identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03AF87E16B403D5A4786FF24FCD8A045.text	03AF87E16B403D5A4786FF24FCD8A045.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Allonothrus tuxtlasensis Palacios-Vargas & Iglesias 1997	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Redescription of  Allonothrus tuxtlasensis Palacios-Vargas &amp; Iglesias, 1997</p>
            <p>Taxonomy</p>
            <p> Family  Trhypochthoniidae (sensu lato; see below) </p>
            <p> Genus  Allonothrus van der Hammen, 1953</p>
            <p> Type species:  Allonothrus schuilingi Hammen, 1953 ; generic diagnosis: van der Hammen (1953), Wallwork (1960) </p>
            <p>Background</p>
            <p> Allonothrus tuxtlasensis is a Caribbean species, one of seven known from the Neotropics (Szywilewska-Szczykutowicz &amp; Olszanowski 2006). It was described based on collections from the state of Veracruz, Mexico (Palacios-Vargas &amp; Iglesias 1997) and its known distribution now includes the Mexican states of Quintana Roo, Chiapas, and Tlaxcala (Ermilov &amp; Yurtaev 2023, and unpublished records from J.G. Palacios-Vargas). It probably occupies all the Antilles, having been reported from several islands, extending from Cuba in the north to Trinidad in the south (Prieto Trueba &amp; Schatz 2004; Ermilov et al. 2016; Ermilov &amp; Smit 2017). All collections have been from decomposing leaf litter, but the habitats range widely, from forests (natural jungle, secondary woodlands) to organic residues on sandy soil of an abandoned coconut grove. </p>
            <p> The original description of  A. tuxtlasensis suffices for identification of the adult, but it lacks important details concerning the structure of gnathosoma and the chaetome of body and legs. These details are provided below, supported by line drawings, light photographs, and SEM images. Juveniles of  A. tuxtlasensis are not yet known, so we present previously unpublished developmental data for an Indian species—  A. giganticus Haq, 1978 —that was cultured by Palmer &amp; Norton (1990), to allow inferences about leg setation. </p>
            <p>Diagnosis</p>
            <p> Based on the original description (Palacios-Vargas &amp; Iglesias 1997) and supplemental data in our redescription we propose the following diagnosis for adult  A. tuxtlasensis . Genus-level characters are mostly omitted. </p>
            <p> Allonothrus species with body length: 495–585. Rostral seta medium-sized, thickened, densely ciliate; lamellar seta longest on prodorsum, heavily barbed, thick basally, becoming sub-spatulate (phylliform) distally; interlamellar seta short, usually phylliform, densely barbed, at base of small tubercle; bothridial seta long, distal half weakly clavate, densely barbed. Dorsocentral part of notogaster foveolate except near setae; without distinct posterior concavity but pygidial region with slight semi-elliptical depression. Notogastral setae heavily barbed, widest distally, dimorphic; c 1, c 2, c 3, cp, d 1, d 2,e 1, e 2 short, phylliform (mostly sub-spatulate); f 2, h 1, h 2, h 3, p 1, p 2, p 3 long, with thick isodiametric basal half, gradually broadened distal half. Epimeral, genital and adanal setae slightly thickened, densely barbed; 10 or 11 pairs of homogeneous genital setae; anal setae attenuate, roughened by inconspicuous minute barbs. Pretarsi homotridactylous; genua I and II with minute setiform organ σ m in place of genual pore; genu III with genual pore. </p>
            <p>Redescription of adult (Figs 1–7)</p>
            <p>Measurements. Body length 495–585; width 255–315.</p>
            <p>Integument. Color of preserved specimens medium reddish to yellowish brown. Body and legs covered by encrusting cerotegument with weakly and irregularly microtuberculate surface (Figs 2a, b; 7a, f), including localized regions of more distinct, larger surface granules (diameter up to 4). With additional adherent debris, especially in posteromedial part of notogaster between longer setae. Exocuticle densely porose, most conspicuously on prodorsum, coxisternum, and subcapitulum (Figs 3a, f, 6a).</p>
            <p>Prodorsum (Figs 1, 2, 3a). Triangular in dorsal view; rostrum evenly rounded except for small, paired lateral tooth (lt). Middle third with two topographic features: pair of curved medial carinae (mc), nearly meeting to form inverted-V shape; and pair of marked lateral swellings (sw) underlain by muscle sigilla and delineated by sharp groove and strong contours (lc) in transmitted light. Posterior third of prodorsum slightly raised behind medial carinae, with small, sharply defined medial depression (md) overlying several muscle sigilla, and pair of bulging, almost capsular bothridial lobes. Bothridial opening surrounded by raised rim (Fig. 2b); internally with cluster of short brachytracheae opening into region just external to seta bs insertion (Fig. 3c). Bothridial seta (86–94; Figs 2b, c, 3c) slightly and gradually broadened by isotropic cuticle in distal third, forming weakly clavate-spatulate head; barbs minute near base, distally becoming larger and overlapping. Rostral (ro), lamellar (le), and interlamellar (in) setae all heavily barbed but differing greatly in size and form: ro (41–49) nearly isodiametric, curving ventromediad, pair separated by about half their length; le (90–105) inserted on strong tubercle, proximally thick, isodiametric, distal third sub-spatulate, gradually flattening and doubling in width, pair close together, directed almost straight anteriad; in (13–15) inconspicuous, phylliform (fan-shaped), approximately as broad as long, cupped, with dense barbs on outer face (Figs 2d, 3c), inserted at base of small, triangular tubercle. Exobothridial setae both represented by vestiges; ex 1 on rim of bothridial lobe lateral to opening, represented by simple, inconspicuous microseta (1) hardly emerging from alveolus (Figs 2b, 3c); ex 1 ventral to bothridial lobe, represented only by alveolus, larger than that of ex 1.</p>
            <p> Notogaster (Figs 1–3). About 1.1–1.3 x longer than wide in dorsal view, broadest in posterior quarter, at level of opisthonotal gland (Figs 1a, d, 2a, e). Anterolaterally concave above legs III, IV (Fig. 2e) and below suprapleural carina (Fig. 1d, spc) running approximately between levels of lyrifissures ia and im; spc variably expressed according to body distension. Central region mostly with strong, well-spaced foveolae, round but of various diameters (up to 10); foveolae absent in general vicinity of setae (Fig. 3d, e) and laterally, ventral to spc. Without distinct larger concavities but pygidial region with shallow, semi-elliptical depression between setal pairs h 1 and ps 1 observable in dorsal view of cleaned specimens. Notogastral setae heteromorphic, all heavily barbed; c 2 directed anteriad, others generally posteriad. Setae c 1, c 2, d 1, d 2 (37–49), c 3 (22–26), cp, e 2 (30–41), e 1 (45–56) strongly phylliform-spatulate (Figs 2a, 7a); narrow at base, gradually broadened, flattened and cupped distally; inserted on small tubercles. More posterior setae— f 2 (86–94), h 1, h 2, h 3, p 1 (123–139), p 2 (75–101), p 3 (71–94)—thick and isodiametric in basal half or two-thirds, gradually broadened, flattened and cupped distally to various degrees but often less conspicuously so than shorter anterior setae (Figs 2a, 7b); inserted on large tubercles. Seta f 1 represented only by small alveolar vestige in smooth cuticle, anterior to seta h 1 (Figs 3e, 4a; see R4). Opisthonotal gland opening on low protuberance, anterodorsal to seta f 2 (Figs 1a, b, 4a). Lyrifissures ia, im, ip, ih in normal positions and except for ih of normal size and slit-like shape; ih unusually short and inconspicuous (Fig. 1a, c, d), sometimes visible only as alveolus;  ips inconspicuous (especially in contracted specimens), sub-cupular in form and located on softer cuticle of broad plicature region, seen directly or by transparency in distended or contracted specimens, respectively (cf. Figs 1c, 3h; see R5). </p>
            <p>Notes. Roman letters refer to normal setae (and famulus); Greek letters to solenidia; d σ and d φ indicate seta and solenidion coupled; prime (ʹ) designates seta on the anterior and double prime (ʺ) seta on the posterior face of a given leg segment; parentheses refer to a pseudosymmetrical pair of setae, collectively.</p>
            <p>Epimeral region. Coxisternum clearly in two units, with fused epimeres I/II separated from III/IV by narrow, but distinct ventrosejugal articulation (vsj, Figs 1c, 3f, g, 7d see R6). Apodeme ap.1 strongly oblique, ap.2 and ap.3 nearly transverse; all three meeting sternal apodeme (ap.st) at midline; ap.st inconsistently developed (Figs 1c, 3f), weakening posterior to ap.2, in mid-region of epimere II), and both anterior and posterior to ap.3. With narrow but distinct surface groove external to ap.2 and ap.3 (Fig. 7d). Epimeral setal formula 3-1-3-3 (I–IV); setae of different lengths (1a, 2a, 3a, 4b: 13–15; others: 30–34) but all slightly thickened, densely barbed throughout.</p>
            <p>Anogenital region (Figs 1c, d, 2a). Genital plates collectively trapezoid, 1–1.3 x wider than long; anteriorly with weak ridge along medial edge of each plate, effacing in posterior half. With row of 10–11 genital setae (30–37) aligned along medial edge but not isolated from rest of plate by sharply defined line or carina. Setae (30–37) slightly thickened, densely barbed throughout. Ovipositor (Fig. 6c) with general structure normal for family (Ermilov 2011a); length of distal part (beyond fold) 56, of which distal lobes comprise 19; setae ψ 1, and another (unidentified) τ-seta elongate, acute, narrowly spine-like (19); ψ 2 and two unidentified τ-setae short (7), thick, thorn-like, strongly bent in middle at nearly right-angle (Fig. 6e); six coronal setae (k) also short (9), thick, thorn-like, but nearly straight (Fig. 6d). Three pairs of adanal setae (22–26) setae appear slightly thickened by dense barbs; two pairs of anal setae (19– 26) attenuate, without conspicuous barbs. Lyrifissures iad and ian distinct, near anterior end of respective plates.</p>
