New Subspecies of the Rodent Baiomys from Central America

The paper revisits the southern pygmy mouse, a tiny rodent whose range stretches from central Mexico down through Nicaragua. Earlier work recognized two subspecies, one dark‑toned from Chiapas and Guatemala and another gray‑brown from Honduras and western Nicaragua. Fresh specimens gathered from Guatemala, El Salvador and Nicaragua reveal patterns that do not fit those established categories, prompting a closer look.

Using material loaned from major natural history museums, the author measures skull dimensions, tooth rows, tail length and coat coloration with exacting precision. Detailed descriptions of fur hue, foot pigmentation, nasal shape and cranial sutures distinguish two previously unknown forms, each linked to a specific locality in the Río Negro valley. The new names honor the collectors and reflect the subtle yet consistent differences uncovered.

These findings sharpen our picture of how this diminutive mouse varies across Central America, suggesting a richer tapestry of regional adaptations than previously imagined. Listeners will hear how careful comparative work can reveal hidden diversity hidden in museum drawers.