Review of terminology for the outline of dorsal scutum in Laniatores (Arachnida, Opiliones)

Abstract

In many Opiliones (notably the Laniatores) the five most anterior opisthosomal tergites are fused with the carapace forming the so called dorsal scutum (DS) (Latreille 1804; Simon 1879; Hadži 1942) with a highly variable shape arising from multiple factors, such as differential development of musculature (especially of coxa IV), internal organs and influence of appendages (Loman 1903; Winkler 1957). The different degrees of fusion of the tergites were first studied by Hadži (1942), who proposed a terminology for them. This terminology was adopted and enhanced by Kratochvíl (1958) and Martens (1978). A shield formed by the fusion of the carapace with abdominal tergites I to V is called scutum magnum (Hadži 1942). The shield formed by the fusion of carapace with abdominal tergites I to VII is called scutum complexum (Kratochvíl 1958) and occurs in the males of Heteropachylinae Kury, 1994 (Kury 1994) and Paralolidae Kratochvíl, 1958 (Kratochvíl 1958). Finally, the scutum completum (Hadži 1942) is formed by the complete fusion of the carapace and abdominal scutum, formed by tergites I to VIII, and occurs in the Sandokanidae (Martens 1978). In this paper we focus on the different forms of the scutum magnum.