            <p>Gnathosoma. Subcapitulum (Figs 4b, 6a. 8a, b) longer than broad: 90–101 × 71–86. With elements of both stenarthry and diarthry: oblique paired labiogenal articulation (scissure lgo) incomplete anteriorly, stopping just before reaching inferior commissure of mouth (Ji). Additional transverse articulation (scissure lgt) running laterally from Ji toward palp; genal seta m posterior to lgt (see R7). Rutellum atelobasic, with weak ventromedial expansion continuing distally as well-developed lamellate cutting edge (ce), fully covering terminal rutellar teeth from below; lateral lips and three pairs of homogeneous, relatively large (11–13), attenuate, mediodistally barbed adoral setae, all well exposed between Ji and rutellar expansion; rutellar brush (comb) comprising two ciliary rows on dorsomedial face; manubrial zone defined proximally by distinct fissure αf, distally by collum (c). Subcapitular setae a (15–19), m (7–9), h (15–22) attenuate, roughened by inconspicuous minute barbs, m thinner than a and h. Palp (Fig. 4c) length 49–52, tarsus about 1.5 x length of tibia; setation 0-1-1-2-9(+ω); ω short, baculiform; setae acm, sul, and (ul) with typical shape of eupathidia (smooth, blunted) but hollow interior not confirmed. Postpalpal seta (6) narrowly cylindrical (Fig. 6b), roughened by inconspicuous minute barbs. Chelicera (Fig. 4d) length 82–94; setae finely attenuate, cha (41–45) distinctly barbed, chb (17–22) nearly smooth (minutely roughened).</p>
            <p> Legs. Proportions shown in Fig. 5a–d; leg I about half body length. Pretarsi homotridactylous; claws strong, similar in size, minutely barbed on dorsal side. Formulas of leg setation and solenidia: I (1-6-5-6-16) [2-2-3], II (1-7- 5-5-14) [2-1-2], III (2-4-3-4-12) [1-1-0], IV (1-3-3-4-12) [0-1-0]; homology of setae and solenidia indicated in Table 1 (assumptions about tarsal setations and that of tibia I based on ontogeny of  Allonothrus giganticus ; Appendix 1). All or most setae on femora, genua and tibiae thick, heavily barbed. Famulus relatively long (13), acuminate. Tarsus  I solenidion ω 1 short, curving, blunt (baculiform); ω 2 and ω 3 thinner but longer, tapered (piliform), close together proximal to seta p ʺ; φ 1 subflagellate but shorter than closely coupled flagellate seta d; other solenidia comparatively short, baculiform to slightly tapered but rounded apically, with those of genua and tibiae much smaller than coupled seta d. Setae (p) eupathidial on tarsus I; s normal, with minute barbs. Genual pore present on genu III (Fig. 6j); replaced on genua I and II by minute (2–3), spiniform σ m (presumed solenidion; Figs 6f–i, 7e, f; see R9) </p>
            <p>Discrepancies with original description</p>
            <p> Our specimens of  A. tuxtlasensis from Mexico, Cuba, Grenada, and Trinidad are morphologically similar among themselves and are similar to the original description of Mexican type material (Palacios-Vargas &amp; Iglesias 1997) except as relates to two traits. (1) The interlamellar seta is strongly expanded (phylliform) and barbed in all our material, but setiform in the original description. (2) Some of the ventral setae illustrated in the original description have somewhat different relative length than in our material. At our request, Dr. Palacios-Vargas (pers. com. 2024) reinvestigated type specimens, and reported that the morphology of seta in varies in the type material (setiform to phylliform), and that apparent differences in the length of the ventral setae are mainly due to different drawing styles and methods of fixing specimens when drawing (temporary cavity slides versus permanent slides). </p>
            <p>Remarks on morphology</p>
            <p>1. Exobothridial setae</p>
            <p>Ancestrally in oribatid mites there are two pairs of exobothridial setae; each inserts in various positions posterolateral, lateral, anterolateral or (rarely) anterior to the bothridium. The different relative positions of the two have led to the application of several notations. When one is clearly more dorsal, they have been labeled exs and exi (or xs, xi; superior, inferior); when one is clearly more anterior the notations exa, exp (or xa, xp; anterior, posterior) have been used. Alternatively, they are simply numbered ex 1, ex 2. Homologies among the notations are sometimes uncertain but we believe that in most instances notations exs, exa, and ex 1 represent the same seta, with the other seta bearing the notations exi, exp, ex 2. 1 Since relative positions vary, we believe it is best to standardize notations using the numerical form. Of the two, ex 2 is most prone to loss and in such cases the remaining ex 1 usually is simply denoted ex, or x. Some generalities can be made in this regard: (1) among Palaeosomata and Parhyposomata both setae always are well-formed; (2) in Brachypylina ex 2 never forms but can be represented by a distinct vestigial alveolus (exv) in some early- to middle-derivative groups (Norton &amp; Ermilov 2021, their Remark #4). Within the other major groups various states exist, with the plesiomorphic state being both setae present, but either one (ex 2) or both setae can be absent or reduced to a vestige.</p>
            <p> In  Nothrina adults ex 2 is reduced to an alveolar vestige. In  Trhypochthoniidae usually this vestige (mark ‘ m ’ of Grandjean 1939a; his Fig. 3C, D) is distinct in the sclerotized adult, located near the margin of the aspis, while in juveniles it is less distinct and usually not on the aspis (which is less developed lateroventrally than in the adult). The vestige is visible in all instars in some genera (  Trhypochthonius ,  Mainothrus and  Archegozetes ), but in  Trhypochthoniellus it may be absent until the DN or even the adult. </p>
            <p> By contrast, ex 1 has more diverse development in this family. In the larva of all genera it is a distinct small- or medium-sized seta, and it retains this plesiomorphic form through ontogeny in  Mucronothrus and  Trhypochthoniellus , as it does in most other families of  Nothrina . In other trhypochthoniid genera it becomes highly reduced (  Mainothrus ; Ermilov 2021) or vestigial (  Trhypochthonius ,  Allonothrus ,  Archegozetes ) or may disappear entirely (  Afronothrus ). The nature of the vestige varies as well. In  Trhypochthonius it ranges from a simple pore-like canal (  T. tectorum ; Grandjean 1939a) to a minute but emergent seta (  T. triangulum Nakamura et al. 2013 ). In  Allonothrus tuxtlasensis a minute setal vestige barely emerges from the reduced alveolus on the projecting lateral wall of the bothridium (Fig. 2b). </p>
            <p>2. Bothridial porose organs</p>
            <p> In Mixonomata and  Nothrina a variety of porose organs can invaginate from the inner wall of the bothridium. In most instances these are air-filled respiratory organs (Norton et al. 1997) such as simple pouch-like pockets, saccules, sausage-like brachytracheae, or short tracheae. To our knowledge, the only report of such structures in  Trhypochthoniidae was for  Afronothrus , in which Wang et al. (1999) found a short, flat saccule invaginating from the bothridium (see our Fig. 9a). But in fact most  Trhypochthoniidae have such respiratory structures, though they may be less developed. Small pocket-like or saccule-like invaginations are present in  Archegozetes ,  Mainothrus and  Trhypochthonius (Fig. 9c–e), which seem similar to the bothridial saccules of  Platynothrus (Alberti et al. 1997) .  Allonothrus species have the greatest development of such structures in the family (Figs 3c, 9b). In the seven species studied by us (see Materials and methods) there is a small cluster of short brachytracheae, similar to those described for  Nothrus (Grandjean 1934; Tarman 1961; Călugăr &amp; Vasiliu 1979; Alberti et al. 1997) but fewer and more spreading. </p>
            <p>3. Trichobothrial regression</p>
            <p> Except for  Hermanniidae , in all examined  Nothrina the prodorsal trichobothrium is strongly regressed in the larva (Grandjean 1939a, his Fig. 3D; 1939b). The bothridial seta (‘sensillus’) is small, minute, or even absent, and the bothridium is undeveloped or shrunken to a narrow tube, such that the structure is similar to an apobasic seta (Grandjean 1956b; Călugăr &amp; Vasiliu 1979). As in most other  Nothrina , in  Trhypochthoniidae it usually becomes a normal trichobothrium during subsequent development, with the instar depending on taxon. In  Afronothrus ,  Archegozetes Trhypochthonius and  Mainothrus this is the PN, for  Allonothrus schuilingi the DN. In  Mucronothrus the regression persists until the adult, i.e. it is paedomorphic; the seta is well formed, but its insertion is apobasic, not really bothridial (Norton et al. 1996). In  Trhypochthoniellus the same may be true, according to species or, apparently, to genetic strain (Weigmann 1999). </p>
            <p> 1 One notable exception relates to  Nanhermanniidae . Grandjean (1954c) assigned xp to the larger, more dorsal seta on the bothridial wall of the adult: in the nymphs this seta is very slightly posterior to the lower small seta he considered to be xa. We think these notations are misleading. Because of the much larger size of his ‘ xp ’ and its more dorsal position, we believe it is the homologue of ex 1 (exs, exa) in other families. </p>
            <p>4. Notogastral seta f 1</p>
            <p> Of the 16 pairs of setae that comprise the fundamental (holotrichous) chaetome of the hysterosomal dorsum in oribatid mites, seta f 1 has been considered the weakest, the most prone to loss (Grandjean 1954a; Travé 1975; Haumann 1991). This regression has occurred in most Mixonomata, many  Nothrina , all Brachypylina except  Hermannielloidea , and probably all Astigmata (see summary in Norton &amp; Ermilov 2022). In the latter two groups, as well as the mixonomatan family  Eulohmanniidae , f 1 has disappeared without trace, but in most mixonomatans and nothrines, its loss is indicated by a persistent alveolar vestige. </p>
