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Alpheus euphrosyne De Man, 1897 and A. microrhynchus De Man, 1897, two taxonomically challenging snapping shrimps without extant original type material, are rediagnosed based on recently collected and older museum material and adhering closely to their original descriptions. Two male specimens from Java and Kalimantan are designated as neotypes for A. euphrosyne and A. microrhynchus, respectively. Alpheus tirmiziae Kazmi, 1974 is placed in the synonymy of A. euphrosyne. The distributional range of A. euphrosyne extends from the South China Sea through the Sunda Shelf to the northern Arabian Sea. Alpheus eurydactylus De Man, 1920 is removed from the synonymy of A. euphrosyne and redescribed based on De Man’s type material from Java and new material from South-East Asia, Indonesia and northern Australia. Alpheus richardsoni Yaldwyn, 1971, previously often regarded as a subspecies of A. euphrosyne, is confirmed as a valid species morphologically and ecologically distinct from A. euphrosyne. In addition, A. richardsoni is geographically separated from A. euphrosyne, being confined to subtropical and temperate waters of Australia and New Zealand. Alpheus microrhynchus appears to be geographically restricted to South-East Asia, with confirmed records from Thailand, peninsular Malaysia and Borneo, where it occurs in transitional freshwater to brackish water habitats. Alpheus cyanoteles Yeo & Ng, 1996 is currently seen as the only true freshwater snapping shrimp. This unique species is morphologically almost identical with A. microrhynchus and is presently known only from a few localities in southern Thailand, peninsular Malaysia and western Borneo (Sarawak). Three species that were previously confused with A. euphrosyne, A. euphrosyne euphrosyne or A. euphrosyne richardsoni, are described as new to science: A. nomurai sp. nov. from Japan, Korea and Taiwan; A. takla sp. nov. from South-East Asia, Philippines, Indonesia, Papua New Guinea and Australia; and A. mangalis sp. nov. from Singapore, Malaysia, Philippines, Indonesia, northern Australia, Taiwan and possibly New Caledonia. Alpheus takla sp. nov. may represent the largest presently known snapping shrimp, with the total body length reaching 90 mm and the length of the major chela reaching 52 mm; this species, locally known as takla, is consumed in some parts of the Philippines. The taxonomic identity of the material from the western and northern Indian Ocean previously reported as A. euphrosyne euphrosyne remains uncertain. Alpheus malabaricus songkla Banner & Banner, 1966 is tentatively elevated to species rank, as Alpheus songkla stat. nov. This taxon remains problematic, mainly because the original type material from Songkhla Lake, Thailand, is composed exclusively of females; its status is discussed based on the reexamination of type specimens and material tentatively identified as A. cf. songkla, which appears to have some affinities with both A. songkla and A. eurydactylus. In addition, taxonomic, biogeographic and/or ecological remarks are provided for five further species, which in the past were compared with A. euphrosyne, A. richardsoni and A. microrhynchus or are morphologically similar to them. These species are: A. paludicola Kemp, 1915 from India; A. nipa Banner & Banner, 1985 from Indonesia; A. bunburius Banner & Banner, 1982 from western Australia; A. pontederiae de Rochebrune, 1883 from both sides of the Atlantic Ocean; and A. firmus Kim & Abele, 1988 from the tropical eastern Pacific. The heterogeneity of the Panamanian and Mexican material currently assigned to A. firmus is discussed in more detail.

A new snapping shrimp species of the Alpheus edwardsii (Audouin, 1826) group is described based on two specimens, one male and one female, collected on shallow-water reef flats of the Southern Ari Atoll in the Maldives, with a photographic record from Cebu in the Philippines. Alpheus octocellatus sp. nov. appears to be morphologically closest to A. edwardsii, A. pareuchirus Coutière, 1905, and A. leptochirus Coutière, 1905, but can be distinguished from all of them by a combination of morphological characters, mainly involving the chelipeds, third maxilliped and pleonal sternites. The new species also has a highly diagnostic colour pattern, with four pairs of conspicuous eyespots distributed in a unique and peculiar pattern on the pleon.

