Krumbachia hiemalis Schwank, 1979

Diez, Yander L. & Schmidt-Rhaesa, Andreas, 2024, Little neighbours in Hamburg: free-living aquatic flatworms (Platyhelminthes), Evolutionary Systematics 8 (2), pp. 279-310 : 279-310

Krumbachia hiemalis Schwank, 1979

Fig. 12

Known distribution.

Until now, this species was only known from its type locality in Schlitz, Hessen, Germany ( Schwank 1979).

Material.

Sixteen specimens studied alive, five of them whole mounted ( ZMH V 13843 –13847), nine preserved for future histological, and two used for molecular studies. Animals collected in Wittenberg, Rissen, on tree holes filled with water and litter, 20–50 cm over the ground level.

Description.

Live animals 1.5–2 mm long, unpigmented and without eyes (Fig. 12 A ). Strong adhenal rhabdite tracts (Fig. 12 B : ar) open in the anterior body end. Body oval-elongated, with the anterior margin broader than the posterior. The pharynx (Fig. 12 A, C : ph) is located about midbody, 285 µm in diameter (all provided measures of this species are based on a single living specimen).

The testes (Fig. 12 A : t) are located anterior and the ovary and atrial organs posterior to the pharynx. The male copulatory organ (Fig. 12 A, C : mco) is 156 µm long and encompasses a seminal vesicle, a prostate vesicle, the sclerotised ejaculatory duct, and a bundle of accessory glands. The seminal vesicle (Fig. 12 D, E : sv) receives independently both spermatic ducts and, then, opens into the prostate vesicle. The prostate vesicle (Fig. 12 D, E : pv) contains a granular secretion, also observable throughout the ejaculatory duct. The ejaculatory duct (Fig. 12 D, E : ed) is 102 µm long, with slightly sclerotised walls (not observable on the whole mounts). The distal half of the male copualatory bulb is occupied by a mass of accessory glands (Fig. 12 D, E : gl), surrounding the ejaculatory duct.

The vitellaria (Fig. 12 A : vi) extend at the body sides, between the brain and the posterior part of the body. The ovary (Fig. 12 A, C : ov) is 152 µm long, with the oocytes increasing in diameter from proximal to distal. The female duct connects the ovary to the female atrium. A seminal reservoir (Fig. 12 A : sr) opens into the female duct (no sperm observed in this structure). The bursa (Fig. 12 A, C – E : b) opens into the common general atrium in between the apertures of the female and male atria. Several vesicles were observed within the bursa but no sperm.

The morphology of the specimens collected in Hamburg closely aligns with the description outlined by Schwank (1979). For specimens from the type locality, the copulatory bulb length falls within the range of 120–180 µm. Additionally, Schwank (1979) noted the proximal oblique opening of the sclerotized duct in this species, a characteristic clearly observable in our recently collected specimens. This species stands out from all others within the genus Krumbachia due to the distinctive combination of a two-layered cuticularised ejaculatory duct, notable for its high mobility, and a bursa characterised by a remarkably thin wall.

Figures

Figure 12. Krumbachia hiemalis. A. Habitus of live specimens; B. Anterior region; C. Posterior region; D, E. Atrial organs. Scale bars: 50 μm (B – E).