Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| ant, bee, wasp, sawfly or ichneumon (and others) | Kristotomus laetus | an ichneumon wasp | 1 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Kristotomus ridibundus | an ichneumon wasp | 2 | 2003 |
| beetle | Kalcapion semivittatum | a seed weevil | 5 | 2009 |
| beetle | Kateretes pusillus | a pollen or sap beetle | 6 | 2022 |
| beetle | Kateretes rufilabris | a pollen or sap beetle | 7 | 2020 |
| beetle | Kissister minimus | a carrion beetle | 3 | 2018 |
| beetle | Kissophagus vicinus | a bark or ambrosia beetle | 2 | 2022 |
| beetle | Korynetes caeruleus | a chequered beetle | 1 | 1969 |
| beetle | Kyklioacalles roboris | a weevil | 4 | 2021 |
| bug | Kalama tricornis | a lace bug | 4 | 2016 |
| bug | Kelisia guttulifera | a planthopper | 1 | 2019 |
| bug | Kelisia sabulicola | a planthopper | 2 | 2019 |
| bug | Kleidocerys ericae | a ground bug | 2 | 2021 |
| bug | Kleidocerys resedae | Birch Catkin Bug | 92 | 2024 |
| bug | Kleidocerys truncatulus | a ground bug | 3 | 1998 |
| bug | Kybos ludus | a leafhopper | 3 | 2023 |
| bug | Kybos smaragdulus | a leafhopper | 2 | 2023 |
| fungus | Kiliasia episema | a fungus | 2 | 2016 |
| fungus | Kneiffiella barba-jovis | a basidiomycete fungus | 1 | 2012 |
| fungus | Kneiffiella subalutacea | a basidiomycete fungus | 1 | 2010 |
| fungus | Kretzschmaria deusta | Brittle Cinder | 67 | 2023 |
| fungus | Kuehneola uredinis | Pale Bramble Rust | 30 | 2023 |
| fungus | Kuehneromyces mutabilis | Sheathed Woodtuft | 87 | 2023 |
| lichen | Karstenia rhopaloides | a lichen | 1 | 1991 |
| lichen | Kuettlingeria ceracea | a lichen | 1 | 2011 |
| lichen | Kuettlingeria teicholyta | a lichen | 8 | 2011 |
| moss | Kindbergia praelonga | Common Feather-moss | 355 | 2024 |
| moth or butterfly - macro moth | Korscheltellus fusconebulosa | Map-winged Swift | 2 | 1979 |
| moth or butterfly - macro moth | Korscheltellus lupulina | Common Swift | 1071 | 2024 |
| plant | Kerria japonica | Kerria | 38 | 2019 |
| plant | Kickxia elatine | Sharp-leaved Fluellen | 118 | 2017 |
| plant | Kickxia spuria | Round-leaved Fluellen | 109 | 2015 |
| plant | Knautia arvensis | Field Scabious | 1597 | 2024 |
| plant | Knautia macedonica | a flowering plant | 2 | 2019 |
| plant | Kniphofia | a Kniphofia species (unidentified) | 2 | 2013 |
| plant | Kniphofia uvaria | Red-hot-poker | 2 | 2018 |
| plant | Kniphofia x praecox | Greater Red-hot-poker | 2 | 1998 |
| plant | Koeleria macrantha | Crested Hair-grass | 304 | 2018 |
| plant | Koeleria vallesiana | Somerset Hair-grass | 66 | 2019 |
| plant | Koeleria vallesiana x macrantha | a crested hair-grass | 2 | 2000 |
| plant | Koelreuteria paniculata | Pride-of-India | 2 | 2015 |
| plant | Koenigia polystachya | Himalayan Knotweed | 12 | 2004 |
| spider | Kaestneria dorsalis | a money spider | 1 | 1997 |
| spider | Kaestneria pullata | a money spider | 2 | 1999 |
| springtail | Kalaphorura burmeisteri | a springtail (Collembola) | 1 | 1925 |
| true fly - | Keroplatidae | a Keroplatidae species (unidentified) | 1 | 2019 |
| true fly - midge, gnat or mosquito | Keroplatus testaceus | a fungus gnat | 3 | 2021 |
| true fly - midge, gnat or mosquito | Kiefferia pericarpiicola | a gall midge | 2 | 2023 |
| true fly - robber, empid or dolichopid fly | Kowarzia bipunctata | a dance fly | 3 | 2002 |