Ranatra is a genus of slender predatory insects of the family Nepidae, known as Water mantis, water scorpions or water stick-insects. There are more than 140 Ranatra species found in freshwater habitats around the world, both in warm and temperate regions, with the highest diversity in South America (almost 50 species) and Asia (about 30 species, reviewed in 1972). Fewer are found elsewhere, but include several African, some in North America, three from Australia and three from the Palearctic, notably the relatively well-known European R. linearis. Since Ranatra belongs to the family Nepidae which in turn belongs to the order Hemiptera, Ranatra are considered "true bugs".

These brown insects are primarily found in stagnant or slow-moving water like ponds, marshes and canals, but can also be seen in streams. Exceptionally they have been recorded from hypersaline lakes and brackish lagoons.

Biology

The front legs of bugs in Ranatra are strong and used to grasp prey. They typically eat other insects, tadpoles and small fish, which they pierce with their proboscis and inject a saliva which both sedates and begins to digest their prey. They are sit-and-wait predators that reside among water plants and position themselves head-down with their grasping legs extended out to surprise passing prey. At least one species will also swim in open water at night to catch zooplanktonic organisms. Like other members in the family they have a long tail-like siphon, or breathing tube, on the rear end of their body. The adult body length is generally depending on the exact species, and females average larger than males of the same species. The siphon is typically almost the same size, but varies from less than half the body length to somewhat longer. Two of the largest species are the East Asian R. chinensis and South American R. magna. Ranatra do have wings and they can fly.

The adults are active year-round, except in extreme cold. Their eggs are positioned on plants just below the water surface, but in some species they can be placed in mud. The eggs typically take two to four weeks to hatch and the young take about two months to mature.

Among the four genera in the subfamily Ranatrinae, Austronepa and Goondnomdanepa are restricted to Australia. Cercotmetus from Asia to New Guinea resembles Ranatra, although the former has a distinctly shorter siphon.

Species

The Global Biodiversity Information Facility lists:

