Archivortex silvestris Reisinger, 1924

Houben, Albrecht M., Schwank, Peter, Proesmans, Willem, Bert, Wim & Artois, Tom J., 2015, Notes on some enigmatic taxa of limnoterrestrial rhabdocoels, with the description of two new species, Zootaxa 4040 (1), pp. 83-92 : 90-91

Archivortex silvestris Reisinger, 1924

( Figs. 1 D–E)

New localities. Kanzelkügel, Graz, Austria (47°06’49”N; 15°23’11”E), nine specimens in moist forest soil (26 August 2011).

Kreuzberg, Weyer, Austria (47°51’36”N; 14°39’09”E), one specimen in humus of mixed forest (29 August 2011).

Known distribution. In the vicinity of Graz, Austria. Common and abundant in humus of forest soils ( Reisinger 1924); Pendling bei Kufstein, Austria (An der Lan 1963).

Material. Ten specimens studied alive, three of which were sagitally sectioned (UH nos. VI.4.13–VI.4.15).

Descriptive notes and remarks. This species was originally described by Reisinger (1924) and was only later illustrated by Bresslau (1933: fig. 259) and Reisinger (1954: fig 6). The study of our specimens revealed some more morphological details.

Animals about 0.2 mm long. The anterior end with glands ( Fig. 1 E: frg), particularly obvious in live animals.

Rhabdites are lacking, but the outer part of the epidermis is completely covered with small structures that were originally described as pseudorhabdites ( Reisinger 1924). Paired protonephridiopores ( Fig. 1 E: pp) open just behind the pharynx doliiformis ( Fig. 1 D, 1E: ph), which is situated in the anterior 20 % of the body.

The gonopore is situated at ±75 % and opens into a small genital atrium.

Paired, round testes ( Fig. 1 E: t) lie at ±65 % of the body. An inner circular and an outer longitudinal muscle layer surround the 13 µm-long copulatory organ ( Fig. 1 E: co). This copulatory organ contains a seminal vesicle, a prostate vesicle and a slightly-bent, somewhat sclerotized ejaculatory duct. The prostate vesicle is filled with eosinophilic secretion, although the glands producing this secretion were not observed.

The female system is very simple. A single vitellarium ( Fig. 1 E: vi) embeds the ovary ( Fig. 1 E: ov) forming an ovo-vitellarium, which is connected to the genital atrium by a female duct.

We refrain from designating a neotype because the sectioned specimens are of too poor quality.