http://www.collembola.org/key/onycinae.htm - Last updated on 2017.02.28 by Frans Janssens
Checklist of the Collembola: Key to the genera of Onychiurinae

This key is still under construction. Note that missing figures will be provided as soon as possible. Currently, the key is in the feasibility study phase to find out how to integrate in the checklist in a modular way a key that has been generated with DELTA.

Romuald J. Pomorski, Zoological Institute, Wroclaw University, Pl-50-335 Wroclaw, Poland
Kenneth A. Christiansen, Department of Biology, Grinnell College, Grinnell, IA 50112-0806, USA
Yulija B. Sveenkova, State Nature Reserve "Privolzhskaya Lesostep" Okruzhnaya 12a, 440008 Penza, Russia
David Steinmann, Boulder, Colorado 80302, USA
Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium

Introduction

In this subfamily are included all Onychiuridae with the furcula rudimentary or absent, no dark pigment, and four or more papillae in an apical organ on the third antennal segment (Fig. Intro.A).

Fig.Intro. Characteristics useful in identification of Onychiurinae
A. Location of postantennal organ and third antennal segment sense organ
   c - sense club, r - sense rod, p - paddle shaped sensilla
B. Typical distribution of ventral pseudocelli; left side, species with more numerous pseudocelli
C. Dividing line between dorsal and ventral pseudocelli
D. Forms of parapseudocelli
Characters found most useful in classification are:

  1. Apical organ of the third antennal segment: number of papillae and guard setae, form of sense clubs. See Fig. Intro.A for the location of this organ.
  2. Post antennal organ (P.A.O.): shape, arrangement, and number of tubercles. See Fig. Intro.A. Both the organs are frequently difficult to make out; we have found them easiest to study in well-flattened specimens, or in temporary mounts in which the specimen can be rolled to the proper orientation.
  3. Pseudocelli: number and arrangement on the head and first 8 trunk segments. There is some confusion in the literature as to the dorsal or ventral position of the more lateral pseudocelli; Fig. Intro.C shows the dividing line which has been used to separate dorsal and ventral pseudocelli. The pseudocellus indicated by the arrow has been assigned previously to either the fourth or fifth abdominal segments; it is here placed arbitrarily on the fourth. The ventral pseudocelli are often obscure and hard to locate; Fig. Intro.B&C shows in diagrammatic fashion 2 typical patterns of distribution. As pseudocelli are recognised only those circular or oval areas with smooth or ridged inner surfaces; similar areas with finely granulate inner surfaces are considered to be foveae.
  4. Parapseudocelli (Fig. Intro.D). These organs resemble pseudocelli but they are long and slit like or elongate elliptical. They always lack the chitinized border common in pseudocelli. They are generally limited to ventral surfaces, legs and anal lobes.
  5. Chaetotaxy: this appears to be stable in some species and quite variable in others; the variation may be partly geographic and may include sexual dimorphism. General form and differentiation of setae and their arrangement on the fifth abdominal tergite, second abdominal sternite, and antennae have been found useful in certain species. This character is worth much more attention.
  6. Structure of the unguiculus, and occasionally of the unguis and tenent hairs.
  7. Presence or absence, and structure, of the anal spines.
  8. Integumentary granulation: apply to the dorsal surface of the head and the tergites, and generally neglect the finer areas of granulation on the intersegmental membranes and in the foveae.
  9. The male ventral organ: this is made up of 1 or more groups of setae, slightly to highly modified, on the venter of 1 or more of abdominal segments 2, 3, and 4. Not all species have this structure and even when present it is developed only in mature males, but in certain groups it provides the best feature for species recognition. The organ often continues to differentiate in additional molts after sexual maturity.
  10. The presence or absence and form of the vestiges of the furcula.
  11. Microsensilla which occur on the lateral margins of the thorax are of taxonomic importance.

Most of these characters are best seen in dorsoventrally flattened specimens.

Note: The key does not include the genus Pseudonychiurus Bagnall, 1948. The settlement of taxonomic position of this genus at this moment is impossible. Typical species - Aphorura dentata Folsom, 1902 should be redescribed.

Rationale

Check the rationale for taxa used and not used as well as subtaxonomic classification for some taxa.

