Macrobiotus siamensis, Tumanov, Denis V., 2006

Tumanov, Denis V., 2006, Macrobiotus siamensis sp. n. (Eutardigrada, Macrobiotidae) from Thailand (Asia), Zootaxa 1202, pp. 53-59 : 54-58

publication ID

https://doi.org/ 10.5281/zenodo.172320

DOI

https://doi.org/10.5281/zenodo.5665592

persistent identifier

https://treatment.plazi.org/id/91728794-D61A-FF88-A068-FD5CE2E4FA51

treatment provided by

Plazi

scientific name

Macrobiotus siamensis
status

sp. nov.

Macrobiotus siamensis View in CoL sp. n.

( Figs. 1–14 View FIGURES 1 – 7 View FIGURES 8 – 14 , Table 1 View TABLE 1 )

= Macrobiotus View in CoL sp. gr. furciger ( Tumanov 2005) View in CoL

Type material

Holotype: Slide number 201(49) (sex indet.). Collected by Dr. V. R. Alekseev (Zoological Institute of the Russian Academy of Sciences, St. Petersburg), 0 1.02.2003, Thailand. Paratypes: Slides number 201(37, 46, 50, 51) from the same locality. Holotype and paratypes are preserved at the Zoological Institute of the Russian Academy of Sciences, St.Petersburg, Russia.

Type locality: Thailand, Nam­Nao National Park (Phetchabun province and Chaiyaphum province), near the park’s headquarters, fallen bamboo leaves in a pit near a little stream. Nine adult specimens and three eggs (one with developed embryo) were found.

Description

Body length of adult animals 292.6–412.3 m ( Figs. 1 View FIGURES 1 – 7 , 8 View FIGURES 8 – 14 ). Body white (colourless). Without eye spots. Cuticle smooth without pores and granulation. Bucco­pharyngeal apparatus of Macrobiotus type ( Figs. 2 View FIGURES 1 – 7 , 9 View FIGURES 8 – 14 ) (for all dimensions see Table 1 View TABLE 1 ). Buccal cavity with ten peribuccal lamellae, very poorly developed anterior band of teeth (scarcely visible even in the largest specimens), 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. 3, 4 View FIGURES 1 – 7 , 10, 11 View FIGURES 8 – 14 ). Several separate rounded teeth situated ventrally between posterior crown of teeth and transverse ridges. 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. 5, 6 View FIGURES 1 – 7 , 12 View FIGURES 8 – 14 ) 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. 5 View FIGURES 1 – 7 ).

Eggs spherical, white, ornamented and laid freely ( Figs. 7 View FIGURES 1 – 7 , 13, 14 View FIGURES 8 – 14 ). Chorion with conical processes (22 in the optical section at the light microscope), with bifurcated apices (sometimes one of the branches is also bifurcated). Place of bifurcation situated near the process apex, branches are short and with pointed apices. Surface of processes smooth, rarely with poorly developed light areas (pores?). Process bases surrounded with a ring of small dots. Egg surface between processes with irregularly distributed broken ridges, forming poorly developed reticulation. Egg diameter (without processes): 70.3– m; height of processes: 10.7–11.8 m, their basal diameter: 7.4–10.0 m.

Ss = distance from cephalic end of buccal tube to insertion point of stylet supports. Supplementary measurements for holotype: length of strengthening bar on buccal tube: 27.4 m, lunules on claws of the fourth pair of legs: 4.4 x 2.1 m

Remarks

Macrobiotus siamensis View in CoL sp. n. belongs to the furciger View in CoL group and is most similar to Macrobiotus sicheli Binda, Pilato and Lisi, 2005 View in CoL in having short apical branches of egg processes. Macrobiotus siamensis View in CoL sp. n. differs from M. sicheli View in CoL in absence of eyes, smooth cuticle, stylet supports inserted on the buccal tube in a more cephalic position (pt values: 77.1–78.8 in M. siamensis View in CoL sp. n. and 79.3–80.0 in M. sicheli View in CoL ), thinner buccal tube (pt values: 13.3–16.2 in M. siamensis View in CoL sp. n. and 16.4–18.3 in M. sicheli View in CoL ), eggs with longer processes (10.7–11.8 m in M. siamensis View in CoL sp. n. and 6.5–7.8 m in M. sicheli View in CoL ) and less developed sculpture between them.

Macrobiotus siamensis View in CoL sp. n. differs from Macrobiotus pilatoi Binda and Rebecci, 1992 View in CoL in having thinner buccal tube (pt value 13.3–16.2 in M. siamensis View in CoL sp. n. and 22.8–25.4 in M. pilatoi View in CoL ), shorter claws (pt value for the claws of the III pair of legs 19.4–23.7 in M. siamensis View in CoL sp. n. and 29.5–31.5 in M. pilatoi View in CoL ) and egg chorion with smaller processes (10.7–11.8 m in M. siamensis View in CoL sp. n. and 15 m in M. pilatoi View in CoL ) and with different sculpture between them.

