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 Major Groups | Insecta (insects) | Coleoptera (beetles) | Hydrochidae
 

Hydrochidae
Hydrochus

Major Group: Insecta
Order: Coleoptera
Family: Hydrochidae (formerly within Hydrophilidae)
Genus: Hydrochus
This family is represented by a single genus worldwide, Hydrochus.

Descriptive Features:
Adults

  • antennae 7- to 9-segmented with 3- or 4-segmented club
  • 2nd segment of maxillary palpi slender
  • body narrow
  • elytra strongly punctate, exposing less than 2 complete abdominal tergites
  • prothorax without notopleural sutures, ventral portion of the notum, (hypomeron) on each side joined directly to the sternum by notosternal suture
  • pleuron reduced and concealed
  • abdomen with more than 3 ventrites
  • ventrite 1 not divided by hind coxae
  • meso- and metasternae without a continuous common keel
  • basal segment of hind tarsi shorter than 2nd
  • size: 0.5-7.0mm
    Larvae 
  • labrum completely fused to head capsule
  • labial palps 2-segmented
  • apex of mandible unidentate
  • maxilla with stipes longer than wide
  • mesal surface of mandibular base with pubescent lobe
  • gular sutures separate
  • abdominal tergum 8 usually subterminal, forming with segment 9 a spiracular chamber housing enlarged 8th spiracles
  • legs present 
  • size:
  •  

    Hydrochus larva

     

    Hydrochus adult

    Taxonomic Checklist: Species
    Hydrochus abditus
    Watts
    Hydrochus adelaidae Blackburn
    Hydrochus aenigmatis Watts
    Hydrochus aschnakiranae Makhan
    Hydrochus atratus Watts
    Hydrochus australis Motschulsky
    Hydrochus burdekinensis Watts
    Hydrochus cucullatus Watts
    Hydrochus decorus Watts
    Hydrochus euryspleuron Watts
    Hydrochus gitaraiae Makhan
    Hydrochus granicollis Lea
    Hydrochus horni Blackburn
    Hydrochus imamkhani Makhan
    Hydrochus interioris Blackburn
    Hydrochus kunarajahi Makhan
    Hydrochus lateviridis Blackburn
    Hydrochus macroaquilonius Watts
    Hydrochus multicolor Lea
    Hydrochus numerosepunctatus Watts
    Hydrochus obscuroaeneus Fairmaire
    Hydrochus obsoletus Lea
    Hydrochus radjiei Makhan
    Hydrochus simplicicollis Lea
    Hydrochus umbratilis Watts

    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 4

    Functional Feeding Group: shredders (adults), unknown (larvae)

     

    Wakool River on Wakoola, NSW

    Ecology: No Australian larvae are known.
    Instream habitat: Adults of Hydrochidae species are common wherever there is permanent water, living in a wide range of habitats from stagnant pools to gravel edges of major rivers. They are usually found amongst vegetation in gently flowing or still waters.
    Feeding ecology: Hydrochus beetles are herbivores and detritivores feeding on parts of plants, periphyton and detritus.
    Habit: Hydrochus adults canít swim. They crawl around on water plants, submerged wood and other surfaces.
    Life history:

     

    Information Sources: Watts 2002, Williams 1980, Gooderham & Tsyrlin 2002
    Key to Species: Watts 1999 (adults)