Bdellocephala annandalei
Chromosome number: 2x = 28 and n = 14.
Karyotype: 2m + 2sm + 2sm + 2sm + 2sm + 2m + 2m + 2m + 2m + 2m + 2m + 2m + 2m + 2m.
Bdellocephala annandalei has a whole-body light brown color, ventral surface is paler compared with the dorsal one. The margins of the body and the areas above to the pharynx and the copulatory apparatus are lighter.
Like the other dendrocoelids, B. annandalei, has a subterminal adhesive organ on the ventral side of the frontal end. This reniform organ is folded longitudinally and is covered with glandular epithelium.
The head presents two small eyes at the middle and two elongated auricules on each side. Behind these auricules the body becames narrower, and then it widens at the level of the pharynx and the copulatory apparatus.
This is a comparatively large species. Sexually mature individuals are over 35-40 mm in length and 10-12 in width.
This species is endemic of the Lake Biwa-ko in the central part of Honshû, in Central Japan. Biwa-ko is the largest and oldest lake in the country.
Bdellocephala annandalei lives in the northern basin of the Lake Biwa-ko, at 20-103 meters in depth. It's found on the muddy bottom of the lake.