Diphascon

Class : Eutardigrada

Order : Hypsibioidea

Family : Hypsibiidae

N/A

Subfamily Diphasconinae

Hypsibioidea from Pilato 1969 in Marley et al. 2011: “Parachela; claws asymmetrical (2121); Hypsibius-type claw pairs; AISM hooked (or, if the buccal tube is elongated, AISM can be broad ridges).” Hypsibioidea from Bertolani et al. 2014: “Double claws asymmetrical with respect to the median plane of the leg (2121), the external (or posterior) claw often with flexible main branch; double claws different in size and shape on the same leg (Hypsibius and Ramazzottius type, or modified), or very reduced in size (Calohypsibius and Microhypsibius type); buccal tube often very narrow” Hypsibioidea from Gąsiorek et al. 2018: “Eutardigrades with asymmetrical claws (2-1-2-1) and pseudolunulae at claw bases or without any cuticular structures under the basal parts. Hooked or broad-ridged apophyses for the insertion of the stylet muscles. Herbivorous or microbivorous (Guidetti et al. 2012).”

Hypsibiidae from Pilato 1969: “Senza alcuna appendice cefalica. Le due diplounghie di ciascuna zampa sono disposte asimmetricamente rispetto al piano mediano della zampa stessa e posssono essere di tipo Isohypsibius o di tipo Hypsibius. In ogni zampa le due diplounghie sono talvolta quasi uguali fra loro ma molto spesso profondamente diverse per forma e dimensioni. Lunule più spesso assenti, presenti in poche specie. L’apparato boccale è generalmente di tipo Hypsibius o Diphascon e soltanto nel genere Doryphoribius è di tipo Macrobiotus. Il bulbo faringeo è generalmente provvisto di placoidi, ne è soltanto nel genere Itaquascon.”

Translated: Without any cephalic appendages. The two double-claws of each leg are arranged asymmetrically with respect to the median plane of the leg itself and can be of the Isohypsibius or Hypsibius type. In each paw the two double-claws are sometimes almost equal to each other but very often very different in shape and size. Lunule more often absent, present in few species. The buccal apparatus is generally of the Hypsibius or Diphascon type and only in the genus Doryphoribius is of the Macrobiotus type. The pharyngeal bulb is generally provided with placoids, except in the genus Itaquascon.

Hypsibiidae from Bertolani et al. 2014: “Double claws different in shape and size on the same leg, the external (or posterior) of Hypsibius type claw with the secondary branch forming a continuous hook with its basal tract and the primary branch connected to the basal tract with a flexible part. Septulum present in the pharynx of some genera. Eggs smooth (but rarely weakly ornamented) laid within the exuvium, in some cases eggs ornamented laid free.” Hypsibiidae from Gąsiorek et al. 2018: “Eutardigrades without cephalic papillae (sensu structures present e.g. in Halobiotus Kristensen, 1982; see Møbjerg et al. 2007) and elliptical organs. Claws of the Hypsibius type, i.e. asymmetrical both with respect to the sequence of primary and secondary branches (2-1-2-1) and with respect to the size, with external and posterior claws being always clearly larger than internal and anterior claws. Accessory points symmetrical. Two types of bucco-pharyngeal apparatuses: with the buccal tube rigid over its entire length (Hypsibiinae) or with a rigid anterior buccal tube followed by a flexible posterior pharyngeal tube (all remaining subfamilies).”

Diphasconinae from Dastych 1992: “Eutardigrades with buccopharyngeal apparatus of Diphascon-type and anterior apophyses shaped as “blunt” or “semilunar” hooks (see Pilato 1987). Posteriodorsal apodeme (“drop-like” structure) present or absent, pharyngeal apophyses present. Asymmetrical claws of Hypsibiidae-type. Eggs either deposited into [shedded] cuticle and smooth or layed freely and with ornamented shells.”

Diphasconinae from Bertolani et al. 2014: “Buccal tube followed by an annulated pharyngeal tube, with a cuticular thickening between them (often drop-shaped, sometimes barely evident); pharyngeal bulb is an elongated oval, containing always 3 macroplacoids in a line (and sometimes with a microplacoid and/or septulum).”