Two new species of the genus Onycocaris are described, based on single specimens from Fiji and Moorea respectively. Onycocaris iti sp. nov. is closely related to the relatively widespread species, O. seychellensis Bruce, 1971; whilst O. brucei sp. nov. is a pseudo-cryptic species allied to O. quadratophthalma (Balss, 1921).

Two new symbiotic species of decapod crustaceans, a palaemonid shrimp and a porcellanid crab, are described from the same type locality situated on the campus of the King Abdullah University of Science and Technology (KAUST) in Thuwal, on the Red Sea coast of Saudi Arabia. The palaemonid shrimp Palaemonella jamila sp. nov. is described based on one male and one female, whereas the porcellanid crab Enosteoides habibi sp. nov. is described based on three males and two females. Unfortunately, the originally collected and studied specimens were lost shortly after study. However, subsequent recollection of one specimen of P. jamila sp. nov. and one specimen of E. habibi sp. nov. enabled to deposit a holotype of each new species in the collections of the Florida Museum of Natural History, Gainesville, USA. Both species inhabit burrows of goby-associated snapping shrimps, Alpheus spp., in the shallow subtidal areas, at depths less than 1 m. In addition, a single female specimen of Palaemonella aliska Marin, 2008 collected at Al Fahal reef off KAUST represents the first record of the species in the Red Sea and the Indian Ocean, and a considerable range extension of its previously known distribution range. This species may be a close relative of P. jamila sp. nov., to which it is also ecologically similar. The present study highlights the necessity of prospecting the largely neglected and still undersampled shallow subtidal habitats of the Red Sea, and the Indo-West Pacific in general.

A new snapping shrimp species of the Alpheus macrocheles (Hailstone, 1835) group is described based on a single adult male specimen collected on an exposed forereef near Magoodhoo Island, Faafu Atoll, Maldives. Alpheus dingabadi sp. nov. is one of several species of the A. macrocheles group characterised by the presence of a stout distoventral tooth on the merus of the third pereiopod, but can be separated from all of them by several morphological features, including the unusually long appendix masculina on the second pleopod, as well as by its conspicuous and highly diagnostic colour pattern.

A new genus, Jogoya, gen. nov., is established for a new species of stenopodid shrimp, Jogoya alucia sp. nov., the holotype and single specimen of which was collected during a manned submersible dive in the Bahamas in 2019, and two additional specimens collected during earlier expeditions, one also from the Bahamas and one from Anguilla. The new genus appears to occupy an intermediate position between Richardina A. Milne-Edwards, 1881 and Odontozona Holthuis, 1946. Jogoya gen. nov. is characterised by the presence of unusually large spines on the cervical cincture of the carapace, a feature shared with a species originally described as Odontozona foresti Hendrickx, 2002 and herein tentatively transferred to Jogoya gen. nov., as Jogoya foresti (Hendrickx, 2002), comb. nov. The most conspicuous morphological difference between J. alucia sp. nov. and J. foresti is in the armature of the posterior half of the carapace, with the latter species having a post-cervical cincture armed with strong spines, which is absent in the new species. The two species of Jogoya gen. nov. also differ greatly by their colour patterns.

Two snapping shrimps associated with gobies are reported from the Saudi Arabian coast of the Red Sea. Alpheus karplusi sp. nov., a species with a highly diagnostic, rusty-spotted colour pattern, is described based on three specimens, two males and one female, collected in the Farasan Islands and off Thuwal. Alpheus thompsoni Anker, 2022, previously known with certainty only from Papua New Guinea, is reported from the Farasan Islands, on the basis of a complete adult male specimen. Some differences in the colour pattern and morphology between the female holotype from Papua New Guinea and the male from the Red Sea are discussed. Both species belong to the A. djeddensis Coutière, 1897—A. djiboutensis De Man, 1909 species complex, which also includes A. bellulus Miya & Miyake, 1969, A. macellarius Chace, 1988, A. fenneri Bruce, 1994, A. mannarensis Purushothaman, Abhilash, Kumar & Lal, 2021, and A. sciolii Anker, 2022.

