Microphreatus coronae ( Hershler, 1987 ) Czaja, 2025

Czaja, Alexander, Cardoza-Martínez, Gabriel Fernando, Becerra-López, Jorge Luis, Estrada-Rodríguez, José Luis, Alonzo-Rojo, Fernando, Ávila-Rodríguez, Verónica & Valenzuela-García, Ana Alejandra, 2025, World’s smallest freshwater snail? A new genus and species of subterranean snail (Gastropoda, Cochliopidae) with extremely tiny shell from Los Chorros, Coahuila, northern Mexico, Zootaxa 5660 (3), pp. 413-425 : 422

Microphreatus coronae ( Hershler, 1987) Czaja comb. nov.

Phreatodrobia coronae Hershler 1987, pp. 133–139 .

Phreatodrobia coronae Alvear et al., 2020 , pp. 7, fig. 6.

Balconorbis coronae Perez et al., 2025 . pp 140–141.

Description. See Hershler & Longley, 1987, pp. 133–134 and Perez et al., 2025 pp. 140–141.

Distribution. Endemic to springs of Val Verde County, Texas, United States.

Remarks. Phreatodrobia coronae was originally assigned to Phreatodrobia due to the similar shell outline of some species of this subterranean genus ( Hershler & Longley, 1987; p. 137). Recently, this species was transferred to the genus Balconorbis based on mitochondrial and nuclear data by Perez et al. (2025). However, according to the authors, the average divergence in COI between Balconorbis uvaldensis and P. coronae was 18.5%, slightly above the divergence among genera in related subterranean groups ( Perez et al., 2025, p. 140). Although Phreatodrobia coronae was reassigned to Balconorbis , the authors explicitly mention that this species does not fit “ perfectly ” in this genus and may need to be placed into a new genus. Our comparison shows that even according to morphological characteristics of the shell wall structure this species can be classified in neither the genus Balconorbis nor in Phreatodrobia and is consequently placed here in a new genus. The scanning electron microscope images of the proto- and teleoconch microsculpture of P. coronae shells from the original description by Hershler & Longley (1987, p. 135–136) shows similarities down to the smallest detail with shells of M. saltillensis sp. nov. described above ( Figs. 3G–I, 4A–D, 5A–D). These structural similarities indicate that both forms ( coronae and saltillensis ) belong to a same group or lineage, independent from Balconorbis and Phreatodrobia . We reassigned the material from Texas to Microphreatus as a second species of this genus.