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On the family Caridionidae fam. nov., with the description of a new species from the Mediterranean Sea (Crustacea: Decapoda)

Published online by Cambridge University Press:  03 November 2026

Hossein Ashrafi ,
Pierre Chevaldonné  and
Sammy De Grave Open the ORCID record for Sammy De Grave [Opens in a new window]
Hossein Ashrafi
Affiliation:
Biology and Ecology, University of Ostrava, Ostrava, Czech Republic
Pierre Chevaldonné
Affiliation:
IMBE, CNRS, Aix Marseille Université, IRD, Avignon Université, Station Marine d’Endoume, Marseille, France
Sammy De Grave*
Affiliation:
Museum of Natural History, University of Oxford, Oxford, UK
*
Corresponding author: Sammy De Grave; Email: sammy.degrave@oum.ox.ac.uk
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Abstract

The hippolytoid shrimp genus Caridion has long had an uncertain systematic position and traditionally has been assigned to Hippolytidae despite the currently perceived non-monophyly of that family. Until now, the genus included two recognised species, C. gordoni and C. steveni, both known from North Atlantic waters, whereas several larval and adult records from the Mediterranean Sea have remained taxonomically unresolved. Here, we describe a new species of Caridion from the western Mediterranean. The new species differs from its congeners by the shape and dentition of the rostrum, the relative length of the third maxilliped, the gill formula, the colour pattern, and its cave-associated ecology. Based on a phylogenetic analysis of four gene fragments, Caridion is recovered outside Hippolytidae and Thoridae, and a new monotypic family, Caridionidae, is established to accommodate the genus. Although uncommon, Caridion epitelum sp. nov. appears to be widespread at least in the western Mediterranean. It has remained undescribed to date because of its cryptic habitat, general taxonomic confusion in the genus and potentially its general resemblance, at least in situ, to common Mediterranean cave-dwelling shrimp, such as Lysmata nilita.

Keywords

CaridionHippolytidaemolecular phylogenynew speciessubmarine caves

Information

Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 106 , 2026 , e69
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2026. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom.

Introduction

The hippolytoid shrimp genus Caridion Goës, Reference Goës1864 currently comprises two known species, C. gordoni (Spence Bate, Reference Spence Bate1858) and C. steveni Lebour, Reference Lebour1930, both of which are restricted to North Atlantic and Mediterranean waters. Caridion gordoni occurs from Iceland (Lebour, Reference Lebour1930) and the Faroe Islands (Brattegard and Rømer, Reference Brattegard and Rømer1998) southwards to the Galicia Bank in northwestern Spain (Cartes et al., Reference Cartes, Papiol, Frutos, Macpherson, González-pola and Punzón2014). It has been recorded from Norway, Sweden, around the British Isles (more frequent in northern waters) and Ireland (Kemp, Reference Kemp1910a; Ō Céidigh, Reference Ō Céidigh1963), as well as the Bay of Biscay (Kemp, Reference Kemp1910b). In the western Atlantic, the species is known from Newfoundland to Chesapeake Bay (Smith, Reference Smith1879; Squires, Reference Squires1990). The species has been recorded from 10 to 1000 m (d’Udekem d’Acoz, Reference D’udekem D’acoz1999), although more often encountered in deeper water, with some of the shallower records very likely referring to the poorly known C. steveni (see Smaldon et al., Reference Smaldon, Holthuis and Fransen1993). For example, the records from 8 to 10 m deep cobble grounds in southern Ireland by Robinson and Tully (Reference Robinson and Tully2000) and in a rockpool in western Portugal by Vinagre et al. (Reference Vinagre, Dias, Fonseca, Pinto, Cabral and Silva2015) likely are C. steveni, especially as larvae of that species occur in Portugal (see Paula, Reference Paula1987). Often encountered on stony or sandy bottoms, C. gordoni has been considered to be a facultative symbiont of Paragorgia arborea and Lophelia pertusa (see Buhl-Mortensen and Mortensen, Reference Buhl-Mortensen and Mortensen2004), and also has been collected from the oscula of Stryphurus ponderosus in the Faroes (Klitgaard, Reference Klitgaard1995). For a discussion of the complicated nomenclature history of this taxon, see De Grave and Boyko (Reference De Grave and Boyko2024).

The closely related species, C. steveni (Lebour, Reference Lebour1930) is broadly distributed in the same general region, but restricted to the eastern Atlantic (d’Udekem d’Acoz, Reference D’udekem D’acoz1999). Records are scarce and extend from the Faroe Islands (Brattegard and Rømer, Reference Brattegard and Rømer1998) and Sweden (Cedhagen and Hansson, Reference Cedhagen and Hansson1995; Berggren et al., Reference Berggren, Nyman and Pleijel2025) southwards to Brittany (France), including most coasts of the British Isles and Ireland (Ō Céidigh, Reference Ō Céidigh1963; Smaldon et al., Reference Smaldon, Holthuis and Fransen1993), with larval records only from La Manche (Martin, Reference Martin2004). The species is usually collected under stones and cobbles, from the intertidal zone down to 40 m depth (d’Udekem d’Acoz, Reference D’udekem D’acoz1999).

A number of records of the genus are known from the Mediterranean, both as larvae and as adults; the status of most of which is relatively unclear. Kurian (Reference Kurian1956) was the first to record C. steveni larvae from the Adriatic Sea. This record was later repeated by Števčič (Reference Števčič1969) as C. steveni and Števčič (Reference Števčič1990) as C. steveni. A few years later, Bourdillon-Casanova (Reference Bourdillon-Casanova1960) recorded larvae under the same name from the Gulf of Marseille and again recorded by Vives (Reference Vives1966) from the Castellón area (NE Spain) and by Barnich (Reference Barnich1996) from Villefranche-sur-Mer. Torres et al. (Reference Torres, Dos Santos, Balbín, Alemany, Massutí and Reglero2014) recorded a single larval specimen, as C. steveni, from the Balearic Sea. Taken together, these records indicate the taxon in question to be relatively widespread in the Mediterranean, if scarce. Larvae of C. gordoni have also been recorded from the Mediterranean. Bourdillon-Casanova (Reference Bourdillon-Casanova1960) recorded them as rare in the Gulf of Marseille, whilst Seridji (Reference Seridji1971) recorded them from the Bay of Algiers (further listed in Grimes et al., Reference Grimes, Bakalem and Dauvin2016 without information). It remains unclear if indeed two species of Caridion might be present in the Mediterranean Sea, and which ones.

The first adult specimens of the genus from Mediterranean waters were recorded by Ledoyer (Reference Ledoyer1968, as C. steveni), who collected approximately 15 adults at night in a cave in Villefranche-sur-Mer, along the French Mediterranean coast. García and Gracia (Reference García and Gracia1996) recorded a single adult male from Mallorca at 54 m depth, under the name Caridion sp., considering it to be conspecific with the material from Ledoyer (Reference Ledoyer1968), but an undescribed species, agreed upon as such by d’Udekem d’Acoz (Reference D’udekem D’acoz1999). More recently, Abelló et al. (Reference Abelló, Carbonell and Torres2002) obtained a single specimen of C. steveni from off the Ebro Delta (Spain); it is unclear if this is the same taxon, as the specimen was obtained by trawling at 97 m depth. Chevaldonné et al. (Reference Chevaldonné, Sket, Marschal, Lejeusne and Calado2008) indicated that significant numbers of Caridion sp. had been collected from marine caves in Marseille (France) and Monaco, at depths of 15–40 m, presumably the same taxon as originally discovered by Ledoyer (Reference Ledoyer1968). This record was repeated in the review by Bianchi et al. (Reference Bianchi, Gerovasileiou, Morri and Froglia2022), who considered this to be an undescribed species.

