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Baeza, J.A. 2011. Squat lobsters as symbionts and in chemo-autotrophic environments. (Chapter 8). In: The Biology of Squat Lobsters (Poore G.C.B., Ahyong S.T., and Taylor J., eds). CSIRO Publishing: Melbourne and CRC Press: Boca Raton. Pp. 249-270.
Abstract
Some squat lobsters have adopted a symbiotic lifestyle and others colonised chemo-synthetic communities in the deep sea. Prior to 2010, 42 species of squat lob-sters were reported to engage in putative partnerships with a variety of macro-invertebrates but most com-monly with soft and black corals. Twenty-one species of Galatheoidea and 23 of Chirostyloidea are reported to establish some form of symbiotic association with other invertebrates. Thirty-three identified species of squat lobsters, most of them members of the Galathe-oidea, are reported from chemo-autotrophic commu-nities in the deep sea. Given the depth at which most squat lobsters occur, the paucity of information on many aspects of their lifestyle, life history, behaviour and ecology is not surprising.
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Lauriea siagiani new species from Bali, Indonesia is the second species of the genus. It is differentiated from Lauriea gardineri (Laurie, 1926) by lack of spines on both the distomesial margin of the antennular basal segment and the mesial margin of the second segment of the antennal peduncle, more slender distal segments of the antennule, more elongate eyestalks, less prominent anterior margin of the third thoracic sternite, and by different coloration.
The high level classification of the Chirostyloidea Ortmann, 1892, is reviewed. Eumunididae Milne-Edwards & Bouvier, 1900, is resurrected for two genera formerly placed in the Chirostylidae Ortmann, 1892, Eumunida Smith, 1883, and Pseudomunida Haig, 1979, based on shared characteristics such as the dorsal carapace striation, presence of supraocular spines of the rostrum, dentition of the mandible, presence of an epipod and an annulated exopod flagellum of maxilliped 1. Three families are now included in the Chirostyloidea: Chirostylidae, Eumunididae and Kiwaidae. Diagnoses are provided for each family as well as a key to the families. The fossil record of the Chirostyloidea is discussed, with putative records of Eumunida in the fossil record referred to the galatheid genus Sadayoshia Baba, 1969.
Four species of squat lobsters (Galathea amboinensis de Man, 1888, G. continua new species, G. inflata Potts, 1915, and G. leptocheir new species), all associates of comat-ulid crinoids, are described from material collected on coral reefs of the Ryukyu Islands. Galathea continua is found in association with Capillaster multiradiatus, Clarkcomanthus lit-toralis, Comatella maculata, C. nigra, C. stelligera, and Comanthus gisleni. It is distinguished from the other three species by the absence of a spine on the hepatic region lateral to the first transverse ridge of the carapace, the anterior margin of sternite 3 submedially produced into two spines instead of roughly bilobed, and epipods present on pereopod 1 only instead of pere-opods 1–3. Galathea leptocheir associated with Phanogenia gracilis is distinguished from G. amboinensis by much more slender pereopod 1, the carapace with four uninterrupted and three interrupted transverse ridges placed alternately instead of one interrupted and six uninterrupted ridges on the posterior half surface, and abdominal somites 2–4 with two uninterrupted instead of three uninterrupted transverse ridges. Coloration is also different in each of these species. A key to the four species is provided.
Nine species of Munidopsis Whiteaves, 1784, and one species of Galacantha A. Milne-Edwards, 1880 (Crustacea: Decapoda: Galatheidae) are reported from the continental shelf of Australia. Two species are new to science, M. comarge sp. nov. and M. vesper sp. nov. Munidopsis vesper is presently known only from Western Australia, but M. comargeranges from Western Australia to New Zealand. Six species are reported for the first time from Australian waters, G. subspinosa Macpherson, 2007, M. andamanica MacGilchrist, 1905, M. crenatirostris Baba, 1988, M. hirsutissima Balss, 1913, M. levis (Alcock & Anderson, 1894) and M. nitida (A. Milne-Edwards, 1880). A range extension within Australia is reported for M. dasypus Alcock, 1894 and M. kensleyi Ahyong & Poore, 2004. These new records expand the number of Munidopsis species previously recorded from Australian waters from 15 to 22 and the number of Galacantha species from three to four. A key and illustrated guide to the species now known from Australia is provided.
