Three Penicillium strains having the excellent ability to produce indole alkaloids in surface and submerged cultures were isolated from the air of the circumferance of laboratory. These strains were all identified as Penicillium concavo-rugulosum ABE. By selection of the strains and modifying the medium, the total alkaloid yield in surface cultures could be increased up to ca. 1000 mg alkaloids per 10 cultures (culture filtrate 1.35 liter, and the mycelium 15 g, based on dry weight). From these cultures, a hitherto known ergot alkaloid chanoclavine-(I) and, further, two new interconvertible alkaloids, rugulovasine A and B, have been isolated in good yields. Rugulovasine A crystallized from benzene as colorless prisms ; C16H16O2N2, mp 138°C (decomp.), [α]22D 0°, [α]22546 0° (c=0.5, pyridine). Rugulovasine B separated from benzene as colorless resinous oil; C16H16O2N2, [α]22D 0°, [α]22546 0° (c=0.5, pyridine). It yielded crystalline salts : the hydrochloride, C16H16O2N2•HCl•H2O, white prisms from water, mp 187°C (decomp.), [α]22D 0° (c=0.5, pyridine) ; the oxalate, C16H16O2N2•1/2 C2H2O4, colorless prisms from water, mp 217°C (decomp.), [α]22D 0° (c=0.5, pyridine). Both rugulovasine A and B gave reddish purple color, turning into bluish purple color with Allport and Cocking's reagent. They were reversibly converted into each other in various organic solvents, especially in alcohols. They were considered to be the chanoclavine type of new ergot alkaloid isomers, containing an opened D ring and an unsaturated lactone ring in their molecules. The rugulovasines have been found with chanoclavine-(I) also in the cultures of various molds, such as Penicillium rugulosum, Corticium caeruleum, Pellicularia filamentosa, etc., besides Penicillium concavo-rugulosum. © 1969, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.