Key

Note that no distinction between subtaxa and taxa is made in the key.

   
1(0).   Posterior cephalic pseudocelli absent (fig.1a).............. 2
        Posterior cephalic pseudocelli present (fig.1b)............ 11
 

Fig.1.
 
2(1).   Third antennal segment sense organ with 4-5 papilla, no
          papilla-like prominence................................... 3
        Third antennal segment sense organ with 5 papilla and
          additional papilla-like prominence (fig.2)............... 9
 

Fig.2.
 
3(2).   Third abdominal tergum with submedial pseudocelli........... 4
        Third abdominal tergum without submedial pseudocelli........ 8
 
4(3).   Furca reduced to finely granulated area with setulae
          posteriorly tenaculum absent.............................. 5
        Furca reduced to two knobs with 3 + 3 or 4 + 4 setulae...... 7
 
5(4).   Labium with 4 papillae, lateral 'E' papilla absent (fig.3b);
          third antennal segment sense organ with 4 guard setae
          (fig.3a)..................................... Hymenaphorura
        Labium with 5 papillae, lateral 'E' papilla present (fig.3d);
          third antennal segment sense organ with 5 guard setae
          (fig.3c)................................................. 6
 

Fig.3.
 
6(5).   Body with very distinct parapseudocelli; granular areas of
          fourth abdominal tergum fused together midline into one
          plate (fig.4a); labium type '0' - with all 5 papillae
          apically pointed................................ Sacaphorura
        Body without parapseudocelli; granular areas on fourth
          abdominal tergum separated by 2 medial parallel rows of
          smaller granules (fig.4b); labium type 'A' thickened and
          apically blunt.................................. Vexaphorura
 

Fig.4.
 
7(4).   Anterior cephalic pseudocelli located inside antennal area
          (fig.5a); body fusiform (fig.6a).............. Kalaphorura
        Anterior cephalic pseudocelli located outside of antennal area
          (fig.5b); body oval-elliptical (fig.6b)..... Psyllaphorura
 

Fig.5.
 

Fig.6.
 
8(3).   Chaetotaxy on terga consists of one kind of setae: all setae
          apically pointed; furca reduced to a small area of fine
          granulation with 4 setulae arranged in one row or an arch
          located in a middle part of sternum iv (fig.7b); vesicles
          in postantennal organ of three kinds - simple, bilobed or
          multilobed - located perpendicularly or obliquely to the
          long axis of the organ........................ Heteraphorura
        Chaetotaxy on terga consists of two kinds of setae: blunt
          rod-like mesosetae and pointed microsetae; furca reduced to
          a small depression with 2 small, posterior setae, in contact
          with the border between abdominal sterna iii and iv
          (fig.7a); vesicles in postantennal organ compound..........
           ............................................. Paronychiurus
 

Fig.7.
 
9(2).   Furca reduced to a small concavity without granulation;
          pseudocelli absent; tibiotarsi with 11 distal setae...... 10
        Furca reduced to a small depression without granulation with 2
          setulae posteriorly; pseudocelli present; tibiotarsi with 9
          distal setae........................................ Arneria
 
10(9).  Body with parapseudocelli always located outside of areas of
          coarser granulation; macrosetae rod-like and apically blunt;
          vestigial furcal area with 4 setulae posteriorly arranged in
          one row......................................... Dinochiurus
        Body without parapseudocelli; macrosetae apically pointed;
          vestigial furcal area with 2 setulae posteriorly. Reducturus
 
11(1).  Body with lateral pseudocelli (fig.1b)..................... 12
        Body without lateral pseudocelli (fig.1a)...... Probolaphorura
 
12(11). Postantennal organ fully developed (fig.8b-e).............. 13
        Postantennal organ reduced to long furrow, without vesicles
          (fig.8a)...................................... Cribrochiurus
 

Fig.8.
 
13(12). Postantennal organ with 3-5 lobes of one vesicle (fig.8b).. 14
        Postantennal organ with 8 or more vesicles (fig.8c-e)...... 17
 
14(13). Tibiotarsi with clavate setae in distal whorl (fig.9)........
           ........................................... Chribellphorura
        Tibiotarsi with typical acuminate setae in distal whorl.... 15
 

Fig.9.
 
