Abstract The recently described alpheid species Potamalpheops yamakawai Yamashita, Komai & Koreeda, 2024 is reported from Taiwan for the first time, with the identification confirmed by DNA barcoding of the 16S gene. The characteristics of the Taiwanese material are described and illustrated, together with colour photographs.
Abstract The family Epialtidae is the most species-rich lineage within the superfamily Majoidea, but complete mitochondrial genomes (mitogenomes) have been reported for only a few of its members. In this study, we sequenced the complete mitogenome of the decorator crab Hyastens ducator using next-generation high-throughput sequencing, annotated its mitochondrial genes and analysed its genomic organisation. The complete mitogenome of H. ducator is 15 894 bp in length and contains 37 genes, including 13 protein-coding genes (PCGs), two ribosomal RNA genes and 22 transfer RNA genes. The tRNAs range from 52 to 74 bp in length. The nucleotide composition of the complete mitogenome is 34.9% A, 18.2% C, 9.4% G and 37.5% T. A comparison of gene order among species within Majoidea shows that the overall gene order of mitogenomes is largely conserved, but the positions of some short genes and non-coding regions vary to different degrees. Most changes occur in transfer RNA regions and gene orders ranged from highly conserved to extensively rearranged among different lineages. Phylogenetic analyses based on the 13 PCGs robustly placed H. ducator within Epialtidae, clustered it with other epialtid species with strong support and provided new molecular evidence for relationships among families and genera within Majoidea. Overall, this study reports the mitogenome of H. ducator for the first time, clarifies its phylogenetic position, enriches the molecular dataset for the family Epialtidae and provides an important reference for future taxonomic and evolutionary studies of Majoidea.
Abstract Mimetic colouration is a widespread survival strategy that allows organisms to reduce predation by blending into their environment through adaptations in colour, texture, or shape. Symbiotic crustaceans are no exception and frequently exhibit host-specific morphological traits, including mimetic pigmentation. In some cases, however, ecological pressures force symbionts to switch hosts. When the new host exhibits a different chromotype (i.e., colour morphotype), the symbiont may adjust its colouration accordingly to maintain effective camouflage. This study investigates whether the symbiotic shrimp Zenopontonia soror can adapt its colouration to that of its host sea star, Culcita novaeguineae . An experimental host chromotype switch was conducted, and changes in shrimp colouration were monitored over a 12-day period using a standardized photography protocol. To explore potential pigment acquisition pathways, the diet of the symbiotic pair was examined through direct observation of the stomach contents using optical and scanning electron microscopy, complemented by stable isotope ratio analyses. The results demonstrate a clear chromatic adaptation of the symbiont to its new host following the host switch: yellow shrimp individuals progressively acquired the purple colouration of their new host within 12 days. Stable isotope data and stomach content analyses both indicate food sharing and direct feeding on host tegument by the symbiont. These results suggest that Z. soror could acquire pigments from its host by consuming its tissues and stealing some of its food intake, which would allow colour adaptation and question its symbiotic status as a commensal.
Abstract Meteoronia gen. nov. is established here to accommodate two new species of bivalve-associated palaemonid shrimps, described from the deep-waters of the tropical eastern Atlantic Ocean. The new genus is characterised by a laterally compressed rostrum distally armed with dorsal and ventral teeth; the carapace lacking supraorbital, hepatic or epigastric teeth, but armed with an antennal tooth; the sixth pleonite posteriorly unarmed; the first pereiopod chelae with simple fingers; the second pereiopods unequal in size, highly dissimilar in shape, with the major chela palm with a distodorsal transverse groove, and the dactylus armed with two strong triangular teeth in proximal half; and the ambulatory pereiopods each ending in an elongate, slender, simple dactylus. Meteoronia gen. nov. does not seem to present any autapomorphic feature immediately distinguishing it from other palaemonid genera, however, the unique combination of several diagnostic morphological characters, together with its host association, strongly corroborate its recognition as a new genus. Meteoronia hovingi sp. nov. and Meteoronia sarahbruckae sp. nov., described below, are very similar in their overall morphology but can be distinguished by several details in the rostrum shape and armature, as well as by differences in their cephalic and thoracic appendages.
