Cirolanid Isopods Research Articles

Phylogenetic relationships of Sphaeromides Dollfus, 1897 (Crustacea: Isopoda: Cirolanidae) and some related taxa, with new considerations about Trogloaega Brian, 1923

ABSTRACT Molecular studies are often essential to infer phylogenetic relationships and biogeography in troglobiotic taxa, frequently characterised by convergent adaptations and cryptic species. Genetic analysis is a particularly useful tool in Dinaric karst, where palaeogeographic history complicates the interpretation of the evolutionary history of cave organisms. In this paper we estimate phylogenetic relationships in an entirely troglobiotic group of perceivable cirolanid isopods, inhabiting Dinarides and other Mediterranean regions, by a DNA-based approach, with a particular attention to the genus Sphaeromides. The originally more extensive genus Sphaeromides appears limited to S. raymondi in Southern France, while we suggest restoring the genus and name Trogloaega for the Dinaric taxa, previously attributed to Sphaeromides. The name and taxon Trogloaega have never been scientifically invalidated, just ignored. Results indicated that S. virei, formerly divided into three subspecies, consists of two or three distinct species, now named T. virei, T. mediodalmatina and T. montenigrina, the latter molecularly closer to T. mediodalmatina. The genus Trogloaega is genetically distant from Sphaeromides. Sphaeromides bureschi from Balkans (Bulgaria, Serbia) appeared closer to Trogloaega than to Sphaeromides. Our results contribute to the awareness that the isopod morphology is characterised by high level of homoplasy and molecular phylogenetic analyses are essential in identifying taxonomic units.

Life history and demographic evolution: Comparative population genetics in sandy beach crustaceans

Studies comparing the distribution of genetic diversity may help revealing connectivity patterns in marine populations, as they allow identifying factors behind genetic population structure and elucidating the relationship between the habitat and resident species. The macrofauna of sandy beaches constitutes an interesting study subject, since it includes species with contrasting life histories and dispersal strategies, with potential implications on connectivity. In this work, COI sequences of three peracaridan species with direct development (the talitrid amphipod Atlantorchestoidea brasiliensis and the cirolanid isopods Excirolana braziliensis and Excirolana armata), and one decapod with planktonic larvae (the hippid mole crab Emerita brasiliensis), were compared in order to evaluate the influence of dispersal and historical processes in the distribution of their genetic diversity in the Uruguayan coast, covering both marine and estuarine beaches located along the Rio de la Plata. The hypothesis that species with similar life histories show similar geographic patterns of genetic diversity did not completely explain the genetic variability observed in these species. The intertidal Emerita brasiliensis and the supralittoral Excirolana braziliensis presented high genetic homogeneity, with evidence of population expansion originated at similar times. This shared pattern of genetic variability could be explained by their tropical origin and recent colonization of the Uruguayan coast. The intertidal Excirolana armata and the supralittoral Atlantorchestoidea brasiliensis presented high variability, although differences between them could be associated with the beach zone they inhabit. The role of salinity affecting connectivity patterns was important in Excirolana armata and Atlantorchestoidea brasiliensis, which showed genetic differentiation between estuarine and oceanic beaches. Results reinforce the concept that the distribution of genetic variability not always reflects contemporary population structure and that it is important to consider the evolutionary history of the species when studying connectivity in sandy beach populations. Finally, the accelerated rates of warming in the region could favor a demographic explosion of Emerita brasiliensis and Excirolana braziliensis, species with tropical affinities, which is coherent with the documented demographic history of both species.

Ranking the ecological effects of coastal armoring on mobile macroinvertebrates across intertidal zones on sandy beaches