Due to the rarity of the genus and the lack of sequence-quality material, the phylogenetic position of Caridion has, to date, not been fully investigated, and the genus was not included in the analysis of De Grave et al. (Reference De Grave, Li, Tsang, Chu and Chan2014). It remains, however, clear that Hippolytidae remains a non-monophyletic assemblage (see discussion in De Grave et al. Reference De Grave, Li, Tsang, Chu and Chan2014). Indeed, recently, Anker and Fransen (Reference Anker and Fransen2026) made a new, monotypic family for the morphologically aberrant genus Leontocaris Stebbing, 1905, and further families are expected to be recognised soon.

Here, we report on recently collected material of a species of Caridion from a marine cave of the Calanques coast near Marseille in 2025 and two specimens from harbour caissons (artificial cave habitats) in Monaco. We confirm its status as an undescribed species and provide a formal description. In addition, we present a phylogenetic analysis that supports the establishment of a new family of caridean shrimps.

Material and methods

For the phylogenetic analysis, we used 41 species belonging to 23 genera from Hippolytidae and several closely related families as the ingroup, and 4 alpheid genera as outgroups. Most species included in the dataset had been sequenced and used in previous studies. Herein, we added two species belonging to the genera Caridion and Eualus, as well as several newly sequenced partial gene fragments, to make the dataset more complete. The specimens used in this study are deposited in the collections of the Muséum National d’Histoire Naturelle, Paris, France (MNHN). Detailed information on the samples and their GenBank accession numbers is provided in Table 1.

Table 1.

Species included in the phylogenetic analysis, with GenBank accession numbers for partial fragments of the four genes 16S, COI, H3, and Enolase, and corresponding references

GenBank accession numbers are listed for 39 shrimp taxa across genes 16S, COI, H3, and Enolase, with many rows showing missing entries for one or more genes. See long description.
Table 1 Long description

Species names are listed in the first column, followed by GenBank accession numbers under four gene columns labeled 16S, COI, H3, and Enolase, plus a Reference column. Several taxa have accession numbers in all four gene columns, including Aretopsis sandybrucei, Automate arturi, Caridion epitelum sp. nov., Eualus sp., Lysmata kuekenthali, Prionalpheus triarticulatus, and the four Thor species listed. Some rows include only two gene entries, such as Bathyhippolyte yaldwyni, Bythocaris leucopis, Gelastocaris paronae, Heptacarpus futilirostris, Heptacarpus sitchensis, and Hippolyte ventricose, each with 16S and Enolase but no COI or H3. Some rows include only COI and H3, such as Heptacarpus rectirostris and Spirontocaris spinus, and some include only COI, such as Gelastreutes crosnieri. Several taxa list three genes but not Enolase, including Hippolyte varians, Hippolyte williamsi, Latreutes parvulus, Lebbeus polaris, and Saron marmoratus. Tozeuma lanceolatum lists 16S and COI only, while Tozeuma sp. lists 16S, COI, and H3 but no Enolase. The Reference column provides one or more citations for each row.

For the newly sequenced specimens, DNA extraction, amplification, primers, and thermocycling conditions followed Ashrafi and Baeza (Reference Ashrafi and Baeza2025). As a result, we obtained partial fragments of 16S, COI, Enolase, and H3, with final alignment lengths of 515, 623, 368, and 326 bp, respectively.

Phylogenetic trees were constructed based on a concatenated dataset comprising four gene fragments: 16S, COI, H3, and Enolase. Sequences of each gene fragment were aligned using MUSCLE (Edgar, Reference Edgar2004), implemented in MEGA ver. 10.1.7 (Kumar et al., Reference Kumar, Stecher, Li, Knyaz and Tamura2018). For the protein-coding genes COI, H3, and Enolase, sequences were translated into amino acids to check for stop codons.

Saturation levels were assessed for each codon position using DAMBE ver. 7.2.102 (Xia and Xie, Reference Xia and Xie2001). Our analyses confirmed that all codon positions of Enolase and H3 were phylogenetically informative and were therefore retained for subsequent analyses. However, the third codon position of COI was found to be substantially saturated; consequently, only the first and second codon positions of COI were retained for further analyses.

The 16S alignment was examined for highly variable positions using Gblocks ver. 0.91.1b (Castresana, Reference Castresana2000), available through the NGPhylogeny.fr platform. Default parameters were used, except that the minimum block length was set to 5 and gap positions were allowed ‘with half’. As a result, 75% of the original 16S alignment, corresponding to 387 of 515 positions, was retained for further analysis.

The final alignments were concatenated using SequenceMatrix ver. 1.7.8 (Vaidya et al., Reference Vaidya, Lohman and Meier2011). PartitionFinder ver. 2.1.1 was then used to determine the best-fit model of nucleotide substitution for each partition in the concatenated dataset, based on the Akaike Information Criterion. Each codon position of the protein-coding genes was assessed separately for its most appropriate nucleotide substitution model (Table 2).

Table 2.

Partition scheme, best-fit substitution models, and number of nucleotide positions used for phylogenetic tree reconstruction

GTR plus I plus G is the best model for subsets 1, 3, and 6, covering 387, 208, and 230 sites across partitions 16S, COI_pos2, and H3_pos3 with Enol_pos3. See long description.
Table 2 Long description

Partition subsets are listed with their best model, number of sites, and partition names. Subset 1 lists best model, GTR plus I plus G, with 387 sites for partition name, 16S. Subset 2 lists best model, SYM plus G, with 208 sites for partition name, COI_pos1. Subset 3 lists best model, GTR plus I plus G, with 208 sites for partition name, COI_pos2. Subset 5 lists best model, K80 plus I plus G, with 355 sites for partition names, H3_pos1, Enol_pos1, and Enol_pos2. Subset 6 lists best model, GTR plus I plus G, with 230 sites for partition names, H3_pos3 and Enol_pos3. Subset 7 lists best model, JC plus I, with 109 sites for partition name, H3_pos2.

Maximum Likelihood analysis was performed using the IQ-TREE web server, with nodal support assessed using the ultrafast bootstrap option with 10,000 replicates. Bayesian Inference (BI) analysis was conducted using MrBayes ver. 3.2.7 (Ronquist et al., Reference Ronquist, Teslenko, van der Mark, Ayres, Darling, Höhna, Larget, Liu, Suchard and Huelsenbeck2012). The Markov Chain Monte Carlo analyses comprised two independent runs, each with four chains, for a total of 30 × 106 generations, with sampling every 1000 generations. The initial 25% of trees were discarded as burn-in, and the remaining trees were used to construct the final consensus tree and estimate Bayesian posterior probabilities. The resulting trees from both analyses were visualised using the iTOL web server (Letunic and Bork, Reference Letunic and Bork2021).

