Dilychnia, Motschulsky, 1853

WHAT IS DILYCHNIA View in CoL ?

The tribe Photinini and subtribe Lucidotina as traditionally defined (i.e. based on McDermott, 1966) have been found to be non-monophyletic, in part because the diagnostic features of these groups were deemed homoplastic ( Jeng, 2008; Martin et al., 2017). In this context, genera of Lucidotina , including Dilychnia , are difficult to discriminate from other genera within the subtribe, because their generic definitions largely overlap, resulting in a collection of nomenclatural changes over the years (see above). The present study is a step towards resolving the taxonomy of Dilychnia , based on MP and BI methods, and provides the first analysis of any Neotropical firefly taxon.

Although the phylogenetic relationships with other lampyrid genera remain largely unexplored, it was recently proposed that Dilychnia could be closely related to Vesta , the type genus of subtribe Amydetinae : Amydetini : Vestina ( Jeng, 2008). In addition to the type species and its allies, two other species of Vesta were included in our study: V. scutellonigra and V. thoracica . These two did not group as sister species in our analysis, suggesting that similarities found between these two species might be plesiomorphic or convergent. However, it cannot be ruled out that limited taxon sampling might have influenced their placement in our phylogeny and obscured their relationship. We find that these two Vesta spp. share the similar orange–black colour pattern with Dilychnia spp. , in addition to three synapomorphies: (5) antennomere III with apex shape rounded; (64) aedeagus paramere with apical constriction; (66) and posterior margin straight. The Neotropical species V. thoracica shares more similarities with Dilychnia than V. scutellonigra from Southeast Asia, such as: elytron with acute apical third, sternum VIII with posterior angles not projected, aedeagus with phallus shorter than paramere and phallus overall straight in lateral view. In other words, it is possible that the genus Vesta is not a monophyletic group.