Systematics of Inquiline Gall Mites (Eriophyoidea)

As of 29 September 2026 – Inquiline gall mites; systematics to genus level, with species included as biological examples

This overview covers genera of Eriophyoidea for which at least one well-supported record of inquilinism, or an explicitly discussed record of inquilinism, is available . The genus itself is therefore not necessarily “inquiline”: in many genera, this behaviour concerns only individual species. The species listed are not an additional systematic rank , but documented examples of the biological behaviour.

What does “inquiline” mean here?
Here, an inquiline is defined as a gall mite that uses a gall structure already produced by another organism as its habitat, without itself causing the actual formation of that gall. In Eriophyoidea, both galls produced by other gall mites and galls produced by other gall-forming organisms, particularly gall midges, are documented. Because the term “inquiline” has not always been used consistently in the older literature, secure, probable and historically uncertain cases are distinguished. ¹

Species status:
✓ securely documented = the source explicitly describes the species as an inquiline, or the context is unambiguous.
? probable / discussed = the interpretation of the species as an inquiline is supported in the literature but is not conclusively established.
(historical) = an older record whose current biological or taxonomic interpretation is uncertain.

Superfamily Eriophyoidea Nalepa

Family Eriophyidae Nalepa, 1898

Subfamily Cecidophyinae Keifer, 1966

Cecidophyini

Genus:

Cecidophyopsis Keifer, 1966
? Cecidophyopsis grossulariae – described as a foliar species and documented as an inquiline in bud galls of C. ribis.²
(historical) Cecidophyopsis vermiformis – classically reported as an inquiline in large bud galls of Phytoptus avellanae and also reported from other gall mite galls; however, recent studies show that the species itself may be involved in the formation of “big buds”. ³

Inquiline status:

Secure or discussed for individual species. In particular, C. grossulariae has a documented inquiline lifestyle in C. ribis galls; in C. vermiformis, the older interpretation of inquilinism is no longer biologically unambiguous.²³

Subfamily Eriophyinae Nalepa, 1898

Acerini

Genus:

Aceria Keifer, 1944
? Aceria trichophila – found on Quercus ilex together with A. ilicis in erineal growths; the authors consider it possible that A. trichophila lives as an inquiline in the erineal growths produced by A. ilicis. Inquilinism is therefore explicitly discussed, but has not been conclusively demonstrated.¹⁸

Inquiline status:

Discussed for A. trichophila . The available literature treats the species as a possible inquiline in the erineal growths of Aceria ilicis ; a secure inquiline status has not been established. ¹⁸

Eriophyini

Genus:

Eriophyes von Siebold, 1851
✓ Eriophyes prunidemissae – reproduces in buds and later enters the galls produced by E. emarginatae; there it may outnumber the gall inducer.⁴

Inquiline status:

Secure for individual species. The case of E. prunidemissae is explicitly documented by a detailed biological study.⁴

Subfamily Phyllocoptinae Nalepa, 1892

Anthocoptini

Genera:

Aculops Keifer, 1966
✓ Aculops acericola – an inquiline in erineal growths of Eriophyes psilomerus on Acer pseudoplatanus; the recent British review explicitly states that the species does not itself cause the erineal growth in question.⁵

Aculus Keifer, 1959
✓ Aculus dormitor – an inquiline in the galls of Phyllocoptes didelphis on Populus tremuloides.⁶
? Aculus minutissimus – associated with red maple erineum; the species is listed as a possible inquiline, but the roles of gall inducer and inquiline have not been conclusively established. ⁷
Anthocoptes Nalepa, 1892
✓ Anthocoptes ericameriella – explicitly reported as an inquiline in gall midge galls (Cecidomyiidae). ⁸

Inquiline status:

Securely documented for individual species. The three examples cited also illustrate different situations: inquilines in erineal growths produced by other gall mites, in enclosed gall structures, and in gall midge galls. ⁵ ⁶ ⁸

Acaricalini

Genus:

Acaricalus Keifer, 1940
? Species not securely identified – for Acaricalus records in bud or tissue damage caused by other gall mites are discussed as a possible inquiline situation; a species-specific record could not be securely established here. ⁹

Inquiline status:

Discussed only. The genus is therefore retained in the overview, but the particular species is not treated as a securely documented inquiline. ⁹

