Macrobiotus

Tumanov, Denis V., 2005, Notes on the Tardigrada of Thailand, with a description of Macrobiotus alekseevi sp. nov. (Eutardigrada, Macrobiotidae), Zootaxa 999, pp. 1-16 : 8-9

Macrobiotus sp. gr. furciger ( Figs. 24–37 , Table 2 )

Sample 2 (9 adult specimens and 3 eggs).

Body length of adult animals 292.6–412.3 m ( Figs. 24 , 31 ). Body white. Without eye spots. Cuticle smooth without pores and granulation on legs. Bucco­pharyngeal apparatus of Macrobiotus type ( Figs. 25 , 32 ) (for all dimensions see Table 2 ). Buccal cavity with ten peribuccal lamellae, without anterior band of teeth, with a posterior crown of triangular teeth and a system of three dorsal and three ventral transverse ridges; latero­ventral ridges usually with denticulate anterior margin, medio­ventral ridge is almost broken into several granules ( Figs 26, 27 , 33, 34 ). Several separate rounded teeth situated ventrally between posterior crown of teeth and transverse ridges ( Figs. 27 , 34 ). Buccal tube with typical strengthening bar. Pharyngeal bulb with apophyses, three macroplacoids and a microplacoid. Third macroplacoid with a distinct preterminal constriction. Claws of hufelandi ­ type ( Figs. 28, 29 , 35 ) with minute stalk, distinct distal part of the basal portion and short common tract. Primary and secondary branches diverge below half of claw height, main branches with well developed accessory points. Claws of fourth pair of legs longer than claws of first three pairs of legs. All claws with lunules, which are slightly larger and with undulating margins on fourth pairs of legs. Bar­like cuticular thickenings are present below claw bases of first three pairs of legs ( Fig. 28 ).

Eggs spherical, white, ornamented and laid freely ( Figs. 30 , 36, 37 ). Chorion with conical processes (22 in the optical section at the light microscope) and finely reticulated surface. Chorion processes with bifurcated apices; sometimes one of the branches is also bifurcated. Place of bifurcation situated near to the process apex; branches short and with pointed apices. Surface of processes smooth, sometimes with rare round pores basally. Process bases surrounded with a ring of small dots. Egg dimensions (without processes): 70.3– m; height of processes: 10.7–11.8 m, their basal diameter: 7.4–10.0 m.

Remarks. Macrobiotus sp. belongs to the furciger group of the genus Macrobiotus . This species is mostly similar to the Macrobiotus species stated as M. furciger Murray, 1906 (South African population) in Binda & Rebecchi (1992). Later Prof. Pilato (pers. comm.) pointed out that this South African material belong to a new undescribed species. Macrobiotus sp. differs from M. orcadensis Murray, 1907 (population from Norway) in having no eyes, the terminal points of the egg processes are acuminate while in M. orcadensis they are obtuse, egg processes with a ring of basal dots more evident (Pilato, pers. comm.). Macrobiotus sp. differs from M. pilatoi Binda & Rebecci, 1992 in having thinner buccal tube (pt value 13.3–16.2 in Macrobiotus sp. and 22.8–25.4 in M. pilatoi ), shorter claws (pt value for the claws of the III pair of legs 19.4–23.7 in Macrobiotus sp.

and 29.5–31.5 in M. pilatoi ) and egg chorion with smaller processes and with reticular sculpture between them.

In author’s opinion the furciger­orcadensis complex of species (a group of Macrobiotus species from furciger group with branched chorion processes) needs a careful revision. At present I prefer not to describe this material as a new species in order to avoid possible synonymy. Only redescription of Macrobiotus furciger and M. orcadensis from type locality could resolve the problem.

Figures

FIGURES 24 – 30. Macrobiotus sp. gr. furciger 24 — habitus, 25 — bucco­pharyngeal apparatus, dorsal, 26 — buccal armature, dorsal, 27 — buccal armature, ventral, 28 — claws of the I pair of legs, 29 — claws of the IV pair of legs, 30 — part of the egg surface.

FIGURES 31 – 37. Macrobiotus sp. gr. furciger. 31 — habitus, 32 — bucco­pharyngeal apparatus, dorsal, 33 — buccal armature, dorsal, 34 — buccal armature, ventral, 35 — claws of the I pair of legs, 36, 37 — general appearance of the egg (phase contrast).