A C and a Roman numeral is the core of it, but the databases in use carry
several more forms: a bare C for unstaged copepodites, adult, total, a
combination spanning two stages (CV_VI, CI_IV), and combinations written
without the C at all (ctyp_IV_VI). All are suffixes on a taxon name, and a
rule recognising only the first splits one taxon into several species -
cfin_CV_VI read as an animal called "cfin_CV_VI" rather than as some of
cfin.
Details
Matched without regard to case, because the databases disagree: the raw export
is upper case throughout, while original/create_database.R writes a lower
case taxon with an upper case stage.
Examples
grepl(stage_suffix_pattern(), "cfin_CV", ignore.case = TRUE)
#> [1] TRUE