List of arachnids of Ireland

There are approximately 1,107 species of arachnid native to Ireland. Not up to date for all taxa. Arachnids are eight-legged chelicerate arthropods with pedipalps and bodies divided into two tagmata.
The most best known and familiar group in Ireland is the spiders, and there are also several species of harvestman (daddy-long-legs), ticks, mites and pseudoscorpions. Arachnid groups absent from Ireland include true scorpions, whip scorpions, solifuges, cave spiders, microwhip scorpions, hooded tick spiders and tarantulas.
Subclass Dromopoda.
Order Opiliones (harvestmen / daddy-long-legs).
15 native species and three species which are not considered to be native: "Odiella spinosus", "Opilio parietinus" (Phalangiidae) and "Dicranopalpus ramosus" (Leiobunidae)
Order Pseudoscorpionida (false scorpions).
17 species
Subclass Acari (ticks and mites).
At least 684 species
Order Ixodida (ticks).
Family Ixodidae.
10 species
Family Argasidae (soft ticks).
2 species
Order Prostigmata (sucking true mites).
249 species
Family Alycidae.
4 species
Family Arrenuridae.
5 species
Family Bdellidae.
5 species
Family Ereynetidae.
1 species
Family Eriophyidae (gall mites).
52 species 
Family Erythraeidae.
7 species
Family Eupodidae.
2 species
Family Eylaidae.
3 species
Family Halacaridae (marine mites).
44 species
Family Hydrodromidae.
1 species
Hydrachnidiae.
2 species 
Family Hydryphantidae.
2 species
Family Hygrobatidae.
6 species
Family Lebertiidae.
11 species
Family Limnesiidae.
2 species
Family Meyerellidae.
3 species
Family Microtrombidiidae.
4 species
Family Mideidae.
1 species
Family Mideopsidae.
1 species
Family Nanorchestidae.
2 species
Family Oxidae.
1 species
Family Penthaleidae.
2 species
Family Phytoptidae.
2 species
Family Pionidae.
14 species
Family Podothrombiidae.
1 species
Family Rhagidiidae.
4 species
Family Scutacaridae.
1 species
Family Sperchontidae.
7 species
Family Stigmaeidae.
3 species
Family Tanaupodidae.
1 species
Family Tarsonemidae.
14 species
Family Tetranychidae.
6 species
Family Teutoniidae.
1 species
Family Torrenticolidae.
9 species
Family Trombiculidae.
1 species
Family Tydeidae.
15 species
Family Unionicolidae.
6 species
Suborder Oribatida (moss mites / beetle mites).
173 species have been identified for the Republic of Ireland
Family Achipteriidae.
4 species
Family Adelphacaridae.
1 species
Family Ameronothridae.
7 species
Family Banksinomidae.
1 species
Family Belbidae.
1 species
Family Brachychthoniidae.
19 species
Family Caleremaeidae.
1 species
Family Camisiidae.
6 species
Family Cepheidae.
3 species
Family Cosmochthoniidae.
1 species
Family Euphthiracaridae.
1species
Family Euzetidae.
2 species
Family Hermanniidae.
7 species
Family Hypochthoniidae.
2 species
Family Liodidae.
1 species
Family Malaconothridae.
6 species
Family Mycobatidae.
4 species
Family Nanhermanniidae.
4 species
Family Nothridae.
2 species
Family Perlohmanniidae.
1 species
Family Phthiracaridae.
4 species
Suborder Brachypylina.
Family Carabodidae.
5 species
Family Ceratozetidae.
12 species
Family Chamobatidae.
4 species
Family Ctenobelbidae.
1 species
Family Cymbaeremaeidae.
1 species
Family Damaeidae.
3 species
Family Eremaeidae.
1 species
Family Galumnidae.
2 species
Family Haplozetidae.
1 species
Family Humerobatidae.
1 species
Family Hydrozetidae.
1 species
Family Liacaridae.
4 species
Family Limnozetidae.
2 species
Family Metrioppiidae.
1 species
Family Micreremidae.
1 species
Family Neoliodidae.
1 species
Family Oppiidae.
16 species
Family Oribatellidae.
3 species
Family Oribatulidae.
7 species
Family Passalozetidae.
1 species
Family Phenopelopidae.
8 species
Family Protoribatidae.
1 species
Family Protoribatidae.
1 species
Family Punctoribatidae.
1 species
Family Quadroppiidae.
1 species
Family Scheloribatidae.
2 species
Family Scutoverticidae.
2 species
Family Steganacaridae.
2 species
Family Suctobelbidae.
6 species
Family Tectocepheidae.
1 species
Family Thyrisomidae.
2 species
Family Xenillidae.
1 species
Order Araneae (spiders).
390 species belonging to 31 families
See also.
Encyclopedia of Life online has many images via search
Dictynoidea Placements
References.
Helsdingen, P.J. van, 1996 A county distribution of Irish spiders, incorporating a revised catalogue of the species "Irish Naturalists' Journal" Special Issue
Identification.
Key works are:-
Peter C. Barnard, 1999 "Identifying British insects and arachnids: an annotated bibliography of key works"
Cambridge University Press provides a comprehensive list of identification literature.