A new alpheid shrimp genus, Crosnierocaris gen. nov., is established for Crosnierocaris athanasoides sp. nov., a very peculiar shrimp possibly associated with decomposing sea grass accumulations in deeper water. The type series of C. athanasoides sp. nov. was collected in the Mozambique Channel, north of Grande Glorieuse Island, at a depth of 240–255 m. The new genus presents a unique combination of morphological features, including the very long, slender rostrum armed with a subdistal ventral tooth; the pterygostomial angle projecting as a strong sharp tooth; the third to fifth pleura with their distoventral margins armed with two to four small teeth, a unique feature within the Alpheidae; the sixth pleuron with an articulated plate; the eyes largely exposed dorsally and laterally; the first pereiopods (chelipeds) feebly enlarged in both sexes, stouter but shorter than walking legs; the first pereiopod carpus with rows of short serrulate setae on its mesial surface; the second pereiopod carpus with five subdivisions; the third to fifth pereiopods with meri armed with stout cuspidate setae; the uropodal diaeresis with a strongly dentate lateral portion; and the complete gill-exopod formula, with mastigobranchs on coxae of the third maxilliped and first to fourth pereiopods. Within alpheid shrimps, the rostrum of C. athanasoides sp. nov. is one of the longest relative to the total body length, often reaching half of the carapace length. The phylogenetic position of Crosnierocaris gen. nov. within the Alpheidae remains to be determined, but based on its morphological characters, the new genus appears to be closest to Athanas Leach, 1814, especially in the configuration of the frontal area of the carapace, and Potamalpheops Powell, 1979, for instance, in the armature of the uropodal diaeresis and walking legs, as well as the presence of setal rows on the cheliped carpus. The new genus also shares several morphological features with Yagerocaris Kensley, 1988, which represents one of the least derived lineages within the family Alpheidae.

A new stomatopod-associated species of the alpheid shrimp genus Athanas Leach, 1814 is described based on several specimens collected in shallow waters of northern New Caledonia. Athanas philippei n. sp. differs from all of its congeners by a unique combination of morphological characteristics, as well as a diagnostic colour pattern. All specimens of A. philippei n. sp. were collected from burrows, including one with its host, a large tiger mantis shrimp, Lysiosquillina maculata (Fabricius, 1793) (Lysiosquillidae). Thus, the new species represents the fifth species of Athanas known or presumed to be associated with the spacious burrows of stomatopods.

Leptalpheus lirai sp. nov., a new species of symbiotically living, infaunal alpheid shrimp, is described based on a single specimen from the Gulf of Santa Fe, Sucre, Venezuela. The new species belongs to an informal group of nine species within the genus Leptalpheus Williams, 1965, which is characterised by the presence of well-developed adhesive disks on the major chela. In addition, Leptalpheus axianassae Dworschak & Coelho, 1999 and Fenneralpheus chacei Felder & Manning, 1986 are recorded for the first time from Venezuela (Anzoátegui and Sucre, respectively), the latter also representing the first record of the genus Fenneralpheus Felder & Manning, 1986 for the country. These records bring to 11 the number of alpheid genera, and to four the number of species of Leptalpheus, known in Venezuelan marine waters.

During a survey of the mangrove infauna on the Iranian side of the Persian Gulf and the Gulf of Oman several specimens of a new alpheid shrimp, Salmoneus shojaei sp. nov., were collected around pneumatophores of mangrove trees, mostly in association with the larger burrowing snapping shrimps of the genus Alpheus Fabricius, 1798. The new species appears to be a member of the S. gracilipes species group and is morphologically closest to S. colinorum De Grave, 2004 and S. alpheophilus Anker & Marin, 2006. However, a unique combination of morphological characters, such as the carapace without rostral carina, the unarmed ischium of the major cheliped, the armed ischia of the minor cheliped and second pereiopod, the very slender dactyli of the fourth and third pereiopods, and the posterior margin of the telson with a deep U-shaped notch, distinguishes the new species from all other members of the S. gracilipes group. In addition, S. shojaei sp. nov. presents a diagnostic, albeit very faint, banding of the pleon, which separates it from most other species of the S. gracilipes group with known colour patterns. A DNA barcode (a partial fragment of the mitochondrial gene, CO1), as well as partial fragments of the mitochondrial 16S rRNA and the nuclear H3 genes, are provided to genetically characterise the new taxon.

