A NEW DIATOM (BACILLARIOPHYCEAE) SPECIES FROM A THERMAL SPRING IN AZORES ARCHIPELAGO (SAO MIGUEL ISLAND, ATLANTIC OCEAN)

Background: Due to their isolation, islands offer excellent areas for the study of distribution of benthic diatoms. On the other hand, diatoms bearing canal raphe have received less attention compared to other groups of diatoms such as Navicula, Pinnularia or Amphora. Questions: Is it possible that thermal springs on islands offer a refuge for infrequent diatom species? Studied species: Platichthys furnensis C. Delgado, V. Goncalves & S.F.P. Almeida sp. nov. Study site and dates: The species here described was collected in the epilithon of a thermal spring in Sao Miguel Island (Azores Archipelago, Portugal) in September 2015. Methods: This new taxon was compared to other diatom species of the genera Nitzschia, Tryblionella, Entomoneis and Hantzschia and to the other species of the genus Platichthys. The morphology is documented by light and scanning electron images and discussed in detail. Results: Platichthys furnensis was found in a thermal pool, a similar habitat to the one where P. krammeri type was collected in Chile in 1940. P. furnensis has many structures that are characteristic of the recently described genus Platichthys, including raised canal raphe and fibulae, compressed valve face, steep valve face and numerous open copulae. Conclusions: The description of the new taxon is interesting because it is the first species within Platichthys to be described from the Northern Hemisphere.

Automated summary

This study investigated the impact of thermal springs on islands on the distribution of benthic diatom species, analyzed the morphological characteristics of the new diatom species Platichthys furnensis, and compared it with other diatom species. This marks the first description of a Platichthys species in the Northern Hemisphere.