- Maackia amurensis
- maackianus, Potamogeton
- maackii, Papilio
- Mabellarca hiratai
- Macaca cyclopis
- Macaca fuscata
- Macaronichnus, ichnogenus
- machikanensis, Toyotamaphimeia
- Machilus, genus
- Machilus nathorsti
- Machilus ugoana
- Maclura tricuspidata
- Macluritidae, family
- Macoma, genus
- Macoma aomoriensis
- Macoma arctata
- Macoma asagaiensis
- Macoma calcarea
- Macoma calcarea izurensis
- Macoma golikovi
- Macoma incongrua
- Macoma izurensis
- Macoma (Macoma) calcarea
- Macoma nipponica
- Macoma oinomikadoi
- Macoma optiva
- Macoma orbiculata
- Macoma praetexta
- Macoma praetexta oinomikadoi
- Macoma (Rexithaerus) sectior
- Macoma sectior
- Macoma sejugata
- Macoma snohomishensis
- Macoma sookensis
- Macoma tokyoensis
- Macoma totomiensis
- Macridiscus aequilatera
- macrocheiricola, Delectopecten
- macrochisma ezoana, Monia
- macrochisma ezoanus, Placunanomia
- macrochisma, Monia
- macrochisma, Pododesmus
- macrodon, Yungkangichthys
- macroholcus, Heteraster
- macroholcus, Paraheteraster
- macroholcus, Washitaster
- Macromia, genus
- Macrophthalmus, genus
- Macrophthalmus japonicus
- Macrophthalmus latreillei
- Macrophthalmus (Mareotis) japonicus
- Macrophthalmus (Venitus) latreillei
- macropoda, Ilex
- macropoda, Trapa
- Macroschisma, genus
- Macrouridae, family
- Mactra, genus
- Mactra chinensis
- Mactra crossei
- Mactra nipponica
- Mactra quadrangularis
- Mactra sulcataria
- Mactra veneriformis
- Mactromeris, genus
- Mactromeris, genus
- Mactromeris polynyma
- Madake
- Madrepora oculata
- maedae, Modiolus
- Maedagonia crassoradiata
- Maedagonia yabei
- maekawai, Ternstroemia
- Magallana gigas
- Magallana nippona
- magarikawaensis, Nuculana
- magellanicus, Placopecten
- magnacornuta, Lychnocanoma
- magna, Fulgoraria
- magna, Fulgoraria megaspira
- magna, Trachydomia
- magna, Trachyspira
- magnifica, Hindsia
- magnifica, Nassaria
- magnifica yokoyamai, Nassaria
- magnificum, Cercidiphyllum
- Magnolia, genus
- Magnolia kobus
- Magnolia obovata
- Magnoliophyta
- maiyaense, Psygmophyllum
- maiyaensis, Paratrizygia
- major, Gablonzeria
- major, Potentilla fragarioides
- majus, Paleodictyon
- makinoi, Chrysanthemum
- makinoi, Trapa bispinosa
- Makiyama, genus
- Makiyama chitanii
- makiyamai, Anadara
- makiyamai, Brissopsis
- makiyamai, Onustus
- makiyamai, Siphonalia
- makiyamai, Tugurium
- Mako shark
- malasiaca, Anoplophora
- Maldanidae, family
- Malletia, genus
- Malletia inermis
- Malletia takeharai
- Malloproductus pexus
- Mallotus japonicus
- Mallotus, genus
- Malus sieboldii
- Malus toringo
- Mammal
- Mammalia, class
- Mammilla, genus
- mammillifera, Trapa
- Mammoth
- Mammuthus, genus
- Mammuthus paramammontheus shigensis
- Mammuthus primigenius
- Mammuthus protomammonteus
- Mammuthus shigensis
