Description:-

Worms have an indefinite light yellowish hue and is fairly transparent under the microscope. When placed in a petri dish containing water, they crawl freely on the bottom. Formalin preserved specimens with a single budding zone measured 1.5-2.0 mm in length and have 25-30 segments, segmentation being well marked. Prostomium short and rounded; the surface epithelium is thicker at its tip than elsewhere in the body. Mouth transverse reaching from side to side. Eyes are placed at the base of the prostomium. They are irregularly ovoid in shape and formed by aggregation of black pigments with a violet tinge. Additional smaller eyes are present (Nebenangens). In one worm five such spots have been counted all placed dorsally. Body is cylindrical uniformly decreasing in diameter toward the posterior region. Anus at the terminal region. Ventral bundle begins from the II segment with a constant number of three setae per bundle. Anterior bundles (II, III, IV and V) have slightly proximal nodulus, VI with median nodulus and posterior with distally placed nodulus for their setae. In the anterior II-V segments, the distal prong is thinner and longer than the proximal. But by the VI segment they are of equal length and width. Setae of II and III segments are comparatively longer (125.0µ), IV and V (100.5µ), VI-XI (90.0µ) and this is followed by setae of 87.5µ in the succeeding segments. Dorsal bundle commencing from the second segment with only one hair seta and one needle seta per bundle. Hair setae smooth without any ornamentation, length varying from segment to segment. They arise from lobulated setal sacs. In some they have fallen out and in some others they have obviously been broken off. Needles bifid, the two prongs being rather very small. The nodulus is indistinct and a sharp bent occurs at the distal region. Buccal cavity occupies the II segment. Pharynx commences from the anterior septum of the III segment and extends up to ¾ of the IV segment. This is followed by the oesophageal region till the VII segment where it is continued as the stomach. Asexual reproduction was noticed in six individuals; ‘n’ being XVI twice, XVII thrice and XVIII only once.

Threats:-

Not recorded

Remark:-

Habitat:-

Planktonic forms and also attached to the ‘roots’of Salvinia molesta.

Synonyms:-

Nais elinguis Muller, 1773
Nais heterochaeta Benham, 1893
Nais communis Piguet, 1906
Nais parviseta Walton, 1906
Nais communis Piguet. Piguet, 1913
Nais variabilis var. panjabensis Stephenson, 1909
Nais communis var.punjabensis (Stephenson). Piguet, 1909
Nais communis var. caeca Stephenson, 1910
Peterochaeta astronensis Pierantoni, 1911
Nais communis var. caeca Stephenson. Stephenson, 1914

References:-

Sobhana, S. 1982. Studies on the biology of the aquatic oligochaetes of Kerala. Ph.D Thesis submitted to University of Kerala. Dep.t of Aquatic biology and Fisheries.