Knowledge of squat lobster diversity has grown rapidly during the past two decades and has now reached a level where it is possible to attempt a biogeographic synthesis. Squat lobsters of the superfamilies Galatheoidea and Chirostyloidea are now represented by more than 1000 species world-wide (10% undescribed) across nearly all latitudes and depths; the potential for new species discoveries remains high. Patterns of global species richness indicate a distinct global centre of diversity in the tropical western Pacific from between New Caledonia, Indonesia and the Philippines, with progressively fewer species recorded with increasing distance from this centre. This pattern holds for taxa in both superfamilies and across all depths, although a single unified centre of diversity is less obvious for lower slope and abyssal species (>2000 m) compared with their shallow-water relatives.
High-level classifications of Anomura typically recognize three major clades: Galatheoidea (squat lobsters and porcelain crabs), Paguroidea (hermit and king crabs), and Hippoidea (mole crabs). The general stability of this classification, however, has masked the vigorous debate over internal rela-tionships. Phylogenetic relationships of the Anomura are analyzed based on sequences from three molecular loci (mitochondrial 16S; nuclear 18S and 28S), with multiple exemplars representing 16 of 17 extant families. The dataset assembled is the largest analyzed to date for Anomura. Analy-ses under maximum parsimony and Bayesian inference recognize a basal position for Hippoidea, corroborating several recent studies, but point to significant polyphyly in the two largest super-families, Galatheoidea and Paguroidea. Three independent carcinization events are identified (in Lithodidae, Porcellanidae, and Lomisidae). The polyphyletic origin of asymmetrical hermit crabs is a radical departure from previous studies and suggests independent derivations of asymmetry in three separate clades: Paguridae, Coenobitidae + Diogenidae, and Parapaguridae. Such a scenario may seem unlikely owing to the complex characters involved, but if carcinization has multiple, independent origins, then adaptation to dextral shell habitation may also be plausible. Polyphyly of Galatheoidea, however, while unexpected, is morphologically tenable —characters traditionally used to unify Galatheoidea are plesiomorphies. Chirostylid squat lobsters are more closely related to an assemblage including aegloids, lomisoids and parapagurids than to other galatheoids. Galathei-dae may be paraphyletic on the basis of an internally nested Porcellanidae, and a similar situation may obtain for Chirostylidae with respect to Kiwaidae. Present topologies are not sufficiently robust to justify significant changes to the classification, but they point to fruitful lines for further research.
The carbon sources and trophic position of the abyssal species Munidopsis alvisca and Neolithodes diomedeae are described on the basis of stable carbon and nitrogen isotopes. These two species occur in large abundance at the hydrothermal vents in the central Gulf of California. As domi- nant components in the crustacean assemblage they define the use of resources and export of vent mate- rials to the abyssal ecosystem. The δ 13 C and δ 15 N values of the squat lobster Munidopsis alvisca sug- gest a mixed diet based on sediment surfur bacteria and metazoans associated with bacterial mats. The anomuran crab Neolithodes diomedeae is a scavenger feeding on infauna of the abyssal plain where photoautotrophic sources play the major role in the diet. The influence of the vents on the organic mat- ter composition of sediments is limited to the immediate venting area and is not recorded in sediments at distance from the active vent structures.
The Gulf of Mexico supports dense aggregations of megafauna associated with hydrocarbon seeps on the Louisiana Slope. The visually dominant megafauna at the seeps-mussels and tube worms -derive their nutrition from symbiotic relationships with sulfide or methane-oxidizing bacteria. The structure of the tube worm aggregations provide biogenic habitat for numerous species of heterotrophic animals. Carbon, nitrogen and sulfur stable isotope analyses of heterotrophic fauna collected with tube worm aggregations in the Green Canyon Lease area (GC 185) indicate that most of these species derive the bulk of their nutrition from chemoautolithotrophic sources. The isotope analyses also indicate that although 2 species may be deriving significant nutritional input from the bivalves, none of the species analyzed were feeding directly on the tube worms. Grazing gastropods and deposit-feeding sipunculids were used to estimate the isotopic value of the free-living chemoautolithotrophic bacteria associated with the tube worms (delta C-13 -32 to -20%o; delta N-15 0 to 7%; delta S-34 -14 to -1%). The use of tissue delta S-34 analyses in conjunction with tissue delta C-13 and delta N-15 led to several insights into the trophic biology of the communities that would not have been evident from tissue stable C and N analyses alone.