- Manchurian alder
- Manchurian elm
- Manchurian wild rice
- manchuriensis, Woodsia
- Mandarin melon berry
- mandraliscae, Cyclobalanopsis
- mandraliscae, Quercus
- mandshurica var. cordiformis, Juglans
- mandshurica subsp. hosenjiana, Juglans
- mandshurica var. japonica, Fraxinus
- mandshurica, Juglans
- mandshurica var. sachalinensis, Juglans
- mandshurica var. sieboldiana, Juglans
- manfredi, Eptingium
- Mangifera, genus
- manifesta, Spiroloculina
- manifesta, Thalassiosira
- Manila clam
- manilensis, Barnea
- manilensis inornata, Barnea
- manni ambigenus, Astriclypeus
- mannii ambigenus, Astriclypeus
- mannii minoensis, Astriclypeus
- mannii, Astriclypeus
- manpukujiense, Nonion
- manpukuziensis, Florilus
- manpukuziensis, Nonion
- manshurica, Trapa
- Mantelliceras japonicum
- Maple
- March fly
- Marcia genus
- Marcia japonica
- Mareotis japonicus
- margaritaceus, Modiolus
- margaritae, Neoschwagerina
- Margarites eos
- Margaritifera, genus
- marginata, Bulimina
- marginata, Fissurina
- marginatus, Coscinodiscus
- Maries' fir
- mariesii, Davallia
- mariesii, Abies
- marmoratum, Acer mono
- Marten
- martensi, Acirsa
- martensi, Mitrella
- Martes, genus
- Martes ten
- Martinia, genus
- martini, Siphonodendron
- Martinottiella, genus
- masou, Oncorhynchus masou
- masou subsp. ishikawae, Oncorhynchus
- masou subsp. masou, Oncorhynchus
- Massilina inaequalis
- masudae, Fulgoraria
- Masudapecten, genus
- Masudapecten iwasakiensis
- Masudapecten kintaichiensis
- masuiae, Toyamasauripus
- matajiroi, Anodonta
- matajiroi, Opalia
- matsubaishi, Monodiexodina
- matsubaishi, Parafusulina
- matsumoriensis, Glycymeris
- matsumoriensis, Miyagipecten
- matsumotoi, Mimarcaria
- matsumotoi, Pitar
- matsumurae, Acer palmatum
- matsuraensis, Callista
- matsushimai, Kranaosphinctes
- matsushimai, Perisphinctes
- matumoriensis, Glycymeris
- matumoriensis, Mizuhopecten
- matumori, Neptunea
- matumori, Neptunea hukusimensis
- matusimanus, Decorifer
- Maule's quince
- Mauremys, genus
- Mauremys nipponica
- Mauremys sinensis
- Mauremys yabei
- maxima, Lutraria
- maximoviczianoides, Tilia
- maximowicziana, Betula
- maximowiczianum, Acer
- maximowiczi, Calosoma
- maximowiczii, Alnus
- maximowiczii, Cerasus
- maximowiczii, Artemisia indica
- maximowiczii, Cerasus
- maximowiczii, Crataegus
- maximowiczii, Picea
- maximowiczii, Prunus
- maximowiczii, Trapa
- Mayfly
- Meandrarea somaensis
- Mediterranean mussel
- Medusozoa, subphylum
- Meekella gigantea
- meeki, Ariosoma
- Meekoceras, genus
- Meekoceras japonicum
- Meekoceras onoi
- Megabalanus rosa
- Megacardita, genus
- Megacardita cipangoana
- Megacardita ferruginosa
- Megacardita ommaensis
- Megacardita panda
- megacinerea, Juglans
- megacinerea, Juglans cinerea var.
