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"Calanoida"
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Sipadantoniusroihani gen. et sp. nov., a new genus and species of Pseudocyclopidae Giesbrecht, 1893 (Copepoda, Calanoida) from the marine cave \Turtle Tomb\ of Sipadan Island, Sabah, Malaysia
A new genus and species of the family Pseudocyclopidae,
, was described based on specimens collected using a light trap in the marine cave of Sipadan Island, Sabah, Malaysia. The new genus is most related to
, primarily based on the similarity observed in the armament of ancestral segment IV of the male antennules, the armament of the female P5 Exp-3, the segmentation of the male P5, the armament of the maxillular basal exite, and the relative length of the ancestral segment XXVII of the antennules. Nevertheless, it distinguishes itself from
and all other genera of the family by the absence of the lateral seta of the basis of all swimming legs, the presence of an inner seta on the coxa of the female P5, the reduction of furcal setae I and III, as well as the specific armament of the ancestral segment XX of the antennules and the maxillular coxal endite. The female of
has aesthetascs on the ancestral segments IV and XX of the antennules, as well as six setae on the maxillular coxal endite, exhibiting the most plesiomorphic characteristics of the family Pseudocyclopidae. The latter characteristic has not been recorded in the order Calanoida. It was hypothesised that the new species was a particle feeder living in the pelagic zone of the marine cave. The existence of the new species supported the assumption that the regional distribution of the family Pseudocyclopidae exhibited the Tethyan track, which might have been the subsequent result of the colonisation of the habitats prior to the closure of the Tethys Sea.
Journal Article
Molecular Phylogeny and Revision of Copepod Orders (Crustacea: Copepoda)
For the first time, the phylogenetic relationships between representatives of all 10 copepod orders have been investigated using 28S and 18S rRNA, Histone H3 protein and COI mtDNA. The monophyly of Copepoda (including Platycopioida Fosshagen, 1985) is demonstrated for the first time using molecular data. Maxillopoda is rejected, as it is a polyphyletic group. The monophyly of the major subgroups of Copepoda, including Progymnoplea Lang, 1948 (=Platycopioida); Neocopepoda Huys and Boxshall, 1991; Gymnoplea Giesbrecht, 1892 (=Calanoida Sars, 1903); and Podoplea Giesbrecht, 1892, are supported in this study. Seven copepod orders are monophyletic, including Platycopioida, Calanoida, Misophrioida Gurney, 1933; Monstrilloida Sars, 1901; Siphonostomatoida Burmeister, 1834; Gelyelloida Huys, 1988; and Mormonilloida Boxshall, 1979. Misophrioida (=Propodoplea Lang, 1948) is the most basal Podoplean order. The order Cyclopoida Burmeister, 1835, is paraphyletic and now encompasses Poecilostomatoida Thorell, 1859, as a sister to the family Schminkepinellidae Martinez Arbizu, 2006. Within Harpacticoida Sars, 1903, both sections, Polyarthra Lang, 1948, and Oligoarthra Lang, 1948, are monophyletic, but not sister groups. The order Canuelloida is proposed while maintaining the order Harpacticoida s. str. (Oligoarthra). Cyclopoida, Harpacticoida and Cyclopinidae are redefined, while Canuelloida ordo. nov., Smirnovipinidae fam. nov. and Cyclopicinidae fam. nov are proposed as new taxa.
Journal Article
The vertical distribution and abundance of copepod nauplii and other micro- and mesozooplankton in the seasonal ice zone of Luetzow-Holm Bay during austral summer 2009
The Antarctic seasonal ice zone (SIZ) is an ecologically important region of the Southern Ocean. However, the abundance and vertical distribution of micro- and mesozooplankton in this zone, in particular the contribution of nauplii of smaller copepod taxa, are poorly understood. We investigated the vertical distribution, abundance, and species composition of micro- and mesozooplankton in the SIZ of Luetzow-Holm Bay, East Antarctica, in January 2009. Zooplankton samples were collected using a 60- mu m mesh closing net (appropriate to estimate the quantitative abundance of copepod nauplii) vertically hauled from three depth layers (0-100, 100-200, 200-500 m). Small calanoid copepods, Oithonidae, and Oncaeidae were dominant among the zooplankton communities in this region. Cluster analysis revealed that the communities were separated by depth into epipelagic (0-200 m) and mesopelagic (>200 m) groups. Distribution patterns in the 0- to 100-m layer changed at the sea ice edge, but showed no clear relationship with frontal structures. Nauplii of copepods including Oithona spp., Oncaea spp., and Calanoida were major contributors to total zooplankton abundance. The abundance of these nauplii in the surface layer was high in open water and the marginal ice zone but low in the pack ice zone where chlorophyll a concentrations were high. Low water temperature associated with sea ice, rather than food availability, may have caused the low copepod nauplii abundance observed in the surface layer within the pack ice zone. These findings provide valuable background information to monitor variations in zooplankton community structure in response to changing environmental conditions.
