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

Psephenidae
Sclerocyphon

Major Group: Insecta
Order: Coleoptera 
Family: Psephenidae
Genus: Sclerocyphon
This family is represented in Australia by a single genus, Sclerocyphon.

Descriptive Features:
Adults

  • antennae 11-segmented without distinct club
  • posterior edge of pronotum distinctly crenulate
  • ventral portion of the notum, (hypomeron) on each side joined directly to the sternum by notosternal
  • suture
  • pleuron reduced and concealed
  • prosternum in front of coxae much longer than intercoxal process
  • body very short and broad, less than 1.5 times as long as wide
  • abdomen with at least 3 connate ventrites
  • elytra exposing less than 2 complete abdominal tergites
  • mesocoxal cavities narrowly separated
  • intercoxal process on ventrite 1 narrowly rounded
  • tarsi simple
  • size: 
    Larvae
  • head completely concealed from above by prothorax
  • antennal length >˝ head width
  • labrum separated from head capsule by complete suture
  • mandibular mola absent
  • body broadly ovate, strongly flattened, disc-like
  • legs 5-segmented, including claws
  • abdominal apex with ventrally hinged operculum, concealing 3 extrusible tufts of fine, slender gills 
  • size: 6.4 - 9.0mm
  •  

    Sclerocyphon maculatus larva

     

    Sclerocyphon adult

    Taxonomic Checklist: Species
    Sclerocyphon aquaticus Lea
    Sclerocyphon aquilonius Davis
    Sclerocyphon basicollis Lea
    Sclerocyphon collaris Fabricius
    Sclerocyphon fuscus Bertrand & Watts
    Sclerocyphon lacustris Davis
    Sclerocyphon maculatus Balckburn
    Sclerocyphon minimus Davis
    Sclerocyphon nitidus Davis
    Sclerocyphon secretus Smith
    Sclerocyphon serratus Lea
    Sclerocyphon striatus Lea
    Sclerocyphon zwicki Davis

    Distribution: E Qld, E NSW, Vic, Tas

    Sensitivity Rating: SIGNAL grade 6

    Functional Feeding Group: scrapers (larvae); terrestrial adults

     

    Mt Wills Creek near Granite Flat, Vic

    Ecology: Instream habitat: Commonly known as ‘water pennies’, Sclerocyphon larvae cling to rocks in strongly flowing or turbulent sections of streams and rivers but they can also survive in well-oxygenated stretches of stagnant water. The larvae are usually absent from loosely packed substrates, sandy substrates and highly enriched or silted streams. Adults are terrestrial and cryptic, usually remaining hidden in leaf and twig litter, high-water leaf packs or debris and riparian vegetation on stream banks.
    Feeding ecology: Larvae are grazers and scrapers feeding on the biofilm associated with stream rocks and wood. No information is available on the feeding habits of adults.
    Habit: The larvae avoid daylight by clinging to the underside of stones in streams. In dim light and at night they crawl to the upper surfaces to graze. Larvae breathe dissolved oxygen in the water through a tuft of anal gills and they can breathe atmospheric oxygen when out of water. Adults have been observed flying above streams on hot days.
    Life history: Larval development seems to incorporate 5-6 instars, with little development over winter months. Temperature seems to be the main factor influencing larval growth and overall duration of the lifecycle. In Tasmania, the life cycle completes in 24 months whereas in Queensland the life cycle completes in only 12 months. Final instar larvae leave the water in spring and remain hidden for several weeks under rocks, logs or litter on the bank before pupating. There is a pre-pupal phase and pupation occurs within the last larval skin. Pupae often cluster in one spot with the pupal stage lasting from two to three weeks. Adults live up to three weeks within terrestrial litter where they mate. Females return to the water to lay their eggs, which are virtually invisible to the naked eye, in a single layer under submerged rocks. The larval stage is present in streams and rivers throughout the year (22 months from a 24 month cycle) while the adult and pupal stages are short lived for a few weeks in spring and summer. The egg phase is also very short.

     

    Information Sources: Davis 1998, Davis 1986, Lawrence & Britton 1991, Calder 1999c, Williams 1980, Gooderham & Tsyrlin 2002
    Key to Species: Davis 1998 (larvae) 

     

     

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