Shell oval lenticular, with an erect apex, white, fragile and not translucent. The protoconch gives the appearance of having 2 whorls, but it only has about 1,25 the following 0,5 whorl with only spiral sculpture, probably belonging to the teleoconch. The nucleus has a diameter of 0.096 mm, and together with the first subsequent 0,5 whorl (embryonic) has very small irregular tu-bercles, with some spiral lines; the rest is sculptured with five very fine spiral threads, which later are more prominent. These threads have some irregularities. The protoconch is tilted at an angle that changes with the development of the shell, and the axis of the protoconch differs from that of the teleoconch. Teleoconch with about 2,5 whorls or a little more, not enlarging as rapidly as other species. The first part, which lacks axial sculpture and has only spiral threads, could be misidentified as a part of the protoconch; after a half whorl it is sculptured with many fine axial ribs which are slightly curved. They number about 28-32 on the first whorl and from 40 to 52 on the body whorl. These ribs are elevated, and they are broader towards the end of the body whorl. Many tiny undulating spiral striae cover the entire shell, crossing the ribs but only visible on the summits under magnification. Aperture ovoid, with the outer lip sharp, only contacting the penultimate whorl for a short distance. Open umbilicus without any keel, showing the previous whorls. Shell totally white. Dimensions: From 2.00 to 2.50 mm in diameter.

By the oblique position of its apex, Macromphalina garcesi can be differentiated from the rest of the congeneric species in the area. Furthermore, M. palmalitoris has its axial ribs curved, fewer in number and less elevated, and the development of the spire is more rapid. Other species, such as Macromphalina robertsoni have a more similar shell but different protoconch sculpture, having tubercles between the threads and beginning on the nucleus; also, the axial ribs of the teleoconch begin immediately. M. paradoxa has the protoconch erect but not tilted, with two whorls, the nucleus smooth, and with the spiral threads of the protoconch more irregular and with many interconnections between them. The other Caribbean species of this genus have very different protoconch sculpture. The species of Megalomphalus, M. lamellosus and M. troudei have the shell globose and not depressed and with a shorter protoconch. M. oxychone and M. pilsbryi are also more globose and their protoconchs are different.

The species is known from the south of Cuba and Puerto Rico, and one juvenile from Panama (FLMNH) seems to belong to this species.