            <p> In  Nothrina , seta f 1 seems rather labile among higher taxa and even among species. In  Crotoniidae (sensu lato) the ancestral condition reflects that of the mixonomatan family  Perlohmanniidae (Grandjean 1958; Suzuki 1977), in which f 1 is present in the larva as a small seta, becoming vestigial in nymphs and adult. This is the state in the crotoniid subfamilies Camisiinae and Heminothrinae but in Crotoniinae f 1 is developed in all instars (Colloff &amp; Cameron 2009). Since crotoniines are derivative within the family (Domes et al. 2007b) the transition can be viewed as paedomorphic—retaining the larval presence through ontogeny—and explained by the removal or inactivation of whatever developmental mechanism caused its suppression in ancestors (Weigmann 2010). Several examples demonstrate this lability at the species level. Species of  Platynothrus (Lee 1985; his seta J4) and  Camisia (Colloff 1993) have been described with f 1 uniformly present in the adult, and Seniczak et al. (1990) reported variable development of f 1 in adults of  Platynothrus capillatus (Berlese, 1914) . Removal of ancestral suppression would be the simplest explanation for the holotrichous setation of  Nothridae and  Hermanniidae , as well as the brachypyline superfamily  Hermannielloidea . </p>
            <p> Trhypochthoniidae do not form seta f 1 in any instar, and f 1 vestiges have been reported or illustrated in the literature for adults of all genera except  Allonothrus . This may be because  Allonothrus species have a notogastral cuticle that is far more ornate than those in other genera and the simple, inconspicuous vestige has been overlooked. We found these vestiges in their usual position, aligned between setae e 1 and h 1, in  A. tuxtlasensis (Fig. 3e),  A. sinicus (Fig. 9l) and the other six  Allonothrus species we examined (see Materials and methods). </p>
            <p> It is clear that the suggestion of Badejo et al. (2002a) —i.e., that  Allonothrus species are holotrichous, and that describers have overlooked one pair of developed notogastral setae—is specious. While some descriptions and illustrations are of marginal quality, most are adequate and several are highly precise, with no real possibility that a seta as conspicuous as those of  Allonothrus species could be missed. Our finding of a setal f 1 vestige should remove any doubts about the ‘unideficient’ chaetome of  Allonothrus . Considering f 1 lability in other groups, the report by Badejo et al. (2002a) of holotrichy in  Parallonothrus is not unreasonable, but it has not been conclusively demonstrated (see below). </p>
            <p>5. Lyrifissures</p>
            <p> It seems likely that all  Trhypochthoniidae have the usual five pairs of notogastral lyrifissures, but they can have various forms and positions. Weigmann (1997b) considered a relatively large size of ia and ip to be a synapomorphy of  Malaconothroidea , but this is not a consistent trait in  Trhypochthoniidae , particularly in trhypochthoniid genera that were not part of his study, viz.  Afronothrus ,  Allonothrus and  Archegozetes . Lyrifissure ip was not discerned in some  Allonothrus studies (e.g. van der Hammen, 1953; Wallwork 1960, 1961), but its presence can be masked by the strong foveolation in this genus; it was found in the seven species we studied (see Materials and methods). </p>
            <p> In oribatid mites, lyrifissure  ips typically is located on the sclerotized cuticle of the notogaster, near its ventrolateral edge, but probably this is not true in most  Trhypochthoniidae . In  Allonothrus ips is off the sclerite, in the soft, foldable plicature zone (van der Hammen 1953; Wallwork 1961; Subías &amp; Sarkar 1982; Olszanowski &amp; Bochniak 2015; our Fig. 3h), where it has a somewhat cupular, rather than slit-like form. Whether one views  ips directly or by transparency depends on the degree of distention in the hysterosoma, but most illustrations of contracted specimens do not seem to make this distinction. Illustrations of well-distended specimens are more rare, but they show  ips in the plicature zone of at least some species of  Afronothrus ,  Mucronothrus ,  Mainothrus , and  Trhypochthonius (Ramani &amp; Haq 1992; Norton et al. 1996; Weigmann 1997b; Szywilewska 2004). By contrast,  ips seems to have a normal position on the edge of the notogaster in  Archegozetes . We are uncertain about  Trhypochthoniellus , but  ips also lies in the plicature zone in  Malaconothridae (Knülle 1957) , While this position is unusual among  Nothrina ,  ips also lies in the plicature zone of the mixonomatan families  Perlohmanniidae and  Collohmanniidae (Grandjean 1958; Norton &amp; Sidorchuk 2014), which leaves open the possibility that it is plesiomorphic if  Malaconothroidea is a basal nothrine taxon (see below). </p>
            <p>6. Ventrosejugal articulation</p>
            <p> Adults of  Trhypochthoniidae and  Malaconothridae are distinct among  Nothrina in having a divided coxisternum; i.e., a narrow transverse articulation (scissure) separates epimeres II and III. As such, they do not conform to the general body-form terminology proposed by Grandjean (1969) for oribatid mites having significant cuticular sclerotization. He proposed the term holoidy for the condition in which the proterosoma and hysterosoma are not independently movable: the usual key trait is that the coxisternum is undivided. Holoidy is found in all Brachypylina and most  Nothrina , and was the basis for the collective name of these two groups, Holosomata. 2 He contrasted this with dichoidy, in which a broad, ring-like sejugal (or ‘protero-hysterosomatic’) articulation allowed significant independence of the two secondary body regions, including relative motion—some degree of axial angular displacement in all directions—and some degree of telescoping. As he explained, dichoidy (or its derivative, folding defensive body form, ptychoidy) is found in the other major macropyline groups—Palaeosomata, Enarthronota, Parhyposomata and Mixonomata. Iconic mixonomatan examples include  Eulohmanniidae ,  Epilohmanniidae and  Perlohmanniidae . </p>
            <p> Grandjean (op. cit.) emphasized his view that dichoidy was not ‘primitive’ in the sense of being ancestral to holoidy, but he was silent about two important issues. First, he did not indicate what type of body form was ancestral to holoidy: if not dichoidy, then what? Certainly,  Nothrina and Brachypylina did not evolve their sclerotization patterns directly from an unsclerotized ancestor. Second, he left unexplained the problematic nothrine families  Malaconothridae and  Trhypochthoniidae , which are neither holoid (since they have a narrow but distinct ventrosejugal articulation) nor dichoid (since this narrow articulation serves only as a hinge, allowing slight dorsoventral flexing but not lateral relative motion or telescoping). Weigmann (1997b) called this narrow articulation between epimeres II and III a ‘weak transversal zone’; for brevity, we coin the term subholoid for this condition (noun = subholoidy). </p>
            <p> Without using specialized terminology, Knülle (1957) illustrated his interpretation of the transition from subholoidy to holoidy, referring to a ‘Trhypochthonoidea-stage’ (his Fig. 21) with a narrow ventrosejugal articulation, and a ‘  Nothrus -stage’ with a fused coxisternum (his Fig. 22). In effect, he viewed the ventrosejugal articulation as plesiomorphic in  Nothrina (= Nothroidea). Haumann (1991, p. 144) specifically indicated that holoidy evolved from dichoidy, though he did not characterize the condition in  Trhypochthoniidae and  Malaconothridae as intermediate. For support, he quoted Grandjean (1969), but it was a misinterpretation: the cited text was a hypothetical ‘strawman’ statement that Grandjean immediately rejected in the next sentence (see above). </p>
            <p> Overall, the ideas promoted by the three German authors might be distilled as: subholoidy was derived from dichoidy by narrowing of the ventral part of the sejugal articulation, and holoidy derived from subholoidy by elimination of the articulation. In this view,  Trhypochthoniidae and  Malaconothridae form the sister-group of Holosomata (see Fig. 11a); we examine this issue further below, in a section that addresses inferences from molecular studies. </p>
            <p> An important point is that the subholoid state is not restricted to  Trhypochthoniidae and  Malaconothridae . Norton &amp; Metz (1980) described it in the mixonomatan family  Nehypochthoniidae , though they used no special terminology. Norton &amp; Sidorchuk (2014) followed Grandjean (1969) in applying the term dichoid to another mixonomatan family,  Collohmanniidae , but in effect they described the subholoid condition in these mites, which have a very narrow ventral articulation and lack the independent movement of proterosoma and hysterosoma found in truly dichoid families. </p>
            <p>Whether these examples represent separate evolutions of subholoidy from dichoidy is unknown, but three other examples of narrowing in the ventral component of the sejugal articulation are certainly convergent. Grandjean (1969) promoted the idea that dichoidy was ancestral to ptychoidy, the defensive body form in which the aspis can swing down to cover the retracted legs (Sanders &amp; Norton 2004 and included references). This functionality requires the coxisternum to fold in half precisely, and it has this capability because the ventral component of the sejugal articulation became very narrow, hinge-like. Grandjean (1969) noted three evolutions of ptychoidy in oribatid mites, which implies three different times in which a broad, dichoid-type sejugal articulation evolved into one with a narrow, hinge-like ventral component. Grandjean did not focus on this point, but in essence he accepted such an evolutionary reduction in the ventral component of ptychoid groups, while apparently rejecting such a transition during the evolution of holoidy.</p>
