Dear Harry, et al.
I goofed on words ending in -x. They are feminine only about 60% of the time. I ran queries on my database of generic names for Western Atlantic mollusks, but apparently I ran that one incorrectly. Regarding Troschelvindex, it is indeed masculine. In Latin, "vindex" is common. By ICZN rules, words for which the gender cannot be determined or ones which are sometimes but not always masculine are treated as masculine for the purposes of zoological nomenclature.
Gary