FIGURE 11 - uploaded by Marina R. Cunha
Content may be subject to copyright.
Heteromesus ctenobasius sp. nov. Paratype female, AM P 72120: SEM micrographs, antennula; antenna, head ventral; maxillipeds; pereopod I. Scale bars 0.1mm.
Source publication
Sixteen species of Heteromesus Richardson are reviewed, additional terms are introduced to account for special morphologies in the Ischnomesidae, the diagnosis of the genus is updated and a key to species is given. Twelve species, which have previously been recorded from the Atlantic Ocean, are redescribed and four new species are described, H. cal...
Citations
... nov. (Fig. 8D), Joeropsididae and other janiroideans, it is positioned under the anterior margin of pereionite 5, either dorsally or laterally, whereas in Haploniscidae, similar to other deep-sea janiroideans (e.g., Ischnomesidae Hansen, 1916; see Cunha & Wilson 2006: fig. 10), it has moved to an external location posterior to the anterodorsal margin of the pereionite. ...
A new family-level taxon of deep-sea isopods, Basoniscus hikurangi gen. et sp. nov., was recovered from the Hikurangi Plateau in the deep sea off eastern New Zealand. The broad-bodied, eyeless, seemingly unremarkable isopod was unusual in its possession of features that characterize two different families: the shallow water Joeropsididae Nordenstam, 1933 and the deep-sea Haploniscidae Hansen, 1916. An analysis of superfamily Janiroidea G.O. Sars, 1897 was conducted to establish the affinities of the species. Multiple analyses were done using unweighted and implied weighted characters. Existing families were well supported, with B. hikurangi intermediate between Joeropsididae and Haploniscidae. The new species, however, cannot be placed in either family owing to its lack of important defining synapomorphies of each family. As a result, Basoniscidae fam. nov. was created to contain this new species. That rocky hard substrates are undersampled is another implication. Our understanding of deep-sea species richness will not be accurate until more efforts are made to survey these habitats, especially more sites in the southern hemisphere. These gaps in our knowledge of the deep sea impairs any general claims about the distribution of biodiversity on a global scale. This find demonstrates that museums hold underused but valuable resources for understanding and describing the biodiversity of the deep sea.
... Some detailed studies have been carried out at other localities on the MAR, notably in the Charlie-Gibbs Fracture Zone further north Dilman, 2013;Bell et al., 2016;Alt et al., 2019) and at various hydrothermal vents [Lucky Strike, Menez Gwen, Rainbow, Snake Pit, Logatchev and Trans-Atlantic Geotraverse (TAG)] (e.g. Bellan-Santini and Thurston, 1996;Sigvaldadottir and Desbruyères, 2003;Myers and Cunha, 2004;Cunha and Wilson, 2006;Larsen et al., 2006;Bellan-Santini, 2007;Corbera et al., 2008;Riou et al., 2010;Sarrazin et al., 2015;Bebianno et al., 2018;Klunder et al., 2020). In the PECA, macrobenthic communities have been reported to date only from the Broken Spur and Lost City hydrothermal vent fields (Tyler et al., 1995;Desbruyères et al., 2000;Kelley et al., 2005;Kelley et al., 2007;Goroslavskaya and Galkin, 2011;Rybakova and Galkin, 2015;Boschen-Rose and Colaco, 2021;Cruz et al., 2022) (see Table 3). ...
... Earlier studies from the MAR demonstrated that the rate at which new species are described, although increasing with time, is still very low (e.g. Tyler et al., 1995;Sigvaldadottir and Desbruyères, 2003;Myers and Cunha, 2004;Cunha and Wilson, 2006;Larsen et al., 2006;Bellan-Santini, 2007;Corbera et al., 2008;Budaeva, 2012). The identification of a wide range of different taxa in the PECA area, most of them new to science, is a particular challenge for a contractor. ...