Abstract A new species of the thorid genus Lebbeus White, 1846, Lebbeus flammeus , is described based on two specimens collected from the Nemuro Strait, located at the southwestern part of the Sea of Okhotsk, Hokkaido, Japan, at bathyal depths of 525-825 m. The species status was assessed through combining morphological comparison and phylogenetic analyses using nucleotide sequences of the mitochondrial COI and 16S rRNA genes. The new species is morphologically most similar to L. longipes (Kobjakova, 1936) known from the Sea of Japan, but differs in having more numerous dorsolateral spiniform setae on the telson, a shorter antennular stylocerite not reaching the distal margin of the first peduncular article, and a darker live colouration. The discovery of this new species raises the number of the species of Lebbeus known from East Asian waters to 41.
Abstract Two species of shrimps in the genus Processa Leach, 1815 are reported from the Indian River and Lake Worth lagoons on the Atlantic coast of Florida, U.S.A. Both species were collected from the burrows of unknown macroinvertebrate hosts. Processa vossi Manning, 1992 is a potentially obligate burrow cohabitant and is reported for the first time since its original description. Processa hemphilli Manning & Chace, 1971 is a generalist species that is reported for the first time in association with burrows.
The aim of this study was to investigate the diversity of Amphipoda (Crustacea) in two mediterranean marine habitats with different degrees of human influence. Samples were collected in the Marine Protected Area (MPA) of Brijuni National Park (Croatia) as well as from biofouling on the pillars of five gas platforms in the northern Adriatic Sea. A species list for both areas is provided and the Shannon diversity indices, as well as the frequency of occurrence and relative abundance for each species were calculated. In the MPA, a total of 46 amphipod species were identified, including six species endemic to the Mediterranean (Ampithoe riedli, Autonoe rubromaculatus, Leptocheirus cf. mariae, Ampelisca cf. ledoyeri, Iphimedia vicina and Lysianella dellavallei). Only one species, Caprella scaura, was classified as recently introduced. In contrast, four amphipod species were recorded in the artificial habitat of the gas platforms, all of which were classified as either alien (Jassa slatteryi, Stenothoe georgiana) or cryptogenic, meaning of unclear origin (Elasmopus rapax, Stenothoe valida). Brijuni MPA had a higher Shannon index, while the relative abundance of most species was low compared to the artificial habitat. Calculated species accumulation curves and estimators indicate even higher diversity. The findings of this study highlight the importance of marine protected areas in safeguarding local fauna and preserving native and endemic species. They also demonstrate how artificial structures in marine ecosystems can facilitate the introduction, establishment, and potential mass proliferation of non-indigenous species (NIS).
In the genus Physocypria V & aacute;vra, 1897, as in many freshwater ostracods without prominent carapace ornamentation and with conservative appendage morphology, typological taxonomy led to an underestimation of biological diversity and notion of widely distributed species with significant morphological variability. Molecular studies, in combination with linear morphometrics, revealed some members in East Asia to be species complexes, but did not lead to formal descriptions, as is often the case with research on cryptic species. Here we combine macro-morphological taxonomy with a phylogenetic study of two mitochondrial genes (COI and CytB) and landmarkbased geometric morphometrics (LBGM) of the carapace and two appendages on Korean and Japanese members of this genus, with P. kraepelini M & uuml;ller, 1903 from Germany as an outgroup. Two new species are described: P. hyunsuyooi n. sp. from Korea and P. smithi n. sp. from the ancient Lake Biwa in Japan. We confirm the validity of the Japanese P. nipponica Okubo, 1990 and challenge the Palearctic distribution of P. kraepelini, and its presence in East Asia. The Japanese P. biwaensis (Okubo, 1990) was detected with molecular tools in Korea and China, which is its first record outside Lake Biwa. Principal Component Analysis of the carapace resulted in a clear morphospace clustering of species, but appendages prove impractical for LBGM species delineation. Species living in sympatry differ significantly in centroid size, suggesting size differentiation as an evolutionary mechanism. Despite high variability in male sexual characteristics within the genus, fine details of the morphology of the hemipenis, prehensile palps, and male second antenna may prove useful for distinguishing some species, highlighting the importance of fresh interpretation of morphological characters. Like in many other small invertebrates, integrative taxonomy was crucial for resolving species complexes, as no single method was sufficient for delineation of all five Physocypria species.