Results and discussion

Order Decapoda Latreille, 1802

Infraorder Caridea Dana, 1852

Caridionidae fam. nov

Diagnosis

Carapace with well-developed rostrum, armed with both dorsal and ventral teeth, ventral margin with moderately developed blade. Antennal tooth present, hepatic and branchiostegal teeth absent. Third pleonite without mid-dorsal hump. Fifth and sixth pleuron with posteroventral margin produced into sharp tooth. Telson with two pairs of dorsolateral cuspidate setae; posterior margin produced, with three pairs of stout spiniform setae. Eyes pigmented, cornea globular, nebenauge absent. Second to fourth thoracic sternites each with pair of median teeth separated by deep cleft; fifth thoracic sternite with pair of subrounded median processes separated by shallow cleft. Stylocerite well-developed, elongate triangular. Third maxilliped extremely elongate, reaching to distal margin of scaphocerite or beyond, dactyl-propodal articulation distinct, exopod present. First pereiopods chelate, equal in shape and size; carpo-propodal grooming brush present; chelae mesially excavated, tips simple. Second pereiopods chelate, equal in shape and size; carpus subdivided into 2 subarticles each side. Third to fifth pereiopods slender, propodi undivided; dactyli biunguiculate. Male first pleopod lacking appendix interna, second pleopod with appendix masculina and interna. Uropods with lateral margin non-serrate. Gill formula: 5 pleurobranchs (above P1–P5); 0 arthrobranch; 0 podobranchs; 2 epipods (Mxp1, Mxp2); 4–5 mastigobranchs (Mxp 3, P1–P3/4); 4–5 sets of setobranchs (P1–4/5); 3 exopods (Mxp 1–3).

Type genus – Caridion Goës, Reference Goës1864

Genera included – monotypic.

Remarks

Our phylogenetic analysis (Figure 1) recovered Caridion, and thus Caridionidae fam. nov., as sister to a clade comprising Bathyhippolyte (Hayashi & Miyake, 1970) and Bythocaris (G. O. Sars, 1870), both currently assigned to Bythocarididae (Christoffersen, Reference Christoffersen1987). This placement outside the clade containing Hippolytidae and Thoridae Kingsley (1878) demands the recognition of a new family. However, the sister-group relationship between Caridionidae fam. nov. and Bythocarididae was not supported in either the Maximum Likelihood or BI analyses. This lack of support may be attributable to two factors: first, only one partial gene sequence, COI, is available for Caridion gordoni, and only two partial gene sequences, 16S and Enolase, are available for the sampled representatives of Bythocarididae; and second, only two representatives of Bythocarididae were included in the present study. Therefore, although the distinct phylogenetic position of Caridion supports the establishment of a new family, its precise relationships within the broader hippolytoid assemblage remain uncertain.

Figure 1.

Phylogenetic tree reconstructed from concatenated partial fragments of four genes, 16S, COI, H3, and Enolase (ENO1), using Maximum Likelihood and Bayesian Inference analyses for Hippolytidae and related families. Each terminal is labelled with the corresponding species name; GenBank accession numbers are provided in Table 1. Bayesian posterior probabilities and bootstrap support values are shown above and below branches, respectively.

Phylogenetic tree showing relationships among shrimp families using gene sequences. See long description.
Figure 1 Long description

A phylogenetic tree illustrates the evolutionary relationships among various shrimp families based on concatenated partial fragments of four genes. The tree is oriented vertically, with branches extending from top to bottom. Each terminal node is labeled with the corresponding species name. Bayesian posterior probabilities and bootstrap support values are displayed above and below the branches, respectively. The tree includes families such as Alpheidae, Merguidae, Lysmatidae, Barbouriidae, Caridionidae, Bythocarididae, Hippolytidae and Thoridae. Caridionidae is shown as sister to a clade comprising Bathyhippolyte and Bythocaris, both assigned to Bythocarididae. The tree scale is indicated at the bottom left.

Lebour (Reference Lebour1930), based on larval characteristics, already stated that the genus possibly should occupy a separate family, closely related to Processidae Ortmann (1896) near both Hippolytidae (Spence Bate, 1888) and Pandalidae (Haworth, 1825); a phylogenetically untenable position (see Bracken et al., Reference Bracken, De Grave, Felder, Martin, Felder and Crandall2009). Christoffersen (Reference Christoffersen1987) on the basis of a morpho-cladistic analysis included the genus in his new family Alopidae, together with Alope (White, 1847) and Chorismus (Spence Bate, 1888). De Grave et al. (Reference De Grave, Li, Tsang, Chu and Chan2014) as well as the present analysis (Figure 1), however, found Chorismus deeply embedded in Hippolytidae sensu stricto. Any perceived similarities between the three genera thus appear superficial, and the family Caridionidae fam. nov. is considered to be monotypic.

Morphologically, Caridionidae fam. nov. can be readily distinguished from the other currently recognised hippolytoid families (De Grave et al., Reference De Grave, Li, Tsang, Chu and Chan2014) by the combination of an extremely elongate third maxilliped, reaching at least to the distal margin of the scaphocerite, the distinct propod-dactylar articulation thereof and the mesially excavated chelae of the first pereiopods, the latter resembling the condition seen in Alvinocarididae, a phylogenetically unrelated caridean family.

Caridion epitelum sp. nov

Figures 2–7

Figure 2.

Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241, live colouration: (a) Dorsal view; (b) lateral view.

Two views of a shrimp: dorsal view (A) and lateral view (B).
Figure 3.

Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Frontal region, dorsal view; (b) same, lateral view; (c) anterior carapace and rostrum, lateral view; (d) proximal portion of antennule, ventral view; (e), posterior four thoracic sternites, ventral view; (f) posterior carapace and pleon, lateral view; (g) anterior four pleonites, ventral view; (h) sixth pleonite, posteroventral view; (i) telson and uropods.

Shrimp anatomical features, including frontal, lateral and ventral views, with detailed sections of carapace, pleon, antennule and telson.
Figure 4.

Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Mandible; (b) maxillule; (c) maxilla; (d) first maxilliped; (e) second maxilliped; (f) third maxilliped; (g) same, distal portion of ultimate article, showing propodus and dactylus.

Various anatomical parts of a crustacean, labeled A to G, with scale bars indicating size.
Figure 5.

Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) First pereiopod, lateral view; (b) same, mesial view; (c) chela of first pereiopod, lateral view; (d) same, fingers, mesial view; (e) second pereiopod, lateral view; (f) same, fingers, mesial view.

Pereiopods and chelae in lateral and mesial views, showing detailed anatomical features.
Figure 6.

Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Third pereiopod, lateral view; (b) fourth pereiopod, lateral view; (c) same, distal portion of propodus and dactylus, mesial view; (d) fifth pereiopod, lateral view; (e) first pleopod; (f) second pleopod.

Pereiopods and pleopods of a crustacean, showing detailed views of appendages labeled A to F.
Figure 7.

Caridion epitelum sp. nov., in situ (specimen not collected), caisson C3, counter breakwater, Port Hercule, Monaco, 35 m; 06.12.2011; photo by T. Pérez.

A micrograph shows a brown background with a central red elongated structure (commonly known as a shrimp) and scattered small debris.

[urn:lsid:zoobank.org:pub:139BEE75-9E27-482B-B8DE-48C26DA773BE]

Caridion steveni – Ledoyer, Reference Ledoyer1968: 225, pl. 11 – Ledoyer, Reference Ledoyer1969: 341 – García Raso, Reference García Raso1987: 115.

Caridion sp. – García & Gracia, Reference García and Gracia1996: 179, Figure 1 – Chevaldonné et al., Reference Chevaldonné, Sket, Marschal, Lejeusne and Calado2008: 187, Table 1 – Bianchi et al., Reference Bianchi, Gerovasileiou, Morri and Froglia2022: 7, Table 1.

Type material

Holotype: male (cl 8.7 mm), MNHN-IU-2022-5241, Figuier marine cave Cap Morgiou, Calanques National Park, near Marseille, France, 43.204837ºN 5.447677ºE

stn. DER49, 15 m, 25.06.2025, coll. P. Chevaldonné.

