Figs 4, 41, 42
Material examined. Five females on slides and 30 in alcohol, Thailand: Satun Province: Khuan Don District: Ton Din cave, 6.72636°N, 100.16249°E, altitude 115 m, 8.ix.2016, S. Jantarit and A. Nilsai leg. (collection #THA_SJ_STN15). Four in alcohol deposited in NJAU and others in PSU-NHM.
GenBank number. KY704927–KY704932.
Ecology. These animals were found in a large population along a stream bank, on stalagmites, clay, gravels and rock surfaces in a humid environment where bat guano was absent.
Remarks. Coecobrya cf. polychaeta sp. nov. is almost identical to C. polychaeta sp. nov. in morphology, including having specialised, unique characters, such as extremely long antennae, elongate lateral process of labial palp, and four sublobal hairs on maxillary outer lobe. It differs from the latter only in having mac a1 on Abd. I (Fig. 41) and smooth postlabial mic X4. Mac a3 on Abd. II (Fig. 42) is present in one specimen. The great mean genetic distance 0.231 (0.219–0.239) between two populations has exceeded the mean interspecific distances reported in Porco et al. (2014), Katz et al. (2015) and Schneider et al. (2016). Two populations are only approximately 10 km distant from each other. Following the conservative line, the population from Khuan Don District is not here considered to be a separate species because widely accepted species delimitation criteria not established across divergent collembolan groups. It is better to be conservative in assigning specimens to new species than to incorrectly recognize artificial entities (Carstens et al. 2013).