Fishery management strategies for marine organisms are based on the definition of management units. Currently, very little is understood about the seasonal spatial distribution pattern and possible migration of southern rough shrimp Trachysalambria curvirostris (Stimpson, 1860) in the southern Yellow and East China Seas, which is also of commercial importance to small-scale bottom seiners and trawlers across its native distribution range. In this study, we employed independent scientific trawling surveys (26.50-35.00 degrees N 120.00-127.00 degrees E) in 2018-2019 and ensemble models to understand the contemporary seasonal distribution patterns, as well as projecting potential responses to climate change in T. curvirostris. Annual mean biomass and abundance values were 9933 +/- 7776 g/h and 2531 +/- 2398 ind/h. The total biomass and abundance reached their peak in autumn, followed by summer and spring, and were lowest in winter. With regard to migration route, we suggest that Lianqingshi and Dasha fishing grounds are the nursery and overwintering grounds for the Yellow-Bohai Sea population across the season, and Zhoushan-Yushan and Zhouwai fishing grounds are important spawning and overwintering grounds for the East China Sea population. Juveniles in summer were concentrated in the shallow coastal water of Zhoushan islands with a sea bottom temperature of 24-25 degrees C and salinity of 31-32. Trachysalambria curvirostris was found at depths of 20-120 m across the season. Various climate scenarios could assert a key impact on the habitat range of T. curvirostris. Our findings provide baseline information for fishery management strategies, supporting the sustainable development of T. curvirostris fisheries.
This study evaluated the effects of dietary sodium butyrate on growth performance, feedutilization, immune responses, and antioxidant capacity inPenaeus vannamei. Post-larvae (PL10)were fed diets with 1, 2 and 3% sodium butyrate, as well as a control diet, for 120 days. Shrimpfed with 2% sodium butyrate diet achieved the highest final weight (14.71 +/- 0.08 g), weightgain (1.94 +/- 0.08 g), specific growth rate (3.66 +/- 0.17%), survival rate (88.88 +/- 3.85%), anda better feed conversion ratio (1.34 +/- 0.12) compared to the control and other treatment groups.Immunological assessments showed increased cellular and humoral responses, including totalhaemocyte counts (46.74 & times;106cells/ml), granulocyte (28.35 & times;106cells/ml) and hyaline cell counts(19.42 & times;106cells/ml), serum protein (86.69 +/- 3.02 mg/ml), lysozyme activity (1.12 +/- 0.06 U/ml),and prophenoloxidase activity (0.78 +/- 0.05 OD at 490 nm). Antioxidant capacity, measured bysuperoxide dismutase activity (8.5 +/- 0.04 mu mol), was also higher in shrimp fed with 2% butyrate.These findings show that adding 2% sodium butyrate per kg of feed facilitates optimizing growth,immunity, and stress tolerance inP. vannamei. Sodium butyrate can be a useful feed additive forsustainable shrimp farming, improving health, productivity, and disease resistance.
The palaemonid shrimp genus Palaemonella Dana, 1852 is currently represented by 38 species from the world oceans, of them 33 species occur in the Indo-West Pacific. In this study, a new species, Palaemonella rufidigitata, is described based on a single male specimen from Okinawa Island, the Ryukyu Islands, Japan. It is morphologically very similar to P. okunoi Komai & Yamada, 2015, from which it is distinguishable by the more posteriorly located epigastric tooth on the carapace, a less produced distolateral tooth of the antennal scaphocerite (not overreaching the lamella), the absence of a row of spiniform setae on the distoventral margin of the third maxilliped ischio-merus, and a distinct colour pattern of the second pereopod fingers (reddish in the new species as opposed to the absence of color in P. okunoi). The holotype was collected from beneath coral rock at a depth of 10 m, with no evidence of symbiotic association. Phylogenetic analysis utilizing the mitochondrial 16S rRNA gene indicates that P. rufidigitata spec. nov. is genetically rather remote from P. okunoi but proximate to P. nudirostris Marin, 2014, and P. aliska Marin, 2008, although the new species exhibits notable morphological dissimilarities with the latter two species.
