ZooKeys 649: Making the Most of Your Host The Metrosideros-Feeding Psyllids (Hemiptera, Psylloidea) of the Hawaiian Islands

About this book

A remarkable radiation of jumping plant lice, or psyllids, in the Hawaiian Islands reveals complex patterns of variation indicative of dynamic evolutionary processes. These small, herbivorous insects have diversified on a single, highly variable host plant by partitioning the host plant phenospace. They appear to have done this by partitioning the host ecologically, making different gall types on different plant parts, and by fine scale temporal and spatial partitioning. The genus Pariaconus is redescribed and 25 new species are described, taking the total number of species in the radiation to 36 named taxa with more species likely still to be discovered. The host plant, Metrosideros polymorpha, is one of the most widespread and iconic species in the native Hawaiian flora, know locally as ‘ohia’ or ‘ohia lehua’. Yet, despite being both widespread and abundant, this plant species is known to be vulnerable to a variety of ecologically devastating proce sses, e.g. a fungal pathogen causing "rapid ohia death", which could precipitate local extinction in many of the rarer Pariaconus species. Pariaconus provides a superb model system for understanding evolution in herbivorous insects. The 36 species are distributed throughout the Hawaiian Islands and provide many natural replicates for testing hypotheses of plant-insect interaction, host manipulation during galling, parallel evolution, and sympatric speciation.

Contents

Introduction   4
Materials, methods and terminology   8
      Sampling   8
      Molecular analysis   37
      Morphological analysis   37
Results   46
      Taxonomic placement of Pariaconus and outgroup analysis   46
      Ancestral character state reconstruction: a galling or non-galling origin?   48
      Divergence within Pariaconus   48
      Divergence within the bicoloratus group   51
      Divergence within the minutus group   51
      Divergence within the kamua group   51
      Divergence within the ohialoha group   52
Discussion   54
      Origins of Pariaconus and other Myrtaceae-feeders   54
      Does Pariaconus diversification parallel Metrosideros?   55
      Intra-island divergence in Pariaconus   56
      Parallel diversification in Pariaconus   58
Conclusions   60
Taxonomic treatment   60
      Triozidae Löw, 1879   60
            Pariaconus Enderlein, 1926   60
            bicoloratus species group   66
      Adult key to Pariaconus species groups   64
      Adult key to Pariaconus species in the bicoloratus and minutus species groups (found on Oahu, Molokai, Maui, Hawaii)   64
            Pariaconus nigricapitus (Crawford, 1918)   66
            Pariaconus hina Percy, sp. n.   69
            Pariaconus wyvernus Percy, sp. n.   72
            Pariaconus nigrilineatus Percy, sp. n.   74
            Pariaconus kapo Percy, sp. n.   76
            Pariaconus proboscideus Percy, sp. n.   77
            Pariaconus poliahu Percy, sp. n.   79
            Pariaconus lona Percy, sp. n.   81
            Pariaconus liliha Percy, sp. n.   82
            Pariaconus gracilis (Crawford, 1918)   84
            Pariaconus dorsostriatus Percy, sp. n.   87
            Pariaconus namaka Percy, sp. n.   89
      minutus species group   91
            Pariaconus minutus (Crawford, 1918)   91
            Pariaconus gibbosus Percy, sp. n.   94
      kamua species group   95
      Adult key to Pariaconus species found on Kauai – kamua species group   96
            Pariaconus iolani (Kirkaldy, 1902), comb. n.   97
            Pariaconus hiiaka Percy, sp. n.   100
            Pariaconus melanoneurus Percy, sp. n.   102
            Pariaconus grandis Percy, sp. n.   104
            Pariaconus caulicalix Percy, sp. n.   106
            Pariaconus crassiorcalix Percy, sp. n.   108
            Pariaconus lehua (Crawford, 1925), comb. n.   110
            Pariaconus elegans Percy, sp. n.   112
            Pariaconus gagneae Percy, sp. n.   113
            Pariaconus haumea Percy, sp. n.   114
      ohialoha species group   116
      Adult key to Pariaconus species in the ohialoha species group found on Oahu   116
      Adult key to Pariaconus species in the ohialoha species group found on Molokai   116
      Adult key to Pariaconus species in the ohialoha species group found on Maui   117
      Adult key to Pariaconus species in the ohialoha species group found on Hawaii   117
            Pariaconus oahuensis Percy, sp. n.   117
            Pariaconus ohiacola (Crawford, 1918), comb. n.   122
            Pariaconus lanaiensis (Crawford, 1918), comb. n.   125
            Pariaconus pullatus (Crawford, 1918), comb. n.   126
            Pariaconus molokaiensis (Crawford, 1927), comb. n.   126
            Pariaconus hualani Percy, sp. n.   128
            Pariaconus mauiensis Percy, sp. n.   130
            Pariaconus kupua Percy, sp. n.   132
            Pariaconus montgomeri Percy, sp. n.   134
            Pariaconus hawaiiensis (Crawford, 1918), comb. n.   136
            Pariaconus pele Percy, sp. n.   138
            Pariaconus pyramidalis Percy, sp. n.   141
Acknowledgements   154
References   154
Supplementary material 1   163

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