15(14). Anal spines absent............................... Archaphorura
        Anal spines present........................................ 16
 
16(15). Furca reduced to cuticular furrow or finely granulated area
          with 1 + 1 setulae posteriorly (fig.10b, c).... Micraphorura
        Furca reduced to cuticular furrow or finely granulated area
          with 2 + 2 setulae posteriorly (fig.10a)....... Oligaphorura
 

Fig.10.
 
17(13). Seta d0 on the head absent (fig.11a)........................ 18
        Seta d0 on the head present (fig.11b)....................... 26
 

Fig.11.
 
18(17). Vesicles in postantennal organ compound (fig.8d)........... 19
        Vesicles in postantennal organ simple (fig.8c)............. 20
 
19(18). Sense organ of third antennal segment with more then three
          guard setae...................................... Detriturus
        Sense organ of third antennal segment with only three guard
          setae..................................... Sensillonychiurus
 
20(18). Anal spines absent......................................... 21
        Anal spines present........................................ 23
 
21(20). Pseudocelli elevated (fig.12)................. Similonychiurus
        Pseudocelli not elevated................................... 22
 

Fig.12.
 
22(21). Sense clubs of sense organ of third antennal segment
          granulate..................................... Jacekaphorura
        Sense clubs of sense organ of third antennal segment unique,
          with triradiate or quadriradiate simple pointed lobes.......
           .............................................. Spelaphorura
 
23(20). Furca reduced to finely granulated area........... Megaphorura
        Furca vestigial............................................ 24
 
24(23). Furca reduced to cuticular pocket with 2 + 2 or 1 + 1 setulae
          (fig.13b)................................................ 25
        Furca reduced to two knobs with rudiment of mucro (fig.13a)...
           .............................................. Supraphorura
 

Fig.13.
 
25(24). Microsensillum of fourth antennal segment located at the level
          of second row of setae......................... Protaphorura 2
        Microsensillum of fourth antennal segment located on the basal
          part of apical third.......................... Yoshiiphorura 1
 
26(17). Furca reduced to finely granulated area with 2 + 2 setulae in
          one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or
          to cuticular pocket with 2 + 2 setulae (fig.15b)......... 27
        Furca reduced to finely granulated area with 2 + 2 setulae in
          two rows posteriorly (fig.15a)........................... 36
 

Fig.14.
 

Fig.15.
 
27(26). Claw as long as antenna; third antennal segment sense organ
          with two rows of guard papillae............. Ongulonychiurus
        Claw as long as first proximal antennal segment; third
          antennal segment sense organ with one row of guard papillae.
           ........................................................ 28
 
28(27). Distal whorl of setae on tibiotarsi with 11 pointed setae
          (fig.16a)................................................ 29
        Distal whorl of setae on tibiotarsi with 9 or 7 pointed setae
          (fig.16b, c)............................................. 34
 

Fig.16.
 
29(28). Furca reduced to cuticular pocket with 2 + 2 setulae
          (fig.14b)...................................... Bionychiurus
        Furca reduced to finely granulated area with 1 + 1 setulae
          posteriorly (fig.14d), or without trace of furca......... 30
 
30(29). Body feebly plurichaetotic; microsensillum of fourth antennal
          segment near its base.................................... 31
        Body strongly plurichaetotic; microsensillum of fourth
          antennal segment near its apex.................... Absolonia
 
31(30). Head with 2 + 2 posterior pseudocelli.......... Vibronychiurus
        Head with at least 3 + 3 posterior pseudocelli, if only 3 + 3
          pseudocelli always arranged in a triangle................ 32
 
32(31). Anal spines absent......................................... 33
        Anal spines present............................ Deharvengiurus
 
33(32). Terga with multiplication of pseudocelli........ Argonychiurus
        Terga with typical 3-4 pseudocelli.............. Onychiuroides
 
34(28). Anal spines absent......................................... 35
        Anal spines present................................ Onychiurus
 
35(34). Dorsal sense organ of third antennal segment with 5 papilla
          and bent sensory clubs (fig.17a); furca reduced to finely
          granulated area with 2 + 2 setulae posteriorly arranged in
          one row (fig.14c)............................ Deuteraphorura
        Dorsal sense organ of third antennal segment with straight
          sensory clubs and usually with 4 papilla (fig.17b); furca
          reduced to finely granulated area with 1 + 1 setulae
          posteriorly (fig.14d)........................ Orthonychiurus
 

Fig.17.
 
