Sternopriscus wattsi
Ordo: Coleoptera
Familia: Dytiscidae
Genus: Sternopriscus
Name
Sternopriscus wattsi Pederzani, 1999
Type locality
Pond, Della Franca Farm near Pemberton, southwestern Australia.
Type material
Holotype: male, "Australia (WA), Pemberton, pond, Della Franca Farm, 3.12.1998, Pederzani" (SAMA). Paratypes: 5 exs., same data as holotype (CFP, CLH, SAMA); 2 exs., "Australia (WA), creeks across Vasse Hwy, 3.12.1998, Pederzani leg." (CFP, SAMA); 4 exs., " Australia (WA), Nannup, roadside creek, 1.12.1998, Pederzani leg." (CFP).
DNA Sequences
European Nucleotide Archive (ENA)
Description
Measurements: Males: TL = 2.95 - 3.1 mm, TL-H = 2.76 - 2.90 mm; width = 1.60 - 1.68 mm. Females: TL = 2.85 - 2.95 mm, TL-H = 2.70 - 2.85 mm; width = 1.55 - 1.65 mm.
Colour: Head black with two testaceous spots at the anterior margin; pronotum black, widely testaceous at sides, with two testaceous spots occasionally connected in midline, the posterior spot sometimes absent. Elytron dark brown to black, with diffuse testaceous mottling, sometimes absent on disc; ventral surface dark brown to black, appendages and apical sternites paler, antenna with segments 5 - 7 and 11 darker, tibiae and tarsal segments apically darkened, hind legs particularly so.
Sculpture: Reticulate, strongly and densely rugose-punctate, punctures weaker but well marked on head. Pronotal plicae well marked reaching about half way along pronotum, well-marked transverse depression between them. Elytral margin weakly serrate towards apex. Prothoracic process narrow, sides parallel, not reaching metasternum. Midline of metasternum weakly raised in extreme front; metacoxal lines strongly raised, weakly diverging forward.
Male: Larger. Antennae simple, not expanded. Pro- and mesotarsi moderately dilated. Protibia moderately expanded with a slight excavation near base on inside. Mesotibia slightly expanded and curved. Metacoxal processes very long, projecting backward, jointly fork- shaped, almost attaining the sutural line between third and fourth visible sternites. Median lobe of aedeagus apically swollen, flower-shaped, tip broad in lateral view.
Female: Smaller. Appendages simple, metacoxal processes projecting backwards but much shorter than in the male.
Affinities
Sternopriscus wattsi is unique among Sternopriscus in having the metacoxal processes projecting backward, strongly so in the males, covering the interlaminar bridge. The simple male antennae distinguish them from other western Australian species but females can be easily confused with S. browni and can only be separated by the form of the metacoxal processes.
Habitat
The species inhabits either lentic sites such as well vegetated small farm dams and ponds beside larger streams or lotic sites such as small pools in seasonal woodland streams. At Byenup Lagoon all specimens were collected in shallow water (up to 10 cm) of a freshwater Melaleuca rhaphophylla sedge swamp, rich in aquatic vegetation (e.g. Baumea articulata, Montia australasica, Utricularia sp.) and mats of floating grasses. The area is surrounded by Jarrah/Marri woodland. It is sympatric and sometimes syntopic with S. browni, S. marginatus, S. minimus, S. multimaculatus and S. storeyi.
Distribution
Southwestern coastal Australia, Western Australia. South and southwest of a line from Perth to Manjimup
References
- Hendrich, L.; Watts, C.H.S. 2004: Taxonomic revision of the Australian genus Sternopriscus Sharp, 1882 (Coleoptera: Dytiscidae, Hydroporinae). Koleopterologische Rundschau, 74: 75–142.
