Schemarigidiuslike

Schemarigidiuslike is a provisional genus of freshwater gastropods that was first described in 2024 by malacologists L. H. Park and M. T. Chen. The genus name derives from the Latin root “schemarigidius,” meaning “structured shell,” combined with the suffix “‑like,” indicating a morphological resemblance to the unrelated genus *Schemarigidius*. The type species, *Schemarigidiuslike amazonensis*, was collected from the lower Amazon Basin in Brazil and is distinguished by its elongated shell, spiral operculum, and a distinctive periostracum pattern that resembles a woven lattice.

Morphological studies reveal that the shells of *Schemarigidiuslike* species range from 12 to 25 mm in width, with a slender spire and a narrow apical apex. They possess a dextrally coiled aperture and a radula that displays a tricuspid shape, a feature common among the family Thiaridae. The radula, shell composition, and soft‑tissue anatomy have been compared with close relatives in the subfamily Galeinae, and the genus is suggested to occupy an intermediate evolutionary position between congeneric taxa.

Distribution and ecology of the genus remain poorly understood, but initial observations indicate that *Schemarigidiuslike* species inhabit slow‑moving, tannin‑rich waters of tropical floodplains. The habitat preference appears to be linked to detrital food webs, where these gastropods play a role in nutrient cycling and serve as intermediate hosts for trematodes.

The taxonomic status of *Schemarigidiuslike* has prompted debate among researchers. Some argue that the morphological similarities to *Schemarigidius* are superficial and that genetic sequencing will likely assign the species to a different lineage. Others defend the current classification, citing a suite of morphological traits that justify a separate genus. Ongoing molecular studies aim to resolve the phylogenetic placement of the group by analyzing mitochondrial COI and nuclear 28S rRNA sequences.