A new marine gastrotrich from the State of São Paulo (Brazil), with a key to species of Pseudostomella (Gastrotricha, Thaumastodermatidae)

In previous papers, faunistic and preliminary taxonomic data on the gastrotrich communities along the coastline of the Brazilian states of São Paulo and Rio de Janeiro were reported; among the over 40 records, the occurrence of several species new to science was highlighted. One of such new taxa is described here based on observation carried out on living and SEM prepared specimens. Pseudostomella dolichopoda sp. n. (Gastrotricha: Thaumastodermatidae) is the only species in the genus that attains 420 μm in total length, is covered by pentancres and possesses, among others, caudal pedicles up to 45 μm in length. Additional differences with co-generic taxa characterized by a pentancrous covering are discussed. Furthermore, a key to the described Pseudostomella species of the world based on easily discernible traits, visible in both living and formalin-fixed specimens, is provided

A new non-naked species of Ptychostomella (Gastrotricha) from Brazil

A new species of marine Gastrotricha from Brazil is described and discussed. Ptychostomella lamelliphora sp. n. is one of the several new taxa that were found during an extensive survey of the gastrotrich fauna carried out in 2002 and 2003 along the coastline of the State of São Paulo. The new species is unique in that it possesses cuticular ornamentations in the form of plate-like structures (scales) along the lateral borders of the body and two massive clusters of densely packed adhesive tubes on the ventral surface, near the ano-genital opening. Both these features appear to be adaptations to challenge the high energy waters that characterize the species’ microhabitat: the coarse sublittoral sand in the channel between the mainland and the largest island in the State, Ihlabela. Additionally, a key to the described Ptychostomella species of the world is provided

An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)

Background Gastrotricha systematics is in a state of flux mainly due to the conflicts between cladistic studies base on molecular markers and the classical systematisation based on morphological traits. In sandy samples from Thailand, we found numerous macrodasyidan gastrotrichs belonging to an undescribed species of difficult taxonomic affiliation. The abundance and original nature of the specimens prompted us to undertake a deep survey of both morphological and molecular traits aiming at a reliable systematisation of the new taxon. Methodology/Principal Findings Using several microscopical techniques we investigated the external and internal anatomy, including the muscular and nervous systems of the new species. Additional specimens were used to obtain the 18S rRNA gene sequence; molecular data was analysed cladistically in conjunction with data from additional species belonging to the near complete Macrodasyida taxonomic spectrum. Specimens are vermiform, up to 806 \u3bcm in total length, and show a well-defined head equipped with peculiar leaf-like sensorial organs and a singlelobed posterior end. The adhesive apparatus includes anterior, ventrolateral, dorsal and posterior tubes. Pharynx is about 1/4 of the total length and shows pores at its posterior 3/4. Adult specimens exhibit maturing eggs and a bulky, muscular caudal organ, but do not show sperm nor the frontal organ. Musculature and nervous system organisation resemble the usual macrodasyidan plan; however, the somatic circular muscles of the intestinal region surround all other muscular components and a third FMRFamide-IR commissure ventral to the pintestinal junction appear to be an autoapomorphic traits of the new species. Conclusions/Significance While the anatomical characteristics of the Asian specimens appear so unique to grant the establishment of a new taxon, for which the name Thaidasys tongiorgii gen. et sp. nov. is proposed, the result of phylogenetic analyses based on the 18S rRNA gene unites the new genus with the family Macrodasyidae

Reproductive system of the genus Crasiella (Gastrotricha, Macrodasyida)

