2.4. Species delimitation I: ABGD analysis of pairwise COI distances

Pairwise TrN distances for aligned COI haplotypes were calculated in MEGA 6.06 (Tamura et al., 2013) and analyzed by Automated Barcode Gap Discovery (ABGD; Puillandre et al., 2012) for each genus separately, using a range of priors (pmin = 0.004; pmax = 0.08), with 10 recursive steps and 20 bins. The pmax value was based on prior studies in sacoglossans in which divergent mtDNA clades were supported as CS if the minimum TrN-corrected COI distance to the sister group was 6–8% (Krug et al., 2013, 2015, 2016). A value of X = 1.5 was used as the sensitivity for gap detection, with X the minimum relative gap width required to delimit a CS; groups of sequences that differed by > 1.5 times the maximum intraspecific divergence were separated into CS. Initial ABGD analyses recovered five morphologically distinct Lobiger CS and five divergent Oxynoe CS in the Indo-West Pacific (IWP); remaining samples belonged to the O. antillarum-viridis complex, including putative O. antillarum (n = 44), O. azuropunctata-like Caribbean specimens (n = 8), IWP O. viridis (n = 30), and eastern Pacific samples (n = 10) (see Section 3). Subsequent delimitation focused on generating alternative hypotheses for complex members, as ABGD grouped IWP “O. viridis” with eastern Pacific samples but split O. azuropunctata-like samples into three CS.