In February 2018, the Government of Poland and the International Seabed Authority signed a 15-year contract for exploration of polymetallic sulfide deposits on a section of the Mid-Atlantic Ridge extending between the Hayes, Atlantic and Kane transform faults (32°45.378’ N, 39°57.760’ W to 26°14.411’ N, 44°18.008’ W). The contractor is obliged to collect data on the contract area environment and its ecosystem components. In this context, it is important that the contractor establishes a sound starting point which further baseline investigations can be referred to. Such a starting point involves assessment of currently held information and, most importantly, knowledge gaps on the ecosystem components in the area of exploration (and of potential future exploitation). Of major importance here is the knowledge on benthic communities, as it is the benthos that will be most affected by any human intervention in the area of interest. Based on available published evidence, we have reviewed the present state of knowledge on benthic communities in the Polish exploration contract area (PECA). In the process, we have identified important knowledge gaps that will need to be addressed during exploration surveys. These include, but are not limited to, the distribution and structure of benthic communities throughout the contract area, the spatial and temporal variability of those communities, possible differences between communities inhabiting active and inactive vent fields, connectivity issues and the recovery potential. Special consideration should be given to Lost City, a geologically and ecologically unique hydrothermal field which has been a focus of international research and an important conservation target.
... [8][9][10], on shallow coastal waters e.g. and works from deep seas exploration expeditions on the continental Canyons and Portuguese archipelagos of Azores, e.g. [11][12][13]. Macroinvertebrate surveys on the Minho River started on 1982 [14], but have been scarce with only a few works on macrobenthic ecology or specimens collected through glass eel fishing bycatch [15][16][17]. In this study we provide diagnostics features for the isopod fauna collected on the Minho River estuary, belonging to 13 species, 10 genera, five families and three suborders, with ecological notes, global and Portuguese distributions, and a key for species identification. ...
Isopods are a common, diverse, and abundant group of the littoral and estuarine invertebrate fauna. This study presents a survey on the species of isopods found on the Minho River estuary, Iberian Peninsula, using plankton net, glass eel fishing bycatch, grab sampler, and sein net sampling methods. A total of 248 specimens were analysed belonging to five families with 13 species in 10 genera. Brief diagnosis, ecological notes, species distributions, figures and a key to species identifications are provided aiming to provide taxonomic support on future projects on this area.
... The nomenclature adopted to description (morphological terminology) was based of Cunha & Wilson (2006) and Kavanagh et al. (2015), and nomenclature adopted to mouthparts was from Brökeland & Brandt (2004). For simple setae, long and short are used as relative qualifiers in respect of the appendage/structure being described (Araújo-Silva & Larsen 2012). ...
Three new species of genus Ischnomesus are described from three Brazilian sedimentary Basins: Alagoas-Sergipe, Espírito Santo and Campos. Ischnomesus hirsutus sp. nov. was found at depths between 1445 m and 3000 m in Alagoas-Sergipe Basin and Espírito Santo Basin. This species is characterized by having pereonite I with 1 pair of anterolateral small pedestal spines, pereonites I–IV with a pair of anterodorsal pedestal setae and pleotelson with lateral fields bulge Ischnomesus longiseta sp. nov. was found between 400 and 1000 m, on the upper slope in Alagoas-Sergipe Basin and Espírito Santo Basin, and is characterized by having the pereonites without spines or tubercles, but covered with long simple setae, pleotelson with 5 lateral simple setae, without spines or tubercles. Ischnomesus wilsoni sp. nov. was found on the upper slope between 750 and 830 m in Espírito Santo Basin and Campos Basin. This species has the body entirely ornamented with pedestal spines. This is the first record of the family Ischnomesidae for Brazilian waters.
... Lateral views of several deep· sea Asellota to show the range of morphological diversity; most taxa differ considerably from related families found in shallow water. (A) Chelator insignis (Hansen 1916), (B) Heteromesus ctenobasius (Cunha and Wilson 2006), (C) Xostylus sp., (D) Dendromunna compsa (Lincoln and Boxshall 1983), (E) Thylakogaster lobotourus (Wilson and Hessler 1974), (F) Macrostylis roaldi (Riehl and Kaiser 2012), (G) Vemathambema argentinensis (Malyutina et al. 2001), and (H) Eurycope cornuta (Sars 1864). Modified from original publications, except for A, from Hessler 1970 b; C, undescribed species from the Weddell Sea; E, from Cunha and Wilson 2003;and H, from Wilson and Hessler 1980. of the endemic deep-sea families have no relatives in shallow water and are likely to have evolved in situ (Hessler et al. 1979). ...
