Based on the original species descriptions, a review of the genus Paramacrobiotus was conducted. We divided the genus into two subgenera, Microplacoidus subgen. nov. and Paramacrobiotus subgen. nov., based on the presence or absence of a microplacoid, characterized species within the genus based on seven different types of eggs. In a moss sample collected in Ecuador, Paramacrobiotus (Paramacrobiotus) spinosus sp. nov., was found. The new species differs from all species of the subgenus Parama crobiotus by the presence of richtersi type eggs and from other species by morphometric characters. Additionally, in the Ecuadorian material we found P. (Microplacoidus) magdalenae comb. nov., which is the first record of this species in Ecuador, we provide the full set of measurements for this species, not included in the original description. An additional new record is P. (M.) alekseevi comb. nov. found in Vietnam for the first time. After examining microscope slides from the Iharos' collection deposited in the Hungarian Natural History Museum, we prepared re-descriptions of P. (P.) csotiensis comb nov., P. (M.) submorulatus comb. nov. and P. (M.) wauensis comb. nov. Based on the morphological and morphometric characters of adults and eggs, we developed a diagnostic key to the genus Paramacrobiotus.