In this study the distributional pattern of the macro- and megafauna of a small (ca. 300 m(2)) Lophelia pertusa (L., 1758) reef was studied with a ROV (remotely operated vehicle). The reef is situated in a shallow fjord off the Swedish west coast. The number of taxa and their abundance in. transects from the reef itself and from 3 zones (Zone 1 = 50 m, Zone 2 = 100 m and Zone 3 = 200 M) around the reef were compared. Both the number of taxa (from 30 to 33 Tansect(-1)) and the abundance of individuals (from 21 to 7 m(-2)) decreased with increasing distance from the reef. Divided into ecological guilds, predators and filter-feeders decreased with distance from the reef (predators from 7 to 0.3 ind. m(-2), and filter-feeders from 13 to 6 ind. m(-2) from Zone 0 to Zone 3), while deposit-feeders increased with increasing distance from 0.04 to 0.4 ind. m(-2) from Zone 0 to Zone 3. Sessile species decreased more with increasing distance than mobile species, from 19 to 7 ind. m-2 and from 1 to 0.7 ind. m(-2), respectively. Our results also show that small deep-water coral reefs enhance local biodiversity, but the advantage to individual species depends on their mode of feeding and mobility.
Nutritional interactions among invertebrates at 3 vent sites on the Galapagos Rift are examined through the use of stable carbon and nitrogen isotopes. A large number of individuals of several vent species were analyzed and this provides previously unavailable insights into the variability within various groups. Stable nitrogen isotope contents (delta(15)N values) of vent invertebrates are below 11 parts per thousand. This is significantly lower than all non-vent deep-sea fauna examined to date, which makes delta(15)N values an excellent tool in identifying vent-dependent fauna. However, the large range in delta(15)N values among both primary producers and many Vent consumer species renders it of Limited use in determining either the trophic level of most individual species or the total number of trophic levels in vent communities. Stable carbon isotope content (delta(13)C values) in vent invertebrates from the Galapagos Rift range from -9 to -37 parts per thousand, which encompasses the range of non-vent deep-sea fauna (-17 to -22 parts per thousand) and extends significantly beyond it. Many vent invertebrates have delta(13)C values which overlap that of ambient deep-sea fauna, however in several cases the extreme values can be linked to specific endogenous vent sources. When both nitrogen and carbon are taken together, robust trophic links can be established between several vent taxa, and considerable nutritional plasticity in other taxa becomes evident.
Galathea amboinensis De Man, 1888 and G. inflata Potts, 1915, both known as associates of shallow water co- matulid crinoids, are reported for the first time from Japan. In the Ryukyu Is lands, Galathea inflata was found on 13 species of crinoids but most commonly on Comanthus parvicirrus (Miiller) and Comaster schlegelii (Carpenter). Gala thea amboinensis was recorded from 10 crinoid species but more often on Capil- laster multiradiatus (Linnaeus) than on other crinoids. Heterosexual pairs of G. inflata were found on 26.3 % of host crinoids (n=57), and all females were ovigerous. Megalopae of both galatheids were found on hosts, indicating that the larvae settled on crinoids at the megalopa stage.
Athanas anatidactylus sp. nov. is described on the basis of a holotype specimen collected in Nhatrang Bay, Vietnam, and an additional specimen from the Bohol Sea, the Philippines. The specimen from Nhatrang Bay was collected from a crinoid host. The new species is unique within the genus Athanas in having non-enlarged, symmetrical chelipeds ending in a peculiar claw with duckbill-shaped fingers, and the 3rd maxilliped having a broadened ultimate segment, distally armed with a row of strong spines. It is closely related to A. ornithorhynchus Banner and Banner, 1973, known as a facultative symbiont of filter-feeding brittle stars. An earlier report of a crinoid-associated Athanas (Bruce 1987) suggests that A. anatidactylus sp. nov. may also occur on the Great Barrier Reef, Australia. http://zoolstud.sinica.edu.tw/Journals/46.2/162.pdf.
A new chirostylid crustacean, Chirostylus stellaris, is described from the Ryukyu Islands, southwestern Japan. The new species is morphologically close to C. ortmanni Miyake & Baba, 1968, but distinguishable by the armature of the meri of the male first pereopods and the proportion of lengths relative to the heights of the propodi of the second to fourth pereo- pods. The live coloration of the pereopods is also clearly different in the two species. Chirostylus ortmanni is described on the basis of specimens from various localities in Japan, to complement the original account of the species.
