Despite its inhospitable appearance and lack of any ... - Udine Cultura

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50 Alkaline waters in karstic caves in Gorizia and Trieste host the second Italian stygobiont polichaete, Marifugia cavatica. It belongs to the serpulids, which are marine polychaete worms living in limestone tubules. Marifugia cavatica, probably a micro-filterer, forms dense colonies that occasionally carpet extensive areas of walls of underground streams with tubules up to 1 cm long. The Marifugia formation is a little-known microhabitat rich in microfauna (protozoans, gastropods, oligochaetes, copepods, isopods and amphipods) that populates, like the colonies of marine serpulids, the complex mosaic of spaces between tubules. The species lives in the Dinaric region as far as Albania, together with other species of ancient marine origin, like isopods of the genus Sphaeromides and amphipods of the genus Hadzia, of probable Tertiary origin. ■ Oligochaetes Oligochaetes are freshwater and marine terrestrial annelids whose bodies are made up of segments (metameres) without appendages, with rows of transversal, movable bristles (setae). The shape and distribution of the setae play an important role in the taxonomy of this group. Earthworms are usually detrivorous and microphagous, and colonise microhabitats rich in organic matter. In Italian groundwater, the most common are the lumbriculid and Troglochaetus beranecki (ca.50x) Cernosvitoviella sp. (ca. 40x) tubificid families, together with the aquatic and semi-aquatic species of enchytraeids. The identity and similarity of groundwater oligochaetes have only recently been partially established, and research is beginning. The main problem in defining an oligochaete as stygobiont lies in the fact that many surface species (living in sediments of surface water and sometimes in humid soil) are pre-adapted to life in hypogean habitats (they are depigmented and anophthalmic). It is common practice to define as stygobiont those species which, as far as is known today, have exclusively been found in groundwater. The parvidrilid family is certainly the most interesting among the taxa recently found in Italy, from the Pre-Alps to Sardinia. So far, all records have been ascribed to the same species, Parvidrilus spelaeus. They are exclusive inhabitants of vadose zones in Italian caves, where they colonise the silty, muddy sediments on the bottom of concretions, pools of trickling water and interstices of hypogean streams. Presumably, the family has an ancient marine origin. Among the numerous species of tubificids found in Italian groundwater, there are the genera Haber (H. monfalconensis in springs of the Julian Pre-Alps and Trieste Karst, and H. zavreli in groundwater in Umbria and Emilia Romagna), two endemics of the genus Rhyacodrilus, recently described (R. gasparoi in Pre-Alpine caves and R. dolcei in small concretions of the Trieste Karst), Tubifex pescei, in phreatic waters of Umbria and Marches, Abyssidrilus cuspis, 51
52 collected in phreatic waters in Umbria and caves of Liguria and Friuli Venezia Giulia, Sketodrilus flabellisetosus in the Trieste Karst, and Aktedrilus ruffoi, recently described on specimens found in interstitial environments of the river Tione (Verona). Enchytraeids are less well-known, and several species of Cernosvitoviella, found in Pre-Alpine caves and considered to be stygobionts, are still being examined. ■ Ostracods Ostracods (from the Greek ostrakon, shell) are a diversified group of small crustaceans, whose body is enclosed by a bivalve carapace made of calcite, their unmistakable characteristic. Their carapace may be egg-, bean- or trapezoid-shaped, and is often knobbly or dimpled. The number and shape of their appendages is generally the same. Freshwater species have eight pairs of appendages, four of which are cephalic (antennules, antennae, mandibles, and maxillulae), three thoracic, and one caudal (uropod). They are generally small-sized (stygobionts seldom exceed 1 mm in length), and are found in all types of surface- and groundwater. Despite their large numbers in groundwater, both in caves and alluvial aquifers, stygobiont mussel shrimps are little known in Italy, and many Cypria cavernae (ca. 100x) Pseudolimnocythere sp. aff. hypogea (ca. 100x) species are still being studied. Among the most interesting is Cypria cavernae, thought to be endemic to alkaline karstic waters in Gorizia, Trieste and Slovenia. Other species are associated with anchialine habitats, like those in underground lakes of coastal caves in the Salento in Apulia (Trapezicandona stammeri, Pseudolimnocythere hypogea). Specimens of the genus Pseudolimnocythere were found in the brackish water of the Poiano springs, which issue from Triassic evaporites in the upper Val Secchia. A very interesting genus from the palaeogeographical viewpoint is Sphaeromicola. It is a commensal species living exclusively on stygobiont isopod crustaceans of the genera Monolistra (Sphaeromicola stammeri, in the Pre-Alps) and Sphaeromides (Sphaeromicola sphaeromidicola, in the Isonzo Karst). The same genus includes a commensal species on marine amphipod crustaceans, showing how both these ostracods and their hosts had marine ancestors. Mussel shrimps are very interesting in palaeogeographical research, because their shells are easily conserved in sediments, where they fossilise. The large numbers of fossil species, together with the great diversity of living ones, provide detailed information about the evolution of the animals of this class. Unfortunately, since stygobiont species are little known, have rarely been used to analyse the origin and evolution of stygobiont fauna. 53
Page 1 and 2: Fauna FABIO STOCH Despite its inhos
Page 3 and 4: 44 45 Methods for sampling and anal
Page 5: 48 Shells of gastropods Iglica voba
Page 9 and 10: 56 ● Cyclopoid copepods. So far,
Page 11 and 12: 60 those associated with percolatin
Page 13 and 14: 64 Species of genus Niphargus; top:
Page 15 and 16: 68 ■ Decapods Italian fauna has o
Page 17 and 18: 72 Stygofaunal provinces in Italy T
Page 19 and 20: 76 aquifers in the Sabini mountains
Page 21 and 22: 80 ■ The ecology of aquifers Acco
Page 23 and 24: 84 85 The discovery of a new submer
Page 25 and 26: 88 anastomoses, often adjacent to t
Page 27 and 28: 92 93 The saline springs of Poiano:
Page 29 and 30: 96 Modified sensory setae on the an
Page 31 and 32: 100 Theoretical evolutionary sequen
Page 33 and 34: 104 Sketch showing degrading phases
Page 35 and 36: 108 109 Stygodiversity in the Presc
Page 37: 112 animal groups still living on t

Despite its inhospitable appearance and lack of any ... - Udine Cultura

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