The Carboniferous conodont Lochriea commutata (Branson and Mehl, 1941), the type species of Lochriea Scott, 1942: nomenclatural history, apparatus composition and effects on Lochriea species

Abstract

AbstractLochriea commutata (Branson and Mehl, 1941), a senior subjective synonym of Lochriea montanaensis Scott, 1942, is the type species of Lochriea Scott, 1942, one of the first conodont genera named using bedding-plane assemblages. Lochriea commutata is both wide- and long-ranging, locally stratigraphically important, and a consistently recognized Carboniferous species, despite its taxonomic journey from Spathognathodus to Gnathodus to Paragnathodus to Lochriea.Lochriea commutata was, as Lochriea montanaensis, initially reported to contain 22+ elements, the apparatus composition of the genus being subsequently amended to 17+ elements based on Lochriea wellsi Melton and Scott, 1973, which is an untenable hypothesis because the latter was a conodontophage. Restudy of original and new bedding-plane assemblages in the mid 1970s established that the first assemblages studied were fecal, the initial reconstruction incorporated elements of two individuals, and Lochriea commutata possessed a feeding apparatus of 2P1, 2P2, 2M, 2S1, 2S2, 2S3, 2S4, and 1S0 elements. A Lochriea sp. bedding-plane assemblage was subsequently found to have the same element composition, and restudy of type material, available bedding-plane assemblages, and new fused clusters confirms that Lochriea commutata had a 15-element ozarkodinid apparatus.While species are still assigned to Lochriea using carminiscaphate P1 elements almost exclusively, those assignments must be considered tentative until their apparatuses are determined to be similar to that of L. commutata, and until characteristics of elements other than the P1 element, particularly the makellate M element and the bipennate S3/4 element, are also taken into account.Lochriea bigsnowyensis Scott, 1942 is reassigned to Cavusgnathus Harris and Hollingsworth, 1933.