Tardigrades from Iztaccihuatl Volcano (Trans-Mexican Volcanic Belt), with the Description ofMinibiotuscitlaliumsp. nov. (Eutardigrada: Macrobiotidae)

The study of tardigrade diversity in Mexico is at early stage of development, to date, 56 extant species have been reported. To identify the tardigrade fauna associated with mosses in the Iztaccihuatl volcano, we performed a systematic sampling along an altitudinal and multi-habitat gradient. A total of 57 moss samples were collected, 233 adults, 20 exuviae, and 40 free-laid tardigrade eggs were extracted from them. Five species were identified, and three putative species were determined.Diphascon mitrenseandMinibiotus sidereusrepresents new records for Mexico and North America, whileAdropion scoticumis a new record for Mexico. Additionally, one new species,Minibiotus citlaliumsp. nov. was discovered; it resembles toMin. constellatus,Min.sidereusandMin. pentannulatusby the presence of a similar distribution pattern of star-shaped pores in the dorsal cuticle arranged in 11 transverse rows, which become double in the segments of the legs I-III, and by a very large star-shaped pore (5-6 tips) on each leg of the fourth pair.Minibiotus citlaliumsp. nov. differs from otherMinibiotusspecies mainly by macroplacoid length sequence, presence of both small and large star-shaped pores on the external surface on all legs, and by egg processes with inconspicuous ornamentation.