Comparing genetic markers efficiencies for discrimination between two commercially important holothuroids in the Mediterranean Sea, Holothuria polii and Holothuria sanctori.

Sea cucumber (bche-de-mer, Echinodermata: Holothuroidea) is one of the top internationally traded seafood varieties. Besides its direct nutritional benefits, it is continuously used in the traditional medicine in different areas and cultures in the world. This world-wide interest triggered various issues related to stocks declining and risks of species extinction. For these reasons, the current study was designed to provide molecular tools for accurate discrimination between two sea cucumber species that prevail the Mediterranean of these echinoderms in Egypt, that are Holothuria polii and H. sanctori. The power of three gene markers, i.e., 16S rDNA, 28S rDNA, and Histone H3 in achieving accurate DNA-based identification, as well as elucidating clear phylogenetic and genetic diversity differences between those two species was assessed. Among the three genes, 16S rDNA showed the highest potentials as genetic and phylogenetic species discrimination marker. Both 28S rDNA and H3 exhibited the least number of holothuroid reference sequences in the GenBank database. For genetic diversity within each species population, 16S rDNA exhibited the best potentials, followed by H3. 28S rDNA showed no genetic polymorphism at all. Moreover, the collective data of both H3 and 16S rDNA suggested a possible role of asexual reproduction behavior in H. sanctori in the reduction of genetic diversity, as a possible response to overfishing. Hence, the current research can recommend the simultaneous application of both 16S rDNA and H3 as accurate markers for genetic discrimination among H. polii, H. sanctori and other different holothuroid species.

A new species of Parathyone (Holothuroidea: Dendrochirotida: Cucumariidae) from northeastern Brazil, with a key to species.

A new species of Dendrochirotida sea cucumber, Parathyone itapuaensis, is described and illustrated herein based on specimens collected from rocky intertidal regions of the northeastern coast of Brazil. The new species is characterized by a suite of morphological characters revealed by light stereomicroscope, SEM and microCT studies of the calcareous ring, dermal ossicles, Polian vesicles and madreporite. Parathyone itapuaensis sp. nov. is characterized by having 10 tentacles, two Polian vesicles and single madreporite; length of anterior process (radial plate) larger than length of the base of the radial plate; body wall with buttons with triangular knobs and knobbed multiperforated plates in the anal region; and tentacles with arched rods, knobbed in the margins and shallow cups knobbed in the outer and inner surfaces. A key to the recognition of Parathyone species is given.

Metabolomic analysis of white, green and purple morphs of sea cucumber Apostichopus japonicus during body color pigmentation process.

The sea cucumber Apostichopus japonicus is an important economic species owing to their high nutritive and medicinal value. Body color is one of the most important traits in the cultivation, which affects taste and market price of holothurian products. Pigmentation is an important stage of sea cucumber growth and development, in addition to achieving rare and beautiful coloration. In this study, UHPLC-QTOF/MS technique was performed to analyze the metabolome of white, green and purple A. japonicus body wall during the pigmentation process. A total of 2633 metabolites were identified. OPLS-DA clearly discriminated the body wall metabolites among the three color morphs. In addition, 13 annotated metabolites that could discriminate white, green and purple A. japonicus were screened out. KEGG metabolic pathway analysis revealed that "biosynthesis of unsaturated fatty acids" and "fatty acid biosynthesis" were closely related in the different color morphs. Furthermore, we performed comparative analysis of polysaccharide and saponin among white, green and purple A. japonicus. The results showed that the content of polysaccharide and saponin in purple A. japonicus was the highest, while that in white A. japonicus was the lowest. This study will provide valuable information for future studies on sea cucumber and the molecular mechanism underlying pigmentation and color polymorphism, and may contribute to support the culturing of desirable color morphs.

Cloning, Expression and Inhibitory Effects on Lewis Lung Carcinoma Cells of rAj-Tspin from Sea Cucumber (Apostichopus japonicus).

