Rhantus suturalis
In 3 days ~10% in a week ~20%
Rhantus suturalis, commonly known as the supertramp beetle or cosmopolitan diving beetle, is a species of diving beetle (Dytiscidae) with a cosmopolitan distribution. Adult Rhantus suturalis range from 10.5 to 13.0 mm in length. The head is black with a pale anterior margin and a pale marking between the eyes, and the antennae and palps are also pale. The pronotum is pale with a usually well-defined dark mark in the middle. The elytra are pale brown and covered in fine punctures. The sternites of the abdomen are completely black. The legs are brown and often have the metatibiae and metatarsi darker. Males differ from females in the basal tarsomeres of the prolegs and midlegs being weakly dilated, and the protarsal claws being unequal and much shorter than the terminal tarsomere.
In Europe, R. suturalis coexists with the also-common species R. exsoletus, but that species has a vague black posterior margin to the pronotum instead of a central dark mark, and its abdominal sternites are yellow instead of black. In Australia, the only other Rhantus species is R. simulans, which is larger (12.8-13.5 mm) and only found in the country's southwest, unlike the more widespread... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Egmont National Park | 🇳🇿 New Zealand | |
| 2 | Great Otway National Park | 🇦🇺 Australia |
Rare
Under 5% of wildlife watchers report a Cosmopolitan Diving Beetle sighting in Sydney on a given day, based on 16 verified sightings from GBIF citizen-science data. It is the 393rd most-seen of the 742 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Cosmopolitan Diving Beetle in Sydney on a given day, so our monthly data shows no clear season.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Cosmopolitan Diving Beetle sightings with a recorded time, and about half of them come between 6 pm and 6 am: it is most active around dawn and dusk.
Among the best
Of the 7 cities where we can rate Cosmopolitan Diving Beetle sightings, Sydney ranks 6th at under 5%, level with the leaders once rounded. The best odds are in Beijing (China, under 5%), Melbourne (Australia, under 5%) and Seoul (South Korea, under 5%).
GBIF citizen-science records
It is estimated from how often the Cosmopolitan Diving Beetle is recorded against all the insects logged in Sydney (16 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