- Megaloceros giganteus
- Megalodon, genus
- megalodon, Carcharocles
- megalodon, Carcharodon
- Megalophaedusa, genus
- megamiensis, Turbo
- Megangulus, genus
- Megangulus venulosus
- Megangulus zyonoensis
- megaphylla, Hamamelis japonica
- megaphyllus, Zamites
- megasamarum, Acer
- megaspira magna, Fulgoraria
- megaspira prevostiana, Fulgoraria
- Megayoldia, genus
- Megayoldia (Hataiyoldia) tokunagai
- Megayoldia (Hataiyoldia) tokunagai var. hayasakai
- Megayoldia japonica
- Megayoldia lischkei
- Megayoldia thraciaeformis
- Megayoldia tokunagai
- Megayoldia tokunagai var. hayasakai
- Megayoldia toyamaensis
- Megopis (Aegosoma) sinica
- Megopis sinica
- Meimuna protopalifera
- meisensis, Euspira
- meisensis, Polinices
- Melanoides vulgaris
- Meles, genus
- Meles anakuma
- Meles leucurus kuzuüensis
- Melia azedarach
- Melolontha, genus
- Melongena, genus
- Melonis, genus
- Melonis barleeanus
- Melonis pompilioides
- Melosira, genus
- Melosira distans
- Melosira granulata
- Melosira granulata var. angustissima
- Melosira islandica f. helvetica
- Melosira solida
- Melosira sulcata
- membranaceae, Lindera umbellata
- membranacea, Lindera
- membranaceum, Benzoin
- menardii, Globorotalia
- Menephiloides minensis
- meniscoides, Clathropteris
- Menuites sutneri
- Menyanthes, genus
- Menyanthes trifoliata
- Mercenaria, genus
- Mercenaria chitaniana
- Mercenaria sigaramiensis
- Mercenaria stimpsoni
- Mercenaria y-iizukai
- Mercenaria yiizukai
- Mercenaria yokoyamai
- Meretrix, genus
- Meretrix arugai
- Meretrix lamarckii
- Meretrix lusoria
- Meretrix meretrix
- meretrix, Meretrix
- Meretrix ninohensis
- Merica asperella
- Merisca capsoides
- Meropesta, genus
- Meropesta capillacea
- Mertensia pterocarpa var. yezoensis
- Mertensia sibirica
- Mesocibota bistrigata
- Mesocorbicula tetoriensis
- Mesodermochelys, genus
- Mesophyllum, genus
- Mesopuzosia, genus
- mesothunbergii, Pinus
- Metacarcinus izumoensis
- Metalimnobia quadrimaculata
- Metanothosaurus nipponicus
- Metapolygnathus abneptis
- Metasequoia, genus
- Metasequoia disticha
- Metasqualodon, genus
- Metasequoia japonica
- Metasequoia occidentalis
- Metriolepis kuzuensis
- Metroperiella montferrandii
- metternichii var. pentamerum, Rhododendron
- meyendorffi, Cheloniceras
- Micantapex luhdorfi
- Michelinia, genus
- Michelinia multitabulata
- Michelinoceras hidense
- Micrabacia fungulus
- Micrabacia japonica
- micranthum, Acer
- micra, Timoclea
- micra, Veremolpa
- microcarpa, Fagus
- microcarpa, Styrax
- microcarpha, Styrax
- microcephalus, Pterostichus
- Microcirce, genus
- microphthalma, Cyphastrea
- microphylla, Alnus tinctoria
- microphylla, Buxus
- microphylla var. japonica, Buxus
- microphyllum, Acer sieboldianum
- microsiratori, Siratoria
- microsiratori, Tapes
- Microsolena, genus
- Micostomatidae, family
- Microstomus tochigiensis
- microstriata, Chlorostoma
- microstriata, Tegula
- Microtus, genus
- middendorfii, Buccinum
- Middendorf's whelk
- miensis, Saccella
