- kabutoiwaensis, Tilia
- kadonosawaensis, Turritella
- kaempferi, Larix
- kaempferi, Rhododendron
- kaerimizensis, Parafusulina
- kaerimizuensis, Parafusulina
- kagaensis, Trophon
- kagaensis, Trophonopsis
- kagamianus, Kotorapecten
- kagamianus, Mizuhopecten
- kagamianus subsp. moniwaensis, Kotorapecten
- kagamianus subsp. moniwaensis, Patinopecten
- kagamianus, Patinopecten
- kagana, Boreotrophon
- kagana, Oenopota
- kagitoriensis, Cornucoquimba
- kagoshimensis, Anadara
- kaizensis, Yabeina
- kakehataensis, Anadara
- kakehataensis, Scapharca
- kakimii, Portlandia
- Kakisakiensis, Chlamys
- kakumana, Thracia
- Kalopanax pictus
- Kalopanax septemlobus
- kamakurensis, Fulgoraria
- kameii, Hidaella
- kamtschaticus, Aruncus dioicus
- kamtschatkana subsp. koyamai, Haliotis
- kanbaraensis, Patinopecten
- Kandelia, genus
- Kaneharaia kaneharai
- kaneharai, Cerithium
- kaneharai, Chlamys
- kaneharai, Dosinia
- kaneharai, Kaneharaia
- kaneharai, Mimachlamys
- kaneharai, Picea
- kaneharai, Proclava
- kannoi, Dosinia
- kanoi, Picea
- kantoense, Vasticardium
- kantoensis, Cylichna
- karatsuensis, Turritella
- karsteni, Eponides
- kasiwazakiensis, Cassidulina
- kasiwazakiensis, Cassidulita
- katayamai, Minetrigonia
- katayosensis, Lucinoma
- katoi, Triticites
- katokiyomasai, Cervus grayi
- Katsura
- katsurai, Donacia
- kawadai, Halobia
- kawagensis, Dosinia
- kawagensis, Phacosoma
- kawaii, Parafusulina
- kawamurai, Akebiconcha
- kawamurai, Calyptogena
- kawasakii, Dictyozamites
- kawasakii, Plesiotexanites
- kawasakii, Texanites
- kazusense, Epitonium
- kazusensis, Cervus
- kazusensis, Nipponicervus
- kazusensis, Trionyx
- Keaki
- Keenaea, genus
- Keenaea samarangae
- keenae, Mytilisepta
- keenae, Schizothaerus
- keenae, Tresus
- Keenocardium californiense
- kegaki, Saccostrea
- Kelletia, genus
- Kennerlia, genus
- Kennerlia wardiana
- Kentriodontid
- Kentriodontidae‰È
- kenyoshiensis, Fortipecten
- kernensis, Allodesmus
- Kerria japonica
- kesslerense, Phaneroceras
- kesslerense, Pseudoparalegoceras
- Keteleeria, genus
- Keteleeria davidiana
- Keteleeria ezoana
- Kewia minoensis
- Kewia minuta
- Keyhole limpet
- kidoi, Comptonia
- kiiensis cipangoana, Venericardia
- kiiensis, Terebratulina
- kikuchiana, Nipponitrigonia
- kikuchii, Paraleptolepis
- Kilinora spiralis
- kimurai, Mizuhopecten
- kimurai murayamai, Mizuhopecten
- kimurai nakosoensis, Mizuhopecten
- kimurai nakosoensis, Patinopecten
- kimurai, Patinopecten
- kimurai ugoensis, Mizuhopecten
- kimurai, Yaadia
- kinosakii, Parafusulina
- kinryuensis, Sinomegaceros
- kintaichiensis, Kotorapecten
- kintaichiensis, Masudapecten
- kintaichiensis, Mizuhopecten
- kintaichiensis, Patinopecten (Masudapecten)
- kintaichiensis, Patinopecten
- kintaichiensis, Patinopecten yamasakii
- kinuta, Galium
- kioroshiensis, Ruditapes variegata
- kioroshiensis, Venerupis aspera
- kiritaniana, Neverita
- kiriuensis, Pseudophillipsia
- kiryuensis, Eolyttonia
- kishinouyei, Schizocythere
- kitadaniensis, Fukuiraptor
- kitakamiensis, Schedohalysites
- kitamurai, Cavilucina
- kittonii, Aulacodiscus
- kiyonoi, Trisidos
- kizakiensis, Odostomia
- kobayashii, Cancellaria
- kobiwakoensis, Sinanodonta
- Kobushi magnolia
- kobus, Magnolia
- kochi, Ochetoclava
- kochi, Rhinoclavis
- Koch's vertagus
- Koelreuteria, genus
- kokozuraensis, Angulogerina
- kokozuraensis, Trifarina
- kokuraensis, Diplomystus
- kokurensis, Euestheria
- kometubus, Nassarius
- komotai, Hypoturrilites
- kondoi, Otozamites
- kongiensis, Nuculana confusa
- kongiensis, Saccella
- kongiensis, Saccella confusa
- Koninckocarinia flexuosa
- Koninckophyllum, genus
- konishii, Cunninghamia
- konnoi, Lima
- konnoi, Saccella
- Konosirus punctatus
- koraiensis, Pinus
- Korean birch
- Korean mulberry
- Korean pine
- Korean raspberry
- koribai, Picea
- koromogawana, Neptunea
- kosasana, Bellamya
- kosasanus, Viviparus
- koshibensis, Diodora yokoyamai
- koshibensis, Fulgoraria
- kosibensis, Diodora yokoyamai
- koslovae, Dictyomitra
- kosodeensis, Isastrea
- kossmati, Canadoceras
- kotoi, Daonella
- kotoi kotoi, Miogypsina
- kotoi, Miogypsina
- kotoi, Miogypsina kotoi
- Kotorapecten kagamianus
- Kotorapecten kagamianus subsp. moniwaensis
- Kotorapecten kintaichiensis
- Kotorapecten moniwaensis
- Kotorapecten yamasakii
- kousa, Cornus
- koyamae, Picea
- koyamai, Haliotis kamtschatkana
- Koyama's spruce
- kozaiensis, Babylonia
- kubara, Barbatia
- Kubikichthys raris
- kuboi, Cristaria
- Kueichouphyllum, genus
- Kueichouphyllum sinense
- Kueichouphyllum yabei
- kurakiensis, Mitra
- kuraokaensis, Acanthohalysites
- kuraokensis, Halysites
- kurilensis, Modiolus
- kurodai, Aphrodora
- kurodai, Lunella
- kurodai, Papyridea
- kurosawaensis, Patinopecten
- kurosio, Turritella
- kurumensis, Geratrigonia
- kuzuensis, Metriolepis
- kuzuensis, Pseudophillipsia
- kuzuryuensis, Cladophlebis
- kuzuüensis, Meles leucurus
- kuzuüensis, Putorius