Gieysztoria rubra ( Fuhrmann, 1894 ) Ruebush & Hayes, 1939

Steenkiste, Niels Van, Gobert, Stefan, Davison, Paul, Kolasa, Jurek & Artois, Tom, 2011, Freshwater Dalyelliidae from the Nearctic (Platyhelminthes, Rhabdocoela): new taxa and records from Ontario, Canada and Michigan and Alabama, USA, Zootaxa 3091, pp. 1-32 : 17-19

Gieysztoria rubra ( Fuhrmann, 1894) Ruebush & Hayes, 1939

( Figs. 6 A–C)

syn. Vo rt e x r u be r Fuhrmann, 1894

syn. Dalyellia rubra ( Fuhrmann, 1894) Graff, 1904

syn. Microdalyellia rubra ( Fuhrmann, 1894) Gieysztor, 1939

syn. Microdalyellia (Gieysztoria) rubra ( Fuhrmann, 1894) Ruebush & Hayes, 1939 syn. Microdalyellia (Gieysztoria) ornata ( Hofsten, 1907) Marcus, 1946 (uncertain)

New locality. Blackwell Run, Madison County, Alabama, USA (34°33’51”N, 86°46’43”W). Swamp with Ceratophyllum demersum and Utricularia macrorhiza (23/05/2009).

Known distribution. Widespread throughout the Western Palearctic: many localities in Europe, Western Russia, Siberia (see Luther 1955 for localities and references), Western Europe ( UK: North West England, West Midlands and North Wales) ( Young 1970), Central Europe ( Germany: Schleswig–Holstein, Thuringia, Franconia, South Lower Saxony) ( Rixen 1961; Pörner 1966; Kaiser 1967; Bauchhenss 1971; Heitkamp 1981, 1982), Southern Europe ( Spain: Castilla–La Mancha, Extremadura) ( Gamo & Mayor 1987; Noreña et al. 1999), Western Russia (Urals, upper Volga River) ( Rogozin 1996; Korgina 2002) and Siberia ( Rogozin 1996); Afrotropic: western Great Rift Valley ( DR Congo: Lake Edward) (Marcus & du Bois-Reymond Marcus 1957) and East Africa ( Kenya: Nairobi, Eastern Province and Rift Valley Province) ( Young 1977); Neotropic: Brazil? (São Paulo) ( Marcus 1946; uncertain, see below).

Material. Observations of two live animals, one of which was subsequently whole-mounted.

Description and remarks. Large species of Gieysztoria with a length of about 1.8 mm, with eyes and having a brown to bright orange–red pigmentation throughout the whole body ( Fig. 6 A). The pharynx dolliiformis (ph) is up to 1/4 of the body length long. General organisation of the genital system does not, as far as could be observed, differ from the normal situation within Gieysztoria ( Fig. 6 B) (see Luther 1955).

The 62 µm-long stylet (st) is relatively small and consists of a 25 µm-long girdle composed of a proximal and distal ring interconnected by a large number of bridges ( Fig. 6 C). The distal ring bears at least 20 homoiomorphic spines of a similar length (43 µm) with an elongated base and slightly outwards pointing distal ends. The precise number of spines is difficult to count because of the positioning of the stylet in the whole mount.

Vitellaria (vi) have long, digitiform papillae and run dorsolaterally from the intestine. A long, bent ovary (ov) lies behind the intestine on the left hand side of the body, with adjacent to it the seminal receptacle (rs) ( Fig. 6 B). The latter is a short-stalked vesicle which is clearly separated from the rest of the female system. In one specimen, the seminal receptacle contained different compartments with sperm in varying degrees of decomposition. This partitioning and gradual breakdown has also been observed in other populations (see Luther 1955). Caudally, the uterus contains an oviform to triangular egg (e) ( Fig. 6 B).

The specimens from Alabama are relatively large compared to the normal size range known for this species (1– 1.6 mm, see Luther 1955). Only considering stylet morphology, G. rubra ( Fuhrmann, 1894) Ruebush & Hayes, 1939 is identical to G. o r n a t a ( Hofsten, 1907) Ruebush & Hayes, 1939. The stylet of G. r u b r a is also very similar to that of G. expeditoides Luther, 1955 and G. expedita ( Hofsten, 1907) Ruebush & Hayes, 1939 , but the girdle of these species is not fenestrated. The most important difference between G. rubra and G. ornata is the presence of large papillae in the vitellaria of G. rubra . In contrast, the vitellaria of G. ornata are smooth or only slightly papillose. However, the taxonomic importance of this diagnostic feature has been debated. Marcus (1946) described his specimens from Brazil as G. o r n a t a, but they were later transfered to G. r u b r a by Luther (1955) because of their papillose vitellaria. This was questioned by Brusa et al. (2003) who dispute the taxonomic importance of the shape of the vitellaria because of its variable appearance depending on the state of development of the animal. Consequently, they reassigned the Brazilian specimens to G. ornata based on the shape and structure of the stylet spines.

A stalked, separate seminal receptacle is also present in G. expeditoides , G. cuspidata ( Schmidt, 1861) Ruebush & Hayes, 1939 , G. b e rg i ( Beklemischew, 1927) Ruebush & Hayes, 1939 and G. maritima Luther, 1955 , but these species differ from G. r u b r a in stylet morphology or the habitus of the vitellaria (see Luther 1955). Its variable morphology, widespread distribution and the recognition of several subtaxa [ G. rubra caucasica ( Nasonov, 1919) Ruebush & Hayes, 1939 , G. rubra frankia ( Nasonov, 1919) Ruebush & Hayes, 1939 , G. rubra typica ( Gieysztor, 1931) Ruebush & Hayes, 1939 and G. rubra intermedia ( Gieysztor, 1931) Ruebush & Hayes, 1939 ] are strong indications that G. rubra represents a species complex, possibly including G. o r n a t a (see Luther 1955). This is likely also the case for many other taxa within Microdalyellia [e.g. M. rossi ( Graff, 1911) Gieysztor, 1938 , see further] and Gieysztoria .

Based on the above-mentioned features, provisionally including the papillae of the vitellaria, the specimens from Alabama are placed in G. rubra . As so, this is the first record of this species for the Nearctic.

Figures

FIGURE 6. Gieysztoria rubra (Fuhrmann, 1894) Ruebush & Hayes, 1939 (A) Squeezed live animal, dorsal view. (B) Detail of the genital system in a live animal. (C) Stylet. Gieysztoria dodgei (Graff, 1911) Ruebush & Hayes, 1939 (D – F) Stylets.