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Ranatra

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 <small>Drake & De Carlo, 1953</small>
  2. Ranatra acapulcana <small>Drake & De Carlo, 1953</small>
  3. Ranatra adelmorpha <small>Nieser, 1975</small>
  4. Ranatra aethiopica <small>Montandon, 1903</small>
  5. Ranatra akoitachta <small>Nieser, 1996</small>
  6. Ranatra ameghinoi <small>De Carlo, 1970</small>
  7. Ranatra annulipes <small>Stål, 1854</small>
  8. Ranatra attenuata <small>Kuitert, 1949</small>
  9. Ranatra australis <small>Hungerford, 1922</small><span style="color:gray"><sup> i c g b</sup></span> (southern water scorpion)
  10. Ranatra bachmanni <small>De Carlo, 1954</small>
  11. Ranatra bilobata <small>Tran & Nguyen, 2016</small>
  12. Ranatra biroi <small>Lundblad, 1933</small>
  13. Ranatra bottegoi <small>Montandon, 1903</small>
  14. Ranatra brasiliensis <small>De Carlo, 1946</small>
  15. Ranatra brevicauda <small>Montandon, 1905</small>
  16. Ranatra brevicollis <small>Montandon, 1910</small><span style="color:gray"><sup> i c g b</sup></span>
  17. Ranatra buenoi <small>Hungerford, 1922</small><span style="color:gray"><sup> i c g b</sup></span>
  18. Ranatra camposi <small>Montandon, 1907</small>
  19. Ranatra capensis <small>Germar, 1837</small>
  20. Ranatra cardamomensis <small>Zettel, Phauk, Kheam & Freitag, 2017</small>
  21. Ranatra chagasi <small>De Carlo, 1946</small>
  22. Ranatra chariensis <small>Poisson, 1949</small>
  23. Ranatra chinensis <small>Mayr, 1865</small>
  24. Ranatra cinnamomea <small>Distant, 1904</small>
  25. Ranatra compressicollis <small>Montandon, 1898</small>
  26. Ranatra costalimai <small>De Carlo, 1954</small>
  27. Ranatra cruzi <small>De Carlo, 1950</small>
  28. Ranatra curtafemorata <small>Kuitert, 1949</small>
  29. Ranatra denticulipes <small>Montandon, 1907</small>
  30. Ranatra digitata <small>Hafiz & Pradhan, 1949</small>
  31. Ranatra diminuta <small>Montandon, 1907</small>
  32. Ranatra dispar <small>Montandon, 1903</small>
  33. Ranatra distanti <small>Montandon, 1910</small>
  34. Ranatra doesburgi <small>De Carlo, 1963</small>
  35. Ranatra dolichodentata <small>Kuitert, 1949</small>
  36. Ranatra dormientis <small>Zhang et al., 1994</small>
  37. Ranatra drakei <small>Hungerford, 1922</small>
  38. Ranatra ecuadoriensis <small>De Carlo, 1950</small>
  39. Ranatra elongata <small>Fabricius, 1790</small>
  40. Ranatra emaciata <small>Montandon, 1907</small>
  41. Ranatra fabricii <small>Guérin-Méneville, 1857</small>
  42. Ranatra falloui <small>Montandon, 1907</small>
  43. Ranatra feana <small>Montandon, 1903</small>
  44. Ranatra fianarantsoana <small>Poisson, 1963</small>
  45. Ranatra filiformis <small>Fabricius, 1790</small>
  46. Ranatra flagellata <small>Lansbury, 1972</small>
  47. Ranatra flokata <small>Nieser & Burmeister, 1998</small>
  48. Ranatra fusca <small>Palisot, 1820</small><span style="color:gray"><sup> i c g b</sup></span> (brown waterscorpion)
  49. Ranatra fuscoannulata <small>Distant, 1904</small>
  50. Ranatra galantae <small>Nieser, 1969</small>
  51. Ranatra gracilis <small>Dallas, 1850</small>
  52. Ranatra grandicollis <small>Montandon, 1907</small>
  53. Ranatra grandocula <small>Bergroth, 1893</small>
  54. Ranatra hechti <small>De Carlo, 1967</small>
  55. Ranatra heoki <small>Tran & Poggi, 2019</small>
  56. Ranatra heydeni <small>Montandon, 1909</small>
  57. Ranatra horvathi <small>Montandon, 1910</small>
  58. Ranatra hungerfordi <small>Kuitert, 1949</small>
  59. Ranatra incisa <small>Chen, Nieser & Ho, 2004</small>
  60. Ranatra instaurata <small>Montandon, 1914</small>
  61. Ranatra insulata <small>Barber, 1939</small>
  62. Ranatra jamaicana <small>Drake & De Carlo, 1953</small>
  63. Ranatra katsara <small>Nieser, 1997</small>
  64. Ranatra kirkaldyi <small>Torre-bueno, 1905</small><span style="color:gray"><sup> i c g b</sup></span>
  65. Ranatra lanei <small>De Carlo, 1946</small>
  66. Ranatra lansburyi <small>Chen, Nieser & Ho, 2004</small>
  67. Ranatra lenti <small>De Carlo, 1950</small>
  68. Ranatra lethierryi <small>Montandon, 1907</small>
