Tim Mongi was the illustrator of the Handbook of Exobiology. (PIC: "Disengage")
The prop book was created by scenic artist Geoffrey Mandel, and the creature illustrations are by Jim Martin. The cover of the book and the two pages seen in "Strange New World" used to be showcased on Mandel's homepage. [1](X)
The cover of the book, containing the illustrator credit, was first visible onscreen in "Disengage".