European marine Mollusca: notes on less well-known species. V. Cingula (Setia) macilenta (Monterosato, 1880) and Rissoa concinnata Jeffreys, 1883

During our studies of material, dredged in the central Mediterranean area, some samples rather frequently contained a very small rissoid, apparently related to both Cingula (s.l.) intersecta (Wood, 1856) [= C. obtusa (Cantraine, 1842), non Rissoa obtusa Brown, 1841 = Putilla (Obtusella) cantrainei Nordsieck, 1972], and Cingula (Setia) turriculata (Monterosato, 1884). Further study and comparison with samples from both the USNM¹ and BM¹ showed the species in question to be Rissoa concinnata Jeffreys, 1883 [compared with syntypes USNM 202239 and 182860, see Waren (1980: 22)]. At the same time, however, we found a sample of specimens belonging to the same species in the British Museum (BM 1911.10.26.24564-570) with a label in Monterosato’s hand: “Setia macilenta /Palermo”. Although recent literature on the latter, little known, nominal taxon [Nordsieck (1972: 157) and Priolo (1953:135)] gives the original dates of publication as 1917 and 1884, respectively, it turns out that Monterosato described Setia macilenta in 1880 (Monterosato, 1880: 69), in the following words: “Somiglia alla S. obtusa, Cantr., ma non è striata, è più conica, acuta e con la sotura più profonda. Labbro tagliente invece d’ingrossato”. Notwithstanding the fact that Monterosato (1884a, b) mentions both Cingulina concinnata (1884a: 281; 1884b: 67) and Pseudosetia macilenta (1884a: 281; 1884b: 75), there can be no doubt that both names refer to the same species. It is true that both Jeffreys and Monterosato describe this species as smooth, whereas in reality many specimens show very fine spiral lines, which might be the cause for confusion on Monterosato’s part. Also Watson (1886: 606) has pointed out the presence of spiral “sculpture” in R. concinnata. Although Monterosato (1880: 69) first described this species as Setia macilenta and later on (1884b: 75) placed it in the (sub)genus Pseudosetia, we consider the differences with Cingula (Setia) turriculata and Cingula (Setia) pulcherrima (Jeffreys, 1848) to be of a specific nature only and thus conclude for the same reasons as given earlier (Van Aartsen & Verduin, 1978: 28) that the correct name must be Cingula (Setia) macilenta (Monterosato, 1880). Rissoa concinnata Jeffreys, 1883 is a junior synonym.