Gray-necked Wood-Rail (Aramides cajaneus) has been split - birds from Mexico to northern and western Costa Rica are now Russet-naped Wood-Rail (A. albiventris), while birds from the central Pacific slope of Costa Rica through South America are now Gray-cowled Wood-Rail (A. cajaneus). The two species differ in plumage - Russet-naped has a rusty-brown nape (hence the name), which Gray-cowled lacks - and they also appear to differ markedly in vocalizations. (Be careful updating records from Costa Rica - the precise limits of the ranges of the two species are incompletely known, and it's thus unclear whether they come into contact; pay careful attention to nape color [and vocalizations, if you have recordings].)

From Clements:

In accord with AOU-NACC (Chesser et al. 2016), Gray-necked Wood-Rail Aramides cajaneus is split into two species: Russet-naped Wood-Rail Aramides albiventris, and Gray-cowled Wood-Rail Aramides cajaneus. This action is based on Marcones and Silveira (2015), who documented significant vocal differences, and less obvious but still consistent plumage differences, between the two species; they also pointed out that these two species appear to be parapatric, replacing one another rather abruptly. Following Marcones and Silveira (2015) Russet-naped Wood-Rail is considered to be monotypic; subspecies mexicanus, vanrossemi, pacificus, and plumbeiceps all are considered to by junior synonyms of albiventris, and are deleted. Revise the range description of albiventris from “Yucatán Peninsula, Cozumel I., Belize and adj. n Guatemala” to “Mexico (north to southern Oaxaca and southern Tamaulipas) south on both slopes to Nicaragua and northeastern Costa Rica.” Again following Marcones and Silveira (2015), subspecies latens and morrisoni are considered to be junior synoynms of nominate cajaneus, and are deleted. Revise the range description of cajaneus from “Costa Rica to n Argentina, Uruguay, Brazil and the Guianas” to “Costa Rica south to northwestern Colombia (including islands off of Panama) and, east of the Andes, to the Guianas and northeastern Brazil south to northern Argentina and Uruguay.”

References:

Chesser, R.T., K.J. Burns, C. Cicero, J.L. Dunn, A.W. Kratter, I.J. Lovette, P.C. Rasmussen, J.V. Remsen, Jr., J.D. Rising, D.F. Stotz, and K. Winker. 2016. Fifty-seventh supplement to the American Ornithologists’ Union Check-list of North American birds. Auk 133: 544-560.

Marcondes, R.S., and L.F. Silveira. 2015. A taxonomic review of Aramides cajaneus (Aves, Gruiformes, Rallidae) with notes on morphological variation in other species of the genus. ZooKeys 500: 111-140.