Phylogeny, ontogeny and adaptive radiation in the superfamily Tydeoidea (Acari : Actinedida), with a reappraisal of morphological characters

Hm. Andre et A. Fain, Phylogeny, ontogeny and adaptive radiation in the superfamily Tydeoidea (Acari : Actinedida), with a reappraisal of morphological characters, ZOOL J LINN, 130(3), 2000, pp. 405-448
Citations number
Categorie Soggetti
Animal Sciences
Journal title
ISSN journal
0024-4082 → ACNP
Year of publication
405 - 448
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The Tydeoidea as a whole (Tydeidae, Iolinidae and Ereynetidae) are analysed cladistically for the first time, based on a critical reappraisal of morph ological characters. In addition to the chaetotaxy, solenidiotaxy and poroi dotaxy, the following characters ale considered: form of dehiscence line; n umber of eyes; presence of a posterior trichobothrium; number of discs on g enital acetabula; breadth of cis-acetabulal area; sexual dimorphism (indica tive of true mating segmentation of legs and palps; presence and structure of ereynetal organ; shape of chelicerae and tarsus II and number of calypto stases. Special attention is paid to a comparative study of the segmentatio n and chaetotaxy of the palp within the superfamily. as well as to the pres ence of prodorsal eye-spots, variations of the posterior sensilla and the s egmentation of femur IV during ontogeny. Three types of phylogenetic analys es are employed: phenetic, cladistic and ontogenetic. The phenetic approach reveals that the current classification relies heavily on overall similari ty between taxa, especially in adults, supplemented by ontogenetic peculiar ities, such as the calyptostatic nymphs of Speleognathinae. The cladistic a nalyses lead to a reorganization of the Tydeoidea into four families. The M eyerellidae, characterized by the presence of three prodorsal eye-spots, in clude the Meyerellinae and Triophytydeinae. while the Tydeidae are restrict ed to Australotydeinae, Pretydeinae and Tydeinae. The remaining two familie s, Iolinidae and Ereynetidae, form the informal group Procurvata, character ized by the procurved dehiscence line. The family Iolinidae is enlarged to encompass the subfamilies Tydaeolinae, Pronematinae and Iolininae. The Erey netidae, characterized by the ereynetal organ and double genital discs, inc lude the Ereynrtinae :senior synonym of Pseudotydeinae, transferred from th e Tydeidae), Lawrencarinae and Speleognathinae. Minor discrepancies were fo und between the results for immatures and adults. These can be explained by ontogenetic trajectories that are not parallel and undergo a spectacular e xpansion into the character space as they extend. Within the Tydeoidea, div ersification and adaptation have occurred through acceleration, with adult adaptations extending into earlier stases. Heterostasy is only expressed in the Speleognathinae, in which the nymphs are all calyptostatic. The monoph yly of the Tydeoidea remains questionable, since the Meyerellidae might con stitute a separate group, more closely related to the Eupodoidea. The Meyer ellidae aside, the tydeoid mites seem to have originated from a group of fr ee-living forms that colonized the soil and related habitats and underwent an early radiation, giving rise to three major lineages: the Tydeidae, Ioli nidae and Ereynetidae. The Tydeidae are characterized by a low evolutionary rate combined with a high diversification indicative of a secondary adapti ve radiation within the Tydeoidea. In contrast, the Iolinidae are character ized by a high evolutionary rate combined to a low diversification. The thi rd lineage, the Ereynetidae, is highly diverse, showing high rates of evolu tion and speciation, linked to the adoption of endoparasitic habits. Differ ent hypotheses to explain the success and diversification in Tydeidae and E reynetidae are examined. (C) 2000 The Linnean Society of London.