Isohypsibius

Class : Eutardigrada

Order : Isohypsibioidea

Family : Isohypsibiidea

Genus : Isohypsibius

Genus Isohypsibius

Isohypsibioidea from Marley et al. 2011: “Parachela. Claws asymmetrical (2121); Isohypsibius-type claw pairs; AISM ridged.”

Isohypsibioidea from Bertolani et al. 2014: “Double claws asymmetrical with respect to the median plane of the leg (2121), normally with similar shape and size on each leg; double claws of the Isohypsibius type (secondary branch of the external claw inserted perpendicularly on the claw basal tract), or reduced from it: Hexapodibius type (very short, without common basal tract, with a base as large as the sum of the primary and secondary branch widths, and with an evident suture between primary and secondary branch); Haplomacrobiotus type (one branch only); completely absent (Apodibius). Buccal tube completely rigid (apart Paradiphascon; see below) and often relatively large, without (Dastychius, Eremobiotus, Halobiotus, Isohypsibius, Paradiphascon, Pseudobiotus, Thulinius) or with (Apodibius, Doryphoribius, Haplomacrobiotus, Haplohexapodibius, Hexapodibius, Parhexapodibius) ventral lamina. Eggs with smooth shell laid within the exuvium.”

Isohypsibiidae from Marley et al. 2011: “Isohypsibioidea. Claw pairs of similar size and shape. External and internal claws exhibiting articulation (the basal section and secondary branch form a solid unit while the primary branch and secondary branch articulate). Claws Isohypsibius-type, forming a right-angle between basal section and secondary branch. AISM ridge-like.”

Genus description from Thulin 1928: “Krallen vom zweiten Typus. Für die von mir beobachteten Arten gilt ferner, dass die Muskelfortsätze am vorderen Teile der Mundröhre crista-förmig sind (bei undulatus, septentrionalis und Sattleri konnte dies jedoch nicht sicher festgestellt werden). Weiter ist bei ihnen der hinter dem vierten Bauchganglion inserierende Transversalmuskel jeder Seite einfach oder aus 2-3 dicht aneinander verlaufenden Strängen zusammengesetzt; eine Ausnahme bildet indessen I. septentrionalis, bei welchem wie bei den Macrobiotiden der anderen Gattungen dieser Muskel in zwei Stränge geteilt ist, welche lateral entfernt voneinander entspringen.”

Translation: Claws of the second [Isohypsibius] type. For the types I have observed, the muscular processes on the anterior part of the buccal tube are also crista-shaped (however, this could not be ascertained with undulatus, septentrionalis and sattleri). Further, in them, the transverse muscle of each side, inserting behind the fourth abdominal ganglion, is composed simply or of 2-3 strands running close to each other; an exception, however, is I. septentrionalis, in which, as in the Macrobiotids of the other genera, this muscle is divided into two strands which emerge laterally apart from each other.

Genus description from Schuster et al. 1980: “Six peribuccal lobes present; buccal lamellae absent. Buccal tube short, rigid, without spiraled thickenings. Pharynx with apophyses, macroplacoids or macro- and microplacoids; without septulum. Two double claws of each leg of similar size and shape; not connected; without lunulae. Primary branch of external double claw flexible at junction with secondary; sequence of branches 2,1,2,1. Cuticular thickenings (bars) sometimes developed near base of internal double claws, or between internal and external claws. Smooth eggs deposited in cuticle.”


   

I. tuberculatis group”: Which ones? Defined as having dorsal gibbosities. From Ramazzotti & Maucci key: tuberculatus, hadzii, verrucosus, montanus, indicus, nodosus, josephi, duranteae, neoundulatus, pratensis, bartosi, rudescui, theresiae, pappi, dudichi, franzi, papillifer, vejdovskyi, sattleri, brevispinosus, gyulai, helenae, mamillosus, septentrionalis, cameruni, truncorum, novaeguineae, elegans, gracilis, torulosus, austriacus, eplenyiensis, silvicola, basalovoi, latiunguis, leithaicus, tubercoloides, pilatoi, bulbifer, hypostomoides, glaber, mihelcici, lunulatus, cyrilli, belliformis, ronsisvallei, effusus

Thulin (1928) also had undulatus, and rollei (but that’s Macrobiotus)

Prosostomus group (Thulin) (Elongated body with short limbs. Body wall smooth. Claws moderately large.): schaudinni, prosostomus, canadensis. Check arbiter, which has very very fine sculpting but otherwise resembles prosostomus.