            <p>2 Grandjean (1969) specifically noted that the name was coined for convenience, not in a taxonomic or phyletic sense, but Balogh &amp; Mahunka (1979) formally proposed Holosomata as a taxon with the rank of supercohort.</p>
            <p> As discussed below, in molecular studies  Malaconothridae usually have been recovered as basal in  Nothrina , or nearly so. This would be consistent with the idea that subholoidy is a transitional state between dichoidy and holoidy. But a possible alternative origin for subholoidy in  Trhypochthoniidae is suggested by some molecular trees in which this family lies in the midst of holoid  Nothrina (e.g., Fig. 11e). Typically, the coxisternal sclerotization of juveniles in holoid groups is fragmented, so it might also have arisen as a paedomorphic (neotenic) trait. Overall, paedomorphic trends could explain many of the setal reductions that characterize  Trhypochthoniidae (Norton 1998) and an effective reversal from holoidy might be another manifestation, if indeed this family evolved in the midst of holoid  Nothrina . </p>
            <p>7. Subcapitular structure and the evolution of diarthry</p>
            <p> A striking feature of  Trhypochthoniidae is that—despite the absence of specialized chelicerae—they exhibit the widest range of subcapitular structure of any oribatid mite family (Table 4). In his classic synthesis on the morphology and evolution of the oribatid mite subcapitulum (‘infracapitulum’), Grandjean (1957) recognized three general forms that relate to the presence and nature of paired labiogenal articulations (lg) on the ventral face. Such articulations allow small relative movement of the paired malapophyses (the supposed coxal endites of the palpal segment, the ventral surface of which is the gena), each bearing a distal rutellum. The articulation allows flexing, such that the rutellum maintains contact with the retracting chelicera, providing a scissoring action to cut food fragments (van der Hammen 1980; Evans 1992). A stenarthric subcapitulum has an oblique pair of labiogenal articulations leading posterolaterally from the mouth (commissure Ji); these circumscribe a triangular mentum, considered the sternum of the palpal segment. In a diarthric subcapitulum lg runs laterally from the mouth to the base of each palp, circumscribing a rather quadrate ‘mentum’ (see below). An anarthric subcapitulum lacks such ventral articulation, either because it is not significantly sclerotized or—if sclerotized—because other features preclude the need for an articulation. While the forms have a somewhat mosaic distribution, in general anarthry characterizes endeostigmatid outgroups of  Oribatida , as well as some Palaeosomata and most Enarthronota, and was interpreted by Grandjean (1957) as the most primitive form. Stenarthry characterizes most middle-derivative groups, and diarthry (or its derivatives) characterizes the Brachypylina. </p>
            <p>In this conceptual model, with increased levels of sclerotization stenarthry evolved from anarthry by the evolution of an oblique lg to allow flexing of the malapophyses, and diarthry evolved from stenarthry by a change in the trajectory of lg. Grandjean did not discuss how or why this latter change might have occurred but—since the terminology (mentum, genae, lg) does not vary between the types —presumably he did not question the homology of lg or the sclerites it separates in the two articulated forms. We know no intermediate states that would support the idea that the trajectory of lg changed gradually, so how did diarthry arise?</p>
            <p> The subcapitular forms in  Hermanniidae suggest one likely pathway to diarthry.While many of its species exhibit typical stenarthry with a long, oblique lg running from the mouth to the posterolateral margin of the subcapitulum (e.g. van der Hammen 1968), others have an incomplete articulation, with lg progressing only a short distance posterolaterad from the mouth (e.g., Figs 19, 23 in Woas 1978, Figs. 1, 8 in Woas 1981). Such an abbreviated lg may have subsequently extended further laterad toward the palp base, to create a diarthric subcapitulum typical of Brachypylina. 3 </p>
            <p> Allonothrus shows us another potential pathway between stenarthry and diarthry, and also demonstrates that the two forms of labiogenal articulations may not always be homologous. As Woas (2002) noted, the subcapitulum has a variety of forms in what he referred to as the ‘  Allonothrus group.’  Allonothrus sinicus , for example, exhibits typical stenarthry (Fig. 8c). By contrast, the subcapitulum of  A. tuxtlasensis (also  A. malgorzatae ) has elements of two articulations and might be characterized as ‘duplex’. In  A. tuxtlasensis the oblique articulation (lgo) is incomplete anteriorly (opposite to that of some  Hermanniidae ), not quite reaching the mouth, while a transverse articulation (lgt) runs laterad from the mouth (Figs 4d, 6a, 8a, b). Seta m, generally associated with the gena in oribatid mites, is posterior to lgt in the duplex type, whereas it is anterior to lg in the typical diarthric subcapitulum of Brachypylina and in the shortened, near-transverse lg of some  Hermanniidae (see above). </p>
            <p> 3 The close relationship generally assumed for  Hermanniidae and Brachypylina (Haumann 1991; Weigmann 2006) has not been supported by molecular studies (see below). </p>
            <p> It is easy to envision the loss (by fusion) of the oblique articulation altogether, and this may have occurred during the evolution of diarthry in  Afronothrus (Fig. 8d) and  Trhypochthoniellus (Weigmann 1996; his Fig. 1C). While their illustrations were crude and difficult to interpret, Badejo et al. (2002a) described such conditions in  Parallonothrus :  P. nigeriensis has a transverse articulation but the additional oblique line was implied to be a nonfunctional ridge; by contrast,  P. brasiliensi s purportedly possesses only the transverse articulation. Unfortunately, much literature on  Trhypochthoniidae does not distinguish between a functional articulation and a simple ridge or line of fusion, </p>
            <p> Weigmann (1996) had a different view: he promoted stenarthry as the ancestral condition in oribatid mites, and envisioned anarthry as a transitional condition during the evolution of diarthry in  Trhypochthoniellus ; i.e. its ancestors entirely lost the oblique articulation, then evolved the transverse one anew. We believe such a pathway is unlikely. In essence, it was imposed by a constraint: the relationships perceived in his cladogram (his Fig. 2; our Fig. 8b; see also Knülle 1957; Weigmann 1997b), in which  Trhypochthoniellus is sister-group to the anarthric  Malaconothridae . The inferred relationship was based primarily on other traits, and if—as we believe—  Trhypochthoniellus is instead part of a monophyletic  Trhypochthoniidae (sensu lato; see below) the constraint is removed. </p>
            <p>This brings up a terminological problem, first touched on by Weigmann (1996; see also Alberti &amp; Coons 1999). Theoretically, if the triangular mentum of a stenarthric subcapitulum represents the sternite of the ancestral palpsegment, and each paired gena represents only the venter of the coxal endite (i.e., the malapophysis; see also van der Hammen 1968, 1980), then the region that is lateral to the triangular mentum and basal to the palp—which must derive from the ancestral palp coxa—has no designation. It remains problematic, but whether this interpretation is correct or not, and despite common usage, the ‘mentum’ of stenarthric and diarthric subcapitula are not fully equivalent.</p>
            <p>8. Structure of the rutellum</p>
            <p> Based on outgroup comparisons with mixonomatans, the plesiomorphic form of the rutellum in  Nothrina is atelobasic—i.e., not reaching the midline at its base, such that lateral lips are at least partly exposed—with a simple dentate distal margin (Grandjean 1957). Among  Trhypochthoniidae this combination is best exhibited by  Mucronothrus and  Trhypochthonius , but modifications have occurred both proximally and distally. While most  Trhypochthoniidae have an atelobasic rutellum, it is somewhat variable in  Allonothrus . In  A tuxtlasensis , the lateral lips are well exposed (Figs 4b, 8a), while in  A. malgorzatae the rutellum seems pantelobasic, with no exposure of the lateral lips. Distally, the rutellum can be modified by the development of a variably-developed distal cutting edge (ce), such that the terminal dentition is hidden in ventral view. This edge is strongly developed, lamellate, in  Afronothrus (Fig. 8d) and  Trhypochthoniellus but in  Archegozetes it is rudimentary, represented by a simple transverse carina (see Fig. 3 in Alberti et al. 2011). The edge seems similarly variably among species of  Allonothrus (cf. Fig 8a, 8c), and  Mainothrus (cf. Weigmann 1997a; Bayartogtokh &amp; Yondon, 2019). </p>
            <p>9. Genual pore and setiform organ σ m</p>
            <p> As first reported by Grandjean (1940a), in various middle-derivative families of Mixonomata and  Nothrina the genu of leg I bears a so-called genual pore. Despite its name, it does not open to the surface: it is a simple, well-defined canal passing through the procuticle (‘ectostracum’) but not the epicuticle (‘epiostracum’). He noted (see also Grandjean 1954c, 1958, 1966) that the genual pore has a somewhat mosaic distribution—present in some Mixonomata (including Ptyctima,  Epilohmanniidae ,  Collohmanniidae and  Perlohmanniidae ) and  Nothrina (  Nanhermanniidae , some ‘Camisiidae’, some  Trhypochthoniidae ) but not others—and that in some groups a metameric homologue is present also on genua II and III, but never IV. </p>
