The subfamily Pachyotominae in Mexico (Collembola: Isotomidae) with description of a new Pachyotoma species.

Pachyotoma primamexicana sp. nov, from Popocatépetl, Mexico is described; it is similar to Pachyotoma alpa (Christiansen & Bellinger, 1980) and P. muskegis (Guthrier, 1903). It can be distinguished from all other the members of the genus by the small size of PAO (about half the size of closest eye) and the formula (2,3,3) of the slightly capitate tenent hairs. An identification key for Nearctic Pachyotominae and a table with diagnostic morphological characters to the Nearctic species of the genus with integument clearly granulated is given. Three new records of species from Mexico are listed: Pachyotoma crassicauda (Tullberg, 1871), Coloburella octogenaria (Mills & Schmidt, 1957) and Bonetrura boneti (Yosii, 1962). A discussion on the distribution of the subfamily Pachyotominae and some notes on the biogeography of the subfamily are provided.

Three new species and one new record of Tullbergiidae (Collembola: Onychiuroidea) from Tierra del Fuego.

Three new species, Tullbergia rapoporti sp. nov., Dinaphorura nerudai sp. nov. and Dinaphorura najtae sp. nov., and one new record, Tullbergia meridionalis Cassagnau & Rapoport, 1962 are described based on specimens from Tierra del Fuego. Tullbergia rapoporti sp. nov. is similar to T. crozetensis, but can be distinguished from it by the presence of an empodial appendage and the chaetotaxy of Abd VI. Dinaphorura nerudai sp. nov. is diagnosed by the dorsal pso formula, the seven spiniform processes on Abd VI, an elongate PAO, the absence of vesicle on Ant IV and the dorsal chaetotaxy. Dinaphorura najtae sp. nov. is characterised by the dorsal pso formula, the seven spiniform processes on Abd VI, a triangular PAO, the absence of vesicle on Ant IV and the dorsal chaetotaxy.