Paratypes: 1 male (8.3 mm), MNHN-IU-2024-2837, caisson C1, counter breakwater, Port Hercule, Monaco, 15–20 m, 30.11.2010, coll. P. Chevaldonné; 1 male (4.5 mm), MNHN-IU-2024-2838, caisson C3, counter breakwater, Port Hercule, Monaco, 35 m; 06.12.2011, coll. P. Chevaldonné.

Description

Moderately sized caridean shrimp with slender body (Figure 2). Rostrum (Figure 3a–c) slender, straight, slightly overreaching scaphocerite, with rostral tooth formula 2 + 3/2; dorsal teeth occupying proximal two-thirds, distal third unarmed dorsally; ventral teeth positioned approximately at mid-length and on distal third; ventral margin sinuous, ventral blade broadest at mid-length. Carapace (Figure 3a–c) smooth; inferior orbital process protruding, blunt; antennal spine acute; pterygostomial angle rounded.

Second to fourth thoracic sternites (Figure 3e) each with pair of median teeth separated by deep cleft; fifth thoracic sternite with pair of subrounded median processes separated by shallow cleft.

Pleon (Figure 3f, h) with first to third pleura rounded antero- and posteroventrally; third pleonite curved dorsally, imparting general hippolytid form to pleon; fourth and fifth pleura each with small acute tooth posteroventrally; sixth pleuron with triangular projections flanking lateral sides of telson, posteroventral margin without articulated flap.

First to third pleonites (Figure 3g) with posterior margin each armed with pair of small median teeth; fourth pleonite with single tooth on posterior ridge.

Telson (Figure 3i) narrow, approximately 3.6 times as long as proximal width; proximal width 2.5 times distal width; dorsal surface armed with two pairs of slender spiniform setae located at approximately 0.4 and 0.7 of telson length; posterior margin broadly triangular, produced into acute median process, armed with three pairs of slender spiniform setae; lateral pair shortest, about 0.7 times as long as dorsal spiniform setae; intermediate pair longest, about four times as long as dorsal spiniform setae; mesial pair about 0.6 times as long as intermediate pair.

Antennule (Figure 3a, b, d) with peduncle narrow and slender; first article slender, almost four times as long as distal width, without ventromesial spine; stylocerite rather slender, slightly overreaching distal margin of first antennular article; second antennular article 1.7 times as long as broad, about 0.4 times as long as first article; third antennular article slightly longer than broad, slightly shorter than second antennular article; lateral antennular flagellum without clear division into rami, aesthetascs beginning at distal margin of sixth or seventh subarticle, with approximately 20 groups of aesthetascs.

Antenna (Figure 3a, b) with scaphocerite distinctly overreaching antennular peduncle; lateral margin straight; anterolateral tooth well developed, not reaching distal margin of blade; blade broad; basicerite with inferior tooth acute, slightly overreaching anterior margin of cornea, superior tooth slightly projecting; carpocerite relatively slender, reaching approximately to distal margin of second antennular article; flagellum slender.

Eyes (Figures 2 and 3a, b) large, pigmented, cornea globular, nebenauge absent.

Mandible (Figure 4a) with molar and incisor processes of approximately equal size; molar process with five distal teeth, lateral teeth slightly stronger than median teeth; palp well developed, three-segmented, reaching to distal margin of incisor process. Maxillule (Figure 4b) with bilobed palp; dorsal lobe slightly overreaching ventral lobe and armed distally with three setae; ventral lobe slightly stronger than dorsal lobe and armed distally with single long spiniform setae; dorsal endite broadest at mid-length, narrowing towards both ends; ventral endite narrower than dorsal endite, slightly tapering distally. Maxilla (Figure 4c) with broad scaphognathite; dorsal palp simple, with three setae at tip; dorsal endite, or basal endite, bilobed, cleft between two lobes deep, lobes subequal in length, dorsal lobe slightly stronger than ventral lobe; ventral endite, or coxal endite, reduced. First maxilliped (Figure 4d) with shallow, broad cleft between dorsal and ventral endites; exopodite well developed, with caridean lobe distinct; palp narrow, slightly tapering distally, furnished with several setae at tip; epipod broad, bilobed. Second maxilliped (Figure 4e) with well-developed epipod; exopodite slender, furnished with setae at tip. Third maxilliped (Figure 4f, g) pediform, slender, overreaching scaphocerite by approximately half length of ultimate article; coxa with prominent hook-shaped lateral plate directed ventrally and strap-like epipod; antepenultimate article slender, proximal quarter bearing minute denticulation, possiblycorresponding to suture between ischium and merus; approximately 20 times as long as distal width, distally armed with spiniform seta and few rows of serrulate setae; penultimate article slender, almost 0.4 times as long as antepenultimate article, furnished ventromesially with serrulate setae; distally with clear division between propodus and dactylus, propodus furnished with serrulate setae on proximal third of ventromesial margin, median third with several slender spiniform setae, distal margin furnished with long setae, dactylus with five spiniform setae and several long setae at tip; exopod slender, reaching approximately mid-length of antepenultimate article.

First pereiopods (Figure 5a–d) similar in size and shape, enlarged, with dactylus of chela held dorsally; coxa with mastigobranch and setobranch; basis short; ischium about four times as long as wide, distal margin markedly oblique; merus slender, about nine times as long as broad, proximolateral margin with small spiniform seta; carpus more or less vase-shaped, distoventral margin with slender spiniform seta, distomesial margin with one transverse row of serrulate setae; chela slender, palm slightly swollen, about twice as long as high, with five transverse rows of serrulate setae on proximomesial margin, fingers about 1.3 times as long as palm; fingers subequal, excavated mesially, dactylus with minute serration on distal half of cutting edge, pollex simple on cutting edge.

Second pereiopods (Figure 5e, f) enlarged, slightly less robust than first pereiopods, with dactylus of chela held ventrally; coxa with mastigobranch and setobranch; basis short; ischium slightly widening towards distal margin, about eight times as long as proximal width, distoventral margin with broad, subrounded process; merus very slender, uniformly broad throughout its length, about 10 times as long as broad, slightly shorter than ischium; carpus short, about 0.5 times as long as merus, composed of two subarticles; chela with fingers elongate, about 2.5 times as long as palm; fingers subequal, strongly crossing each other; pollex with smooth cutting edge, mesial margin near tip with small, articulated, comb-like tooth; dactylus minutely serrated along entire cutting edge.

Third pereiopod (Figure 6a) slender; coxa with mastigobranch and setobranch; basis short; ischium about five times as long as broad, ventral margin armed with four spiniform setae; merus slender, about three times as long as ischium, approximately 15 times as long as broad, unarmed; carpus slender, about 12 times as long as broad, about 0.6 times as long as merus, dorsodistal margin with subrounded projection; propodus approximately as long as merus, ventral margin armed with 11 small spiniform setae in addition to distal pair, dorsal margin on distal third furnished with several plumose setae; dactylus biunguiculate, ventral margin with five accessory spinules decreasing in size proximally, superior unguis slightly longer than inferior unguis. Fourth pereiopod (Figure 6b, c) generally similar to third pereiopod; coxa with only setobranch; ischium armed with three spiniform setae on ventral margin; propodus with 13 minute spiniform setae on ventral margin in addition to distal pair. Fifth pereiopod (Figure 6d) more or less similar to third pereiopod; coxa lacking mastigobranch and setobranch; ischium unarmed; propodus with distal fifth furnished with transverse rows of serrulate setae.

