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Keys and Bibliography to the Collembola

Family Isotomidae Schaeffer, 1896

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Family Isotomidae Schaeffer, 1896

Sub-Family † Anurophorinae Börner, 1901

† This name is reverted to here pending the decision of the International Commission on Zoological Nomenclature regarding the retention on the official list of the genus Anurophorus Nicolet.

Key to the Genera of the Anurophorinae
1. Anal spines present on Abds. V–VI 2
Anal spines absent 4page 18
2. Anal spines on Abd. V, 15–30, arranged as a crown; dens and mucro fused Proctostephanus Börner, 1902 (142)
Anal spines on Abd. VI; furcula present or absent; ocelli, eight to each side 3
3. Anal spines, two, small; unguiculus absent; furcula absent Uzelia Absolon, 1901 (13)
=Pentapleotoma Börner, 1903 (144)
Protanurophorus Womersley, 1925 (1150)
Anal spines, four, large; unguiculus present; furcula present or absent Tetracanthella Schött, 1891 (951)
=Lubbockia Haller, 1880 (524)
Deuterolubbockia Dalla Torre, 1895 (280)
4. Furcula present, sometimes partially reduced 5
Furcula absent or sometimes represented by a papilla 12
5. Abdominal segments distinctly separated and visible from above 6
Abds. IV–VI fused or VI more or less concealed beneath Abd. V 11
6. Ocelli present, but reduced in number 7
Ocelli absent; furcula reaching to middle of Abd. III only; mucro and dens indistinctly separated; claw with tunica Womersleyella Salmon, 1944 (917)
7. Body extremely elongate or posteriorly flexed downwards 8
Body not so; more normal; ocelli, six to each side 9
8. All Abdominal segments sub-equal; ocelli, one, two, or five to each side; unguiculus simple Folsomides Stach, 1922 (1004)
Abds. V and VI bent downwards; ocelli, five or eight to each side Subisotoma Stach, 1947 (1027)
9. Unguiculus normal, simple 10
Unguiculus three winged; dens with 4–5 transverse posterior folds Jacksoniella Denis, 1931 (368)
10. Furcula well developed; integument very granular Astephanus Denis, 1927 (360)
Furcula reduced; mucro hook-like; integument reticulate Coloburella Latzel, 1917 (665)
11. Abd. VI concealed beneath Abd. V Cryptopygus Willem, 1902 (1138)
Abds. IV—VI fused; anus ventral; ocelli absent; body extremely elongate; furcula short, not reaching to Abd. III Isotomodes Axelson, 1907 (60)
12. Furcula represented by a papilla 13
Furcula absent 14
13. Cuticle with honeycombed appearance; clavate tenent hairs absent from foot Paranurophorus Denis, 1929 (363)
Cuticle very granulate; clavate tenent hairs present on foot; papilla of furcula with two short ridges Boernerella Denis, 1925 (351)
14. Anal papillae present; body elongate; ocelli reduced Pseudanurophorus Stach, 1922 (1004)
Anal papillae absent; body normal; ocelli normal Anurophorus Nicolet, 1841 (797)
=Adicranus Bourlet, 1843 (160)
Bourletia MacGillivray, 1893 (724)
Sub-Family Proisotominae Stach, 1947
Key to the Genera of the Proisotominae
1. Abds. V–VI or IV–VI fused, forming a single mass 2
All abdominal segments distinctly separated or segments V and VI partly fused, with a trace of dorsal suture still visible 7page 19
2. Abds. V–VI fused; body setae arranged as transverse bands around posterior margins of thoracic and first four abdominal segments Parafolsomia Salmon, 1949 (925)
Abds. IV–VI fused; postantennal organ present, elliptical 3
3. Mucro dentate 4
Mucro falciform 6
4. With eight ocelli to each side * Bagnallella nov.
With fewer than eight ocelli to each side 5
5. With 2–5 ocelli to each side Folsomidiella Bagnall, 1949 (88)
Ocelli absent; postantennal organ long, elliptical, and usually narrow * Folsomia Willem, 1902 (1141)
=* Litsteria Bagnall, 1949 (88)
6. Ocelli present, reduced in number; postantennal organ present; Ant IV without sense clubs Arlea Womersley, 1939 (1181)
Ocelli absent; postantennal organ absent; Ant. IV with 5–6 large sense clubs and two broad sense lobes Folsomia Denis, 1931 (368)
=Denisia Folsom, 1932 (466)
7. Body form normal, without bulging segments or deep intersegmental constrictions 8
Body with the segments bulging and deep intersegmental constrictions; unguiculus three-winged; ocelli, eight to each side. Guthriella Börner, 1906 (147)
8. Dens normal without terminal expansions 9
Dens with, a large terminal bladder-like lateral lobe on outer edge; ocelli, eight to each side; Abds. V–VI fused with dorsal suture Appendisotoma Stach, 1947 (1027)
9. Bothriotrichia present on abdominal segments 10
Bothriotrichia absent 11
10. With one pair dorsal bothriotrichia on Abd. IV; hind femur normal; mucro with apical, sub-apical, and proximal teeth and four lamellae Hydroisotoma Stach, 1947 (1027)
With two pairs dorsal bothriotrichia on Abds. V–VT; hind femur with large spine-like process; mucro with three teeth in which one is apical and the others form a pair side by side near base Archisotoma Linnaniemi, 1912 (690)
11. Dentes shorter than manubrium, usually granulate, coarsely tuberculate, crenulate, or notched; mucro with 2–4 teeth and with or without lamellae; Abds. V–VI separate or partly fused; ocelli, eight to each side Proisotoma Börner, 1901 (140)
Dentes longer than manubrium, usually smooth, but heavily clothed with setae; mucro long, bidentate, with broad lamellae; Abds. V–VI separated Ballistrura Börner, 1906 (147)
Sub-Family Isotominae Schaeffer, 1896