Annulatus group (Thulin) (Elongated body with long legs. Skin smooth or provided with small warts. Large to very large claws.) annulatus, asper, granulifer, megalongx (but now Pseudobiotus), tetradactyloides, augusti (now Thulinius?), appelofi (now Halobiotus)

granulifer group (Tumanov 2003) (sculptured, 300): asper, baicalensis, baldii, baldiioides, brulloi, campbellensis, granulifer, irregibilis, kenodontis, kotovae, ladogensis, laevis, marii, monoicus, palmai, pushkini, rugosus, tubereticulatus, wilsoni

Cheat sheet:
lunulatus: 2-0-0
sattleri: 2-0-0
tuberculatus: 2-0-0
n sp 1: 2-0-0, 1st 2x 2nd
n sp 3: 2-0-0, 1st=2nd
n sp 2: 2-1-0
cf basalovoi: 3-0-0
“mesh” n sp: 3-0-0
granulifer: 3-0-0
cf deconincki: 3-0-0
cf brevispinosus: 3-0-0
n sp 4: 3-0-0, large gap etween 2 & 3
n sp 5: 3-0-0, 123 equidistant
baldii: 3-0-0, 2,2,1
saracenus: 2-0-0, indented (actually Mixibius)

Alberta:
cf tuberculatus

Canada:
canadensis (Murray, 1910) smooth (but sometimes small papillae in caudal region). Eyed. Up to 225um. 3 granular or short rod macrop, increasing length from 1 to 3! Macrop I very close to & parallel to lumen of pharynx, macrop row diverges somewhat, caudally. Microp indistinct or lacking. Characteristics to distinguish from prosostomus & schaudinni: arrangement & shape of macrp, straight bt, long & slender primaries of claws IV.
chiarae Maucci, 1987 (reported as Isohypsibius bertolanii) smooth
granulifer granulifer Thulin, 1928 (reported as granulifer) 3-0-0
lunulatus (Iharos, 1966)
papillifer bulbosus (Marcus, 1928) 3-0-0
papillifer papillifer (Murray, 1905) (reported as papillifer) 3-0-0
prosostomus prosostomus Thulin, 1928 (reported as prosostomus) smooth (almost always) or faintly granulated (rare). Adult length 270 to 470um. Eyes. bt 3-5um wide. 310. 1st macrop almost touching apophyses, 2nd ~= 1st and touching, 3rd a little shorter than 1+2. Cuticular bars under I-III primaries.
sattleri (Richters, 1902) [Hypsibius bakonyiensis Iharos, 1964] even # of gibs
schaudinni (Richters, 1909) 3-1-0 or 3-0-0. Up to 368um. Eye spots. bt diameter about 3um. macrop oval granules, increasing in size caudally. To distinguish from prosostomus: in schaudinni buccal aperture is a bit ventral, whereas terminal (with straight bt) in prosostomus; macrop length (1<2<3, but in prosostomus 1 ~= 2 < 3) pharynx length width ratio (1.1-1.2 : 1, in prosostomus is 1.2-1.3 : 1) – but also, in at least some cases, schaudinni lacks cuticular bar (or all cases? R&M unclear)
tetradactyloides (Richters, 1907) 3-0-0, very narrow bt Freshwater
tuberculatus (Plate, 1888) even # of gibs except at ant/post
woodsae Kathman, 1990 2-0-0, even # of gibs in each row

North America / Nearctic:
baldii (Ramazzotti, 1945) 3-0-0
cf basalovoi 3-0-0
“mesh” n sp 3-0-0
brevispinosus (Iharos, 1966) 3-0-0
deconincki Pilato, 1971 3-0-0
granulifer (subsp. not specified?) 3-0-0 Freshwater
n species 1 2-0-0, 1st 2x 2nd
n species 2 2-1-0
n species 3 2-0-0, 1st = 2nd
n species 4 3-0-0, large gap between 2 & 3
n species 5 3-0-0, equidistant

