Macrobiotus reinhardti, Michalczyk, Łukasz & Kaczmarek, Łukasz, 2003

Michalczyk, Łukasz & Kaczmarek, Łukasz, 2003, A description of the new tardigrade Macrobiotus reinhardti (Eutardigrada: Macrobiotidae, harmsworthi group) with some remarks on the oral cavity armature within the genus Macrobiotus Schultze, Zootaxa 331, pp. 1-24 : 3-14

Macrobiotus reinhardti sp. nov.

( Figs 1–50 , 51–52 , 55a–58b)

Description

Adult (holotype): Body length 468.4 ( Figs 1–5 ). Body transparent/white, eyes in posterior position. Cuticle without pores. Very fine and thin granulation on whole cuticle (but more dense on dorsal side of body) visible in SEM only. In LM cuticle smooth. Hind legs with fine, regular granulation (LM and SEM). Legs I to III smooth (LM).

Bucco­pharyngeal apparatus of Macrobiotus type ( Figs 6–11 ). Mouth antero­ventral, surrounded by ring of 10 peribuccal lamellae. Oral cavity armature of harmsworthi ­ type ( Figs 12–16 , 51–52 , 55a–58b). For its description see the later discussion of this type (pages 15–17).

Buccal tube 54.2 long and 6.7 [12.3] wide ( Figs 6–11 ). With one bend in anterior part of tube (visible in lateral view). Stylet supports inserted on buccal tube at 43.7 [80.7]. Ventral buccal lamina 38.9 [65.0] long. Pharyngeal bulb slightly oval with distinct, triangular apophyses, three macroplacoids and microplacoid. First macroplacoid thinner anteriorly, 8.6 [15.8] long, second oval, 6.7 [12.3] long, both without constriction. Third macroplacoid 8.6 [15.8] long, with distinct constriction in terminal part. Microplacoid large, tearshaped 4.8 [8.8]. Macroplacoid row 26.6 [49.1] long. Placoid row 32.3 [59.6] long.

Claws of hufelandi ­ type, stout ( Figs 17­19 ). Primary branches with distinct accessory points. Lunules on all legs smooth, better developed on IV pair of legs. Lunules larger on internal claws of IV pair of legs. Primary branch with basal claw of I pair of legs 12.4 [22.8] long, secondary branch 11.4 [21.1] long, II pb. 13.3 [24.6], sb. 11.4 [21.1]; III pb. 13.3 [24.6], sb. 11.4 [21.1]; IV pb. 15.2 [28.1], sb 12.4 [22.8]. Bars and other cuticular structures on legs absent.

Egg: Transparent/white, laid freely ( Figs 20–50 ). Spherical, with conical processes (9 on circumference of egg). Diameter without processes 80.8, with processes 134.0. Processes 24.7–28.5 high and 27.6–28.5 wide at the base, with slender, short, flexible distal portion ( Figs 30–44 ). Surface between processes wrinkled, but with neither granulation nor areolation; wrinkles not always clearly visible in LM. Processes built of double wall with transverse supporting walls that form ‘cells’ visible in LM as reticular design ( Fig. 50 ). Large round ‘cell’ (seen as bubble in LM) in upper part of each process. Smaller ‘cells’ (bubbles) also visible in the flexible portion, over large ‘cell’. Near base of each process, bands of pores (about 0,5 in diameter) in external and internal walls and smaller pores (0,1–0,3 in diameter) in surface between processes (visible only in SEM).

Processes have the same type of structure but limited variability of shapes and sizes of some characters was noted and is shown in Figs 32­40 .

Remarks

Results of simple statistical analysis of measurements and pt values of selected morphological structures for 15 randomly chosen specimens and all eggs are given in Tables 1­4 .

Among 30 randomly chosen mounted specimens, only 13 had eyes (43%).

Type locality

Greek part of Cyprus; Tordos Mts., southern slope of Mt. Olymp, near the top (about 1700 m asl); moss samples from rock, tree and soil; 27.09.2002; leg. Barbara Kaczmarek.

