0.17 to 0.22 for D. pugilator, D. armatus, and D. curvimanus. There are still many gaps regarding molecular information about species of the genus with distributions that could help to explain the intrageneric relations, as well as to better understand the possible migratorydisplacementscarriedoutfromnativeareas.However,theresults from the molecular phylogenies suggest a closest relationship of D. erythromanus sp. nov. and D. arguinensis sp. nov. with species of tropical affinity, rather than those of European temperate waters. Therefore, theDNAevidenceagreeswithseparationsbasedonmorphological characters and confirm the taxonomic delimitation of the species. 4.3 | Biogeographical implications The presence of D. erythromanus sp. nov. and D. arguinensis sp. nov. on both sides of the Strait of Gibraltar, as well as the relationships inferred from the phylogenetic analysis, suggest a closest connectionwithotherAfricancongenericspecies,ratherthanwithother European ones, opening the possibility to different explanations for theirpresenceintheIberianPeninsula. The first hypothesis involves the migration of the species from AfricatoEurope,aprocessknownastropicalization(Cuestaetal., 2016). It is well known that anthropogenic activities and climate change are among the most important factors that may enhance the establishment of introduced species, as well as the poleward shift in distribution of numerous species over decades (GonzálezOrtegónetal.,2020),evenovercomingimportantgeographicbarriersunderfavorableconditions(Pattersonetal.,2022).TheStraitof Gibraltar area has an important role as a pathway of introductions 18 of 23 | ALMÓN et AL. bothfromtheMediterraneanSeaandbyWestAfricanbiotamovingnorthwardsintoEuropeanwaters,thelaterlabeledas“African Creep” byCanning-ClodeandCarlton(2017). The numberofdecapod species that have followed this path in the last decades is significant (e.g., Acantharcus posteli(Forest,1963),Brachynotus atlanticus Forest, 1957, Callinectes pallidus (de Rochebrune, 1883), Cryptosoma cristatumBrullé,1837[inBrullé,1837–1839],Lysmata uncicornis Holthuis & Maurin, 1952, Ogyrides rarispina Holthuis, 1951,Panopeus africanusA.Milne-Edwards,1867,andXaiva mcleayi (Barnard,1947)),andisexpectedthatcontinuestoincreaseinthefuture (Encarnação et al., 2019;García-Raso,1985, 1993;García-Raso & Manjón-Cabeza, 1996; González-Ortegón, García-Raso, et al., 2020;Holthuis,1977;Pozueloetal.,1976). AlthoughD. arguinensis sp. nov. can be found in high numbers in someareasofthesoutheasternIberianPeninsula,whichmaysuggest that the species was already established in the area, the hypothesis of a recent arrival cannot be discarded. The spread of a species well adapted to its new environment can be fast, as it has happened withotherspeciesastheAfricanHermitcrabPagurus mbizi (Forest, 1955) or the African Pea crab Afropinnotheres monodi Manning, 1993,amongothers(García-Rasoetal.,2014;Perez-Migueletal., 2019).Basedontheavailabledata,D. arguinensis sp. nov. may have been present in the area at least since 2009, which would imply a development of large populations in only 13 years, which is not so much time, even if we consider the establishment and reproduction under favorable conditions. FIGURE 7 Maximumlikelihood phylogenetic tree based on the concatenated mitochondrial data set (16S+COI)includingavailableinformation of representatives of the genus Diogenes, using 1000 nonparametric bootstrap replicates.Numbersonthebranches representMLbootstrapvalues; only bootstrap values >70(ML)are included. The species Dardanus arrosor and Paguristes eremita are included as outgroups | 19 of 23 ALMÓN et AL. Another hypothesis suggests a situation like that reported for theWestAfricanFiddlercrabAfruca tangeri(Eydoux,1835),isolated fromAfricanpopulationsatthetimeoftheseparationoftheIberian PeninsulafromtheAfricancontinent,asconfirmedbythefossilrecords (Gibert et al., 2013).Underthisscenario,D. erythromanus sp. nov. and D. arguinensis sp. nov. had always been present in the area, but for different reasons, they have gone unnoticed. The explanation would be straight forward then, agreeing with the circumstance described above, where several species have been overlooked for decades due to the consideration of D. pugilator as a highly variable species that includes all the morphotypes frequently found in European waters, partoftheMediterraneanSeaandnorthwestAfrica. There is no clear evidence about which of them may be correct, but according with our samples, it is evident that the southern coast of Spain seems to represent the northern limit of the current distribution for both species. 4.4 | Updated key to the presently known Atlantic species of Diogenes Dana, 1851 Anupdateoftherecentlypublished“keytothepresentlyknown AtlanticspeciesofDiogenesDana,1851”(Almónetal.,2021)toinclude the new species described above, is proposed. 1 Intercalary rostriform process between ocular acicles reduced. Shield with oblique rows of strongspines(seeForest1952:Figs.1–5,Forest1955:Fig.14,Pl.II,8) D. mercatoris Forest, 1952 1’ Intercalary rostriform process between ocular acicles not reduced. Spines on shield not as above 2 2Intercalary rostriform between ocular acicles process spinose 3 2’ Intercalary rostriform process between ocular acicles smooth 4 3 Ocular peduncles not overreaching base of fifth segment of antennal peduncles. Inner border of antennalacicleconcave(seeForest1955:Fig.13,Pl.II,fig.7) D. denticulatus Chevreux & Bouvier, 1892 3’ Ocular peduncles long, overreaching base of fifth segment of antennal peduncle. Inner border of antennalaciclestraight(seeForest1961:Fig.1–4) D. ortholepis Forest, 1961 4Branchiostegites partially serrated 5 4’ Branchiostegites serrated throughout 6 5 Uppersurfaceofcarpusofleftchelaconvex,withirregularlyarrangedconicaltubercles;nored spotonleftchela.Wideocularacicles(seeBarnard1950:Figs81a,c,d) D. brevirostris Stimpson, 1858a 5’ Uppersurfaceofcarpusofleftchelaflat,withtwoconspicuousrowsoftubercles;oneredspot onoutersurfaceatpropodusbaseofleftchela.Narrowocularacicles(seeBarnard1950: Fig.81h) D. extricatus Stebbing, 1910a 6Palmofleftchelipedoval,depressed;outersurfacewithdepressionatlowerregion.Carpus short,withdeepdepressiononupperface(seeForest1955:Figs15,16;PlII,9) D. ovatusMiers,1881 6’ Palmofleftchelipednotoval.Carpuswithoutdepressiononupperface 7 7Antennalpedunclessegment4withdisto-outerspine.Propodusofeftchelipedwithlower margin keeled and sinusoidal in ventral view, defined by row of spines increasing in size proximally.Merusofleftchelipedwithventrolateralmarginspinose,withproximalhalf markedly concave, defining a deep depression extending into ventral area, where pereiopods canfitin(Figs.1A,5A;3D-I;2A,C,G,4D,Epresentstudy) 8 7’ Antennalpedunclessegment4unarmed.Propodusofleftchelipedwithlowermarginwithmore or less extended flat tuberculated area, not keeled and sinusoidal. Ventrolateral margin of merus of left cheliped straight or weakly concave 9 8Palmofmaleleftchelipedhigherthanlong,withwell-developedspinesonflatareaproximo- ventrally, slightly protruding; outer surface of palm with medial longitudinal row of small spines; dactyl and fixed finger not markedly flattened; lower margin of palm almost straight definedbyrowsofspines.Pereiopods2and3clearlyoverreachingdistalmarginofleft chelipedwhenfullyextended(Fig.2A,Dpresentstudy) D. erythromanus sp. nov. 8’ Palmofmaleleftchelipedlongerthanhigh,withoutprotrudingflatareaproximo-ventrally; outer surface with very short medial row of tubercles; dactyl and fixed finger markedly flattened and twisted; lower margin of palm concave, defined by markedly obtuse spines. Pereiopods2and3equalinlengthorslightlyoverreachingdistalmarginofleftcheliped(Fig. 