Eulohmannia bifurcata Fujikawa, 2014

Norton K, Roy A. & ErmilovK, Sergey G., 2022, Paedomorphosis and sexuality in Eulohmanniidae (Acari, Oribatida): surprising diversity in a relictual family of oribatid mites, Acarologia 62 (4), pp. 989-1069 : 1023-1031

Eulohmannia bifurcata Fujikawa, 2014 , new status

Although it was proposed as a subspecies Eulohmannia ( ribagai bifurcata Fujikawa, 2014 ),

we believe there are sufficient reasons to distinguish this mite from E. ribagai and elevate it ;

to species rank. It is known only from type specimens, which were derived from two separate collections in the east-central region of Honshu Island, Japan. One of us (R.A.N.) borrowed the five specimens —all female and all slide-mounted—from the National Museum of Natural History (Tokyo). The holotype (13642; Fig. 16G ) from Tochigi Prefecture is strongly crushed (probably intentionally) and used as the source for Fujikawa’s Figs. 3-5 ; the captions to these figures wrongly refer to it as a paratype. The medium (unidentified) is deteriorating somewhat, and fibers are embedded, one of which transects the specimen. The four paratypes from Fukushima Prefecture are whole-mounted, apparently in a resin-based medium; there are two each on slides 13643 and 13644, mixed in a slurry with about 20 specimens of other mite species. Below, we use arbitrary designations (A, B) for the paratypes on each slide: 13643A ( Fig. 17A ) is a ventrolateral mount, not illustrated by Fujikawa but exhibiting some features that are difficult to see on other specimens; 13643B is a dorsal mount shown in her Fig. 2A ; 13644A ( Fig. 17E ) is a ventral mount shown in her Fig. 2B ; 13644B is a dorsal mount, not illustrated. They are not well cleared. Her measurements (length 571-629) suggest that E. bifurcata is slightly smaller than E. ribagai , but the paratypes are contracted; using our method (summing protero- and hysterosoma), they are 630-670.

Differences with E. ribagai — Fujikawa identified traits that seemed to clearly distinguish E. bifurcata from E. ribagai ; some were highly relevant to classification and phylogenetic inference, but they were not discussed in this light. The most surprising of these—the purported presence of supracoxal seta eII— could have been perceived as an atavistic return of an ancient trait. Several others—including opisthosomal glands and chelicerae having Trägårdh’s organ and seta cha —would have been unique plesiomorphies within the family. As discussed below, we consider these traits and several other to reflect errors in observation or interpretation. However, differences in six traits seem sufficient to recognize this mite as a distinct species. States in E. ribagai (given in parentheses) are based on our studied material from all provenances. Leg setation does not differ from that of adult E. ribagai , including the distribution of eupathidia (see Tables 3-5).

(1) Epimere III has five pairs of setae (vs. four pairs). This is consistent in all five type specimens. Setae 3a, 3b, 3c, and 3d are similar and rather short, but the most lateral 3 (e)

is long and conspicuous (resembling 3d of E. ribagai ). Fujikawa seems to have confused

3e with the similarly-sized notogastral seta c 3. She omitted 3e from the ventral figure (her Fig. 2D ) and in the dorsal figure (her Fig. 2A ) 3e is mistakenly labeled ‘ c 3 ’ on the left side, where the actual c 3 is not drawn—it curves artificially toward the sejugal articulation and is made inconspicuous by following the notogastral margin in dorsal view. On the neotrichous hysterosomal venter, the setation of epimere IV is inseparable from that of the aggenital region, as in E. ribagai .

(2) A small vertical ridge r (1) posterior to leg I, distinct in both lateral ( Figs 16H , 17D ) and dorsoventral views ( Fig. 17F ), extends ventrad from supracoxal seta eI to the leg insertion

(vs. ridge absent; cf. our Fig. 8C ).

