Hydrometra, Latreille, 1797

Yang, Chang Man & Zettel, Herbert, 2005, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. V. Hydrometridae, Raffles Bulletin of Zoology 53 (1), pp. 79-97 : 82-84

Key to the species of Hydrometra

(modified from Polhemus & Polhemus,1995 and Zettel & Chen, 1996)

1. Anteclypeus distinctly shorter than wide, with anteromedial depression, and with slightly concave anterior margin ( Figs. 20 , 34 , 43 , 52 ) ............................................................................... 2

– Anteclypeus usually longer than wide, without anteromedial depression, and with round or pointed anterior ( Figs. 12 , 38 , 78, 81 ). [Except in H. ripicola , anteclypeus slightly shorter than wide and anterior margin truncate ( Fig. 86)] ........................5

2. Tarsus of middle leg very short, MTiI = 9-11. Venter light brown. Male: S7 with pair of large pad-like projections. Female: PT8 absent, S7 strongly produced caudad ( Figs. 20-24 ); apt. ........ ................................................. H. brevitarsus Zettel & Yang

– Tarsus of middle leg long, MTiI <7. Venter blackish brown. Male: S7 without pair of large pad-like projections. Female: PT8 present, S7 not strongly produced ...................................... 3

3. Male: Sg8 without paired tufts of setae, S7 not depressed, with paired patches of short setae posterolaterally. Female: T8 directed straight caudad ( Figs. 52-55 ); brpt (or mapt) ............ .............................................. H. julieni Hungerford & Evans

– Male: Sg8 with paired tufts of laterad directed short setae ( Figs. 36 , 45, 47 ). S7 posterior half depressed, dispersed with long setae ( Figs. 35 , 44 ). Female: T8 directed ventrocaudad ( Figs. 37 , 46 ) ................................................................................... 4

4. Wing straps of brachypterous morph distinctly surpassing middle of tergite 2, usually nearly reaching its hind margin. Male: longer paired tufts of setae on Sg8, and extending to posterior margin. Depression of S7 short. Female: abdomen weakly upcurved, T8 straight or weakly downcurved. S7 with distinct posteromedial downwarded button-like protrusion ( Figs. 34-37 ); brpt or mapt ........................................... H. gilloglyi Hungerford & Evans

– Wing straps of brachypterous morph usually not (very rarely weakly) surpassing middle of tergite 2. Male: shorter paired tufts of setae on Sg8 not reaching posterior margin. Depression of S7 long. Female: abdomen distinctly upcurved, T8 distinctly downcurved. S7 with normal or slight posteromedial protrusion ( Figs. 43-47 ); brpt or mapt ..... H. heoki paya Zettel & Yang (Also key to H. heoki heoki Zettel & Yang , brpt (or mapt); an allopatric subspecies distributed in Borneo)

5. Male: S7 modified, T8 fused with sternite 8 ....................... 6

– Female: S7 not modified, T8 separated from sternite 8 .... 20

6. Anteclypeus broad with parallel sides in dorsal view (except in H. carinata , sides not parallel, but with broadly rounded anterior) ( Figs. 25 , 65 , 86) .................................................................. 7

– Anteclypeus somewhat triangular or conical shape, with pointed or bluntly rounded anterior in dorsal view ( Figs. 5 , 12, 16 , 30 , 38,48,56,60,74,78,81 ) .................................................... 9

7. S7 ventral outline straight, surface normal, with pair of clusters of spines or thorns ................................................................ 8

– S7 ventral outline not straight, and with strongly concave posterior, surface with distinct transverse groves; anteriorly with paired large "fleshy" tubercle processes, but without clusters of spine-like process ( Figs. 65-67 ); brpt (or mapt) ...................... ................................................... H. longicapitis Torre-Bueno

8. S7 anteriorly with paired humps bearing clusters of short thorns. Maxillary plate of normal size ( Figs. 86-88); apt ................... ............................... [ H. ripicola Andersen ] (North Thailand)

– S7 without paired humps; clusters of spines located 1/3 from anterior margin. Maxillary plate very large ( Figs. 25, 26 , 28, 29 ); brpt (or mapt) ......... H. carinata Polhemus & Polhemus

9. S7 anteriorly with a pair of processes, which usually consists of a cluster of spines or setae ( Figs. 31, 32 , 49, 50 , 75 , 76, 79 ) ............................................................................................. 15

– S7 anteriorly without a pair of processes .......................... 10

10. S7 ventrally strongly concave in lateral view, with dispersed long setae ( Figs. 40 , 57 ), but without distinct paired patches of short hairs ............................................................................ 11

– S7 ventral outline straight in lateral view, with distinct paired patches of dense short hairs ( Figs. 13, 17 , 70 ) or with dispersed long setae ( Figs. 61 , 82 ) ..................................................... 12