- miensis, Stegodon
- miensis, Trionyx
- mifunensis, Trigonioides
- mifunensis, Trigonioides (Kumamotoa)
- Mikadotrochus, genus
- Mikadotrochus yoshiwarai
- mikasaensis, Taniwhasaurus
- mikii, Elaeagnus
- mikii, Pinus
- Miliolinella circularis
- Milleporidium, genus
- Millerella, genus
- Millerella yowarensis
- Milletia notoensis
- miltoni, Oulangia stokesiana
- Mimachlamys, genus
- Mimachlamys asperulata
- Mimachlamys kaneharai
- Mimachlamys satoi
- Mimarcaria matsumotoi
- minatoi, Alpinoschwagerina
- minatoi, Carbonoschwagerina
- minatoi, Pseudoschwagerina
- minensis, Menephiloides
- minensis, Neocalamites
- Minesedes elegans
- Minetaxites ushioi
- Minetrigonia, genus
- Minetrigonia hegiensis
- Minetrigonia hegiensis hegiensis
- Minetrigonia katayamai
- minikoiensis, Leptoseris
- minimus, Ipsvicioides
- Miniopterus, genus
- Minke whale
- minoensis, Amphitragulus
- minoensis, Apollon
- minoensis, Astriclypeus
- minoensis, Astriclypeus mannii
- minoensis, Aturia
- minoensis, Aviculopecten
- minoensis, Barbatia
- minoensis, Cardita
- minoensis, Echinarachnius
- minoensis, Enteletes
- minoensis, Gyrineum
- minoensis, Hiatula
- minoensis, Kewia
- minoensis, Nassarius
- minoensis, Naticopsis
- minoensis, Neoschwagerina
- minoensis, Phos
- minoensis, Soletellina
- minoensis, Stromatopora
- minoensis, Turbo
- minoensis, Zeuxis
- Minojapanella, genus
- Minolia, genus
- Minolia subangulata
- Minolia tsukiyoshiensis
- minor, Apiotrigonia
- minor, Conchocele compacta
- minores, Epithemia adnata
- minores, Epithemia zebra
- minor, Parasphenophyllum, thonii var.
- minor, Smilax
- minuta, Acila
- minuta, Echinarachnius
- minuta, Fabulina
- minuta, Kewia
- minuta, Liocyma
- minuta, Nitidotellina
- minuta, Siphonalia
- minuta, Timoclea
- minuta, Veremolpa
- Minute black scavenger fly
- minutoides, Acila
- minutoserratus, Cancer
- miocathayensis, Carya
- Miocenehadra mizunamiensis
- miocenica, Carpinus
- miocenica, Picea
- miocenica, Pinus
- miocenica, Tsuga
- miocenicus, Sapindus
- miocenum, Cinnamomum
- miochinensis, Pistacia
- Miocidaris, genus
- Miocidaris spinulifera
- miocuspidata, Castanopsis
- miodelicatula, Littoraria
- miodelicatula, Littorinopsis
- Miodontiscus nakamurai
- Miodontiscus prolongatus
- Miodontiscus prolongatus nakamurai
- miofloribunda, Berchemia
- mioformosana, Entada
- Miogypsina, genus
- Miogypsina kotoi
- Miogypsina kotoi kotoi
- miohenryi, Acer
- miojaponica, Alnus
- miojaponica, Sophora
- miokaki, Diospyros
- miokalkora, Albizia
- miokalkora, Albizzia
- miomaximowicziana, Betula
- miomollissima, Castanea
- miopumila, Ulmus
- Miosesarma naguraense
- miosinensis, Gleditsia
- miosinica, Liquidambar
- miostellatus, Platichthys
- miosuccedanea, Rhus
- mioturczaninovii, Carpinus
- miovariabilis, Quercus
- miowalteri, Cornus
- miqueliana, Tilia
- mirabilis, Acila
- mirabilis, Echinarachnius
- mirabilis, Nipponites
- mirabilis, Scaphechinus
- Mirugai clam
- Misellina, genus
- Mite
- Mitra, genus
- Mitra ebenus
- Mitra kurakiensis
