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 | 5 | 2019 |
| beetle | Kateretes rufilabris | a pollen or sap beetle | 6 | 2001 |
| beetle | Kibunea minuta | a click beetle | 25 | 2018 |
| beetle | Kissister minimus | a carrion beetle | 3 | 2018 |
| beetle | Korynetes caeruleus | a chequered beetle | 1 | 1969 |
| bug | Kalama tricornis | a lace bug | 4 | 2016 |
| bug | Kleidocerys ericae | a ground bug | 1 | 2016 |
| bug | Kleidocerys resedae | Birch Catkin Bug | 48 | 2019 |
| bug | Kleidocerys truncatulus | a ground bug | 3 | 1998 |
| fungus | Kretzschmaria deusta | a fungus | 5 | 1997 |
| fungus | Kretzschmaria deusta | Brittle Cinder | 52 | 2018 |
| fungus | Kuehneola uredinis | Pale Bramble Rust | 27 | 2017 |
| fungus | Kuehneromyces mutabilis | a fungus | 14 | 2009 |
| fungus | Kuehneromyces mutabilis | an agaric | 69 | 2014 |
| leech, flatworm or ribbon worm | Kontikia ventrolineata | a kontikia flatworm | 1 | 2015 |
| moth or butterfly - macro moth | Korscheltellus fusconebulosa | Map-winged Swift | 2 | 1979 |
| moth or butterfly - macro moth | Korscheltellus lupulina | Common Swift | 824 | 2020 |
| plant | Kerria japonica | Kerria | 36 | 2019 |
| plant | Kickxia elatine | Sharp-leaved Fluellen | 116 | 2017 |
| plant | Kickxia spuria | Round-leaved Fluellen | 109 | 2015 |
| plant | Knautia arvensis | Field Scabious | 1367 | 2020 |
| plant | Knautia macedonica | a flowering plant | 2 | 2019 |
| plant | Kniphofia | a Kniphofia species (unidentified) | 2 | 2013 |
| plant | Kniphofia praecox | Greater Red-hot-poker | 2 | 1998 |
| plant | Kniphofia uvaria | Red-hot-poker | 2 | 2018 |
| plant | Koeleria macrantha | Crested Hair-grass | 300 | 2018 |
| plant | Koeleria macrantha (sens.lat.) | Crested Hair-grass sens. lat. | 2 | 1986 |
| 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 |
| spider | Kaestneria dorsalis | a money spider | 1 | 1997 |
| spider | Kaestneria pullata | a money spider | 2 | 1999 |
| true fly - | Keroplatidae | a Keroplatidae species (unidentified) | 1 | 2019 |
| true fly - (diptera) | Kowarzia bipunctata | an insect - true fly (Diptera) | 1 | 2002 |
| true fly - midge, gnat or mosquito | Keroplatus testaceus | a fungus gnat | 2 | 2000 |
| true fly - midge, gnat or mosquito | Kiefferia pericarpiicola | a gall midge | 1 | 2013 |