First pleopod (Figure 6e) without specific features. Second pleopod (Figure 6f) in males with both appendix interna and appendix masculina.

Uropods (Figure 3i) with lateral lobe of protopod triangular, mesial lobe blunt; exopod ovoid, markedly overreaching endopod, distolateral margin with small tooth adjacent to spiniform seta, diaeresis complete, lateral margin near spiniform seta blunt; endopod without specific feature.

Variation

The carapace/rostral tooth formula is 2 + 4/2 in both paratypes.

Colour pattern

Body and appendages generally semi-transparent (Figures 2 and 7), tinged with red. Thorax with several red, interrupted transverse bands; pleonites 1–5 posteriorly with a red band (interrupted on first pleonite); pleonite 6 with two transverse bands. Antennae and antennules tinged with red; scaphocerite with scattered red patches; chelipeds (P1–2) with fingers reddish and distal red band on carpus; ambulatory pereiopods with red banding on coxa to carpus, propodus and dactylus transparent. Pleopod basis with distal red band. Uropods and telson with red banding.

Etymology

The specific epithet, epitelum, derives from the Greek epitelous, meaning finally; in reference to it having taken 58 years from first discovery to description; used as a noun in apposition.

Remarks

Caridion epitelum sp. nov. primarily differs from both C. steveni and C. gordoni in the gill formula. In the new species, mastigobranchs are present on the coxa of the third maxilliped and on the anterior three pereiopods, whereas in the other two species, a mastigobranch is also present on the fourth pereiopod (Kemp, Reference Kemp1910a: p. 110; Squires, Reference Squires1990: p. 166; Smaldon et al., Reference Smaldon, Holthuis and Fransen1993: pp. 58, 60).

Caridion epitelum sp. nov. shares with C. gordoni (Spence Bate, Reference Spence Bate1858) a straight rostrum reaching beyond the antennular peduncle. However, the rostrum is more dagger-shaped in Caridion epitelum sp. nov. The third maxilliped in C. gordoni appears distinctly longer than the scaphocerite, exceeding it by the length of the carpus (Kemp, Reference Kemp1910a: pl. XVI, Figure 1; Squires, Reference Squires1990: fig. 85a; Smaldon et al., Reference Smaldon, Holthuis and Fransen1993: fig. 18a). In the new species, in contrast, the third maxilliped is longer, overreaching the scaphocerite by approximately half the length of the propodus. The carapace/rostral tooth formula also differs between the two species: C. gordoni has 5–10 dorsal teeth, usually 7–8, and 1 ventral tooth, rarely 2–3, whereas Caridion epitelum sp. nov. has 5–6 dorsal teeth and 2 ventral teeth.

The rostral shape of C. steveni (Lebour, Reference Lebour1930) is markedly different from that of Caridion epitelum sp. nov. In C. steveni, the rostrum is slightly downcurved, somewhat shorter than the antennular peduncle, and has a tooth formula of 1 + 4–6/1. In contrast, the rostrum of Caridion epitelum sp. nov. distinctly overreaches the antennular peduncle and has a tooth formula of 2 + 3–4/2.

The colour pattern of the three species is also different. In C. gordoni, the body is transparent, with scattered red chromatophores distributed over the body (Kemp, Reference Kemp1910a; Smaldon et al., Reference Smaldon, Holthuis and Fransen1993; Berggren et al., Reference Berggren, Nyman and Pleijel2025; Baldock et al., Reference Baldock, Bolton and Dixon2026). In C. steveni, the red chromatophores are more densely distributed, giving the shrimp an almost entirely red appearance (Smaldon et al., Reference Smaldon, Holthuis and Fransen1993; Berggren et al., Reference Berggren, Nyman and Pleijel2025; Baldock et al., Reference Baldock, Bolton and Dixon2026). In Caridion epitelum sp. nov., however, the red chromatophores are arranged in transverse bands (Figures 2 and 7).

Based on the illustrations provided by Ledoyer (Reference Ledoyer1968) and García and Gracia (Reference García and Gracia1996), we consider the specimens reported by these authors to be conspecific with the taxon described herein.

Distribution and ecology

In addition to the above-mentioned types collected from the Figuier cave, near Marseille, and in Monaco, one further specimen was also collected at Jarre cave (43.196189ºN 5.365484ºE), 15 m, in May 2002 (Calanques National Park) and two more specimens from the caissons in Port Hercule, Monaco, in July 2005 at ca. 20 m depth. Environmental and biotic details of both Figuier Cave and Jarre Cave can be found in Derrien et al. (Reference Derrien, Chevaldonné and Pérez2024), whilst the environment at Port Hercule is described in Pérez et al. (Reference Pérez, Chevaldonné, Lejeusne, Antonioli, Graille, Harmelin, Le Diréach and Boudouresque2013). All confirmed observations of C. epitelum sp. nov. have been made in remote areas of underwater caves (i.e. the total-dark cave community), in the Calanques coast near Marseille at depths of about 15 m, and in the caissons of the counter breakwater at Port Hercule, Monaco, at depths of 15–35 m. When adding the earlier records from Villefranche-sur-Mer and Mallorca (Ledoyer, Reference Ledoyer1968; García and Gracia, Reference García and Gracia1996; Abelló et al., Reference Abelló, Carbonell and Torres2002), the geographical range includes the whole NW Mediterranean, with available information indicating that the species could be less cryptic at night and in deeper water, as is often the case in cave-dwelling species. If earlier larval records of the genus in the Mediterranean also refer to the new species, it may occur in the Adriatic Sea (Kurian, Reference Kurian1956) as well as the Bay of Algiers (Seridji, Reference Seridji1971).

Acknowledgements

H.A. is deeply grateful to Dr Laure Corbari and Dr Line Le Gall for their invitation to participate in the PEPR ATLASea Marseille-Endoume sampling workshop in 2025, which led to the discovery of the new material used in this study. We thank the Calanques National Park for granting us authorisation to collect biological material at Figuier Cave, the Monaco government’s Environmental Division for their support in assessing the biodiversity of the Port Hercule caissons, Dorian Guillemain and the OSU Institut Pythéas for diving and logistical assistance in Marseille. T. Pérez is acknowledged for allowing us to use his underwater photo; C. d’Udekem d’Acoz is thanked for examining the specimens of C. steveni; R.C. is also acknowledged for identifying the original nature of Mediterranean cave Caridion specimens as early as 2007.

Author contributions

H.A.: Methodology, Writing – original draft, Resources, Visualisation, Formal analysis, Writing – review and editing, Funding acquisition. P.C.: Resources, Writing – review and editing; S.D.G.: Conceptualisation, Writing – original draft, Writing – review and editing.

Declaration of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Data availability statement

The sequences used in this study are available in GenBank; accession numbers are provided in Table 1. The material examined herein is deposited in the collections of the Muséum National d’Histoire Naturelle, Paris, France (MNHN).

Ethics and approach

Ethical approval was not required for this study under local legislation and institutional requirements, as the study involved only invertebrates. Collection permits and related procedures were handled by the Muséum National d’Histoire Naturelle, Paris, France (MNHN).

Funding statement

This study was supported by the European Union under the LERCO project number CZ.10.03.01/00/22_003/0000003 via the Operational Programme Just Transition to HA. HA acknowledges The Nippon Foundation-Nekton Ocean Census Programme (https://oceancensus.org/) for supporting the discovery and description of the new species. This is Ocean Census Species Number OC-SP-0002250.