Genus description from Plate 1888: “Diese Gattung hat grosse Aehnlichkeit mit Macrobiotus oberhäuseri, aber der kleine, runde Schlundkopf sitzt in der Mitte des Oesophagus. Das Gebiss ist zart. […] An jedem Bein 2 Doppelhaken, deren krallen am Grunde verwachsen sind.”

Translated: This genus is very similar to Macrobiotus oberhäuseri, but the small, round pharynx sits in the middle of the esophagus. The denture is delicate. On each leg there are 2 double-claws, whose branches are fused at the bottom.

Genus description from Bertolani et al. 2014: As subfamily Diphasconinae, above.

“D. pingue group” (Pilato & Binda 1999) (3-1-1, smooth without any sculpture such as granulation, pores or reticulation, without lunules and other cuticular thickenings on the legs and with claw bases without indentation: pingue, pinguiforme, claxtonae, australianum, polare, dastychi, victoriae, faialense (foutoura pilato 2007), zaniewi

“D. nobilei group” (Pilato, Binda, Bertolani, Lisi, 2005) 3-1-0 with bars I-III, legs IV (only) have wide bases with teeth/indents (may be teeth on others but not so wide), & basal spurs/spines (just extensions of base?) on at least external I-III: nobilei, serratum, nelsonae, platyungue, hydrophilum

Cheat sheet:

higginsi: 3-1-1, very small drop, wide claw base with teeth, bars I-III

pingue: 3-1-1, no teeth, no bars

nobilei: 3-1-0

nodulosum: 2-1-0, nodules larger posteriorly

patanei: 2-1-0, granules, paired gibbosities

granifer: 2-0-1, granules, no gibbosities

ramazzottii: 2-0-1, button at caudal end of placoid 1, gibbosity on each leg

Alberta:

none reported

Canada:

alpinum Murray, 1906 3-1-1 increasing 1-3, inner claws shorter & thicker, some say it’s just pingue bullatum Murray, 1905 2-0-1, gibbosities

burti Nelson, 1991 2-0-1 (with pseudoseptulum at anterior, “narrow transversely extended cuticular thickening at the junction of the lumen of the pharynx & esophagus) 1st macrop longer & constricted, no lunules or bars. Looks smooth without oil+phase, then fine granulation chilenense Plate, 1889 3-1-1, macrop equal iltisi (Schuster & Grigarick, 1965) 2-1-0 nodulosum (Ramazzotti, 1957) 2-1-0, nodules larger post. oculatum 2-0-1 pingue 3-1-1, no bars, no claw-base-teeth ramazzottii (Robotti, 1970) 2-0-1, button at caudal end of macrop. 1, gibbosity on each leg recamieri Richters, 1911 2-1-? rugosum (Bartoš, 1935) 2-1-0 (1st 2x 2nd) tenue Thulin, 1928 3-0-0 No ph apo?

North America / Nearctic:

granifer Greven, 1972 2-0-1, granules, no gibbosities higginsi Binda, 1971 3-1-1, v small drop, large claw bases with “teeth”, bars I-III nobilei (Binda, 1969) 3-1-0 patanei Binda & Pilato, 1971 2-1-0, granules, paired gibbs.

Other:

aculeatum (Maucci, 1951-1952) 2-1-1, 8 rows of 2 gibbs

australianum Pilato & Binda, 1998 3-1-1

bidropion Ito, 1995 3-1-0, two drops

birklehofi Rolf Schuster, 1999 3-1-1, bases of ext IV with
distinct teeth, bars at internal I – III

bisbullatum (Iharos, 1964) 2-0-1, large & small gibb rows

boreale Biserov, 1996 2-0-1

brevipes (Marcus, 1936) 2-0-1

claxtonae Pilato & Binda, 1998 3-1-1

dastychi Pilato & Binda, 1999 3-1-1

dolomiticum Pilato & Bertolani, 2005 3-1-0

elongatum (Mihelcic, 1959) 2-1-0, gibbs

faialense Fontoura & Pilato, 2007 3-1-1

gerdae (Mihelcic, 1951) 2-1-0, gibbs

halapiense (Iharos, 1964) 3-1-?, posterior gibbosities

humicus Bertolani, Guidetti & Rebecchi, 1995 3-1-0

hydrophilum Pilato, Binda, Bertolani & Lisi, 2005 3-1-0

iharosi Vargha, 1995 3-1-1, no bars, small spines on ant IV

langhovdense (Sudzuki, 1964) 3-1-0, macrop equal

latipes (Mihelcic, 1955) 2-1-0 (equal)

