Recorded Live at Old Heaven Books in Shenzhen City, which has distinguished itself as quite a hotbed of improvised and other challenging music in southern China, New Species captures the duo of Lao Dan on tenor saxophone and homemade and modified flutes and Vasco Trilla on percussion. The result is mesmerizing.

Lao and Trilla have both distinguished themselves over the last few years as free improvisors of a unique ilk. Whereas some musicians convincingly settle into one musical corner or another and, in the process, make it their own, Lao and Trilla continually surprise not just with their skill but with their itinerant interests and unique approaches to their instruments. Here, Lao swings from soulful meditations to heavy metallic drones to classical Chinese bucolia, though he is at his most emotive when he wrenches his saxophone for every squeak and squeal and throaty huff it can produce — it seems sometimes doubling on two at once — and, alternately, lays into the more traditional harmonic approaches of his bamboo flutes. Trilla meanwhile indulges in the frictions and resonances of this set, establishing a directive ceremonial ambiance rather than rhythmic direction.

On New Species, the duo lays out a gamut of techniques but generally keep things introspective and spare. In that combination, they establish a sound that is vast, spacious, and dynamic. The outing is completely improvised, and, as the best improvisors do, Lao and Trilla communicate with each other with impeccable concentration. Each allows the other space to solo or just float to the foreground for a while; neither dominates, neither follows. The result is haunting. As much as anything, Trilla evokes the patter of rain, the incidental creaks of the forest, and the unsteady rustling of disturbed stones, branches, and leaves. Lao meanwhile plays the wind, which bears pangs of loneliness and struggle but also calm equanimity. Maybe this is a message for some new future species from us, their ancestors. Maybe this is the creation of a new species of music, but a small, somewhat familiar evolutionary step rather than a sudden rupture. Either way, something special clicked between these two musicians at Old Heaven Books that night, and it is fortunate that it is now available to those who were not in the room.