To explore the crustacean fauna associated with deep-water gorgonian corals, suction samples were taken from colonies of Paragorgia arborea and Primnoa resedaeformis using a Remotely Operated Vehicle. Seven colonies of P. arborea and eight of P. resedaeformis were sampled from 330–500 m depth in the Northeast Channel off Nova Scotia. A total of 17 species were identified as being associated with the corals. The P. arborea fauna was richer than the P. resedaeformis fauna in both abundance and number of species, with 1303 versus 102 individuals and 16 versus seven species, respectively. However, 13 of the species associated with P. arborea were from hydroids attached to the coral. Amphipods dominated the fauna both in abundance and numbers of species and the most common species were Metopa bruzelii, Stenopleustes malmgreni, Proboloides calcarata and Aeginella spinosa. The isopod Munna boecki and the cirripede Ornatoscalpellum stroemii were also quite common. The most strongly associated crustaceans were two parasitic poecilostomatid copepods; these are common also on tropical gorgonians and are most likely obligate associates. The frequently occurring shrimp Pandalus propinquus probably avoids predation by seeking protection among the coral branches. Shrimp counts from video records showed that visual inspection without physically disturbing colonies will generally not reveal the crustaceans hidden in coral colonies. The galatheid Eumunida picta was observed on P. resedaeformis colonies. The fauna of the deep-water gorgonians corresponded to the fauna of tropical shallow-water gorgonians in the numerical dominance of amphipods and parasitic copepods; however, species richness is higher and decapods, which constitute a rich fauna on tropical gorgonians, were only represented by two species.
This chapter overviews embryonic and larval development of squat lobsters, as well as egg size, fecundity, larval dispersal and recruitment. Coverage of embry-onic development is focused on Galathea and Munida, leaving extensive studies to be done on early cleavage and on other genera, especially those having large eggs. As in other decapod crustaceans, the larval development of squat lobsters is referable to either the 'regular' type or the 'abbreviated' type, reflected by egg size. Morphological characteristics of larvae and their changes during larval development are summa-rised for each genus. Additionally, a key to the first zoeae of squat lobster genera is provided. Larval dispersal and recruitment pattern of Munida gregaria, Pleuroncodes planipes and P. monodon are briefly mentioned in the context of early life history.
Reproductive areas, larval and postlarval drift, and population structure of the red crab Pleuroncodes planipes (Stimpson) are described using samples obtained off the southwest coast of Baja California in May, June, August, and November 1986, July 1988, and September 1993. The highest abundance of larval and postlarval stages were found in May. Based on the ages of the most abundant postlarval stages, the most intense reproductive period was probably in January and February. The larval production recorded June to November indicated sporadic reproduction. We confirmed that the nearshore regions located near Bahia Magdalena 24° N and Punta Eugenia 28° N are the primary nursery areas. Seasonal hatching areas were in the vicinity of upwelling regions. Major production of larval stages starts in the south. At the end of the reproduction season, the highest abundance is in the north suggesting this species has a seasonal reproduction cline keyed to the normal upwelling cycle along the west coast of Baja California. From the hatching areas, a larval drift caused by offshore surface transport, in turn caused by the upwelling, was seen. A one-celled cross-shelf circulation is proposed to explain the offshore larval drift at the west coast of Baja California. This process could play an important role in the recruitment of postlarval stages to the adult epipelagic population. Two size groups of adults were found in the water column. Both groups were found simultaneously only inshore and during the seasonal reproductive months (spring). The group of largest size found inshore are individuals of the benthic phase that may have migrated into the pelagic zone for reproduction. Using data of this study and the current available information, a conceptual model of the life history of P. planipes along the west coast of Baja California is proposed.
A collection of Crustacea Galatheidea made by the Japanese Fisheries Research Vessel “Kaiyo Maru” off the east coast of the South Island, New Zealand, contains four new species described here: Gastroptychus novaezelandiae sp. nov., Uroptychus tomentosus sp. nov., Munida chathamensis sp. nov., and Munidopsis kaiyoae sp. nov.
Prior to the present study, seven species of deep-sea Chirostylidae (‘squat lobsters’), were known from New Zealand: Gastroptychus novaezelandiae, Uroptychodes spinimarginatus, Uroptychus australis, Uroptychus maori, Uroptychus novaezelandiae, Uroptychus politus, and Uroptychus tomentosus. All species are examined from type material and discussed, original illustrations supplemented, and new records provided where available. Uroptychus maori and Uroptychus novaezelandiae are re-described. The chirostylid fauna of the Kermadec Islands, a remote group of islands north-east of New Zealand, is studied. Uroptychus alcocki and Uroptychus scambus are reported for the first time from New Zealand, and six new species of the genus Uroptychus are described. Distributional patterns of New Zealand species are discussed and a key to New Zealand Uroptychus species is presented.
Three new species of galatheid crabs, Munidopsis ryukyuensis n. sp. and Munidopsis longispinosa n. sp., both associated with hydrothermal vents in the Hatoma Knoll, East China Sea, and Munidopsis naginata n. sp. associated with hydrothermal vents in the Hatoma Knoll and cold seep in Sagami Bay are described and illustrated. Their affinities to closely related species are discussed. The records of Munidopsis species associated with hydrothermal vents in the West Pacific Ocean are increased to seven. The habitat of the new species is briefly described. Distributional patterns of vent associated Munidopsis in the West Pacific is briefly discussed.
