Ranatra Fabricius 1790
Creators: name: Polhemus, Dan A.
name: Polhemus, John T.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Nepidae
Ranatra

description: 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
description: Published as part of Polhemus, Dan A. & Polhemus, John T., 2013, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. X. Infraorder Nepomorpha-Famlies Belostomatidae And Nepidae, pp. 25-45 in Raffles Bulletin of Zoology 61 (1) on pages 32-33, DOI: 10.5281/zenodo.5351508