Table 1.
Species included in the analyses.
The six outgroup taxa, Priapulus caudatus and Halicryptus spinulosus (Priapulida), Chordodes morgani and Gordius aquaticus (Nematomorpha), and Xiphinema rivesi and Trichinella spiralis (Nematoda), and 61 kinorhynch ingroup taxa, representing 60 kinorhynch species; inclusive collecting localities for specimens used for sequencing, accession numbers for sequences and source for coding of morphological characters.
Table 2.
Extraction, primer, PCR setting and sequencing information.
Summary of the choice of DNA extraction kit, primers, PCR settings and sequencing information, used by the four authors, HSR, HY, MDZ and MVS. 28S rRNA primers used by HSR are new and have not been published previously.
Fig 1.
Unrooted strict consensus of five most parsimonious trees of score 83, obtained from New Technology Search in TNT. Numbers at branches indicate bootstrap values.
Fig 2.
Summary trees showing results from analyses of the molecular sequence data.
A. Maximum Likelihood analysis and Bayesian Inference of combined 18S rRNA and 28S rRNA. Taxa with much missing information in the 28S rRNA marker have been omitted from these analyses. B. Maximum Likelihood analysis and Bayesian Inference of combined 18S rRNA and 28S rRNA. All taxa, including those with much missing information in the 28S rRNA marker, are included in these analyses. C. Maximum Likelihood analysis and Bayesian Inference of 18S rRNA. Support measures are indicated at the internodes as: ML bootstrap value/BI posterior probability. * means bootstrap value>95 + posterior probability = 1.00. Clades with ML bootstrap values <50 and BI posterior probabilities <0.95 are collapsed.
Fig 3.
Combined morphological and molecular tree.
Tree resulting from Bayesian Inference of combined morphological and molecular data sets. Numbers at branches indicate posterior probabilities.
Fig 4.
Scanning electron micrographs showing selected morphological character states for characters 1 to 6.
A. Mouth cone of Wollunquaderes majkenae showing articulated outer oral styles of equal sizes (character 1, state 0; character 2, state 0). B. Mouth cone of Dracoderes abei, with articulated outer oral styles alternating in size between larger and smaller (marked with *) ones (character 1, state 1; character 2, state 0). C. Outer oral styles in Campyloderes cf. vanhöffeni, being either absent or completely fused with mouth cone (character 3, state 2). D. Mouth cone with partly fused outer oral styles of Condyloderes sp. 1 (character 3, state 1). E. Mouth cone with soft, non-articulated outer oral styles of Pycnophyes communis (character 2, state 1). F. Mouth cone with soft, non-articulated outer oral styles of Pycnophyes kielensis (character 2, state 1). G. Introvert of New Genus, showing basally bifurcated primary spinoscalids (character 4, state 1). H. Detail from neck of Echinoderes microaperturus, showing a trichoscalid attaching to its trichoscalid plate (character 6, state 1). Abbreviations: oos, outer oral styles; pl, placid; psp, primary spinoscalids; tsc, trichoscalid; tsp, trichoscalid plate. Arrows indicate articulations of outer oral style units.
Fig 5.
Scanning electron micrographs showing selected morphological character states for characters 7 to 13.
A. Segment-like neck region of New Genus (character 7, state 1). B. Meristoderes macracanthus with its head retracted into the trunk, showing the closing mechanism with sixteen placids (character 8, state 1; character 9, state 5) arranged in a radial symmetrical pattern (character 13, state 0). Note also the smooth surface of the placids (character 10, state 0), and the distinct articulations between the placids and segment 1 (character 11, state 1). C. Dracoderes abei with its head retracted into the trunk, showing the closing mechanism with nine placids (character 8, state 1; character 9, state 3). The spacing between the dorsal placids makes the arrangement of the placids bilateral symmetrical (character 13, state 1). D. Condyloderes sp. 1 showing placids with various knobby projections (character 10, state 1). E. Two placids of Triodontoderes anulap. Note the distal tripartition (character 11, state 1) and the absence of distinct articulations between the placids and segment 1 (s1) (character 12, state 0). Abbreviations: pl, placids.