            <p> Among  Trhypochthoniidae , the pores can be found on genua I–III in representatives of all terrestrial and semiaquatic genera: they were reported previously in  Trhypochthonius (Grandjean 1940a) and  Mainothrus (Ermilov 2021) , and with new observations we confirm their presence on these same genua in  Afronothrus ,  Archegozetes , and some  Allonothrus species (Table 2; Fig. 9). Each is located posterior to the coupled d σ, but at various distances (cf. Fig. 9f, g). Conversely, we confirm that genual pores are absent from  Trhypochthoniellus (Grandjean 1940a) and  Mucronothrus (Norton et al. 1996) , which are the two genera specializing in aquatic habitats (Behan-Pelletier &amp; Eamer 2007; Schatz &amp; Behan-Pelletier 2008). The habitat correlation suggests that the pores have some function and that the cuticular canal includes a dendritic extension, but this has not been investigated. </p>
            <p> Regarding its origin, Grandjean (1940a) speculated that the pore could be a vestige of either a lost solenidion or an ancestral lyrifissure. He later (1954c) dismissed the first idea, but without explanation. He did not dismiss the second but expressed a lack of confidence in the idea. In fact, lyrifissures are not found on the genu of any acariform mite, so to us it seems an unrealistic explanation. Grandjean implied the pore could be a newly evolved structure, rather than a vestige, but in either case it would be apomorphic, since the pore is not present in the more basal oribatid mite groups (Palaeosomata, Enarthronota, Parhyposomata) or outgroups in Endeostigmata. Regardless of its origin, the mosaic pattern in Mixonomata and  Nothrina , and absence in the derived group Brachypylina, suggest that the genual pore was lost multiple times. </p>
            <p> Allonothrus provides us with additional insight, if not a certain solution, regarding the origin of these pores. Ermilov &amp; Bakowski (2021) first noticed a small novel ‘seta’ (their d *) on genua I and II of  A. malgorzatae , though they did not discuss it.  Allonothrus tuxtlasensis has identical structures that we denote σ m, and these are present on other species of the genus, but not all (Table 2). We believe each σ m is homologous with a genual pore because the two structures never co-occur, and σ m occupies the same place on genua I and II—posterior to coupled d σ—as does the genual pore in other species (cf. Fig. 3h, k). </p>
            <p>Notes. * = genual pore very close to insertion of seta d and coupled solenidion (Fig. 9j).</p>
            <p> The presence of σ m suggests that Grandjean’s first idea might have been correct: i.e., the genual pore seems to have some historical connection with a solenidion. For several reasons, we believe σ m may represent the atavistic reappearance of solenidion σ 2. First, σ m is isotropic—not birefringent in polarized light—among the known setiform organs of oribatid mites only solenidia are isotropic (Grandjean 1935; Alberti &amp; Coons 1999). Like solenidia, σ m also is hollow and appears to attach directly to the soft alveolar cuticle, rather than having an inserted solid ‘root’ that would characterize a seta. In σ m we have not seen the transverse striations that typically appear when solenidia (which are multiporous chemosensilla) are viewed with transmitted light, but these striations often are indiscernible in small solenidia. While solenidia rarely are so small, the palaeosomatan genus  Aphelacarus has several that seem similar in form to σ m and Grandjean (1954b) considered these ‘vestigial.’ </p>
            <p> Positional analogy with the tibia can lend support to this idea. Whether in the form of a pore or σ m, the structure on genu I has the same position relative to the coupled d σ that φ 2 has to the coupled d φ 1 on tibia I. Positional similarity among taxa led A. Seniczak et al. (2023) to independently (without reference to Grandjean’s studies) consider the genual pore of  Nanhermannia to be a vestigial second solenidion, σ 2: they offered no reason, but as explained by S. Seniczak (pers. comm. with R.A.N., 2024) it has a position similar to σ 2 in  Lohmanniidae . </p>
            <p> Uncertainties remain, however, and these may have led Grandjean (1954c) to dismiss his original idea of a solenidial origin for the pore. Perhaps most important is that σ 2 and the genual pore are not mutually exclusive in all groups. In the larva of both  Perlohmannia and  Collohmannia genu I bears a genual pore in addition to two solenidia (Grandjean 1958, 1966; Suzuki 1977). If their pore is a solenidial vestige, it must be from a third ancestral solenidion. A third genu  I solenidion is rare outside Palaeosomata; it occurs in the mixonomatan family  Eulohmanniidae , though it forms in the PN (Norton &amp; Ermilov 2022; Ermilov &amp; Norton 2023). Also, while a genual pore can occur on genu III in addition to the usual σ, no known oribatid mite has a second solenidion on that segment, and to our knowledge only members of  Parhypochthoniidae , perhaps the earliest derivative family of Novoribatida, have a second solenidion on genu II. A distant outgroup, the endeostigmatid family  Alycidae (e.g.,  Pachygnathus ,  Petralycus ; Grandjean 1937, 1943) includes species with two solenidia on both genua II and III, so σ 2 may have existed on these segments in distant oribatid mite ancestors. </p>
            <p> Another complication is that the pore may be doubled on genu I. We know of only one published observation (Grandjean 1958;  Perlohmannia ), but we have also seen an isolated example in a large, undescribed species of  Epilohmannia (R.A.N., unpublished). We consider such rare doubling to be developmental anomalies, similar to the occasional doubling of setae. </p>
            <p> If σ m is a homologue of solenidion σ 2, it is atavistic, representing a reversal that we presume resulted from the removal or inactivation of a long-standing genetic or epigenetic suppression that effected its initial disappearance (Weigmann 2010), similar to the reappearance of notogastral setae f 1 (see above). This possibility is relevant also to a different phylogenetic issue, the origin of Astigmata from within oribatid mites. While there are different specific hypotheses for their origin based on morphological (Norton 1998) or molecular (e.g., Dabert et al. 2010; Klimov et al. 2017) data, each infers that σ 2 reappeared on genu I in the ancestor of Astigmata. Norton (1998) mentioned possible examples of solenidial reappearance on tarsi, but the  Allonothrus examples gives more credibility to the specific reappearance of σ 2. </p>
            <p>10. Shape of tarsal setae</p>
            <p> The shapes of ventrodistal leg setae in  Allonothrus species —pairs (p), (u), (a) and s —are typical of terrestrial oribatid mites in being attenuate, with finely tapered tips that probably increase adhesion to substrates in a gaseous medium. The same is true of species in  Archegozetes ,  Trhypochthonius and  Mainothrus . The latter two genera have species that inhabit damp environments such as bogs and fens (Weigmann et al. 2015; Behan-Pelletier &amp; Lindo 2023), but they are not aquatic mites.  Afronothrus also have normal leg setae and are usually associated with a variety of terrestrial habitats (see Wang et al. 1999 for overview). An unidentified  Afronothrus species was considered ‘aquatic’ by Pepato et al. (2022), since abundant adults and juveniles were active in free water held in the leaf axils of a soil-growing bromeliad in Florida (P.B. Klimov, pers. comm. with R.A.N., 16-i-2023), but we suspect this was an opportunistic association. </p>
            <p> By contrast, species of  Mucronothrus and  Trhypochthoniellus are truly aquatic, associated with both lentic and lotic habitats (Norton et al. 1988; Weigmann &amp; Deischel 2006; Behan-Pelletier &amp; Eamer 2007; Schatz &amp; Behan-Pelletier 2008). The ventrodistal setae on tarsi II–IV are very short, acute or conical, lacking the fine tips of the terrestrial genera. Such setal shapes also characterize  Malaconothridae , many of which are aquatic or live in wet organic soils. This has been considered a synapomorphy with  Trhypochthoniellus (Weigmann 1997b) but, as discussed below, molecular data do not support this relationship. </p>
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	https://treatment.plazi.org/id/03AF87E16B403D5A4786FF24FCD8A045	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B513D594786F9C4FD96A775.text	03AF87E16B513D594786F9C4FD96A775.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trhypochthoniidae (Norton 1998)	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Trhypochthoniidae</p>
            <p>General comparison</p>
            <p> After studying a wide range of taxa and relevant literature, it is clear that leg setation in  Trhypochthoniidae has both significant variety—perhaps more than any other nothrine family—and a unique set of consistent traits that could serve to diagnose the family. Leg setation has been misinterpreted in some literature, largely due to a lack of knowledge of ontogeny, which can be crucial to establishing setal homologies (Grandjean 1941a; Norton &amp; Ermilov 2014). </p>
            <p> The full ontogeny of leg setation has been reported for only four of the seven currently recognized genera:  Afronothrus ,  Mucronothrus ,  Mainothrus , and  Trhypochthoniellus . Fragmentary ontogenetic data for  Trhypochthonius have been presented by F. Grandjean in various papers (see Norton &amp; Ermilov 2014), and some data on tarsi of  Allonothrus schuilingi and  Archegozetes magnus were presented by van der Hammen (1955b), but these are insufficient for detailed comparisons of genera and families. Below, we review the salient aspects of leg setal ontogeny for each of the seven genera. Included are ontogenetic tables for representative species of  Allonothrus ,  Archegozetes and  Trhypochthonius . </p>