(3) The posterior arms of the aggenital sclerite encompassing the genital aperture ( Fig. 18A ) are broadly rounded posteriorly (vs. distinctly tapered posteriorly; our Fig. 9A ; Grandjean 1956b, his Fig. 1A ). Fujikawa illustrated this region in three figures, but none is entirely accurate. Her Fig. 2B shows the arms merging behind the genital aperture of a paratype, but they do not; details in this region easily can be misinterpreted due to the state of contraction and cuticular folding. In her Fig. 4C the adanal and anal plates of the holotype are accurately drawn—what she considers the ‘anterior anal locking-piece’ is the preanal apodeme—but the aggenital region is wrongly depicted. Her Fig. 4D shows an intact aggenital region in the holotype ; the broad arms are drawn correctly but the small, separate sclerites are omitted, and the lines behind the aperture are not interpretable. This latter figure must have been made before the holotype was strongly crushed, since the region is now split longitudinally. The holotype is dorsally mounted, but with DIC illumination the small ‘island-like’ sclerite posterior to each broad arm is visible by transparency ( Fig. 18A ).

(4) Femur IV is about 1.5-1.7 times the length of trochanter IV (vs. 1.3-1.4 times).

(5) Seta acm of the palp tarsus is a normal seta in the adult (vs. eupathidial; cf. Figs 16M , 11G ). Since acm usually transforms to a eupathidium early in ontogeny (the protonymph in E. ribagai ) we consider this a neotenic trait. However, the palp could be studied closely only on the holotype, so other examples are needed to confirm this difference.

(6) Distal leg segments (genu-tarsus) are noticeably sculptured (vs. smooth or with only weak undulations). Fujikawa (her Fig. 5A ) identified a small boss distal to tarsus I seta tc ʹ that does not exist in E. ribagai , but other sculpturing is more extensive and conspicuous. The ventrodistal cuticle of genu and tibia of legs I and II is strongly undulating ( Fig. 18B, C ) and the distal three segments of all legs have an oblique declivity on the adaxial face ( Fig. 18D , arrows) that emphasizes the basal stalk and gives the impression of a rudimentary, weakly-defined retrotectum.

Additionally, setae on the dorsum of E. bifurcata , particularly prodorsal seta le and notogastral setae, are relatively longer than in most E. ribagai . In E. bifurcata , le is slightly longer than the mutual distance of the paired alveoli, whereas in our studied material of E. ribagai they are distinctly shorter than their mutual distance, often only half that length. However, some literature figures of E. ribagai show le equal to that distance (e.g., Balogh 1943 ; Kunst 1971). The notogastral setae of E. bifurcata are relatively long, reaching the insertion of nearby setae, or nearly so. In E. ribagai they are generally shorter, typically reaching only about halfway to nearby setal insertions (e.g., Lebrun and Wauthy 1980; Weigmann 2006), but in specimens from New York ( Fig. 2C ) and Ukraine ( Sergienko 1994) they are intermediate in length.

Equivocal or incorrect distinctions — Fujikawa’s Table 1 includes seven traits that she believed distinguished the two taxa. Two of these are variable traits of limited value. She characterized the genital setation of E. bifurcata as 7-8 pairs and that of E. ribagai as 8-10. However, the latter species can have as few as seven (R12). While not an absolute difference, E. ribagai usually has nine pairs, compared to eight on those genital plates of E. bifurcata that are most clearly visible. She also characterized supracoxal seta eI as having minute distal tines in E. ribagai , but in some populations they are as long as in E. bifurcata ( Fig. 8 ; R9). A third trait, epimeral setation, was incorrectly characterized for both species, though they do in fact differ (see above, #1). The other four purported differences result, in our opinion, from mistakes in observation or interpretation, as explained below. In each case the relevant specimens were examined at magnifications up to 1500×, under all available types of illumination.