In recent years, sea cucumber has become a favorite healthcare food due to its characteristic prevention of cardiovascular diseases, suppression of tumors, as well as enhancement of immunity. In order to screen the anti-tumoral proteins or peptides from sea cucumber (Apostichopus japonicus), its cDNA library was analyzed, and a disintegrin-like and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13)-like was found. ADAMTS13-like contains 10 thrombospondin 1 (TSP1) domains. Based on analysis of bioinformatics, the third TSP1 domain of this protein, which is further named Aj-Tspin, contains an arginine-glycine-aspartate (RGD) motif. Since our previous studies showed that the recombinant RGD-containing peptide from lampreys showed anti-tumoral activity, the third TSP1 domain of ADAMTS13-like was chosen to evaluate it's effect on tumor proliferation and metastasis, despite the fact it shares almost no homologue with disintegrins from other species. After artificial synthesis, its cDNA sequence, Aj-Tspin, which is composed of 56 amino acids, was subcloned into a pET23b vector and expressed as a recombinant Aj-Tspin (rAj-Tspin) in a soluble form with a molecular weight of 6.976 kDa. Through affinity chromatography, rAj-Tspin was purified as a single protein. Both anti-proliferation and immunofluorescence assays showed that rAj-Tspin suppressed the proliferation of Lewis lung carcinoma (LLC) cells through apoptosis. Adhesion assay also displayed that rAj-Tspin inhibited the adhesion of LLC cells to ECM proteins, including fibronectin, laminin, vitronectin and collagen. Lastly, rAj-Tspin also suppressed the migration and invasion of LLC cells across the filter in transwells. Thus, the above indicates that rAj-Tspin might act as a potential anti-tumoral drug in the future and could also provide information on the nutritional value of sea cucumber.

Investigation of structural proteins in sea cucumber (Apostichopus japonicus) body wall.

Structural proteins play critical roles in the food quality, especially texture properties, of sea cucumbers and their products. Most of the previous studies on sea cucumbers focused on few individual proteins, which limited our understanding of how structural proteins influenced the quality of sea cucumbers. Inspired by the clarification of sea cucumber (Apostichopus japonicus) genome, we established an integrated data of structural proteins in the sea cucumber body wall. A portfolio of 2018 structural proteins was screened out from the sea cucumber annotated proteome by bioinformatics analysis. The portfolio was divided into three divisions, including extracellular matrix proteins, muscle proteins, and proteases, and further classified into 18 categories. The presence of 472 proteins in the sea cucumber body wall was confirmed by using a proteomics approach. Moreover, comparative proteomics analysis revealed the spatial distribution heterogeneity of structural proteins in the sea cucumber body wall at a molecular scale. This study suggested that future researches on sea cucumbers could be performed from an integrated perspective, which would reshape the component map of sea cucumber and provide novel insights into the understanding of how the food quality of sea cucumber was determined on a molecular level.

Deep-sea megabenthos communities of the Eurasian Central Arctic are influenced by ice-cover and sea-ice algal falls.

Quantitative camera surveys of benthic megafauna were carried out during the expedition ARK-XXVII/3 to the Eastern Central Arctic Basins with the research icebreaker Polarstern in summer 2012 (2 August-29 September). Nine transects were performed for the first time in deep-sea areas previously fully covered by ice, four of them in the Nansen Basin (3571-4066m) and five in the Amundsen Basin (4041-4384m). At seven of these stations benthic Agassiz trawls were taken near the camera tracks for species identification. Observed Arctic deep-sea megafauna was largely endemic. Several taxa showed a substantially greater depth or geographical range than previously assumed. Variations in the composition and structure of megabenthic communities were analysed and linked to several environmental variables, including state of the sea ice and phytodetritus supply to the seafloor. Three different types of communities were identified based on species dominating the biomass. Among these species were the actiniarian Bathyphellia margaritacea and the holothurians Elpidia heckeri and Kolga hyalina. Variations in megafaunal abundance were first of all related to the proximity to the marginal ice zone. Stations located closer to this zone were characterized by relatively high densities and biomass of B. margaritacea. Food supply was higher at these stations, as suggested by enhanced concentrations of pigments, organic carbon, bacterial cell abundances and nutrients in the sediments. Fully ice-covered stations closer to the North Pole and partially under multi-year ice were characterized by lower concentrations of the same biogeochemical indicators for food supply. These stations nevertheless hosted relatively high density and biomass of the holothurians E. heckeri or K. hyalina, which were observed to feed on large food falls of the sea-ice colonial diatom Melosira arctica. The link between the community structure of megafauna and the extent and condition of the Central Arctic sea-ice cover suggests that future climate changes may substantially affect deep ocean biodiversity.