1. Ranatra absona Drake & De Carlo, 1953

2. Ranatra acapulcana Drake & De Carlo, 1953

3. Ranatra adelmorpha Nieser, 1975

4. Ranatra aethiopica Montandon, 1903

5. Ranatra akoitachta Nieser, 1996

6. Ranatra ameghinoi De Carlo, 1970

7. Ranatra annulipes Stål, 1854

8. Ranatra attenuata Kuitert, 1949

9. Ranatra australis Hungerford, 1922 i c g b (southern water scorpion)

10. Ranatra bachmanni De Carlo, 1954

11. Ranatra bilobata Tran & Nguyen, 2016

12. Ranatra biroi Lundblad, 1933

13. Ranatra bottegoi Montandon, 1903

14. Ranatra brasiliensis De Carlo, 1946

15. Ranatra brevicauda Montandon, 1905

16. Ranatra brevicollis Montandon, 1910 i c g b

17. Ranatra buenoi Hungerford, 1922 i c g b

18. Ranatra camposi Montandon, 1907

19. Ranatra capensis Germar, 1837

20. Ranatra cardamomensis Zettel, Phauk, Kheam & Freitag, 2017

21. Ranatra chagasi De Carlo, 1946

22. Ranatra chariensis Poisson, 1949

23. Ranatra chinensis Mayr, 1865

24. Ranatra cinnamomea Distant, 1904

25. Ranatra compressicollis Montandon, 1898

26. Ranatra costalimai De Carlo, 1954

27. Ranatra cruzi De Carlo, 1950

28. Ranatra curtafemorata Kuitert, 1949

29. Ranatra denticulipes Montandon, 1907

30. Ranatra digitata Hafiz & Pradhan, 1949

31. Ranatra diminuta Montandon, 1907

32. Ranatra dispar Montandon, 1903

33. Ranatra distanti Montandon, 1910

34. Ranatra doesburgi De Carlo, 1963

35. Ranatra dolichodentata Kuitert, 1949

36. Ranatra dormientis Zhang et al., 1994

37. Ranatra drakei Hungerford, 1922

38. Ranatra ecuadoriensis De Carlo, 1950

39. Ranatra elongata Fabricius, 1790

40. Ranatra emaciata Montandon, 1907

41. Ranatra fabricii Guérin-Méneville, 1857

42. Ranatra falloui Montandon, 1907

43. Ranatra feana Montandon, 1903

44. Ranatra fianarantsoana Poisson, 1963

45. Ranatra filiformis Fabricius, 1790

46. Ranatra flagellata Lansbury, 1972

47. Ranatra flokata Nieser & Burmeister, 1998

48. Ranatra fusca Palisot, 1820 i c g b (brown waterscorpion)

49. Ranatra fuscoannulata Distant, 1904

50. Ranatra galantae Nieser, 1969

51. Ranatra gracilis Dallas, 1850

52. Ranatra grandicollis Montandon, 1907

53. Ranatra grandocula Bergroth, 1893

54. Ranatra hechti De Carlo, 1967

55. Ranatra heoki Tran & Poggi, 2019

56. Ranatra heydeni Montandon, 1909

57. Ranatra horvathi Montandon, 1910

58. Ranatra hungerfordi Kuitert, 1949

59. Ranatra incisa Chen, Nieser & Ho, 2004

60. Ranatra instaurata Montandon, 1914

61. Ranatra insulata Barber, 1939

62. Ranatra jamaicana Drake & De Carlo, 1953

63. Ranatra katsara Nieser, 1997

64. Ranatra kirkaldyi Torre-bueno, 1905 i c g b

65. Ranatra lanei De Carlo, 1946

66. Ranatra lansburyi Chen, Nieser & Ho, 2004

67. Ranatra lenti De Carlo, 1950

68. Ranatra lethierryi Montandon, 1907

69. Ranatra libera Zettel, 1999

70. Ranatra linearis (Linnaeus, 1758) i c g

71. Ranatra longipes Stål, 1861

72. Ranatra lualalai Poisson, 1964

73. Ranatra lubwae Poisson, 1965

74. Ranatra machrisi Nieser & Burmeister, 1998

75. Ranatra macrophthalma Herrich-Schäffer, 1849

76. Ranatra maculosa Kuitert, 1949

77. Ranatra magna Kuitert, 1949

78. Ranatra malayana Lundblad, 1933

79. Ranatra mediana Montandon, 1910

80. Ranatra megalops Lansbury, 1972

81. Ranatra mixta Montandon, 1907

82. Ranatra moderata Kuitert, 1949

83. Ranatra montei De Carlo, 1946

84. Ranatra montezuma Polhemus, 1976

85. Ranatra natalensis Distant, 1904

86. Ranatra natunaensis Lansbury, 1972

87. Ranatra neivai De Carlo, 1946

88. Ranatra nieseri Tran & Nguyen, 2016

89. Ranatra nigra Herrich-Schaeffer, 1849

90. Ranatra nodiceps Gerstaecker, 1873

91. Ranatra nodioeps Gerstaecker, 1873

92. Ranatra obscura Montandon, 1907

93. Ranatra occidentalis Lansbury, 1972

94. Ranatra odontomeros Nieser, 1996

95. Ranatra oliveiracesari De Carlo, 1946

96. Ranatra operculata Kuitert, 1949

97. Ranatra ornitheia Nieser, 1975

98. Ranatra parmata Mayr, 1865

99. Ranatra parvipes Signoret, 1861

100. Ranatra parvula Kuitert, 1949

101. Ranatra pittieri Montandon, 1910

102. Ranatra protense Montandon

103. Ranatra quadridentata Stål, 1862 i c g b

104. Ranatra rabida Buchanan White, 1879

105. Ranatra rafflesi Tran & D.Polhemus, 2012

106. Ranatra rapax Stål, 1865

107. Ranatra recta Chen, Nieser & Ho, 2004

108. Ranatra robusta Montandon, 1905

109. Ranatra sagrai Drake & De Carlo, 1953

110. Ranatra sarmientoi De Carlo, 1967

111. Ranatra sattleri De Carlo, 1967

112. Ranatra schuhi D.Polhemus & J.Polhemus, 2012

113. Ranatra segrega Montandon, 1913

114. Ranatra signoreti Montandon, 1905

115. Ranatra similis Drake & De Carlo, 1953

116. Ranatra siolii De Carlo, 1970

117. Ranatra sjostedti Montandon, 1911

118. Ranatra spatulata Kuitert, 1949

119. Ranatra spinifrons Montandon, 1905

120. Ranatra spoliata Montandon, 1912

121. Ranatra stali Montandon, 1905

122. Ranatra sterea Chen, Nieser & Ho, 2004

123. Ranatra subinermis Montandon, 1907

124. Ranatra sulawesii Nieser & Chen, 1991

125. Ranatra surinamensis De Carlo, 1963

126. Ranatra texana Hungerford, 1930

127. Ranatra thai Lansbury, 1972

128. Ranatra titilaensis Hafiz & Pradhan, 1949

129. Ranatra travassosi De Carlo, 1950

130. Ranatra tridentata Poisson, 1965

131. Ranatra tuberculifrons Montandon, 1907

132. Ranatra unicolor Scott, 1874

133. Ranatra unidentata Stål, 1861

134. Ranatra usingeri De Carlo, 1970

135. Ranatra varicolor Distant, 1904

136. Ranatra varipes Stål, 1861

137. Ranatra vitshumbii Poisson, 1949

138. Ranatra wagneri Hungerford, 1929

139. Ranatra weberi De Carlo, 1970

140. Ranatra williamsi Kuitert, 1949

141. Ranatra zeteki Drake & De Carlo, 1953

Data sources: i = ITIS, c = Catalogue of Life, g = GBIF, b = Bugguide.net

References

External links