Macrobiotus hufelandi, C. A. S. Schultze, 1834

Kaczmarek, Łukasz & Michalczyk, Łukasz, 2017, The Macrobiotus hufelandi group (Tardigrada) revisited, Zootaxa 4363 (1), pp. 101-123 : 116-118

Key to the Macrobiotus hufelandi group

Important notes:

• As M. hibiscus de Barros, 1942 has an uncertain diagnosis and is designated as nomen inquirendum (see above for details), it has not been included in the key.

• Biserov (1990a) reported two egg morphotypes for M. diversus collected from different localities: the egg shell of type “A” (poorly wrinkled and with very small, hardly visible scarce pores) and of type “B” (clearly wrinkled and with numerous pores). Given that these morphotypes may in fact represent two species, they are included in the key separately.

• The presence or absence of eye spots cannot be considered as a definitive differentiating trait as eye spots may have dissolved during the mounting procedure for permanent slides.

1. Oral cavity armature not visible under LM ( lissostomus type)................................................... 2

- Oral cavity armature visible under LM..................................................................... 4

2(1). Small gibbosities on dorsal side of posterior part of the body present............ M. acadianus ( Meyer & Domingue, 2011)

- Small gibbosities on dorsal side of posterior part of the body absent.............................................. 3

3(2). Eyes present, terminal discs of egg processes without teeth................. M. lissostomus Durante Pasa & Maucci, 1979

- Eyes absent, terminal discs of egg processes with long teeth............................... M. julianae ( Meyer, 2012)

4(1). The first band of teeth in the oral cavity not visible in LM..................................................... 5

- The first band of teeth in the oral cavity visible in LM ( hufelandi type)........................................... 6

5(4). Oral cavity armature of the patagonicus type (the 2nd and the 3rd band of teeth visible in LM)......................... 22

- Oral cavity armature of the maculatus type (only the 3rd band of teeth visible in LM)............................... 34

6(4). Egg shell between processes smooth, wrinkled or with granulation ( persimilis type eggs)............................ 7

- Egg shell between processes with pores or regular and well visible reticulation ( maculatus or hufelandi type eggs)........ 15

7(6). Lateral gibbosities on legs IV present...................................................................... 8

- Lateral gibbosities on legs IV absent...................................................................... 9

8(7). Granulation on legs present.................................................. M. halophilus Fontoura et al., 2017

-. Granulation on legs absent..................................................... M. polonicus Pilato et al., 2003

9(7). Flexible undulations under terminal discs of egg processes present.......... M. marlenae Kaczmarek & Michalczyk, 2004

- Flexible undulations under terminal discs of egg processes absent.............................................. 10

10(9). Egg processes without terminal discs or terminal discs very small (enlarged tips).................................. 11

- Egg processes with typically developed terminal discs....................................................... 12

11(10). Egg processes in the form of very thin cones (spine-like, basal diameter <3.5 µm), a crown of basal appendices around egg processes absent.......................................................... M. kristenseni Guidetti et al., 2013

- Egg processes in the form of wide and blunt cones (basal diameter> 10.5 µm), a crown of basal appendices around egg pro- cesses present..................................................................... M. recens Cuénot, 1932

12(10). Lunules IV smoot................................................................................... h 13

- Lunules IV dentate................................................................................... 14

13(12). Granulation on dorso-caudal cuticle present, eyes absent, egg shell wrinkled, terminal discs clearly dentate.......................................................................................... M. hyperboreus Biserov, 1990a

- Granulation on dorso-caudal cuticle absent, eyes present, egg shell smooth, terminal discs without teeth only slightly serrated.............................................................. M. kazmierskii Kaczmarek & Michalczyk, 2009

14(12). Granulation on legs present, egg shell with granulation (which sometimes may form irregular reticular design), egg full diam- eter> 100 µm.............................................................. M. trunovae Biserov et al., 2011

- Granulation on legs absent, egg shell between processes smooth, egg full diameter <80 µm..................................................................................................... M. persimilis Binda & Pilato, 1972

15(6). Egg shell porous ( maculatus type)....................................................................... 16

- Egg shell reticulated ( hufelandi type)..................................................................... 17

16(15). Lunules smooth, egg shell with large round pores around each processes, terminal disc round............................................................................................ M. macrocalix Bertolani & Rebecchi, 1993

