Diatoma

Diatoma is a genus of diatoms, a group of photosynthetic, unicellular algae with silica cell walls. In modern taxonomy, diatoms are placed in the phylum Bacillariophyta within the heterokont lineage. The genus Diatoma includes several species that inhabit freshwater environments and, less commonly, brackish or marine habitats. Members are typically small to medium-sized and occur as solitary cells or as part of biofilms on submerged surfaces.

Morphology: Diatom frustules are composed of two halves that fit together like a box and lid. Diatoma species display elongated to rectangular valve outlines with distinct ornamentation patterns. These silica features, observed by light and scanning electron microscopy, are used to differentiate species.

Distribution and ecology: Diatoma is widely distributed in rivers, lakes, wetlands, springs, and other moist habitats around the world. They contribute to primary production as part of the phytoplankton and microphytobenthos, often attaching to substrates via mucilaginous pads. Their abundance and composition can reflect environmental conditions such as nutrient status and salinity.

Reproduction and fossil record: Like other diatoms, Diatoma reproduces primarily by asexual division, which causes progressive size reduction until sexual reproduction occurs to restore cell size. Diatom frustules form part of the fossil record and accumulate in sediments, providing data for biostratigraphy and paleoenvironments.

Taxonomy and research: Species identification relies on detailed examination of frustule morphology. Molecular methods have begun to refine Diatoma relationships, but many taxa remain distinguished by morphological characters. The genus contributes to studies of freshwater diatoms and to environmental monitoring.