- Mitra shell
- Mitrella, genus
- Mitrella bicincta
- Mitrella burchardi
- Mitrella lischkei
- Mitrella martensi
- Mitrella tenuis
- Mitrella yabei
- Mitre shell
- Mitridae, family
- mitsuganoense, Periploma
- mitsuganoensis, Cardiomya
- miurensis, Chlamys
- miyabeana supsp. gilgiana, Salix
- miyabei, Acer
- Miyabe maple
- miyagiensis, Glycymeris
- Miyagi oyster
- Miyagipecten matsumoriensis
- miyakoense, Petrophyton
- miyakoense, Tylostoma
- Miyama cherry
- miyamurensis, Ruditapes
- miyatai, Cuora
- miyatai, Cyclemys
- miyatensis, Arca
- miyatensis, Exotica
- miyatensis, Fabulina
- miyatensis, Ophiodermella
- miyatensis, Semelangulus
- miyatokoensis, Chlamys
- miyatokoensis, Dallina
- Mizuhobaris izumoensis
- Mizuhopecten, genus
- Mizuhopecten chichibuensis
- Mizuhopecten hokurikuensis
- Mizuhopecten ibaragiensis
- Mizuhopecten kagamianus
- Mizuhopecten kintaichiensis
- Mizuhopecten kimurai
- Mizuhopecten kimurai murayamai
- Mizuhopecten kimurai nakosoensis
- Mizuhopecten kimurai ugoensis
- Mizuhopecten (Kotorapecten) kagamianus
- Mizuhopecten (Kotorapecten) kintaichiensis
- Mizuhopecten matumoriensis
- Mizuhopecten paraplebejus
- Mizuhopecten planicostulatus
- Mizuhopecten tokyoensis
- Mizuhopecten tokyoensis hokurikuensis
- Mizuhopecten tokyoensis sematensis
- Mizuhopecten tryblium
- Mizuhopecten yamasakii
- Mizuhopecten yessoensis
- Mizuhopecten yessoensis yokoyamae
- Mizuhopecten yokoyamae
- mizunamiensis, Batillaria
- mizunamiensis, Miocenehadra
- mizutanii, Parafusulina
- mizuyagadaniensis, Corwenia
- mizuyagadaniensis, Huangia
- Mizzia, genus
- Mizzia velebitana
- Mizzia yabei
- mochigarei, Lepidopsetta
- mochizukii, Lucinoma
- modesta, Neptunea
- modesta, Searlesia
- modificata, Siphonalia
- modiolaeforme, Trapezium
- Modiolus, genus
- Modiolus arakawensis
- modiolus, Brachidontes
- modiolus difficilis, Modiolus
- Modiolus elongatus
- Modiolus kurilensis
- Modiolus maedae
- Modiolus margaritaceus
- Modiolus modiolus difficilis
- mogamiensis, Ancistrolepis
- mogamiensis, Buccinum
- Mogera imaizumii
- Mohnia yanamii
- Mohnia yanamii tenuis
- mojsisovicsi, Chlamys
- mojsisovicsi, Oxytoma
- Molobratia japonica
- Molopopholus nipponicus
- monadelpha, Stewartia
- Monarch birch
- Mongolian poplar
- mongolica subsp. crispula, Quercus
- mongolica var. grosseserrata, Quercus
- Monia macrochisma
- Monia macrochisma ezoana
- moniliferum, Suchium
- moniliferum, Umbonium
- Monilophytes
- moniwaensis, Conus
- moniwaensis, Kotorapecten
- moniwaensis, Kotorapecten kagamianus
- moniwaensis, Patinopecten kagamianus
- moniwensis, Cornucoquimba
- mono, Acer
- mono, subsp., Acer pictum
- Monodiexodina, genus
- Monodiexodina matsubaishi
- mono var. glaucum, Acer
- Mono maple
- mono var. marmoratum, Acer
- Monomyces rubrum
- Monophyllites, genus
- Monophyllites wengensis
- Monoplex parthenopeus
- Monotis, genus
- Monotis (Entomonotis), subgenus
- Monotis (Entomonotis) ochotica
- Monotis (Entomonotis) ochotica var. densistriata
