Tardigrades of North Carolina
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View PDFItaquasconidae Members: 2 NC Records

Mesocrista spitzbergensis (Richters, 1903) - No Common Name


Habitus, DIC
Taxonomy
Class: EutardigradaOrder: Parachela Family: ItaquasconidaeSubfamily: Itaquasconinae Checklist Number: 1310.0 Synonym: Mesocrista cf. spitzbergensis (Bartels et al. 2021)
Taxonomic Comments: Morphologically matches species from Svalbard amended by Gasiorek et al. 2016 with integrative taxonomy. No DNA data for smokies population. Family designation follows Tumanov & Tsvetkova (2023).
Species Notes: Terrestrial. Has been reported from scattered locations around the world and US, but DNA is needed to verify diagnosis.
Identification
Online resources:Online Photographs: Google, GBIF                                                                                 
Species Description: Genus diagnosis: Peribuccal structures absent. Apophyses for the insertion of stylet muscles in the shape of wide and flat ridges symmetrical with respect to the frontal plane and with welldeveloped
caudal processes pointing diagonally (backwards and sideways). Bucco-pharyngeal
apparatus elongated, with a flexible pharyngeal tube, two long and thin macroplacoids,
and a comma-shaped microplacoid. Drop-like thickening between the buccal
and the pharyngeal tube, and the pharyngeal apophyses, absent. Pharyngeal tube with
double annulation – that is, closely arranged pairs of rings separated by spaces without
annulation (visible with SEM only, under PCM the annulation appears single). Claws of
the Hypsibius type – that is, asymmetrical both with respect to the sequence of primary
and secondary branches (2–1-2–1) and with respect to the size, with external and
posterior claws being always clearly larger than internal and anterior claws. Basal
claws and secondary branches form a hooked curve. Primary branches with accessory
points. Eggs smooth, deposited in exuviae (oviposition synchronised with moulting).

M. spitzbergensis diagnosis:Body elongated, cylindrical, yellowish, covered with smooth cuticle – that is, without pores or granulation (Figure 1). Cribriform areas unidentifiable under PCM. Eyes absent in live animals.Bucco-pharyngeal apparatus of the Mesocrista type, elongated (Figure 2(a–b)). Oral cavity armature visible both under PCM (Figure 2(a), arrowhead) and under SEM (Figure 2(c)), composed of the second and the third band of small teeth in the posterior of the oral cavity (the first band of teeth in the anterior of the cavity is absent). In PCM, the teeth of both bands appear as single rows of densely arranged dots, with the dots of the second band being clearly smaller than those of the third band (Figure 2(a), arrowhead). SEM shows that the second band of teeth is composed of 5–6 irregular rows of small- and medium-sized conical teeth, whereas the third band of teeth comprises a single row of large conical teeth (Figure 2(c)). Two distinct porous areas on the lateral sides of the buccal crown (visible in SEM only). Furcae robust, triangular, with swollen and rounded apices (Figure 2(b)). Macroplacoid length sequence 1 < 2, with the second macroplacoid being more than twice as long as the first macroplacoid. Second macroplacoid slightly broadened and rounded in the posterior part and with a slight subterminal constriction (Figure 2(b)). Although under PCM the annulation of the pharyngeal tube appears single, it is clearly double under SEM (compare Figure 2(a and b)). Double annulation regular, only occasionally a ring from an adjacent pair joins with the closest ring of the neighbouring pair to form a triple ring (Figure 2(d)). Claws of the Hypsibius type, very slender, with slightly widened bases and with pronounced accessory points on the primary branches (Figure 3). The posterior primary branches are clearly longer than the external primary branches I–III. Three cuticular bars/thickenings on legs I–III present. The most distal bar is placed transversally between claw bases, and it is usually very short, roundish, almost dot-like (Figure 3(a), arrowhead). The second bar runs along the proximal side of the internal claw and is in the shape of a thin crescent with fuzzy margins (Figure 3(a), filled arrow). The most proximal bar is a mirror image of the second bar, is placed at a distance of 5–8 μm and is the faintest of the three bars (Figure 3(a), empty arrow). On the hind legs, a single transverse bar between the anterior and posterior claw is present, always clearly separated from the basal portion of the posterior claw (Figure 3(b), arrowhead).
-Gasiorek et al. 2016
Body Length: 399-548 microns.
Key Characters: Yellowish body in live specimens, two bands of teeth in oral cavity armature, slender claws. Differs from M. revelata by several other morphometric traits.
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: Soil and tree moss.
Abundance: Very rare. This species makes up 0.07% of terrestrial specimens collected in the Great Smoky Mountains National Park in Bartels' inventory.
Diet: Microbivore.
Reproduction: Smooth eggs deposited in exuvium.
Observation Methods: DIC and PC.
Wikipedia

 Photo Gallery for Mesocrista spitzbergensis - No common name

Photos: 10

Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Habitus, DIC		Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Anterior, DIC
Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Anterior, PC		Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Buccal apparatus, PC
Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Claws I and II, PC		Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Claws IV
Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Lateral, PC		Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Lateral, DIC
Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Buccal apparatus, PC		Recorded by: Bartels on 2002-11-23
Haywood Co.
Comment: Buccal apparatus, PC