Authors: ENZO GORETTI, CATERINA MARCUCCI, ALESSANDRA DI VEROLI, ANGELISA FABRIZI, ELDA GAINO
Abstract: Freshwater oligochaetes are studied worldwide because of their relevance as bioindicators in aquatic ecosystems. Nevertheless, species identification is still difficult because it is mainly based on the male reproductive system. The morphology of the chaetae offers an additional set of characters and the fine organization of these elements can help in solving crucial aspects allowing specific attribution. In spite of this, somatic chaetae are poorly investigated under scanning electron microscopy (SEM). A SEM analysis of the chaetae has been carried out on the tubificids Branchiura sowerbyi, Limnodrilus hoffmeisteri, Tubifex tubifex, and Psammoryctides barbatus from Trasimeno and Piediluco lakes (Central Italy). In particular, the chaetal pattern of B. sowerbyi is comparable to that described for specimens from the tropical regions of Asia, and T. tubifex shows the chaetal pattern typical of the nominal species; the palmate chaetae of P. barbatus are characterized by 15-20 fringes, each of them with a distal end thinner and folded backwards. In addition, B. sowerbyi is the dominant species in Lake Trasimeno, whereas it is lacking in Lake Piediluco, where the tubificids are primarily represented by T. tubifex.
Keywords: Tubificids, chaetae, scanning electron microscopy
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