- Lunules crenulated, egg shell with numerous small pores scattered on the whole shell, terminal disc pentagona...................................................................................... M. biserovi Bertolani et al., 1996

17(15). Dorsal cuticle with extremely fine granulation.............................................................. 18

- Dorsal cuticle without granulation....................................................................... 19

18(17). Lunules IV dentate, under 30 processes on egg circumference, egg bare diameter> 85.0 µm, egg processes higher than 6.1 µm and wider than 6.5 µm at the base, terminal discs of egg processes over 5.1 µm in diameter...................................................................................................... M. joannae Pilato & Binda, 1983

- Lunules IV smooth, over 31 processes on egg circumference, egg bare diameter <72.0 µm, egg processes lower than 5.6 µm and narrower than 5.5 µm at the base, terminal discs of egg processes under 4.0 µm in diameter................................................................................................... M. punctillus Pilato et al., 1990

19(17). Three separate dorsal teeth in the third band of the oral cavity armature present (lateral and median teeth not fused)................................................................................ M. hufelandi C.A.S. Schultze, 1834

- A single dorsal tooth in third band of the oral cavity armature present (lateral and median teeth fused)................. 20

20(19). Lunules IV smooth.......................................................... M. sapiens Binda & Pilato, 1984

- Lunules IV dentate................................................................................... 21

21(20). Terminal discs of egg processes with regular sharp teeth, process base/height ratio more than 109%................................................................................................... M. iharosi Pilato et al., 1991

- Terminal discs of egg processes with irregular blunt lobes, process base/height ratio less than 77%.................................................................................................. M. seychellensis Biserov, 1994

22(5). Egg shell between processes smooth or porous ( persimilis or maculatus type eggs)................................. 23

- Egg shell between processes regular and well visible reticulation ( hufelandi type eggs)............................. 26

23(22). Egg shell smooth ( persimilis type eggs)............................................. M. patagonicus Maucci, 1988

- Egg shell porous ( maculatus type eggs)................................................................... 24

24(23). A single tooth in the anterior portion of the buccal tube (just behind the oral cavity) present, dorsal cuticle granulated in LM.............................................................................. M. denticulus Dastych, 2002

- A single tooth in the anterior portion of the buccal tube (just behind the oral cavity) absent, dorsal cuticle smooth in LM... 25

25(24). Lunules IV strongly dentate, egg processes short (<7.5 µm) with narrow basses (<7.5 µm), a crown of large peribasal pores absent............................................................................ M. ramoli Dastych, 2005

- Lunules IV smooth, egg processes tall (> 14.0 ìm) with wide basses (> 14.0), a crown of large peribasal pores present....................................................................................... M. glebkai Biserov, 1990

26(22). Terminal discs of egg processes very poorly developed and convex................... M. santoroi Pilato & D'Urso, 1976

- Terminal discs of egg processes normally developed and concave.............................................. 27

27(26). Granulation on legs I–III absent......................................................................... 28

- Granulation on legs I–III present......................................................................... 29

28(27). Lunules IV smooth, eyes absent, ca. 20 processes on the egg circumference, processes higher than 11.0 µm, terminal discs of egg processes wider than 5.0 µm...................................... M. horningi Kaczmarek & Michalczyk, 2017

- Lunules IV dentate, eyes present, ca. 29 processes on the egg circumference, processes lower less than 9.0 µm, terminal discs of egg processes ca. 2.5 µm in diameter.......................................... M. serratus Bertolani et al., 1996

29(27). The 3rd band of teeth in the oral cavity armature composed of a single long tooth............. M. sottilei Pilato et al., 2012

- The 3rd band of teeth in the oral cavity armature composed of three separate teeth.................................. 30

30(29). Egg processes flexible and without terminal discs................................. M. dariae Pilato & Bertolani, 2004

- Egg processes rigid and with terminal discs................................................................ 31

31(30). Terminal discs of egg processes with a smooth edge.................................. M. personatus Biserov, 1990b

- Terminal discs of egg processes with a jagged or ragged edge.................................................. 32

32(31). A ring of large and elongated pores around each egg process present............................................ 33

- A ring of large and elongated pores around each egg process absent............... M. sandrae Bertolani & Rebecchi, 1993

33(32). The 2nd macroplacoid with a subterminal constriction, egg full diameter <71 µm, processes lower than 6.1 µm............................................................................... M. terminalis Bertolani & Rebecchi, 1993

