Recently discovered amber-preserved fossil Cicadellidae exhibit combinations of morphological traits not observed in the modern fauna and have the potential to shed new light on the evolution of this highly diverse family. To place the fossils explicitly within a phylogenetic context, representatives of five extinct genera from Cretaceous Myanmar amber, and one from Eocene Baltic amber were incorporated into a matrix comprising 229 discrete morphological characters and representatives of all modern subfamilies. Phylogenetic analyses yielded well resolved and largely congruent estimates that support the monophyly of most previously recognized cicadellid subfamilies and indicate that the treehoppers are derived from a lineage of Cicadellidae. Instability in the morphology-based phylogenies is mainly confined to deep internal splits that received low branch support in one or more analyses and also were not consistently resolved by recent phylogenomic analyses. Placement of fossil taxa is mostly stable across analyses. Three new Cretaceous leafhopper genera, Burmotettix gen. nov., Kachinella gen nov., and Viraktamathus gen. nov., consistently form a monophyletic group distinct from extant leafhopper subfamilies and are placed in Burmotettiginae subfam. nov. Extinct Cretaceous fossils previously placed in Ledrinae and Signoretiinae are recovered as sister to modern representatives of these groups. Eomegophthalmus Dietrich and Gonçalves from Baltic amber consistently groups with a lineage comprising treehoppers, Megophthalminae, Ulopinae, and Eurymelinae but its position is unstable. Overall, the morphology-based phylogenetic estimates agree with recent phylogenies based on molecular data alone suggesting that morphological traits recently used to diagnose subfamilies are generally informative of phylogenetic relationships within this group.
Molecular phylogenetics of swimming crabs (Portunoidea Rafinesque, 1815) supports a revised family-level classification and suggests a single derived origin of symbiotic taxa
Portunoidea is a diverse lineage of ecologically and economically important marine crabs comprising 8 families and 14 subfamilies. Closely related portunid subfamilies Caphyrinae and Thalamitinae constitute some of this group’s greatest morphological and taxonomic diversity, and are the only known lineages to include symbiotic taxa. Emergence of symbiosis in decapods remains poorly studied and portunoid crabs provide an interesting, but often overlooked example. Yet the paucity of molecular phylogenetic data available for Portunoidea makes it challenging to investigate the evolution and systematics of the group. Phylogenetic analyses, though limited, suggest that many putative portunoid taxa are para- or polyphyletic. Here I augment existing molecular data—significantly increasing taxon sampling of Caphyrinae, Thalamitinae, and several disparate portunoid lineages—to investigate the phylogenetic origin of symbiosis within Portunoidea and reevaluate higher- and lower-level portunoid classifications. Phylogenetic analyses were carried out on sequences of H3, 28S rRNA, 16S rRNA, and CO1 for up to 168 portunoid taxa; this included, for the first time, molecular data from the genera Atoportunus , Brusinia , Caphyra , Coelocarcinus , Gonioinfradens , Raymanninus , and Thalamonyx . Results support the placement of all symbiotic taxa ( Caphyra , Lissocarcinus , and two Thalamita ) in a single clade derived within the thalamitine genus Thalamita . Caphyrina Paulson, 1875, nom. trans. is recognized here as a subtribe within the subfamily Thalamitinae. Results also support the following taxonomic actions: Cronius is reclassified as a thalamitine genus; Thalamonyx is reestablished as a valid genus; Goniosupradens is raised to the generic rank; and three new genera ( Zygita gen. nov., Thranita gen. nov., and Trierarchus gen. nov.) are described to accommodate some Thalamita s.l. taxa rendered paraphyletic by Caphyrina. A new diagnosis of Thalamitinae is provided. Results also support a more conservative classification of Portunoidea comprising three instead of eight extant families: Geryonidae (Geryonidae + Ovalipidae; new diagnosis provided), Carcinidae (Carcinidae + Pirimelidae + Polybiidae + Thiidae + Coelocarcinus ; new diagnosis provided) and Portunidae. Finally, 16s rRNA data suggests family Brusiniidae might not be a portunoid lineage.
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- Award ID(s):
- 1406368
- NSF-PAR ID:
- 10057078
- Date Published:
- Journal Name:
- PeerJ
- Volume:
- 6
- ISSN:
- 2167-8359
- Page Range / eLocation ID:
- e4260
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Xiphosurans are aquatic chelicerates with a fossil record extending into the Early Ordovician and known from a total of 88 described species, four of which are extant. Known for their apparent morphological conservatism, for which they have gained notoriety as supposed ‘living fossils’, recent analyses have demonstrated xiphosurans to have an ecologically diverse evolutionary history, with several groups moving into non-marine environments and developing morphologies markedly different from those of the modern species. The combination of their long evolutionary and complex ecological history along with their paradoxical patterns of morphological stasis in some clades and experimentation among others has resulted in Xiphosura being of particular interest for macroevolutionary study. Phylogenetic analyses have shown the current taxonomic framework for Xiphosura—set out in the Treatise of Invertebrate Paleontology in 1955—to be outdated and in need of revision, with several common genera such as Paleolimulus Dunbar, 1923 and Limulitella Størmer, 1952 acting as wastebasket taxa. Here, an expanded xiphosuran phylogeny is presented, comprising 58 xiphosuran species as part of a 158 taxon chelicerate matrix coded for 259 characters. Analysing the matrix under both Bayesian inference and parsimony optimisation criteria retrieves a concordant tree topology that forms the basis of a genus-level systematic revision of xiphosuran taxonomy. The genera Euproops Meek, 1867, Belinurus König, 1820, Paleolimulus , Limulitella , and Limulus are demonstrated to be non-monophyletic and the previously synonymized genera Koenigiella Raymond, 1944 and Prestwichianella Cockerell, 1905 are shown to be valid. In addition, nine new genera ( Andersoniella gen. nov. , Macrobelinurus gen. nov. , and Parabelinurus gen. nov. in Belinurina; Norilimulus gen. nov. in Paleolimulidae; Batracholimulus gen. nov. and Boeotiaspis gen. nov. in Austrolimulidae; and Allolimulus gen. nov., Keuperlimulus gen. nov., and Volanalimulus gen. nov. in Limulidae) are erected to accommodate xiphosuran species not encompassed by existing genera. One new species, Volanalimulus madagascarensis gen. et sp. nov., is also described. Three putative xiphosuran genera— Elleria Raymond, 1944, Archeolimulus Chlupáč, 1963, and Drabovaspis Chlupáč, 1963—are determined to be non-xiphosuran arthropods and as such are removed from Xiphosura. The priority of Belinurus König, 1820 over Bellinurus Pictet, 1846 is also confirmed. This work is critical for facilitating the study of the xiphosuran fossil record and is the first step in resolving longstanding questions regarding the geographic distribution of the modern horseshoe crab species and whether they truly represent ‘living fossils’. Understanding the long evolutionary history of Xiphosura is vital for interpreting how the modern species may respond to environmental change and in guiding conservation efforts.more » « less
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- Journal Article:
- https://doi.org/10.7717/peerj.4260