CHARACTER MIN MAX MEAN SD N

Body length 864.9 1041.0 951.58 49.99 15

Level of the stylet support insertion point 77.6 80.7 79.30 0.94 15

Buccal tube external width 10.4 14.9 12.27 1.25 15

Macroplacoid 1 length 12.5 18.0 16.07 1.69 15

Macroplacoid 2 length 8.5 16.4 12.84 2.22 15

Macroplacoid 3 length 13.5 19.4 15.98 1.64 15

Microplacoid length 6.9 9.8 8.62 0.85 15

......continued on the next page CHARACTER MIN MAX MEAN SD N

Diameter of egg without processes 74.1 85.5 79.06 3.55 9

Diameter of egg with processes 123.5 147.3 133.53 6.84 9

Processes height 20.0 34.2 27.16 2.97 27

Processes base width 23.8 28.5 26.35 1.48 27

Number of processes on the circumference of egg 8 10 9.2 0.7 9 Type depositories

Holotype and 27 paratypes (14 adults and 13 eggs) are preserved at the Zoological Museum of the Jagiellonian University, ul. Ingardena 6, 30­060 Kraków, Poland; 18 paratypes (adults and eggs) are preserved in the collection of Ł. Michalczyk (Jagiellonian University); 23 paratypes (adults and eggs) are preserved at the Department of Animal Taxonomy and Ecology, A. Mickiewicz University, Poznań.

Etymology

We take great pleasure in dedicating this species in honour of the eminent Danish tardigradologist, Professor Reinhardt Møbjerg Kristensen.

Differential diagnosis

Macrobiotus reinhardti sp. nov. belongs to the harmsworthi group which contains similar species that have three macroplacoids describing an arch and a microplacoid in the pharyngeal bulb, cuticle without pores and lay eggs with conical processes. The new species is most similar to Macrobiotus stellaris Du Bois­Reymond Marcus , but differs from it by having a narrower buccal tube (pt ~ 12.5 in. M. reinhardti sp. nov. and ~20.0 in M. stellaris ), smaller microplacoid, larger pharyngeal apophyses and the posterior position of eyes when they occur (anterior in M. stellaris ). Additionally, eggs of M. reinhardti sp. nov. have only one large ‘cell’ (bubble) in the upper part of the processes, while in M. stellaris one or more ‘cells’ (bubbles) are found on the top of processes. Egg processes of M. stellaris also have much longer flexible endings that can form filaments (filaments are absent in M. reinhardti sp. nov.).

Figures

FIGURE 1. Macrobiotus reinhardti sp. nov. – habitus (paratype).

FIGURES 2 – 3. Macrobiotus reinhardti sp. nov. – habitus; 2 – ventral view, 3 – middle section view (paratype). (DIC)

FIGURES 4 – 5. Macrobiotus reinhardti sp. nov. – habitus; 4 – dorsal view, 5 – ventral view (paratypes). (SEM)

FIGURES 6 – 7. Macrobiotus reinhardti sp. nov. – buccal apparatus; 6 – ventral view, 7 – dorsal view; arrows indicate three bands of teeth in the oral cavity (holotype).

FIGURES 8 – 16. Macrobiotus reinhardti sp. nov. 8 ­ 11 – sequential sections of buccal apparatus (from ventral to dorsal view); 12 ­ 16 – sequential sections of the oral cavity (from ventral to dorsal view), arrows indicate bands of teeth (paratype). (DIC)

FIGURE 17. Macrobiotus reinhardti sp. nov. – claws of the fourth pair of legs (left – internal, right – external), note larger lunula on the internal claw (holotype).

FIGURES 18 – 19. Macrobiotus reinhardti sp. nov. – hind legs; 18 – dorsal view, note fine granulation on the legs; 19 – ventral view, note larger lunules on the internal claws (paratypes). (SEM)

FIGURE 20. Macrobiotus reinhardti sp. nov. – egg, a semi schematic drawing with three fully drawn processes, ‘ I­IX’ – nine processes on the circumference of the egg.

FIGURES 51 – 54. Two main types of oral (buccal) cavity armature within the genus Macrobiotus Schultze. 51 – 52 – harmsworthi ­ type (51 – ventral view; 52 – dorsal view); 53 – 54 – hufelandi ­ type (53 – ventral view; 54 – dorsal view). Arrows indicate three bands of teeth (I­III). (Not scaled)

FIGURES 30 – 31. Macrobiotus reinhardti sp. nov. – process on the circumference of egg; 30 – surface, 31 – middle section (DIC).

FIGURES 32 – 40. Macrobiotus reinhardti sp. nov. – variability of processes, each process comes from a different egg; focused on the largest ‘ cell’ (bubble) on each figure. (DIC)

FIGURES 41 – 44. Macrobiotus reinhardti sp. nov. – processes and surfaces of eggs; note arrow on fig. 42 indicates a pore in the basal portion of process, arrow on fig. 43 indicates wrinkled surface between processes and arrow on fig. 44 indicates smaller pore in the surface between processes. (SEM)

FIGURES 45 – 50. Macrobiotus reinhardti sp. nov. – intentionally damaged egg; 45 – general view, 46 ­ 48 – the sequence of closer views of the internal structure of processes; 49 – single process; 50 – torn wall of process; arrows on figs 48 – 49 indicate pores in the internal wall of processes, arrows on fig. 50 indicate external and internal walls of process. (SEM)