Other:
altai Kaczmarek & Michalczyk, 2006
annulatus annulatus (Murray, 1905) Freshwater
annulatus minor (Ramazzotti, 1945)
arbiter Binda, 1980 Possibly hard-to-see sculpting, most pronounced caudally from around legs III, but extends at least to II. 310, micro is small & thin. Small lunules, and cuticular bars beneath primaries of I-III. Lunules more developed & cuticular bars shorter than prosostomus: for claw I: ~50% of length of internal claw, and 13-17% of bt length, compared to 67% & 20% in prosostomus, more info in binda 1980.
archangajensis Kaczmarek & Michalczyk, 2004
arcuatus (Bartoš, 1934)
asper (Murray, 1906)
austriacus (Iharos, 1966)
baicalensis (Ramazzotti, 1966)
baldiioides Tumanov, 2003
barbarae Pilato & Binda, 2002
bartosi (Iharos, 1966)
basalovoi (Durante & Maucci, 1973)
belliformis (Mihelcic, 1971)
bellus (Mihelcic, 1971)
borkini Tumanov, 2003
brevitubulatus Rho, Chang & Kim, 1997
brulloi Pilato & Pennisi, 1976
bulbifer (Mihelcic, 1957)
cameruni (Iharos, 1969)
campbellensis Pilato, 1996
ceciliae Pilato & Binda, 1987
changbaiensis Yang, 1999
costatus (Mihelcic, 1971)
coulsoni Kaczmarek, Zawierucha, Smykla & Michalczyk, 2012
cyrilli (Mihelcic, 1951)
damxungensis Yang, 2007
dastychi Pilato, Bertolani & Binda, 1982
deflexus (Mihelcic, 1960)
dudichi (Iharos, 1964)
duranteae (Maucci, 1978)
effusus (Mihelcic, 1971)
elegans Binda & Pilato, 1971
eplenyiensis (Iharos, 1970)
franzi (Mihelcic, 1951)
fuscus (Mihelcic, 1971/72)
gilvus Biserov, 1986
glaber (Durante Pasa & Maucci, 1979)
glazovi Biserov, 1999
gracilis (Iharos, 1966)
granditintinus Chang & Rho, 1996
granulifer koreanensis (Iharos, 1971)
gyulai (Mihelcic, 1971)
hadzii (Mihelcic, 1938)
helenae (Iharos, 1964)
hydrogogianus Ito & Tagami, 1993
hypostomoides (Mihelcic, 1971)
improvisus Dastych, 1984
indicus (Murray, 1907)
irregibilis Biserov, 1992
jakieli Dastych, 1984
jingshanensis Yang, 2003
jinhouensis Yang, 2007
josephi (Iharos, 1964)
kenodontis Kendall-Fite & Nelson, 1996
kotovae Tumanov, 2003
kristenseni Pilato, Catanzaro & Binda, 1989
ladogensis Tumanov, 2003
laevis McInnes, 1995
latiunguis (Iharos, 1964) most rows even
leithaicus (Iharos, 1966)
liae X. Li & L. Wang, 2006
lineatus (Mihelcic, 1969)
longiunguis Pilato, 1974
macrodactylus (Maucci, 1978) [zierhofferi Dastych, 1980] malawiensis Jørgensen, 2001
mammillosus (Iharos, 1964)
marcellinoi Binda & Pilato, 1971
marii R. Bertolani, 1982
mihelcici (Iharos, 1964)
monoicus R. Bertolani, 1982
monstruosus Maucci, 1991
montanus Mihelcic, 1938
myrops (du Bois-Reymond Marcus, 1944)
neoundulatus (Durante Pasa & Maucci, 1975)
nipponicus Sudzuki, 1975
nodosus (Murray, 1907)
novaeguineae (Iharos, 1967)
palmai Pilato, 1996
panovi Tumanov, 2005
papillifer indicus (Iharos, 1969)
pappi (Iharos, 1966)
pauper (Mihelcic, 1971)
pilatoi (Durante Pasa & Maucci, 1979)
pratensis (Iharos, 1964)
prosostomus cambrensis (Morgan, 1976)
pseudoundulatus (da Cunha & do Nascimento Ribeiro, 1964)
pulcher (Mihelcic, 1971/72)
pushkini Tumanov, 2003
qinlingensis X. Li, L. Wang & Yu, 2005
rahmi X. Li & L. Wang, 2006
reticulatus Pilato, 1973
roberti Biserov, 1996
ronsisvallei Binda & Pilato, 1969 1st & last rows even
rudescui (Iharos, 1966)
rugosus Guidi & Grabowski, 1996
sabellai Pilato, Binda, Napolitano & Moncada, 2004
sculptus (Ramazzotti, 1962)
sellnicki (Mihelcic, 1962)
septentrionalis Thulin, 1928
silvicola (Iharos, 1966)
sismicus (Maucci, 1978)
solidus (Mihelcic, 1971)
taibaiensis X. Li & L. Wang, 2005
theresiae (Iharos, 1964)
torulosus (Mihelcic, 1959)
truncorum (Iharos, 1964)
tuberculoides (Mihelcic, 1951)
tubereticulatus Pilato & Catanzaro, 1989
tucumanensis Claps & Rossi, 1984
undulatus Thulin, 1928
vejdovskyi (Bartoš, 1939)
verae Pilato & Catanzaro, 1989
verrucosus (Della Valle, 1915) [gibbus (Marcus, 1928)] wilsoni (Horning, Schuster & Grigarick, 1978)
yunnanensis Yang, 2002