Transcriptome analysis of body wall reveals growth difference between the largest and smallest individuals in the pure and hybrid populations of Apostichopus japonicus.

Long-term inbreeding of sea cucumber has resulted in a decrease in its growth rate, which has severely affected yield and economic efficiency. In this study, three Apostichopus japonicus families were constructed and screened into the weight of smallest and largest, which included Russian, Chinese, and their hybrids (RC). We examined the transcriptional profiles of hybrid (RC) and purebred (CC and RR). A total of 49.69 Gb clean reads were obtained, and the Q30 base percentage was above 90.47%. A total of 5191 novel genes were discovered, of which 2592 genes were annotated. Differentially expressed genes (DEGs) were identified, and functional annotation and enrichment analysis were performed. Approximately 1874 DEGs were screened in the Chinese sea cucumber (CC) difference group; 2591 DEGs were obtained in the hybrid sea cucumber difference group (RC), and 3006 DEGs were obtained in the Russian sea cucumber difference group (RR). In Gene Ontology (GO) analysis, highest DEG enrichment was observed for the functional categories of cellular process and metabolic process. In terms of cellular components, DEG enrichment was observed in cell part, cell; for molecular function, DEG enrichment was detected in catalytic activity, binding, hydrolase activity, transferase activity. According to the differential expression analysis, we found that 15 heat shock protein (HSP) genes that have the same expression trends, which were upregulated in the smallest weight of three sea cucumber lines. In addition, COG analysis of defense genes was conducted. All defense genes (ATP-binding cassette transporters (ABCs), multidrug resistance protein (MRPs), and beta-lactamase) showed the same expression trend, which was significantly upregulated in smallest individuals compared to that of largest individuals in RC lines, which implied the smallest individuals are exposed to more pressure during growth. These results may lead to the smallest individuals showing slow growth. Additionally, we selected 12 DEGs to validate the result by qPCR. Those DEGs were included in growth-related and resistance genes. Sequencing of the A. japonicus transcriptome improves our understanding of the transcriptional regulatory apparatus that controls individual development and growth.

A new ophiocistioid with soft-tissue preservation from the Silurian Herefordshire Lagerstätte, and the evolution of the holothurian body plan.

Reconstructing the evolutionary assembly of animal body plans is challenging when there are large morphological gaps between extant sister taxa, as in the case of echinozoans (echinoids and holothurians). However, the inclusion of extinct taxa can help bridge these gaps. Here we describe a new species of echinozoan, Sollasina cthulhu, from the Silurian Herefordshire Lagerstätte, UK. Sollasina cthulhu belongs to the ophiocistioids, an extinct group that shares characters with both echinoids and holothurians. Using physical-optical tomography and computer reconstruction, we visualize the internal anatomy of S. cthulhu in three dimensions, revealing inner soft tissues that we interpret as the ring canal, a key part of the water vascular system that was previously unknown in fossil echinozoans. Phylogenetic analyses strongly suggest that Sollasina and other ophiocistioids represent a paraphyletic group of stem holothurians, as previously hypothesized. This allows us to reconstruct the stepwise reduction of the skeleton during the assembly of the holothurian body plan, which may have been controlled by changes in the expression of biomineralization genes.

