Dero obtusa d’Udekem, 1855

Righi, Gilberto & Hamoui, Viviane, 2002, Oligochaeta, Naididae Of The West Indies And Adjacent Regions, Papéis Avulsos de Zoologia 42 (6), pp. 119-167 : 127-128

Dero obtusa d’Udekem, 1855

Dero obtusa d’Udekem, 1855: 549 , fig. 1; Marcus, 1943: 56, figs. 41-42; 1944: 67, fig. 57; Cordero, 1951: 231.

Dero (D.) obtusa ; Sperber, 1948: 180, figs. 19F, 20A, pl. 8, fig. 5; Harman, 1974: 21; 1982a: 292; Di Persia, 1976: 2, figs. 1-4; 1980a: 91; Botea, 1983: 28, fig. 9F-J; Dumnicka, 1986: 268, fig. 2a-d; Marchese, 1986: 237; Martinez-Ansemil & Giani, 1986: 113.

Material: New Providence 548: 3 specimens. Cayman Brac 007: 7 specimens. Jamaica 026: 1 specimen . Puerto Rico 705: 14 specimens . St. Martin 529: 24 specimens . Marie Galante 752: 1 specimen; 756A: 1 specimen; 767: 1 specimen. Dominique 847: 2 specimens. Martinique 851: 1 specimen; 852: 178 specimens. Barbados 782: 169 specimens ; 867: 2 specimens; 868: 7 specimens. Trinidad 795: 4 specimens . Bonaire 44c: 3 specimens . Curaçao 339: 21 specimens . Venezuela 920: 6 specimens . Suriname 119: 3 specimens ; 642: 12 specimens; 642A: 30 specimens; 646: 5 specimens; 923: 3 specimens; 928: 1 specimen. Habitat: Limnetic to oligohaline; salinity 0.02-3.8%.

Distribution: Asia ( Chen, 1940; Chekanovskaya, 1962). Europa ( Sperber, 1948; Hrabe, 1981). Africa ( Brinkhurst, 1966). North America ( Brinkhurst, 1964). Neotropical Region: Argentina: Prov. Cordoba, Corrientes, Santa Fe ( Di Persia, 1980a; Marchese, 1986). Bolivia: Prov. La Paz and El Beni (Martinez-Ansemil & Giani, 1986). Brazil: São Paulo State ( Marcus, 1943; 1944). Surinam ( Harman, 1974). Venezuela: Dept. Central and Falcon. Haiti. Anegada ( Dumnicka, 1986). Cuba ( Botea, 1983). Costa Rica ( Harman, 1982a). Curaçao, Bonaire, Trinidad, Barbados, Martinique, Dominique, Marie Galante, St. Martin, Puerto Rico, Jamaica, Cayman Brac, New Providence (Righi & Hamoui).

Remarks: The shape and measures of the setae in our worms agree with the South-American ( Marcus, 1943; Harman, 1974; Di Persia, 1976) and European ones ( Sperber, 1948; Hrabe, 1981). Perhaps due to contraction and preservation it was not possible to distinguish the dorsal lip and the marginal expansions of the branchial fossa, which are so characteristic of living animals. In the majority of our animals the stomach is restricted to segment VIII but occasionally it is in X; in Brazilian specimens ( Marcus, 1943) it is in VIII-IX and in the European ones in IX, IX-X or X ( Sperber, 1948). The division-zone of the Caribbean specimens is in XII-XIX, usually in XV or XVI; in Brazilian specimens it is in XVIII-XX and in European ones in XVIII-XIX. The great variability of these characteristics and discrepancies in the reproductive organs ( Beddard, 1889; Chen, 1940; Marcus, 1944) makes us see Dero obtusa as an highly polymorphic species or, more probably, a complex of species indistinguishable by setal characteristics.