Macrobiotidae

Pilato, Giovanni & Binda, Maria Grazia, 2010, Definition of families, subfamilies, genera and subgenera of the Eutardigrada, and keys to their identification, Zootaxa 2404, pp. 1-54 : 49

Key to the genera of Macrobiotidae

1. Claws on the fourth pair of legs reduced to granular rudiments or absent; claws on the first three pairs of legs of the Xerobiotus type ( Fig. 20 E) ............................................................................................................ Pseudohexapodibius

- Claws on the fourth pair of legs normally developed.................................................................................................. 2

2. Bucco-pharyngeal apparatus with rigid tube ................................................................................................................ 3

- Bucco-pharyngeal apparatus with the tube subdivided into an anterior rigid and a flexible caudal tract .................. 11

3. Claws of the hufelandi type ( Figs. 1 F, 20C); peribuccal lamellae may be present or absent ....................................... 4

- Claws different; peribuccal lamellae present................................................................................................................ 9

4. Dorsal wall of the buccal tube smooth (without ridge or hook). Branches of the stylet furcae typically shaped ( Fig. 4 A), i. e., with thickened, swollen, rounded apices ...................................................................................................... 5

- Dorsal wall of the buccal tube with a dorsal ridge or hook. Branches of the stylet furcae with thickened but not swol- len apices ( Fig. 4 B) ....................................................................................................................................................... 8

5. Double systems of transverse ridges present in the buccal armature ( Fig. 21 B)..................................... Famelobiotus

- Only one (well or less developed) system of dorsal and ventral transverse ridges present in the buccal armature..... 6

6. Peribuccal lamellae absent. Peribuccal papulae present. Buccal tube narrow or very narrow; stylet supports inserted on the bucal tube at 48–73 % of its length in the known species ( Fig. 22 C, D)........................................... Minibiotus

- Peribuccal lamellae present. Stylet supports inserted on the buccal tube at well over half its length ( Fig. 21 A) ........ 7

7. All the following characters present: claws of the hufelandi type; cuticle without pores; buccal tube wide; three rod- shaped macroplacoids; microplacoid distant from the third macroplacoid (more than its length) ( Fig. 21 C); eggs with conical processes and areolated egg shell .......................................................................................... Paramacrobiotu s

- Claws of the hufelandi type. At least one of the above indicated characters is different; in particular, when three macroplacoids and microplacoid are present, the microplacoid is not so distant from the third macroplacoid ( Fig. 21 A) ........................................................................................................................................................... Macrobiotus

8. Dorsal wall of the buccal tube and anterior tract of the ventral lamina with a ridge but without a hook ( Fig. 22 A)..... ................................................................................................................................................................... Adorybiotus

- Both buccal tube dorsal wall and anterior tract of the ventral lamina with a hook ( Fig. 22 B) ..................... Richtersius

9. Claws of the Xerobiotus type ( Fig. 20 E) ....................................................................................................... Xerobiotus

- Claws of the Calcarobiotus type, at least on the first three pairs of legs ( Fig. 20 A,B) ............................................. 10

10. Claws of the Calcarobiotus type with very long accessory points connected to the primary branch by a flexible tract ( Fig. 20 B) ...................................................................................................................................................... Schusterius

- Accessory points normally developed ( Fig. 20 A) ................................................................................... Calcarobiotus (see below the key to the subgenera)

11. Claws of the Biserovus type ( Fig. 20 F). Peribuccal lamellae present ( Fig. 23 A).......................................... Biserovus

- Claws of the hufelandi type ( Figs. 1 F, 20C). Peribuccal lamellae present or absent.................................................. 12

12. Peribuccal lamellae absent, peribuccal papulae present ( Fig. 23 B). Branches of the stylet furcae typically shaped ( Fig. 23 B) ....................................................................................................................................................... Minilentus

- Peribuccal lamellae present ( Fig. 23 C). Branches of the stylet furcae arched and converging backwards ( Figs. 4 C, 23C)............................................................................................................................................................. Insuetifurca

Figures

FIGURE 1. Some types of claws of the Eutardigrada. A, Milnesiidae; B, Hexapodibius (Calohypsibiidae); C, Microhypsibiidae; D, Eohypsibiidae; E, Hypsibiu s (Hypsibiidae); F, Macrobiotus (Macrobiotidae). ap = accessory points; bs = basal section; bth = basal thickening; ds = distal section; lu = lunula; pb = primary brach; s = stem; sb = secondary branch; sp = spur. (B, from Binda & Pilato, 1969; C, from Pilato, 1998).

FIGURE 4. Stylet furcae shapes. A, typically-shaped furcae (the basal portion is enlarged and has two caudal branches with thickened, swollen, rounded apices); B, Richtersius type (the branches, very robust, have thickened but neither swollen nor rounded apices); C, Insuetifurca type (the branches are arched and converging backwards); D, Eohypsibius type (the branches are arched, without particularly swollen apices); E, Mesocrista type (the basal portion is not very enlarged and the branches have thickened, swollen, rounded apices); F, Platicrista type (the branches are pointing backwards instead of backwards and sideways, and on lateral view they are spoon like and tapering at their apices); G, Astatumen type (the branches are very short and taper at their apices); H, Itaquascon type (the branches are very short and without swollen apices); I, Milnesium type (triangular in shape without long branches pointing backwards and sideways). (A, E, F, G from Pilato, 1987. C, from Guidetti & Pilato, 2003).

FIGURE 20. Claws of Macrobiotidae. A, B: Calcarobiotus type (A, of Calcarobiotu s; B, of Schusterius); C, D, Macrobiotus (or hufelandi) type (C, of Macrobiotus; D, of Insuetifurca); E, Xerobiotus type (E, of Xerobiotus; F, of Biserovus). (B, from Kaczmarek & Michalczyk, 2006; C, from Binda & Rebecchi, 1992; E, from Binda & Pilato, 1971; F, from Guidetti & Pilato, 2003).

FIGURE 21. Bucco-pharyngeal apparatuses of the Macrobiotus model, Macrobiotus type. A, of Macrobiotus; B, of Famelobiotus; C, of Paramacrobiotus. tr = transverse ridges; tr 1 = anterior system of transverse ridges; tr 2 = posterior system of transverse ridges. (A, from Pilato & Binda 1983 b; B, from Pilato & Lisi, 2004 a; C, from Binda & Pilato, 2001).

FIGURE 22. Bucco-pharyngeal apparatuses of the Macrobiotus model. A, Adorybiotus type; B, Richtersius type; C, D, Macrobiotus type, Minibiotus variant (C, in lateral view; D, in ventral view). v = peribuccal velum. (A, B, from Pilato & Binda, 1987 b; C, from Pilato et al., 2003).

FIGURE 23. Bucco-pharyngeal apparatuses of the Biserovus model, Biserovus type: A, of Biserovus; B, of Minilentus; C, of Insuetifurca. pl = peribuccal lamellae; pp = peribuccal papulae; stf = stylet furcae. (C, from Guidetti & Pilato, 2003).