[rebolek]

In Czech (but may be true for other Slavic languages, at least western ones):

* Josef - male form

* Josefa - female form

* Josefka - diminutive female form

so Iosevka to me looks like English spelling of Josefka

If you're curious, male diminutive forms of Josef are: Josífek, Jožin, Jožka, Pepa, Pepík and about 100 others.