Phylogeny of Neotropical Lepidocyrtus (Collembola : Entomobryidae): first assessment of patterns of speciation in Puerto Rico and phylogenetic relevance of some subgeneric diagnostic characters

摘要

A phylogenetic analysis of the Neotropical members of genus Lepidocyrtus was conducted to assess the pattern of speciation in Puerto Rico while testing the phylogenetic information content of two characters used to diagnose subgenera. The analysis included twenty-two species of Lepidocyrtus from the Neotropical Region for which information on the tergal chaetotaxy of the trunk was available, two species of Holarctic Lepidocyrtus, three species of Pseudosinella, two species of Metasinella used in outgroup analysis and ninety-two informative characters. The results do not support a monophyletic origin for the Puerto Rican Lepidocyrtus, suggesting the current fauna originated through repeated invasions from abroad. Three instances of endemic speciation can be inferred from the cladograms. The geographical distribution and diversity of colour forms suggest that L. caprilesi and L. paracaprilesi speciated sympatrically, whereas vicariance can explain speciation for L,. lepargus and L. maldonadoi. The mode of speciation for L. dispar and L. biphasis remains unclear because the proportion of morphological variation between these species does not fit the proportions expected under the sympatric model suggested by their geographical distribution. The results support an early conclusion regarding appendicular scale distribution as a poor indicator of phylogenetic relationships. Taxa defined using this character are likely to be polyphyletic. The results disagree with a previous study in documenting low levels of homoplasy for the dental tubercle, implying that this character contains phylogenetic information useful in defining subgenera. However, the presence or absence of a dental tubercle is not diagnostic and should be used in combination with other characters. Comparisons of levels of homoplasy in Neotropical and Hawaiian Lepidocyrtus suggest that the relative position of two setae on the second abdominal tergum may be a better subgeneric character than other characters currently in use. [References: 54]