Coastal armoring is widely applied to coastal ecosystems, such as sandy beaches, in response to shoreline erosion and threats to infrastructure. Use of armoring is expected to increase due to coastal population growth and effects of climate change. An increased understanding of armoring effects on those ecosystems and the services they provide is needed for impact assessments and the design of these structures. We investigated the following hypotheses: 1) impacts of coastal armoring on beach macroinvertebrates increase from lower to upper intertidal zones and 2) location of an armoring structure on beach profiles affects the number of intertidal zones, using comparative surveys of armored and unarmored beach sections in Chile and California. The effects of armoring were greater for upper intertidal (talitrid amphipods) and mid-intertidal species (cirolanid isopods) than for lower shore fauna (hippid crabs). Our surveys of sections of armoring structures located higher and lower on the beach profile (with and without interactions with waves and tides), showed loss of upper zone talitrid amphipods and mid-zone isopods and a reduction of lower zone hippid crabs in sections where the structures were lower on the beach profile and interacted with waves, compared to non-interacting sections. Our results support the hypothesis that impacts of armoring on intertidal macroinvertebrates increase from the lower to the upper intertidal zones of sandy beaches and also suggest that the relative position of an armoring structure on the beach profile, determines the number of intertidal zones it affects. Our findings also imply that by altering the position of existing armoring structures on the shore profile and increasing the amount of interaction with waves and tides, sea level rise and regional factors, such as coseismic coastal subsidence, can be expected to exacerbate the impacts of these widely used coastal defense structures on sandy beach ecosystems.

A new species of Bathynomus A. Milne-Edwards, 1879 (Malacostraca: Peracarida: Isopoda: Cirolanidae) from the upper Miocene of the Guadalquivir Basin (Spain).

Today representatives of the giant cirolanid isopods of the genus Bathynomus inhabit tropical to warm-temperate waters of the West Atlantic and the Indo-West Pacific. In not so distant geological past, however, the genus was present also in the Mediterranean, as documented by numerous fossils from the Plio-Pleistocene of Italy. Herein, a somewhat older occurrence of the genus is reported, from the North-East Atlantic. Based on a single posterior moult from the upper Miocene (Tortonian) of southwestern Spain, a new species is described. Bathynomus civisi sp. nov. differs from its congeners by both uropod rami having the obtuse distolateral corner produced as a distinct tip and a wider gap between the second and third side distal spines than between others. The new species is so far known only from the type locality in close vicinity of Arroyo Trujillo, in the municipality of Cantillana (Seville, Spain), where the marls of the Écija Formation are exposed. At the time of deposition of these marls, the area represented a part of the Norbetic Strait, a corridor connecting the North-East Atlantic with the Mediterranean. The new occurrence reported herein further supports the environmental preferences of the genus throughout its geological past for deep-marine settings.

New distribution records of subterranean crustaceans from cenotes in Yucatan (Mexico).

New records of 14 stygobiont crustacean species pertaining to six Malacostraca orders from 32 cenotes are presented, with their associated caves of the state of Yucatan, Mexico, together with an individual account for each species. Species composition of most of the investigated cenotes is examined for the first time. A thermosbaenacean and two amphipod species were not formally recorded to the cenote ecosystems of the state of Yucatan prior to our research. Distribution data of a cirolanid isopod previously known only from its type locality is also provided. Barcodes of mitochondrial cytochrome c oxidase subunit I for the reported peracarid species previously lacking this information have been included in present study as tools for species identification and a baseline of further molecular genetic analyses.

The first fossil isopod from Argentina: a new species of Cirolanidae (Crustacea: Peracarida) from the Miocene of Patagonia

Cirolana centinelensis, a new species of fossil cirolanid isopod from the early Miocene of Argentina is described, and the fossil record of South American isopods is briefly reviewed. Few fossil isopods are known from South America, and none were previously known from Argentina. The new taxon is represented by a single specimen collected from the Estancia 25 de Mayo Formation, formerly known as the Centinela Formation, in the Calafate region of southern Patagonia. It is preserved in a concretion that was formed in a glass-rich volcanic ash deposited into a shallow epicontinental seaway. The high reactivity of the enclosing volcanic ash set the stage for unique and variable taphonomic conditions with some skeletal elements being preserved in high resolution, whereas others were completely obliterated by the formation of large crystals of secondary zeolites. Because mouthparts that are usually used to make familial and generic assignments are not preserved, traditional systematic methods are combined with a multivariate principal coordinate analysis, as well as ecological and paleontological considerations to evaluate the most likely affinity of the fossil isopod.

Macroscale patterns in body size of intertidal crustaceans provide insights on climate change effects.

