Taxonomy matters: Three tardigrade stories from our lab

Taxonomic and faunistic studies play a critical role in biodiversity science. Without accurate species descriptions and distribution data, the ecological, evolutionary, and conservation research rests on shaky ground. Tardigrades are a perfect example: although they’re often used as model organisms in stress physiology or astrobiology, basic knowledge about their species diversity and biogeography remains surprisingly incomplete. Recently, our team has helped fill some of these gaps through three complementary publications, each with a story to tell.

1. The curious case of a microscopic discovery on Facebook

Imagine scrolling through Facebook and stumbling upon a photo, not of someone’s vacation, but of tiny and chunky creatures swimming in a puddle of water. That's exactly how the story of Dactylobiotus taiwanensis began. A Taiwanese hobbyist posted these photos, which caught our eye, and this chance encounter led to the discovery of a new species of tardigrade. These water bears, found in a lotus pond, had eggs covered in short, cone-shaped spikes, each surrounded by a perfect circle of tiny pores, something never seen before in this group. While describing it, we also re-evaluated two previously known Dactylobiotus species and questioned their validity, since key identifying features, like egg morphology, were never described.

Figure 1. Dactylobiotus taiwanensis — an adult animal imaged using phase contrast light microscopy, with egg morphology shown under scanning electron microscopy (Photos by D. Stec and D. Camarda).

2. The space-traveling tardigrade with the wrong name

The genus Richtersius is full of large, yellow tardigrades that are charismatic and famously able to survive complete dehydration, radiation, and even spaceflight. And for a long time, they were all known by a single name: R. coronifer. In this study, we described two new species, R. nicolai from Italy and R. ingemari from Sweden, based on their appearance and DNA. Although they resemble R. coronifer, genetic analysis revealed they’re distinct species.

Here’s the twist: the Swedish population of R. ingemari has been used in nearly 30 scientific studies, including a space mission, under the incorrect name R. coronifer. This shows that taxonomy isn’t just about naming things; it’s about ensuring the reliability of scientific research across disciplines.

Figure 2. A yellowish hatchling of an unknown Richtersius species from Italy, imaged using light microscopy (Photo by D. Camarda).

3. The predator next door: New records of Milnesium in Poland

Tardigrades in the genus Milnesium are known for their clawed legs and powerful mouthparts, as they prey on other micro-animals. In this study, we recorded three species of Milnesium in Poland for the first time: M. guanyinensis, M. berladnicorum, and M. inceptum. One of these, M. guanyinensis, is especially intriguing, as it’s the first time this species has ever been found in the Palearctic region (which includes most of Europe and northern Asia), raising questions about whether it arrived there naturally or with human help. Using a combination of microscope work and DNA barcoding, we boosted the known number of Milnesium species in Poland from four to seven. This also brings the country’s total known tardigrade species count to 118.

A video of a female Milnesium that lays eggs inside her old exoskeleton, then struggles to crawl out. Video credit: D. Camarda.

These three stories remind us that even the most high-tech science rests on a basic foundation: knowing who’s who. In an era of accelerating environmental change and high-throughput data, the slow, careful work of naming, mapping, and revising species remains as essential as ever. Whether it’s a new species discovered via Facebook, a lab strain that flew to space under the wrong name, or predators hiding in plain sight, taxonomy isn’t a dusty old practice. It’s the infrastructure of science. And like any infrastructure, it has to be solid.