**1. Introduction**

Canada is the second largest country in the world which extends its longitude from approximately 52◦ to 141◦ W to latitude approximately 42◦ to 83◦ N. It has such a distance that spans in six time zones and has a wide variety of climates. The highest peak in Canada which is Mount Logan reaches 5959 m asl and the country's landform structure can be considered a vast basin. Additionally, people living in two-thirds of the area experience very cold winters and short, cool summers. However, the interior plains of central southern area come with very cold winters, hot summers, and relatively sparse precipitation. Nonetheless, climate with hot, humid summers and cold, snowy winters also prevails in Southern Ontario and Quebec. Except for the west coast, all of Canada has a

**Citation:** Kayastha, P.; Roszkowska, M.; Mioduchowska, M.; Gawlak, M.; Kaczmarek, Ł. Integrative Descriptions of Two New Tardigrade Species along with the New Record of *Mesobiotus skorackii* Kaczmarek et al., 2018 from Canada. *Diversity* **2021**, *13*, 394. https://doi.org/10.3390/ d13080394

Academic Editor: Michael Wink

Received: 20 July 2021 Accepted: 19 August 2021 Published: 22 August 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

winter season with average temperatures below freezing and with continuous snow cover (https://www.britannica.com/place/Canada (accessed on 18 June 2021).

Tardigrada, also commonly known as water bears, inhabit in terrestrial and aquatic (freshwater and marine) environments. They can be found on aquatic plants and/or in lichens, leaf litter, mosses, soil, sediments [1–3]. To date, more than ca. 1300 species of tardigrades have been described throughout the world [4–7]. The genus *Bryodelphax* [8] is unique amongst Echiniscidae with some peculiar apomorphies like presence of 10 peribuccal papulae and plesiomorphies like ancestral type of the buccal apparatus, which makes *Bryodelphax* a good example of mosaic evolution in tardigrades [9,10]. Moreover, it is characterized by the presence of median plates 1 and 2 divided, median plate 3 not divided, and absence of notches on terminal plate. Up to now, 26 species were attributed to this genus [7]. The genus *Macrobiotus* [11] is one of the most species-rich and widespread genus in the phylum being also, the first formally described tardigrade genus. It is characterized by the presence of a rigid buccal tube with a straight ventral lamina lacking a ventral hook, 10 peribuccal lamellae, pharynx with two macroplacoids and microplacoid, symmetrical diploclaws and freely laid ornamented eggs [12]. Up to now, 118 species were attributed to this genus [7].

Tardigrade fauna of Canada is rather poorly known and up to now only 121 species have been reported from this region [13,14]. In this study, we applied integrative taxonomy for description of two new species from Canada belonging to the genus *Bryodelphax* and the *Macrobiotus hufelandi* complex. Moreover, we enriched this paper in additional molecular and morphometric data of the Canadian record of *Mesobiotus skorackii* Kaczmarek, Zawierucha, Buda, Stec, Gawlak, Michalczyk and Roszkowska [15], as the original description of this species was prepared based solely on the morphology and morphometry.
