Snapping Shrimp Genus Alpheus Research Articles

Morphological and molecular approaches revealed a new species of snapping shrimp genus Alpheus Fabricius, 1798 (Decapoda: Caridea: Alpheidae) from Lakshadweep Islands, India

A new species of the alpheid genus Alpheus Fabricius, 1798, Alpheus sulcipalma sp. nov., is described and illustrated based on the specimens collected from the intertidal zone of Agatti Island, Lakshadweep, India at 0.5-1.0 m depth. This species belongs to the A. edwardsii group by absences of tooth in the orbital hoods and presence of compressed major chela with dorsal and ventral notches. Alpheus sulcipalma sp. nov. is morphologically closely related with A. pacificus Dana, 1852, absence of balaeniceps crests in the minor chela and absences of spine in the merus of major pereiopod of both sexes. However, the new species differs from A. pacificus in presence of strong and broad triangular groove on the dorsolateral and dorsomesial surface of the palm of major chela; length ratio and armature of fingers and palm of minor chela, carpus segments of second and third pereiopods and telson length. The results of phylogenetic analyses using partial sequences of mitochondrial COI gene data compared between A. sulcipalma sp. nov. with congener species which strongly support the description of new species with available limited sequences. The interspecific genetic divergences of the COI gene for A. sulcipalma sp. nov. and A. pacificus were observed higher in ranges (11.1-28.9%).

First worldwide molecular phylogeny of the morphologically and ecologically hyperdiversified snapping shrimp genus Alpheus (Malacostraca: Decapoda)

Hyperdiverse animal groups raise intriguing questions regarding the factors that generate and maintain their diversity. The snapping shrimp genus Alpheus (with >300 described species) is a spectacularly diversified group of decapod crustaceans that serves as an exemplary system for addressing evolutionary questions regarding morphological adaptations, symbiosis, cryptic diversity and molecular divergence. A lack of information regarding evolutionary relationships among species has limited investigations into the mechanisms that drive the diversification of Alpheus. Previous phylogenetic studies of Alpheus have been restricted in scope, while molecular datasets used for phylogenetic reconstructions have been based solely on mitochondrial and a handful of nuclear markers. Here we use an anchored hybrid enrichment (AHE) approach to resolve phylogenetic relationships among species of Alpheus. The AHE method generated sequence data for 240 loci (>72,000 bp) for 65 terminal species that span the geographic, ecological and taxonomic diversity of Alpheus. Our resulting, well-supported phylogeny demonstrates a lack of monophyly for five out of seven morphologically defined species groups that have traditionally been used as a framework in Alpheus taxonomy. Our results also suggest that symbiotic associations with a variety of other animals have evolved independently in at least seven lineages in this genus. Our AHE phylogeny represents the most comprehensive phylogenetic treatment of Alpheus to date and will provide a useful evolutionary framework to further investigate questions, such as various modifications of the snapping claw and the role of habitat specialization and symbiosis in promoting speciation.Running head: PHYLOGENY OF THE SNAPPING SHRIMP GENUS ALPHEUS.

On two new deep-water snapping shrimps from the Indo-West Pacific (Decapoda: Alpheidae: Alpheus).

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.

Description of Alpheus gallicus, a new deep-water snapping shrimp from Galicia Bank, northeastern Atlantic (Malacostraca, Decapoda, Alpheidae).

A new species of the snapping shrimp genus Alpheus Fabricius, 1798 is described based on material from Galicia Bank, an offshore seamount off northwestern Spain. The type series of Alpheus gallicus n. sp. was collected at a depth of 768-785 m, making it one of the deepest occurring snapping shrimps. The new species belongs to the Alpheus macrocheles species group and is morphologically most similar to several deep-water members of this group, viz. A. lentiginosus Anker Nizinski, 2011, A. platydactylus Coutière, 1897, A. romensky Burukovsky, 1990, as well as to the shallow-water A. macrocheles (Hailstone, 1835). The new species can be distinguished from all of them by some features on the minor cheliped and dactyli of the third to fifth pereiopods. In addition to morphology, DNA barcoding of the COI gene distinguished A. gallicus n. sp. from all related species with available barcode sequences.

