Acantholaimus(chromadoridae:nematoda)fromtheIndianOcean:

Abstract

Seven species of the Acantholaimus are described. Acantholaimu s vermeuleni sp.n. is characterised by labial and cephalicsensilla that are located at the same level, two post amphidialsetae on the dorso-lateralside and a poorly developed stoma without distinct teeth. Acantholaimu s verscheld i sp.n. is characterized by a narrow elongate pharyngeal region, a long stoma with distinct teeth and short (4–7 m) cephalic sensilla. Acantholaimus heipi sp.n.is characterized by a narrow elongate pharyngeal region,well developed teeth in the stoma and long cephalic sensilla (11–13 m). Acantholaimus elegans Jensen 1988 has a narrow anterior pharyngeal region that increases in width posteriorly, it has setae before and after the amphidson both sides and stoma with well developed teeth. Acantholaimus gathumai sp.n. is characterized by long cephalic (10–15 m) and somatic (8–10 m) setae and lateral differentiation with fine dots (5–7 m in width). Acantholaimu s geraerti sp.n. has long cephalic sensilla (15–19 m)andnarrow(4–6 m)distinct lateral differentiation. Acantholaimus invaginatumsp.n.ischaracterised by very long cephalicsetae(16–21 m),severalsetaeatthepharyngealregionandwidelateraldifferentiationwith finedots,of the stoma is invaginated. Distribution of the different species of Acantholaimus encountered in the four transects studied is also described.