Predicting responses of coastal ecosystems to altered sea surface temperatures (SST) associated with global climate change, requires knowledge of demographic responses of individual species. Body size is an excellent metric because it scales strongly with growth and fecundity for many ectotherms. These attributes can underpin demographic as well as community and ecosystem level processes, providing valuable insights for responses of vulnerable coastal ecosystems to changing climate. We investigated contemporary macroscale patterns in body size among widely distributed crustaceans that comprise the majority of intertidal abundance and biomass of sandy beach ecosystems of the eastern Pacific coasts of Chile and California, USA. We focused on ecologically important species representing different tidal zones, trophic guilds and developmental modes, including a high-shore macroalga-consuming talitrid amphipod (Orchestoidea tuberculata), two mid-shore scavenging cirolanid isopods (Excirolana braziliensis and E. hirsuticauda), and a low-shore suspension-feeding hippid crab (Emerita analoga) with an amphitropical distribution. Significant latitudinal patterns in body sizes were observed for all species in Chile (21° - 42°S), with similar but steeper patterns in Emerita analoga, in California (32°- 41°N). Sea surface temperature was a strong predictor of body size (-4% to -35% °C-1) in all species. Beach characteristics were subsidiary predictors of body size. Alterations in ocean temperatures of even a few degrees associated with global climate change are likely to affect body sizes of important intertidal ectotherms, with consequences for population demography, life history, community structure, trophic interactions, food-webs, and indirect effects such as ecosystem function. The consistency of results for body size and temperature across species with different life histories, feeding modes, ecological roles, and microhabitats inhabiting a single widespread coastal ecosystem, and for one species, across hemispheres in this space-for-time substitution, suggests predictions of ecosystem responses to thermal effects of climate change may potentially be generalised, with important implications for coastal conservation.

Typhlocirolana longimera sp. n. (Crustacea, Isopoda, Cirolanidae) from north-western Algerian ground waters with notes on Algerian Typhlocirolana

A new species of hypogean cirolanid isopod, Typhlocirolana longimera sp. n. is reported and described from a region located in north-western Algeria. Typhlocirolana longimera sp. n. can be distinguished from all other species of the genus especially by the peculiar shape of the merus of pereiopod I longer than in any other Typhlocirolana species, and for the presence of 6 molariform robust conical robust setae, the bottle shape of uropods and the aesthetasc formula of flagellum in antennulae. The presence in the same region of the two already known species T. fontis and T. gurneyi is also discussed.

A new species of Bathynomus Milne Edwards, 1879 (Isopoda: Cirolanidae)from The Bahamas, Western Atlantic.

A new species of cirolanid isopod, Bathynomus maxeyorum sp. nov., from The Bahamas, Western Atlantic, is described. This species represents the fourth species of Bathynomus to be described from the tropical and sub-tropical Western Atlantic. Bathynomus maxeyorum sp. nov. is characterized by 7 broad short pleotelsonic spines, with setation running along ~80% of the posterior margin of the pleotelson. Genetic analysis indicates a ~14% sequence divergence from the sympatric species Bathynomus giganteus.

New Fossil Record of the GenusBathynomus(Crustacea: Isopoda: Cirolanidae) from the Middle and Upper Miocene of Central Japan, with Description of a New Supergiant Species

Abstract. Three species of the cirolanid isopod genus Bathynomus are reported from the Miocene deposits of central Japan. Bathynomus kominatoensis sp. nov. and an unidentified Bathynomus sp. 1 are described from the upper Miocene Amatsu Formation in the Kominato-Osawa area, Chiba Prefecture. Another large species, Bathynomus sp. 2, was obtained from the middle Miocene Negishi Formation in the Iwadono Hills area, Saitama Prefecture. The new species most resembles Bathynomus giganteus, inhabiting the deep-sea floor of the Western Atlantic and Caribbean Sea. In addition to the large-sized body, Bathynomus kominatoensis sp. nov. and Bathynomus sp. 2 are included in the supergiant species group of the genus based upon morphology of the pleotelson and uropods. Both occurrences extend the geographic and stratigraphic ranges for the supergiant species group of Bathynomus into the Miocene of central Japan, although no species of the supergiant group is distributed in modern Japanese waters.