A new snapping shrimp, Alpheus richpalmeri sp. nov., is described based on three specimens collected in the muddy–rocky intertidal of São Tomé Island, Gulf of Guinea, tropical eastern Atlantic. The new species belongs to the Alpheus brevirostris (Olivier, 1811) species group, sharing a series of morphological features and a similar colour pattern with two Atlantic species of the group, e.g., Alpheus roblesi Bracken-Grissom and Felder, 2014 and Alpheus ulalae Bracken-Grissom and Felder, 2014, as well as with the Indo-West Pacific Alpheus platyunguiculatus (Banner, 1953). The new species may have been previously reported from the tropical eastern Atlantic by A. Crosnier and J. Forest (1966. Ann. Inst. Oceanogr. Monaco, 44: 199–314) under the name Alpheus floridanus floridanus Kingsley, 1878, which is clearly different from the lectotype of Alpheus floridanus Kingsley, 1878 upon which H.D. Bracken-Grissom and D.L. Felder (2014. Zootaxa, 3895(4): 451–491) based their redescription of this species. The form previously known as Alpheus floridanus var. africana Balss, 1916, or Alpheus floridanus africanus, is elevated to full species rank as Alpheus africanus stat. nov., based on morphological differences and geographical separation from A. floridanus.

A new species of telescope shrimp, Ogyrides sindibadi sp. nov. is described from Kuwait. The new species is morphologically similar to O. striaticauda Kemp, 1915, originally described from Chilka Lake (India), but can be distinguished by the shape of the scaphocerite, the much longer dactylus of the third pereiopod, as well as the shape of the distal margin of the telson.

Three new species of the alpheid shrimp genus Salmoneus Holthuis, 1955 are described from the Red Sea coast of Saudi Arabia: S. farasan sp. nov. from the Farasan Islands; S. arabicus sp. nov. from Thuwal and Farasan Banks; and S. kausti sp. nov. from Thuwal. Salmoneus poupini Anker, 2011, previously known from French Polynesia and the Philippines, is reported for the first time from the Red Sea, based on material from Thuwal, Farasan Banks and Farasan Islands. In addition, the previously known distributional range of the closely related S. komaii Anker, 2011 is extended from the Mariana Islands to French Polynesia.

The deep-water alpheid shrimp Batella praecipua De Grave, 2004 was originally described based on two incomplete specimens, both with their first chelipeds missing, collected at 400–440 m off New Caledonia. During the recent KANADEEP 1 expedition in the Coral Sea in 2017, the first complete specimen of B. praecipua was collected at a depth of 370–380 m. The morphology of this specimen is presented in detail, with emphasis on the highly diagnostic chelipeds, which are described and illustrated for the first time. A slight intraspecific variation of B. praecipua is reported and a DNA barcode (CO1) is provided for this species. The main differences between the three presently known species of Batella Holthuis, 1955 are discussed.

The rare symbiotic alpheid shrimp Salmoneus erasimorum Dworschak, Abed-Navandi & Anker, 2000 was previously known from a single specimen collected with a suction pump on the Croatian coast in the Adriatic Sea, together with its host, the ghost shrimp, Gilvossius tyrrhenus (Petagna, 1792). A second record of S. erasimorum is presented here, with a diagnosis and the first colour photographs, based on a single specimen collected in northern Brittany, France, also with a suction pump, but without its host. This is also the first record of the species on the European coast of the Atlantic Ocean. An annotated list and a key to the species of Salmoneus currently known from the eastern Atlantic and the Mediterranean Sea are provided.

One of the most notable evolutionary innovations of marine invertebrates is the snapping claw of alpheid shrimps (Alpheidae), capable of generating a powerful water jet and a shock wave, used for defense, aggression, excavation, and communication. Evolutionary analysis of this character complex requires the study of a suite of complementary traits to discern pre-adaptations or post-adaptations of snapping behavior. A comprehensive phylogenetic analysis of the Alpheidae based on two mitochondrial and four nuclear markers, covering 107 species from 38 genera (77.6% generic coverage), is presented. Ancestral state reconstruction analyses revealed five independent origins of snapping, two of which relate to the morphologically similar but phylogenetically distant genera Alpheus and Synalpheus, highlighting significant convergence. The evolution of the five complementary traits (adhesive plaques, tooth-cavity system, dactylar joint type, chela size enlargement, and orbital hood) did not always show a significant correlation with the evolution of snapping overall, sometimes only in a few lineages, suggesting different evolutionary pathways were involved and demonstrating the versatility in the evolution of the snapping mechanisms.

