Two collections of laelaptid mites from Mexico belong to an unnamed species of Eubrachylaelaps Ewing. This species is parasitic on the volcano mouse, Neotomodon alstoni Merriam, a member of the subfamily CRICETINAE to which belong all other hosts of the known species of Eubrachylaelaps. Through the kindness of Dr. Flavio da Fonseca I have been able to examine a series of Eubrachylaelaps rotundus Fonseca. As the original description (Fonseca, 1937, p. 1602) did not include illustrations of this species, drawings are published here for the first time (Fig. 2). The host of E. rotundus is the cricetine rodent, Zygodontomys lasiurus Lund.