Aquatic oligochaeta is one of the most abundant and ecologically important groups in freshwater benthic environments (Jung, 2011). Most species in this group are < 1mm to a few centimeters in length. This group contains several families. Among them, naidid worms are small benthic and/or epibenthic oligochaetes with a worldwide distribution. About 180 species of naidid oligochaetes have been described(Erséus, 2005) and 24 genera are currently recognized(Envall et al., 2006).
The species diversity of this family has been the subject of considerable investigation in China, Japan, and Korea. Fiftyeight and 30 species have been reported in China and Japan, respectively(Timm, 1999; Wang and Cui, 2007). In recent years, 15 naidid species in 11 genera have been added to the Korean aquatic oligochaete fauna (Jung, 2011, 2012; Park, 2013). Of these, one species in the genus
The specimens were collected with a plankton hand net (mesh size 100μm) from the roots of waterweeds at the edge of streams covered with sand or organic matter. The samples werekept cooland were sorted in the laboratory using a stereomicroscope while the worms were alive. Then, the samples were preserved in 70% ethanol solution. The specimens were stained with Rose Bengal dye for observations and measurements and were temporarily mounted in glycerin. Pictures were taken with a BX41 optical microscope(Olympus,Tokyo, Japan) and an EOS 650D camera(Canon, Tokyo, Japan). The figures are drawn using a microscope equipped with a drawing tube. Measurements were taken using a micrometer on the microscope. These mounted collections are being kept in the lab of Ecology Genetic(LEG), Department of Science Education, Ewha Womans University. Other material, preserved in 70% ethanol solution, was submitted to the National Institute of Biological Resources(NIBR) of the Republic of Korea.
Order Haplotaxida Family Naididae Ehrenberg, 1828 Genus Dero Oken, 1815
[Fig. 1.] Dero dorsalis Ferroniere, 1899. A, Dorsal chaetal bundle of IV (length of bifid chaeta 30.43μm, length of hair chaeta 90.92 μm); B, Ventral chaeta of IV (length 36.37 μm); C, Branchial fossa and posterior gills, dorsal aspect. Scale bars: A, C= =10 μm, B=5 μm.
Xantho decaopada Dutrochet, 1819: 155. Nais decapoda(Dutrochet). Blainville, 1825: 131. Uronais decapoda(Dutrochet). Gervais, 1838: 18. Dero decapoda(Dutrochet). Vaillant, 1890: 386. Dero darsale Ferronière, 1899: 255. Dero tubicola Pointner, 1911: 274, Pl. XXVIII, figs. 4, 5; Schuster, 1915: 18, figs. 10-14; Malevich, 1929: 47; Ude, 1929: 36, fig. 41. Dero austrina Stephenson, 1925: 882, Pl. I, fig. 1; Aiyer, 1929: 34, figs. 10, 11; Stephenson, 1931: 269; Michaelsen, 1933: 334; Chen, 1940: 57, figs. 18, 19. Dero dorsalis Ferronière, Michaelsen, 1933: 334; Sperber, 1948: 162; 1950: 70, figs. 22, 23a; Cekanovskaya, 1962: 171, fig. 90; Naidu, 1962: 529, fig. 12a-h.
[Fig. 3.] Allonais pectinata (Stephenson, 1910). A, Dorsal pectinate chaetae of III (length 2.52 μm [left], 2.62 μm [right]); B, Dorsal chaeta of IV (length 3.30 μm); C, Dorsal chaetae of VI (length 3.91 μm [left], 3.37 μm [middle]); D, Ventral chaeta of III (length 5.93μm). Scale bars: A-D=1μm.
Nais pectinata Stephenson, 1910: 236, Pl. XI, fig. 1a-f; 1920: 198; 1923: 63, fig. 19a-f; 1932: 229, fig. 1a, b; Aiyer, 1929: 19, fig. 2a-d. (non) Nais pectinata Stephenson. Stephenson, 1931: 302. Nais denticulata Chen, 1940: 39, fig. 8A-E. Allonais pectinata(Stephenson). Sperber, 1948: 206; Naidu, 1962: 915; Brinkhurst, 1971: 125, fig. 4J; 1986: 85; Ohtaka, 2003: 194, 195, fig. 3c.