ECHINISCOIDIDAE KRISTENSEN &, 1980

Møbjerg, Nadja, Jørgensen, Aslak & Kristensen, Reinhardt M., 2020, Ongoing revision of Echiniscoididae (Heterotardigrada: Echiniscoidea), with the description of a new interstitial species and genus with unique anal structures, Zoological Journal of the Linnean Society 188 (3), pp. 663-680 : 668

FAMILY ECHINISCOIDIDAE KRISTENSEN & HALLAS, 1980

Diagnosis (amended): Unplated, marine Echiniscoidea . Adults with supernumerary claws (six to 13) on each leg. Secondary clava (papilla cephalica) domeshapedor almostflat (indistinct). Median cephalic cirrus always absent. Other cephalic appendages and leg appendages small (reduced). Cirri Aand E similar in both structure and length. The fourth leg sensory structure is papillar, as is the primary clava. Stylet sheath present; stylet supports always absent. Seminal receptacles lacking. External fertilization of the smooth eggs. Anal system consists of two lateral lobes and a terminal lobe. The anal opening is located in front of the terminal lobe.

Type genus: Echiniscoides Plate, 1889 .

Discussion: The family Echiniscoididae consists of two subfamilies: Echiniscoidinae and Isoechiniscoidinae . The presence of supernumerary (six to 13) claws in adults is not seen in any other heterotardigrades. Seminal receptacles are never present in Echiniscoididae , but within Echiniscoidea seminal receptacles are found in Oreella Murray, 1910 ( Binda & Kristensen, 1986; Dastych et al., 1998).