Key from Ramazzottius & Maucci (1983):
1. Cuticle smooth, without sculpture, swellings, or gibbosities ………….. 2
Cuticle sculptured, with swellings and/or with gibbosities ………….. 20
2 (1). Lunule present ………………………………………. 3
Lunule absent ………………………………………. 7
3 (2). Three macroplacoids are present ………………………….. 4
Two macroplacoids are present ……………………………. 6
4 (3). The claws of the 4th pair of legs are considerably greater than the others . . . . . . . . . . . . . . . . . . . . . . . . . I. macrodactylus
The claws of the 4th pair of legs are not greater than the others . . . . . . . . . 5
5 (4). Macroplacoids in the shape of rods, of which the 3rd is longest; principal branch of the claws with accessory points . I. sultursus NOW THULINIUS
Macroplacoids very short, the first two almost granules, a little elongated; lacking accessory points . . . . . . . . . . . . . . . . . . . . . . . . . . . I. deconincki
6 (3). Lunule smooth; normal claws of the Isohypsibius type . . . . . . . . I. marcellinoi
Lunule dentate; claws of the 4th pair have branches fused for a good part and divergent at 18Oµm so that the claws form almost a triangle . . . . . . . . . . . . . . . . . . . . . . . . . . I. alicatai
7 (2). The claws of each leg are considerably different, only the internal claws (smaller) are clearly of the Isohypsibius type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Normal claws, both of the Isohypsibius type . . . . . . . . . . . . . . . . . . . . . . . . 9
8 (7). The external claw has the principal branch not connected with the basal and secondary branch . . . . . . . . . . . I. deflexus
In the external claw, the principal branch is connected with the secondary, but it is extremely long, slender, bristle-like . . . . . . . . . . . . . . I. renaudi NOW RAMAJENDAS
9 (7). There are two macroplacoids, with microplacoid ……………….. 10
There are three macroplacoids present ……………………… 12
10 (9). The two macroplacoids are close to each other even touching so as to simulate a single placoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. nipponicus
The two macroplacoids are clearly distinct . . . . . . . . . . . . . . . . . . . . . . . . 11
ll(10). The first macroplacoid is almost twice as long as the second; basal branch oftheclawisshort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. solidus
The first macroplacoid is less than one and a half the second; basal branch long . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. saracenus
12 (9). Microplacoid present …………………………………. 13
Microplacoid absent ………………………………….. 16
13(12). Not marine; macroplacoids granules, very little elongation; cuticular bar in legs 1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. prosostomus
Marine; macroplacoids rodlike; without a cuticular bar in the legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
14(U). Diameter of the buccal tube 1.5µm; first macroplacoid shorter than the second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. stenostomus
Diameter of the buccal tube 3µm; first macroplacoid longer than second . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
l5( 14). The second macroplacoid is shorter than the third . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. appelloefi NOW HALOBIOTUS STENOSTOMUS (marine?)
The second macroplacoid is equal or longerthanthethird . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I.geddesi ALSO NOW HALOBIOTUS STENOSTOMUS (marine?)
16(12). The principal branch of the external claw is not connected with the basal and secondary branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. deflexus
Branches of the claws are connected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
17(16). Claws of each leg almost equal, very long, macroplacoids very short, almost granules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. tetradactyloides
Clawsofeachlegofdifferentsize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
18(17). Mouth anterior; apophyses almost absent; macroplacoids rod-like . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. myrops
Macroplacoids short, oval granules; apophyses obvious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
19(18). The macroplacoids are granules almost equal, increasing from 1st to 3rd with divergent positions; principal branch of the external claw very long and slender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. canadensis
The macroplacoids are oval granules; principal branch of the claws robust . . . . . . . . . . . . . . . . . . I. schaudinni
20 (1). Cuticle with transverse swellings, without gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Cuticle with sculpture and/or with gibbosities . . . . . . . . . . . . . . . . . . . . . . 23
21(20). Three macroplacoids are present ……………………. I. arcuatus
Two macroplacoids are present …………………………… 22
22(21). There are 24 or more transverse swellings; macroplacoids short, the 1st longer than the 2nd; size less than 300µm . . . . . . . . . . . . . . . . . . . . . . . . . I. undulatus
Swellings less developed and less regular; first placoid almost double the second; size more than 4OOµm . . . . . . . . . . . . . . . . . . . . . . . . . I. pseudoundulatus
23(20). Cuticle sculptured, without gibbosities ………………………. 24