The complete mitochondrial genome of Alpheus hoplocheles (Decapoda: Alpheidae)

The snapping shrimp genus Alpheus is the most diverse and abundant genus of Caridea. However, the phylogenetic and taxonomic studies have so far been limited. In this study, we report the third complete mitochondrial genome of Alpheus from A. hoplocheles. The mitogenome has 15,735 base pairs (60.2% A + T content) and made up of a total of 37 genes (13 protein-coding, 22 transfer RNAs and 2 ribosomal RNAs), and a control region. This study was the third available complete mitogenomes of Alpheidae and will provide useful genetic information for future phylogenetic and taxonomic classification of Alpheidae.

A new deep-sea species of the snapping shrimp genus Alpheus Fabricius, 1798 (Decapoda: Caridea: Alpheidae) from Kagoshima Bay, Japan.

A new species of the snapping shrimp genus Alpheus Fabricius, 1798, A. longipalma, is described and illustrated on the basis of material from Kagoshima Bay, Kyushu, Japan. It is referred to the A. brevirostris (Olivier, 1811) species group, and appears closest to A. macroskeles Alcock Anderson, 1894, known with certainty from the Bay of Bengal and Andaman Sea, and A. talismani Coutière, 1898 from the eastern Atlantic. The greatly elongate minor cheliped in males, being subequal to or longer than the major cheliped with proportionally shorter dactylus distinguish the new species from A. macroskeles. The less elongate antennular peduncle and better-developed, rounded distal lamella of the antennal scaphocerite differentiate the new species from A. talismani. All specimens of the new species were trawled from depths greater than 200 m.

A new species of the snapping shrimp genus Alpheus (Crustacea: Decapoda: Caridea: Alpheidae) from Japan, associated with the innkeeper worm Ikedosoma elegans (Annelida: Echiura: Echiuridae).

A new species of the snapping shrimp genus Alpheus Fabricius, 1798, Alpheus ikedosoma, is described and illustrated on the basis of material from Boso Peninsula and Ariake Sea, Japan. All examined specimens were extracted with the help of a bait suction pump from burrows of innkeeper worm (Annelida: Echiura), constructed on easily accessible intertidal sand beaches or sand flats. The host worm from Boso Peninsula was identified as Ikedosoma elegans (Ikeda, 1904) (Echiuridae). The new species is tentatively referred to the A. brevirostris (Olivier, 1811) species group, but it is characteristic in having several unusual features for the group, such as the very short rostrum without dorsal ridge, the absence of adrostral grooves on the carapace, the strongly reduced dorsolateral spines on the telson, the unarmed antennal basicerite, the non-elongate, almost glabrous major chela, and the lack of movable spines or spinules on ventromesial margin of each cheliped merus. The new species represents the sixth species of Alpheus associated with echiuran burrows.

Description of a new deep-water species of Alpheus Fabricius, 1798 from the Gulf of Mexico (Crustacea, Decapoda, Alpheidae)

A new deep-water species of the snapping shrimp genus Alpheus Fabricius, 1798 is described from two offshore localities in the northern Gulf of Mexico, south of Louisiana. Alpheus lentiginosus n. sp. belongs to the A. macrocheles (Hailstone, 1835) species group and is most closely related to the western Atlantic A. pouang Christoffersen, 1979 and A. amblyonyx Chace 1972, the eastern Atlantic A. platydactylus Coutière, 1897 and A. macrocheles (Hailstone, 1835), and perhaps also to the eastern Pacific A. exilis Kim & Abele, 1988. The new species is associated with deep-water soft sediments adjacent to clusters of Lophelia pertusa (L.) (Scleractinia) or mud-covered rocks and cobble, at a depth range of 336–438 m, thus representing the deepest-known record of the Alpheidae in the Gulf of Mexico and the entire western Atlantic.

On two snapping shrimps, Alpheus baccheti n. sp. and A. coetivensis Coutière from the Tuamotu Islands, French Polynesia (Crustacea, Decapoda)

The present study deals with two species of the snapping shrimp genus Alpheus Fabricius, 1798 recently collected on a shallow reef flat of Makemo, central Tuamotu Islands, French Polynesia. Alpheus baccheti n. sp., is described on the basis of a single complete male specimen (holotype). The new species appears to be most closely related to the species of the A. lobidens de Haan, 1849 and A. strenuus Dana, 1852 species complexes, but can be easily distinguished from all of them by the presence of a distoventral tooth on the merus of the third and fourth pereiopods. The presence of Alpheus coetivensis Coutière, 1908 in the Tuamotu Islands is confirmed on the basis of several specimens from Makemo; some taxonomic remarks are provided for this species. The diagnostic colour patterns are illustrated for both A. baccheti n. sp. and A. coetivensis.