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	https://treatment.plazi.org/id/03AF87E16B513D594786F9C4FD96A775	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B523D594786FEF8FBA3A455.text	03AF87E16B523D594786FEF8FBA3A455.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Afronothrus Wallwork 1961	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Afronothrus</p>
            <p> Wang et al. (1999) presented the ontogeny of leg setation in  A. incisivus . Notable traits include; the presence of four larval setae (including cʺ) on tibia I, with a final complement of five; the absence of cʺ from larval tibia II, with a final complement of four; the absence of several fundamental tarsal setae, including the primilateral pair (pl) from tarsus I, primiventral setae (pv) from tarsi II and III, and fastigial seta ftʹ from tarsus III. Pair (a) form on tarsi I–III, seta aʹ forms on tarsus IV, but aʺ does not. Regarding accessory setae, the iteral pair (it) are absent; the adult forms proximal setae on each tarsus: v A ʹ on all, plus l A ʹ on tarsus I and v A ʺ on tarsus II. </p>
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	https://treatment.plazi.org/id/03AF87E16B523D594786FEF8FBA3A455	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B523D594786FDD8FE46A281.text	03AF87E16B523D594786FDD8FE46A281.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Allonothrus van der Hammen 1953	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Allonothrus</p>
            <p> Our knowledge of setal ontogeny is based on an unpublished study of  Allonothrus giganticus from Kerala, India. This name is a senior subjective synonym of  Allonothrus pararusseolus Subías &amp; Sarkar, 1982 from Tripura, India (new synonymy). The latter authors seem to have been unaware of Haq’s (1978) publication. One of us (R.A.N.) studied specimens from the type locality, identified by M. Haq, and had  A. giganticus in culture. While the verbal description of  A. giganticus is sufficiently detailed, the illustrations are somewhat misleading. As examples: seta le was drawn as hardly exceeding the rostral margin (his Fig. 5), but actually it far overhangs; the notogaster seems illustrated with 16 pairs of setae, but h 3 is duplicated in dorsal and ventral views; genital setae appear to be uniform (his Fig. 6) but the posterior two pairs are simple, not barbed like the others. These and other features were more accurately illustrated by Subías &amp; Sarkar (1982). Neither paper mentioned a posterior notogastral cavity in the pygidial region, but an indistinct one is present in studied specimens. </p>
            <p> Appendix 1 presents the ontogeny of setiform organs of  A. giganticus . Previously, a small part of this information was published by Wang &amp; Norton (1988). Notable traits include; the presence of four larval setae (including cʺ) on tibia I, with a final complement of six; the absence of cʺ from larval tibia II, with a final complement of five; the absence of several fundamental tarsal setae, including primilateral setae (pl) from tarsus I, primiventral setae (pv) from tarsi II and III, fastigial seta ftʹ from tarsus III, and antelateral (a) setae from tarsus IV. Regarding accessory setae, the iteral pair (it) are absent and the adult forms proximal setae on each tarsus: pair (l A) on tarsus I; l A ʹ on II, and pair (v A) on II–IV. </p>
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	https://treatment.plazi.org/id/03AF87E16B523D594786FDD8FE46A281	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B523D584786FAA4FC90A691.text	03AF87E16B523D584786FAA4FC90A691.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Archegozetes Grandjean 1931	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Archegozetes</p>
            <p> Archegozetes longisetosus , originally collected from Thailand (Aoki 1965), is a widespread tropical-subtropical species (Subías et al. 2012). Adult legs were illustrated by Beck (1967; his Figs 6–9), but no ontogenetic data were presented. Most setae were not labelled, but several errors can be corrected. (1) The three solenidial notations on tarsus I (Beck’s Fig. 6) are incorrect, based on our observations and on ontogenetic studies of tarsus I in the similar  A. magnus by van der Hammen (1955b): using the standard ontogenetic sequencing, Beckʹs ω 1 should instead be ω 3; his ω 2 should be ω 1; and his ω 3 should be ω 2. 4 (2) On tibia I (his Fig. 6), the seta labelled vʺ is actually larval seta cʺ (vʺ does not form). </p>
            <p>Appendix 2 presents the ontogeny of setiform organs based on specimens from Costa Rica, complemented by observations from cultured Puerto Rican specimens (see Heetoff et al. 2013). Notable traits include: the presence of four larval setae (including cʺ) on tibia I, with a final complement of five; the absence of cʺ from larval tibia II, with a final complement of four; the absence of several fundamental tarsal setae, including the primilateral pair (pl) from tarsus I, primiventral setae (pv) from tarsi II and III, and fastigial seta ftʹ from tarsus III 5. Seta d is coupled with the respective solenidion on genua and tibiae I, II, but on tibiae III, IV and genu III they are noticeably separated. Both antelateral setae (a) are formed on tarsus IV. Regarding accessory setae, the iteral pair (it) are absent and the adult forms proximal setae on tarsi I–III and sometimes IV. The number of proximal accessory setae is variable and we did not study the statistics. But at least one lateral (l) pair forms on tarsi I and II, in addition to one or more ventral pairs (v); tarsus III seems to form only ventral setae; tarsus IV forms only vʹ or none. The tarsal variation in adults reported by Beck (1967) is certainly related to these setae.</p>
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	https://treatment.plazi.org/id/03AF87E16B523D584786FAA4FC90A691	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B533D584786FE94FED4A499.text	03AF87E16B533D584786FE94FED4A499.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Mainothrus (Ermilov 2021)	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Mainothrus</p>
            <p> Seniczak et al. (1998) presented the setal ontogeny of  M. badius . Adult legs were illustrated by Weigmann (1997a), under the name  Altrhypochthonius badius , but notations were not applied. Salient features include: the presence of four larval setae (including cʺ) on tibia I, with one added during development for a total of five; the absence of cʺ from larval tibia II, with a final complement of four; the presence of pair (pv) on tarsi I and IV but their absence from II and III; the presence of pair (a) on tarsi I–III, but only aʹ on IV. Regarding accessory setae, pair (it) are absent; pair (v A) form on all tarsi, with tarsus I additionally forming lʹ A. As in some  Allonothrus species , on tarsus I of  M. badius and  M. paratransaltaicus Ermilov , 20216 seta ftʺ is strongly regressed (a minute spine) and near solenidion ω 1. Pair (pv) were indicated for tarsus II and III of  M. paratransaltaicus (his Fig. 2), but ontogeny is unknown in this species, and we suspect these are instead accessory ventral setae (v), as in  M. badius . Also, we suggest that—based on the illustrations—the tarsus IV setation of both  M. paratransaltaicus and  M. transaltaicus Bayartogtokh &amp; Yondon, 2019 is identical to that of  M. badius , i.e. with pairs (pv) and (v A), but with only one antelateral seta, aʹ. </p>
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	https://treatment.plazi.org/id/03AF87E16B533D584786FE94FED4A499	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B533D584786FCACFC14A25D.text	03AF87E16B533D584786FCACFC14A25D.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Mucronothrus	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Mucronothrus</p>
            <p> Norton et al. (1996) presented the ontogeny of leg setation in  M. nasalis . Notable traits include; the presence of four larval setae (including cʺ) on tibia I, with none added during development; the absence of cʺ from larval tibia II, with a final complement of four; the absence of several fundamental tarsal setae, including the primilateral pair (pl) from tarsus I, primiventral seta pvʺ from tarsus I and pair (pv) from tarsi II and III, and fastigial seta ftʹ from tarsus III. Of the antelateral setae, pair (a) form on tarsi I–II, only seta aʹ forms on tarsus III, and neither forms on IV. 7 Regarding accessory setae, the iteral pair (it) are absent; the adult lacks proximal setae on tarsus I, and usually IV, but one vʹ seta forms on tarsus III and one or two form on tarsus II. </p>
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	https://treatment.plazi.org/id/03AF87E16B533D584786FCACFC14A25D	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B533D574786FBD0FE1CA409.text	03AF87E16B533D574786FBD0FE1CA409.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trhypochthoniellus (Weigmann 1997)	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setation in  Trhypochthoniellus</p>
            <p> Seniczak et al. (1998) presented the setal ontogeny of  T. longisetus (Berlese, 1904) under the synonym  T. crassus (Warburton &amp; Pearce, 1905) . [See Weigmann (1997a) for discussion of synonymies in this group.]. Notable traits include: the presence of four larval setae (including cʺ) on tibia I, with no additions; the absence of cʺ from larval tibia II, with no additions, for a final complement of three; the absence of several fundamental tarsal setae, including the primilateral pair (pl) from tarsus I, primiventral setae (pv) from tarsi I–III, and fastigial seta ftʹ from tarsus III. Of antelateral setae, only aʹ forms on tarsus IV. No accessory setae form on any tarsus. </p>
