Echiniscus spiniger Richters, 1904

Gąsiorek, Piotr & Degma, Peter, 2018, Three Echiniscidae species (Tardigrada: Heterotardigrada) new to the Polish fauna, with the description of a new gonochoristic Bryodelphax Thulin, 1928, Zootaxa 4410 (1), pp. 77-96: 89-91

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Echiniscus spiniger Richters, 1904


Echiniscus spiniger Richters, 1904  

( Fig. 34 View FIGURES 30–35 )

Locus typicus. Visby, Gotland, Sweden.  

Material examined. Three adult specimens and one juvenile, found together with exceptionally abundant Echiniscus granulatus   , E. testudo ( Doyère, 1840)   , and Richtersius coronifer   (PL.247; Kościeliska Valley.

Description. Medium-sized (160–313 µm), dark-yellow. Cirrus A long (104 µm, cirrus A/ body length ratio 33%). Cirrus internus / externus length ratio 60–65%. Plate sculpture composed of small and medium-sized pores ( spinulosus   type), with the largest pores found on the large median plates and on the caudal plate. Lateral and dorsal appendages at B, C, C d, D, D d, and E in the shape of long spines, with dorsal spines slightly longer than the lateral ones (38–48 µm vs 21–36 µm). Pedal (leg) plates very well-developed and large, those on leg IV forming a collar composed of eight small, blunt teeth. Claws I –III moderately shorter than claws IV (12.5–20.6 µm, 27.3– 31.1% vs 16.9–23.6 µm, 30.3–38.3%). Spurs (1.5–3.9 µm, 3.4–5.8%) positioned at ~30% of the claw length.

Remarks. New record for Poland. Dastych (1988) expressed the opinion that the so-called spinulosus   - quadrispinosus   group was in need of a complete revision, and produced a schematic illustration of E. spinulosus ( Doyère, 1840)   with long lateral appendages. He also remarked that the lateral appendages of Polish E. spinulosus   specimens varied significantly in length ( Dastych 1988). Presented findings suggest that his records could embrace two distinct species: E. spinulosus   s. s., which is a predominantly lowland species, and E. spiniger   , more frequently found in colder and upland habitats. In E. spinulosus   specimens from the locus typicus (Saint-Maur-des-Fossés, France), dorsal spines C d and D d are longer than the extremely short lateral spines (similar to the differences in length recorded for E. scabrospinosus Fontoura, 1982   , see Figs 31–32 View FIGURES 30–35 ). In E. spiniger   , the lateral spines are longer and of similar or equal development to the dorsal appendages ( Fig. 34 View FIGURES 30–35 ).

Scottish specimens of E. quadrispinosus Richters, 1902   of identical body size to Polish E. spiniger   specimens have dorsal spines C d and D d distinctly shorter than in E. spiniger   , and unlike in E. spiniger   , spines D d are typically shorter than C d ( Fig. 35 View FIGURES 30–35 ). Moreover, all lateral appendages in E. quadrispinosus   are developed as long cirri with broad bases ( Ramazzotti & Maucci 1983).

Pilato et al. (2008) showed that different species within spinulosus   group can be separated on the basis of differences in plate sculpturing. An interesting pattern can be observed within members of the group: generally, species with short appendages exhibit large and sparsely distributed cuticular pores, whereas those with long spines or cirri possess comparatively smaller, more densely arranged pores (compare Figs 31–32 View FIGURES 30–35 for E. spinulosus   and E. scabrospinosus   , and 33–35 for E. lichenorum Maucci, 1983   , E. spiniger   and E. quadrispinosus   ). Curiously, E. migiurtinus Franceschi, 1957   with reduced set of trunk appendages (exclusively stout spines D d present) seems to deviate from this rule, since it exhibits small, densely arranged pores ( Fig. 30 View FIGURES 30–35 ). However, there are also differences in the degree of pedal (leg) plate development between the representatives of the spinulosus   group. Such differences could be a stable specific trait. Pedal (leg) plates can be: invisible in PCM on all legs ( Fig. 32 View FIGURES 30–35 ); visible only on legs IV ( Figs 30, 33, 35 View FIGURES 30–35 , arrowheads); or present on all legs, and with strongly developed sculpture similar to that on the dorsal plates, which so far was detected only in E. spinulosus   and E. spiniger   ( Figs 31, 34 View FIGURES 30–35 , arrowheads). It is clear that additional studies are needed to better understand the phylogeny and evolution of morphological traits within this species complex. For the Polish fauna, both E. spiniger   and E. spinulosus   should be considered as its indigenous components.

The presence of E. testudo   , a typical lowland species, within this sample, represents the first record for this species from the Polish Tatras ( Dastych 1980).


Polish Collection of Microorganisms