Variación nictemeral de los ensamblajes de macrocrustáceos en una playa arenosa del centro-norte de Veracruz, México

In this study, the structure of spatio-temporal variations of macrocrustacean assemblage were analyzed from the sandy beaches of Villa Rica, Veracruz. The nictemeral cycles related to lunar phases were taken into account; the non-metric multidimensional analysis showed an environmental stability trend. Within the macrocrustacean assemblages 9 species were recognized, of these, Emerita benedicti, Excirolana braziliensis, Excirolana sp. and Pseudohaustorius sp., were the dominant ones. The highest values of total density, species richness, and diversity were recorded during high tides. The cirolanid isopods and Emerita benedicti occurred in the lower unsaturated zone of the beach, and Pseudohaustorius sp. was found in the middle area. Macrocrustacean assemblage is simple, with low species richness (3-5) and low diversity values with significant differences throughout the study time; however, the assemblage structure complexity tended to be constant throughout time.

Mouthparts and their setae of the intertidal isopod Cirolana harfordi

The cirolanid isopod Cirolana harfordi is described as a scavenger and a predator that lives in the intertidal region. In order to understand the microanatomy of the mouthparts and the setae that allow this animal to handle and eat its food, a scanning electron microscopy study was conducted. C. harfordi displays a variety in the types of setae distributed on its mouthparts in a site-specific fashion, including complex setae placed on the medial edge of the maxilliped and maxilla. Terminal pores in some setae were found to contain a cupule, which is a hemispherical structure, housed in the concave recess of the pore, which demonstrates that the pore is more than merely a thinning of the cuticle as has been proposed. Future studies on setal morphology are needed for comparative microanatomy of cirolanid isopods.

An appraisal of the fossil record for the Cirolanidae (Malacostraca: Peracarida: Isopoda: Cymothoida), with a description of a new cirolanid isopod crustacean from the early Miocene of the Vienna Basin (Western Carpathians)

Abstract: Isopod crustaceans are rarely preserved in the fossil record. Herein, an appraisal of the fossil record for the cirolanid isopods is presented. Five genera are briefly discussed, including Bathynomus, Brunnaega, Palaega, Pseudopalaega and Cirolana. A key for the cirolanid genera known to date from the fossil record is provided based mostly on pleotelson characters. From the early Miocene of the Slovak part of the Vienna Basin, Cirolana feldmanni sp. nov. is described being only the fifth fossil Cirolana species known to date and one of the few with preserved appendages. The material exhibits preservation suggesting biphasic moulting; the mode of preservation suggests a rather short time between shedding the posterior and anterior parts of the exoskeleton instead of hours or even days known in extant taxa. As no subsequent transport or physical disturbance was inferred, the specimens can be stated as in situ preservation. From the palaeoecological point of view, it is concluded that Cirolana feldmanni sp. nov. is the first unequivocal fossil deep‐water Cirolana as suggested by the accompanied fauna.

The stygobiont Cirolanidae (Isopoda) of Israel and Sinai

ABSTRACT Three closely similar species of subterranean cirolanid isopods are distributed in Israel and Sinai. Turcolana steinitzi, from Galilee, lives in water in which the chlorinity is <50 mg/1. T. reichi, from the Negev and eastern Sinai, is known from habitats with a water chlorinity of 240–1500 mg/1. T. detecta n. sp. is described; it was found at two spring complexes unveiled by a recent marine regression on the western shore of the Dead Sea, having a water chlorinity of 3000–4000 mg/1. T. detecta n. sp. differs from the other two species especially by its distinctly more slender and elongated uropods, this being even more evident for the endopodites, which have a distinct shape and a remarkably variable armature of the internal margin.

First record of cirolanids (Crustacea, Isopoda, Cirolanidae) from the Middle Pliocene of Parma and Reggio Emilia Province (Emilia Romagna, N Italy)

We report two new forms of cirolanid isopods ascribed to &lt;em&gt;Palaega&lt;/em&gt; sp. and &lt;em&gt;P. steatopigia&lt;/em&gt; n. sp. (Cirolanidae) from the Middle Pliocene of Campore (Salsomaggiore Terme, Parma) and Monticelli di Quattro Castella (Reggio Emilia), Emilia Romagna, N Italy. This is the first record of &lt;em&gt;Palaega&lt;/em&gt; Woodward, 1870, reported from the Middle Pliocene of Emilia Romagna and in the paleo-Adriatic Gulf. &lt;em&gt;Palaega&lt;/em&gt; &lt;em&gt;steatopigia&lt;/em&gt; n. sp. represents the third species described in Italy and in the Mediterranean area