            <p>Illustrations of adult legs were provided by Weigmann (1997a); they are unlabelled, and slight variations in leg orientation make setal identifications somewhat challenging, but they accord well with the ontogenetic table. The absence of eustasic pair (pv) from tarsus I, as well as II–III, and the absence of any proximal accessory setae, conspicuously leaves the unpaired seta s as the most proximal seta in the ventral region of these tarsi. Eustasic pair (a) forms as usual on these tarsi, occupying a clearly lateral position, slightly higher than usual in oribatid mites and slightly distal to the level of s.</p>
            <p> For most other  Trhypochthoniellus species leg setation is unknown or analysed based only on adults. In  T. chilensis Ermilov &amp; Weigmann, 2015 and  T. malaconothriformis Ermilov et al., 2017 , the tarsal setation seems to differ from that of  T. longisetus in two ways. First, both species seem to form pair (pv) on tarsus I; their homology could only be confirmed with knowledge of early instars, but it seems likely they are (pv), since no proximal accessory setae are known in this genus. The second difference is that the partial regression of pair (a) on tarsus IV of  T. longisetus seems to extend also to the other tarsi in  T. chilensis and  T. malaconothriformis , such that only the abaxial (antiaxial) member of the pair is formed (aʺ on I/II, aʹ on III/IV). These authors misidentified the antelateral setae as accessory iteral setae (itʺ, itʹ), which do not develop on any known member of  Trhypochthoniidae ; antelateral setae can be unusually high in this genus, close to or even distal to setae tc. Tarsi I–III of  T. churincensis Ojeda et al., 2020 also lack pair (pv) and probably one antelateral seta; the latter point is equivocal, as their illustrations are difficult to interpret and they wrongly applied many setal notations (including it); tarsus IV is like that of all the other  Trhypochthoniellus species. The only other data we have comes from a past study of adult type specimens of  T. ramosus Hammer, 1982 (R.A.N., unpublished, 1996); it has leg setation identical to that of adult  T. longisetus except for lacking seta vʹ from trochanter III. Overall, the data allow the following generalizations  Trhypochthoniellus species lack the primiventral pair (pv) on tarsi II, III and in some species also on I; antelateral setae are present as a pair on tarsi I–III or only the abaxial seta forms; leg IV always forms pair (pv) and seta aʹ; no proximal accessory setae form on any tarsus. </p>
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	https://treatment.plazi.org/id/03AF87E16B533D574786FBD0FE1CA409	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B5C3D574786FD3CFAA5A5E9.text	03AF87E16B5C3D574786FD3CFAA5A5E9.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trhypochthonius Berlese 1904	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Leg setal ontogeny of  Trhypochthonius</p>
            <p> Appendix 3 presents the ontogeny of leg setiform organs in an unidentified species of  Trhypochthonius from South Africa. Notable traits include; the presence of four larval setae (including cʺ) on tibia I, with a final complement of five; the absence of cʺ from larval tibia II, with a final complement of five; the absence of several fundamental tarsal setae, including the primilateral pair (pl) from tarsus I, primiventral setae (pv) from tarsi II and III, and fastigial seta ftʹ from tarsus III. Antelateral (a) setae are not formed on tarsus IV. Regarding accessory setae, the iteral pair (it) are absent and the adult forms proximal seta l A ʹ on tarsus I and pair (v A) on tarsi I–IV. </p>
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	https://treatment.plazi.org/id/03AF87E16B5C3D574786FD3CFAA5A5E9	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
03AF87E16B5C3D544786FC1CFC09A79D.text	03AF87E16B5C3D544786FC1CFC09A79D.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trhypochthoniidae (Norton 1998)	<html xmlns:mods="http://www.loc.gov/mods/v3">
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            <p> Overview of leg setation in  Trhypochthoniidae</p>
            <p>With ontogeny known for at least one species in each genus, we propose the following as traits that could be added to a description of the family. (1) Primilateral setae absent from tarsus I (and all other tarsi). (2) Primiventral setae (pv) absent from tarsi II and III, present on tarsus IV, and with various states on tarsus I (usually present). (3) Antelateral setae (a) usually present on tarsi I–III (rarely the adaxial seta is absent), with various states on tarsus IV. (4) Seta ftʹ absent from both tarsi III and IV. (5) Iteral setae absent from all tarsi. (6) Proximal accessory setae present (usually) or absent; lateral setae usually present on I, absent from II-IV; ventral setae usually absent from I, present on II–IV. (7) Larval tibia I with four setae, including d, lʹ, vʹ and cʺ; larval tibia II with three, lacking cʺ.</p>
            <p> Loss of primilateral setae. Grandjean (1959) summarized the distribution of the eustasic primilateral setae in oribatid mites and noted that the typical pattern in  Nothrina (his Nothroidea) and Brachypylina (Circumdehiscentiae) is to have pair (pl) present on tarsus I but absent on the other tarsi. Various groups of Brachypylina have lost this pair, but among  Nothrina only  Trhypochthoniidae and  Malaconothridae lack them entirely. </p>
            <p> Loss of primiventral setae from tarsi II and III. The most interesting, and perhaps controversial, aspect of leg setation in this family relates to the diminished fundamental setation on tarsi II and III. Most uncertainty relates to what can be referred to as the ‘ventral quintet’: seta s and pairs (a) and (pv). When one or more of these setae are absent it is difficult to be certain which setae remain. Wauthy &amp; Fain (1991, with a contribution by J. Travé) explained the difficulty with regard to  Malaconothridae , where three of the quintet are lost from tarsi I–III. Their solution (like that of Knülle 1957) was that setae s and (a) were lost, leaving pair (pv). By contrast, Ermilov &amp; Rybalov (2023) believed s and (pv) were lost, leaving (a). But alternative possibilities exist, since these authors illustrated the ʺ seta (pvʺ or aʺ according to author) as lying on the ventral midline, in the usual position of s. Wauthy &amp; Fain (1991) explained the midline position of the purported pvʺ as the result of rotation (basculation) of the setal verticil. However, s is a very stable seta among oribatid mites and it seems no less likely that the remaining setae are s, pvʹ (or s, aʹ). </p>
            <p> Trhypochthoniidae have lost two or three of the setal quintet. In an early, comparative application of his chaetotaxic model for leg setae, Grandjean (1941a) noted that larval tarsus II of  Trhypochthonius tectorum lacks one pair of setae that occur in related families (it is also true of III, but this tarsus was not discussed); he was uncertain but believed that the missing pair was (pv). We agree with his assessment and believe all members of the family share this loss on tarsi II and III. </p>
            <p> Overall, the loss of primiventral setae seems to be quite rare. To our knowledge, aside from  Trhypochthoniidae — and  Malaconothridae in the above-noted opinion of Ermilov &amp; Rybalov (2023) —the only losses of (pv) reported in the literature relate to: their partial or complete regression in a small group of protoplophoroid Enarthronota (Grandjean 1946c; Norton et al. 1983); their absence from tarsus II (only) in  Nehypochthoniidae (Norton &amp; Metz 1980) ; their reported absence from all legs of a species of  Parapirnodus (  Scheloribatidae ; Behan-Pelletier et al. 2002); and their absence from tarsus IV of  Epilohmannia cylindrica as interpreted by Grandjean (1946b). </p>
            <p> In  Trhypochthoniidae , the key to identifying the missing setae as pair (pv) lies in comparing the spatial relationships of the quintet— s, (a), (pv)—on tarsus I of the larva, where they typically are all present, to those on tarsi II and III, where one pair is absent. It is perhaps most clear in  Archegozetes longisetosus . On larval tarsus I setae (pv) have their typical position—on the ventral face and distinctly proximal to s —while setae (a) also have their typical position, low on the lateral face and slightly distal to s. The same features of s and pair (a) are true on larval tarsi II and III, but no ventral setae are proximal to s, so clearly it is pair (pv) that are absent in this species. It is also clear in  Trhypochthoniellus longisetus , where on larval tarsi I–III pair (a) are at the level of s or slightly distal to it; since there are no setae proximal to s, pair (pv) are undoubtedly absent. The other trhypochthoniid genera differ in that s is slightly distal to pair (a) on larval tarsus I, with (pv) placed normally, proximal to these three setae; on tarsi II-III, the relationship of s and (a) is similar to that on I, but no setae are proximal to (a). On tarsus I pair (pv) have a slightly but distinctly more ventral position than do (a), and in the adult (pv) align well with the ventral accessory setae, whereas pair (a) do not. </p>
            <p> Loss of ftʹ from tarsus III. Grandjean (1941a, p. 39) noted the deficiency of one fastigial seta on tarsus III in the three genera of  Trhypochthoniidae he had studied (  Archegozetes ,  Trhypochthonius and  Trhypochthoniellus ), and it appears to be a feature of the entire family. While he did not identify the specific missing seta (perhaps because the remaining seta is close to the dorsal midline), clearly it is ftʹ that is absent. 8 This mirrors the common and nearly ubiquitous situation on tarsus IV of oribatid mites (Grandjean 1946b). We know of no other  Nothrina that have lost ftʹ from tarsus III, but the loss occurs in some Enarthronota and Ptyctima. </p>
