# Luticola edaphica sp. nov. (Diadesmidaceae, Naviculales) from the Soil of the Russian Far East (Primorsky Territory, Russia)

## TL;DR

A new species of Luticola, Luticola edaphica, was discovered in forest soils in the Russian Far East using a combination of molecular and morphological methods.

## Contribution

The discovery of Luticola edaphica and its unique reproductive traits expands our understanding of the Luticola genus.

## Key findings

- Luticola edaphica is a new species distinguished by specific morphological traits and phylogenetic data.
- The species exhibits homothallic reproduction and trans-anisogamy, a first for the genus.
- The new species was identified using an integrative taxonomic approach.

## Abstract

The naviculoid genus Luticola exhibits a high degree of morphological convergence, complicating species delimitation when based solely on traditional morphometrics. Here, we describe Luticola edaphica sp. nov., a new species isolated from the forest soils of Mount Sestra (Primorsky Territory, Russian Far East) using an integrative taxonomic approach (phylogenetic, morphological, ultrastructural, and life cycle data). Molecular phylogenetic analysis, based on the chloroplast rbcL gene, placed the new strain within the Luticola clade, showing the closest affinity to L. tenera. However, L. edaphica is distinguished from similar Luticola species by a unique combination of morphological traits (structure of the valvocopula, maximal valve length and width, position and number of striae in 10 µm, central area, and distal raphe ends). A comprehensive study of its life cycle revealed that L. edaphica is homothallic and capable of both cis- and trans-anisogamy, with the latter being reported for the genus for the first time.