Notogastral setae. Fujikawa indicated that E. ribagai has 16 pairs of notogastral setae, while E. bifurcata could have either 15 or 16. We view both statements as incorrect. There are consistently 15 pairs in adult E. ribagai (see above, and R5). Her suggestion of variation in E. bifurcata relates to the presence or absence of a seta labeled h ‘ 3 ’ in her Fig. 2D , which appears to be inserted near her h ‘ 2 ’ (our h 3), lateral to the lyrifissure that she incorrectly labeled ih ‘’ (see below). She indicated in the text (p. 8) that h ‘ 3 ’ was absent from only one side of one specimen, though it is absent from one side of both her Figs. 2A (13643B) and 2D (13644A). We could closely examine the two illustrated regions where h ‘ 3 ’ was shown, and each specimen had only one seta in this vicinity: her ‘ h 2 ’ (our h 3 ; cf. Fig. 17 G, H ). The same is true of paratype 13644B

(not illustrated). Paratype 13643A could be studied only on one side, but it clearly shows the presence of a single h -seta in this region ( Fig. 17B ). This region of the crushed holotype could be studied closely on each side, and there is a single seta. It is unequivocal that the notogastral setation of E. bifurcata comprises 15 pairs, identical to that of E. ribagai .

Opisthonotal glands. Fujikawa’s Fig. 2A shows a small circle closely posterior to notogastral seta ‘ h 1 ’ (our h 2), which she labeled gla, the opisthonotal gland opening. This would be a unique position for gla, well posterior of its usual position somewhere near seta f 2. Using all available lighting at 1500× we examined the dorsally mounted paratype (13643B) from which her Fig. 2A was drawn and found no gland aperture. On the left side of the paratype it seems clear that she drew a small bead-like structure (in our Fig. 17H ); this may be some on artifact of the mounting process or preservation, but it is subsurface and certainly not gla. We could not identify a structure that would have suggested a gland opening on the right side of

13643B, or on either side of the other dorsally mounted paratype (13644B).

Trägårdh’s organ. Fujikawa (her Fig. 4E , drawn inverted) illustrated a well-developed

Trägårdh’s organ on a chelicera of the holotype, but it appears on the abaxial (= antiaxial) face,

as shown by the presence of seta chb ; this is an impossible position for Trägårdh’s organ, which extends from the body wall on the inner (adaxial, paraxial) face of the chelicera (e.g., Hammen

1968). Both chelicerae of the crushed holotype have their abaxial faces up ( Fig. 16J ), and the adaxial face is visible by transparency; we see no structure on either side of either chelicera that could be identified as Trägårdh’s organ. No views were possible on the intact paratypes.

Supracoxal seta eII. Fujikawa indicated that E. bifurcata differed in having three pairs of supracoxal setae (e, eI, eII) compared to only eI in E. ribagai . Clearly, she was mistaken about ‘ e ’, the postpalpal seta (ep), since it always exists in E. ribagai (e.g., our Fig. 3D ).

Seta eII indeed does not exist in E. ribagai , but she seemed unaware of the rarity of this metameric homologue of eI. A few taxa of Prostigmata, including Anystidae , Bdellidae and some Parasitengona, as well as Opilioacarida ( Hammen 1980 ; Kethley 1990), possess eII and it can be considered plesiomorphic in those groups. But to our knowledge it is not known to occur in any endeostigmatid or sarcoptiform mite ( Grandjean 1939a, 1954a).

Fujikawa included eII in two figures but showed it at two different locations. Her Fig. 2D

(ventral view, paratype 13644A) shows the seta bilaterally, on the projecting posterolateral corner of epimere II and distinctly posterior to trochanter II. But when the surface is in focus clearly there is no seta here, on either side ( Fig. 17F ). We believe she misinterpreted a gland duct as a setal alveolus: the duct of the posterior podocephalic gland ( Grandjean 1939b, his Fig.

2; gl.m) is round in cross section (d.gp ; Fig. 17F insert) and is found in that exact location. The other figure is her Fig. 4A , which is an inverted lateral view (ventral at top) showing details of the podocephalic region on the left side of the crushed holotype (13642). The cuticle in the relevant posterior region of the canal is broken, but her illustration of this region—which seems unchanged since 2014—wrongly suggests that the cracks are internal structures (cf. Fig.

16H). In this figure, she drew eII dorsal to trochanter II—between it and the podocephalic canal

(cpc)—but we found no seta there, only a minute, pale mark of uncertain nature (* in our Fig.

16H). Paratype 13643A provides a clear and intact view of this region: seta eI and all three gland openings (cf. Hammen 1982, his Fig. 15D ) are clearly visible, but there is no seta eII, or any other structure at its purported location.