11. MTaI about 2.3. Sg8 with strong posterolateral outwarded corners. Body colour medium to blackish brown ( Figs. 56-59 ); mapt (or brpt) ................. H. kelantan Polhemus & Polhemus

– MTaI about 1.8. Sg8 with week posterolateral corners. Body colour light to medium brown ( Figs. 38-42 ); mapt (or brpt) .. .................................................................. H. greeni Kirkaldy

12. S7 with paired patches of short and dense hairs, S6 and S7 without dispersed long setae. Hind femur lined with long erect hairs (hairs sometimes “sticking” to femur and then not well visible in dry specimens) .................................................... 13

– S7 without paired patches of short hairs, S6 and S7 with dispersed long setae. Hind femur not lined with long hairs ... ............................................................................................... 19

13. S7 with distinct rounded patches of short hairs near to middle ( Figs. 12-14 ); mapt or brpt ....... [ H. annamana Hungerford & Evans ] ( Thailand, Vietnam and southern China)

– S7 paired patches of short hairs not distinctly rounded, located posteriorly ( Figs. 17 , 70 ) .................................................... 14

14. Patches of hairs not extending to posterior margin of S7 ( Figs. 69-71 ); mapt or brpt ............ H. maidli Hungerford & Evans

– Patches of hairs extending to posterior and posterolateral margins of S7 ( Figs. 16-18 ); brpt or mapt .... [ H. borneensis Zettel & Yang ] (Borneo, an allopatric species of H. maidli )

15. Anteclypeus with very acute or spine-like anterior ( Figs. 5 , 78 ). S7 appearing bare except anteriorly with a pair of tightly clustered thorn-like processes ( Figs. 6 , 79, 80 ). Posterior margin of Sg8 truncate or round .................................................... 16

– Anteclypeus blunt ( Figs. 30 , 48 , 74 ). S7 with some long and short setae, anteriorly with a pair of loosely clustered setae ( Figs. 31, 32 , 49, 50 , 75 , 76 ). Posterior margin of Sg8 round .... 17

16. Anteclypeus terminating in long slender spine ( Fig. 5 ). S7 with pair of thorn-like processes close to midline, distance between the thorns approximately 2 times their length ( Figs. 6, 7 ). Body colour blackish brown; apt ....................................................... ....................................... H. chaweewanae Sites & Polhemus

– Anteclypeus acute, but not spine-like ( Fig. 78 ). S7 with thorn-like processes distant to midline, distance between the thorns approximately 4 times their length ( Figs. 79, 80 ). Body colour light brown; brpt (or mapt) .................. H. okinawana Drake

17. S7 with stronger concave ventral outline in lateral view, and with dispersed long setae ventrally ( Figs. 49, 50 ). Anteclypeus small ( Fig. 48 ); brpt .......................... H. jaczewskii Lundblad

– S7 with more or less straight ventral outline in lateral view, without dispersed long setae, but with more or less obvious paired patches of short hairs posteriorly. Anteclypeus not obviously small ................................................................... 18

18. S 7 in posterior half with well-developed hair patches. Minimum distance of mesocoxae approximately one third of coxa width ( Figs. 74-76 ); apt (or mapt) .. [ H. mindoroensis J. Polhemus ] (from northern Borneo eastwards; also key to H. lombok Polhemus & Polhemus , from the Lesser Sunda Islands)

– S 7 in posterior half with weakly developed hair patches ( Figs. 31, 32 ). Minimum distance of mesocoxae approximately one fifth of coxa width; apt ... H. cracens Polhemus & Polhemus

19. Sg8 ending in strong posterolateral corners. Anterior of anteclypeus narrowly rounded, sides of anteclypeus convex ( Figs. 60-62 ); mapt (or brpt) .............. H. lineata Eschscholtz

– Sg8 ending in weak posterolateral corners. Anteclypeus with more pointed anterior ( Figs. 81-83 ); mapt (or brpt) ................ ............................................................ H. orientalis Lundblad

Figures

Figs. 20-27: 20-24: Hydrometra brevitarsus Zettel & Yang; 20. Apex of head, dorsal view showing anteclypeus; 21. Male terminal abdomen, lateral view; 22. Male terminal abdomen, ventral view; 23. Female terminal abdomen, dorsal view; 24. Female terminal abdomen, lateral view. 25-27: Hydrometra carinata Polhemus & Polhemus; 25. Apex of head, dorsal view showing anteclypeus; 26. Head, lateral view (AC, anteclypeus; Gl, gular lobe; MXP, maxillary plate); 27. Female terminal abdomen, lateral view.

