Testudinella elliptica (Ehrenberg, 1834)

De, Willem H., 2009, A review of the marine and brackish-water species of Testudinella (Rotifera: Monogononta, Testudinellidae), with the description of two new species, Zootaxa 2092, pp. 1-20 : 13-14

publication ID

https://doi.org/ 10.5281/zenodo.187516

DOI

https://doi.org/10.5281/zenodo.6215593

persistent identifier

https://treatment.plazi.org/id/953D87D5-FFC6-FF92-FF3B-EBF7AB1AFF71

treatment provided by

Plazi

scientific name

Testudinella elliptica (Ehrenberg, 1834)
status

 

Testudinella elliptica (Ehrenberg, 1834) View in CoL

( Figs 11 View FIGURE 11 & 12 View FIGURE 12 )

Synonym: T. pseudoclypeata Bērziņš, 1943 , T. clypeata f. pseudoclypeata after Koste (1978)

non T. elliptica View in CoL after Bartoš (1951, Figs 7 View FIGURE 7 , 8 View FIGURE 8 ) and Jersabek et al. (2003, ANSP Catalog Number 1828) Testudinella elliptica View in CoL has often been confounded with T. clypeata View in CoL , due to the rather similar lorica outline and shape. The antero-dorsal margin is convex, the antero-ventral one shows a broad V-shaped sinus; the two antero-ventral lobes are finely granulated. Ratio lorica length/lorica width 1.40–1.65 (average 1.53). The most characteristic features distinguishing T. elliptica View in CoL from T. clypeata View in CoL are its large, more or less semi-lunar ventral foot opening situated close to the posterior edge ( Fig. 11 View FIGURE 11 A–C), the massive distal ( Fig. 11 View FIGURE 11 E) and short penultimate foot pseudosegment, and the more anteriorly placed dorsal and lateral antennae, with the ratio lorica length/position of antenna(e) relative to dorsal anterior margin varying between 3.00–3.40 (average 3.16) and 3.30–3.60 (average 3.43) respectively. The lorica is usually also slightly, more or less abruptly narrowing anteriorly at the height of the lateral antennae. In cross-sectional view ( Fig. 11 View FIGURE 11 D) the dorsal margin appears convex, the lateral edges are broadly rounded continuing more or less strongly flattened ventrally, and becoming separated from a more or less convex median part by shallow sulci. Two red eyespots.

The trophi ( Fig. 12 View FIGURE 12 , and De Smet (2005)) have 16–17/16–17 (left/right) uncinal teeth, with very slender and only weakly offset heads, bearing two small lateral knobs at their base. The manubria consist of three large superimposed chambers and a strongly reduced sub-ventral chamber. The number of arched rami scleropili is ~50/46–66 (left/right). The fulcrum lacks a proximal opening frontally.

Measurements. Lorica length 170–250 µm, lorica width 105–205 µm, distal foot pseudosegment 36–40 µm.

Testudinella elliptica View in CoL is a widespread species reported from the Palaearctic, Nearctic, Oriental and Neotropical regions ( De Ridder & Segers 1997). It is primarily an inhabitant of fresh waters, living among submerged vegetation and in benthos, or as epibiont on Asellus aquaticus (Linnaeus, 1758) View in CoL (Crustacea, Isopoda View in CoL ). The reports from marine and brackish habitats (see also Fontaneto et al. (2006)) have to be interpreted with caution and may concern occasional introductions or confusions with T. clypeata View in CoL . In this respect it is interesting to mention that in culture experiments with T. elliptica View in CoL , de Beauchamp (1928) observed that specimens died at a 0.2 % salt concentration, and he wonders claiming that ‘the species is euryhaline and living also in brackish waters’.

Bērziņš (1943) described T. pseudoclypeata View in CoL from a freshwater pond in Lettland, and considered the species closely related to T. clypeata View in CoL . According to Segers (2007) T. pseudoclypeata View in CoL is a synonym of T. clypeata View in CoL , occasionally considered an infrasubspecific variant of the latter. Bērziņš (1943) considered the transverse-oval foot opening and flattened shape of the ventro-lateral and medio-ventral margins as characters distinguishing it from T. clypeata View in CoL . However, a large transversal foot opening, flattened ventro-lateral margins, as well as the ratio lorica length/position lateral antennae = 3.6 (which can be derived from Bērziņš’ Fig. 25) are typical for T. elliptica View in CoL . The degree of flattening of the median ventral part largely depends on the state of development of the vitellarium. Consequently there are no characters differentiating between T. pseudoelliptica View in CoL and T. elliptica View in CoL , and it is concluded that the two names are synonyms.

Kingdom

Animalia

Phylum

Rotifera

Class

Eurotatoria

Order

Flosculariaceae

Family

Testudinellidae

Genus

Testudinella

Loc

Testudinella elliptica (Ehrenberg, 1834)

De, Willem H. 2009
2009
Loc

Asellus aquaticus

Linnaeus 1758
1758
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