italics and normal text in a main plot title

I think other users have answered this, but I found it not so cut and dry, and built off of their input because it gets tricky for long titles like the one in your example.

Here is the cleanest line of code I could conjure for combined italic/normal texts, using a generic plot... let me know how it works for your data (or anyone who reads this and finds it doesn't work with certain graphs, inbox me, I enjoy learning and would rather share than just store it in my noggin)

plot(1:10, main = expression('Mapped territories of different '*italic(C.~austriacus)*' individuals at the Far Gardens coral reef site'))

Now, to line break with expression or like terms that allow italicized or superscript/subscript text (other than simple labels), you can use the atop function to evenly break apart super long labels. One may prefer to use the preview app for final editing and labels, but if you want to stick to R for everything, you can use the following example:

plot(1:10, main = expression(atop('Mapped territories of different '*italic(C.~austriacus),  ' individuals at the Far Gardens coral reef site')))

which gives: plot with long mixed title

Thanks to @42-

Personally I think using paste to construct plotmath expression is "ugly"; This is an alternative the more clearly demonstrates "clean" use of expression:

 plot(rnorm(100),main=expression( italic(p~value) == 0.01 ))

The other reason to use expression is that it will be accepted by Lattice functions whereas the substitute approach will not:

xyplot(1~1,main=substitute( paste(italic('p value'), " = 0.01" )))
#Error in paste(italic("p value"), " = 0.01") : 
#  could not find function "italic"

It would succeed if expression() were used inside the substitute call but it's excess baggage in that instance. I complained to Deepayan Sarkar once and his response was that substitute returns an unevaluated "call" rather than a true 'expression'.

You didn't give any information about your data but if the problem is italics in the title, maybe this code could help:

plot(rnorm(100), main = substitute(paste(italic('p value'), " = 0.01")))

See also this question.