Susanna de Zio Grimaldi

Further Data on the Mediterranean Sea Tardigrade Fauna

Abstract Available information about Mediterranean tardigrades regards mainly the insular and peninsular Italian coasts, but also Malta, the Alboran Sea, Spain, France, Albania, Morocco, Algeria, Tunisia, Cyprus, and Lebanon. The Mediterranean Tardigrades, more than 70 species, are Heterotardigrada, mainly the order Arthrotardigrada with several families, and the order Echiniscoidea with only the family Echiniscoididae. Coralligenous detritus seems to be the most favourable kind of sediment in which the highest values of biodiversity are reached. Halechiniscidae is the most important family in the subtidal zone, whereas Batillipedidae are more frequent in the intertidal zone. A study of 4 submarine cave populations has been carried out. Neoarctidae and Neostygarctidae, considered as the most ancient families, have only been found in the Mediterranean Sea to date. This could mean that Arthrotardigrada originated in the old Thetys Sea from which the basin of the Mediterranean Sea was formed.

Meiobenthic biodiversity in areas of the Gulf of Taranto (Italy) exposed to high environmental impact

Biological and chemical parameters (meiofauna density and diversity, redox profiles) were investigated in relation to the environmental conditions of sediments in the Gulf of Taranto. Sediment cores were collected from 42 stations from −5 to −20 m depth, in 1995, 2000 and 2001. Meiofauna abundance and diversity were significantly lower in the Mar Piccolo, the area most heavily polluted by organic loads; in Mar Grande and Chiatona areas the same parameters showed slightly higher values. Eh profiles revealed anoxic conditions in coastal sediments impacted by industrial and sewage discharges. Meiofauna density ranged from 186 to 1370 individuals × 10 cm−2. Generally, over 80% of total meiofauna was composed of nematodes; the contribution of other taxa is much less important. The widespread presence of the lessepsian Chlorophyte Caulerpa racemosa since 1996, seemed to enhance the abundance of meiofauna, and increased microhabitat complexity, but reduced diversity of some taxa, such as the meiobenthic crustaceans. Comparing 2001–2002 data with 1995 (before C. racemosa invasion), the recent decrease of some groups (ostracods, amphipods, isopods, tanaids and cumaceans) was markedly evident. In conclusion, our findings confirm the chronically degraded environmental conditions in the Gulf of Taranto, and draw attention to the further contribution of C. racemosa invasion.

Heterotardigrada of Two Submarine Cavesin S. Domino Island (Tremiti Islands) in the Mediterranean Sea with the Description of Two New Species of Stygarctidae

Abstract Two new species of the marine tardigrade family Stygarctidae, Parastygarctus mediterranicus and Pseudostygarctus rugosus , were recorded during an investigation of the meiofauna of two subtidal caves in San Domino Island (Tremiti Archipelago) in July and October 1997, July and October 1998 and May 1999. The description of the two species is given, and their phylogenetic relationships within the subfamily Stygarctinae are discussed. Bioecological information on the tardigrade fauna of the two caves are also supplied.

Marine gastrotrichs from the Tremiti Archipelago in the southern Adriatic Sea, with the description of two new species of Urodasys

Abstract Twenty‐four macrodasyid and thirteen chaetonotid species of marine Gastrotricha are reported. Two of these species ‐ Urodasys apuliensis and U. bucinastylis ‐ are new, while the macrodasyid genus Crasiella is reported for the first time in Italy and the Mediterranean basin. Samples were taken at depths varying from 1 to 34 metres. Altogether, the number of species found was relatively high and comparable with the range of fauna found on the major Italian islands. A possible evolution of the reproductive system in the genus Urodasys is briefly discussed.

Diversity and dynamics of an interstitial Tardigrada population in the Meloria Shoals, Ligurian Sea, with a redescription of Batillipes similis (Heterotardigrada, Batillipedidae)

Abstract Quantitative samples of sediment for the study of the meiofau‐na were collected monthly beweenMar1996 andFeb1997 from a 7‐m‐deep site in the Meloria Shoals, Livorno Italy. In the Tuscan Shoals, 16 species of tardigrades were found belonging to the families Stygarctidae, Halechiniscidae, and Batillipedidae. Megastygarctides orbiculatus and Actinarctus doryphorus are reported for the first time in the Mediterranean Sea, and a re‐description of Batillipes similis is proposed. Global density of the Tardigrada population fluctuated between 8 ind./10 cm2 in May 1996 and 285 ind./10 cm2 in January 1997. The lowest value of the Shannon‐Wiener biodiversity index (H’ = 1.09) was found in September 1996, whereas the highest score (H’ = 2.46) was obtained inMar1996. Pielous evenness index (J) fluctuated between 0.40 and 0.88, values attained in January 1997 andMar1996, respectively. The study confirms the notion that the organogenic detritus of the Shoals represents a very favourable environment for meiofau...

Florarctinae of Asdhu Island, Maldives, Indian Ocean (Tardigrada, Heterotardigrada)

Abstract In a sample of coral sand from the intertidal zone of Asdhu Island, in the Male Nord Atoll of the Maldive Islands (Indian Ocean), three species of Florarctinae belonging to the two genera Florarctus and Wingstrandarctus were found. They are Florarctus hulingsi Renaud‐Mornant, 1976, Florarctus pulcher n. sp., and Wingstrandarctus corallinus Kristensen, 1984.

Neoarctus primigenius n. g., n. sp., a new Stygarctidae of the Tyrrhenian Sea (Tardigrada, Arthrotardigrada)

Abstract A new Stygarctidae, Neoarctus primigenius n.g., n.sp. is described. It has been found in the sandy detritus of a rocky bottom covered with green algae at ‐ 38 m depth in the Orosei Gulf off Sardinia (Tyrrhenian Sea). The most important characteristics of this species are the dorsal cuticular elements, the distribution of the cephalic sense organs in both the cephalic and scapular plates and the presence of three pairs of clavae. Taking into account the cuticular plates, the number and distribution of the sense organs, and the claw morphology, the affinities of this species with Oreellidae, Neostygarctidae and Renaudarctidae are here discussed.

A Comparison of Morphological Characters Within the Genus Rhomboarctus (Tardigrada: Heterotardigrada) with the Description of Two New Species

Two new species of marine arthrotardigrades:Rhomboarctus aslaki sp. n. and Rhomboarctus duplicicaudatus sp. n. (Tardigrada: Halechiniscidae) belonging to the genus Rhomboarctus Renaud-Mornant, 1984 are described from the North Atlantic Sea and the Mediterranean Sea, respectively. New features for the formerly monotypic genus are presented and a complete description of the buccal apparatus is given for the first time.

Pseudostygarctus apuliae (Tardigrada, Heterotardigrada): A new species from the lower Adriatic Sea

Abstract A new species of Stygarctidae, belonging to the genus Pseudostygarctus McKirdy et al., 1976, Pseudostygarctus apuliae, was found in subtidal sediments of Porto Colombo, near Bari (Adriatic Sea) and is described. The new species has intermediate characters between P. triungulatus McKirdy et al., 1976, and P. mirabilis de Zio Grimaldi et al., 1998. Its major distinctive traits are: the dorsal plates morphology and the cuticle sculpture.

Two new sub‐Antarctic Echiniscoididae from Marion Island (Heterotardigrada, Echiniscoidea)

Abstract Echiniscoides sigismundi verrucariae and E. sigismundi porphyrae, two new subspecies of Echiniscoides sigismundi sensu lato, from the intertidal zone of sub‐Antarctic Macaroni Bay in Marion Island are described. The two subspecies show important peculiarities in cuticle structure, claw number, and male and female gonopores.