The “Macrobiotus hufelandi group” is characterized by species which share some distinguishing animal and egg shell characters. In general, they have two rod-shaped macroplacoids and an evident microplacoid, eye spots, pores on the cuticle, medium sized claws, egg shell with inverted goblet-like processes, and spermatozoa with corkscrew-shaped head. We had the opportunity to analyse one species, Macrobiotus glebkai Biserov, 1990, found in Eastern Ukraine, which shows characters of the group in the animals, but a peculiar egg shell morphology. We have carried out a phylogenetic analysis on the 18S nuclear gene in order to verify the systematic position of this species. This analysis has been followed by an integrated study on morphology by LM and SEM, sex ratio, karyology and DNA barcoding (mtDNA cox1). The phylogenetic tree based on 18S sequences grouped M. glebkai with M. hufelandi and other related species with inverted goblet-like processes on the egg shell. This evidences that the egg shell morphology can sometimes be more variable than that of the animals. In depth morphological analysis allowed us to define details of both animals and eggs of M. glebkai, which showed the same characters as the Russian type material (that we also investigated). We verified that the population from Eastern Ukraine was composed by females and males and that the spermatozoon morphology is in line with that found in the various species of the “Macrobiotus hufelandi group”. The oocytes contain bivalents, but their number has to be specified, as oocytes of some specimens appeared to contain more than 6 bivalents (6 bivalents is the usual pattern for amphimictic species of the “M.hufelandi group”). The DNA barcoding has evidenced the presence of three haplotypes (Kimura 2-parameter distances: 0.2-0.3%) belonging to the same haplogroup, well differentiated (more than 20%) from M. hufelandi and the other considered species of the group.
Systematic position of Macrobiotus glebkai within the “hufelandi group”, based on morphology and molecular analysis of a population from Ukraine / Kiosya, Y. e. O.; Bertolani, Roberto; Rebecchi, Lorena; Altiero, Tiziana; Cesari, Michele. - STAMPA. - 2012:(2012), pp. 59-59. (Intervento presentato al convegno 12th International Symposium on Tardigrada tenutosi a Vila Nova de Gaia, Portugal nel 23-26 July 2012).