Morphological and molecular insights on Megalothorax: the largest Neelipleona genus revisited (Collembola)

Abstract

The genus Megalothorax Willem, 1900 is redefined along with a redescription of the type species M. minimus Willem, 1900 and the description of five new species (M. granulosus, sp. nov., M. nigropunctatus, sp. nov., M. perspicillum, sp. nov., M. svalbardensis, sp. nov. and M. willemi, sp. nov.). We describe and comment on broad sets of discriminating characters for Megalothorax systematics. For the first time, trichobothria are recorded for Neelipleona, probably of generic importance. The described species are provided with DNA data (COI, 16S and 28S) and included in a molecular-based phylogenetic analysis. The traditional distinction between minimus-group and incertus-group is discussed in the light of DNA and morphology components. A key to the worldwide Megalothorax species is provided.

Two new Megalothorax species of the minimus group (Collembola, Neelidae)

“…15) follow Schneider (in press), trunk chaetotaxy (Fig. 16) follows Schneider and D’Haese (2013). The four swollen chaetae of Ant.…”

“…Forty-nine specimens of Megalothorax dataset representing 14 morphologically recognized species were selected, 36 from Schneider et al 2011, Schneider and D’Haese 2013 and 13 specimens belonging to the two new species (Table 4). …”

“…Massoud and Ellis 1977), and use instead the following categories defined by Schneider (in press): (i) s-chaetae for the short swollen chaetae of the trunk; (ii) τ-chaetae for the long and thin chaetae of the trunk (shaped as trichobothria in Megalothorax ); (iii) S-chaetae for the swollen chaetae of the antenna; (iv) neosminthuroid chaetae for the special chaetae of Abd. IV sternum as defined in Richards (1968), Betsch (1980) and Schneider and D’Haese (2013). Ordinary chaetae are simply referred as chaetae.…”

“…Ordinary chaetae are simply referred as chaetae. Nomenclature of the claw follows Schneider (in press), based on Denis (1948) and Schneider and D’Haese (2013). The presence or absence of specific chaetae is described in reference of the chaetotaxic pattern of Megalothorax minimus .…”

“…n. from the French Pyrénées are described. The two new species have a set of morphological characters (including a smooth mucro) that places them among the minimus group sensu Schneider and D’Haese (2013). Megalothorax potapovi characteristics include dorsal protuberance on forehead, peculiar chaetotaxy of antenna III and strong lanceolate chaetae on body.…”