Cuticle with gibbosities ………………………………… 37
24(23). Cuticle wrinkled; 3 macroplacoids in the form of granules; accessory points only on the internal claw . . . . . . . . . . , . . . . . . . . . . . . . . . . . I. lineatus
Different . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
25(24). Sculpture composed of granules, without reticulated pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Sculpture with reticulated pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
26(25). Three macroplacoids are present …………………………. 27
Two macroplacoids are present …………………………… 28
27(26). The sculpture is a fine granulation; the first two macroplacoids are almost in contact with each other; basal branch oftheclawsratherlong . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. granulifer
The sculpture is composed of hemispherical tubercles; basal branch of the claws shorter . . . . . . . . . . . . . . . . I. asper
28(26). The macroplacoids (at least the 1st) are rod-like, considerably longer than wide . . . . . . . . . . . . . . . . . . . . . . . 29
The macroplacoids are short and stumpy rods, or else granules . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . 30
29(28). The granulation is composed of tubercles arranged in transverse rows; macroplacoids slender, equal; accessory points on the principal branch of the claw . . . . . . . . . . . . . . . . . . . . . . . . I. annulatus
The granulation is fine; the 1st placoid is three times longer than the second; claws without accessory points . . . . . . . . . . . . . . . . . . . . . . . . . . I. fuscus
30(28). The granulation covers only the caudal area; two granular macroplacoids, which do not reach the middle of the pharynx . . . . . . . . . . . . . . . . . . . . . . I. sellnicki
The granulation is extended over all the body . . . . . . . . . . . . . . . . . . . . . . 31
31(30). The granules are extremely fine, without order, present even on the ventral surface . . . . . . . . . I. sculptus
The granules are arranged in an ordered way to form a pattern; legs and ventral surface not sculptured . . . . . . . . . . . . . . . . . . . . . . . . . I. pauper
32(25). There are two macroplacoids ……………………………. 33
There are three macroplacoids …………………………… 35
33(32). The macroplacoids are very slender rods, the 1st of the three longer than the 2nd; microplacoid present . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. pulcher
The macroplacoids are short rods; microplacoid absent . . . . . . . . . . . . . . 34
34(33). Reddish-orange color; without lunule and bar in legs; moss-dwelling . . . . . . . . . . . . . . . . . . . . . . . . . . I.flavus NOW DORYPHORIBIUS CITRINUS?
Colorless; there is lunule and cuticular bar in the leg; aquatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. reticulatus
35(32). Lunule absent; sculpture of very fine granules, reticulated pattern seen with high magnification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. baldii
Lunule present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
36(35). Near the lst-3rd claws there is a cuticular bar …………….. I. brulloi
The cuticular bar is absent …………………………. I. wilsoni
37(23). The dorsal gibbosities are irregularly arranged, not aligned in transverse rows . . . . . . . . . . . . . . . . . . . . . . . 38
The gibbosities are arranged in transverse rows . . . . . . . . . . . . . . . . . . . . . 40
38(37). The gibbosities are low, irregular, with undulating profile; there is also a hexagonal sculpturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. hadzii
Different . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
39(38). Numerous gibbosities, hemispherical, in contact with others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. gibbus NOW I verrucosus
A few large gibbosities, others small, the last two, over the 4th legs, are covered with tubercles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. montanus
40(37). All the rows include an even number of gibbosities, in which there are no dorso-median gibbosities . . . . . . . . . . . . . . . . . 41
At least some rows have an odd number of gibbosities . . . . . . . . . . . . . . . 59
41(40). The gibbosities are small tubercles, arranged in about 24 transverse rows of 8 tubercles each . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. indicus
Gibbosities hemispherical, conical, or papilliform, arranged in 6-11 transverse rows . . . . . . . . . . . . . . . . . 42
42(41). All the gibbosities are hemispherical and not terminated in a point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Some gibbosities are conical, mammillary, or papillose, and terminated in a point or with a spine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
43(42). Other than the principal row of gibbosities (from 6 to 10), there are no secondary gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
There are secondary or lateral gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . 50
44(43). There is a cuticular bar in the legs, near the claws (N.B.! This detail is ignored by almost all authors; included here are only the species for which the bar is explicitly obvious) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
There is no bar, or it is not obvious . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