Molecular phylogeny reveals extensive ancient and ongoing radiations in a snapping shrimp species complex (Crustacea, Alpheidae, Alpheus armillatus)

Tropical marine habitats often harbor high biodiversity, including many cryptic taxa. Though the prevalence of cryptic marine taxa is well known, the evolutionary histories of these groups remain poorly understood. The snapping shrimp genus Alpheus is a good model for such investigations, as cryptic species complexes are very common, indicating widespread genetic diversification with little or no morphological change. Here, we present an extensive phylogeographic investigation of the diversified amphi-American Alpheus armillatus species complex, with geographic sampling in the Caribbean Sea, Gulf of Mexico, Florida, Brazil, and the tropical Eastern Pacific. Sequence data from two mitochondrial genes (16SrRNA and cytochrome oxidase I) and one nuclear gene (myosin heavy chain) provide strong evidence for division of the species complex into six major clades, with extensive substructure within each clade. Our total data set suggests that the A. armillatus complex includes no less than 19 putative divergent lineages, 11 in the Western Atlantic and 8 in the Eastern Pacific. Estimates of divergence times from Bayesian analyses indicate that the radiation of the species complex began ∼10 MYA with the most recent divergences among subclades dating to within the last 3 MY. Furthermore, individuals from the six major clades had broadly overlapping geographic distributions, which may reflect secondary contact among previously isolated lineages, and have apparently undergone several changes in superficial coloration, which is typically the most pronounced phenotypic character distinguishing lineages. In addition, the extensive substructure within clades indicates a great deal of molecular diversification following the rise of the Isthmus of Panama. In summary, this investigation reflects substantial biodiversity concealed by morphological similarity, and suggests that both ancient and ongoing divergences have contributed to the generation of this biodiversity. It also underlines the necessity to work with the most complete data set possible, which includes comprehensive and wide-ranging sampling of taxa.

A MULTILOCUS TEST OF SIMULTANEOUS DIVERGENCE ACROSS THE ISTHMUS OF PANAMA USING SNAPPING SHRIMP IN THE GENUSALPHEUS

The completion of the Panamanian Isthmus is one of the greatest natural experiments in evolution, sending multiple species pairs from a broad range of taxonomic groups on independent evolutionary trajectories. The resulting transisthmian sister species have been used as model systems for examining consequences that accompany cessation of gene flow in formerly panmictic populations. However, variance in pairwise genetic distances of these "geminates" often exceeds expectations, seemingly conflicting with the assumption that separation of populations was contemporaneous with the final closure of the Isthmus. Multilocus datasets and coalescent-based analytical methods can be used to estimate divergence times while accounting for variance in gene divergence that predates isolation, thus removing the need to invoke unequal divergence times. Here we present results from Bayesian analyses of sequence data from seven nuclear and one mitochondrial marker in eight transisthmian species pairs in the snapping shrimp genus Alpheus. Divergence times in two species pairs were shown to occur much earlier than the Isthmus final closure, but much of the variance in pairwise genetic distances from cytochrome oxidase I (COI) was explained when ancestral polymorphisms were accounted for. Results illustrate how coalescent approaches may be more appropriate for dating recent divergences than for estimating ancient speciation events.

Color Photographs for Morphological and Developmental Differences in Three Species of the Snapping Shrimp Genus Alpheus (Crustacea, Decapoda)

Abstract Living, freshly collected individuals of three species of snapping shrimps were studied to determine any differing morphological, developmental, and ecological features: Alpheus heterochaelis, collected from Beaufort, NC; A. angulosus, found mainly in Jacksonville, FL, but also at one site in Beaufort; and A. estuariensis, collected at another Jacksonville site. Structural characteristics of these superficially similar species are summarized, with particular attention to coloration. Adult A. angulosus individuals have blue-green 2nd antennal flagella (vs. tan in the other two species) that are significantly shorter than those of A. heterochaelis. Alpheus angulosus and A. estuariensis bear smaller eggs ( 1 mm), and the former species displays the zoea larval form typical of alpheids (vs. abbreviated larval development in A. heterochaelis).