A new alpheid shrimp, Aretopsis sandybrucei sp. nov., is described on the basis of three specimens collected from three deep-water banks in the Chesterfield Plateau of the Coral Sea, between New Caledonia and Queensland, Australia, at a depth range of 280–550 m. The new species is the first known deep-water species of the genus Aretopsis De Man, 1910, with its two congeners, A. amabilis De Man, 1910 and A. manazuruensis Suzuki, 1971, being confined to the lower intertidal and shallow subtidal areas, to a maximum depth of 50 m. Based on morphological grounds, A. sandybrucei sp. nov. can be easily separated from A. amabilis and A. manazuruensis by the generally much stouter third to fifth pereiopods, with their dactyli each bearing a very small secondary unguis on the flexor margin, in comparison to a much stronger one in the other two species. Aretopsis sandybrucei sp. nov. also differs from A. amabilis and A. manazuruensis by the less contrasting colour pattern, including the more translucent, dull yellowish chelae and tail fan. An association of A. sandybrucei sp. nov. with a deep-water hermit crab appears to be highly likely due to the presence of several large hermit crabs (Paguridae) in at least one of the three dredge/bottom trawl hauls, which was also containing a paratype of the new species. The taxonomic status of A. amabilis and A. manazuruensis is discussed.

We report on a recent collection of caridean shrimps from St. Helena in the south-central Atlantic Ocean, raising the total number of species known from the island to 24. Six species are newly recorded for the area, with no endemic species present. Additional three species are recorded from Ascension Island. A close biogeographical connection between the caridean faunas of St. Helena and Ascension Island is evident. Centre for Marine Sciences (CCMAR) of the University of Algarve, through the Portuguese Foundation for Science and Technology project [UID/Multi/04326/2013]

Thor amboinensis (De Man, 1888), known as “sexy shrimp” or “anemone squat shrimp” and popular among divers and aquarists, was previously believed to have a worldwide distribution, with populations throughout the tropical parts of the Indo-Pacific and Atlantic Ocean. However, consistent differences in some details of the colour pattern strongly suggest that T. amboinensis does not represent a single species, but a pantropical species complex. A recent phylogeographic analysis of T. amboinensis based on molecular data confirmed that this taxon is composed of at least five putative cryptic or pseudocryptic species. In the present study, a new cryptic species, Thor dicaprio sp. nov., is established for the western Atlantic populations previously referred to as T. amboinensis. The new species can be distinguished from all other members of the T. amboinensis complex by two differences in the colour pattern and a subtle difference in the size and setation of the appendix masculina, the latter yet to be confirmed. The conspicuous red-white banding of the antennal flagella appears to be the most diagnostic feature of the new species. In addition, T. dicaprio sp. nov. forms a genetically distinctive, homogeneous, tropical western Atlantic (TWA) clade, with the COI pairwise genetic distances from other clades ranging from 8.8% to 19.2%. The distribution of T. dicaprio sp. nov. includes the entire Caribbean Sea, parts of the Gulf of Mexico, Florida, Bahamas, Bermuda, as well as some offshore localities off northern and eastern Brazil. The main aspects and biology and ecological variability of T. dicaprio sp. nov. are discussed in the light of phylogeographic data presently available for the T. amboinensis complex.