45(44). There are 7 transverse rows of gibbosities, of which the first five have 6 gibbosities, the last two have 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. nodosus
There are 9 transverse rows of 2 or 4 gibbosities each . . . . . . . . . . . . . . . . 46
46(45). The sculpture has a reticulated pattern; maximum size of 300µm . . . . I. josephi
The sculpture is composed of a coarse granulation, not reticulated; size up to or beyond 400µm . . . . . I. duranteae
47(44). Dorsum with transverse swellings and gibbosities (2 or 4) on the last six swellings; sculpture reticulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. neoundulatus
There are 9 or 10 rows of gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
48(47). Nine rows of gibbosities, the 3rd and the 4th rows have 6 gibbosities, the others 2 or 4; sculpture reticulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. pratensis
There are 10 rows, all with 2 or 4 gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
49(48). Only the 10th row has 2 gibbosities, all the others have 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. bartosi
There are 2 gibbosities in the rows 1,2,4, and 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. rudescui
50(43). Sculpture reticulated; there are 8 rows of gibbosities; there is also 4 lateral cylindrical papillae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. theresiae
There are 10 or 11 transverse rows of larger gibbosities; between these are inserted rows of smaller gibbosities; sculpture reticulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
51(50). Lunules are present; cuticular bars are present in the legs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. pappi
Lunules and bars absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. dudichi
52(42). All the gibbosities are elongated, conical, or mammillary, and have pointed apices . . . . . . . . . . . . . . . . . . . . . . . 53
Only part of the gibbosities have pointed apices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
53(52). The gibbosities (arranged in nine rows of 4 or 6 gibbosities each) are conical, pointed, and curved caudally . . . . . . . . . . . . . . . . . . . . . . . . . . . I. franzi
The gibbosities have hemispherical bases, which have papillae at their apices, most often elongated, spine-like . . . . . . . . . . . . . . . . . . . . . . . I. papillifer
54(52). The dorsal gibbosities are hemispherical, those lateral or dorsolateral are conical, pointed, or papilliform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Only the gibbosities of the caudal three rows are conical, pointed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
55(54). The cuticle is covered with small granules, sometimes transformed into spines; there are 10 transverse rows of gibbosities; the lateral gibbosities of rows 3-8 terminate with a short spine . . . . . . . . . . . . . . . . . . . . . . . . I. vejdovskyi
The sculpture is reticulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
56(55). There are 9 rows of gibbosities, each with 2 (6th row), 4, or 6 gibbosities, of which the lateral are pointed cones; reticulated sculpture somewhat coarse; lunule present . . . . . . . . . . . I. bakonyiensis NOW I sattleri
There are 10 rows of 4 or 6 gibbosities, of which the lateral are pointed; the caudal gibbosities are rounded with a short spine at the center . . . . . . . . . . . . . . . . . . . . . . . . I. brevispinosus
57(54). Granular sculpture; 11 rows of gibbosities, of which the last 3 have conical shape . . . . . . . . . . . . . . . . . . . . I. gyulai
Reticular sculpture; 8 or 10 rows of gibbosities . . . . . . . . . . . . . . . . . . . . . 58
58(57). Eight rows of 2 and 4 gibbosities alternating; those in the caudal region are conical . . . . . , . . . . . . . . . . . . . I. helenae
There are ten rows of 4 gibbosities each; the gibbosities of the last 3 rows are of mammillary form, pointed . . . . . . . . . . . . . . . . . . . . . . . I. mamillosus
59(40). All the rows have odd numbers of gibbosities, that is there is always a dorsomedian gibbosity . . . . . . . . . . . . . . . . . . 60
Only some of the rows have odd numbers of gibbosities . . . . . . . . . . . . . 63
60(59). Granular sculpture, not reticulated; 6-8 rows of gibbosities ………… 61
Reticulated sculpture; 8-9 rows of gibbosities …………………. 62
61(60). Six rows of 3 and 5 gibbosities alternating; 2 lateral gibbosities, smaller, anterior to the 1st row, another two posterior to the 6th . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. septentrionalis
Eightrowsof3or5gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . I. cameruni
62(6O). Eight rows of gibbosities (5 gibbosities in the lst-6th rows, 3 in the 7th-8th rows); lunule absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. truncorum
Nine rows of gibbosities (5 and 3 alternate in lst- 7th rows, 3 in the last two rows); lunule present . . . . . . I. novaeguineae
63(59). Only the first and/or the last row of gibbosities are of odd number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
There are more odd rows . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . 72
64(63). The first and the last rows are odd ………………………… 65