* Bagnall has proposed a genus Litsteria for those species previously included in Folsomia but in which the eyes are reduced to two, one, or none to each side. Folsomia, however, has for its genotype F. fimetaria, which has no ocelli. Bagnall's name Litsteria fails therefore, as a synonym. He has also proposed the genus Folsomidiella for those Folsomia species with five ocelli to each side. This is in order, but I propose that the definition of Folsomidiella be enlarged to include those species with 1–5 ocelli to each side and that a new genus Bagnallella be erected to include those species with eight ocelli to each side previously included in the genus Folsomia. The genotype of Bagnallella will be B. (F.) sedecimoculata Salmon (944).

* Stach (1055) criticises this genus and suggests that the species P. fuscus and P. parvus belong to Vertagopus and P. dissimilis to Tomocerura, basing this opinion on the structures of the feet and furcula. He apparently ignores the extraordinary integumentary feature of the papillate setae. I cannot accept his view, as I consider the papillate setae a most striking character of generic importance. Recently (953) I have described three more species belonging to the genus from the Antarctic.

Key to the Genera of the Isotominae
1. Fine wavy sensory ciliated hairs (lasiotrichia) on abdominal segments 2
Without lasiotrichia 8
2. Dentes with either simple or serrated spines 3
Dentes without spines 5page 20
3. Dental spines serrated 4
Dental spines simple, but each spine arising from a papilla Proisotomurus Womersley, 1934 (1169)
4. Ant. III and Ant IV annulated; tibiotarsi broad and flattened Tibiolatra Salmon, 1941 (910)
Antennae not annulated; tibiotarsi normal Acanthomurus Womersley, 1934 (1169)
5. Body of peculiar form; Ant III and Ant IV annulated; ocelli reduced, six to each side; mucro with three teeth Architomocerura Denis, 1931 (369)
Body normal in form; ocelli, eight to each side; antennae not annulated 6
6. Sense organ Ant. III normal, with not more than 2–3 sense rods 7
Sense organ Ant III with two blunt sense rods and 15–20 short truncated sensory hairs Axelsonia Börner, 1906 (147)
=Moniezina Denis, 1922 (343)
7. Mucro quadridentate Isotomurus Börner, 1903 (144)
Mucro falciform Falcisotomina Stach, 1947 (1027)
8. Claw with basal tunica 9
Claw without basal tunica 10
9. Dens with long terminal seta over-reaching mucro; mucro tridentate with lamellae; clavate tenent hairs absent Agrenia Börner, 1906 (147)
Dens without terminal seta; mucro quadridentate without lamellae; broadly spathulate tenent hairs present Pteronychella Börner, 1909 (150)
10. Flexed setae on thoracic and abdominal segments; postantennal organ present or absent 11
Without flexed setae; postantennal organ present or absent 12
11. Mucro bidentate; Abd. IV not much longer than Abd. III; foot without clavate tenent hairs Corynothryx Tullberg, 1876 (1075)
Mucro falciform; Abd. IV three times longer than Abd. III; clavate tenent hairs present on foot Isotobrya Womersley, 1934 (1169)
12. Setae of the body and appendages each arising from a distinct wart or papilla * Papillomurus Salmon, 1941 (910)
Setae not arising from warts or papillae 13
13. Body of normal form without swellings or processes 14
Body with abnormal spine-like or papillate processes or clusters of setae 32
14. Manubrium with spines 15
Manubrium without spines 16
