Let M(g,+,k)K\documentclass[12pt]{minimal}
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\begin{document}$$\mathcal {M}_{(g,+,k)}^{K}$$\end{document} be the moduli space of orientable Klein surfaces of genus g\documentclass[12pt]{minimal}
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\begin{document}$$g$$\end{document} with k\documentclass[12pt]{minimal}
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\begin{document}$$k$$\end{document} boundary components (see Alling and Greenleaf in Lecture notes in mathematics, vol 219. Springer, Berlin, 1971; Natanzon in Russ Math Surv 45(6):53–108, 1990). The space M(g,+,k)K\documentclass[12pt]{minimal}
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\begin{document}$$\mathcal {M}_{(g,+,k)} ^{K}$$\end{document} has a natural orbifold structure with singular locus B(g,+,k)K\documentclass[12pt]{minimal}
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\begin{document}$$\mathcal {B} _{(g,+,k)}^{K}$$\end{document}. If g>2\documentclass[12pt]{minimal}
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\begin{document}$$g>2$$\end{document} or k>0\documentclass[12pt]{minimal}
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\begin{document}$$k>0$$\end{document} and 2g+k>3\documentclass[12pt]{minimal}
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\begin{document}$$2g+k>3$$\end{document} the set B(g,+,k)K\documentclass[12pt]{minimal}
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\begin{document}$$\mathcal {B} _{(g,+,k)}^{K}$$\end{document} consists of the Klein surfaces admitting non-trivial symmetries and we prove that, in this case, the singular locus is connected.