Zoological Studies

Vol. 58, 2019

(update: 2019.09.18)

What If Multiple Claw Configurations Are Present in The Sample? A Case Study with Description of Milnesium pseudotardigradum sp. nov. (Tardigrada) with Unique Developmental Variability

Bartłomiej Surmacz, Witold Morek*, and Łukasz Michalczyk


Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland. *Correspondence: E-mail: wmorek@op.pl. E-mail: bartek9865@gmail.com (Surmacz); LM@tardigrada.net (Michalczyk)

Received 14 June 2019 / Accepted 3 September 2019
Communicated by Benny K.K. Chan

The tardigrade fauna of Iceland was a subject of studies since the middle XX century. So far, only a single species of the genus Milnesium was reported, M. tardigradum, which at the time was assumed to have a cosmopolitan distribution. However, the record comes from before the redescription of M. tardigradum, thus the validity of the Icelandic record is questionable. Some species of Milnesium are characterised by developmental variability, which is most pronounced in the morphology of secondary branches of claws, exhibited by shift in the number of spurs. In this contribution, we present a case study where multiple claw configurations (CC) were found in a single lichen sample from Iceland, indicating the presence of more than one species and/or multiple phenotypes representing different ontogenetic stages. To elucidate this puzzle, we utilised a range of integrative tools, including detailed morphology, morphometry, barcoding and development tracking. We present the workflow, which enabled us to collect the data for each species/morphotype. As a result, we revealed the presence of three species, two characterised by an ontogenetic CC change and one with a stable CC. Finally, we provide a description of a new species, M. pseudotardigradum, which is extremely similar to M. tardigradum, but it can be phenotypically differentiated by a unique, double CC change pattern.

Key words: Cryptic species, Developmental variability, Ontogeny, Pseudocrypsis, Species distribution.

Citation: Surmacz B, Morek W, Michalczyk L. 2019. What if multiple claw configurations are present in the sample? A case study with description of Milnesium pseudotardigradum sp. nov. (Tardigrada) with unique developmental variability. Zool Stud 58:0ff. doi:-.