Munidopsis myojinensis n. sp., herein described and illustrated from Myojin Knoll and Northwest Eifuku Seamount in the Western Pacific, is the tenth species of Munidopsis known to be associated with active hydrothermal vents. It resembles M. starmer Baba & de Saint Laurent, 1992 in general ornamentation and spination of the body but differs in the erectness of the eyespine and form of the telson plates. Information on genetic identification using mitochondrial sequences (COI) is provided. Distributions of the vent associated Munidopsis in the Western Pacific and the habitat of the new species are briefly described.
Lauriea siagiani Baba, 1994 is recorded for the first time from Japanese waters based on a specimen collected from Hachijo-jima Island, the Izu Islands, Japan. This is the second reliable record of the galatheid, and extends its geographical distribution northwards to the latitude of 33° N. In addition to the characters discussed in the original description, this species can be distinguished from L. gardineri (Laurie, 1926) by the presence of long plumose setae on the carapace.
A new species of chirostylid decapod crustacean, Gastroptychus salvadori, is described from a specimen collected in association with a brisingid starfish by submersible off the Bahamas. A number of other chirostylids and galatheids, collected together with their echinoderm associates in the tropical and sub-tropical western Atlantic, are also reported. Some of these associations were previously unsuspected. The collections suggest that at least some of the decapods live together as mated pairs on their hosts. Traditional benthic sampling gears such as trawls and dredges disrupt any but the most robust associations between different animal species. Nevertheless, there are nu-merous reports in the literature of behav-ioural associations between decapod crus-taceans and other benthic organisms, particularly coelenterates, sponges and echi-noderms. Moreover, evidence for such as-sociations has been found even in the fossil record (Bishop & Portell 1989). Most of these records are from relatively shallow regions, but the use of manned submersibles permits observations of such associations to be extended to deeper waters, and par-ticularly to areas where the use of more con-ventional sampling techniques is precluded. Observations, photographs and collections made from the Johnson-Sea-Link (JSL) submersibles (Harbor Branch Oceano-graphic Institution, Inc.) in the tropical and sub-tropical western Atlantic during recent years have already provided data on asso-ciations between pontoniine shrimps and deep sea echinoids (Bruce 1986a, 1986b; Berggren & Svane 1989). This paper reports a small collection of galatheoid crustaceans secured along with their associates during these and other dives off the Caribbean is-lands of Barbados and St. Vincent. Material described herein has been deposited at the National Museum of Natural History, Smithsonian Institution (USNM) and the Harbor Branch Oceanographic Museum (HBOM).
The deep-water squat lobsters, Chirostylidae, of southern Australia are reported, comprising 31
species in three genera, increasing the known Australian fauna from 8 to 34. Two species of Eumunida
Smith are reported, one of which, E. capillata de Saint Laurent & Macpherson, is a new record
for Australia. Four species of Gastroptychus Caullery are reported, of which G. spinirostris is
described as new, and G. hendersoni Alcock and G. sternoornatus Van Dam are new Australian
records. A key to the Indo-West Pacific species of Gastroptychus is given. The known Australian
fauna of Uroptychus Henderson is markedly increased from 4 to 26. Twenty-five species of Uroptychus
are reported from the southern Australia. Twenty species of Uroptychus are described as new
and two are reported for the first time from Australian waters. A key to the 26 known Australian
species of Uroptychus is given. Uroptychus latirostris Yokoya from Japan, is removed from synonymy
of U. cavirostris Alcock, from the Andaman Sea. The results of the present study indicate that
the southern Australian chirostylid fauna is considerably more diverse than indicated by previous
studies.
Stable isotope ratios (180/160 and I3C/12C) in calcium carbonate exoskeletons of shrimp Alvinocaris lusca and galatheid squat lobsters Munidopsis subsquamosa from hydrothermal vents may provide a record of post-molt water temperature and chemistry experienced by each individual. Shrimp and galatheids appear to occupy distinct environmental regimes which are well-defined in terms of 6'80 and 613C values, and which correspond to specific regions of vent habitats. Each species may occupy these areas in a complex manner, dependent on size, sex, and reproductive state. Several mechanisms that might maintain these differences in distribution are proposed.
Crabs of the family Lithodidae are frequently encountered in the vicinity of deep-sea hydrothermal vents and cold-seeps. Together with crabs of the families Galatheidae and Chirostylidae, they are the main contributors to the scavenging/predatory fauna of these highly productive areas, and a potential vector for the export of organic carbon to the surrounding deep-sea commu nities. A review of the literature indicates that anomuran crabs have been re ported from such environments since their discovery, and occur virtually any where a reducing habitat is found. These three families are represented by at least eight genera, with at least 14 species occurring in hot vent areas, and eight in cold-seep associated communities.
