Mononchus risoceiae, new species (Nematoda, Mononchidae)

Abstract

A new species of Mononchus, which lives on nematode and protozoa, was described. This species, called Mononchus (Iotonchus) risoceiae, was found in plots of ornamental plants and in cultivated fields near São Paulo. M. risoceiae differs from its nearest related species M. brachylaimus Cobb by the following characteristics: a) absence of the rudimentary teeth which are observed in the M. brachylaimus species; b) shorter tail: female C = 5,7 - 10,0 : 16,6; male c= 8,2 - 9,7 : 16,6; c) smaller size of the pharynx: male: 0,055 x 0,037 mm : 0,080 x 0,077 mm; female: 0,062 x 0,052 mm : 0,076 x 0,076 mm . And it differs from M. tenuidentatus Kreis as follows : a) its longer size, female : 2,682 - 2,817 mm : 1,968 mm; b) its more developed pharynx tooth; c) the length of the pharynx which is in M. tenuidentatus twice its wideness, and in M. risoceiae, less than twice.