- The 2nd macroplacoid without a subterminal constriction, egg full diameter> 89 µm, processes higher than 6.4 µm................................................................................. M. vladimiri Bertolani et al., 2011a

34(5). Egg shell between processes smooth or porous ( persimilis or maculatus type eggs)................................. 35

- Egg shell between processes covered with a (sometimes poorly visible) reticulum ( hufelandi type eggs)................ 40

35(34). Egg shell between processes smooth ( persimilis type)........................................................ 36

- Egg shell between processes porous ( maculatus type)........................................................ 38

36(35). Dorsal cuticle and legs with gibbosities, egg processes flexible and without terminal discs. M. semmelweisi Pilato et al., 2006

- Dorsal cuticle and legs without gibbosities, egg processes not flexible and with terminal discs........................ 37

37(36). Pores on cuticle, granulation on legs and teeth on lunules IV absent, terminal discs of egg processes with very long teeth............................................................................... M. anemone Meyer et al., 2014

-. Pores on cuticle, granulation on legs and teeth on lunules IV present, terminal discs of egg processes with very short teeth........................................................................... M. naskreckii Bąkowski et al., 2016

38(37). Lunules IV smooth, cuticular pores 3.0–8.0 µm in diameter............................... M. maculatus Iharos, 1973

- Lunules IV dentate, cuticular pores under 2.0 µm in diameter.................................................. 39

39(38). Egg shell between processes slightly wrinkled and with very small and scarce pores not grouped around or on bases of pro- cesses............................................................ M. diversus “morphotype A” Biserov, 1990a

- Egg shell between processes clearly wrinkled and with large and numerous pores which are present also around bases and on the processes...................................................... M. diversus “morphotype B” Biserov, 1990a

40(34). Lunules IV dentate or crenate........................................................................... 41

- Lunules IV smooth................................................................................... 45

41(40). Terminal discs of egg processes with long flexible filaments.................................................. 42

-. Terminal discs of egg processes without long flexible filaments................................................ 43

42(41). Seven paired patches of fine granulation of the dorso-lateral cuticle, egg processes discs with teeth and with single filaments on some of the discs............................................................ M. paulinae Stec et al., 2015

- Dorsal cuticle smooth, egg processes discs without teeth and with large number of filaments on each disc..................................................................................... M. polypiformis Roszkowska et al., 2017

43(41). The pt of the stylet support insertion point higher than 72.5, terminal discs of egg processes convex and smooth, under 24 pro- cesses on the egg circumference.................................................. M. martini Bartels et al., 2009

- The pt of the stylet support insertion point lower than 71.5, terminal discs of processes concave and with teeth, over 29 pro- cesses on the egg circumference......................................................................... 44

44(43). Cuticular pores absent, pt of the stylet support insertion point higher than 70.5, the 1 st macroplacoid longer than 7.5 µm (pt> 24.0), the macroplacoid row longer than 12.0 µm (pt> 38.0), placoid row longer than 14.0 (pt> 45.0), eyes absent...................................................................................... M. madegassus Maucci, 1993

- Cuticular pores present, pt of the stylet support insertion point lower than 69.9, the 1 st macroplacoid shorter than 6.7 µm (pt <21.0), the macroplacoid row shorter than 11.0 µm (pt <34.0), the placoid row shorter than 13.0 (pt <39.0), eyes present................................................................................ M. modestus Pilato & Lisi, 2009

45(40). Granulation on legs IV absent, egg processes without terminal discs but with laterally flattened terminal portions........................................................................................ M. scoticus Stec et al., 2017

-. Granulation on legs IV present, egg processes with typical terminal discs........................................ 46

46(45). Granulation on legs I–III present, pt of the stylet support insertion point under 71.5 ....... M. humilis Binda & Pilato, 2001

- Granulation on legs I–III absent, pt of the stylet support insertion point over 73.9 .................................. 47

47(46). Buccal tube longer than 40.0, the 1 st macroplacoid longer than 10.5 µm, macroplacoid and placoid rows longer than 17.0 µm and 19.9 µm respectively, egg surface with only one stripe of mesh around each process... M. rawsoni Horning et al., 1978

- Buccal tube shorter than 35.0 µm, the 1 st macroplacoid shorter than 9.0 µm, macroplacoid and placoid rows shorter than 16.0 µm and 18.7 µm respectively, egg surface with uniform reticulation.................... M. almadai Fontoura et al., 2008