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

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58 SEM photos of harpacticoid copepods; from top to bottom: Pseudectinosoma reductum, Nitocrella pescei and Elaphoidella elaphoides (ca. 200x) ancient origin of the genus, which perhaps dates back to a period before the onset of continental drift in the Tertiary. Groundwater in alluvial aquifers also hosts endemic species like those of the genera Nitocrella, Parapseudoleptomesochra and Elaphoidella in much wider areas than in karstic environments. A particular feature of the genus Parastenocaris is that it fragmented into a myriad of species, most of which are known to inhabit only one or a few sites. Italy hosts 35 species - including those of the closely related genus Simplicaris - although many more species must still be described. Parastenocaris are the tiniest copepods (seldom longer than 3/10 of a mm), with worm-shaped bodies and small appendages, which enable them to wriggle through the minute fissures between sand and gravel grains in interstitial environments. ■ Bathynellaceans Bathynellaceans are an order of totally stygobiont syncarid malacostracans of extremely ancient origin; some researchers believe they diversified as long ago as the Palaeozoic in littoral coastal waters, lagoons and estuaries, from which they colonised continental waters before the supercontinent Bathynella skopljensis (ca. 15x) Pangaea fragmented, causing them to spread into groundwater. Although only hypothetical, this fascinating scenario describes bathynellaceans as true living fossils, and shows how research on the taxonomy of these stygobionts is closely associated with the great palaeogeographical events which modelled the Earth’s surface. About 170 species of bathynellaceans are known, all of small size (between 0.5 and 3.5 mm), anophthalmic and diaphanous, with elongated, sometimes worm-like bodies. They do not have shells or brood pouches like isopods, amphipods and thermosbaenaceans, and their last abdominal segment (called telson) is free; these characteristics clearly identify these malacostracans. Italian bathynellaceans are still little known and studied: the first Italian representative of this group (Anthrobathynella stammeri) was discovered in 1954 in the interstitial environment of the river Adige in Verona, and since then only a few species have been described, belonging to the genera Bathynella, Hexabathynella, Hispanobathynella, Meridiobathynella and Sardobathynella. They include exclusively hyporheic interstitial species and 59
60 those associated with percolating water in caves. They are stenothermal animals, sometimes living in cold waters, as they have recently been found at high altitudes in the Alps. ■ Thermosbaenaceans Thermosbenaceans, like bathynellaceans, are an order of very ancient malacostracans, with about 30 stygobiont species living in fresh and slightly brackish water from the Caribbean sector to the circum- Mediterranean area, eastern Africa, Monodella stygicola (ca. 15x) Asia, and Australia. This group clearly differs from other malacostracans, due to the dorsal egg pouch formed by the carapace. The evolution of thermosbaenaceans is probably associated with the retreat of the sea following uplift caused by plate tectonics. The species often live in isolated locations and are of great biogeographical interest. Their name is misleading, as it refers to thermal water: in fact, it derives from the first species described, which was collected in an African thermal spring. Italy hosts four species - three of which are endemic to the country - living in saturated aquifers. Limnosbaena finki is found in karstic and alluvial water in north-eastern Italy (it is distributed as far as Bosnia); Monodella stygicola only lives in karstic habitats, occasionally in alluvial aquifers, in Apulia; Tethysbaena argentarii is an endemic species of anchialine waters in the Grotta di Punta degli Stretti (Argentario Promontory, Tyrrhenian), and Tethysbaena siracusae is endemic to the karstic area of Porto Palo in south-eastern Sicily. Spelaeomysis bottazzii (ca. 1x) ■ Mysidaceans Mysidaceans, or opossum shrimps, are malacostracans generally living in sea or brackish water. In Italy, there are two stygobiont genera, Stygiomysis and Spelaeomysis, in anchialine and freshwater in karstic areas in Apulia. The Mediterranean area hosts a third stygobiont species, Troglomysis, in the Dinaric karst. These detrivorous and saprophagous animals are 2-3 cm long - thus, unusually large compared with other mysids - and are found in small lakes, seldom in flowing water. A euryhaline and eurythermal species, Spelaeomysis bottazzii, usually lives in anchialine habitats in south-eastern Italy, between the Gargano and Salento (Apulia), even in polluted water. Stygiomysis hydruntina is rare, and presumably lives further down, where the water-table recharges; so far, it has only been collected on the Ionian side of the province of Lecce. The two species may locally cohabit. Although electrophoretic analyses suggest that the species are of recent, perhaps Pliocene origin, similar species in Mexico, the Caribbean and eastern Africa imply a more ancient, Tethyan origin. ■ Isopods Woodlice are a very diversified order of malacostracan crustaceans, with more than 10,000 known species. They presumably colonised Italian groundwater from marine (cirolanids, microparasellids, microcerberids) and surface freshwater ancestors (asellotans and perhaps sphaeromatids). Each family is a microcosm in itself, Proasellus franciscoloi (ca. 6x) and their study reveals very interesting biogeographical aspects. Asellids. Almost all stygobiont species of this family are Italian endemics. Asellus cavernicolus lives in the river Timavo (Trieste Karst). Results from molecular studies reveal that it is a relict species deriving from pre-glacial colonisation of the Trieste Karst by an epigean species, Asellus aquaticus. In Italy, the genus Proasellus counts several surface as well as cavernicolous and interstitial species. The genus diversified into many phyletic lines, the taxonomy of which requires clarification: the group deminutus in north-eastern Italy; pavani in the central-eastern Pre-Alps; cavaticus in France, western Piedmont and Liguria, in karstic environments (P. cavaticus, P. franciscoloi), and the group patrizii, exclusive to Sardinian groundwater. In addition, there are many similar species: P. ligusticus, found from Liguria to the Apuan Alps, and P. acutianus, in Tuscany, Latium and the island of Elba are the most widely distributed 61
Page 1 and 2: Fauna FABIO STOCH Despite its inhos
Page 3 and 4: 44 45 Methods for sampling and anal
Page 5 and 6: 48 Shells of gastropods Iglica voba
Page 7 and 8: 52 collected in phreatic waters in
Page 9: 56 ● Cyclopoid copepods. So far,
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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