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Delphacid Phylogeny


The evolutionary development and history of delphacid planthoppers
The phylogeny of the Delphacidae was historically investigated by Muir (1915, 1930), Haupt (1929), Metcalf (1943), and Wagner (1963), with a slight modification by Fennah (1979).  These studies were non-quantitative, except Wagner, but provided baseline hypotheses for delphacid phylogeny.  Muir divided the Delphacidae into 2 subfamilies (Asiracinae and Delphacinae), the latter of which had three tribes (Alohini, Tropidocephalini, Delphacini).  Metcalf (1943) essentially followed Muir, but because of a nomenclatural problem involving the type genus Delphax (resolved in ICZN, 1961, opinion 602), he used Araeopus as the type genus, therefore substituting “Araeopidae”, “Araeopinae” and “Araeopini” for names with the stem “Delphax”.  Haupt (1929) explicitly treated only elements of the Palearctic fauna, but suggested 4 subfamilies (Asiracinae, Tropidocephalinae, Megamelinae, and Delphacinae).  Wagner (1963) provided a more rigorous analysis of delphacid phylogeny based on the Palearctic fauna, but his analysis was based on a theoretically doubtful concept.  Wagner (1963) recognized 9 subfamilies and presented these in a phylogenetic tree (see figure).  Wagner’s subfamilies in sequence from basal to derived are Asiracinae, Kelisiinae, Jassidaeinae, Stirominae, Achorotilinae, Delphacinae, Chlorioinae, Stenocraninae, and Megamelinae.  Vilbaste (1968) recognized the subfamily Saccharosydninae (subsequently treated as a tribe of Delphacinae). Finally, Fennah (1979) divided the Asiracinae into two tribes (Asiracini and Ugyopini).  These classifications are summarized in Asche (1985).

The first cladistic treatment of the higher taxonomy of the Delphacidae was that of Asche (1985, 1990).   Previous studies were unsatisfactory because their “… results were either only phenetical groupings for diagnostic purposes…[or] an artificial system based on so-called ‘anagenic trends’ … leading to perfect confusion” (Asche, 1985: 366).  Asche (1985, 1990) divided the family Delphacidae into 7 clades (see figure), including the polyphyletic Asiracinae (comprised by Asiracini and Ugyopini) and five monophyletic subfamilies (Vizcayinae, Kelisiinae, Stenocraninae, Plesiodelphacinae, and Delphacinae).  The Delphacinae is a particularly large subfamily, including over 80% of all delphacid species, and is comprised of three tribes, the Saccharosydnini (3 genera, 9 species), the Tropidocephalini (31 genera, ~172 species), and the Delphacini (~296 genera and 1,600 species); for review, see Wilson et al. 1994).  Asche’s (1985) Delphacini includes the Achorotilinae, Alohini, Chlorioinae, Megamelinae, and Stirominae of previous authors because they have not “…proved to be monophyletic by the presence of at least one common derived homologous (= synapomorphic) character” (Asche 1985: 366).  At present, the relationships among the genera of the Delphacini remain unresolved.  

Since Asche (1985, 1990), two other workers have suggested modifications to the higher taxonomy of the Delphacidae.  Emeljanov (1996) investigated immature forms of Delphacidae.  He proposed that the asiracine tribes (viz. Ugyopini and Asiracini) be raised to subfamily status, and proposed a series of new tribes (see figure).  He proposed, in the subfamily Asiracinae, the new tribes Idiosystanini, Platysystatini, Tetrasteirini, and Asiracini; and in the Ugyopinae the tribes Eodelphacini, Neopunanini, and Ugyopini.  All remaining delphacid taxa were treated as tribes of Delphacinae (viz. Vizcayini, Kelisini, Stenocranini, Plesiodelphacini, Delphacini, Tropidocephalini, Saccharosydnini) with the same branching pattern as suggested by Asche (1985, 1990).   More recently, Hamilton (2006) treated Kelisiini as a subtribe of Stenocranini, and the Saccharosydnini (Delphacinae) as a subtribe of Tropidocephalini, but otherwise followed Emeljanov (1996). 

In addition to these studies, Yang and colleagues (1987) used cladistic and phenetic algorithms to investigate the relationships of Ugyops and 9 genera within the Tropidocephalini from Taiwan, providing some preliminary information regarding the relationships among these taxa.  Also Dijkstra and colleagues (2003, 2006) investigated the utility of molecular data for examining the phylogeny of the Delphacidae among a small group of taxa.  Dijkstra and colleagues (2003) concluded that the cytochrome c oxidase I (COI) gene provided signal at the subfamily level, but they suggested that the third codon was saturated among the Delphacini, partly because they were unable to resolve relationships among genera in this tribe.  Dijkstra and colleagues (2006) investigated two mitochondrial ribosomal genes, 16S and 12S, finding that 12S appears to provide better signal than COI for resolving relationships among the genera of Delphacini, but apparently not among species within genera, whereas 16S appears to provide phylogenetic signal among species within a genus.  Dijkstra and colleagues (2006) also discuss apparent differences in substitution rates between primitive and advanced delphacids, and shifts in base compositions (from T to A), hinting at possible future difficulties in resolving phylogenetic relationships.   Dijkstra and colleagues (2003, 2006) results consistently suggested a sister group relationship between the Kelisiinae and Stenocraninae.

Urban and colleagues (2010) produced a hypothesis for the phylogeny of the higher taxa, based on four genes (18s, 28s, wingless and COI) and morphology using 109 taxa, representing all subfamilies.  The higher phylogeny is similar to that from morphological studies except that the Plesiodelphacinae vary in their position depending on the analyses and the Asiracinae do not group as expected.  The Kelisiinae + Stenocraninae did group in some analyses, but this result was statistically equivocal. A jpg of the resultant tree of their Bayesian analysis is here and below.