References

Abelló, P, Carbonell, A and Torres, P (2002) Biogeography of epibenthic crustaceans on the shelf and upper slope off the Iberian Peninsula Mediterranean coasts: Implications for the establishment of natural management areas. Scientia Marina 66(Suppl. 2), 183–198.10.3989/scimar.2002.66s2183CrossRefGoogle Scholar
Anker, A and Fransen, CHJM (2026) Establishment of Leontocarididae fam. nov. for Leontocaris Stebbing, 1905 (Decapoda: Caridea). Papéis Avulsos de Zoologia 66, e202666035[1–9].10.11606/1807-0205/2026.66.035CrossRefGoogle Scholar
Ashrafi, H and Baeza, JA (2025) Molecular phylogenetics of Thor Kingsley, 1878 and Thinora Bruce, 1997 (Decapoda: Caridea: Thoridae), with the relegation of Thinora to synonymy and the description of two new species of Thor, one cryptic. Journal of Crustacean Biology 45, ruaf022.10.1093/jcbiol/ruaf022CrossRefGoogle Scholar
Ashrafi, H, Baeza, JA and Ďuriš, Z (2021a) The caridean shrimps of the genus Lysmata Risso, 1816 (Decapoda: Lysmatidae) from Madagascar collected during the Atimo-Vatae expedition: A new species and two new records. European Journal of Taxonomy 774, 155–177.10.5852/ejt.2021.774.1535CrossRefGoogle Scholar
Ashrafi, H and De Grave, S (2023) A new species of Automate (Crustacea: Decapoda) from the Persian Gulf. Crustacean Research 52, 79–89.10.18353/crustacea.52.0_79CrossRefGoogle Scholar
Ashrafi, H, Ďuriš, Z and Anker, A (2021b) Aretopsis sandybrucei, a new deep-water shrimp (Malacostraca: Decapoda: Caridea: Alpheidae) from the Coral Sea. European Journal of Taxonomy 774, 42–57.10.5852/ejt.2021.774.1527CrossRefGoogle Scholar
Ashrafi, H, Ďuriš, Z and Anker, A (2022) The first complete specimen of the deep-water shrimp Batella praecipua De Grave, 2004 (Crustacea: Decapoda: Alpheidae). Zootaxa 5092, 378–386.10.11646/zootaxa.5092.3.8CrossRefGoogle Scholar
Ashrafi, H, Ďuriš, Z and Anker, A (2024) Description and phylogenetic position of a new genus and species of deep-water alpheid shrimp associated with glass sponges off New Caledonia (Decapoda: Caridea). Zoological Studies 63, 1–14.Google ScholarPubMed
Aznar-Cormano, L, Brisset, J, Chan, T-Y, Corbari, L, Puillandre, N, Utge, J, Zbinden, M, Zuccon, D and Samadi, S (2015) An improved taxonomic sampling is a necessary but not sufficient condition for resolving inter-families relationships in caridean decapods. Genetica 143, 195–205.10.1007/s10709-014-9807-0CrossRefGoogle Scholar
Baeza, JA (2013) Molecular phylogeny of broken-back shrimps, genus Lysmata and allies: A test of the ‘Tomlinson–Ghiselin’ hypothesis explaining the evolution of hermaphroditism. Molecular Phylogenetics and Evolution 69, 46–62.10.1016/j.ympev.2013.05.013CrossRefGoogle Scholar
Baeza, JA and Fuentes, MS (2013) Exploring phylogenetic informativeness and nuclear copies of mitochondrial DNA (numts) in three commonly used mitochondrial genes: Mitochondrial phylogeny of peppermint, cleaner and semi-terrestrial shrimps (Caridea: Lysmata, Exhippolysmata and Merguia). Zoological Journal of the Linnean Society 168, 699–722.10.1111/zoj.12044CrossRefGoogle Scholar
Baeza, JA, Schubart, CD, Zillner, P, Fuentes, S and Bauer, RT (2009) Molecular phylogeny of shrimps from the genus Lysmata (Caridea: Hippolytidae): The evolutionary origins of protandric simultaneous hermaphroditism and social monogamy. Biological Journal of the Linnean Society 96, 415–424.10.1111/j.1095-8312.2008.01133.xCrossRefGoogle Scholar
Baldock, L, Bolton, C and Dixon, IMT (2026) Marine Crustaceans of Britain and Ireland. Oxford: Princeton University Press.Google Scholar
Barnich, R (1996) The Larvae of the Crustacea Decapoda (Excl. Brachyura) in the Plankton of the Mediterranean Coast (Identification Keys and Systematic Review). Göttingen: Cuvillier Verlag.Google Scholar
Berggren, M, Nyman, L and Pleijel, F (2025) Nationalnyckeln till Sveriges Flora Och Fauna, Kräftdjur: krill-tiofotade Kräftdjur, Crustacea: euphausiacea-Decapoda. Uppsala: SLU Artdatabanken.Google Scholar
Bianchi, CN, Gerovasileiou, V, Morri, C and Froglia, C (2022) Distribution and ecology of decapod crustaceans in Mediterranean marine caves: A review. Diversity 14, 176.10.3390/d14030176CrossRefGoogle Scholar
Bourdillon-Casanova, L (1960) Le méroplancton du Golfe de Marseille: Les larves de crustacés décapodes. Recueil Design Travaux de Louisiana Station Marine d’Endoume 30, 1–286.Google Scholar
Bracken, HD, De Grave, S and Felder, DL (2009) Phylogeny of the infraorder Caridea based on nuclear and mitochondrial genes (Crustacea: Decapoda). In Martin, JW, Felder, DL and Crandall, KA (eds), Decapod Crustacean Phylogenetics. Crustacean Issues 18, 274–300.Google Scholar
Brattegard, T and Rømer, EI (1998) Decapoda Natantia (Crustacea) in the Faroe area. Fróðskaparrit, Faroese Scientific Journal 46, 91–126.Google Scholar
Buhl-Mortensen, L and Mortensen, PB (2004) Symbiosis in deep-water corals. Symbiosis (Philadelphia, Pa.) 37, 33–61.Google Scholar
Cartes, JE, Papiol, V, Frutos, I, Macpherson, E, González-pola, C and Punzón, A (2014) Distribution and biogeographic trends of decapod assemblages from Galicia Bank (NE Atlantic) at depths between 700 and 1800 m, with connections to regional water masses. Deep Sea Research Particles II: Topical Studies in Oceanography 106, 165–178.10.1016/j.dsr2.2013.09.034CrossRefGoogle Scholar
Castresana, J (2000) Selection of conserved blocks from multiple alignments for their use in phylogenetic analysis. Molecular Biology and Evolution 17, 540–552.10.1093/oxfordjournals.molbev.a026334CrossRefGoogle ScholarPubMed
Cedhagen, T and Hansson, HG (1995) Caridion steveni (Decapoda, Natantia, Hippolytidae), recorded on the Swedish west coast, and a new host species for Sylon hippolytes (Rhizocephala, Sylonidae). Crustaceana 68, 659–660.10.1163/156854095X01853CrossRefGoogle Scholar
Chevaldonné, P, Sket, B, Marschal, C, Lejeusne, C and Calado, R (2008) Improvements to the “Sket Bottle”: A simple manual device for sampling small crustaceans from marine caves and other cryptic habitats. Journal of Crustacean Biology 28, 185–188.10.1651/07-2923R.1CrossRefGoogle Scholar
Cho, JSR, Kim, YM, Sagong, J, Lee, JH, Yeo, MY, Bahn, SY, Kim, HM, Lee, GS, Lee, DH, Choo, YS and Pak, JH (2012) Biodiversity of marine invertebrates on rocky shores of Dokdo, Korea. Zoological Studies 51, 710–726.Google Scholar
Christodoulou, M, Derycke, S, Beentjes, KK, Hillewaert, H, Laakmann, S, Lundin, K, Kamyab, E, Khodami, S, Maes, S, Reiss, H and Uhlir, C (2025) A taxonomically reliable DNA barcode reference library for North Sea macrobenthos. Scientific Data 12, 1198.10.1038/s41597-025-05500-zCrossRefGoogle ScholarPubMed
Christoffersen, ML (1987) Phylogenetic relationships of hippolytid genera, with an assignment of new families for the Crangonoidea and Alpheoidea (Crustacea, Decapoda, Caridea). Cladistics: the International Journal of the Willi Hennig Society 3, 348–362.10.1111/j.1096-0031.1987.tb00898.xCrossRefGoogle ScholarPubMed
D’udekem D’acoz, C (1999) Inventaire et distribution des Crustacés Décapodes de l’Atlantique Nord-Oriental, de la Méditerranée et des Eaux Continentales Adjacentes au Nord de 25°N. Patrimoines Naturels 40. Paris: Muséum National d’Histoire Naturelle.Google Scholar
De Grave, S and Boyko, CB (2024) The carcinological oeuvre of Charles Spence Bate (1819–1889): Checklist of species and genera, dates of publication, and a list of publications (Crustacea: Amphipoda, Cirripedia, Cumacea, Decapoda, Tanaidacea). Journal of Crustacean Biology 44, ruae010.10.1093/jcbiol/ruae010CrossRefGoogle Scholar
De Grave, S, Chan, T-Y, Fujita, Y and Okuno, J (2012) Hippolytidae and Barbouriidae (Decapoda: Caridea) collected during the Ryukyu “KUMEJIMA 2009” expedition. In Naruse T, Chan T-Y, Tan HH, Ahyong ST and Reimer JD (eds), Scientific Results of the Marine Biodiversity Expedition — KUMEJIMA 2009. Zootaxa 3367, 95–102.Google Scholar
De Grave, S, Li, CP, Tsang, LM, Chu, KH and Chan, T-Y (2014) Unweaving hippolytoid systematics (Crustacea, Decapoda, Hippolytidae): Resurrection of several families. Zoologica Scripta 43, 496–507.10.1111/zsc.12067CrossRefGoogle Scholar
Derrien, M, Chevaldonné, P and Pérez, T (2024) Patterns of benthic diversity in marine underwater caves of the Marseille Region (France, North-Western Mediterranean Sea). Mediterranean Marine Science 25, 666–683.10.12681/mms.38566CrossRefGoogle Scholar