The Indo-West Pacific emperor shrimp, Zenopontonia rex (Kemp, 1922) from the family Palaemonidae, was hitherto known as a peaceful symbiotic crustacean, feeding on very small organisms or detritus and other organic particles trapped in its varied hosts’ mucus. However, at two occasions in Indonesia, Z. rex was observed capturing and subduing relatively large and agile animals, representing completely new observations for the species’ diet and feeding behaviour. In the first case, Z. rex associated with the large chromodorid nudibranch Ceratosoma tenue Abraham, 1876 captured another palaemonid shrimp (Cuapetes sp.), only slightly smaller in size. In the second case, two individuals of Z. rex associated with a sea star, Echinaster luzonicus (Gray, 1840), were seen actively exploring the substrate under the star’s arms and one of them eventually captured and killed a juvenile/post-larval fish, probably a goby (Gobiidae). The second case represents one of the few in situ observations of a caridean shrimp killing a vertebrate.

The very uncommon alpheid shrimp Bermudacaris britayevi Anker, Poddoubtchenko & Marin, 2006, previously known only from the incomplete holotype from Nha Trang Bay, Vietnam, is recorded from Guam, Mariana Islands, extending its previously known distribution range into the oceanic islands of the western Pacific. The single specimen from Guam, an ovigerous female, was collected adjacent to a near-shore coral reef, on fine sand under a large piece of coral rubble, at a depth of about 10 m. This habitat is different from the collection data of the holotype, which was extracted from a burrow of unknown host on an intertidal sand-mud flat close to mangroves. Despite these ecological differences, the specimen from Guam corresponds to the holotype of B. britayevi in all diagnostic morphological characters and can be distinguished from the closely related B. australiensis Anker & Komai, 2004 and B. harti Anker & Iliffe, 2000. Since the holotype of B. britayevi was lacking one of the chelipeds, the complete specimen from Guam enables to complement the original description of the species. The stouter (= major) cheliped of the Guam specimen is illustrated to show a marked difference in the armature of the cheliped fingers, between the left and right cheliped. The colour pattern of B. britayevi, which was superficially described in the original description, is herein illustrated by photographs of the living individual. The relatively low number and large size of eggs in the Guam specimen of B. britayevi suggests an abbreviated larval development in this species.

Two new species of the palaemonid shrimp genus Typton Costa, 1844 are described based on material from Panama and Mexico. Both species are closely related to T. tortugae McClendon, 1911, a species originally described from the Dry Tortugas, off southern Florida, USA, and later scarcely recorded from other western Atlantic localities, from Bermuda to Mexico and Brazil. Some clarification and additional illustrations are provided for the type material of T. tortugae. Typton jonkayei sp. nov., is described based on material from fouling-encrusting communities dominated by sponges, growing on submerged roots of the red mangrove, Rhizhophora mangle L., in Bocas del Toro, Caribbean coast of Panama. This new species differs from T. tortugae in several morphological details, for instance, on the minor and major chelipeds (second pereiopods), telson, uropod, frontal margin and ambulatory pereiopods. Typton cousteaui sp. nov. is described based on a single ovigerous female dredged in the southern Gulf of California off Baja California Sur, Mexico, previously reported as T. tortugae. This new taxon seems to represent a true cryptic species with no significant morphological divergence from the allopatrically isolated T. tortugae, except for slight morphometric differences. In addition, T. granulosus Ayón-Parente, Hendrickx & Galvan-Villa, 2015 is recorded from the Pacific coast of Panama, based on material collected in the Coiba Archipelago. Some taxonomic, distributional and ecological remarks are provided for T. granulosus and the closely related T. serratus Holthuis, 1951.

Alpheus viserion sp. n. is described based on the material from Bocas del Toro archipelago on the Caribbean coast of Panama. The new species is morphologically closest to three members of the speciose A. armillatus H. Milne-Edwards, 1837 species complex, viz. A. carlae Anker, 2012, A. angulosus McClure, 2002, and A. tenuis Kim & Abele, 1988, differing from them, as well as from all the other species currently included in this complex, by a suite of morphological characters and a diagnostic colour pattern. With the description of yet another new shrimp species from Bocas del Toro, the authors hope to contribute to the awareness that this archipelago represents one of the most biologically diverse places in the Caribbean Sea and to encourage the preservation of the remaining natural habitats of this unique area.