36(26). Distal whorl of setae on tibiotarsi with 7 setae (fig.16c). 37
        Distal whorl of setae on tibiotarsi with more than 7 setae. 38
 
37(36). Anal spines absent................................ Agraphorura
        Anal spines present.......................... Tantulonychiurus
 
38(36). Vesicles in postantennal organ compound.................... 39
        Vesicles in postantennal organ simple......... Thalassaphorura
 
39(38). Anal spines seta-like located without papillae. Micronychiurus
        Anal spines strong on distinct papillae......... Allonychiurus


Endnotes

1. Most of the diagnostic characters of this genus are removed, because true Protaphorura species have similar structure of furcal fold, with protergal pseudocelli and multiplication of setae on abdominal tergum VI (a last character is connected with large size of species - ca. 3 mm). The localization of the microsensillum is left as diagnostic, because this character is not found in true Protaphorura. Yoshiiphorura is a very good example of erection of a paraphiletic genus. The synonymisation of the genus in this key would be illegal, so it will be done in a printed publication.

2. The genus Heteronychiurus is synonymised it with Protaphorura (Pomorski, Leithner & Brucken, 2003:311).


Differential diagnoses

Absolonia
Body with lateral pseudocelli (fig.1b). Body strongly plurichaetotic. Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d), or without trace of furca. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Microsensillum of fourth antennal segment near its apex. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Agraphorura
Anal spines absent. Body with lateral pseudocelli (fig.1b). Distal whorl of setae on tibiotarsi with 7 setae (fig.16c). Furca reduced to finely granulated area with 2 + 2 setulae in two rows posteriorly (fig.15a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b).

Allonychiurus
Anal spines strong on distinct papillae. Body with lateral pseudocelli (fig.1b). Distal whorl of setae on tibiotarsi with more than 7 setae. Furca reduced to finely granulated area with 2 + 2 setulae in two rows posteriorly (fig.15a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Vesicles in postantennal organ compound.

Archaphorura
Anal spines absent. Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 3–5 lobes of one vesicle (fig.8b). Posterior cephalic pseudocelli present (fig.1b). Tibiotarsi with typical acuminate setae in distal whorl.

Argonychiurus
Anal spines absent. Body with lateral pseudocelli (fig.1b). Body feebly plurichaetotic. Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d), or without trace of furca. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Head with at least 3 + 3 posterior pseudocelli, if only 3 + 3 pseudocelli always arranged in a triangle. Microsensillum of fourth antennal segment near its base. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Terga with multiplication of pseudocelli. Third antennal segment sense organ with one row of guard papillae.

Arneria
Furca reduced to a small depression without granulation with 2 setulae posteriorly. Posterior cephalic pseudocelli absent (fig.1a). Pseudocelli present. Third antennal segment sense organ with 5 papilla and additional papilla-like prominence (fig.2). Tibiotarsi with 9 distal setae.

Bionychiurus
Body with lateral pseudocelli (fig.1b). Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to cuticular pocket with 2 + 2 setulae (fig.14b). Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Chribellphorura
Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with fig.8–5 lobes of one vesicle (fig.8b). Posterior cephalic pseudocelli present (fig.1b). Tibiotarsi with clavate setae in distal whorl (fig.9).

Cribrochiurus
Body with lateral pseudocelli (fig.1b). Postantennal organ reduced to long furrow, without vesicles (fig.8a). Posterior cephalic pseudocelli present (fig.1b).

Deharvengiurus
Anal spines present. Body with lateral pseudocelli (fig.1b). Body feebly plurichaetotic. Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d), or without trace of furca. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Head with at least 3 + 3 posterior pseudocelli, if only 3 + 3 pseudocelli always arranged in a triangle. Microsensillum of fourth antennal segment near its base. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Detriturus
Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Sense organ of third antennal segment with more then three guard setae. Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ compound (fig.8d).

