Five new species of Nepomorpha (Heteroptera) from southeast Asia

Abstract

Part of the material was collected while preparing a survey of aquatic and semiaquatic bugs of North Thailand, supported by the University of Chiang Mai, Thailand, and a grant from the UyttenboogaartEliasen Stichting, Amsterdam, The Netherlands. Measurements are in mm and based on five specimens, if available, of each sex taken from the sample containing the holotype. Measurements are presented as the mean ‘x-’ followed by the standard deviation based on sample ‘s’. For some measurements the actual value for the holotype is added between brackets {}. If only two or three specimens are available the measurements are presented as range, in case of three specimens with the mean between . The mean values of measurements of leg segments are presented in table 1. If there is no significant difference in length of leg segments between the sexes of a species, the measurements are united. Length and width refer to body length and maximum width, with the body in a horizontal plane. Body length is measured from the anterior point of head to the posterior point of hemielytra in dorsal view. The width of an eye in Micronecta is measured along its posterior margin. In Aphelocheirus the head is measured with its own longitudinal axis horizontal; the width of an eye is here the maximum width perpendicular on the longitudinal axis of the head. A special ratio, used in Micronecta, is the ocular index, which is calculated as two times the synthlipsis (S) divided by the width of the head across the eyes (D) minus the synthlipsis: 2S/(D-S). The synthlipsis is the smallest distance between the eyes posteriorly. In Anisops, where the synthlipsis is often very narrow, the ocular index based on vertex (Nieser 1975) is used. This index is defined as two times the anterior width of vertex (V) divided by the width of head (D) minus anterior width of vertex: 2V/(D-V). These ocular indexes eliminate to certain extent the errors in comparing measurements of D, S and V due to not perfect orientation of the head when measuring. Leg segments are measured in ventral view with the segment under consideration in a horizontal plane.