Crasiella diplura from Sweden and Crasiella sp. from Italy were studied alive and with transmission electron microscopy (TEM). The two species are simultaneous hermaphrodites and share the same reproductive system lay-out: paired ovaries extend along the posterior part of the intestine and join mid-dorsally, while bilateral,club-shaped testes lie at the sides of the anterior gut, extending as deferentia that fuse on the mid-ventral plane and open into a single pore; gametes mature in a caudocephalicand centripetal direction. The bulky, sac-like, frontal organ is lined by a simple epithelium and lies dorsolaterally to the intestine, on the left side of the body.The spindle-shaped caudal organ is musculo-glandular and is located ventrolaterally to the gut on the right side. It is characterized by the presence of a roughly Y-shapedinternal channel that opens into two pores close to each other, which function for the intake and outlet of the (auto)sperm, respectively. The spermatozoa, which arepeculiar and similar in the two species, are characterized by a long and complex acrosome consisting of four ultrastructurally distinct regions, three of which findequivalence in other gastrotrich species. The flagellum lacks a striated cylinder. Anatomy and ultrastructure enable us to hypothesize a modality of sperm transfer in Crasiellathat is similar to that observed in Macrodasys

Faunistics and zoogeographical overview of the Mediterranean and Black Sea marine Gastrotricha.

The paper provides an updated overview of the knowledge regarding the marine gastrotrich fauna of 10 Mediterranean and 2 Black Sea countries. Taxonomic account and species distribution come from published records, including electronically disseminated information, as well as original data from 18 localities (16 western and 2 levantine), investigated by the authors between 1990 and 2002. Since the description of the first marine Mediterranean gastrotrich, Emydasys agaso Claparede, 1867, discovered in the Gulf of Naples (Italy), 273 additional species, from 417 locations have been recorded in the basin so far. Of the gastrotrichs found, 143 species, in 24 genera and 6 families, belong to the order Macrodasyida and 131 species, in 11 genera and 3 families, belong to the order Chaetonotida; these statistics include several species as of yet not described. The number of species per location is variable, ranging from 1-37, with a global mean of 8.04 \uf0b1 6.69 spp/location. Egypt and Israel show mean values well above the average, with 12.8 and 10.8 spp/loc. respectively, whereas mean values for Algeria, Tunisia, Bulgaria, Croatia, and France are below average (1- 5.43 spp /location); data for Cyprus, Greece, Romania and Italy are within the average value. Acanthodasys aculeatus, recorded in 28% of the investigated location is the most frequently found macrodasyidan; Halichaetonotus aculifer, also recorded in 28% of the investigated localities, is the most common chaetonotidan whereas. Data analysis indicated substantial differences among countries, regarding sampling effort and, consequently, faunistic knowledge. In comparison with the generally good information concerning the Italian fauna (177 species from 246 localities), gastrotrichs from other Mediterranean nations are much less known; along with Italy, only few other Nations have been investigated to a sufficient extent (i.e., Greece: 44 sampled localities, 77 recorded species; France: 37 L, 70 spp; Egypt: 28 L, 81 spp; Israel: 15 L, 55 spp; Cyprus: 9 L, 41 spp), whereas investigation carried out in several other countries can be considered, to a variable degree, incomplete (i.e., Algeria: 16 investigated localities and 11 species found; Romania: 7 L, 30 spp; Tunisia: 5 L, 2 spp; Bulgaria: 3 L, 11 spp; Croatia: 1 L, 12 spp, Spain: 1 L, 3 sp, Malta; 2L, 2 spp.), or nil (e.g., Morocco, Libya, Turkey, Albania). All marine gastrotrich families and most marine genera have representatives in the Mediterranean fauna, notable absences regard the genera Desmodasys, Dinodasys, Planodasys, Prostobuccantia and perhaps Pseudoturbanella; on the other hand representatives of two genera, Emydasys and Dendropodola, are unknown elsewhere in the world except the western Mediterranean. At species level, about 140 taxa have so far been found only in the Mediterranean area, whereas the remainder have some north-Atlantic connections, including several considered as regional cosmopolitans (i.e., reported from at least two Oceans). Within the Mediterranean, the species geographic distribution does not appear to be homogeneous, with several taxa restricted to either the western or to the levantine basin; yet, Italy, Egypt and Israel show the highest numbers of endemic species, 70, 24 and 14 respectively, whereas only one species seems restricted to the Black Sea. A cluster analysis using the Bray-Curtis presence-absence similarity value to examine the relationship between 11 geographic areas, shows a clear separation between the Black Sea and the Mediterranean regions and within this, the Algerian-Tunisian region is separated from and the remaining 9 areas. The latter appear arranged in two main clusters, one including the southern Levantine regions (i.e., Egypt, Israel and Cyprus), the other containing regions of the north-western basin, the Adriatic sea and the two Greek sub-regions. In this cluster, the region comprising coastal France and Formentera (Spain) appears separated from the one containing, arranged into two distinct subsets, the Italian and the Greek areas. However, due to the paucity of information, data from key-areas is urged to confirm or disprove our current perception about numbers and distribution of gastrotrich taxa within the Mediterranean and the Black Sea

