Richtersiidae from Guidetti et al. 2016: “Double claws Y-shaped, with the two branches forming an evident common tract of variable length. Large teeth on all lunules. Buccal tube with ventral lamina and a cuticular thick on the anterior, dorsal wall of the buccal tube (which can form a large apophysis). Absence of transverse crests in the buccal armature. Two macroplacoids in the pharynx. Cuticular pores (at least in a phase of the life cycle). Eggs laid freely with cuticular processes on their surface.”
Richtersiidae from Lisi et al. 2020: “Presence of cuticular pores at least in some life stages. Buccal tube with ventral lamina provided with an additional anterior ventral thickening which can form a large apophysis in some genera; a cuticular thickening on the anterior, dorsal wall of the buccal tube sometimes developed into a dorsal apophysis. Two macroplacoids in the pharynx. Symmetric double claws Y-shaped, with stalk system and the two branches forming an evident common tract of variable length. Large teeth on all lunules. Eggs laid freely with cuticular processes on their surface.”
Richtersiusidae from Guidetti et al. 2021: “Double claws Y-shaped, with the two branches forming an evident common tract of variable length. Large teeth on all lunules. Buccal tube with ventral lamina and a cuticular thickness on the anterior portion of the dorsal wall of the buccal tube (which can form a large apophysis). Two macroplacoids in the pharynx. Cuticular pores (at least in one phase of the life cycle). Eggs laid freely with processes on their surface.”
Richtersiusidae from Stec 2023: “Double claws Y-shaped, with the two branches forming an evident common tract of a variable length with system of internal septa. In majority of taxa included within the family, teeth present in lunulae on all legs. Buccal tube with ventral lamina exhibiting ventral thickening in its anterior portion (sometimes hardly visible under light microcope) and a cuticular thick on the anterior, dorsal wall of the buccal tube (which can form a large apophysis). Absence of transverse crests in the buccal armature. Two macroplacoids in the pharynx. Microplacoid absent. Cuticular pores (at least in a phase of the life cycle). Eggs laid freely with conical (usually spiky) processes and without areolation on their surface. Body and leg granulation absent in all currently recognized species.”
Richtersiusidae from Massa et al. 2024: “Double claws Y-shaped, with the two branches forming an evident common tract of a variable length with system of internal septa. Teeth present or absent on lunulae I-III and always present on lunulae IV. Buccal tube with ventral lamina exhibiting ventral thickening in its anterior portion
(sometimes hardly visible under light microscope) and a cuticular thickening on the anterior, dorsal wall of the buccal tube (which can form a large apophysis). Transverse crests in the buccal armature absent. Two macroplacoids in the pharynx. Microplacoid present or absent (in most taxa). Cuticular pores (at least in a phase of the life cycle). Eggs laid freely with conical (usually spiky) processes and without areolation on their surface.
Body and leg granulation absent in all currently recognized species.”
Citations:
Guidetti, R., Rebecchi, L., Bertolani, R., Jönsson, K.I., Kristensen, R.M. & Cesari, M. (2016) Morphological and molecular analyses on Richtersius (Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea. Zoological Journal of the Linnean Society, 178, 834–845.
Guidetti, R., Schill, R.O., Giovannini, I., Massa, E., Goldoni, S.E., Ebel, Ch., Förschler, M.I., Rebecchi, L. & Cesari, M. (2021) When DNA sequence data and morphological results fit together: Phylogenetic position of Crenubiotus within Macrobiotoidea (Eutardigrada) with description of Crenubiotus ruhesteini sp. nov. Journal of Zoological Systematics and Evolutionary Research. https://doi.org/10.1111/jzs.12449, 59 (3), 576–587.
Lisi, O., Londoño, R. & Quiroga, S. (2020) Description of a new genus and species (Eutardigrada: Richtersiidae) from Colombia, with comments on the family Richtersiidae. Zootaxa, 4822 (4): 531–550.
Massa, E., Vecchi, M., Calhim, S. & Choong, H. (2024) First records of limnoterrestrial tardigrades (Tardigrada) from Haida Gwaii, British Columbia, Canada. The European Zoological Journal, 91, 1–20. https://doi.org/10.1080/24750263.2023.2288824
Stec, D. (2023) Integrative taxonomy helps to revise systematics and questions the purported cosmopolitan nature of the type species within the genus Diaforobiotus (Eutardigrada: Richtersiusidae). Organisms Diversity & Evolution, 23 (2), 309–328. https://doi.org/10.1007/s13127-022-00592-6
