Nematodes from the Strait of Magellan and the Beagle Channel (Chile): the genera Cervonema and Laimella (Comesomatidae: Nematoda)

Abstract

Five species of Cervonema and four species of Laimella are described from the Strait of Magellan and the Beagle Channel, Chile, six species of which are new to science. Cervonema chilensisn. sp. and Cervonema hermanin. sp. are separated from other known species of Cervonema by a short cervical region (less than one head diameter from the front end to the anterior border of the amphids). Cervonema chilensisn. sp. is characterised by a tail length of 5 anal diameters with posterior half filiform; Cervonema hermani n. sp. is characterised by a tail length of 6–9 anal diameter and posterior part (75%) cylindrical. Cervonema shiaen. sp. is characterised by the cephalic seta 4 μm long, amphids 9–10 μm in diameter; spicules 16 μm long and 0.8–0.9 abd; tail 4.7–5.4 anal diameter and 50% posterior part filiform; 4–5 minute precloacal supplements. Laimella subterminatan. sp. is characterised by the subterminal position of the buccal cavity which separates it from the other species of the genus. Laimella annaen. sp. is characterised by the head diameter 9–11 μm, cephalic setae and external labial setae 9 + 5 μm long, respectively, amphids 7 μm in diameter; spicules 28–30 μm long; tail 14–17 anal diameter and posterior part (75%) filiform; 5 precloacal supplements. Laimella sandraen. sp. is very close to Laimella annaen.sp. in having similar cephalic sensilla, amphids and spicules. Laimella sandraen. sp., however, can be separated from L.annaen. sp. by the shape of head and the structure of sperm cells, the total body length and the cylindrical part of tail. Cervonema papillatum Jensen, 1988, C. tenuicauda (Stekhoven, 1950) and L. longicauda Cobb, 1920 are found in this area as well. The key of all known species of Cervonemaand Laimellais presented.