# Prasiolopsis wulf-kochii (Prasiolales, Trebouxiophyceae), a New Species Occurring in Hairs of the Sloth Bradypus tridactylus

## TL;DR

A new species of green alga, Prasiolopsis wulf-kochii, was discovered growing in the hair of a sloth and was identified using genetic and morphological analyses.

## Contribution

The study introduces a new species of Prasiolopsis and validates the ITS-2/CBC method for species delimitation in related algae.

## Key findings

- Strain SAG 84.81 was identified as a new species, Prasiolopsis wulf-kochii, based on morphological and genetic differences.
- ITS-2/CBC analysis confirmed species boundaries and was validated against Pseudomarvania strains.
- GenBank sequences of Trichophilus welckeri were found to form a distinct lineage within Ulotrichales.

## Abstract

The monotypic genus Prasiolopsis has been known for a long time, but is often overlooked because of difficulties in identification and the morphological variability between uniseriate filaments and cell packages forming pseudoparenchymatic thalli depending on age. We investigated a strain (SAG 84.81) originally denoted as Trichophilus welckeri, which was isolated from the hairs of the sloth Bradypus tridactylus, and compared it with other available strains of Prasiolopsis and of the sister genus Pseudomarvania. Our investigations clearly showed that this strain differed in morphology, especially of the chloroplast, from those originally described for Trichophilus. Phylogenetic analyses of the SSU and ITS rDNA sequences revealed that the strain SAG 84.81 is sister to several strains of P. ramosa within the Prasiola clade (Trebouxiophyceae). Using the ITS-2/CBC approach, we clearly demonstrated that this strain represented a new species of Prasiolopsis, which we proposed here as P. wulf-kochii. In addition, we evaluated the ITS-2/CBC approach by comparing it with the two species of Pseudomarvania. All investigated strains showed CBCs and HCBCs, which support their species delimitation. The sequencing data of Trichophilus welckeri available in GenBank were phylogenetically re-evaluated by including all representatives of the Ulotrichales (Ulvophyceae). Our analyses showed that these sequences formed their own lineage within this order.