Anisops niveus (Fabricius, 1775)

Nieser, Nico, 2004, Guide To Aquatic Heteroptera Of Singapore And Peninsular Malaysia Iii. Pleidae And Notonectidae, Raffles Bulletin of Zoology 52 (1), pp. 79-96 : 88-89

Anisops niveus (Fabricius, 1775)

Notonecta nivea Fabricius, 1775 .

Anisops nivea - Brooks, 1951 (redescription); Fernando & Cheng, 1974; Fernando & Leong, 1976.

Diagnosis. – Pale to dark, spindle shaped, greatest width about halfway the body.

Length, male 4.8-5.1, female 4.8-5.4; width, male 1.2-1.4, female 1.3-1.8. Head width 0.9 times the humeral width of pronotum and four to five times the anterior width of vertex. Male. In dorsal view the head is anteriorly truncate with the vertex very slightly indented. Synthlipsis about one third the anterior width of vertex. In frontal view tylus and frons are excavate with two lateral carinae on each side. The median groove runs up to halfway between the eyes where the outer carinae meet in an acuminate apex ( Fig. 18 ). Rostral prong shorter than third rostral segment, originating near its proximal margin. Labrum with rather long hairs at base, the lateral ones forming two tufts which curve upwards along the carinae of the tylus excavation; the middle hairs often united into a small tuft which points downward over the apex of labrum. Forefemur apically somewhat narrowed. Foretibia stout, stridulatory comb with about 13 teeth of equal length. Female. In dorsal view the head is nearly truncate anteriorly with the vertex slightly extending in front of eyes; the syntlipsis is over one third to nearly half the anterior width of vertex. Tylus flat, not swollen.

Brachypterous form not known.

Remarks. – Males clearly recognized by the structure of the frons. Females are of about the same length as A. lansburyi and only slightly larger than A. exiguus females. Both of these species have a relatively narrower body and a distinctly narrower synthlipsis.

Distribution. – India through SE Asia to Sumatra ( Brooks, 1951). Fernando & Cheng (1974) and Fernando & Leong (1976) recorded it from Singapore and Johor. In addition there are specimens in three samples from Melaka in the ZRC.

Figures

Figs. 18-20. Anisops male, head in frontal view; 19-20 rostrum removed. 18 A. niveus; 19 A. kuroiwae; 20 A. nasutus. t = tylus.