Molecular characterization and expression of NLRP10 in the antibacterial host defense of the sea cucumber (Apostichopus japonicus).

The nucleotide-binding oligomerization domain-like receptors (NOD-like receptors, NLRs) can regulate the innate immune process and is an important part of inflammatory body. In this study, we use transcriptome sequencing and the rapid amplification of cDNA ends approach to identify a novel NLRP gene in Apostichopus japonicus. We designated the gene as AjNLRP10. The full-length of AjNLRP10 is 4509 bp. The putative open reading frame comprising 3489 bp encodes a polypeptide with 1162 amino acid residues. The predicted molecular mass of AjNLRP10 is 132.87 kDa and its theoretical pI is 5.60. AjNLRP10 comprises a signal peptide with two Ig superfamily (IgSF) domains and a NACHT [NAIP (neuronal apoptosis inhibitory protein), CIITA (MHC class II transcription activator), HET-E (incompatibility locus protein from Podospora anserina) and TP1 (telomerase-associated protein)] domain. Spatial distribution expression analysis detected AjNLRP10 in all of the tissues tested, but with higher expression in the coelomocytes, medium expression in the intestine and respiratory tree, and slightly weaker expression in the body wall, tube feet, and longitudinal muscle. The expression levels of AjNLRP10 in the respiratory tree and intestines of sea cucumbers with skin ulceration syndrome were increased by 4-fold and 2.7-fold compared with those in healthy sea cucumbers, respectively. We investigated expression profiles of AjCasepase-1 (Cysteinyl aspartate specific proteinase-1) and AjMMP37 (mitochondrial protein-37) after AjNLRP10 knock-down and discovered that AjCasepase-1 was raised by 2.60-fold and AjMMP37 was raised by 3.84-fold. The study showed that AjNLRP10 has inhibitory effect in the immune process. In conclusion, this study showed that the AjNLRP10 protein found in the sea cucumber involved with the innate immune responses against bacterial infection. It has a similar structure and biological function to that in other organisms, where it appears to be involved with these results provide insights into the innate immune mechanism in the sea cucumber as well as suggesting new strategies for disease prevention, molecular therapy, and the development of novel drugs for sea cucumbers.

Pharmacological Potential of Sea Cucumbers.

This review presents a detailed analysis of published research data focused on the pharmacological activity exerted by biologically active compounds isolated from sea cucumbers belonging to the class of Holothuroidea, phylum Echinodermata. The review contains descriptions of the structure, physico-chemical properties and pharmacological effects of these active substances. Particular attention is given to compounds with anticoagulant, antithrombotic, antioxidant, anticancer, anti-infectious, immune-stimulating and anti-ACE (angiotensin converting enzyme) activities as well as to the substances exerting a regulating influence on lipid and carbohydrate metabolism. All these compounds may be considered as prototypes for development of new pharmaceutical substances and medicines.

Sea Cucumber Glycosides: Chemical Structures, Producing Species and Important Biological Properties.

Sea cucumbers belonging to echinoderm are traditionally used as tonic food in China and other Asian countries. They produce abundant biologically active triterpene glycosides. More than 300 triterpene glycosides have been isolated and characterized from various species of sea cucumbers, which are classified as holostane and nonholostane depending on the presence or absence of a specific structural unit γ(18,20)-lactone in the aglycone. Triterpene glycosides contain a carbohydrate chain up to six monosaccharide units mainly consisting of d-xylose, 3-O-methy-d-xylose, d-glucose, 3-O-methyl-d-glucose, and d-quinovose. Cytotoxicity is the common biological property of triterpene glycosides isolated from sea cucumbers. Besides cytotoxicity, triterpene glycosides also exhibit antifungal, antiviral and hemolytic activities. This review updates and summarizes our understanding on diverse chemical structures of triterpene glycosides from various species of sea cucumbers and their important biological activities. Mechanisms of action and structural-activity relationships (SARs) of sea cucumber glycosides are also discussed briefly.

