Molecular taxonomy and phylogeny of ItalianLepidurustaxa (Branchiopoda: Notostraca)

Abstract

Notostraca taxonomy is controversial, mainly owing to the high intraspecific variability of morphological characters; other complexity factors are represented by the consistent rate of reproductive variation. We undertook the molecular analyses of Italian Lepidurus taxa through the characterization of 12S, 16S and COI mitochondrial genes in new L. apus demes and in the L. couesii populations recently discovered in Southern Italy. For L. apus, the analysis of a wider data set (both in terms of molecular markers and of analysed populations) confirms the previously suggested specific rank of differentiation between its so far recognized subspecies, the Italian L. apus lubbocki and the European L. apus apus. The Italian L. couesii samples pertain to a well-defined taxonomic entity, strictly related to Canadian L. couesii. In 12S dendrograms, this taxon strongly diverges from the other North American Lepidurus species, but the relationships among nearctic taxa are unresolved. On the other hand, a high affinity between Italian/Canadian L. couesii and the circumpolar species L. arcticus is scored and a possible descent from a common ancestor is hypothesized.

Molecular phylogeny of the Notostraca

“…It also is paraphyletic with respect to the remaining congeneric species, and despite several previous molecular studies dealing with this taxon (e.g. Mantovani et al, 2004Mantovani et al, , 2009Vanschoenwinkel et al, 2012), its level of diversification still had been underestimated, as demonstrated by the discovery of a new, highly diverged lineage within L. apus lubbocki ('L. apus lubbocki 2'), which occurs in Israel.…”

“…(see Section 1). Regarding L. apus lubbocki, Mantovani et al (2009) already concluded that it should be recognised as a separate species, but they refrained from formally reinstating its species status (see Section S.8). Indeed, further investigations including morphology are needed to clarify its taxonomy, especially since we have demonstrated that this subspecies is not even monophyletic.…”

“…Molecular studies have also resulted in the reinstatement of Triops newberryi (Packard, 1871) among American Triops and in a revision of T. cancriformis that led to the reinstatement of Triops mauritanicus Ghigi, 1921 andTriops simplex Ghigi, 1921 and to the description of four new species, Triops baeticus Korn, 2010, Triops gadensis Korn and García-de-Lomas, 2010, Triops vicentinus Korn, Machado, Cristo and Cancela da Fonseca, 2010 and Triops emeritensis Korn and Pérez-Bote, 2010 thus raising the number of valid species in the genus Triops to 11 (see Korn et al, , 2010. Several molecular phylogenetic studies have shown the need for further taxonomic revisions due to cryptic diversification, such as in T. granarius , T. australiensis (see data presented in Vanschoenwinkel et al (2012)) and the subspecies of L. apus (Mantovani et al, 2009;Vanschoenwinkel et al, 2012). The latter species has been shown to be non-monophyletic (Mantovani et al, 2009;Vanschoenwinkel et al, 2012).…”

“…Several molecular phylogenetic studies have shown the need for further taxonomic revisions due to cryptic diversification, such as in T. granarius , T. australiensis (see data presented in Vanschoenwinkel et al (2012)) and the subspecies of L. apus (Mantovani et al, 2009;Vanschoenwinkel et al, 2012). The latter species has been shown to be non-monophyletic (Mantovani et al, 2009;Vanschoenwinkel et al, 2012).…”

“…They also included no more than two DNA markers to infer phylogenies, resulting in poor resolution especially of within-genus topologies (e.g. Vanschoenwinkel et al, 2012;Mantovani et al, 2004; but see Mantovani et al, 2009;Mathers et al, 2013b, for well resolved topologies, the latter two with a combined analysis of three, and seven markers, respectively). Moreover, until recently (see Mathers et al, 2013b), it remained unclear if both extant genera, Triops and Lepidurus, were monophyletic (e.g.…”