Project 3216: M. I. Yavorskaya, E. Anton, P. Jaloszynski, A. Polilov, R. G. Beutel. 2018. Cephalic anatomy of Sphaeriusidae and a morphology-based phylogeny of the suborder Myxophaga (Coleoptera). Systematic Entomology. none yet (4):none yet.
Specimen: Priacma (unvouchered)
View: dorsal

Abstract

Myxophaga are a small group of beetles, but phylogenetically crucial as one of the four coleopteran suborders. The monogeneric Sphaeriusidae, one of four myxophagan families, comprise about 20 species, most of them living in moist substrate at river edges. The morphology of the minute hemispherical adult is very insufficiently known. Consequently, we document external and internal head structures using scanning electron microscopy, microtome sections and three-dimensional reconstructions. The results are discussed with respect to effects of miniaturization and also functional aspects, especially microphagous feeding habits. The head of Sphaerius is less affected by size reduction compared with other beetles of the same size class (e.g. larger Ptiliidae, Corylophidae). Features related to very small size are the absence of externally visible ridges and a partial shift of the brain into the prothorax. The cephalic musculature is apparently not affected. The feeding apparatus is similar to what is found in microphagous species of Polyphaga, especially in Scirtoidea and Staphyliniformia. However, in contrast to polyphagans with similar feeding habits, the hypopharyngeal longitudinal ridge (or process) of Sphaerius is strongly reduced and a fimbriate galea is lacking. The observed features are also evaluated in a cladistic analysis of larval and adult characters. The results are distinctly in conflict with branching patterns suggested by analyses of molecular data, but in agreement with previous morphological studies. In contrast to a pattern obtained in a recent molecular study (Hydroscaphidae + (Torridincolidae + (Sphaeriusidae + Lepiceridae))) our analyses yielded Lepiceridae as sister to the remaining Myxophaga (branch support 9), and Sphaerius as sister taxon of Hydroscaphidae (branch support 5). The monophyletic origin of the latter two taxa is supported by unusual synapomorphies of adults and larvae. Sphaerius is characterized by numerous autapomorphies of the head: a labro-mandibular locking device, a bipartite M. frontoepipharyngalis (M9) with subcomponents oriented in the opposite direction, a deep antennal furrow, an intercalary antennomere with a structure resembling a sucking disc, a strongly elongated flagellomere 1, a compact three-segmented antennal club, strong bundles of M. tentorioscapalis (M4) originating on the posterior head capsule, a concave anterior side of maxillary palpomere 2, and an elongated second pair of tormae posteriorly connected with a process of the hypopharyngeal suspensorium.


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Article DOI: 10.1111/syen.12304

Project DOI: 10.7934/P3216, http://dx.doi.org/10.7934/P3216
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 19 Taxa
  • 1 Specimen
  • 98 Characters


Download Project SDD File
Total scored cells: 1572
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 98
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 236
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:95/3
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MorphoBank Project 3216


    Members

    member name taxa specimens media chars character
    media
    labels
    cell scorings
    (scored, NPA, "-")
    cell
    medialabels
    rules
    Tanya Berardini
    Project Administrator
    Last logged in 07/02/18
    191198001572
    (1564, 0, 8)
    000
    Rolf Beutel
    Full membership
    Last logged in Never
    0000000
    (0, 0, 0)
    000
    MorphoBank Curator
    Full membership
    Last logged in Never
    0000000
    (0, 0, 0)
    000


    Taxonomic Overview for Matrix 'M25532' (19 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] Priacma
    Last Modified in 07/02/18
    3919104003
    [2] Helpless
    Last Modified in 07/02/18
    0989800003
    [3] Noterus
    Last Modified in 07/02/18
    1969601003
    [4] Trachypachus
    Last Modified in 07/02/18
    0989800003
    [5] Hydraena
    Last Modified in 07/02/18
    1989700003
    [6] Catops
    Last Modified in 07/02/18
    1979700003
    [7] Delevea
    Last Modified in 07/02/18
    12868600003
    [8] Satonius
    Last Modified in 07/02/18
    4939301003
    [9] Torridincola
    Last Modified in 07/02/18
    9898900003
    [10] Incoltorrida
    Last Modified in 07/02/18
    49484801003
    [11] Iapir
    Last Modified in 07/02/18
    10888800003
    [12] Ytu
    Last Modified in 07/02/18
    8909000003
    [13] Claudiella
    Last Modified in 07/02/18
    58404000003
    [14] Sphaerius
    Last Modified in 07/02/18
    3949401003
    [15] Hydroscapha
    Last Modified in 07/02/18
    0989800003
    [16] Scaphydra
    Last Modified in 07/02/18
    17818100003
    [17] Yara
    Last Modified in 07/02/18
    55434300003
    [18] Confossa
    Last Modified in 07/02/18
    54444400003
    [19] Lepicerus
    Last Modified in 07/02/18
    6929200003


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    Taxon list822
    Specimen list173
    Views for media list128
    Bibliography86
    Media views414Media search (343 views); M584622 (71 views);




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