Figs. 28-35: 28-29: Hydrometra carinata Polhemus & Polhemus, male terminal abdomen; 28. lateral view; 29. cluster of spines on sternite 7. 30-33: Hydrometra cracens Polhemus & Polhemus; 30. Apex of head, dorsal view showing anteclypeus; 31. Male terminal abdomen, lateral view; 32. Male terminal abdomen, ventral view; 33. Female terminal abdomen, lateral view. 34-35: Hydrometra gilloglyi Polhemus & Polhemus; 34. Apex of head, dorsal view showing anteclypeus; 35. Male terminal abdomen, lateral view.

Figs. 36-43: 36-37: Hydrometra gilloglyi Polhemus & Polhemus; 36. Male terminal abdomen, vental view; 37. Female terminal abdomen, lateral view, note the posterior-median protrusion of sternite 7. 38-42: Hydrometra greeni Kirkaldy; 38. Apex of head, dorsal view showing anteclypeus; 39. Head, lateral view (Gl, gular lobe; MXP, maxillary plate); 40. Male terminal abdomen, lateral view; 41. Male terminal abdomen, ventral view; 42. Female terminal abdomen, lateral view; 43. Hydrometra heoki heoki Zettel & Yang, apex of head, dorsal view showing anteclypeus.

Figs.52-59:52-55: Hydrometra julieni Hungerford & Evens; 52 Apex of head, dorsal view showing anteclypeus; 53. Male terminal abdomen, lateral view; 54. Male terminal abdomen, ventral view; 55. Female terminal abdomen, lateral view. 56-59: Hydrometra kelantan Polhemus & Polhemus; 56. Apex of head, dorsal view showing anteclypeus; 57. Male terminal abdomen, lateral view; 58. Male terminal abdomen, ventral view; 59. Female terminal abdomen, lateral view.

Figs. 12-19: 12-15: Hydrometa annamana Hungerford & Evans; 12. Apex of head, dorsal view showing anteclypeus (AC); 13. Male terminal abdomen, lateral view; 14. Male terminal abdomen, ventral view; 15. Female terminal abdomen, lateral view. 16-19: Hydrometra borneensis Zettel & Yang; 16. Apex of head, dorsal view showing anteclypeus; 17. Male terminal abdomen, lateral view; 18. Male terminal abdomen, ventral view; 19. Female terminal abdomen, lateral view.

Figs. 76-83: 76-77: Hydrometra mindoroensis J. Polhemus; 76. Male terminal abdomen, ventral view; 77. Female terminal abdomen, lateral view. 78-80: Hydrometra okinawana Drake; 78. Apex of head, dorsal view showing anteclypeus; 79. Male terminal abdomen, lateral view. 80. Male, cluster of tightly thorns on sternite 7; 81-83: Hydrometra orientalis Lundblad; 81. Apex of head, dorsal view showing anteclypeus. 82. Male terminal abdomen, lateral view; 83. Male terminal abdomen, ventral view.

Figs. 44-51: 44-46: Hydrometra heoki heoki Zettel & Yang; 44. Male terminal abdomen, lateral view; 45. Male terminal abdomen, ventral view; 46. Female terminal abdomen, lateral view; 47. Hydrometra heoki paya Zettel & Yang, male termainal abdomen, ventral view; 48-51: Hydrometra jaczewskii Lundblad. 48. Apex of head, dorsal view showing anteclypeus; 49. Male terminal abdomen, lateral view; 50. Male, cluster of setae on sternite 7; 51. Female terminal abdomen, lateral view.

Figs. 60-67: 60-64: Hydrometra lineata Eschscholtz; 60. Apex of head, dorsal view showing anteclypeus; 61. Male terminal abdomen, lateral view; 62. Male terminal abdomen, ventral view; 63. Female terminal abdomen, dorsal view; 64. Female terminal abdomen, lateral view. 65-67: Hydrometra longicapitis Torre-Bueno; 65. Apex of head, dorsal view showing anteclypeus; 66. Male terminal abdomen, lateral view; 67. Male terminal abdomen, ventral view.

Figs. 5-9: Hydrometra chaweewanae Sites & Polhemus. 5. Apex of head, dorsal view showing anteclypeus; 6. Male terminal abdomen, ventral view; 7. Male terminal abdomen, lateral view; 8. Female terminal abdomen, dorsal view; 9. Female terminal abdomen, lateral view. Hydrometra okinawana Drake: 10. female terminal abdomen, dorsal view; 11. female terminal abdomen, lateral view.

Figs. 68-75: 68. Hydrometra longicapitis Torre-Bueno, female terminal abdomen, lateral view. 69-73: Hydrometra maidli Hungerford & Evans; 69. Apex of head, dorsal view showing anteclypeus; 70. Male terminal abdomen, lateral view; 71. Male terminal abdomen, ventral view; 72.Female terminal abdomen, dorsal view; 73. Female terminal abdomen, lateral view. 74-75:Hydrometra mindoroensis J. Polhemus; 74. Apex of head, dorsal view showing anteclypeus; 75. Male terminal abdomen, lateral view.