- Monotis (Entomonotis) ochotica var. eurachis
- Monotis ochotica
- Monotis ochotica var. densistriata
- Monotis ochotica var. eurachis
- Monotygma, genus
- Monotygma eximia
- Montane alder
- Montastrea curta
- montferrandii, Codonellina
- montferrandii, Metroperiella
- Montipora verrilli
- Montlivaltia, genus
- Moon snail
- morikawai, Carbonoschwagerina
- morikawai, Pseudoschwagerina
- morozakiensis, Lepidopleurus
- Morus, genus
- Morus australis
- Morus bombycis
- Mosasaurus, genus
- Moschus, genus
- Mosquito
- Moss animal
- motidukii, Turritella saishuensis
- Mountain hawk-eagle
- Mourlonia hayasakai
- Mouse-eared bat
- Mouse keyhole limpet
- Mucuna, genus
- Mucuna chaneyi
- Mulberry
- Müller's nut clam
- multicostata, Astarte
- multicostata, Ectomaria
- multicostata, Solenospira
- multiflora, Rosa
- multiformis, Batillaria
- multiformis, Eumorphotis
- multigranosa, Biwamelania
- multigranosa, Semisulcospira
- multiseptata, Lepidolina
- multiseptata shiraiwensis, Lepidolina
- multiseptata, Yabeina
- multispinosum, Trachycardium
- multispinosum, Vepricardium
- multistriata, Pterocarya
- multitabulata, Michelinia
- Multituberculata, order
- munda, Glycymeris
- munda, Tucetonella
- Munida, genus
- Munidopsis, genus
- munitum, Archaeohagiastrum
- Muraenesocidae, family
- muratai, Neoschwagerina
- murayamai, Mizuhopecten kimurai
- murayamai, Palliolum
- Murchisonia, genus
- Murchisonia yabei
- Murex snail
- muricatum, Myriophyllum spicatum
- Muricidae, family
- Murina, genus
- muroii etomoensis, Cristaria
- murrhina, Pyrgo
- Musa, genus
- Musashia striata
- Musashia yanagidaniensis
- musashiensis, Acila
- musasiensis, Granulifusus
- Muscomorpha, infraorder
- Musculista, genus
- Musculus, genus
- mus, Diodora
- Musk deer
- Musophyllum nipponicum
- Mustela erminea
- mutica, Fulvia
- mutsuana, Cancellaria
- Mya, genus
- Mya arenaria
- Mya arenaria oonogai
- Mya (Arenomya) grewingki
- Mya (Arenomya) grewingki var. elongata
- Mya cuneiformis
- Myadora fluctuosa
- Myadora ikebei
- Myadora japonica
- Myadora suzuensis
- Mya grewingki
- Mya grewingki var. elongata
- myagroides, Myagropsis
- Myagropsis myagroides
- Mya japonica
- Mya oonogai
- Mya pseudoarenaria
- Mya uzenensis
- Mycetophilidae, family
- mycetoseroides, Leptoseris
- Myctophidae, family
- Myliobatis, genus
- Myliobatis tobijei
- Myochoncha, genus
- myogadaniensis, Cyclocardia
- Myophorella orientalis
- Myophoria, genus
- Myophoria japonica
- Myopus schisticolor
- Myotis genus
- Myrene (Mesocorbicula) tetoriensis
- Myrene tetoriensis
- Myrica, genus
- Myricaceae, family
- Myriophyllum spicatum
- Myriophyllum spicatum var. muricatum
- myrsinaefolia, Quercus
- myrsinifolia, Quercus
- Mysticeti, superfamily
- mysticum, Suchium
- mysticum, Umbonium
- Mytilisepta keenae
- Mytilus, genus
- Mytilus coruscus
- Mytilus crassitesta
- Mytilus galloprovincialis
- Mytilus giganteus
- Mytilus grayanus
- Mytilus tichanovitchi
- Mytilus (Tumidimytilus) tichanovitchi
- Mytilus unguiculatus