Ranatra, Fabricius, 1790

Polhemus, Dan A. & Polhemus, John T., 2013, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. X. Infraorder Nepomorpha-Famlies Belostomatidae And Nepidae, Raffles Bulletin of Zoology 61 (1), pp. 25-45 : 32-33

KEY TO THE SPECIES OF RANATRA OCCURRING IN SINGAPORE AND PENINSULAR MALAYSIA

(modified from Lansbury, 1972)

1. Head with prominent, keel-like tubercle on vertex between the eyes ( Fig. 9 ).............................................................................2

– Head lacking prominent, keel-like tubercle on vertex between the eyes ( Fig. 10 ); if a tubercle present, then small and nodular, prominent and not keel-like....................................................4

2. Respiratory siphon short, approximately one-third the length of the abdomen; male paramere with distal hook and subapical tumescence separated by a narrow incision ( Figs. 11–14 ) ( R. gracilis species group)............................................................3

– Respiratory siphon longer than the length of the abdomen; male paramere with distal hook and subapical tumescence separated by a broad incision ( Figs. 15, 16 )..... R. spinifrons Montandon

3. Ventral prothoracic keel present between fore coxae but then becoming obsolescent posteriorly; body length (excluding siphon) 30–37 mm; middle femur shorter than hind femur; apex of male paramere with distal hook and subapical tubercle separated by a narrow incision, touching at their apices or nearly so ( Figs. 13, 14 )............................................. R. parmata Mayr

– Ventral prothoracic keel running posteriorly from between fore coxae almost entire length of prothorax; body length (excluding siphon) 28–29 mm; middle and hind femora subequal in length; apex of male paramere with distal hook and subapical tubercle separated by a broader incision, apices not touching ( Figs. 11, 12 )................................................................. R. gracilis Dallas

4. Largest tooth on fore femur lying more or less equidistant between base and tip of femur ( Fig. 29 ; R. varipes species group)................................................................. R. varipes Stål

– Largest tooth on fore femur lying clearly nearer to the distal end of the femora than to the base ( Figs. 27, 28 ; R. biroi species group).......................................................................................4

5. Posterior apex of mesosternum pointed or rounded; width of fore femur measured from dorsal margin to apex of largest tooth less than the widest part of the femur basally ( Fig. 27 )........ 5

– Posterior apex of mesosternum truncate; width of fore femur measured from dorsal margin to apex of largest tooth subequal to or greater than the widest part of the femur basally ( Fig. 28 )........................................... R. rafflesi Tran & D. Polhemus

6. Hind tibia distinctly longer than middle tibia; male paramere with a small tooth at apex of distal hook ( Figs. 19, 20 ) .......... ......................................................................... R. longipes Stål

– Middle and hind tibiae subequal in length; male paramere without a small tooth at apex of distal hook ( Figs. 21, 22 ) ..... ........................................................................ R. thai Lansbury

Figures

Figs. 9–10. Ranatra species, left lateral view of head.9, R. parmata, specimen from Indonesia, Sumbawa (CL 2172). 10, R. thai, specimen from Thailand, Chiang Mai Prov. (CL 2201).

Figs. 11–18. Ranatra species, male left parameres, outer view with detail of distal hook. 11, 12, R. gracilis, specimen from Laos, Vientiane Prov. 13, 14, R. parmata, specimen from Indonesia, Sumbawa (CL 2172). 15, 16, R. spinifrons, specimen from Malaysia, Selangor. 17, 18, R. varipes, specimen from Laos, Khammouane Prov.

Figs. 27–29. Ranatra species, forelegs. 27, R. longipes longipes, specimen from Singapore, Nee Soon.28, R. rafflesi, specimen from Singapore, Selatar Reservoir. 29, R. varipes, specimen from Laos, Khammouane Prov.

Figs. 19–24. Ranatra species, male left parameres, outer view with detail of distal hook. 19, 20, R. longipes, specimen from Singapore, Nee Soon. 21, 22, R. thai, specimen from Thailand, Chiang Mai Prov. (CL 2201). 23, 24, R. rafflesi, specimen from Singapore, Selatar Reservoir.