Correlated the size, shape, color and behaviour of Latreutes fucorum and Hippolyte coerulescens with the architecture and color of the Sargassum natans habitat (number, size, shape and arrangement of structural components of the habitat). Latreutes most resembled Sargassum fronds, while Hippolyte resembled the gas-filled bladders (vesicles). As shrimps outgrow the specific plant parts they mimic, they use color patterns to camouflage themselves and generally resemble the Sargassum habitat matrix. -from Author
Munidopsis sarissa, a new galatheid crustacean associated with gorgonian corals, is described from Taiwan at depths of about 1000 m. This new species is unique in the genus by having an extremely spinose carapace with elongated spearhead-like rostrum, fourth thoracic sternite much larger than following sternites, and very long and slender chelipeds possessing broad coxae which are clearly visible from the dorsal view of the animal.
Protandric hermaphroditism in a mole crab, Emerita asiatica, is described. Neotenous males occur at 3.5 mm carapace length (CL) and above, whereas females acquire sexual maturity at 19 mm CL. The neotenous males, as they continue to grow, gradually lose male functions and reverse sex around 19 mm CL. The dis appearance of genital papillae is the first visible sign of sex reversal; spermatogonial activity in testes ceases but hyperactivity of the mesodermic cells ensues. In the CL range of 19â€"22 mm, the male's gonad comprises inactive testicular and active ovarian portions; the median ovarian limb beyond the fused posterior extremity of the testes lacks testicular elements; and the vas deferens is intact but a pair of functional oviducts is formed. These intersexuals possess three pairs of pleopods. A few have eggs, and thus constitute secondary females in the population. Andro genic glands, active in the neotenous males, show signs of degeneration in the larger males, and disappear in the intersexuals. The mesodermic cells of the gonad undergo important functional changes during sex reversal. Sex-changers with incomplete transformation of testis into ovary and imperfectly differentiated oviducts are also reported.
A new galatheid, Munidopsis lentigo, is described from depths of 2600 m on a thermally active area of the East Pacific Rise. The species has distinctive organs on the chelae and strikingly flattened eyes. Similarities to other species in the genus are discussed. Exploration of thermally heated vent areas on rift zones of the East Pacific Rise has yielded yet another previously unknown decapod crustacean species which is here described. One of us (CLVD) participated in the OASIS Expedition to vent sites at 2PN aboard the R/V Melville, 12 April to 8 May 1982, during which collections of Munidopsis and other decapods were made by various in vestigators with the aid of the deep submersible ALVJN on Dives 1211 and 1221. Munidopsis lentigo, new species
Adults of the reddish green symbiotic crab Allopetrolisthes spinifrons obtain different degrees of camouflage from the red, green, reddish green, and blue sea anemones Phymactis clematis, and the orange Phymanthea pluvia on which they are commonly found. Previous studies have indicated that the distribution of the crab on sea anemones may be influenced by the host's coloration. During the present study, we tested whether adult crabs dwell more commonly on those sea anemones that offer a higher degree of camouflage, and whether ''behavioral preferences'' can explain crab distribution on sea anemone species and color morphs in the field. We examined the frequency of occurrence of adult crabs on 200 sea anemones of each color morph, and crab distribution was compared to that expected by the relative abundance of different anemone hosts in the field. Adult crabs occurred more frequently than expected by chance on sea anemones most similar to their own color (reddish green), and occurred less frequently than expected by chance on sea anemones where homochromy was reduced (e.g. blue). Multiple host selection experiments conducted under laboratory conditions demonstrated that adult crabs avoid blue sea anemones compared to other host color morphs offered for colonization, but no preference was observed among red, green, reddish green, and orange sea anemones. These results suggest that ''behavioral preference'' play a role in determining the field distribution of A. spinifrons adult crabs in the field. The lack of preference for reddish green sea anemones in the laboratory, but its high frequency of occupancy by adult crabs in the intertidal, further suggests that factors other than homochromy-related preferences (e.g. sea anemones habitat) might affect crab distribution in the field. Alternative host selection experiments revealed that the specific host from which crabs were 0022-0981/02/$ -see front matter D 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 -0 9 8 1 (0 2) 0 0 4 7 6 -8
A deep-sea hydrothermal organism is reported for the first time from the coast of Taiwan. The species, Shinkaia crosnieri Baba and Williams, 1998, is a galatheid crab of the recently described subfamily Shinkaiinae Baba and Williams, 1998, previously known only from the Bismarck Archipelago and Mid-Okinawa Trough in Japan. Two specimens of this species were collected off northeastern Taiwan at a depth of about 1200 m from the southern end of the Okinawa Trough. S. crosnieri has been reported to form dense aggregations in hydrothermally active areas and one of the Taiwanese specimens has the largest size known for this species.