Journal Article
Geography, ecology, and history synergistically shape across-range genetic variation in a calanoid copepod endemic to the north-eastern Oriental
The center-periphery hypothesis (CPH) predicts that peripheral populations will have lower genetic variation than those at the center of a species’ distribution. However, ecological margins do not always coincide with geographical edges when topographies are diverse. Historical climate changes can also strongly affect genetic variation. Here, we examined genetic variation in Phyllodiaptomus tunguidus, a calanoid copepod endemic to the north-eastern Oriental. This species was predicted to exhibit a complex pattern of genetic variation across its range due to the diverse topographies and stable climate history of the north-eastern Oriental. To test this, we used geographic distance to the center of the distribution, current ecological suitability, and climate during the last glacial maximum as geographical, ecological, and historical factors, respectively, in our analyses. We measured genetic diversity and population differentiation using mitochondrial and nuclear markers. This showed that P. tunguidus had 3 refugia during the last glacial maximum (LGM). Such a pattern of multiple refugia complicates the determination of the center and periphery of spatial genetic diversity. Both regression models and redundancy analyses failed to support the CPH. Instead, they showed that geographical, ecological, and historical factors together shaped population genetic structure in this species. Ecological factors explained significantly more genetic variation than did geographical and historical factors—however, all three factors interacted significantly to affect the pattern of genetic variation. The results extend our understanding of the CPH and the extent to which it can explain genetic variation across populations.
Journal Article
Zooplankton-associated Bacterial Communities are Dominated by Host-Specific Rather than Environmentally Random Taxa
Zooplankton-associated bacteria (ZA) are critical to freshwater ecosystems and host health, but their assembly mechanisms and core microbiota remain poorly understood. We surveyed lakes across different altitudes in China and collected Calanoida, applying gut-emptying treatments to obtain ZA and fecal bacteria (FB). In parallel, free-living (FL) and particle-attached bacteria (PA) were sampled from waters. All bacterial communities were analyzed using 16S rRNA amplicon sequencing to compare community structures and infer potential sources of ZA. Our results showed that ZA showed lower diversity and a distinct structure compared with FB, FL, and PA, while the latter three were relatively similar. Moreover, deterministic processes dominated ZA assembly, with their influence strengthening at higher altitudes, as reflected by decreasing MST values. Core microbiota analysis revealed 31 genera consistently present in ZA. Six of these (
Pseudoalteromonas
,
Aeromonas
,
Streptococcus
,
Vibrio
,
Lactococcus
, and
Shewanella
) were predominantly enriched, suggesting a stable and host-associated core microbiota, with
Pseudoalteromonas
and
Vibrio
showing marked enrichment in high-altitude lakes. Source tracking further revealed that an average of over 70% of ZA could not be assigned to FL or PA, suggesting that most ZA members did not originate directly from environmental bacterial pools. These findings indicate that ZA are not randomly assembled from environmental bacteria but include a consistent core shared by most hosts. Our study demonstrates that zooplankton maintain specific and stable bacterial communities and, by comparing ZA, FB, FL, and PA across an altitudinal gradient, provides new insights into their assembly mechanisms and ecological roles in freshwater ecosystems.
Journal Article
Two new species of Tortanus (Atortus) (Copepoda, Calanoida, Tortanidae) from the Andaman Islands
Two new species of the planktonic copepod genus Tortanus, subgenus Atortus, are described from inter- to sub-tidal water of South Andaman Island, India. The new species are assigned to the tropicus group sensu Othman (1987) and distinguished from the other members of the group by the characteristic morphology of the pair of posterior dorsolateral processes on the fifth pedigerous somite in the female and the antennule and leg 5 in the male. An analysis of previous records of the tropicus species group indicates their sporadic occurrence combined with high species richness in Southeast Asia, suggesting future discovery of even more species by sampling with finer geographic and habitat coverage.
Journal Article
Biodiversity of Calanoida Copepoda in Different Habitats of the North-Western Red Sea (Hurghada Shelf)
Little is known about the diversity of Calanoida, Copepoda, in different habitats of the north-western Red Sea. In this study, biodiversity of Calanoida, Copepoda, during the cold and warm seasons of 2017, were observed at 12 stations belonging to four different habitats (coral reef (CR), sheltered shallow lagoons (SSL), seagrass (SG), and open deep-water (ODW) habitats) in the Hurghada shelf, north-western Red Sea. SSL habitats were the most affected by environmental conditions, especially temperature, salinity, and depth. Some calanoid species were restricted to certain habitats, others were adapted to live in more than one habitat, while some species showed a wide distribution in all habitats. ODW habitats showed maximum diversity and density of the calanoid species. The effects of temperature and salinity were distinct in the SG and SSL. The results clearly showed that different Red Sea habitats affected the biodiversity of calanoid copepods.
Journal Article
Phylogeography and genetic diversity of some Sinocalanus species (Copepoda, Calanoida, Centropagidae) detected in inland and estuarine waters of China
Abstract
In spite of the important ecological roles of copepods, their phylogeny and taxonomy remain largely unexplored in China. Here, we investigated the taxonomy and diversity of some Sinocalanus species (Copepoda, Calanoida, Centropagidae) in China. We observed two morphospecies (S. tenellus and S. doerrii) from this genus in 42 of 636 Chinese waterbodies examined. Molecular phylogenies inferred from a mitochondrial (mitochondrial cytochrome c oxidase subunit I; COI) and a nuclear marker (the nuclear 18S ribosomal RNA gene; 18S) verified the identities of these species and allowed us to amend previous misidentifications. Pronounced ecological separation between the two Sinocalanus species detected was found: S. doerrii inhabited freshwaters and was widely distributed across China, whereas S. tenellus was mainly found in brackish estuaries. One clade of S. doerrii had been misidentified (based on molecular data only) as S. tenellus in previous works, with consequent mislabeling of the sequences uploaded to GenBank. Additionally, we detected a new mitochondrial lineage of S. tenellus, most frequently in Jiaozhou Bay, China, whereas its sibling lineage was distributed in estuaries along the coasts of the East China Sea. Our study contributes to understanding the taxonomy and genetic diversity of the genus Sinocalanus in Chinese freshwater and brackish-water ecosystems.
Journal Article