Other notable errors — Four other traits described for E. bifurcata differ conspicuously from those of E. ribagai , but they were not included in her differentiation table.

Notogastral lyrifissures. According to Fujikawa’s illustrations and interpretations, E.

bifurcata would clearly differ from E. ribagai in the distribution of three typical notogastral lyrifissures: ip, ih, and ips. In adult E. ribagai ( Grandjean 1956b ; Lebrun and Wauthy 1981)

—as well as other species discussed below— the lyrifissures have consistent locations similar to those in many other oribatid mites. Lyrifissure ia is posterior to seta c 2 ; im is posterior to

d 2 ; ip is either posteromedial or lateroventral to f 2 ; and both ih and ips lie near the notogastral margin, visible only in lateral or ventral aspect. Fujikawa (2014) did not include lyrifissures in her illustrations of E. ribagai , but five were indicated for E. bifurcata (her Fig. 2A, C ). She showed ia and im in their usual places and a third pair posteromedial to f 2 — the latter is labeled ih but clearly is ip, which has been associated with segment F ( Grandjean 1939d). Therefore,

the anterior three pairs are distributed exactly as in E. ribagai . Of the remaining two, one pair purportedly lies on the posterior contour of the notogaster in dorsal view (her Fig. 2A , wrongly labeled ip), medial to setal pair ps 1. We studied this region of paratype 13643B, from which the figure was made, and found no lyrifissure there: on the left side there is a small linear artifact

(** in Fig. 17H ); on the right side the notogaster is damaged (cracks not shown in her figure)

and nothing resembling a lyrifissure could be found. The remaining lyrifissure purportedly lies between setae ‘ h 2 ’ (our h 3) and ps 3 and is labeled ips in her Fig. 2B . Her figure was drawn from paratype 13644A, but we found no lyrifissure on either side at that location (cf. Fig. 17G ).

Since both ih and ips are theoretically located at the end of their respective setal row ( Grandjean 1939d), the positions she ascribed to either of these lyrifissures would be incongruent. In fact, ih and ips of E. bifurcata have the same locations as in E. ribagai , lying in tandem along the border of the notogaster, anterior to seta ps 3. They can be seen in paratype 13643A, which shows this region clearly ( Fig. 17C ) and also in the crushed holotype ( Fig. 18A ).

Cheliceral setae cha. Fujikawa did not discuss the setation of the chelicera in E. bifurcata ,

but her Fig. 4E of the holotype shows two setae. Seta chb inserts distally on the abaxial face of the fixed cheliceral digit, as in all instars of E. ribagai (e.g., Fig. 10H ). Seta cha, which does not exist in any instar of E. ribagai , is drawn as a small, barbed seta inserted low on the abaxial face, such that the axis of rotation for the movable digit would precisely pass through the purported setal alveolus. This would be a unique location: seta cha exists in most oribatid mites, but it is inserted either on the dorsal midline or high on the adaxial face. We could not find cha on either chelicera of the holotype and believe that Fujikawa misinterpreted the cotyloid fossa of the movable digit cot (, Fig 16J ; see Grandjean 1947, his Fig. 2B ) as a setal alveolus. We believe that she misinterpreted the edge of the thin articulating cuticle ( Fig. 16J ,

insert) as a seta, but we cannot explain the illustration of fine barbs in her Fig. 4E .

Rutellar brush. The rutellum of E. ribagai bears two independent brushes on its dorsal face,

one shorter than the other and differently oriented (e.g., Fig. 10D ). In her Fig. 3E , taken from the holotype, Fujikawa illustrated the rutellum of E. bifurcata as having a single brush, but there are two ( Fig. 16K ), formed as in E. ribagai .

Empodial vestige. Fujikawa described the pretarsus of E. bifurcata as ‘homobidactyl’ and illustrated this for tarsus I of the holotype (her Fig. 5A ), where no vestige of an empodial claw was shown. However, such a vestige does exist on all legs that are oriented for favorable viewing (e.g., Fig. 16I, L ). It has the same tandem, bidentate form as E in. ribagai (cf. 15B).