Deep-sea crustaceans that live below 200 meters (the approximate upper limit of this realm) have lifestyles that are different from their relatives in shallows waters. The crustacean groups range from the megafaunal decapods through the dominant macrofaunal peracarids to the tiny meiofaunal-sized ostracodes and harpacticoids. The smaller macrofauna and meiofauna are incredibly diverse, the discovery of which changed our ideas about global biodiversity. Like the latter two groups, their morphologies may differ little from those found at shallower depths, but some taxa are highly transformed by the different selective environment of the abyss. Eyes and pigmentation are absent and antennae and legs are typically longer, sometimes exceeding 3 or more body lengths. Deep-sea crustaceans also have more spines on their body, which might limit predation, but may also have other unknown uses such as changing their hydrodynamic profile. Among the peracarids, the isopods achieve the highest taxonomic and morphological diversity, often with strange shapes that we cannot begin to guess their functional adaptations. Although some deep-sea crustaceans show a comparative trend towards larger body size than in shallow water (deep-sea gigantism), because the smaller taxa become so abundant in the deep-sea, abyssal faunas have a smaller size on average than shallower faunas. Because the abyss is food-limited, nutrition primarily relies on carnivory or scavenging, and adaptations to avoid predation. Reproduction of the deep-sea crustaceans typically is accomplished through brooding and direct development or with some lecithotrophic larvae, although a few taxa retain epipelagic larvae. Because deep-sea taxa live at low population densities, successful reproduction may include highly motile males that are presumably adapted for finding females. Many regions of the deep-sea, being far from the surface atmosphere, also have low oxygen availability and may trend toward dysoxia in areas where the pelagic oxygen minimum zone intersects the sea floor. Crustaceans in such areas, however, have adapted to the extent that some taxa can thrive in vanishingly small amounts of dissolved oxygen. Similar adaptations are seen in non-crustaceans, suggesting that the environment of the abyss has a significant impact on all organisms that live there.
... The specimens collected by the N2 net of the 'Roscoff ' and the 'Arcachon' sleds probably reflect some contamination of samples by surficial sediments and have to be considered as resuspended organisms. These results suggest that the new species lives in close contact with surficial sediments, and support the assignment of an epifaunal/infaunal lifestyle to ischnomesid taxa (Hessler & Strömberg 1989;Thistle & Wilson 1996;Cunha & Wilson 2006). Few observations are actually available on the benthic behaviour of ischnomesid species. ...
A new species of Ischnomesidae (Crustacea: Isopoda: Asellota), Ischnomesus harrietae sp. nov. is described from the southern Bay of Biscay. This new species is distinctive due to the presence of numerous pedestal setae arranged in longitudinal rows on pereonite 5. Because of this morphological peculiarity, it can be easily distinguished from the four other Ischnomesus species previously reported from bathyal/abyssal bottoms of the European continental margin. Within its known distributional area, the new species inhabits sandy and muddy bottoms between 619 and 1099 m, with a maximum abundance of 41.8 individuals per 100 m<sup>2</sup> recorded at approximately 700 m on the Arcachon Plateau. Another new species is also reported, Ischnomesus sp.1, represented by one specimen only and briefly described. An identification key to European species of Ischnomesus is provided.
... In some asellote species, the terminal males show a pronounced sexual dimorphism. Usually such dimorphic males have some pereonites or appendages enlarged (see Just & Wilson, 2004;Cunha & Wilson, 2006;Doti & Wilson, 2010;Riehl et al. 2012). Within Paramunnidae, the most common changes in these final males are in the pereonite 1, whose lateral parts are enlarged, and in the pereopod I which become more robust (Just & Wilson, 2004). ...
Two new species of paramunnid isopods from Argentina are described: Munnogonium quequensis n. sp. from Buenos Aires Province (Quequén) and M. diplonychia n. sp. from Patagonia (Comodoro Rivadavia, Rada Tilly and Puerto Deseado). Both species are distinguished from their congeners by having a tight tuft of setae on the frontal margin. These setae have been discovered after examining the specimens under scanning electron microscope; under dissecting microscope they look like a short blunt median projection. M. diplonychia n. sp. differs from M. quequensis n. sp. by having bifid claws on pereopods II-IV. Eighty of the 92 specimens of M. quequensis n. sp. examined were found attached to the sea star Astropecten brasiliensis, a fact that suggests an association between these two species.