Phyllocoptini

Genera:

Epitrimerus Nalepa, 1892
✓ Epitrimerus fagi – lives as an inquiline in the galls of Acalitus plicans on beech. ¹⁰
Monochetus Nalepa, 1898
? Monochetus sulcatus – in the beech galls of Acalitus plicans as a possible second species alongside E. fagi ; it remains unclear whether it is itself a gall inducer or an inquiline. ¹⁰
Phyllocoptes Nalepa, 1887
✓ Phyllocoptes thymi – reported as an inquiline in the gall formations of Aculus minor on Thymus serpyllum.¹¹
✓ Phyllocoptes canarii – listed as a gall inquiline on Canarium littorale.¹²
✓ Phyllocoptes heterozonus – likewise listed as a gall inquiline on Canarium littorale.¹²

Inquiline status:

Epitrimerus and Phyllocoptes : secure for individual species. Monochetus : uncertain ; the case of M. sulcatus remains unresolved between gall inducer and inquiline. ^{10

–

12}

Tegonotini

Genera:

Shevtchenkella Bagdasarian, 1978
(historical) Shevtchenkella serrata – older literature listed the species as an inquiline on Acer ; however, recent studies show an independent, seasonally dimorphic lifestyle on leaves and reproductive organs. ¹³
Tegonotus Nalepa, 1890
(historical) Tegonotus serratus – older records mention the species in connection with erineal growths on Acer ; its current biological classification as an inquiline is not sufficiently supported. ¹⁴

Inquiline status:

Historical or uncertain. These genera are not regarded as securely documented inquilines; the historical records are retained as such. ¹³ ¹⁴

Family Diptilomiopidae Keifer, 1944

Subfamily Diptilomiopinae Keifer, 1944

Genera:

Diptilomiopus Nalepa, 1916
✓ Diptilomiopus javanicus – originally explicitly described as an inquiline in bilobed galls caused by Aceria hemigraphidis on Hemigraphis confinis.¹⁵
✓ Diptilomiopus cerinus – explicitly described in 1952 as an inquiline on erineal growths of Coprosma australis.¹⁶
Diptacus Keifer, 1951
✓ Diptacus sacramentae – documented as a commensal inquiline in a gall structure produced by another gall mite. ¹⁷

Inquiline status:

Secure for individual species. Diptilomiopus includes species explicitly described as inquilines; a corresponding case is also documented for Diptacus.^{15

