Tardigrades of North Carolina
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View PDFStygarctidae Members: 2 NC Records

Stygarctus bradypus Schulz, 1951 - No Common Name


Dorsal and ventral drawing, based on specimens from Germany, Ramazzotti & Maucci 1983
Taxonomy
Class: HeterotardigradaOrder: "Arthrotardigrades" Family: StygarctidaeSubfamily: Stygarctinae Checklist Number: 2280.0
Taxonomic Comments: There are currently (October 2023) eight species in this genus.
Species Notes: Marine. S. bradypus is very similar to Stygarctus n. sp. It is impossible to know to which species these records belong. S. bradypus proper has been reported broadly from Asia, Europe, N and S America. In the US it has been reported along both east and west coasts.
Identification
Online resources:Online Photographs: Google, GBIF                                                                                 
Species Description: Stygarctus bradypus proper:
The body appears clearly segmented into 5 parts: a cephalic region (plate) well delimited, three unpaired dorsal plates, which also encompass the body laterally as far as to cover the bases of the legs, and a terminal plate, not curved at the sides and without notch or incision. At first examination the appearance calls to mind the Echiniscidae, however the type of armor is fundamentally different and the plates do not have sculpture. The cephalic appendices are: short median (unpaired) cirrus inserted perpendicularly, with it on thick base, in a hollow of the cephalic plate and considerably distant from the anterior margin of it; lateral cirrus (paired) and clava (unpaired), the latter visibly club-shaped, separate from the lateral cirrus, which arises from a thick base; internal, or medial, (paired) and external buccal cirri (paired), also with bases; cephalic papilla (paired) by the side of the buccal aperture, large, composed of a short basal part which continues, after a bend, with a terminal piece larger and longer, narrowly adherent to the external cephalic margin and turned laterally. These cephalic papillae, of unusual shape in tardigrades, gives the impression of palps and may easily escape -- by their position -- a hasty examination. The cephalic appendices are better seen observing the tardigrade frontally (Fig. 619, e, anterior part). There exists then, at the posterior margin of the cephalic plate and of the three unpaired plates, appendices which -- observed dorsally -- have the appearance of teeth or hooks turned toward the caudal end: it consists of a refringent lamella, which continues as a lamella still more delicate and transparent, visible only with strong magnification and with the diaphragm very closed. From the posterior margin of the second unpaired dorsal plate, near the median line of the animal, departs two spines 23-25~ long,turned transversely toward the lateral margin which they approximately reach. The terminal plate bears two caudal appendices, in the form of spines, whose length is almost equal to three-fourths of that of the legs of the 4th pair. The buccal aperture is circular and subterminal, positioned on a buccal cone, which may be retracted or bent (Fig. 619, e): it continues with the buccal tube, about 40~ long, which enters for a short distance into the spherical or oval pharynx (diameter S-lop), forming then the pharyngeal bars (Fig. 619, c), whose structure, somewhat different than usual, may not be totally clear. The stylets are straight, or weakly curved, and it seems that the stylet supports are absent. The legs have the median part telescopically retractile into the proximal and has distinct mobility in various directions: they may also be folded on the dorsum; the legs of the 4th pair are very long. Claws without spurs, straight for three-fourths of their length and only distally curved: on the two internal claws of all the legs exists a pliable bristle, at least as long as the entire claw and inserted on the claw, at the end of the straight part and at the beginning of the curvature; the author named this bristle “Tasthaare” [tactile hair], specifying however that it is not intended to refer to their function, of which we know nothing, but only use a convenient expression.
-Ramazzotti & Maucci 1983.
Body Length: 90-150 microns.
Key Characters: Dorsal spines present at posterior margin of second unpaired dorsal plate, comb-like processes on funnel-shaped lateral expansions absent, buccal tube long (Sl/BTL ratio approx 50%).
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: Intertidal beach sand.
Abundance: Unknown.
Diet: Herbivore.
Reproduction: Sexual reproduction, females with spermatheca, probably smooth eggs deposited in exuvium.
Observation Methods: PC.
Wikipedia

 Photo Gallery for Stygarctus bradypus - No common name

Photos: 1

Recorded by: Lindgren on 1970-03-10
Carteret Co.
Comment: Dorsal and ventral drawing, based on specimens from Germany, Ramazzotti & Maucci 1983