184 



Usinger: Hemiptera 



HYDROMETRIDAE 



MICROVELIINAE 



VEUIDAE 



MESOVELIIOAE 



Disapp.aranc. of Madiar 

 V.ntrol Motothoracic 

 Sent Gland (Tr.nd 2) 



LIMNOBATODES 

 Fusion of Thoracic 

 Sent Glands (T-2) 



Lots of Median 



Longitudinal Sulcus 



on Hood 



I 

 Oisoppooronc* of 



Oc.lli (Tr.nd 5) 

 ■ 



R.turn of 

 HEBRIDAE H.t. rocl.pt> 



to th. Shor. Tort 



Forrr 

 Tori 



PTILOMERIM 

 R.duction 

 of Tarsal 



Segmentation 

 to 2-1-1 



Armature of 

 Middle Femora 



Reduct 



y 



HALOBATINAE 



I 



Bugs Take to the 

 Surface of the Sea 



f 



Shortening and 



Broadening of 



Body 



ition of 

 il Cleft 



nation of 

 Segmentation 



of Tarsal 

 Segmentation 

 to 2-2-2 



I 



Disappearance of 

 Lateral Channels 

 of Scent Glands 



■ 

 BRACHYMETRA 



| HETEROCLEPTES 

 Increase in Number 

 of Antennol Segments 1 



(4 to 5) Disappearance of 

 Development of I Lateral Scent Gland 



Ovipositor | Channels (Trend 2) 



Reduction of \ 



Venation (1 Cell) I 



I Elongation of Head, 



Reduction of Rostral 

 Segmentation 

 Reduction of Bugs~Colonise 



Tarsal < Segmentation Sn#It#r#d R #flion 

 Close to Shore 

 Bugs take to 

 Floating Vegetation 



CYLINDROSTETHUS 



f 



Modification of 

 Legs for Spec 

 Locomotion 

 (Rowing) 

 Movement of Tarsal^ 

 Claws from an Apical to 

 a Preapical Position 

 (Trend 4) 



TRECHUS 



■egm< 



MACROVELIIDAE 



Bugs Leave Water 

 and Return to Land 



I EOTR 



Modification 

 of Scutellum 



Loss of 

 Ocelli Reduction of Tarsal 

 (Tr«nd_5L^^ Segmentation 

 to 1-2-2 



Metothoracic Scent 

 HEBROVELIIDAE Glands_ Fuse 



/ 



Bugs Inhabit Damp 

 Moss Near Water 



Lateral Channels of Scent Glands 



Persist. Two openings of Ventral 



Metathoracic Scent Gland. 



OCfcTLLOVEL/A 



Loss of Larval Abdominal 

 Scent Glands (Trend 3) 



Metathorocic Scent Glands Move 



Slowly from Lateral to Ventral 



Position (Trend 2) 



Posterior Elongation of Pronotum 



in Macropterous Forms, to Cover 



Scutellum and Pronotum Thickened. 



(Trend 1) 



Apterous Forms Developed 



Lateral Channels 



of Scent Glands 



Disappear (Trend 2) 



SALDIDAE 



Bugs Take to the Surface Filn 



Ancestral Surface Bugs 

 Littoral Forms. 



Ocelli Present, Clows Apical, Symmetrical. Abdominal 

 Scent Glands Present. Metathoracic Scent Glands 

 Lateral. Head with Median Longitudinal Furrow and 

 3 Pairs of Trichobothria. Tarsal Segments 3—3—3. 

 Hemelytra with 6 Closed Cells. Pronotum Truncate 

 Posteriorly Exposing Scutellum. 



PROTO-SALDIDAE 



I 



PROTO-HETEROPTERA 

 T.r,.. trial 



Fig. 7:2. Probable evolutionary lines of surface 

 bugs (China, 1955). 



The California fauna is roughly comparable in 

 number of species and percentage representation of 

 families to other parts of the world. Table 7:1 shows 

 a detailed comparison with the best known and most 

 recently catalogued fauna, that of the British Isles 

 (Kloet and Hincks, 1945). California has roughly one- 

 third more species than Britain. The percentage 

 composition, however, is quite different, the Corixidae 

 being significantly more numerous in species in 

 Britain and the Notonectidae, Naucoridae, and Ve- 

 liidae being less numerous. One species each of 

 Pleidae and Aepophilidae occur in Britain but are 



lacking in California, and the families Belostomatidae, 

 Gelastocoridae, Ochteridae, and Macroveliidae, present 

 in California, do not occur in the British Isles. 



Jaczewski (1937) has carried this type of analysis 

 still further, and from his tables it is evident that 

 the California fauna compares favorably with those 

 of Poland, Germany, Sweden, Holland, France, and 

 New York, being larger than any of these both in 

 number of species and in area. However, the per- 

 centage of Corixidae is about half that of each of 

 the above faunas. The fauna of the Malay Archipelago 

 is larger than that of California whereas the Australian 