Fig 6.
Light micrographs showing selected morphological character states for characters 14 to 42.
A. Ventral view of segment 1 in Mixtophyes abyssalis, showing an undifferentiated sternal plate (character 16, state 0), and lateral projections at the anterior segment margin (white arrows) (character 14, state 1). B. Ventral view of segment 1 in Paracentrophyes anurus, showing a partly differentiated sternal plate (partial fissure marked with black arrows) (character 16, state 1), and lateral projections at the anterior segment margin (white arrows) (character 14, state 1). C. Ventral view of segment 1 in Pycnophyes greenlandicus, showing fully differentiated midsternal (ms) and episternal (ep) plates (character 16, state 2). Note also the lateral projections at the anterior segment margin (white arrows) (character 14, state 1). D. Ventral view of segments 2 and 3 in Echinoderes astridae, showing segment 2 forming a completely closed ring (character 19, state 0). E. Ventral view of segments 2 and 3 in Meristoderes macracanthus, showing partly differentiated lateral fissures (black/white arrows) on segment 2, but no midsternal fissure (character 19, state 1). F-G. Ventral view of segments 2 and 3 in Fissuroderes sorenseni (F) and Polacanthoderes martinezi (G), showing completely developed lateral and midsternal fissures (black/white arrows) on segment 2, and hence fully differentiated sternal plates (character 19, state 3). H. Ventral view of segments 10 and 11 in Wollunquaderes majkenae, showing midterminal (mts), lateral terminal (lts) and lateral terminal accessory spines (ltas) (character 38, state 1 and character 41, state 1). I. Ventral view of segments 10 and 11 in Paracentrophyes quadridentatus, showing its minute midterminal process (mtp) (character 41, state 0 and character 42, state 1).
Table 3.
The new kinorhynch classification.
Table 4.
Morphological character evolution in Kinorhyncha.
Fig 7.
Scanning electron micrographs showing selected morphological character states for characters 17 to 37.
A. Neck and segment 1 of Antygomonas paulae in ventrolateral view, showing the slightly sinuate anterior segment margin (arrow) (character 17, state 1). B. Neck and segment 1 of Semnoderes armiger in dorsal view, showing the deep middorsal incision in the anterior segment margin (arrow) (character 17, state 2). C. Neck and segment 1 of Sphenoderes poseidon in ventral view, showing the deep midventral incision in the anterior segment margin (arrow) (character 17, state 2). D. Segments 1 to 4 of Centroderes spinosus in ventral view, showing a straight anterior margin of the first segment (character 17, state 0), spinose midventral process (mvp) (character 23, state 1) and extraordinary long ventrolateral spines (vl) (character 33, state 1) present in the posterior margin. E. Segments 5 to 7 of A. paulae in ventral view, showing deep lateroventral notches (no) in the posterior segment margins (character 24, state 1). Note also the cuspidate spine (cu) (character 34, state 1). F. Segments 1 to 3 of Campyloderes cf. vanhöffeni in ventral view, showing extraordinary long lateroventral spines (lv) close to much shorter ventrolateral spines (vl) (character 32, state 1). G. Mid- and subdorsal parts of segments 3 to 5 in Pycnophyes sp., showing small non-articulated middorsal structures (nms) hardly projecting beyond the posterior segments margins (character 26, state 1). H. Segments 7 and 8 of Paracentrophyes anurus in lateral view, showing large non-articulated middorsal structures extended into spinose processes (spr) projecting beyond the posterior segment margins (character 26, state 0). Note also the small lateroventral setae (se) (character 27, state 1). I. Segments 3 to 5 of Dracoderes abei in dorsal view, showing alternatingly laterally displaced dorsal spines (character 30, state 1). J. Segment 2 of Pycnophyes kielensis in ventral view, showing male specific ventromedial tubes (vmt) (character 35, state 1). K. Segment 11 of Triodontoderes anulap in dorsal view, showing male specific crenulated spines (cs) in laterodorsal and middorsal positions (character 36, state 1). L. Segment 11 of D. abei in ventrolateral view, showing male specific penile spines (ps) (character 37, state 1).