Of course, R could also be used to create more traditional atlas dot maps; coastal outlines of Britain are freely available in more than one R package, and occurrence data relating to the UK grid could be manipulated in R to centre on monads, tetrads or hectads. External tools could also be used to do this before loading the data into R, e.g. see here.
The result is below. I'd be grateful to hear from anyone who can suggest any refinements to my code, or the general way in which I've gone about this.
|Polypogon viridis in Sheffield, UK, 2013|