Molecular phylogeny of extant Holothuroidea (Echinodermata).

Sea cucumbers (Holothuroidea) are a morphologically diverse, ecologically important, and economically valued clade of echinoderms; however, the understanding of the overall systematics of the group remains controversial. Here, we present a phylogeny of extant Holothuroidea assessed with maximum parsimony, maximum likelihood, and Bayesian approaches using approximately 4.3kb of mt- (COI, 16S, 12S) and nDNA (H3, 18S, 28S) sequences from 82 holothuroid terminals representing 23 of the 27 widely-accepted family-ranked taxa. Currently five holothuroid taxa of ordinal rank are accepted. We find that three of the five orders are non-monophyletic, and we revise the taxonomy of the groups accordingly. Apodida is sister to the rest of Holothuroidea, here considered Actinopoda. Within Actinopoda, Elasipodida in part is sister to the remaining Actinopoda. This latter clade, comprising holothuroids with respiratory trees, is now called Pneumonophora. The traditional Aspidochirotida is paraphyletic, with representatives from three orders (Molpadida, Dendrochirotida, and Elasipodida in part) nested within. Therefore, we discontinue the use of Aspidochirotida and instead erect Holothuriida as the sister group to the remaining Pneumonophora, here termed Neoholothuriida. We found four well-supported major clades in Neoholothuriida: Dendrochirotida, Molpadida and two new clades, Synallactida and Persiculida. The mapping of traditionally-used morphological characters in holothuroid systematics onto the phylogeny revealed marked homoplasy in most characters demonstrating that further taxonomic revision of Holothuroidea is required. Two time-tree analyses, one based on calibrations for uncontroversial crown group dates for Eleutherozoa, Echinozoa and Holothuroidea and another using these calibrations plus four more from within Holothuroidea, showed major discrepancies, suggesting that fossils of Holothuroidea may need reassessment in terms of placing these forms with existing crown clades.

Sublittoral and bathyal sea cucumbers (Echinodermata: Holothuroidea) from the Northern Mozambique Channel with description of six new species.

The 2009 expedition with the research vessel Miriky sampled the sublittoral and bathyal waters of the northern Mozambique Channel. This exploration campaign resulted in a small, but very diverse collection of holothuroids comprising 174 specimens representing 31 species, 18 genera, 10 families and 5 orders. Of these species, many were hitherto unknown for Madagascar or even for the Indian Ocean, and six, Bathyplotes aymeric sp. nov., Holothuria (Cystipus) yann sp. nov., Holothuria (Stauropora) bo sp. nov., Holothuria (Metriatyla) alex sp. nov., Holothuria (Theelothuria) cyrielle sp.nov., Molpadia thandari sp. nov., are new to science. Molpadia lenticulum (Cherbonnier & Féral, 1981) is a new combination. This contribution provides an illustrated and annotated overview of the poorly known, highly biodiverse, sublittoral and bathyal sea cucumber fauna of the northern Mozambique Channel. Our findings demonstrate how ignorant we are about the poorly explored habitats of our planet and therefore stress the urgent need for more explorations to such regions.

A new genus and a new species in the sea cucumber subfamily Colochirinae (Echinodermata: Holothuroidea: Dendrochirotida: Cucumariidae) in the Mediterranean Sea.

A new genus Hemiocnus is here erected to accommodate the Mediterranean dendrochirotid sea cucumber Cladodactyla syracusana Grube, currently classified, with some doubt, in the cucumariid genus Pseudocnella. At the same time a new cucumariid species, Hemiocnus rubrobrunneus, is described from some Tunisian material, misidentified as Pseudocnella syracusana (Grube), received from the United States National Museum. The new genus appears most closely related to Pseudocnella than to any other genus within the Colochirinae. Although its body wall ossicles resemble those of Pseudocnella spp. it differs in that the two ventral-most tentacles are reduced and in the presence of rosettes in the tentacles. P. syracusana also cannot be classified in Ocnus because of the presence of multi-layered, fir-cone shaped plates in the body wall, often with one end denticulate; such ossicles are lacking in the type species of the latter genus. The new species, Hemiocnus rubrobrunneus, on the other hand, shows some resemblance to H. syracusanus in its characteristic buttons and incomplete baskets, differing in its softer body wall, lack of fir-cone-shaped plates and in the presence of rosettes and complete baskets in the body wall. There are also some resemblances of the new species to the Mediterranean species of Ocnus viz. O. brunneus, O. planci and O. lacteus, but the soft nature of the body wall, shallow quadrilocular instead of deep trilocular baskets, and the presence of large knobbed plates in the anal region precludes its inclusion in this genus.