First records of Gastrotricha from South Africa, with description of a new species of Halichaetonotus (Chaetonotida, Chaetonotidae)

During a survey of the biota of the St. Lucia Estuary in the iSimangaliso Wetland Park, South Africa, a number of Gastrotricha were found among samples of meiofauna. Fresh, marine sediment yielded several specimens belonging to a total of seven species. Of these, two are already known from other regions (i.e., Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described as new to science (Halichaetonotussanctaeluciae sp. n.), while the remaining four (Pseudostomella sp., Halichaetonotus sp.1, Halichaetonotus sp. 2, Xenotrichula sp.) require further collections and analysis, in order to establish the extent of their affiliation to species already described. General appearance, shape of hydrofoil scale and the occurrenceof three long spines on the dorsal side make the new species most closely related to H. australis and H. marivagus. The key differences from these taxa and between Halichaetonotus sanctaeluciae sp. n. and H. aculifer are discussed

Fauna Europaea: Gastrotricha

Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. Gastrotricha are a meiobenthic phylum composed of 813 species known so far (2 orders, 17 families) of free-living microinvertebrates commonly present and actively moving on and into sediments of aquatic ecosystems, 339 of which live in fresh and brackish waters. The Fauna Europaea database includes 214 species of Chaetonotida (4 families) plus a single species of Macrodasyida incertae sedis. This paper deals with the 224 European freshwater species known so far, 9 of which, all of Chaetonotida, have been described subsequently and will be included in the next database version. Basic information on their biology and ecology are summarized, and a list of selected, main references is given. As a general conclusion the gastrotrich fauna from Europe is the best known compared with that of other continents, but shows some important gaps of knowledge in Eastern and Southern regions

Bioturbation beyond Earth: potential, methods and models of astroichnology

Traces – burrows, borings, footprints – are important evidences of biological behaviour on Earth, yet they received relatively little attention in the field of astrobiology. This study aims to discuss the application of ichnology (i.e. the study of life activity traces) to the search for past and modern life beyond Earth (i.e. herein called Astroichnology)

Meiofauna from the Meloria Shoals: Gastrotricha, biodiversity and seasonal dynamics

The gastotrichs taxocene from the Meloria Shoals was studied over one year period from four sets of samples each consisting of four replicate cores filled with 15 cni' of coarse organogenic sand. San2ples avere taken from a bottoni pit, at 7.0 m water depth, three months apart each other. Faunal analysis yielded 18 species and mean density of 228 ind/core. The highest number o.fspecies, 16, occurred in Ju1y while the Shannon- Wiener entropy (H') peaked in October (2.112). Diplodasys ankeli and Platydasys ruber resulted as the most abundant taxa throughout the study except in January when Platydasy ocellatus became the dominant species. species richness and high biodiversity of the locai meiofauna make the shallow Meloria shoals a place of great naturalistic value, worth to be preserved

Il popolo della sabbia

vengono escritti ed illustrati mediante foto al microscopio elettronico a scansione gli oranismi meiobentonici rinvenuti nelle secche della Meloria