15. Manubrium and dens both with spines; mucro tridentate; setae simple, ciliated, and serrated; postantennal organ present elongate, elliptical Sorensia Salmon, 1949 (925)
Manubrium only with a terminal group of seven spines on posterior aspect; mucro tridentate Acanthisotoma Bonet, 1942 (123)
16. Dens spined, the spines all simple 17
Dens without spines 21
17. Spines of dens each arising from a wart or papilla 18
Spines of dens without warts or papillae 19page 21
18. Spines of dens all slender and up to four rows; clavate tenent hairs present Procerura Salmon, 1941 (910)
Spines of dens of two kinds; two rows of slender spines and up to three rows of short stout spines; clavate tenent hairs absent Spinocerura Salmon, 1941 (910)
19. Mucro dentate with four teeth 20
Mucro falciform; clothing of long pubescent setae Millsia Womersley, 1942 (1184)
20. Clothing of simple setae; postantennal organ present Setocerura Salmon, 1949 (925)
Clothing of ciliated setae; postantennal organ absent Tomocerura Wahlgren, 1900 (1105)
21. Abd. IV bearing excessively long setae Alloschaefferia Börner, 1903 (144)
Abd. IV with normal setae 22
22. Abd. IV equal to or shorter than Abd. III 23
Abd. IV longer than Abd. III 27
23. Tenent hairs present on each foot 24
Tenent hairs absent 25
24. Abds. V and VI fused; furcula reaching ventral tube; mucro with three teeth Pseudisotoma Handschin, 1924 (530)
Abds. V and VI not fused; furcula reaching only posterior margin of Abd. II; mucro with four teeth Vertagopus Börner, 1906 (147)
25. Furcula reaching forward to ventral tube; Abds. V and VI not fused 26
Furcula reaching only posterior margin of Abd. II; some setae strongly serrated; Abds. V–VI fused Isotomedia Salmon, 1944 (917)
26. Setae of the body simple Isotoma Bourlet, 1839 (159)
=Podura Müller, 1776 (789)
Desoria Nicolet, Agassiz, 1841 (797) (24)
Apoeona Gistl, 1848 (510)
Setae of the body serrated Euisotoma Börner, 1901 (140)
27. Abd. V. and Abd. VI fused 28
Abd V and VI not fused 29
28. Ocelli, eight to each side; postantennal organ elongate elliptical, with a constriction at its middle Isotomina Börner, 1903 (144)
Ocelli reduced, six or fewer to each side; postantennal organ present, elliptical and sometimes constricted at middle Proisotomina Salmon, 1948 (921)
29. Ocelli, eight to each side; postantennal organ with thickened, flap-like, divided margins; mucro tridentate; tenent hairs absent Heteroisotoma Stach, 1947 (1027)
Ocelli reduced; postantennal organ without thickened margins or absent 30
30. Ocelli, six or fewer to each side; postantennal organ present Parisotoma Bagnall, 1940 (84)
Ocelli absent 31
31. Postantennal organ present Isotominella Delamare-Deboutteville, 1948 (332)
Postantennal organ absent Isotomiella Bagnall, 1940 (84)
32. Body of male with terminal abdominal spines or horn-like structures on head 33
Ant. II in male with cluster of short, thick, ciliated setae; Abd. III, at centre, with cluster of moderately long, curved, ciliated setae; tenent hairs absent; mucro bidentate; body with numerous stout, blunt, ciliated bristles Australotomurus Stach, 1947 (1027)page 22
33. Abd. V, in the male, dorsally with 4–6 stout spines; clavate tenent hairs absent; Abds. V and VI not fused; mucro with two or four teeth Spinisotoma Stach, 1926 (1009)
Males with long curved horns on top of head; antennae thickened; clavate tenent hairs present; Abds. V–VI fused; mucro with three teeth Rhodanella Salmon, 1945 (918)
=Rhodesia Womersley, 1934 (1169)

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