The first or the last row is odd …………………………… 68
65(64). There are lunules and cuticular bars inthelegs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Lacking lunules; granulate sculpture . . . . . . . . . . . . , . . . . . . . . . . . . . . . . 67
66(65). Reticulated sculpture; 1st and 10th rows with 5 gibbosities, others alternate 4 and 6, except the next to last (9th) which has only 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. tuberculatus
Granulated sculpture; row 1 with 3 gibbosities, last (10th) with only one; the other rows with 4 gibbosities each, except the 2nd which has 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . I. elegans
67(65). There is a cuticular bar in each leg; 1st and 10th rows with 3 gibbosities, all others with 4 . . . . . . . . . . . . . . I. gracilis
Without the bar in the legs; 1st and 9th rows with 3 gibbosities; 2nd-6th with 6, 7th-8th with 4, between rows of large gibbosities, there are small gibbosities . . . . . . . . . . . . I. torulosus
68(64). Only the first row is odd (3 gibbosities), the others (10 rows in all) have each 2 or 4 gibbosities; reticulated sculpture; lunules and bars in the legs . . . . . . . . . . . . . . . . . . . . . . . . . I. austriacus
Only the last row is odd, having 3 gibbosities . . . . . . . . . . . . . . . . . . . . . . 69
69(68). Lunules present; 9 or 10 rows of gibbosities ………………….. 70
Lunules absent; 8 or 9 rows of gibbosities ……………………. 71
70(69). Smooth cuticle between the gibbosities and on them; there are 9 rows, of which the last has 3 gibbosities, and the others alternate 2 and 4 . . . . . . . . . . . . . . . . . . . . . . . . . . I. eplenyiensis
Cuticle with reticulated sculpture; bar in legs; there are 10 rows of gibbosities, of which the last has 3, the 1st and sometimes the 2nd 2, and all others 4 . . . . . . . . . . . . . . . . . . . . . . . . . . I. silvicola
71(69). Nine rows of gibbosities, of which the last has 3, the others 2 or 4; reticulated sculpture; lacking bar in the legs . . . . . . . . . . . . . I. basalovoi
There are 8 rows of which the last has 3 gibbosities, the next to the last 2, all others 4; coelomic fluid violet . . . . . . . . . . . . . . . I. latiunguis
72(63). The gibbosities regularly alternate rows of odd and even rows ………. 73
The gibbosities do not alternate ………………………….. 74
73(72). Nine rows of gibbosities; granulated sculpture; lunules absent . . . . . . . . . . . . . . . . . . . . . . . . . I. vietnamensis NOW DORYPHORIBIUS VIETNAMENSIS
Ten rows of gibbosities; lunules present; bar in leg; reticulated sculpture . . . . . . . . . . . . . . . . . . . . . . I. leithaicus
74(72). There are 20 rows of gibbosities, the majority of which have even numbers . . . . . . . . . . . . . . . . . . . . . . I. tuberculoides
There are at maximum 12 rows of gibbosities . . . . . . . . . . . . . . . . . . . . . . 75
75(74). The 1st and the last row of gibbosities are odd, the others even; there are in all,10 rows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Arrangement different . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
76(75). Only the 8th and 9th are even (2-4 gibbosities), all others are odd; reticulated sculpture; there are no lunules; bar present in legs . . . . . . . . . . . . . . . . . . . . .I, pilatoi
The first 3 and the last 3 rows are odd, the other four rows have 4 gibbosities each . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. bulbifer
77(75). Sculpture composed of granules, increasing in an anterio-posterior sense; on the caudal end behind the 3rd pair of legs there are only 3 rows of gibbosities with respectively 3, 5, and 2 . . . . . . . . . . . . . . . . . . . . . I. hypostomoides
Different . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
78(77). Smooth cuticle; 9 rows of gibbosities, of which the 1st two include 2 gibbosities each, all the others 3; there is also a pair of lateral gibbosities …………………. . . . . . I. glaber
Different ………………………………… . . . . . . . . . 79
79(78). The first and last rows have odd (3) gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
The first and last rows have even (2 or 4) gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
80(79). Granulated sculpture; lunules absent; bars in legs; 8 rows of gibbosities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. mihelcici
Reticulated sculpture; 8 or 10 rows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
81 (80). Lunules present; bars in legs; 10 rows of gibbosities, of which the last 3 have 4, 4, 3; also lateral papillae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. lunulatus
There are 8 rows of gibbosities; the last three have 4, 3, 3; lunules absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. cyrilli
82(79). Granular sculpture, not reticulated; 9 rows of conical gibbosities, of which the last 4 have respectively 5,5, 2, 2 gibbosities . . . . . . . . . . . . I. belliformis
Reticulated sculpture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
83(82). There are 8 rows of hemispherical gibbosities; bars in legs . . . . . . . . . . . . . . . . . . . . . . . . . . . I. ronsisvallei
There are 12 rows of conical gibbosities . . . . . . . . . . . . . . . . . . . . . I. effusus


