Histiogaster altilis, KolesnikovK & VorontsovK & PerkovskyK & KlimovK, 2025

KolesnikovK, Vasiliy B., VorontsovK, Dmitry D., PerkovskyK, Evgeny E. & KlimovK, Pavel B., 2025, An exceptionally well-preserved Eocene fossil mite, Histiogaster altilis sp. n. (Acari: Astigmata), from tree sap: Evidence of morphological and ecological niche conservatism, with a review of fossil Astigmata, Acarologia 65 (1), pp. 213-241 : 216

Histiogaster altilis sp. n.

Zoobank: E453FB5A-EA48-4904-8CB0-D52EA6510ABF ( Figs 1–18 )

Figures

Figure 1. Pieces of amber after preliminary trimming: A, B⚶parts of the pieces SIZK K-15219 and K-15220, respectively. Both pieces contain clouds of micro-inclusions, interpreted here as emulsion of phloem sap; C,E,G ⚶plexus of spiral filamentous hyphae, shown at different magnifications (part of the amber piece SIZK K-15219); D, F, H, I ⚶microinclusions filling the amber piece, at different magnifications. Note the mite specimen (K-15219-E), imaged before preparation, in F.

Figure 2. Histiogaster altilis sp. n., adult female, holotype, specimen K-15220-B, dorso-lateral view, micrographs: A⚶focus-stacked light micrograph, showing the imprint in amber (outer contour) and, inside it, fossilized remains of a mite; ⚶B maximum intensity projection of confocal stack. Note the alveoli of setae e1 brightly fluorescent; C ⚶gnathosoma, super-resolution (Airyscan) confocal stack, maximum intensity projection; inset shows supracoxal seta (scx) separately stacked in Helicon Focus; D, E ⚶bifurcate Grandjean’s organ was best resolved in transmitted light (100x, DIC) and in the CLSM scan (63x, Airyscan).

Figure 3. Histiogaster altilissp. n., adult female, holotype, specimen K-15220-B ventral view, micrographs: A⚶habitus image; B⚶gnathosoma, DIC micrograph; C⚶same, confocal image; D⚶tarsus I; E ⚶legs III and IV; F⚶anal region; G⚶genital region. All except B, maximum intensity projections of confocal stacks.

Figure 4. Histiogaster altilis sp. n., adult female, holotype, specimen K-15220-B: A ⚶dorsal aspect; B⚶ventral aspect; C ⚶genital structures; D ⚶anal region; arrow indicates inseminatory canal. Internal structures shown by dotted red line. Green outline shows the contour of the mite exoskeleton inside the amber imprint.

Figure 5. Histiogaster altilis sp. n., adult female, holotype, specimen K-15220-B: A, B ⚶legs I; C, D⚶legs II; E, F⚶legs III; G, H⚶legs IV; I ⚶gnathosoma with palpi, ventral aspect. Green outline shows the contour of the mite exoskeleton inside the amber imprint.

Figure 6. Histiogaster altilis sp. n., adult female, specimen K-15219-B, paratype, lateral views, micrographs: A⚶maximum intensity projection of confocal stack. B ⚶DIC light micrograph. C ⚶ chelicera, enlarged.

Figure 7. Histiogaster altilissp. n., adult female, specimen K-15219-B, paratype: A ⚶lateral view; B, C ⚶right and left legs I, respectively; D, E ⚶legs II; F, G⚶legs III; H, I⚶legs IV. Green outline shows the contour of the mite exoskeleton inside the amber imprint.

Figure 8. Histiogaster altilis sp. n., adult female, specimen K-15220-A1, paratype, ventral and frontal views: A ⚶ventral view, maximum intensity projection of confocal stack. Gnathosomal structures and most of the legs are projected ventrally;⚶ Bfrontal view, showing gnathosoma

Figure 9. Histiogaster altilis sp. n., females: A ⚶specimens K-15220-A2 and A3 in the block of amber; B ⚶specimen K-15220-С; C, E ⚶ specimen K-15220-A2 and A3, respectively; D ⚶specimen K-15220-C; F, specimen K-15220-D; G ⚶specimen K-15220-C, gnathosoma and legs I, Airyscan super-resolution image. A-C, E, F, focus-stacked light micrographs. D, G, maximum intensity projections.

Figure 10. Histiogaster altilis sp. n., adult male, specimen K-15219-A, dorso-lateral view, micrographs: A, B⚶DIC light micrographs showing the dorsal aspect of the mite and the bifurcate Grandjean’s organ⚶; C maximum intensity projection of the confocal stack. Note the bright fluorescence of setae1 clearly shown against the body; D, E, ⚶ Funidentified microscopic structures attached to (or originating from) the posterior part of the body; D, E⚶dorsal view; F⚶posterior view. One of the possible interpretations could be that these are fractures in amber.

Figure 11. Histiogaster altilis sp. n., adult male, specimen K-15219-A, ventro-lateral view, confocal images: A ⚶whole mite; B ⚶bifurcate Grandjean’s organ; C⚶parts of gnathosoma and palpi; D, E⚶genital structures. All images are maximum intensity projections except E, which is a manually focus-stacked image from the part of the stack shown in D.

Figure 12. Histiogaster altilissp. n., adult male, specimen K-15219-A:A ⚶lateral view, combined transmitted and reflected light; ⚶Benlarged leg IV; C⚶gnathosoma, palpi and legs I, frontal view; D ⚶enlarged gnathosoma; B, C, D ⚶maximum projections of confocal stacks; B, D ⚶ Airyscan super-resolution mode.

Figure 13. Histiogaster altilis sp. n., adult male, specimen K-15219-A: A ⚶dorso-lateral view; B⚶ventro-lateral view; C ⚶gnathosoma; D⚶ genital structures. Green outline shows the contour of the mite exoskeleton inside the amber imprint.

Figure 14. Histiogaster altilis sp. n., adult male, specimen K-15219-A: A ⚶part of gnathosoma in lateral view and right legs I and II; ⚶ Bright leg III; C⚶right leg IV; D⚶left legs I and II; E⚶left leg III. Green outline shows the contour of the mite exoskeleton inside the amber imprint.

Figure 15. Histiogaster altilis sp. n., adult male, specimen K-15219-C, micrographs: A ⚶dorsal view, maximum intensity projections of confocal stack. Note the high level of amber fluorescence around the mite; ⚶ Bventral view, confocal stack, background subtraction, inverted maximum intensity projection; C ⚶genitalia, lateral view, confocal image; D⚶projection of the opisthosomal shield with a 4-lobed, fan-like structure, characteristic of Histiogaster males, ventral view, DIC light micrograph; E⚶genitalia, ventral view, DIC light micrograph; F ⚶ genitalia, ventral view, confocal image, maximum intensity projection; G⚶anal suckers, confocal image, maximum intensity projection.

Figure 16. Histiogaster altilis sp. n., adult male, specimen K-15219-E, micrographs: A ⚶ventral view, maximum intensity projection of confocal stack; B ⚶anal suckers, confocal Airyscan super-resolution mode, maximum intensity projection; C, D ⚶the same, partial stacking showing the ps3 setae.

Figure 17. Histiogaster altilis sp. n., adult male, specimen K-15219-C: A ⚶dorsal aspect; B⚶ventral aspect; C ⚶caudal aspect.

Figure 18. Histiogaster altilis sp. n., adult male, specimen K-15219-C: A ⚶gnathosoma, palpi and legs I, ventral aspect; B, C⚶legs II; D, E⚶legs III; F, G⚶legs IV.