Anisops tahitiensis Lundblad, 1934

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 : 90-91

Anisops tahitiensis Lundblad, 1934

Anisops tahitiensis Lundblad, 1934 ; Brooks, 1951 (redescription); Lansbury, 1964; Fernando & Cheng, 1974; Fernando & Leong, 1976; Kovac & Yang, 1990; Yang & Kovac, 1995; Yang et al. 1999.

Diagnosis. – Sordid white to yellowish somewhat spindle shaped with blackish apex of abdomen and widest in the middle of the body.

Length, male 5.1-6.0, female 5.1-6.3; width, male 1.3-1.5 female 1.3-1.6. Head width 0.9 times the humeral width of pronotum and five to seven times the anterior width of vertex. Male. In dorsal view the head is anteriorly truncate. Synthlipsis about one third the anterior width of vertex. In frontal view tylus swollen and laterally compressed forming a low, rather blunt carina which runs to basal half to two thirds of the frons, anteriorly the carina usually has a narrow slit on the tylus. Rostral prong longer than third rostral segment, originating near its distal ( Fig. 14 ). Labrum without specialized hairs. Forefemur distally somewhat broadly truncate. Stridulatory comb on foretibia with about 23-34 teeth increasing in length towards apex ( Fig. 23 ).

Female. In dorsal view the head is nearly truncate anteriorly; syntlipsis is about 0.3-0.5 times the anterior width of vertex. Tylus slightly convex, not swollen, frons without carina.

Brachypterous form not known.

“Comparative notes” has not been used in this paper, they have been included under “remarks”. The part with a red line in the margin under Anisops tahitiensis should read:

Remarks. – Similar to A. nigrolineatus , see under that species.

Brooks (1951) gives as body length for both sexes 5.1-5.5, although Lundblad (1934) stated that the length of a male is about 6.0 and of female 6.7. Specimens from West Malaysia had a body length of male 5.3-6.0 female 5.5-6.3 (pers. observ.). The figure of the stridulatory comb given by Lansbury (1964) gives the impression that the width of the teeth increases from base to apex. Lundblad (1934) states the opposite, confirmed by my observations ( Figs. 23 , 24).

As already observed by Lansbury (1964), with Brooks (1951) SE Asian males of this species tend to key out to A. fijiensis Brooks , because the head is less than seven times as wide as synthlipsis (5.0-6.5 times in specimens from W. Malaysia studied). However, A. fijiensis males have the apex of the forefemur distinctly narrowed.

Distribution. – From Andaman Islands and Vietnam through Malesia to Australia, Tahiti, Guadalcanal and Okinawa ( Lansbury, 1964). This species has been recorded from Johor, Pahang, Perak, Selangor and Singapore (Fernando & Cheng, 1974; Fernando & Leong, 1976; Kovac & Yang, 1990; Yang & Kovac, 1995; Yang et al. 1999). There is a also sample from Trengganu in ZRC. This species inhabits stagnant waters (lakes, ponds and pools, swamps) confirming the observation that it is not found in running water (Yang & Kovac, 1995).

SUBFAMILY NOTONECTINAE LATREILLE

Remarks. – Apart from various external morphological features, Notonectinae differ from Anisopinae by the lack of haemoglobin cells. During a dive they carry a large external air store under the hemielytra and in the ventral abdominal channels closed ventrally by hair fringes. In addition there is, at least in Notonecta , a film of air on the outside of the hemielytra which functions as a physical gill. Unlike Anisopinae , Notonectinae cannot regulate their air store, so they tend to float upward when not actively swimming. Some species cling to objects under water to stay submerged, other species simply float against the underside of the surface film while waiting for prey (e.g. Nychia sappho and some species of Enithares ). With their large eyes they detect eventual prey beneath them. In addition they have sensory organs on their legs with which they can locate prey that has fallen in the water by the waves such struggling animals cause in the surface film.

Figures

Figs. 12-17. Anisops male, head in lateral view. 12 A. barbatus; 13 A. bouvieri; 14 A.tahitiensis; 15 A.kuroiwae; 16 A. exiguus; 17 A. lansburyi. p = rostral prong; t = tylus.

Figs. 21-23. Anisops, male, stridular comb. 21 A. lansburyi; 22 A. nigrolineatus; 23 A. tahitiensis.