Deuteraphorura
Anal spines absent. Body with lateral pseudocelli (fig.1b). Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 9 or 7 pointed setae (fig.16b, c). Dorsal sense organ of third antennal segment with 5 papilla and bent sensory clubs (fig.17a). Furca reduced to finely granulated area with 2 + 2 setulae posteriorly arranged in one row (fig.14c). Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Dinochiurus
Body with parapseudocelli always located outside of areas of coarser granulation. Furca reduced to a small concavity without granulation. Macrosetae rod-like and apically blunt. Posterior cephalic pseudocelli absent (fig.1a). Pseudocelli absent. Third antennal segment sense organ with 5 papilla and additional papilla-like prominence (fig.2). Tibiotarsi with 11 distal setae. Vestigial furcal area with 4 setulae posteriorly arranged in one row.

Heteraphorura
Chaetotaxy on terga consists of one kind of setae: all setae apically pointed. Furca reduced to a small area of fine granulation with 4 setulae arranged in one row or an arch located in a middle part of sternum iv (fig.7b). Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum without submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence. Vesicles in postantennal organ of three kinds - simple, bilobed or multilobed - located perpendicularly or obliquely to the long axis of the organ.

Hymenaphorura
Furca reduced to finely granulated area with setulae posteriorly tenaculum absent. Labium with 4 papillae, lateral ’E’ papilla absent (fig.3b). Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum with submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence. Third antennal segment sense organ with 4 guard setae (fig.3a).

Jacekaphorura
Anal spines absent. Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Pseudocelli not elevated. Sense clubs of sense organ of third antennal segment granulate. Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Kalaphorura
Anterior cephalic pseudocelli located inside antennal area (fig.5a). Body fusiform (fig.6a). Furca reduced to two knobs with 3 + 3 or 4 + 4 setulae. Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum with submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence.

Megaphorura
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca reduced to finely granulated area. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Micraphorura
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca reduced to cuticular furrow or finely granulated area with 1 + fig.1 setulae posteriorly (fig.10b, c). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 3–5 lobes of one vesicle (fig.8b). Posterior cephalic pseudocelli present (fig.1b). Tibiotarsi with typical acuminate setae in distal whorl.

Micronychiurus
Anal spines seta-like located without papillae. Body with lateral pseudocelli (fig.1b). Distal whorl of setae on tibiotarsi with more than 7 setae. Furca reduced to finely granulated area with 2 + 2 setulae in two rows posteriorly (fig.15a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Vesicles in postantennal organ compound.

Oligaphorura
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca reduced to cuticular furrow or finely granulated area with 2 + fig. setulae posteriorly (fig.10a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 3–5 lobes of one vesicle (fig.8b). Posterior cephalic pseudocelli present (fig.1b). Tibiotarsi with typical acuminate setae in distal whorl.

Ongulonychiurus
Body with lateral pseudocelli (fig.1b). Claw as long as antenna. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with two rows of guard papillae.

Onychiuroides
Anal spines absent. Body with lateral pseudocelli (fig.1b). Body feebly plurichaetotic. Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d), or without trace of furca. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Head with at least 3 + 3 posterior pseudocelli, if only 3 + 3 pseudocelli always arranged in a triangle. Microsensillum of fourth antennal segment near its base. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Terga with typical 3–4 pseudocelli. Third antennal segment sense organ with one row of guard papillae.

Onychiurus
Anal spines present. Body with lateral pseudocelli (fig.1b). Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 9 or 7 pointed setae (fig.16b, c). Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Orthonychiurus
Anal spines absent. Body with lateral pseudocelli (fig.1b). Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 9 or 7 pointed setae (fig.16b, c). Dorsal sense organ of third antennal segment with straight sensory clubs and usually with 4 papilla (fig.17b). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d). Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Paronychiurus
Chaetotaxy on terga consists of two kinds of setae: blunt rod-like mesosetae and pointed microsetae. Furca reduced to a small depression with 2 small, posterior setae, in contact with the border between abdominal sterna iii and iv (fig.7a). Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum without submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence. Vesicles in postantennal organ compound.

Probolaphorura
Body without lateral pseudocelli (fig.1a). Posterior cephalic pseudocelli present (fig.1b).