Another possible species from Japan?

Suzuki (1979) studied a protonymph from Japan that he thought represented E. ribagai but that differs markedly from the nymphs studied and described by us. His Fig. 2 shows two large, distinct sclerites on the gastronotum, and these, as well as the prodorsum, are punctate or have small, well-spaced foveolation, rather than the general reticulation found in all instars of E. ribagai . Otherwise, the facies are like those of E. ribagai nymphs, and the rostrum has a similar mucro and adjacent notches.

Suzuki referred to Aoki’s (1975) drawing of E. ribagai to represent the adult. However,

Aoki (his Figs 1 , 2 ) illustrated a mite with lamellar setae and setae of the neotrichous ventral plate that are significantly longer than in all E. ribagai studied by us. Aoki clearly illustrated a complete encompassing of the genital aperture by the aggenital region of the ventral plate; this does not occur in E. ribagai though some published illustrations have been wrong or vague about this detail. No cuticular reticulation was shown or described by Aoki, but this pattern can be indistinct depending on preparation and observation methods—e.g., it has been omitted from several figures of E. ribagai (e.g., Kunst 1971 ; Weigmann 2006). Enough discrepancy exists to warrant reexamining Japanese mites ascribed to E. ribagai and to investigate their juveniles.

Two undescribed species from Asia

A large sexual species from Russia — We believe a population referred to herein as Eulohmannia . sp. A ( Fig. 18E ), from Aborigen, represents an undescribed species closely related to E. ribagai . Examined material is from the subarctic Kolyma Highlands of Magadan Oblast, Russian Far East. Like populations of E. ribagai from the Pacific Northwest, this species almost certainly is sexual, and it inhabits an area with a complex glacial history ( Bar and Clark 2012). We studied a series of prepared slides from the CNC, with the following data: Aborigen, southern parts of Bolshoi Annachag Mountain, vii-1979, A. Fjellberg col. (4 males,

3 females); same, along Aufeis River, 25-vii-1979, A. Fjellberg col. (1 female); Aborigen

Alpine Study Area, Saddle site, 23-vii-1979, V. Behan col. (5 females, 4 males, 1 La, 1 Pn,

2 Dn, 2 Tn); same, Aborigen Transect T1S4, 25-vii-1979, V. Behan col. (1 female). While having the same body facies as E. ribagai , and a similar pretarsal empodium, these mites differ in significant ways. First, with an average total length of 800 µm (n = 19) adults are distinctly larger (R1). The range (718-854) overlaps the values for E. ribagai slightly, but the smallest of the Aborigen mites are male (718-776). Leg IV has a proportionally smaller trochanter (femur

~2× length of trochanter, vs 1.3-1.4 in E. ribagai ; cf. Figs 2A , 18E ), trochanter III bears three setae (vs. two), and the setation of tarsus I differs in several ways, particularly with regard to setae of the c -row and eupathidia (R20, R21). With the two larger samples being nearly half males ( Fig. 18G ), the mite is probably sexual. By contrast, our Eulohmannia material from Khabarovsk (also Russian Far East, but in the temperate south) is typical of E. ribagai in all traits, including size (650-756 µm, n = 9), leg traits, and the absence of males.

A paedomorphic species from Kashmir — We have studied four adults from a population in the Kashmir Valley (the Indian-administered union territory of Jammu and Kashmir), referred to herein as Eulohmannia sp. B , that certainly represent an undescribed species. Collection data are: Kashmir, Dachigam National Forest (near Srinagar), 20-viii-1986, R.A. Norton col., from litter at base of elm tree ( Ulmus wallachiana ) in mixed forest. The body ( Fig. 17D ; ~

680 long) appears almost indistinguishable from that of adult E. ribagai , except for lacking the notches lateral to the medial rostral mucro. But all specimens have monodactylous leg pretarsi. The fully developed empodial claw has a strong spine-like process ( Fig. 18I ), like that E of. ribagai juveniles (cf. Fig. 15A ). Leg setation has some juvenile attributes also (R20, R21)

but there is no doubt these are adults as the ovipositor is distinct in each, and one has a fully developed egg ( Fig. 18H ). This is a clear example of neoteny, leading to paedomorphosis.