Ditter, RE, Mejía-ortíz, LM and Bracken-grissom, HD (2020) Anchialine adjustments: An updated phylogeny and classification for the family Barbouriidae Christoffersen, 1987 (Decapoda: Caridea). Journal of Crustacean Biology 40, 401–411.10.1093/jcbiol/ruaa037CrossRefGoogle Scholar
Edgar, RC (2004) MUSCLE: Multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research 32, 1792–1797.10.1093/nar/gkh340CrossRefGoogle ScholarPubMed
Fiedler, GC, Rhyne, AL, Segawa, R, Aotsuka, T and Schizas, NV (2010) The evolution of euhermaphroditism in caridean shrimps: A molecular perspective of sexual systems and systematics. BMC Evolutionary Biology 10, 297.10.1186/1471-2148-10-297CrossRefGoogle ScholarPubMed
García, L and Gracia, F (1996) Sobre algunes espècies de crustacis decàpodes interessants de les illes Balears (Crustacea: Decapoda). Bolletí de Louisiana Societat d’Història Natural de Les Balears 39, 177–186.Google Scholar
García Raso, JE (1987) Carideos Ibéricos (Crustacea, Decapoda): Síntesis. Miscellània Zoològica 11, 113–120.Google Scholar
Goës, A (1864) Crustacea decapoda podophthalma marina Sueciæ, interpositis speciebus norvegicus aliisque vicinis, enumerat. Öfversigt Af Kongliga Vetenskaps-Akademiens Förhandlingar 20, 161–180.Google Scholar
Grimes, S, Bakalem, A and Dauvin, JC (2016) Annotated checklist of marine Algerian crustacean decapods. Mediterranean Marine Science 17, 384–395.10.12681/mms.1420CrossRefGoogle Scholar
Hultgren, KM, Ossentjuk, L, Hendricks, KE and Serafin, A (2021) Crustacean diversity in the Puget Sound: Reconciling species, phylogenetic and functional diversity. Marine Biodiversity 51, 37.10.1007/s12526-021-01172-1CrossRefGoogle Scholar
Kemp, S (1910a) The Decapoda Natantia of the coasts of Ireland. Scientific Investigations of the Fisheries Board of Ireland. 1908, 1–190,pls1–23.Google Scholar
Kemp, S (1910b) The Decapoda collected by the “Huxley” from the north side of the Bay of Biscay in August 1906. Journal of the Marine Biological Association of the United Kingdom 8, 407–420.10.1017/S0025315400073689CrossRefGoogle Scholar
Klitgaard, A (1995) The fauna associated with outer shelf and upper slope sponges (Porifera, Demospongiae) at the Faroe Islands, northeastern Atlantic. Sarsia 80, 1–22.10.1080/00364827.1995.10413574CrossRefGoogle Scholar
Komai, T, Chang, SC and Chan, T-Y (2019) A new deep-sea species of the caridean shrimp genus Lebbeus White, 1847 (Crustacea: Decapoda: Thoridae) from southern Java, Indonesia. Raffles Bulletin of Zoology 67, 150–159.Google Scholar
Kumar, S, Stecher, G, Li, M, Knyaz, C and Tamura, K (2018) MEGA X: Molecular Evolutionary Genetics Analysis across computing platforms. Molecular Biology and Evolution 35, 1547–1549.10.1093/molbev/msy096CrossRefGoogle ScholarPubMed
Kurian, CV (1956) Larvae of decapod Crustacea from the Adriatic Sea. Acta Adriatica 6, 1–108.Google Scholar
Lebour, MV (1930) The larval stages of Caridion, with a description of a new species, C. steveni. Proceedings of the Zoological Society of London 1930, 181–194,pls1–8.Google Scholar
Ledoyer, M (1968) Ecologie de la faune vagile des biotopes méditerranéens accessibles en scaphandre autonome (région de Marseille principalement). IV – Synthèse de l’étude écologique. Recueil Design Travaux de Louisiana Station Marine d’Endoume, Faculté Design Sciences de Marseille 44, 125–295.Google Scholar
Ledoyer, M (1969) Remarques sur les Hippolytidae des côtes de Provence et description de Hippolyte leptometrae n. sp. Téthys 1, 341–348.Google Scholar
Letunic, I and Bork, P (2021) Interactive Tree Of Life (iTOL) v5: An online tool for phylogenetic tree display and annotation. Nucleic Acids Research 49, W293–W296.10.1093/nar/gkab301CrossRefGoogle ScholarPubMed
Li, CP, De Grave, S, Chan, TY, Lei, HC and Chu, KH (2011) Molecular systematics of caridean shrimps based on five nuclear genes: Implications for superfamily classification. Zoologischer Anzeiger-A Journal of Comparative Zoology 250, 270–279.10.1016/j.jcz.2011.04.003CrossRefGoogle Scholar
Martin, J (2004) Les larves de crustacés décapodes des côtes françaises de la Manche. identification, période, abondance. Plouzané: Editions Ifremer.Google Scholar
Ō Céidigh, P (1963) A List of Irish Marine Decapod Crustacea. Dublin: National Museum of Ireland.Google Scholar
Paula, J (1987) Seasonal distribution of Crustacea Decapoda larvae in S. Torpes Bay, south-western Portugal. Investigación Pesquera 51(Suppl. 1), 267–275.Google Scholar
Pérez, T, Chevaldonné, P, Lejeusne, C, Antonioli, AP, Graille, R and Harmelin, JG (2013) Des récifs artificiels d’un autre type: Les grottes du Prince de Monaco. In Le Diréach, L and Boudouresque, CF (eds), GIS Posidonie: plus de 30 ans au service de la protection et de la gestion du milieu marin. Marseille: GIS Posidonie Publications, 126–131.Google Scholar
Robinson, M and Tully, O (2000) Seasonal variation in community structure and recruitment of benthic decapods in a sub-tidal cobble habitat. Marine Ecology Progress Series 266, 181–191.10.3354/meps206181CrossRefGoogle Scholar
Ronquist, F, Teslenko, M, van der Mark, P, Ayres, DL, Darling, A, Höhna, S, Larget, B, Liu, L, Suchard, MA and Huelsenbeck, JP (2012) MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61, 539–542.10.1093/sysbio/sys029CrossRefGoogle ScholarPubMed
Sehein, T, Siuda, ANS, Shank, TM and Govindarajan, AF (2014) Connectivity in the slender Sargassum shrimp, Latreutes fucorum: Implications for a Sargasso Sea protected area. Journal of Plankton Research 36, 1408–1412.10.1093/plankt/fbu081CrossRefGoogle Scholar
Seridji, R (1971) Contribution à l’étude des larves de Crustacés Décapodes en Baie d’Alger. Pelagos 3, 1–107.Google Scholar
Smaldon, G, Holthuis, LB and Fransen, CHJM (1993) Coastal Shrimps and Prawns: keys and Notes for Identification of the Species. 2nd Edition. Synopses of the British Fauna (New Series), no. 15. Shrewsbury: Field Studies Council.Google Scholar
Smith, SI (1879) The stalk-eyed crustaceans of the Atlantic coast of North America north of Cape Cod. Transactions of the Connecticut Academy of Arts and Sciences. 5, 27–138,pls8–12.Google Scholar
Spence Bate, C (1858) A new British Hippolyte. Natural History Review 5, 51–53.Google Scholar
Squires, HJ (1990) Decapod Crustacea of the Atlantic coast of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences 221, 1–532.Google Scholar
Števčič, Z (1969) Lista desetonožnih Rakova Jadrana [List of Adriatic decapod Crustacea]. Biološki Vestnik 17, 125–134.Google Scholar
Števčič, Z (1990) Check-list of the Adriatic decapod Crustacea. Acta Adriatica 31, 183–274.Google Scholar
Terossi, M, De Grave, S and Mantelatto, FL (2017) Global biogeography, cryptic species and systematic issues in the shrimp genus Hippolyte Leach, 1814 (Decapoda: Caridea: Hippolytidae) by multimarker analyses. Scientific Reports 7, 6697.10.1038/s41598-017-06756-1CrossRefGoogle ScholarPubMed
Toon, A, Finley, M, Staples, J and Crandall, KA (2009) Decapod phylogenetics and molecular evolution. In Martin, JW, Crandall, KA and Felder, DL (eds), Decapod Crustacean Phylogenetics. Boca Raton, FL: CRC Press. 15–29.10.1201/9781420092592-c2CrossRefGoogle Scholar
Torres, AP, Dos Santos, A, Balbín, R, Alemany, F, Massutí, E and Reglero, P (2014) Decapod crustacean larval communities in the Balearic Sea (western Mediterranean): Seasonal composition, horizontal and vertical distribution patterns. Journal of Marine Systems 138, 112–126.10.1016/j.jmarsys.2013.11.017CrossRefGoogle Scholar
Vaidya, G, Lohman, DJ and Meier, R (2011) SequenceMatrix: Concatenation software for the fast assembly of multi-gene datasets with character set and codon information. Cladistics: the International Journal of the Willi Hennig Society 27, 171–180.10.1111/j.1096-0031.2010.00329.xCrossRefGoogle ScholarPubMed
Vinagre, C, Dias, M, Fonseca, C, Pinto, MT, Cabral, HN and Silva, A (2015) Use of rocky intertidal pools by shrimp species in a temperate area. Biologia 70, 372–379.10.1515/biolog-2015-0046CrossRefGoogle Scholar
Vives, F (1966) Zooplancton nerítico de las aguas de Castellón. Investigación Pesquera 30, 49–166.Google Scholar
Xia, X and Xie, Z (2001) DAMBE: Software package for data analysis in molecular biology and evolution. Journal of Heredity 92, 371–373.10.1093/jhered/92.4.371CrossRefGoogle ScholarPubMed
Figure 0

