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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Stephensoniana

Stephensoniana Cernosvitov, 1938 (ref. ID; 6913, 6972)

Family Naididae (ref. ID; 5939)

Family Naididae: Subfamily Naidinae (ref. ID; 6648)
  1. Stephensoniana tandyi (ref. ID; 5939)
  2. Stephensoniana trivandrana (Aiyer, 1926) (ref. ID; 6648, 6913, 6972) reported year? (ref. ID; 5883)

Stephensoniana trivandrana (Aiyer, 1926) (ref. ID; 6648, 6913, 6972) reported year? (ref. ID; 5883)

Descriptions

Lake Biwa material: Body 2.0-2.5 mm long, 0.18 mm wide in fixed state. Segments of an intact an immature specimen 32. No eyes. Foreign matter adhering to body wall, concentrated in middle part of each segment. Prostomium conical. Dorsal chaetal bundles beginning in II, consisting of finely hispid hairs, and needles without nodulus and tapering distally with simple pointed end. Dorsal hairs 2-4 per bundle anteriorly, 1-2 per bundle posteriorly, 120-160 µm long. Dorsal needles 3-4 per bundle anteriorly, 2-3 per bundle posteriorly, 40-60 µm long. Ventral chaetae bifurcate with nodulus proximally; those in anterior segments 1-3 per bundle, upper tooth about twice longer and as thick as lower, those in posterior segments 1-2 per bundle, the length hardly changing but upper tooth becoming much (more than three times) longer than lower. Stomach suddenly widening in VI. (ref. ID; 6648)

Dorsal chaetae beginning in II, with up to 5 hairs and 5 simple-pointed needles (mostly 2 or 3 of each). Ventrals 4 per bundle, upper teeth becoming progressively longer in more posterior segments. (ref. ID; 6972)

Remarks

Newly recorded for Lake Biwa. The dorsal hairs of Lake Biwa specimens are invariably hispid. Such hispid hairs were also confirmed in other Japanese specimens from Lake Kitaura, although they have not been described before. Other characteristics examined in Japanese material agree well with those in the previous descriptions. (ref. ID; 6648)

The chaetae in this species are quite characteristic. It has already been recorded from China. (ref. ID; 6972)

Material examined

Four immature individuals, off Ayame-hama (the northern lake), 10 m depth, mud, 30th June, 1990, 31st July, 1991. One immature individual, center of the southern lake, 4.3 m depth, mud, 24th February, 1995. One immature individual, off Shimosakamoto (the southern lake), 3 m depth, muddy sand with submerged vegetation, 2nd August, 1995. Two immature individuals, center of Lake Kitaura, 6 m depth, mud, 3rd August, 1983, 20th January, 1984. (ref. ID; 6648)

1 specimen, Zhujiang River, Huang-zhu-qi, Guangzhou, Guangdong Province, 1985. Qi Sang collection. (ref. ID; 6972)