Equivocal or misplaced species

Gehypochthonius antonii Lombardini, 1962 — After its original description, based on material from Italy, this species seems not to have been mentioned again in the literature for three decades. Bernini et al. (1995) pointed out this oversight and noted that type material does not exist, but they did not discuss its possible identity. Subías (2004) listed G. antonii as a species inquirendum but in a recent update ( Subías 2022) he included it in Eulohmannia , without discussion. Based on Lombardini’s original description and figures, traits G of. antonii that are consistent with those of Eulohmannia (see below) include the following: (1) a facies described as slender (though not markedly so, based on his Fig. 1 ); (2) a prodorsum with an apparent posterior constriction (cervical collar) having longitudinal ridges on its ventral face; (3) a yellow coloration; (4) a strongly pectinate bothridial seta; (5) a lack of borders or apodemes associated with epimeres III and IV; (6) genital valves that are displaced far posteriorly; (7) a subterminal anal aperture; (8) an apparent parabolic scissure passing posterior to the genital valves and running toward the insertion of leg IV; (9) bidactylous pretarsi; and (10) a four-segmented palp. Collectively, this is a substantial set of traits that can be found in no known oribatid mite other than Eulohmannia , and the size is consistent with that of E. ribagai adults. But several other traits are incongruent with Eulohmanniidae . These include: (11) a hysterosomal dorsum with two transverse scissures (‘sutures’); (12) three pairs of setae on epimeres III, IV; (13) only three pairs of genital setae; (14) only two pairs of distinct, relatively large aggenital setae, i.e., without an aggenital neotrichy of numerous small setae; (15) only three pairs each of anal and adanal setae; and (16) cheliceral digits that are, proportionally, strikingly large. Traits 11-16 cast doubts about the classification of this mite Eulohmannia in. Add to this the fact that Eulohmannia was well-known as a distinctive genus in 1962, having been included and illustrated in all general treatments of oribatid mites (e.g., Sellnick 1928 ; Willmann 1931 ; Baker and Wharton 1952 ; Balogh 1961) and it seems unlikely that Lombardini would not have recognized the genus. In this light, and in the absence of type material, it seems most reasonable to continue listing Gehypochthonius antonii as a species inquirendum. Eulohmannia skrjabini Bashkirova, 1958 — The name of this mite, collected from southeastern Russia, was considered a junior synonym of Epilohmannia cylindrica ( Berlese,

1905) ( Epilohmanniidae ) by Bulanova-Zachvatkina (1975) ; probably it was a new proposal, though she gave no such indication. This synonymy almost certainly is incorrect, though it has been maintained in various reviews and checklists, such as Marshall et al. (1987), Panʹkov et al. (1997), Ryabinin and Panʹkov (2002) and, most recently, Behan-Pelletier and Lindo (2019). Bashkirova’s (1958) illustration (her Fig. 1 ) quite clearly shows the distinctive morphology of the family Perlohmanniidae . Rafalski (1966) thought it might be a junior synonym of Perlohmannia dissimilis Hewitt, 1908 ; Balogh and Mahunka (1983) treated it as a species inquirendum in Perlohmannia ; and it was recombined to Perlohmannia (Perlohmannia) skrjabini ( Bashkirova, 1958) by Subías (2004). In a recent overview of Perlohmanniidae, Ayyildiz et al. (2016) recombined the name to Hololohmannia skrjabini ( Bashkirova, 1958) ,

but it remains known only from the poor original description and was considered species a inquirendum by Subías (2022).

Figures

Figure 1 Eulohmannia ribagai(Berlese): A – larva, lateral view, epi-illumination; B – tritonymph, same; C – living adult, stereomicroscope (arrow to cervical collar); D – gravid female, with single egg (provenance uncertain, photo D.E. Walter); E – tritonymph, lateral view of gastronotum contour, with epicuticle separated by clearing; F – same, closeup optical section in polarized light; G – adult, notogastral cuticle at edge of sagittal section; H – tritonymph, right gastronotic setaec1, c2 and lyrifissureia (lower left insert = im from adult, right =im from deutonymph, showing canal). Scale bars 100 µm (A-D); 20 µm (E); 10 µm (H); 2 µm (F, G).