The galatheoid, Eumunida picta, primarily has been reported from deep sea corals and methane seeps; we examined its association with the deep-sea coral, Lophelia pertusa in a non-seep habitat. We used a remotely operated vehicle (ROV) to quantify invertebrate epifauna on six shipwrecks in the Gulf of Mexico in depths of 150 to 1950 m during summer, 2004. Video transects were conducted from over the shipwrecks to 333 m away from the wrecks. Eumunida picta specimens were observed on one of the six wrecks, from 530 to 560 m depth. When present, E. picta were primarily in association with Lophelia pertusa. Eumunida picta were associated with L. pertusa in >80% of the observations and were usually within 1 m of the coral when not in direct contact. The coral may be providing an optimal feeding location for the galatheoid, refuge from predation, or some combination of those.
French
Le Galatheoidea Eumunida picta a été tout d'abord découvert dans les coraux profonds et les suintements de méthane; nous avons examiné son association avec le corail profond, Lophelia pertusa dans un habitat non suintant. Nous avons utilisé un système téléopéré à grande profondeur (ROV, Remotely Operated Vehicle) pour quantifier l'épifaune invertébrée sur six épaves de bateaux dans le golfe du Mexique à des profondeurs de 150 à 1950 m au cours de l'été 2004. Des transects vidéos ont été réalisés depuis les épaves jusqu'à 333 m autour de celles-ci. Des spécimens d'Eumunida picta ont été observés sur l'une des six épaves, à une profondeur de 530 à 560 m. Quand ils étaient présents, les spécimens de E. picta étaient associés au Lophelia pertusa. Les Eumunida picta étaient associés à L. pertusa dans plus de 80% des observations et étaient habituellement présents dans une zone de 1 m autour des coraux quand ils n'étaient pas en contact direct. Les coraux pourraient procurer à ce Galatheoidea un excellent site pour se nourrir, un refuge face à la prédation ou une combinaison des deux.
A hitherto undescribed association between the comatulid, Antedon mediterranea and the galatheid crab, Munida intermedia, from the Tyrrhenian Sea (Mediterranean Sea), is herein reported.Three pairs of Antedon/Munida were sampled on muddy bottoms at a depth ranging from 10 to 95 m. The crabs collected were too small to establish their sex, and two of them were smaller than previously recorded. The specimens of M. intermedia were found on the external side of the arm base of the host and showed a cryptic coloration pattern. The relationship between A. mediterranea and young M. intermedia is not yet clear. The first seems to be a passive partner, while the latter probably takes advantage of its position on the crinoid's arm. The crab may find protection and shelter, and it may capture planktonic matter or larger living prey.
Italian
In questa nota si riporta la segnalazione della associazione, ad oggi mai descritta, tra il comatulide Antedon mediterranea e il granchio galateide Munida intermedia, nel Mar Tirreno (Mar Mediterraneo). Sono state collezionate tre coppie di Antedon/Munida provenienti da fondi mobili tra 10 e 95 metri di profondità. I granchi sono risultati troppo piccoli per poterne determinare il sesso e due di essi sono risultati i più piccoli mai registrati per questa specie. Gli esemplari di M. intermedia sono stati rinvenuti alla base del braccio dell'ospite, sulla parte esterna e presentavano un pattern di colorazione simile al crinoide. Le relazioni che possono intercorrere tra A. mediterranea e giovani di M. intermedia non sono ancora chiare.Quest'ultimo probabilmente trae vantaggio dalla sua posizione sul braccio del crinoide, che invece sembrerebbe un partner passivo. Il granchio può trovare protezione e riparo e può catturare materiale organico sospeso o prede vive di maggiori dimensioni.