            <p> Loss of iteral setae. Grandjean(1961, 1964a) reviewed the distribution and ontogeny of the accessory, amphistasic iteral pair (it) among oribatid mites. The vast majority possess iteral setae on one or more legs, but their complete absence is not rare. Since they always are post-larval, their disappearance is easily explained as paedomorphic—i.e., retention of the larval state. Among  Nothrina, Grandjean indicated their absence from those  Malaconothridae and  Trhypochthoniidae known to him, and this pattern remains true after the subsequent addition of much more data. He also considered iteral setae absent from  Nothridae , but he had studied only species of  Nothrus ; iteral setae have been reported in the more plesiomorphic genus  Novonothrus (Casanueva &amp; Norton 1997, 1998). 9 </p>
            <p>Setal ontogeny of trochanter III</p>
            <p> Among  Oribatida , trochanter III most often bears two setae, vʹ and lʹ. The instars in which these setae first appear are usually constant within a species but are quite varied among species. Each may appear in any instar except the larva, their sequence can be reversed, and in rare cases one or both never appear at all (see references on leg setal analyses in Norton &amp; Ermilov 2014, 2024). </p>
            <p> What seems to be the ancestral oribatid mite pattern is for v ʹ to form in the PN and lʹ in the DN. This is the principal pattern found in Palaeosomata, Enarthronota, Parhyposomata and some Mixonomata, as well as the outgroup Endeostigmata (e.g.,  Petralycus ; Grandjean 1943). The pattern is known from all families of  Nothrina except  Crotoniidae but in each family there are other variants.Among Brachypylina it is the typical (but not exclusive) pattern in Neoliodoidea, Damaeoidea and Ameroidea and is found in some Plateremaeoidea and Cepheusoidea. But most brachypylines, including all the poronotic superfamilies, have different (presumably derived) patterns. </p>
            <p> Among  Trhypochthoniidae , the ancestral pattern is found in  Archegozetes and  Trhypochthonius , but three variant ontogenies are known. In  Mainothrus and  Allonothrus seta vʹ is delayed one instar, so that both setae form in the DN. In  Afronothrus and  Trhypochthoniellus vʹ is delayed further, to the TN, thereby reversing the ancestral sequence. 10  Mucronothrus presents a third variant, in which lʹ is PNal and vʹ DNal, also reversing the ancestral order; if our concept of the ancestral pattern is correct, this would represent a derived ontogenetic acceleration of lʹ. It is rare for lʹ to form in the PN but both setae are PNal in  Perlohmannia dissimilus (Grandjean 1958) and  Eulohmanniidae species (Norton &amp; Ermilov 2022). Seta lʹ is not known to form earlier than the DN in more basal groups, such as Enarthronota and Parhyposomata. </p>
            <p> 8 The identity of ftʺ is supported by the anomalous occurrence of both fastigial setae on one leg of one specimens of  Mucronothrus willmanni (Norton et al. 1996) . This rare loss of suppression allowed ftʹ to form in a position typical of that seta in other nothrine families. </p>
            <p>9 The presence of iteral setae seems correct, but various other aspects of leg setation proposed in this study, including the implied amphistasis of primilateral and primiventral setae, need reinvestigation.</p>
            <p> 10 Seta vʹ never forms in  Trhypochthoniellus ramosus (see above), which we consider the culmination of a transformation series of sequential delays. </p>
            <p>Setal priorities on genua III and IV</p>
            <p>In a special study of the priority—i.e., resistance to regressive loss (Grandjean 1941b)—of setae on genua of Acariformes, Grandjean (1942a) determined that ancestrally the fundamental chaetome of genua III and IV are identical. In particular, setae d and lʹ are both present when the legs first form. This was evident from studying Endeostigmata, where it seems to be the rule (Grandjean 1942b, p.105). From studying the ontogeny of a wide range of oribatid mite taxa, Grandjean (1942a, p. 50) generalized that the usual priority of setae on genua III and IV in this group was (in decreasing order) d, lʹ, vʹ, vʺ, lʺ. Over evolutionary time, setal regressions (ontogenetic delays or losses) acting on these genua would first affect the end of the list, and then move toward the beginning.</p>
            <p> With much more data available now (see leg setal analysis listings in Norton &amp; Ermilov 2014, 2024), the priorities largely still hold for genu III— particularly with regard to lʹ and vʹ —even though there is great variation in the chaetome and the specific ontogeny. We have noted a couple exceptions. In  Nanhermannia coronata seta lʹ is lost while v ʹ remains (Seniczak &amp; Seniczak 2023). More striking, in some  Oribatulidae —e.g.  Zygoribatula exilis and  Phauloppia nemoralis —it is vʹ that is fundamental, with lʹ lost (Ermilov &amp; Kolesnikov 2012; Ermilov et al. 2015). </p>
            <p> By contrast, genu IV, which usually forms no setae until the DN, is less stable in this regard. Grandjean (op. cit.) noted several exceptions to the ancestral priority on genu IV, including one genus in each of three major groups, in which v ʹ forms in an earlier instar than lʹ— Palaeosomata (  Aphelacarus ), Parhyposomata (  Parhypochthonius ) and  Nothrina (  Nanhermannia ) 11 — but now we see it is more widespread. This derived, inverted priority is found on genu IV of the parhyposomatan genera  Elliptochthonius and  Gehypochthonius and the mixonomatan  Nehypochthonius , in which lʹ is lost but vʹ remains. In  Collohmannia lʹ is variable and can form after both vʹ and vʺ. While most Brachypylina retain the ancestral priority of lʹ, vʹ on genu IV, in  Eremaeidae and  Megeremaeidae vʹ forms while lʹ is lost, and vʹ can even be fundamental. </p>
            <p> Among  Nothrina ,  Trhypochthoniidae are unique in showing a consistent pattern of reversed priority of lʹ and vʹ on genu IV. 12 Either vʹ precedes lʹ during ontogeny (  Afronothrus ,  Archegozetes ,  Mucronothrus ,  Trhypochthonius ) or vʹ forms while lʹ is lost (  Mainothrus ,  Trhypochthoniellus ). In the most striking example, vʹ even takes the place of lʹ as being fundamental on genu IV of  Archegozetes . Only in  Allonothrus is this reversal equivocal, since both lʹ and vʹ form together in the TN. </p>
            <p>Homology and analogy in the chaetotaxy of tibiae I and II</p>
            <p>Grandjean (1940a, 1940b, 1954b) demonstrated that tibiae I and II of adult oribatid mites have an ancestral setation forming a whorl of seven setae. Originally proposed as unpaired d, and pairs (ls), (li), and (st), these notations were simplified to d, (l), (c), and (v), when homologies with the more common vertical of five setae— entirely lacking (c)—were established (Grandjean 1954b). 13 Outside of Palaeosomata, cʹ does not occur and the maximum (except for neotrichous taxa) is an adult chaetome of six: d, (l), (v), cʺ.</p>
            <p> For any member of  Nothrina with known ontogeny, the presence of six setae on adult tibia I or II indicates that the larva has four setae: d, lʹ, vʹ, and cʺ, with lʺ and v ʺ always being accessory, i.e., added during ontogeny (Fig. 10; square box). This is the case for tibia I of  Allonothrus , for example (Appendix 1). However, cʺ can be present in the larva even if the adult chaetome is only four or five setae: it only means that one or both of the possible accessory setae fail to form, as occurs in all other genera of  Trhypochthoniidae (Fig. 10). On tibia II of  Trhypochthoniidae , cʺ never forms, but the accessory setae (lʺ, vʺ) show the same range of states as they do on tibia I. Under such circumstances, a species may have the same number of setae on tibiae I and II while their exact compositions differ (e.g.,  Trhypochthonius ,  Mucronothrus ). </p>
            <p> 11 Grandjean (1942a) did not mention the species of  Nanhermannia he studied. This inverted priority occurs in  N. coronata , but not  N. sellnicki (Seniczak &amp; Seniczak 2023; Seniczak A. et al. 2023). </p>
            <p> 12 Grandjean (1942a, p. 48) considered the TNal seta on genu IV of  Trhypochthonius to be lʹ, but we think this is incorrect. The TNal seta has a markedly ventral position, aligned with setae evʹ of the femur and vʹ of the tibia and must instead be vʹ. In the adult, seta lʹ appears in its normal position, on the anterior (ʹ) face, midway between d and vʹ. Grandjean (op. cit.) also was uncertain of the identity (lʹ vs. vʹ) of the anterior seta that appears in the TN of  Trhypochthoniellus longisetus setosus , but as in  Trhypochthonius it is aligned with the ventral setae of femur and tibia, and there seems to be little doubt that it is vʹ; no seta is added in the adult to fill the large space between it and dorsal seta d. </p>
            <p>13 Despite this change, the original notations, particularly liʺ, have remained sporadically in use.</p>
            <p>Like many tarsal setae, cʺ on tibiae I and II is both fundamental and eustasic: if not present in the larva, it never forms during ontogeny. Because of its position in the lower third of the posterior face, Grandjean (1940a; 1941b) recognized that cʺ (= liʺ) is easily mistaken for accessory seta lʺ or vʺ, if one or both of these latter setae do not form. Therefore, with regard to homology, a tibia I chaetome of five does not directly translate to a standard verticil of five— d, (l), (v). He gave examples of chaetomes of five in which cʺ appeared to ‘imitate’ lʺ and others where it masqueraded as vʺ. If notations based on homology are the goal, then the literature is replete with errors or inconsistencies. Below, we use examples to examine these issues in a larger taxonomic context, attempting to identify general evolutionary changes to the chaetome of tibiae I and II.</p>
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	https://treatment.plazi.org/id/03AF87E16B5C3D544786FC1CFC09A79D	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Norton, Roy A.;Ermilov, Sergey G.	Norton, Roy A., Ermilov, Sergey G. (2024): Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida). Zootaxa 5556 (1): 144-199, DOI: 10.11646/zootaxa.5556.1.13, URL: https://doi.org/10.11646/zootaxa.5556.1.13
