Tardigrades of North Carolina
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View PDFMacrobiotidae Members: 3 NC Records

Mesobiotus harmsworthi (Murray, 1907) - No Common Name


Habitus, PC Specimen from Spitzbergen Kaczmarek et al. 2018
Taxonomy
Class: EutardigradaOrder: Parachela Family: Macrobiotidae Checklist Number: 1820.0 Synonym: Macrobiotus harmsworthi
Taxonomic Comments: Transferred from Macrobiotus by Vecchi et al. 2016. Redescribed with integrative taxonomy and split into pseudocryptic species by Kaczmarek et al. 2018.
Species Notes: Terrestrial. M. harmsworthi proper is a northern Eurasian species. These old records from North Carolina are likely to be Mesobiotus n. species which needs fresh specimens for a complete description. See Mesobiotus n. species account.
Identification
Online resources:Online Photographs: Google, GBIF                                                                                 
Species Description: Body white in living specimens and transparent after fixation (Fig 2A and 2B). Eyes present. Cuticle smooth, i.e., without gibbosities, papillae, spines, sculpture or pores. Granulation present only on the external surface of all legs (Fig 2C2F). Bucco-pharyngeal apparatus of the Macrobiotus type (Fig 3A and 3B), with the ventral lamina and ten peribuccal lamellae. Mouth antero-ventral. The oral cavity armature well developed and composed of three bands of teeth (Fig 3C–3F). The first band of teeth iscomposed of numerous small granules arranged in aseveral rows situated anteriorly in the oral cavity, just behind the bases of the peribuccal lamellae (Fig 3C and 3F; arrowhead). The band ishardly detectible under PCM in small specimens and clearly visible in large individuals. The second band of teeth issituated between the ring fold and the third band of teeth and comprises ridges parallel to the main axis of the buccal tube and additional teeth between and below them, larger than those in the first band (Fig 3C, 3E and 3F; arrow). The teeth of the third band are located within the posterior portion of the oral cavity, between the second band of teeth and the buccal tube opening (Fig 3C–3F; indented arrowhead). The third band of teeth isdivided into the dorsal and the ventral portion. Under PCM, both dorsal and ventral teeth are visible as two lateral and one median transverse ridges (Fig 3C–3F; indented arrowhead). Pharyngeal bulb spherical, with triangular apophyses, three rod-shaped macroplacoids and atriangular microplacoid. Macroplacoid length sequence 2<31. The first macroplacoid narroweranteriorly, the second without constrictions and the third with asmall, subterminal constriction (Fig 3G and 3H; empty arrowhead). Claws of the Mesobiotus type, robust (Fig 4A–4D). Primary branches with distinct accessory points. Accessory point on claws IV are larger and more protruding than in most macrobiotids (Fig 4B and 4D; arrowheads). Lunules under claws I–III smooth and slightly dentated under claws IV (Fig 4B and 4D; empty arrowhead). Thin cuticular bars under claws I–III present (Fig 4A, arrow). Other cuticular structures on legs absent.

Eggs: Laid freely, white, spherical and ornamented, with processes and delicate areolation (Figs 5–7). Egg processes in the shape of wide cones (Fig 6A6H). The cones can be slightly concave (Figs 5B, 5C, 6B and 6C) or sigmoidal, i.e., with a slightly swollen base and anarrowed apex (Fig 6D). The processes with asingle sharp (Fig 6A and 6E) or slightly blunt (Fig 6B and 6F) apex, only occasionally bifurcated (Fig 6D, 6G and 6H). In PCM, processes reticulated with mesh size 0.5–2.0 μm in diameter, evidently larger near the process base and apex (Fig 6A–6D). Sometimes, instead of several large meshes, asingle very large bubble ispresent in the apex (Fig 6A–6D, arrows). In SEM, processes smooth, but with well visible small pores at the bases and inside the areoles close to the processes (Figs 6E–6H, 7C and 7D, arrows). Each process surrounded by five or six areolae delimited by thin brims (Fig 7A–7D). The brims are very often discontinuous, thus areolae are not always fully formed (Fig 7A and 7C, arrowheads). Surface inside the areolae with clearly visible wrinkles, both in PCM (Fig 7A and 7B) and in SEM (Fig 7C and 7D). Occasionally, the wrinkles may form asmall whirl in the areola centre (Fig 7C, empty arrowhead).

-Kaczmarek et al. 2018
Body Length: 275-489 microns
Key Characters: The M. harmsworthi group is characterized by three clearly separated macroplacoids in the shape of short, rounded rods and adistinct microplacoid situated very close to them, as well as by conical or hemispherical egg processes. M. harmsworthi proper has eye spots, a smooth cuticle, large and protruding accessory points on claws IV. The egg has areolation on the egg surface and the egg process includes large bubble at the tip and reticulations that are larger at the base of the process. Other details of buccal armature are taxonomically valuable characters.
Key Character Images
ID Requirements: Identifiable only by close inspection of key characters or by DNA analysis.
Distribution in North Carolina
Distribution:
County Map: Clicking on a county returns the records for the species in that county.
Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Habitats and Life History
Habitats: Moss and other terrestrial habitats.
Abundance: Common in Nelson's Roan Mt. inventory.
Diet: Carnivorous or omnivorous.
Reproduction: Ornamented eggs deposited externally.
Observation Methods: PC, DIC, and SEM.
Wikipedia

 Photo Gallery for Mesobiotus harmsworthi - No common name

Photos: 8

Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Egg, SEM Specimen from Spitzbergen Kaczmarek et al. 2018		Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Egg, PC Specimen from Spitzbergen Kaczmarek et al. 2018
Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Claws with large accessory points, PC Specimen from Spitzbergen Kaczmarek et al. 2018		Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Buccal apparatus, PC Specimen from Spitzbergen Kaczmarek et al. 2018
Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Details of placoids, PC Specimen from Spitzbergen Kaczmarek et al. 2018		Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Buccal armature, PC Specimen from Spitzbergen Kaczmarek et al. 2018
Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Habitus, PC Specimen from Spitzbergen Kaczmarek et al. 2018		Recorded by: Riggin on 1958-08-01
Swain Co.
Comment: Egg process, PC Specimen from Spitzbergen Kaczmarek et al. 2018