Citations :

Isohypsibius image from Tumanov DV. 2005. Isohypsibius panovi, a new species of Tardigrada from Ireland. Zootaxa. 812: 1-4.

“Parts” images Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Bertolani R, Guidetti R, Marchioro T, Altiero T, Rebecchi L, Cesari M. 2014. Phyloeny of Eutardigrada: New molecular data and their morphological support lead to the identification of new evolutionary lineages. Molecular Phylogenetics and Evolution. 76: 110-126.

Marley NJ, McInnes SJ, Sands CJ. 2011. Phylum Tardigrada: A re-evaluation of the Parachela. Zootaxa. 2819: 51-64.

Schuster RO, Nelson DR, Grigarick AA, Christenberry D. 1980. Systematic criteria of the Eutardigrada. Transactions of the American Microscopical Society. 99: 284-303.

Thulin G. 1928. Über die phylogenie und das system der tardigraden. Zoologisches Institut, Lund.

Claw Symmetry Relative To Median Plane Of Leg?

Image from Bingemer J, Hohberg K. 2017. An illustrated identification key to the eutardigrade species (Tardigrada, Eutardigrada) presently known from European soils. Soil Organisms. 89 (3): 127-149.

Stylet Support Insertion Point As Percentage Of Buccal Tube Length

Stylet support insertion point = ss divided by Buccal tube length, as %. Note anterior measurements begin at anterior margin of stylet sheaths, ss is centred where stylet supports reach buccal tube (this requires a good dorsal or lateral view for proper measurement)


Image from Tumanov DV. 2006. Five new species of the genus Milnesium (Tardigrada, Eutardigrada, Milnesiidae). Zootaxa. 1122: 1-23.

Buccal Tube Long, Mouth At Anterior Of A Protrusible Snout

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Pharyngeal Tube With Spiral Reinforcement

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Peribuccal papillae?

Note: in a tardigrade with snout extended, the flex of the pharyngeal tube may not be obvious.


Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

(Lateral) cephalic papillae, peribuccal papillae, Milnesiidae - type claws, exceptionally wide (and usually short) buccal tube?

Cephalic image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

Claw image modified from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Pharyngeal tube flexible?

Note: in a tardigrade with snout extended, the flex of the pharyngeal tube may not be obvious.


Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Serrated / dentate cuff / collar on legs IV

Left image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Right Image from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Leg sensory structures

Typically papilla on leg IV (se4 in image) and variable shape on leg I


Image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Trunk appendages

Appendages (after Cirrus A) labeled according to plate … B (Scapular plate), C (First segmental plate), D (Second segmental plate), E (terminal plate). “B” is lateral, “Bd” is dorsal

Be careful! There can be great variability within a population, with individuals (especially juveniles) lacking some appendages. When in doubt, choose “Unclear” to ignore this character!


Left image from Ramazzotti G, Maucci W. 1983. Il phylum Tardigrada(III edizione riveduta e aggiornata). English translation by C. W. Beasley, 1995. Memorie dell’ Istituto Italiano di Idrobiologia 41: 1-1012.

Right image cropped from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Cirrus A form

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Lower image (Mopsechiniscus) modified from du Bois-Reymond Marcus E. 1944. Sobre tardigrados brasileiros. Communicaciones Zoologicas del Museo de Historia Natural de Montevideo. 1(13): 1-19 plus plates.

Terminal / caudal plate with two notches?

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

First image (Echiniscus) modified from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Inner & outer buccal cirri present

Image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

Pseudosegmental plate between last medial plate & terminal plate?

Note on 2nd image, what you see before the terminal plate is either no plate, or a full-width medial plate; don’t confuse the latter with a pseudosegmental plate!
Also, sometimes the pseudosegmental plate is paired, like segmental plates II & III. It’s still pseudosegmental!

Images from Clifford HF. 1991. Aquatic invertebrates of Alberta. University of Alberta Press, Alberta, Canada.

Segmental plates larger than intersegmental?

Image modified from Lindahl & Balser (1999), http://www.iwu.edu/~tardisdp/Keypage35.html

Any Paired Plates?

Images from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335