6A,D,presentstudy) D. arguinensis sp. nov. 9Palmofmaleleftchelipedclearlylongerthanhigh,carpusfrequentlyhigherthanpalm;outer surface of palm finely grained or smooth. Lower margin of carpus of left cheliped long and straightdistally,slightlyconcaveproximally.Antennularpeduncleshorterthanantennal peduncle,ultimatesegmentwideneddistally(Forest&Guinot1956:Fig.3);(Almónetal., 2021Figs.5,6,7C,F) D. curvimanus Clément, 1874 (Continues) 20 of 23 | ALMÓN et AL. 9’ Palmofmaleleftchelipednotclearlylongerthanwide,carpusaboutthesameheightaspalm; outer surface of palm with tubercles or spines, not smooth. Lower margin of carpus of left chelipedconvexatdistalhalf,formingaprominentsinusproximally.Antennularpeduncle subequal or longer than antennal, not markedly widened distally 10 10 Antennularandantennalpedunclessubequalinlength.Ocularaciclessubtriangular,with3–5 distalspines(innermostlarger),restofanterolateraloutermarginwithsmalltuberclesof similar size. Outer surface of left cheliped palm medially inflated, covered with small spinose tubercles; lower inner surface of palm defined by a sinuous crestlike row of large rounded tubercles(Almónetal.,2021Figs.1,2,7A,D) D. pugilator (Roux, 1829) 10’ Antennularpeduncleslongerthanantennalpeduncles.Ocularacicleswithspinesonwhole length of anterolateral margin, or few spines on distal half, without tubercles. Outer surface of left cheliped palm not medially inflated, with at least some larger tubercles or spines defining ridges; lower inner surface of palm not defined by a sinuous crestlike row of large roundedtubercles(Almónetal.,2021Figs.4A) 11 11 Ocular acicles subtriangular with 11– 12 acute spines decreasing in size, innermost larger, covering entire length of anterolateral margin. Outer surface of male left cheliped palm spinose,withlargestspinesforminglongitudinalrows.Leftchelipedhirsute(Almónetal., 2021Figs.3,4,7B,E) D. armatusAlmónetal., 2021 11’ Ocular acicles with few spines restricted to distal half of anterolateral margin. Outer surface of left cheliped palm almost smooth, with short, but prominent oblique granulated proximal ridge.Leftchelipedglabrous(seeBarnard1950:Fig.81e,f;Henderson1893:Pl.39:7,8; Lewinsohn1969:Fig.6) D. costatusHenderson, 1893a The form Diogenessp.namedbyForestin1956isnotincludedhere,asithasnotyetbeenformallydescribedasanewspecies.Nevertheless,the formdescribedbyForestcanbeeasilyseparatedfromtherestoftheAtlanticspeciesbythereducedcorneasandocularpedunclesreachingbehind distal margin of antennal segment 4. Forest also points out the presence of a conspicuous tooth on distoouter upper margin of left cheliped palm. aSpecieswithAtlanticrecordsrestrictedtoSouthAfricanwatersonly. 5 | CONCLUSIONS Studies devoted to the taxonomic revision of the genus Diogenes in theEastern-Atlantichasbeenscarceinthelastdecades,exceptfor therecentstudiesconductedonSouthAfricancoasts(Landschoff & Rahayu, 2018).AfteragoldenperiodofstudiesonAfricancoasts leaded by J. Forest among others in the mid19th to 20th centuries (see Barnard, 1950, 1955; Chevreux & Bouvier, 1892; Forest, 1952, 1961; Kensley, 1981),wheremostofthecurrentacceptedspecies were described, the account of Diogenes species occurring in this vast area has remained almost inalterable, in part due to the consideration of D. pugilator as a widespread species with high morphological variability (Forest, 1955;McLaughlinetal.,2010). In a previous work, the examination of the variability of Diogenes speciesinhabitingarelativelysmallareaastheIberianPeninsula showed that there were in fact several different species formally assigned to D. pugilator, leading to the description of a new species (D. armatus),theresurrectionofanancientsynonymy(D. curvimanus) and the redescription of D. pugilator sensu Roux, 1829(Almónetal., 2021).Theredescriptionoftheoriginalspecies,aswellasthedesignation of neotypes that allow