Macrobiotus siamensis View in CoL sp. n. differs from Macrobiotus furciger View in CoL in absence of eyes, slightly wider buccal tube (pt value 13.3–16.2 in M. siamensis View in CoL sp. n. and 12.7–13.6 in M. furciger View in CoL ), shorter claws and smaller eggs with short branches of processes and with different sculpture between them.

Macrobiotus siamensis View in CoL sp. n. differs from Macrobiotus aradasi Binda, Pilato and Lisi, 2005 View in CoL in absence of eyes, wider buccal tube (pt value 13.3–16.2 in M. siamensis View in CoL sp. n. and 11.7–11.8 in M. aradasi View in CoL ), stylet supports inserted on the buccal tube in a more caudal position (pt values: 77.1–78.8 in M. siamensis View in CoL sp. n. and 72.0– 72.8 in M. aradasi View in CoL ) and smaller eggs with shorter branches of processes and with different sculpture between them.

Macrobiotus siamensis View in CoL sp. n. differs from Macrobiotus divergens Binda, Pilato and Lisi, 2005 View in CoL in having stylet supports inserted on the buccal tube in a more caudal position (pt values: 77.1–78.8 in M. siamensis View in CoL sp. n. and 75.5–76.2 in M. divergens View in CoL ), eggs with more dense distribution of processes, short branches of processes and different sculpture between them.

Macrobiotus siamensis View in CoL sp. n. differs from Macrobiotus orcadensis Murray, 1907 View in CoL (population from Norway) in absence of eyes, the terminal points of the egg processes are acuminate while in M. orcadensis View in CoL they are obtuse, egg processes with a ring of basal dots more evident (Pilato, pers. comm.).

TABLE 1. Summary of morphometric data for Macrobiotus siamensis sp. n. (n = 9).

Character Holotype Smallest specimen Largest specimen Mean (Range)
body length (m) 412.3 292.6 412.3 351.6 (292.6–412.3)
buccal tube length (m) 44.4 41.8 44.4 42.4 (38.9–48.1)
Ss (m) 34.8 32.9 34.8 33 (30–37.4)
pt Ss (%) 78.3 78.8 78.3 77.9 (77.1–78.8)
outer buccal tube width (m) 6.4 6.7 6.4 6.4 (5.2–7.4)
pt of outer buccal tube width (%) 14.5 15.9 14.5 15.1 (13.3–16.2)
Placoid row length (m) 23.7 21.5 23.7 21.1 (18.1–25.9)
pt of placoid row length (%) 53.3 51.3 53.3 49.6 (44.9–53.8)
Macroplacoid row length (m) 18.5 16.3 18.5 16.2 (13.7–20)
pt of macroplacoid row length (%) 41.7 38.9 41.7 38.2 (34.9–41.7)
1st macroplacoid length (m) 4.8 4.4 4.8 4.6 (3.7–6.4)
pt of 1st macroplacoid length (%) 10.8 10.6 10.8 10.8 (8.5–13.2)
2nd macroplacoid length (m) 4.2 3.7 4.2 3.8 (3.2–4.4)
pt of 2nd macroplacoid length (%) 9.5 8.8 9.5 9 (7.6–9.6)
3rd macroplacoid length (m) 5.7 5.0 5.7 4.9 (3.8–6.7)
pt of 3rd macroplacoid length (%) 12.8 12.0 12.8 11.4 (9.5–13.8)
Microplacoid length (m) 4.4 4.1 4.4 4 (3.3–5)
pt of microplacoid length (%) 10.0 9.7 10.0 9.3 (7.7–11)
External claw length, leg I (m) 8.9 8.1 8.9 8.5 (7.8–9.6)
pt of external claw length, leg I (%) 20.0 19.5 20.0 20 (18.7–21.1)
External claw length, leg III (m) 9.6 8.9 9.6 9.3 (8.5–11.1)
pt of external claw length, leg III (%) 21.7 21.2 21.7 21.8 (19.4–23.7)
External claw length, leg IV (m) 11.8 11.1 11.8 11.1 (9.6–11.8)
pt of external claw length, leg IV (%) 26.7 26.5 26.7 26.4 (24.2–28.4)

Kingdom

Animalia

Phylum

Tardigrada

Class

Eutardigrada

Order

Parachela

Family

Macrobiotidae

Genus

Macrobiotus

Loc

Macrobiotus siamensis

Tumanov, Denis V. 2006
2006
Loc

furciger (

Tumanov 2005
2005
Loc

Macrobiotus sicheli

Binda, Pilato and Lisi 2005
2005
Loc

Macrobiotus aradasi

Binda, Pilato and Lisi 2005
2005
Loc

Macrobiotus divergens

Binda, Pilato and Lisi 2005
2005
Loc

Macrobiotus pilatoi

Binda and Rebecci 1992
1992
Loc

Macrobiotus orcadensis

Murray 1907
1907
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