Structural characterization of fucosylated chondroitin sulfates from sea cucumbers Apostichopus japonicus and Actinopyga mauritiana.

Two samples of fucosylated chondroitin sulfate (FCS), AJ and AM, were isolated from holothurian species Apostichopus japonicus and Actinopyga mauritiana, respectively. Purification of FCS was performed by ion exchange chromatography followed by gel filtration. Structure of the biopolymers was elucidated using chemical and NMR spectroscopic methods. Both polysaccharides were shown to contain a typical chondroitin core built up of repeating disaccharide units →3)-ß-d-GalNAc-(1→4)-ß-d-GlcA-(1→ and decorated by sulfate groups and α-l-Fuc branches. Two polysaccharides were different in pattern of sulfation of GalNAc and fucosyl branches connected to O-3 of GlcA. The ratio of GalNAc4S6S:GalNAc4S for AJ was about 2:1, whereas for AM this value was approximately 1:1. AJ contained Fucp2S4S and Fucp3S4S residues linked to O-3 of GlcA in a ratio of 3:1, while for AM this ratio was 1:4. Small portions of Fucp4S units attached to O-3 of GlcA were also found in both polysaccharides. Moreover, in a structure of AM the presence of Fucp3S residues linked to O-6 of GalNAc were determined using the data of NMR spectra.

Acetylated Triterpene Glycosides and Their Biological Activity from Holothuroidea Reported in the Past Six Decades.

Sea cucumbers have been valued for many centuries as a tonic and functional food, dietary delicacies and important ingredients of traditional medicine in many Asian countries. An assortment of bioactive compounds has been described in sea cucumbers. The most important and abundant secondary metabolites from sea cucumbers are triterpene glycosides (saponins). Due to the wide range of their potential biological activities, these natural compounds have gained attention and this has led to their emergence as high value compounds with extended application in nutraceutical, cosmeceutical, medicinal and pharmaceutical products. They are characterized by bearing a wide spectrum of structures, such as sulfated, non-sulfated and acetylated glycosides. Over 700 triterpene glycosides have been reported from the Holothuroidea in which more than 145 are decorated with an acetoxy group having 38 different aglycones. The majority of sea cucumber triterpene glycosides are of the holostane type containing a C18 (20) lactone group and either Δ(7(8)) or Δ(9(11)) double bond in their genins. The acetoxy group is mainly connected to the C-16, C-22, C-23 and/or C-25 of their aglycone. Apparently, the presence of an acetoxy group, particularly at C-16 of the aglycone, plays a significant role in the bioactivity; including induction of caspase, apoptosis, cytotoxicity, anticancer, antifungal and antibacterial activities of these compounds. This manuscript highlights the structure of acetylated saponins, their biological activity, and their structure-activity relationships.

Fallaxosides C1, C2, D1 and D2, Unusual Oligosulfated Triterpene Glycosides from the Sea Cucumber Cucumariafallax (Cucumariidae, Dendrochirotida, Holothurioidea) and Taxonomic Status of this Animal.

