Morphological characteristics of Ancylus fluviatilis O. F. Müller, 1774 (Gastropoda, Planorbidae)

Abstract

Glavni cilj ovog rada bio je usporediti morfološke značajke dviju populacija slatkovodnog puža Ancylus fluviatilis te utvrditi razlike i sličnosti u mjerenim vrijednostima. Jedna populacija uzorkovana je u rijeci Rudi (Dalmacija) koja pripada jadranskom slijevu, a druga u potoku Slapnica (Žumberak) koja pripada crnomorskom slijevu. Na oba lokaliteta jedinke su ručno skupljane s kamenja i valutica na koje su bile pričvršćene. Za određivanje morfoloških značajki vrste iz svake populacije odabrano je 110 jedinki kojima su izmjerene četiri morfometrijske značajke kućice (duljina, visina, anteriorna širina, posteriorna širina) te je određena suha i mokra masa jedinke. Osim toga, analizirano je i pet omjera morfoloških značajki kućice. Deskriptivna statistika mjerenih značajki pokazala je da jedinke uzorkovane u Rudi imaju manje kućice u usporedbi s puževima iz Slapnice. Prema rezultatima t-testa sve morfološke značajke, omjeri visine i duljine kućice, kao i omjeri visine i anteriorne širine kućice statistički se značajno razlikuju između dvije populacije. Visoke vrijednosti Pearsonovog koeficijenta korelacije za sve mjerene morfometrijske značajke pokazuju da je korelacija gotovo potpuna. Najjača linearna povezanost među mjerenim obilježjima populacije puževa u rijeci Rudi uočena je između duljine i anteriorne širine kućice (koeficijent determinacije linearnog regresijskog modela R² = 0,939). Za rijeku Slapnicu najjača je linearna povezanost uočena između duljine kućice i suhe mase jedinke (R² = 0,862).The main objective of this study was comparison of the morphological characteristics of the two populations of freshwater snail Ancylus fluviatilis and to determine differences and similarities between measured values. One snail population was sampled from Ruda River (Dalmacija) which belongs to the Adriatic basin and the second population was sampled from stream Slapnica which belongs to the basin of Black Sea. At both sites individuals were manually collected from rocks and pebbles. To determine the morphological characteristics of species, 110 individuals were selected from each of the two populations. For each of the individuals, four morphometric values of the shell were measured (length, height, anterir width, posterior width), as well as their dry and wet mass. Five morphometric ratios of shell were also calculated. Descriptive statistics indicated that the individuals sampled from Ruda River have smaller shells compared to snails from stream Slapnica. According to the results of t-test, all the morphological features and ratios between shell height and shell length, as well as ratios between shell height and shell anterior width were significantly different among two populations. The high value of Pearson correlation coefficient for all measured morphometric features indicated that the correlation was almost perfect. The strongest linear relationship among the measured characteristics of the snail population in the river Ruda was observed between the shell length and shell anterior width (coefficient of determination R² = 0,939). For stream Slapnica the strongest linear relationship was observed between the shell length and its dry mass (R² = 0,862)