Protaphorura 2
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca vestigial. Furca reduced to cuticular pocket with fig. + 2 or 1 + 1 setulae (fig.13b). Microsensillum of fourth antennal segment located at the level of second row of setae. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Psyllaphorura
Anterior cephalic pseudocelli located outside of antennal area (fig.5b). Body oval-elliptical (fig.6b). Furca reduced to two knobs with 3 + 3 or 4 + 4 setulae. Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum with submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence.

Reducturus
Body without parapseudocelli. Furca reduced to a small concavity without granulation. Macrosetae apically pointed. Posterior cephalic pseudocelli absent (fig.1a). Pseudocelli absent. Third antennal segment sense organ with 5 papilla and additional papilla-like prominence (fig.2). Tibiotarsi with 11 distal setae. Vestigial furcal area with 2 setulae posteriorly.

Sacaphorura
Body with very distinct parapseudocelli. Furca reduced to finely granulated area with setulae posteriorly tenaculum absent. Granular areas of fourth abdominal tergum fused together midline into one plate (fig.4a). Labium type ’0’ - with all 5 papillae apically pointed. Labium with 5 papillae, lateral ’E’ papilla present (fig.3d). Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum with submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence. Third antennal segment sense organ with 5 guard setae (fig.3c).

Sensillonychiurus
Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Sense organ of third antennal segment with only three guard setae. Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ compound (fig.8d).

Similonychiurus
Anal spines absent. Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Pseudocelli elevated (fig.12). Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Spelaphorura
Anal spines absent. Body with lateral pseudocelli (fig.1b). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Pseudocelli not elevated. Sense clubs of sense organ of third antennal segment unique, with triradiate or quadriradiate simple pointed lobes. Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Supraphorura
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca vestigial. Furca reduced to two knobs with rudiment of mucro (fig.13a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).

Tantulonychiurus
Anal spines present. Body with lateral pseudocelli (fig.1b). Distal whorl of setae on tibiotarsi with 7 setae (fig.16c). Furca reduced to finely granulated area with 2 + 2 setulae in two rows posteriorly (fig.15a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b).

Thalassaphorura
Body with lateral pseudocelli (fig.1b). Distal whorl of setae on tibiotarsi with more than 7 setae. Furca reduced to finely granulated area with 2 + 2 setulae in two rows posteriorly (fig.15a). Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Vesicles in postantennal organ simple.

Vexaphorura
Body without parapseudocelli. Furca reduced to finely granulated area with setulae posteriorly tenaculum absent. Granular areas on fourth abdominal tergum separated by 2 medial parallel rows of smaller granules (fig.4b). Labium type ’A’ thickened and apically blunt. Labium with 5 papillae, lateral ’E’ papilla present (fig.3d). Posterior cephalic pseudocelli absent (fig.1a). Third abdominal tergum with submedial pseudocelli. Third antennal segment sense organ with 4–5 papilla, no papilla-like prominence. Third antennal segment sense organ with 5 guard setae (fig.3c).

Vibronychiurus
Body with lateral pseudocelli (fig.1b). Body feebly plurichaetotic. Claw as long as first proximal antennal segment. Distal whorl of setae on tibiotarsi with 11 pointed setae (fig.16a). Furca reduced to finely granulated area with 1 + 1 setulae posteriorly (fig.14d), or without trace of furca. Furca reduced to finely granulated area with 2 + 2 setulae in one row (fig.14c) or 1 + 1 setulae posteriorly (fig.14d), or to cuticular pocket with 2 + 2 setulae (fig.15b). Head with 2 + 2 posterior pseudocelli. Microsensillum of fourth antennal segment near its base. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head present (fig.11b). Third antennal segment sense organ with one row of guard papillae.

Yoshiiphorura 1
Anal spines present. Body with lateral pseudocelli (fig.1b). Furca vestigial. Furca reduced to cuticular pocket with fig. + 2 or 1 + 1 setulae (fig.13b). Microsensillum of fourth antennal segment located on the basal part of apical third. Postantennal organ fully developed (fig.8b-e). Postantennal organ with 8 or more vesicles (fig.8c-e). Posterior cephalic pseudocelli present (fig.1b). Seta d0 on the head absent (fig.11a). Vesicles in postantennal organ simple (fig.8c).


References