Chemosynthetic trophic support for the benthic community at an intertidal cold seep site at Mocha Island off central Chile

We analyzed C and N stable isotope ratios of benthic fauna and their potential food sources at an intertidal methane seep site and a control site without emanation at Mocha Island (central Chile). The objective was to trace the origin of the main food sources used by the local heterotrophic fauna, based on the hypothesis that chemosynthetic production could be partially fueling the local food web at the seep site. Food sources sampled at both sites included macroalgae, particulate organic matter and bacteria-like filaments found growing over the red algae Gelidium lingulatum within the areas of active methane release. At the control site, located 11 km away from the gas emanation, fauna exhibited moderate δ 13C values ranging from −16.2‰ (in a nereid polychaete) to −14.8‰ (in a cirolanid isopod), which were consistent with those of the potential photosynthetic food sources sampled at this site (−20.2 to −16.5‰). δ 13C values of the photosynthetic food sources at the seep site similarly ranged between −25.4 and −17.9‰. However, a portion of the animals at this site were consistently more 13C-depleted, with δ 13C values close to that of the seeping methane (−43.8‰) and the bacteria-like filaments (−39.2 ± 2.5‰) also collected at this site. Specific examples were the Marphysa sp. polychaetes (δ 13C = −44.7 ± 0.6‰), the Schistomeringos sp. dorvilleid polychaetes (δ 13C = −42.9‰), and the tanaid crustacean Zeuxo marmoratus (δ 13C = −37.3 ± 0.2‰). The significantly higher δ 13C values of the herbivorous gastropod Tegula atra at the seep site (−29.3 ± 3.1‰) than at the control site (−12.6 ± 0.3‰) also indicated differences among sites of the preferred carbon sources of this species. Mixing model estimates indicate that at the seep site bacteria-like filaments could be contributing up to ∼60% of the assimilated diet of selected invertebrates. Furthermore, several indicators of trophic structure, based in isotopic niche metrics, indicate a considerably higher variety of basal resources used at the seep site and a consequent enhanced trophic diversity, compared with the non-seep site. The isotopic data gathered at the seep site clearly and unequivocally reflects the ingestion of a 13C-depleted primary food source, which could be the bacteria-like filaments observed at this site.

Production of Excirolana armata (Dana, 1853) (Isopoda, Cirolanidae) on an exposed sandy beach in southeastern Brazil

The somatic and gonad productions of the cirolanid isopod Excirolana armata were analyzed by taking monthly samples from December 2003 to November 2005 on Una beach, Sao Paulo state (24°S), southeastern Brazil. Sampling was performed along three fixed transects established from the base of the foredunes to the waterline. Weight-specific growth rate was used to estimate the E. armata somatic production for 2004 and 2005, separately. The gonad production was estimated based on the monthly reproductive potential (mean number of eggs/embryos per female × monthly abundance of ovigerous females with near-release broods) for 2004. The annual somatic production of E. armata population varied from 15.57 to 17.25 g AFDW m−1 year−1 and the somatic production/biomass ratio (P s/B) from 3.55 to 3.14 year−1 for 2004 and 2005, respectively. The P s/B ratios were higher for males (4.02 and 3.19 year−1 for 2004 and 2005) than for females (3.10 year−1 for both years). The annual gonad production (P g = 1.07 g AFDW m−1 year−1) contributed about 15 and 6% to the total production (P s + P g) of females and the population, respectively. The proportion of gonad to somatic production of females (P g/P s) increased with individual size (ca 90% in the 7.5 mm size class), and the annual weight-specific gonad production (P g/B ratio) was estimated to 0.24 year−1. The high P s/B ratios estimated for E. armata derive from the fast growth of individuals and show the importance of this population to the energy flow on Una beach ecosystem. However, the low percentage of juveniles verified in this population and in other studies of populations of the genus Excirolana is discussed as an important source of underestimation of P s/B ratio.