mirabilis Dastych, 1984 granulated, pseudoseptulum, bars
I-III

mitrense Pilato, Binda & Qualtieri, 1999 3-1-1 (3>1>2)

nelsonae Pilato, Binda, Bertolani & Lisi, 2005 3-1-0

nonbullatum (Mihelcic, 1951) 2-?-?, gibbs & granulation

oculatum oculatum Murray, 1906 2-0-1

oculatum alpinum (Mihelcic, 1964) 2-0-1

oculatum canadense Murray, 1910 [Hypsibius vancouverensis
Thulin, 1911] 2-0-1

ongulense (Morikawa, 1962) 3-0-1

opisthoglyptum Maucci, 1987 3-1-1, massive ph apo, macro
short (1 > 2), small eyespots, claws IV similar to
Ramazzotius claws, dorsal sculpture

pingue pingue (Marcus, 1936) 3-1-1

pingue brunsvicense Argue, 1972 3-1-1

pinguiforme Pilato & Binda, 1997/98 3-1-1

platyungue Pilato, Binda, Bertolani & Lisi, 2005 3-1-0

polare Pilato & Binda, 1999 3-1-1

puniceum (Jennings, 1976) 3-1-0, caudal granulation, pink

rugocaudatum (Rodriguez Roda, 1952) 2-1-0 or 2-0-1

sanae Dastych, Ryan & Watkins, 1990 3-0-1 equal

secchii Bertolani & Rebecchi, 1996 2-0-1

serratum Pilato, Binda, Bertolani & Lisi, 2005 3-1-0

sexbullatum Ito, 1995 6 dorsomedial gibbosities

stappersi Richters, 1911 3-1-1? 3>2>1. Eyes

trachydorsatum (Bartoš, 1937) 2-1-0? gibbosities

victoriae Pilato & Binda, 1999 3-1-1

zaniewi Kaczmarek & Michalczyk, 2004 3-1-1, 3>1=2, very narrow
bt

Below, not sure if Diphascon (Diphascon): see Adropion for details

Diphascon bicorne (Mihelcic, 1971)

Diphascon coniferens (Bartoš, 1960)

Diphascon marcuzzii (Mihelcic, 1971)

Diphascon mariae (Mihelcic, 1951)

Diphascon punctatum (Iharos, 1962)

Diphascon rivulare (Mihelcic, 1967)

Diphascon speciosum (Mihelcic, 1971)

Key modified from Wang 2009, just showing subgenus Diphascon. Has clavatum not in checklist. Missing: aculeatum, australianum, bidropion, birklehofi, bisbullatum, boreale, brevipes, bullatum, burti, claxtonae, dastychi, dolomiticum, elongatum, faialense, gerdae, granifer, halapiense, higginsi, humicus, hydrophilum, iharosi, iltisi, langhovdense, latipes, mirabilis, mitrense, nelsonae, nodulosum, nonbullatum, oculatum, ongulense, opisthoglyptum, patanei, pinguiforme, platyungue, polare, puniceum, ramazzottii, recamieri, rugocaudatum, rugosum, sanae, secchii, serratum, sexbullatum, stappersi, tenue, trachydorsatum, victoriae, zaniewi, and uncertain: bicorne, coniferens, marcuzzii, mariae, puncatatum

Key to the species of Diphascon of China

1. Cuticle sculptured or with gibbosities….……………. .….…..…..………2

Cuticle smooth………………………………………..……..…………..…3

2. Pharynx with two macroplacoids………….………….…….D. bisbullatum

Pharynx with three macroplacoids…………….……….……….D.clavatum

3. skip ahead……………………………….…………………4

4. Microplacoid and septula present………………………….………………5

Microplacoid present, septula absent……………………….……D. nobilei

5. Length of macroplacoids increaseing from first to
third…………………6

Macroplacoids about equal in length…………..…..………..D.
chilenensis

6. Body rather narrow and elongated………………..……………D. alpinum

Body wide and squat……….……………………………….…..D. pingue

Key from Fountoura & Pilato 2007 to members of the pingue group. Buccal tube length measured from anterior margin of stylet sheaths to posterior end of drop. Missing other 3-1-1: chilenense, alpinum, iharosi, opisthoglyptum, stappersi?