In 1991, after 3 years of fishery prohibition, the most important surviving population of squat lobster (Pleuroncodes monodon, Galatheidae, Decapoda) on the continental shelf of central Chile, the Achira population (36 °S, 73 °W), reached the highest biomass recorded since the start of population assessments in 1979 (34 084–43 910 t, 95% confidence interval), and expanded its distribution by 56 km to the north. The age composition of the population was characterised by two strong year-classes (1988 and 1989, born at the end of the previous fishing period and at the start of the prohibition respectively) and a mixture of older year-classes, less important in terms of numerical abundance. Population expansion had a clear spatial structure. The 1989 year class (mean size 23.5 mm carapace length) populated the traditional southern population area, while the 1988 and older year-classes (mean carapace length 33.5 mm and 39.5 mm, respectively) populated the areas to the north which were vacant prior to the fishery closure in 1989. We interpret this spatial structure as the result of size-dependent dispersal capacity, with recruitment of the 1989 year-class providing the impetus for expansion of the individuals of the 1988 and older year-classes. Using the simple age structure of the Achira population, we estimated an average rate of population increase of 10 323 t year−1 during the period without harvesting, and a rate of expansion of 20 km year−1. Most of the reproductive potential (eggs km−2) was transported into the expansion zone, which may create new nursery grounds towards the north. This in turn may alter the spatial distribution of size, if recruitment is successful in the northern areas, with a potential effect on expansion dynamics.
Specimens of the genus Eumunida have been studied from various localities in the Atlantic Ocean. Comparisons of specimens from northwest and southwest Africa with material of E. picta from the western Atlantic Ocean has revealed two new species: E. bella nov. and E. squamifera sp. nov.
E. squamifera from the coast of Namibia, South West Africa, is distinguished from the two other atlantic species by a scaley striation of the carapace.
The northwest African E. bella and the western Atlantic E. picta, type of the genus, are closely related species, but differ from each other by the number and size of carapace marginal spines, shape of the anterior margin of the third thoracic sternum, and the ridges on the second abdominal segment. Their coloration is also different.
One specimen from the Tasman Sea identified by Gordon in 1930 as E. picta represents a further new taxon, E. australis sp. nov. It is readily distinguished from the three Atlantic species by the number of carapace anterio-lateral spines and the long acute projections of the third thoracic sternum.
All these species belong to the group A, as defined by Gordon (1930).
Preliminary studies have shown that males and females of the freshwater crayfish Parastacus brasiliensis (von Martens, 1869) have an intersexed internal genitalia characterized by the existence of genital ducts of both sexes that connect to a gonad with male or female components, according to the sex. To determine the type of sexuality of this species, specimens (n = 92) from 11.7 to 40.0 mm carapace length were collected at Mariana Pimentel municipality, Rio Grande do Sul, Brazil (30°20′39″S, 51°22′39″W). Anatomical and histological analysis of the gonads disclosed the existence of three sexual forms: (1) intersexed males (n = 36), (2) transitionals between male and female sex (n = 8), and (3) intersexed females (n = 48). The transitionals present the following common morphological features: both genital apertures are present, but the female apertures are closed, as is usual in males; coexistence of oocytes and testicular acini in the same gonad (ootestis); and a longitudinal collecting tubule, large in diameter in the testicular region. The ovarian component of the gonad includes previtellogenic and primary vitellogenic oocytes. Of the 44 individuals classified as males by the analysis of the aspect of the genital apertures, 18.2% were transitionals, suggesting the existence of primary males that never change sex and a sexual system that is known as partial protandry. The existence of small females suggests that some females never go through a male phase. The histology of the gonads and genital ducts is described, and the germ cells are identified in each sex. The possible reasons for the existence of hermaphroditism in the studied population are discussed based on theoretical models.
A species of squat lobster, Munidopsis kermadec new to science is described and illustrated from a hydrothermal vent area in Brothers Seamount, Kermadec Volcanic Arc, Southwest Pacific Ocean. It is distinguished from the allied Munidopsis lauensis, by the shape of rostrum, the erectness of eye spines, structure of the sixth abdominal segment and dactyl morphology of P2-4. This new record increases the number of species of Munidopsis reported from Southwest Pacific vent fields to five. A key is provided to distinguish the vent associated Munidopsis. New records of M. lauensis and M. sonne from Brothers Seamount are also reported here and this extends their distribution further south to the western Pacific. The habitat of the new species is briefly described. A note on the Munidopsis diversity in West Pacific vent fields is also provided.
The porcellanid crab Liopetrolisthes
mitra is a common associate of the black sea urchin, Tetrapygus
niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L.
mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L.
mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L.
mitra and T.
niger is strong and persists throughout the benthic life of the commensal crab.
Two new species of Munidopsis from the hydrothermal vent area, Kairei Field, Central Indian Ridge in the Indian Ocean and Forecast Vent Field, Mariana Back Arc Basin in the west Pacific are described and illustrated. Their affinities to closely related species are discussed. The number of Munidopsis species associated to hydrothermal vents in the world oceans has increased to 16. The habitat of new species is briefly described and the pattern of abundance of vent associated Munidopsis is briefly discussed.