comparison with other specimens, marks a reference point that did not exist until that moment (since thespecimensdepositedbyRouxseemtohavebeenlost),thusproviding a stable reference from which to build future studies. The application of an integrative taxonomy approach provides a great opportunity to tackle many ancient conflicts from a new and comprehensive perspective. The species described here also belong to the socalled D. pugilator species complex and adds two new species forthegenusandfortheIberianPeninsulacarcinofauna.Basedon the current knowledge about their distribution, their geographical originisnotclear.Althoughtheyarepresentinthesouthernpart oftheIberianPeninsula,themolecularresultssuggestacloserrelationshipwithotherAfricanspeciesthanwithEuropeanones,which opens the possibility of a recent arrival to Europe from northern Africancoasts,wheretheyarealsopresent.Futurestudieswillcontribute to clarify the actual distribution range of the new species, probably revealing along the way, new species still to be discovered. The revision of the Diogenes species present along European andAfricancoastsisapendingsubjectthatwillrequirecooperative work to overreach the great task that imply the study of this vast and complex area, but at the same time it represents an interesting challenge that will probably yield discoveries that will drastically change the composition and general knowledge about the genus as a whole. ACKNOWLEDGMENTS We thank the CBR staff, especially to Pere Abelló and Elena Guerrero for their help in providing specimens for study. This work wouldnothavebeenpossiblewithoutthehelpofEvaGarcía-Isarch andIsabelMuñozfromCentroOceanográficodeCádiz(IEO-CSIC) for providing crucially important specimens, and to Carlos Sánchez (ICMAN-CSIC)forhishelplaboratorywork.Wealsothankthetwo anonymous reviewers and the editor for their valuable suggestions. The authors also declare that all materials have been collected under appropriate collection permits and approved ethics guidelines. TheseresultsarepartofthePhDthesisofthefirstauthor. | 21 of 23 ALMÓN et AL. CONFLICTS OF INTEREST The authors declare no conflicts of interest. AUTHOR CONTRIBUTION Bruno Almón:Conceptualization(equal),datacuration(equal),formalanalysis(lead),fundingacquisition(equal),investigation(equal), methodology (equal), project administration (equal), resources (equal), software (equal), validation (equal), visualization (equal), writing—original draft (lead), writing—review and editing (equal). Jose A. Cuesta:Conceptualization(equal),datacuration(equal),formalanalysis(equal),fundingacquisition(lead),investigation(equal), methodology (equal), project administration (equal), resources (equal),software(equal),supervision(lead),validation(equal),visualization (lead), writing—original draft (equal), writing—review and editing (equal). J. Enrique GarcíaRaso: Conceptualization (equal), data curation (equal), formal analysis (equal), funding acquisition (lead), investigation (equal), methodology (equal), project administration(equal),resources(lead),software(equal),supervision(lead), validation(equal),visualization(equal),writing—originaldraft(equal), writing—reviewandediting(equal). DATA AVAILABILITY STATEMENT The data underlying this article are available in the article and in its onlinesupplementarymaterial.DNAsequencesandrelateddataare publiclyavailableontheNationalCenterforBiotechnologypublic databases (https://www.ncbi.nlm.nih.gov/). The data associated with each of the specimens examined are included in the text, in the appropriatesections.Accessionnumberforsequencesdownloaded from public databases is included in Table 2, along with those generated for this project. ORCID Bruno Almón https://orcid.org/0000-0001-7350-6035 Jose A. Cuesta https://orcid.org/0000-0001-9482-2336 J. 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