–

17}

Footnotes and explanatory notes

1. The term “inquiline” is not used entirely consistently in the Eriophyoidea literature. For erineal growths on Acer the British Plant Gall Society explicitly notes that some historical records require reassessment. British Plant Gall Society, A provisional key to eriophyoid mite erinea on Acer in Britain .
2. Cecidophyopsis grossulariae is described as a foliar species that can live as an inquiline in bud galls of C. ribis. Moročko-Bičevska et al. 2022, Annals of Applied Biology
3. Cecidophyopsis vermiformis was classically regarded as a harmless inquiline in the large bud galls of Phytoptus avellanae . However, recent studies show that C. vermiformis may itself be involved in the formation or development of the large buds, and that its precise role remains partly unresolved. Plant Health Australia 2024 ; Can Pest Management and Cultivar Affect Phytoptus avellanae Infestations on Hazelnut? 2024 .
4. Eriophyes emarginatae causes the finger- or club-shaped galls on Prunus. E. prunidemissae initially reproduces in buds and later enters the galls produced by E. emarginatae. Oldfield 1969, Annals of the Entomological Society of America 62: 269–277
5. Aculops acericola is explicitly interpreted in the current British review as an inquiline in erineal growths of Eriophyes psilomerus on Acer pseudoplatanus. The review also discusses earlier synonymies with Aculops aceris. British Plant Gall Society
6. Aculus dormitor is explicitly listed in the USDA account as an inquiline in the galls of Phyllocoptes didelphis on quaking aspen. Gallformers, source attribution to Keifer et al. 1982 .
7. Aculus minutissimus is associated with erineal growths on Acer rubrum; the available compilation explicitly lists the species with the note “may be an inquiline”. The case therefore remains open. Gallformers
8. Anthocoptes ericameriella is explicitly listed in Eriophyoidea ID as an inquiline in gall midge galls (Cecidomyiidae). Eriophyoidea ID – Anthocoptes .
9. For Acaricalus, no clearly established species-specific record of inquilinism is available; the genus is therefore included only as a discussed case.
10. Epitrimerus fagi is listed as an inquiline in the beech galls of Acalitus plicans; Monochetus sulcatus is instead described as a possible gall inducer or inquiline in the same galls. Compilation with references to W. N. Ellis, Plant Parasites of Europe
11. Phyllocoptes thymi is explicitly reported in the faunistic survey of South Tyrol as an inquiline in the gall formations of Aculus minor on Thymus serpyllum. Hellrigl, Faunistik der Gallmilben Südtirols
12. Phyllocoptes canarii and P. heterozonus are listed in a taxonomic overview of Eriophyoidea from Canarium as “gall inquilines”. Xu et al. 2017, Acarologia 57
13. Shevtchenkella serrata was historically reported as an inquiline. However, recent studies show two seasonal forms and a lifestyle on leaf undersides, buds, samaras and seedlings; the study interprets the species as vagrant and does not confirm inquilinism in a gall produced by another organism. Desnitskiy et al. 2023 .
14. The British Plant Gall Society cites historical records of Oxypleurites serratus (= Shevtchenkella serrata ) and a Tegonotus species as inquilines in erineal growths on Acer . Because of the historical and nomenclatural uncertainty, the case is not regarded here as a securely established current record of inquilinism. British Plant Gall Society .
15. Diptilomiopus javanicus was described as an inquiline in bilobed galls caused by Aceria hemigraphidis on Hemigraphis confinis. The subsequent revision of the genus confirms this historical description. Nomenclatural changes and new synonymy in Diptilomiopus
16. Diptilomiopus cerinus was described in 1952 with the explicit statement “Inquiline on erinose leaves” on Coprosma australis. The erineal growth had previously been attributed to Phyllocoptes coprosmac. Lamb 1952, Transactions and Proceedings of the Royal Society of New Zealand 80
17. Diptacus sacramentae is reported as a commensal inquiline in galls of Eriophyes laevis on Alnus; the species is otherwise also vagrant on the underside of the leaf. Dorset Nature, Eriophyes laevis
18. In studies of Quercus ilex , Aceria ilicis and Aceria trichophila were found together in erineal growths. The authors consider it possible that A. trichophila is an inquiline species in the erineal growths produced by A. ilicis ; this is explicitly presented as a possibility rather than as a confirmed record. Estrada-Venegas et al. 2016, Folia Entomológica Mexicana 2(2): 24–32 .

Literature – key sources

Alford, D. V. (2012): Pests of Ornamental Trees, Shrubs and Flowers , 2nd ed.
Estrada-Venegas, E. G. et al. (2016): Primeras citas fidedignas del género Aceria asociado a Quercus ilex L. y Q. coccifera L. para el nordeste de la Península Ibérica. Folia Entomológica Mexicana 2(2): 24–32.
British Plant Gall Society (2026): A provisional key to eriophyoid mite erinea on Acer in Britain .
Desnitskiy, A. et al. (2023): Deuterogyny and the association of two vagrant eriophyoid mites ... Zoological Studies 62:35.
Hellrigl, K.: Faunistics of gall mites of South Tyrol (Acari: Eriophyoidea) .
Lamb, K. P. (1952): A new species of Diptilomiopus ... Transactions and Proceedings of the Royal Society of New Zealand 80.
Moročko-Bičevska, I. et al. (2022): Cecidophyopsis mites and blackcurrant reversion virus on Ribes hosts. Annals of Applied Biology . DOI 10.1111/aab.12720 .
Oldfield, G. N. (1969): The biology and morphology of Eriophyes emarginatae and notes on E. prunidemissae . Annals of the Entomological Society of America 62: 269–277.
Xu, X.-Q. et al. (2017): A new eriophyid mite species in the genus Tegonotus ... Acarologia 57: 901–911.
Xue, X.-F. et al. (2024): Phylogenomics resolves the higher-level phylogeny of herbivorous eriophyoid mites. BMC Biology .

Scope: The mere occurrence of a gall mite in a gall structure is not considered sufficient evidence of inquilinism here; only cases explicitly described or discussed as inquilinism are included.