Sternopriscus williamsi
Ordo: Coleoptera
Familia: Dytiscidae
Genus: Sternopriscus
Name
Sternopriscus williamsi Hendrich & Watts, 2007
Type locality
Between lakes Augusta and Ada, northwestern Tasmania, Australia.
Type material
Holotype: male, "Australia/NW-Tasmania between lakes Augusta and Ada, Feb. 1963 W.D. Williams leg." (SAMA). - Paratypes, 1 male and 1 female, same data as holotype (CLH, CPZ). 44 exs., "TAS Rocky Lagoon 2 k E Lake Ada 41 52 52 146 29 43 7/10/02 C.H.S. Watts" (SAMA); 320 exs., "Australia: C TAS, CPCA, 500 m E Lake Ada, pools, 1154m, 14.XII.2006, 41.52.575S 146.28.432E, L. & E. Hendrich (TAS 149)" (BMNH, CLH, NMW, ZSM).
DNA Sequences
European Nucleotide Archive (ENA)
Description
Measurements: Holotype, male: TL = 2.5 mm, TL-H = 2.2 mm; width = 1.2 mm. Paratypes, male: TL = 2.4 – 2,6 mm, TL-H = 2.1 – 2.3 mm; width = 1.2 – 1.3 mm; female: TL = 2.3 – 2.6 mm, TL - H = 2.1 – 2.4 mm; width = 1.1 – 1.3 mm.
Colour. A very variable species. Most specimens dark red-brown, head and disc of pronotum almost blackish. In some specimens sides of pronotum paler and elytra with moderately distinct lighter mottling, particularly at base and sides.
Sculpture. Strongly reticulate. Elytron margin very weakly serrated towards apex. Pronotum and elytron covered with rather long setae. Head with relatively sparse rather shallow punctures, pronotum covered with strong, evenly placed punctures very rugose at sides, rest of body strongly rugose-punctate. Pronotal plicae well marked, reaching a little over half way along pronotum, joined by a shallow, narrow depression. Prothoracic process robust, subparallel, strongly rugose-punctate, not reaching metasternum. Metacoxal lines strongly raised, relatively close, diverging slightly towards front.
Male. Antennal segments 8-10 slightly expanded, apically elongate, about same width as segment 10 and about twice as long. Protarsus strongly expanded; profemur expanded with basal ridge on inside near base strongly developed; protibia moderately expanded, curved, with slight excavation near base on inside. Basal three segments of mesotarsus moderately expanded. Median lobe of aedeagus broad, very thin epically, tip bilobed.
Female. Almost same size as males. Antenna shorter, robust, middle segments not expanded, apical slightly elongate, about same width as segment 10 and about 1½ as long. Protarsus strongly expanded, basal segments of mesotarsus moderately expanded.
Affinities
A member of the S. meadfootii complex. Within the complex S. williamsi is separated from all other species by its relatively simple male antennae, except S. mundanus. In its dark colour and elongate shape, rugose sculpture it most resembles S. montanus, but readily distinguished by its relatively simple male antennae in contrast to S. montanus with its strongly expanded middle antennal segments in the male. In addition, the female can also be easily recognised by its simple antennae and strongly expanded pro- and mesotarsi. In the key to Sternopriscus species given by Hendrich & Watts (2004) it will run to S. mundanus. It can be separated from this species by: sides of pronotum widely and clearly testaceous (S. mundanus); pronotum (and often rest of dorsal surface) black or dark chocolate-brown, at most with narrow region diffusely lighter at sides (S. williamsi).
Habitat
At Lake Ada the species was collected in open, moderately deep (to 20 cm) tarns, in places with some sparse aquatic vegetation on a flat peaty bottom (Fig. 3), in a region of open alpine sedge/heath land.
Etymology
Dedicated to the late Australian limnologist W.D. Williams (Adelaide, Australia) who collected part of the type material.
Distribution
Tasmania. Only known from the type locality (Fig. 2). Collected between two alpine lakes (above 1000 m) of the eastern part of the Central Plateau Conservation Area of Tasmania.
Images
|
References
- Hendrich, L.; Watts, C.H.S. 2007: Update of Australian Sternopriscus Sharp, 1882 with description of three new species (Coleoptera: Dytiscidae, Hydroporinae). Koleopterologische Rundschau, 77: 49–59.
