Scorpion higher phylogeny and classification, taxonomic anarchy, and standards for peer review in online publishing

Abstract

Soleglad and Fet's (2003a) attempt to reconstruct the phylogeny of Recent (including extant) scorpions, the revised classification derived from it, and recent emendations, mostly published in their self-edited online journal, Euscorpius, are deficient. Separate analyses of three independent matrices (morphology, 16S rDNA, 18S rDNA) were presented. In the morphological matrix, 52 binary and 10 tristate trichobothrial characters were replaced with one character comprising six ordered states representing trichobothrial ''types''. The remaining matrix of 105 characters was further reduced to 33 ''fundamental'' characters (20% of the morphological dataset), the analysis of which appears to be the basis for the revised classification presented. The taxon sample for the morphological analysis included 14 supraspecific terminal taxa representing genera, the monophyly of only 7 (12.5%) of which has been confirmed. A composite terminal, assembled from the fragments of fossils that may not be confamilial let alone monophyletic, was created for the Palaeopisthacanthidae, employed as the primary outgroup for the analysis. Other important outgroup taxa, notably eurypterids, xiphosurans and other arachnids, were omitted entirely. The morphological characters presented contained numerous unjustifiable assumptions of character polarity and phylogenetic relationship. An approach to character coding, deliberately adopted to reduce ''homoplasy'', biased the analysis towards a preconceived result. Structurally and topographically similar features in different taxa were explicitly assigned separate (often autapomorphic) states according to presumed phylogenetic relationships among the taxa in which they were observed. Putative ''reversals'' were coded as separate characters or states. Character transformation was forced by ordering, additive coding or Sankoff optimization through allegedly intermediate states for which there is no empirical evidence. Many characters were defined in a manner that demonstrates either a lack of understanding of, or disregard for, established methods and standards of morphological character coding. Some states display overlapping variation whereas others subsume variation that is not structurally or topographically similar. Polymorphic ''states'' were created for terminals with interspecific variation and unknown ''states'' for terminals that should have been scored unknown. Many characters were not evaluated for particular terminal taxa, but merely scored inapplicable although the structures and, consequently, the characters in question are present and therefore applicable to them. In view of the significant theoretical and empirical problems with the approach to cladistics taken by Soleglad and Fet, we find no justification for accepting either the results of their analyses or the revised classification derived from them. Pending the outcome of a rigorous phylogenetic analysis, published according to acceptable standards of scholarship in a peer-reviewed journal, we revert to the suprageneric classific...

Phylogenomic resolution of scorpions reveals multilevel discordance with morphological phylogenetic signal

“…All previous inferences of scorpion higher level relationships (and ensuing disputes) have been grounded in morphological characters, whose use may be limited in a group that exemplifies morphological stasis [22,24]. Despite widespread use of molecular sequence data for phylogenetic reconstruction, a scorpion phylogeny based on molecular data has yet to be proposed.…”

“…Paralleling the placement of scorpions among the arachnid orders, the internal phylogeny of scorpions has also long been contentious [16][17][18][19][20][21][22]. Numerous workers have historically emphasized different morphological characters of scorpions, resulting in variable hypotheses of phylogeny (figure 1), none of which has been generally accepted [21,22].…”

“…Numerous workers have historically emphasized different morphological characters of scorpions, resulting in variable hypotheses of phylogeny (figure 1), none of which has been generally accepted [21,22]. Traditionally, scorpions are divided into two morphologically distinct groups, the family Buthidae and the non-buthids [16,19,23].…”

Exploring the global animal biodiversity in the search for new drugs – Spiders, scorpions, horseshoe crabs, sea spiders, centipedes, and millipedes

“…The Scorpiones (the romanization of the Greek word 'skorpíos') comprise about 2,000 different species of predatory arachnids grouped in thirteen extant families [100]. They are characterized by the pair of pedipalps modified as grasping claws and the long, segmented tail often carried in a characteristic forward curve over the back with a venomous stinger at the end [101].…”

Notes on gestation periods and litter size in the arenicolous buthid scorpion Leiurus quinquestriatus (Ehrenberg, 1828) (Scorpiones: Buthidae)

“…Currently, the family Buthidae represents 81 (48.8%) of the 166 described scorpion genera and 700 (46.7%) of the approximately 1,500 described scorpion species (2). While all scorpions possess venoms, all but two of the approximately 30 to 50 medically significant species are members of the family Buthidae (3,4).…”