Morphological and Developmental Differences in Three Species of the Snapping Shrimp Genus Alpheus (Crustacea, Decapoda)

Abstract Living, freshly collected individuals of three species of snapping shrimps were studied to determine any differing morphological, developmental, and ecological features: Alpheus heterochaelis, collected from Beaufort, NC; A. angulosus, found mainly in Jacksonville, FL, but also at one site in Beaufort; and A. estuariensis, collected at another Jacksonville site. Structural characteristics of these superficially similar species are summarized, with particular attention to coloration. Adult A. angulosus individuals have blue-green 2nd antennal fl agella (vs. tan in the other two species) that are significantly shorter than those of A. heterochaelis. Alpheus angulosus and A. estuariensis bear smaller eggs ( 1 mm), and the former species displays the zoea larval form typical of alpheids (vs. abbreviated larval development in A. heterochaelis).

Evidence for Three Major Clades within the Snapping Shrimp Genus Alpheus Inferred from Nuclear and Mitochondrial Gene Sequence Data

The snapping shrimp genus Alpheus is among the most diverse of caridean shrimps, and analyses of taxa separated by the Isthmus of Panama have been used to estimate rates of molecular evolution. Although seven morphological groups have been informally suggested, no formal phylogenetic analysis of the genus has been previously attempted. Here we infer the phylogenetic relationships within Alpheus using sequence data from two nuclear genes, glucose-6-phosphate isomerase and elongation factor-1α, and from the mitochondrial gene cytochrome oxidase I. Three major clades corresponding to previously noted morphological features were identified. Discrepancies between earlier informal morphological groupings and molecular analyses largely consisted of species whose morphologies were not entirely typical of the group to which they had been assigned. The traditional placements of shrimp with highly sessile lifestyles and consequently simplified morphologies were also not supported by molecular analyses. Phylogenies for Alpheus suggest that specialized ecological requirements (e.g., symbiotic associations and estuarine habitats) and modified claw morphologies have evolved independently several times. These new analyses also support the sister species status of transisthmian pairs analyzed previously, although very similar pairs were not always resolved with the more slowly evolving nuclear loci. In addition, six new cryptic species were identified in the course of these studies plus a seventh whose status remains to be determined.

Mitochondrial pseudogenes are pervasive and often insidious in the snapping shrimp genus Alpheus.

Here we show that multiple DNA sequences, similar to the mitochondrial cytochrome oxidase I (COI) gene, occur within single individuals in at least 10 species of the snapping shrimp genus Alpheus. Cloning of amplified products revealed the presence of copies that differed in length and (more frequently) in base substitutions. Although multiple copies were amplified in individual shrimp from total genomic DNA (gDNA), only one sequence was amplified from cDNA. These results are best explained by the presence of nonfunctional duplications of a portion of the mtDNA, probably located in the nuclear genome, since transfer into the nuclear gene would render the COI gene nonfunctional due to differences in the nuclear and mitochondrial genetic codes. Analysis of codon variation suggests that there have been 21 independent transfer events in the 10 species examined. Within a single animal, differences between the sequences of these pseudogenes ranged from 0.2% to 20.6%, and those between the real mtDNA and pseudogene sequences ranged from 0.2% to 18.8% (uncorrected). The large number of integration events and the large range of divergences between pseudogenes and mtDNA sequences suggest that genetic material has been repeatedly transferred from the mtDNA to the nuclear genome of snapping shrimp. Unrecognized pseudogenes in phylogenetic or population studies may result in spurious results, although previous estimates of rates of molecular evolution based on Alpheus sister taxa separated by the Isthmus of Panama appear to remain valid. Especially worrisome for researchers are those pseudogenes that are not obviously recognizable as such. An effective solution may be to amplify transcribed copies of protein-coding mitochondrial genes from cDNA rather than using genomic DNA.

The snapping shrimp genus Alpheus from the eastern Pacific (Decapoda, Caridea, Alpheidae)

The snapping shrimp genus Alpheus from the eastern Pacific (Decapoda, Caridea, Alpheidae)