Original paper
Auxospore structure and development in Toxarium sp.
Kaczmarska, Irena; Ehrman, James M.; Samanta, Brajogopal
Nova Hedwigia Band 120 Heft 1-4 (2025), p. 577 - 590
22 references
published: Apr 30, 2025
published online: Feb 6, 2025
manuscript accepted: Oct 14, 2024
manuscript received: Oct 14, 2024
DOI: 10.1127/nova_hedwigia/2025/1101
ArtNo. ESP050012031024, Price: 29.00 €
Abstract
The structure and development of the auxospore in Toxarium sp. was found to be similar to that of a more derived member of the order Ardissoneales, Synedrosphenia crystallina. The basic design, therefore, has been conserved in this order, even though the structure and patterning of the vegetative valves is so different that the member genera had traditionally been assigned to different orders. This confirms our earlier notion that the exceptionally elongated Ardissoneales evolved their own, non-pennate process of producing tubular auxospores and bilateral valves. Although similar, the auxospore wall structure in Toxarium sp. was not identical to S. crystallina. In Toxarium, a greater abundance and wider diversity of scales participate in building the auxospore walls compared to Synedrosphenia. Furthermore, before fully silicified, the perpendicular transverse closed perizonial bands in Toxarium clearly revealed themselves as consisting of a fused string of radially perforated scales, they are the scaly bands. We also document structures we named protothecae that are parts of the earliest cell wall of the sexual progeny, likely setting the formative parameters for the functional initial valve. These structures are different from longitudinal perizonia, which are components of the auxospore wall, not the progeny.
Keywords
tubular auxospore • mediophytes • scaly transverse perizonial band • protovalve • vincula • incunabular scales