Archaias Montfort 1808

The type species of Archaias de Montfort, 1808 is Archaias spirans de Montfort, 1808 = Nautilus angulatus Fichtel and Moll, 1798, by original designation (De Montfort 1808: 191). Archaias spirans de Montfort is an objective synonym of Nautilus angulatus Fichtel and Moll, 1798.

Two other genera erected by De Montfort (1808), Ilotes and Helenis, are synonymized with Archaias, as their type species have been shown to represent different developmental stages of Archaias angulatus Fichtel and Moll, 1798. The type species of Ilotes de Montfort, 1808 is Ilotes rotalitus de Montfort, 1808 = Nautilus orbiculus Fichtel and Moll, 1798, by original designation (De Montfort 1808: 199). Nautilus orbiculus Fichtel and Moll, 1798, represents a juvenile stage of Nautilus angulatus, Fichtel and Moll, 1798, and is considered to be a subjective synonym of the latter species (Crapon de Caprona d'Ersu and Benier 1985, Cushman 1946, Lévy 1977, Loeblich and Tappan 1964, Loeblich and Tappan 1988, Rögl and Hansen 1984). The type species of Helenis de Montfort, 1808 is Helenis spatosus de Montfort, 1808 = Nautilus aduncus Fichtel and Moll, 1798, by original designation (De Montfort 1808: 195). Nautilus aduncus Fichtel and Moll, 1798, represents the adult flabelliform stage of Nautilus angulatus, Fichtel and Moll, 1798, and is considered to be a subjective synonym of the latter species (Crapon de Caprona d'Ersu and Benier 1985, Cushman 1946, Lévy 1977, Loeblich and Tappan 1964, Loeblich and Tappan 1988, Rögl and Hansen 1984).

The type specimens of Archaias angulatus, A. orbiculus, and A. aduncus are housed in the collections of the Department of Geology and Paleontology, Natural History Museum, Vienna, Austria (Rögl and Hansen 1984).

Test compressed, periphery rounded, early stage planispiral and involute, with a thickened central boss, chambers numerous, low and widening rapidly, equitant on the periphery, sutures strongly oblique and curved, later whorls flaring, peneropline, flabelliform or discoid, and chambers cyclical and evolute, interior of all but earliest chambers with cylindrical interseptal pillars, but no internal partitions or septula; wall calcareous, porcelaneous, early chambers perforate, later with surface pits or pseudopores; aperture in the early stage a basal slit, in the adult two to four rows of pores on the truncate apertural face are interspersed between the internal pillars, occupying much or all of the test circumference. Miocene to Holocene; cosmopolitan. (Loeblich & Tappan, 1987, Foraminiferal Genera and Their Classification)