... Although so far discussed only for the Macrostylidae (discussion below) and the Paramunnidae (Just & Wilson 2004), a male that transforms substantially to the last instar occurs frequently among the Asellota. In the Ischnomesidae, the males can have substantially more elongate pereonites 4 and 5 (e.g., Heteromesus calcar Cunha & Wilson, 2006) and often have distinctly different spination patterns from the females (e.g., Cornuamesus longiramus (Kavanagh & Sorbe, 2006)). Some Desmosomatidae and Nannoniscidae show important transformations of the head (e.g., Pseudomesus pitombo Kaiser & Brix, 2007; Nannoniscoides latediffusus Siebenaller & Hessler, 1977). ...
In the Asellota, sexual dimorphism is often characterized by males that show pronounced morphological differences after the final moult compared to females but also to sub-adult males. Such a sexual dimorphism may strongly complicate allocation of these terminal males to conspecifics. Consequently, we regard it to be a likely explanation for why in 50% of the described species of the family Macrostylidae Hansen, 1916, only one sex is known. Based on detailed description of two previously unknown species of the isopod genus Macrostylis Sars, 1864, the changes in the morphology that can occur during the final
moult of the males are highlighted. M. dorsaetosa n. sp. is unlike any other species owing to the row of spine-like setae on the posterior margins of pereonites 5–6. M. strigosa Mezhov, 1999 shows remarkable similarity but lacks these setae. In M. papillata n. sp., cuticular ridges overlap posteriorly with the margin of the pereonites 1–4 and head forming a warty appearance. This species is easily identifiable and unlike any previously described macrostylid owing to the presence of the tergal articulation between pleonite 1 and pleotelson. Information for the identification of terminal males is provided and implications of our results for future taxonomic and systematic work on this isopod family are discussed.
... Type material: syntypes, ZMUC CRU-7130. This type material is now missing (Cunha and Wilson, 2006). Ischnosoma bispinosum G. O. Sars, 1866: 34;Meinert, 1890: 194;G. ...
Summary This catalogue comprises a complete record of the deep-sea isopods collected off the west coast of Ireland and Britain to date. Benthic samples were taken over a two-year period by the zoobenthos group of the National University of Ireland, Galway, aboard the RV Celtic Explorer. Additional material collected as part of an environmental assessment by an Irish environmental consultancy (Aqua-Fact), was donated by the Galway-Mayo Institute of Technology, Galway. Further samples collected by the U.K. Department of Transport and housed at the National Museums of Scotland, Edinburgh, were also examined. Records from peer-reviewed literature, published catalogues and reports are included in the list. Information is provided on the type specimens, type locality and depth range of the species, where known. Ten new records were reported for the area including one new species. An additional 15 new species were collected to be used in future research studies. It was noted that the species recorded in this area of the North East Atlantic bear an affinity to the fauna of the Northern Seas. A total of 40% of the species recorded in the study area are also found in the Northern Seas, supporting the hypothesis that the fauna of the Northern Seas consists of comparatively recent immigrants from the adjacent shelves. A comprehensive bibliography is provided and a history of deep-sea research in the area is presented.
... Among crustaceans, copepods and decapods are the most speciose (Heptner and Ivanenko 2002; Martin and Haney 2005). Among the peracarid crustaceans, the amphipods are the best represented (24 species; Bellan-Santini 2006), while tanaids and isopods are less frequently identified (Cunha 2006; Cunha and Wilson 2006; Larsen et al. 2006). Similarly, very little is known on the cumacean fauna of chemosynthetic-based marine ecosystems. ...
A new cumacean genus and species, Thalycrocuma sarradini gen. et sp. nov., belonging to the family Nannastacidae is described from several sites of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37°N, 1700 m depth). The new genus differs from others in the family by males lacking exopods on the pereopods 3 and 4 and having an antenna with a five-articulate peduncle and a short
flagellum. This is the first cumacean species that could be considered, at the moment, as endemic
from hydrothermal vent areas. Data on the ac companying fauna including other cumacean species
(Cyclaspis longicaudata, Bathycuma brevirostre, Procampylaspis sp. and Makrokylindrus sp.) and some ecological remarks are included. A key for the currently known genera of the family Nannastacidae is provided and the taxonomic position of some genera is discussed.