Table 1. Species included in the phylogenetic analysis, with GenBank accession numbers for partial fragments of the four genes 16S, COI, H3, and Enolase, and corresponding referencesTable 1 long description.

Figure 1

Table 2. Partition scheme, best-fit substitution models, and number of nucleotide positions used for phylogenetic tree reconstructionTable 2 long description.

Figure 2

Figure 1. Phylogenetic tree reconstructed from concatenated partial fragments of four genes, 16S, COI, H3, and Enolase (ENO1), using Maximum Likelihood and Bayesian Inference analyses for Hippolytidae and related families. Each terminal is labelled with the corresponding species name; GenBank accession numbers are provided in Table 1. Bayesian posterior probabilities and bootstrap support values are shown above and below branches, respectively.Figure 1 long description.

Figure 3

Figure 2. Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241, live colouration: (a) Dorsal view; (b) lateral view.

Figure 4

Figure 3. Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Frontal region, dorsal view; (b) same, lateral view; (c) anterior carapace and rostrum, lateral view; (d) proximal portion of antennule, ventral view; (e), posterior four thoracic sternites, ventral view; (f) posterior carapace and pleon, lateral view; (g) anterior four pleonites, ventral view; (h) sixth pleonite, posteroventral view; (i) telson and uropods.

Figure 5

Figure 4. Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Mandible; (b) maxillule; (c) maxilla; (d) first maxilliped; (e) second maxilliped; (f) third maxilliped; (g) same, distal portion of ultimate article, showing propodus and dactylus.

Figure 6

Figure 5. Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) First pereiopod, lateral view; (b) same, mesial view; (c) chela of first pereiopod, lateral view; (d) same, fingers, mesial view; (e) second pereiopod, lateral view; (f) same, fingers, mesial view.

Figure 7

Figure 6. Caridion epitelum sp. nov., holotype, male, 8.7 mm, Marseille, France, MNHN-IU-2022-5241: (a) Third pereiopod, lateral view; (b) fourth pereiopod, lateral view; (c) same, distal portion of propodus and dactylus, mesial view; (d) fifth pereiopod, lateral view; (e) first pleopod; (f) second pleopod.

Figure 8

Figure 7. Caridion epitelum sp. nov., in situ (specimen not collected), caisson C3, counter breakwater, Port Hercule, Monaco, 35 m; 06.12.2011; photo by T. Pérez.