1 Macroplacoid row short (ptd index <50); third macroplacoid slightly longer than the first and the second
……………………………………………………………………………………………………………………………………………….. 2

– Macroplacoid row longer (ptd index >50); third macroplacoid clearly longer than the first and the second
……………………………………………………………………………………………………………………………………………….. 4

2(1)The second macroplacoid is the shortest ………………………………………………………………………….D. mitrense

– Second macroplacoid as long as the first or longer than it ……………………………………………………………….. 3

3(2) Buccal tube length is 31–35 % of the total length of the bucco-pharyngeal tube; stylet supports inserted on the buccal tube at 61–63 % of its length; drop-shaped thickening between buccal tube and pharyngeal tube forked;

claw branches particularly wide……………………………………………………………………… D. polare

– Buccal tube length is 37–40 % of the total length of the bucco-pharyngeal tube; stylet supports inserted on the buccal tube at 56–60 % of its length; drop-shaped thickening between buccal tube and pharyngeal tube not forked; claws slender ………………………………………………………………………………………………….D. pingue

4(1) Index ptd relative to the macroplacoid row length >75; third macroplacoid length almost double of that of the second ……………………………………………………………………………………………………………. D. australianum

– Index ptd relative to the macroplacoid row <70; third macroplacoid not so long………………………………… 5

5(4) Buccal tube length >40 % of the total length of the bucco-pharyngeal tube; claws long (ptd relative to the external claws III = 47–54 and to the posterior claws IV = about 61) ………………………………….D. dastychi

– Buccal tube length <40 % of the total length of the bucco-pharyngeal tube; claws not so long (ptd relative to the external claws III up to 48 and to the posterior claws IV up to 52) ………………………………………….. 6

6(5) ptd index relative to the macroplacoid row 60 or more; relative to placoid row 75 or more ……………….. 7

– ptd index relative to the macroplacoid row <60, to the placoid row <75……………………………………………. 9

7(6)Buccal tube very narrow (ptd less or equal to 5) ………………………………………………………………. D. zaniewi

– Wider buccal tube (ptd >6) …………………………………………………………………………………………………………. 8

8(7)Stylet supports inserted on the buccal tube at about 60.5–62.5 % of its length; ptd index value relative to the septulum about 10.5 ……………………………………………………………………………………………… D. victoriae

– Stylet supports inserted on the buccal tube at about 57–58.5 % of its length; ptd index value relative to the septulum about 12–14………………………………………………………………………………………………D. pinguiforme

9(6)The buccal tube length is about 32–35 % of the total length of the bucco-pharyngeal tube; ptd index value relative to the septulum = 9.5–10.5 ……………………………………………………………………………….D. claxtonae

– The buccal tube length is about 37 % of the total length of the bucco-pharyngeal tube; ptd index value relative to the septulum about 11 ………………………………………………………………………………………. D. faialense

Citations
Left image from Bertolani R, Guidetti R, Rebecchi L. 1994. Ulteriore contributo alla conoscenza dei tardigradi delle Marche e dell’Umbria. Atti della Società toscana di Scienze Naturali Memorie, Serie B. 101: 21-34. Right image from Plate LH. 1888. Beiträge zur Naturgeschichte der Tardigraden. Zoologische Jahrbücher, Abteilung für Anatomie und Ontogenie der Tiere. 3: 487-550. Marley NJ, McInnes SJ, Sands CJ. 2011. Phylum Tardigrada: A re-evaluation of the Parachela. Zootaxa. 2819: 51-64. 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. Dastych H. 1992. Paradiphascon manningi gen. n. sp. n., a new water-bear from South Africa, with the erecting of a new subfamily Diphasconinae (Tardigrada). Mitteilungen aus den Hamburgischen Zoologischen Museum und Institut. 89: 125-139. Gąsiorek P, Stec D, Morek W, Michalczyk Ł. An integrative redescription of Hypsibius dujardini (Doyère, 1840), the nominal taxon for Hypsibioidea (Tardigrada: Eutardigrada). Zootaxa. 4415 (1): 45-75. Pilato G. 1969. Schema per una nuova sistemazione delle famiglie e dei generi degli Eutardigrada. Bollettino delle Sedute della Accademia Gioenia di Scienze Naturali in Catania, Series IV. 10 (277): 181-193.

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