  69. Ranatra libera <small>Zettel, 1999</small>
  70. Ranatra linearis <small>(Linnaeus, 1758)</small><span style="color:gray"><sup> i c g</sup></span>
  71. Ranatra longipes <small>Stål, 1861</small>
  72. Ranatra lualalai <small>Poisson, 1964</small>
  73. Ranatra lubwae <small>Poisson, 1965</small>
  74. Ranatra machrisi <small>Nieser & Burmeister, 1998</small>
  75. Ranatra macrophthalma <small>Herrich-Schäffer, 1849</small>
  76. Ranatra maculosa <small>Kuitert, 1949</small>
  77. Ranatra magna <small>Kuitert, 1949</small>
  78. Ranatra malayana <small>Lundblad, 1933</small>
  79. Ranatra mediana <small>Montandon, 1910</small>
  80. Ranatra megalops <small>Lansbury, 1972</small>
  81. Ranatra mixta <small>Montandon, 1907</small>
  82. Ranatra moderata <small>Kuitert, 1949</small>
  83. Ranatra montei <small>De Carlo, 1946</small>
  84. Ranatra montezuma <small>Polhemus, 1976</small>
  85. Ranatra natalensis <small>Distant, 1904</small>
  86. Ranatra natunaensis <small>Lansbury, 1972</small>
  87. Ranatra neivai <small>De Carlo, 1946</small>
  88. Ranatra nieseri <small>Tran & Nguyen, 2016</small>
  89. Ranatra nigra <small>Herrich-Schaeffer, 1849</small>
  90. Ranatra nodiceps <small>Gerstaecker, 1873</small>
  91. Ranatra nodioeps <small>Gerstaecker, 1873</small>
  92. Ranatra obscura <small>Montandon, 1907</small>
  93. Ranatra occidentalis <small>Lansbury, 1972</small>
  94. Ranatra odontomeros <small>Nieser, 1996</small>
  95. Ranatra oliveiracesari <small>De Carlo, 1946</small>
  96. Ranatra operculata <small>Kuitert, 1949</small>
  97. Ranatra ornitheia <small>Nieser, 1975</small>
  98. Ranatra parmata <small>Mayr, 1865</small>
  99. Ranatra parvipes <small>Signoret, 1861</small>
  100. Ranatra parvula <small>Kuitert, 1949</small>
  101. Ranatra pittieri <small>Montandon, 1910</small>
  102. Ranatra protense <small>Montandon</small>
  103. Ranatra quadridentata <small>Stål, 1862</small><span style="color:gray"><sup> i c g b</sup></span>
  104. Ranatra rabida <small>Buchanan White, 1879</small>
  105. Ranatra rafflesi <small>Tran & D.Polhemus, 2012</small>
  106. Ranatra rapax <small>Stål, 1865</small>
  107. Ranatra recta <small>Chen, Nieser & Ho, 2004</small>
  108. Ranatra robusta <small>Montandon, 1905</small>
  109. Ranatra sagrai <small>Drake & De Carlo, 1953</small>
  110. Ranatra sarmientoi <small>De Carlo, 1967</small>
  111. Ranatra sattleri <small>De Carlo, 1967</small>
  112. Ranatra schuhi <small>D.Polhemus & J.Polhemus, 2012</small>
  113. Ranatra segrega <small>Montandon, 1913</small>
  114. Ranatra signoreti <small>Montandon, 1905</small>
  115. Ranatra similis <small>Drake & De Carlo, 1953</small>
  116. Ranatra siolii <small>De Carlo, 1970</small>
  117. Ranatra sjostedti <small>Montandon, 1911</small>
  118. Ranatra spatulata <small>Kuitert, 1949</small>
  119. Ranatra spinifrons <small>Montandon, 1905</small>
  120. Ranatra spoliata <small>Montandon, 1912</small>
  121. Ranatra stali <small>Montandon, 1905</small>
  122. Ranatra sterea <small>Chen, Nieser & Ho, 2004</small>
  123. Ranatra subinermis <small>Montandon, 1907</small>
  124. Ranatra sulawesii <small>Nieser & Chen, 1991</small>
  125. Ranatra surinamensis <small>De Carlo, 1963</small>
  126. Ranatra texana <small>Hungerford, 1930</small>
  127. Ranatra thai <small>Lansbury, 1972</small>
  128. Ranatra titilaensis <small>Hafiz & Pradhan, 1949</small>
  129. Ranatra travassosi <small>De Carlo, 1950</small>
  130. Ranatra tridentata <small>Poisson, 1965</small>
  131. Ranatra tuberculifrons <small>Montandon, 1907</small>
  132. Ranatra unicolor <small>Scott, 1874</small>
  133. Ranatra unidentata <small>Stål, 1861</small>
  134. Ranatra usingeri <small>De Carlo, 1970</small>
  135. Ranatra varicolor <small>Distant, 1904</small>
  136. Ranatra varipes <small>Stål, 1861</small>
  137. Ranatra vitshumbii <small>Poisson, 1949</small>
  138. Ranatra wagneri <small>Hungerford, 1929</small>
  139. Ranatra weberi <small>De Carlo, 1970</small>
  140. Ranatra williamsi <small>Kuitert, 1949</small>
  141. Ranatra zeteki <small>Drake & De Carlo, 1953</small>

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

References

External links