Four hew triterpene glycosides, fallaxosides C, (1), C2 (2), D, (3) and D2 (4) along with the known cucumarioside A3-2 (5) and koreoside A (6) have-been isolated from the sea cucumber Cucumaria fallax (Cucumariidae, Dendrochirotida). Structures of the glycosides have been elucidated by 2D NMR spectroscopy and mass spectrometry. All of the glycosides are rare non-holostane derivatives having shortened side chains and contain pentasaccharide carbohydrate moieties with two or three sulfate groups. Structures of these triterpene glycosides and their comparison with those earlier isolated from Cucuniaria spp. and Pseudocnus dubiosus leoninus allow us to suggest that the present assignment of C. fallax to the genus Pseudocnus is not correct, and this species.should be assigned to the genus Cucumaria. Cytotoxic activity of glycosides 1-5 against the ascite form of mouse Ehrlich carcinoma cells and mouse spleen lymphocytes and hemolytic activity against mouse erythrocytes have been studied. The glycosides were expectedly not active in all the tests due to the absence of an 18(20)-lactone in their aglycones and the presence of several sulfate groups. There was one exception, cucumarioside A3-2 (5), which. demonstrated a weak cytotoxicity against lymphocytes and moderate hemolytic activity.

Taxonomic status of the three color variants in sea cucumber (Apostichopus japonicus): evidence from mitochondrial phylogenomic analyses.

Color variation in sea cucumber is one of the most crucial traits affecting price and taste in East Asian countries. However, the relationship and taxonomic status of the three color variants are still unclear. We used 14 samples that covered all three color variants and their geographic distributions, to construct the first phylogeny for the color variants based on the complete mitochondrial genome sequence and a number of tree-building methods (maximum parsimony (MP), maximum likelihood (ML), and Bayesian inference (BI)). The divergence times within color variants were estimated by the Bayesian molecular clock approach using the BEAST program. Our results showed that the color variants were not monophyletic in the well-resolved phylogenetic tree, which strongly refuted their separate species status. The molecular dating estimate revealed that the sea cucumber was a young group, which originated in the early Miocene period (22.03 mya) and rapidly diverged after the late Miocene period. It is interesting that individuals within each variant or geographic distribution were not always closely related and thus did not share a common origin. We propose that although they differ in body color, the three color morphs all belong to a single species of Apostichopus japonicus and the historical marine climate and the hydrographic complexity of the ocean currents could be responsible for their present distribution patterns.

A short biography of Hubert Ludwig and a note on the publication dates of his monograph Die Seewalzen (1889-1892).

The dates of publication of Hubert Ludwig's (1852-1913) comprehensive monograph Die Seewalzen [= Sea cucumbers] are reviewed. The precise publication dates of his volume, originally published in 16 fascicles and 8 parts/issues, delivered between 1889 and 1892, has been re-examined. Additionally, a short biographical note on Hubert Ludwig's life and a discussion of all new taxa introduced by him in his monograph is given.

Biodiversity and distribution of the southern African sea cucumbers (Echinodermata: Holothuroidea).

The history of the southern African holothuroid fauna south of the tropic of Capricorn, is updated and the biodiversity and distribution of the fauna discussed. All five currently recognized orders are represented, distributed over 24 families, 74 genera and 163 species. As many as 117 species are shelf forms comprising the following faunistic components : 36% Indo-Pacific, 12% West Indian Ocean, 1% Atlantic and 51% endemic. Four faunistic provinces are recognized : tropical Indo-Pacific Province on the east coast, extending to St Lucia in northern KwaZulu-Natal; the Subtropical (Natal) province, from this point to Port St. Johns in the Eastern Cape Province; the Warm Temperate (Agulhas) Province from this point to Cape Point in the Western Cape Province; and the Cold Temperate (Namaqua) from Cape Point to Walvis Bay in Namibia. Vertical distribution of the approximately 90 species collected from more than one locality is also given. The origin of the holothuroid fauna is briefly discussed and reiterated that the Indo-Pacific component moved in from the north mostly by way of the Mozambique-Agulhas Current. The origin of the endemic component is obscure but surmised that it is perhaps also of Indo-Pacific origin with negligible contribution from the Atlantic.