The ectosymbiont fauna associated with crustaceans in South American inland waters is characterized by a marked microendemism, as the species concerned appear to show high host specificity. The aim of the present study is to present a review of ciliated Protozoa reported as ectosymbionts on South American inland water malacostracans. The literature revealed the existence of three genera, Chilenophrys with one species, Lagenophrys with five species, and Operculigera with seven species. The main limiting factor is that many species descriptions require further validation, as the reports have not been confirmed. The literature reports the presence of Lagenophrys lenticulata associated with Hyalella curvispina from Uruguay. H. curvispina is widespread throughout southern South America, including Argentina and Chile, and it may be possible to find epibionts on other populations of H. curvispina , as well as on other Hyalella populations. Lagenophrys aegleae has been recorded on the genus Aegla in eastern and western South America; L. antichos on crayfishes in east and west South America; and L. lenticulata on amphipods in North America and Uruguay. Ecological and biogeographical topics are also addressed.
The length-weight relationship (LWR) of the Pacific white leg shrimp Penaeus vannamei was evaluated using data collected during two periods within the same year from twelve earthen ponds at two commercial aquaculture farms located near the mouth of the Gulf of California. The farms differed in water source: marine, estuarine-freshwater, and estuarine-hypersaline. Five alternative models were fitted to the LWR, with parameters estimated using maximum likelihood. Model selection was conducted using the Bayesian Information Criterion. The two-segment model was most frequently selected (18 cases), whereas cubic and quadratic models were selected three times each. No consistent pattern in the allometric coefficient was observed among water sources or cultivation periods. These results indicate that water source and operational conditions can influence allometric growth in cultured shrimp. Incorporating variability in allometric responses may improve assessments of growth dynamics and contribute to more effective and sustainable shrimp aquaculture management.
The validity of two overlooked species names in the cymothoid genus Ichthyoxenos Herklots, 1870 (often misspelled Ichthyoxenus) from Chinese freshwater habitats are discussed in the context of the diversity of the genus and validity of the species therein. Ichthyoxenos is problematic as it contains 26 described species from both freshwater and marine habitats and several of the freshwater species were described from the same host in the same general locality in China and are likely synonyms. We briefly review selected species in the genus and discuss their status and the likelihood of the genus being monophyletic. We also replace the junior homonym, Ichthyoxenos yunnanensis Shen, 1940 with Ichthyoxenos sheni nom. nov. and transfer Lironeca enigmatica Fryer, 1968 into Ichthyoxenos.
A new species of cyclopoid copepod Apocyclops sakijangensis n. sp. (Copepoda: Cyclopidae) is described from St John's Island in the Singapore Strait. Morphological comparisons between the new species and 11 other congeners showed that A. sakijangensis n. sp. is distinct in having antennal endopodite with allobasis and two free segments, rounded medial expansion of basipodite on P2-P4, a single posterior row of spinules in intercoxal sclerite of P1, two posterior rows of spinules in the intercoxal sclerite of P2-P3, three posterior rows of spinules in the intercoxal sclerite of P4, clusters of spinules on the ventral and dorsal surface of the caudal ramus, and a line of spinules on the ventral surface of P5 extending medially. The new species is most similar to A. ramkhamhaengi described from brackish waters in southern Thailand but can be distinguished by the posterior ornamentation of the intercoxal sclerite in P2 and P3. In A. ramkhamhaengi only a single row of spinules is present on the posterior intercoxal sclerite of P2 and P3, whereas in the new species, there are two distinct rows. Genetically, A. sakijangensis n. sp. is distinguished from A. borneoensis (5.6%) and A. panamensis (10.2%) based on Kimura-2-parameter distance (K2P) values of the 28S gene. The new species can be cultured readily indoors (27-32 degrees C) in moderate densities (0.8-2.7 individuals/ml) in vessels up to 0.06 m3 in size at 29-30 psu on Baker's yeast (Saccharomyces cerevisiae). The composition of essential fatty acids in A. sakijangensis n. sp. was comparable to its congeners known from other studies.