A new palaemonid shrimp genus, Opaepupu gen. nov., is established to accommodate a new species of bivalve-associated shrimp, Opaepupu huna sp. nov. from Hawaii. A single mated pair, the female holotype and the male allotype, were found inside the trapezid bivalve Trapezium oblongum (Linnaeus, 1758) at a depth of 14 m in Kâne’ohe Bay, Hawai’i. The new genus is characterised by the rostrum being proximally broad, distally pointed, mid-dorsally carinate, and non-dentate; the anterolateral margin of the carapace without supraorbital, hepatic or epigastric teeth, but with a strong sharp antennal tooth; the sixth pleonite posteriorly unarmed; the telson medially depressed, with the dorsal surface armed with two pairs of submarginal cuspidate setae and with the posterior margin armed with two pairs of spiniform setae; the distolateral angle of the first article of the antennular peduncle without a sharp tooth; the mandible without a palp; the maxillular palp furnished with one long stiff seta dorsal to a small tooth-like extension; the first maxilliped without a palp; the third maxilliped not being operculate; the second pereiopods moderately robust, relatively slender, subequal, subsymmetrical, with simple teeth on the cutting edges of the fingers; the ambulatory pereiopods being slender, each ending in an elongate biunguiculate dactylus; and the uropodal exopod with a faint diaeresis and greatly reduced distolateral spiniform seta. The phylogenetic position of Opaepupu gen. nov. remains unclear, although it does not appear to be closely related to other bivalve-associated palaemonid genera.

Bannereus chani sp. nov. (Caridea: Alpheidae) is described based on a single female specimen collected off south-eastern Taiwan, at a depth of 301–356 m, being the second only species in the genus Bannereus Bruce, 1988. The ovigerous female holotype of the new species differs from the female holotype of B. anomalus Bruce 1988, the type species of the genus, by a series of important morphological characters, for instance, on the major cheliped and third pereiopod, strongly indicating that they represent two distinct species. The non-type male specimen tentatively identified as B. anomalus by Bruce (1988) may well belong to the new species, since it differs from the holotype of B. anomalus essentially by the same criteria as the female holotype of B. chani sp. nov. In addition, B. anomalus is newly recorded from the New Caledonian side of the Coral Sea.

Manaxius paullus, a new species of axiid burrowing shrimp, is described on the basis of a female holotype from the Society Islands, French Polynesia, and a female paratype from the Ryukyu Islands, Japan. Both specimens were collected on shallow coral reefs. The new species is morphologically closest to five of 17 congeners, viz., M. euophthalmus (de Man, 1905), M. izuensis (Komai, 2011), M. mimasensis (Sakai, 1967), M. poupini (Komai, 2016) and M. supia Poore, 2020, but can be separated from all of them by the rostrum being relatively broad and with one pair of lateral spines, in addition to a pair of supraocular spines; the presence of a subdistal spine on the dorsal margin of the cheliped ischium; the presence of additional three or four small spines on each cheliped palm, adjacent to the dorsal margin; and the lack of a spine near the base of the fingers of each cheliped palm.

Two new deep-water species of the snapping shrimp genus Alpheus Fabricius, 1798 are described based on the material collected by the expeditions BIOPAPUA, BOA1 and MIRIKY, organised by the Muséum National d’Histoire Naturelle in Paris. Alpheus alaincrosnieri n. sp. from the A. brevirostris (Olivier, 1811) group is described based on material dredged at depths of 198–408 m near the coasts of Papua New Guinea, Vanuatu and Madagascar. This species also occurs in the Philippines, based on morphological characters of a mutilated specimen from Masbate reported by Chace (1988). Alpheus alaincrosnieri n. sp. is unique within the A. brevirostris group, in having small orbital teeth. In most other features, A. alaincrosnieri n. sp. is morphologically closest to A. kagoshimanus Hayashi & Nagata, 2000, A. longipalma Komai & Ohtomi, 2018, A. macroskeles Alcock & Anderson, 1894, A. nonalter Kensley, 1969 and A. acutocarinatus De Man, 1909. Alpheus vanuatu n. sp. is described based on several specimens dredged at depths of 231–331 m off Espirito Santo, Vanuatu. This species most likely represents a deep-water member of the newly defined A. paracrinitus species group, sharing most morphological characters with A. tenuipes De Man, 1910 and A. labis Banner & Banner, 1982.