Figure 2 Eulohmannia ribagai(Berlese), adult, SEM images: A – lateral view; B – closeup of posterior proterosoma; C – dorsal view; D – frontal view (black arrow to narrow solid rostral rim); E – sejugal region, dorsal view. Scale bars 100 µm (A, C); 20 µm (B, D, E).

Figure 3 Eulohmannia ribagai(Berlese), larva (appendages incompletely shown): A – dorsal view B – posterior view of hysterosoma; C – ventral view; D – lateral view. Scale bar 100 µm.

Figure 4 Eulohmannia ribagai(Berlese), nymphs (appendages incompletely shown): A – protonymph, ventral view (prodorsum incomplete); B – deutonymph, ventral view of hysterosoma; C – tritonymph, dorsal view; D – tritonymph, ventral view; E – tritonymph, partial dorsal view of gastronotum showing artifactual transverse crease (see text, R3). Scale bars 100 µm: A, B to same scale, C-E to same scale.

Figure 5 Eulohmannia ribagai(Berlese): A – larval bothridium, dorsomedial view (only one of two saccules visible); B – deutonymph, bothridial saccules; C – adult, bothridium, dorsomedial view; D – adult, rostral tectum, sagittal view; E –sejugal articulation of extended specimen, dorsal midline (sagittal section), anterior to right; F – same, but contracted specimen; G – as in E, but ventral midline; H – bothridial region, dorsolateral view. Scale bars 10 µm (H); 5 µm (A-G).

Figure 8 Eulohmannia ribagai(Berlese): A – larva, region of right leg II insertion, ventral view, showing Claparède’s organ (insert = closeup of protective scale, seta 1c); B – adult, ventrosejugal region; C – adult, podosomal region, ventral view (uncleared specimen in glycerine * = extrinsic leg III muscle inserting onap.sj); D – insertions of legs I, II, ventrolateral view, showing declivity bordered by ridger2 (* = articulation of trochanter); E – cleared adult, cross section at level of apodeme 1, anterior view; F – same, at level of apodeme 2, posterior view; G – supracoxal seta eI of two different adults from New York; H – same, from eastern Canada (top Nova Scotia, bottom New Brunswick with one broken tine); I – same, from northwestern North America (from top: Alberta, two examples from Northwest Territories, Alaska); J – same, from Palaearctic populations (from top: two examples from Sweden, Germany (tritonymph), Khabarovsk). Scale bars 20 µm (C-F); 10 µm (A, B); 5 µm (G-J, to same scale).

Figure 9 Eulohmannia ribagai(Berlese): A – genital region of female, ventral view (focused inside genital vestibule; white arrow on soft cuticle partially isolating part of aggenital sclerite); B – tritonymph, insertions of tendons from two fascicles of posterior dorsoventral muscle (separate insertions at top, partly attached insertions at bottom); C – posterior half of hysterosoma, ventrolateral view, showing two fascicles of posterior dorsoventral muscles (adult female from China); D – male spermatopositor (specimen from NW Territories, Canada); E – sagittal view of female genital region in polarized light, showing ovipositor (setaeτ3, τ4 out of focus) and layered articulating cuticle between genital and anal plates; F – ovipositor, unpaired ventral lobe seenen face. Scale bars 20 µm (C); 10 µm (A, B); 5 µm (D-F).

Figure 10 Eulohmannia ribagai(Berlese): A – larva, subcapitulum, ventral view, palps omitted; B – protonymph, adoral lip; C – deutonymph, subcapitulum, ventral view, one palp omitted; D – tritonymph, rutellum, ventral view; E – larva, palp, abaxial view; F – same, enlarged tarsus; G – larva, chelicera, abaxial view; H – tritonymph, chelicera, adaxial view. Scale bars 20 µm (A-E, G, H); 5 µm (F).