Kellnerius jamacaruensis Santana, Pinheiro, Silva & Saraiva, 2013, a fossil caridean shrimp from the Cretaceous Araripe Basin, has been the subject of a recent redescription by Barros et al. (2025), and we herein provide a methodological and nomenclatural reassessment of Barros et al. (2025). We focus on three main issues: (1) the reinterpretation of a diagnostic groove on the third pleonal somite as a taphonomic artifact, which is contradicted by new high-resolution Scanning Electron Microscope imaging; (2) the application of chemical preparation techniques directly to the holotype; and (3) assertions regarding the nomenclatural status of the species under ICZN provisions and ZooBank registration. New SEM micrographs confirm the presence of the diagnostic groove, supporting the morphological basis for the original species description. We examine issues of taxonomic practice, including specimen conservation, institutional curation, and nomenclatural compliance, highlighting the need for rigorous standards in paleontological taxonomy, careful observation, transparent methodology, and responsible custodianship of scientific heritage.
The deeper-water palaemonid shrimp, Bathymenes aleator, is recorded for the first time from New Zealand waters. Comparative illustrations are provided, including for the first time the appendix masculina of the male.
Stalked barnacles are sessile crustaceans that attach to various marine organisms and drifting substrates. Among them, Alepas spp. (Cirripedia: Scalpellomorpha: Heteralepadidae) exhibit a highly specialised lifestyle by attaching to the marginal areas of the umbrella of large jellyfish species such as Cyanea nozakii and Diplulmaris malayensis, drifting along with their hosts. In this study, we observed the ecology of Alepas pacifica collected from Cyanea nozakii off the coast of Kushimoto and Shirahama, Wakayama Prefecture, Japan, and conducted molecular phylogenetic analyses. Field observations revealed that A. pacifica individuals were directly feeding on the host's tentacles, suggesting that they utilise host tissues as a nutritional resource. Molecular phylogenetic analyses further demonstrated that Alepas is included in the genus Conchoderma, which commonly attach to nektonic organisms such as sea snakes and fishes. Although Alepas has traditionally been classified within the Lepadidae based on morphological traits, such as the presence of filamentary appendages at the bases of multiple cirri, its phylogenetic position within the family has remained unclear. This uncertainty is likely due to adaptations to life on gelatinous zooplankton hosts, including the reduction of calcareous plates and increased body transparency. Our findings indicate that Alepas represents a lineage of barnacles that shifted its ecological association from commensalism with vertebrates to parasitism on planktonic jellyfish.
The decapod crustacean Barytelphusa cunicularis (Westwood in Sykes, 1836) (Gecarcinucidae) is among the world's largest freshwater crabs, with both ecological and economic significance. The crab species inhabits diverse aquatic habitats throughout peninsular India, including the Western Ghats. Although commensal associations between invertebrates (including crustaceans) and aquatic insects are widespread, no previous records exist of brachyurans hosting immature chironomids (Diptera: Chironomidae). This study documents the first commensal association between B. cunicularis (Brachyura) and chironomid larvae and pupae, based on field surveys during the dry season in the Kalsubai Harishchandragad Wildlife Sanctuary, Maharashtra. Of 28 crabs examined, 23 harboured chironomid larvae or pupae, most commonly occurring in their subbranchial region, especially in subadults with pre-existing exoskeletal deformities. No infestations were detected in crabs collected during the rainy season or among more terrestrial species, indicating strong seasonal and ecological specificity. Observed deformities in regions where larvae were present appeared to predate their occurrence and were likely related to moulting or environmental stress; there was no evidence that chironomid larvae caused further host damage, supporting a commensal, rather than parasitic, relationship. A potential benefit to the larvae may include passive transport via the host, although this requires further investigation. These findings expand the recognised host range of chironomids and underscore the ecological plasticity of this symbiosis, highlighting the need for further taxonomic and ecological investigation.
The mud shrimp genus Ctenocheles Kishinouye, 1926 is recorded from Taiwan for the first time. The species found is the rather rare C. balssi Kishinouye, 1926 and the identification is confirmed by DNA barcoding analysis. Description of the species and illustrations of the Taiwanese specimen are provided.