Two new species of cirolanid isopods (Crustacea: Isopoda: Cirolanidae) from Qeshm and Kish Islands in the Persian Gulf

Two new species of cirolanid isopods, Baharilana kiabii sp. nov. from the western coasts of Qeshm Island and Cirolana tarahomii sp. nov. from the northern cost of Kish Island and the western coasts of Qeshm Island in the Persian Gulf are described. Baharilana kiabii sp. nov. is characterized by pleonite 5 with a median projection and a pleotelson with two longitudinal, parallel ridges and small tubercles on the dorsal surface. Cirolana tarahomii sp. nov. is distinguished by a lateral margins of the frontal lamina converging slightly towards the base, the distal margin is extended with a narrowly rounded apex; appendix masculina distally acute with bifid apex, pleotelson with a broadly rounded apex and 8 marginal robust setae, uropodal rami not deeply bifid.

Sensitivity of a cirolanid isopod to human pressure

Cirolanid isopods are conspicuous members of the supralittoral and intertidal fringes of sandy beaches around the world, being dominant in terms of number or biomass. Excirolana braziliensis is one of the most abundant species on exposed sandy beaches, both urbanized and preserved, of Rio de Janeiro in southeast Brazil. Considering the negative effects of urbanization and human pressure on sandy beaches, this study aimed to analyze the population structure and reproductive aspects of E. braziliensis in different stretches of Barra da Tijuca beach (Rio de Janeiro, Brazil), which differ with respect to urbanization and occupation by bathers. Monthly samplings of E. braziliensis were conducted throughout 12 months within urbanized and preserved stretches, including measurements of beach parameters and human pressure. The anthropogenic effect seems to be a relevant factor in explaining the variability in the population structure of this species. Negative significant correlations were found between the species density and the number of visitors, who massively occupies the urbanized stretches. Similar life history strategies were observed for different populations of E. braziliensis. Although high fecundity rates were reported to all stretches, the probability of eggs/embryos survival under the adverse conditions provided by the Barra da Tijuca beach is not clearly known. According to the results of this study, it could be inferred that the human pressure over Barra da Tijuca beach affects the populations: (1) directly, through human trampling and/or natural habitat jeopardizing; or (2) indirectly, by the isolation of individuals in the preserved stretch, located between environments subjected to intense disturbance. In such case, the species strategy to thrive in a protected area of restricted size, within a highly urbanized and occupied area by bathers does not appear to be the best conservation measure for peracarid species, as in E. braziliensis. Nevertheless, E. braziliensis turned out to be a good monitoring species of impacts due to its high resistance to environmental stress, persisting in highly urbanized areas dominated by bathers.

Molecular phylogenetic relationships among some stygobitic cirolanid species (Crustacea, Isopoda)

Within the Cirolanidae, a widespread family of marine isopods, about 23 genera are stygobitic and inhabit phreatic and anchialine ecosystems, with many endemic species. The Mediterranean area has a high biodiversity of subterranean cirolanids, which are considered thalassoid limnostygobionts. A molecular analysis was conducted using mtDNA genes to infer the phylogeny of species belonging to six of the seven stygobitic genera of Cirolanidae inhabiting the Mediterranean basin and to two American taxa: Faucheria faucheri, Marocolana delamarei, Saharolana seurati, Sphaeromides virei virei, Turcolana sp., 13 taxa of the genus Typhlocirolana and two American species, Antrolana lira and Speocirolana bolivari. The Typhlocirolana species are widespread in the western Mediterranean basin, with a concentration of taxa in the Maghreb region. Turcolana sp. is localised in the eastern Mediterranean, while F. faucheri and S. v. virei are north Mediterranean taxa. S. seurati, the taxon least morphologically adapted to subterranean life, belongs to a monospecific genus present in a Tunisian spring. The molecular phylogeny showed a high affinity among the American taxa and the Mediterranean Sphaeromides, clustering in the Sphaeromides group identified by previous morphological studies. Typhlocirolana species and M. delamarei constitute their sister clade within the Sphaeromides group. F. faucheri appears to be a sister clade of the Sphaeromides group. S. seurati, showing reduced troglobitic adaptations, assumes disparate and unsolved positions in the phylogenetic reconstructions. The molecular data suggest that a combination of vicariance and dispersal events, occurring from 180 to a few million years ago, combined to bring about the present distribution pattern of Mediterranean cirolanid isopods.