Figure 11 Eulohmannia ribagai(Berlese): A – adult, left anal and adanal plates, ventral view; B – larva, paraproctal region, slightly flattened

Figure 15 Eulohmannia ribagai(Berlese): A – pretarsus of leg IV, deutonymph, lateral view; B – distal part of tarsus IV, adult (insert = enlargement of vestigial empodial claw); C – postpalpal seta of NY larva (top) and adult from Sweden (bottom); D – famulus of tritonymph abaxial view (with insertion of broken setaft”); E – same, adult from Cape Breton; F – same, adult from Sweden; G – larva, partial dorsal view of right genu I; H – larva, left tarsus I, ventral view (setaea” andpl” out of focus); I – same, deutonymph (setaplʹ out of focus); J – same, tritonymph; K – adult from Sweden, left tarsus I, adaxial view; L – same, but right tarsus, abaxial view; M – adult, lower portion of left tarsus I, adaxial view; N – microsculpture of tarsus I. Scale bars 20 µm (K, L); 10 µm (H-J, M); 5 µm (A, B, D-F); 2 µm (C, G, N).

Figure 16 A-F. Eulohmannia ribagai(Berlese): A – contents of esophagus (left) and accumulating food bolus in ventriculus (right) in strongly cleared adult (arrows to plant tracheal fragments); B – food bolus in ventriculus of cleared Tn (Germany); C – partially filled bolus in colon of slightly cleared adult, two focal planes (Sweden; white arrow to gelatinous outer layer, black arrows to possible bryophyte spores); D fecal pellet in postcolon of adult (arrow to fungal hypha); E – fecal pellet in postcolon of adult (Nova Scotia); F – fecal pellet in postcolon of adult (Alberta) with microsporidians in cleared gut wall (insert = enlargement of microsporidians, 2 µm long). G-L. Eulohmannia bifurcata Fujikawa, holotype (13642): G – habitus, with rectangles marking location of other images; H – region of podocephalic canal, ventral to top (right insert = enlarged setaeI); I – empodium of pretarsus IV; J – chelicera, abaxial view (insert = enlargement of cotyloid region, arrow on edge of articulating cuticle); K – rutellum, ventral view; L – distal part of tarsus I, midline focus (image inverted vertically for consistency); M – palp tarsus, abaxial (top), adaxial (bottom). Scale bars 100 µm (G); 20 µm (A-F all to same scale); 10 µm (H, J); 5 µm (K-M); 2 µm (I).

Figure 17 Eulohmannia bifurcataFujikawa, paratypes: A – paratype 13643A, habitus (indicating positions of B–D); B – posterior region of hysterosoma, ventrolateral view; C – marginal region of notogaster, above bandna; D – proterosoma dorsal to trochanters I, II; E – paratype 13644A, ventral habitus (indicating positions of F, G); F – lateral region of epimeres I and II (insert = posterolateral corner of II, deeper focus) G – posterolateral region of hysterosoma; H – paratype 13643B, posterior left corner of notogaster, dorsal view (*, ** indicate internal tissues or medium artifacts apparently mistaken forgla andip, respectively). Scale bars 100 µm (A, E); 20 µm (B, G); 10 µm (C, D, F, H).

Figure 18 Eulohmannia bifurcataFujikawa (A-D) andEulohmanniaspp. (E-I): A – holotype (13642), right anogenital region seen by trans- parency (black arrow to separate, ′island-like′ sclerite); B – paratype 13643A, genu and tibia I; C – same, tibia and tarsus II; D – same, leg IV (arrows to edge of adaxial declivity); E –Eulohmanniasp. A from Aborigen, Russian Far East, lateral view of gravid female; F – same specimen, ventral lobe of ovipositor (rectangle in A); G – male of same species, ventral view of spermatopositor; H –Eulohmanniasp. B from Kashmir, lateral view of gravid female; I – same specimen tarsus II (indicated by rectangle in H), with enlargement of distal region (arrow basal spine of empodial claw). Scale bars 50 µm (E, H); 20 µm (B, C); 10 µm (A, D, I); 5 µm (F, G).