Determine if a gene is mitochondrial or not I need to determine whether a gene is mitochondrial or not for C. Elegans automatically from its name by running a regular expression on a dozen of thousands of gene names. Currently I am having gene symbols like: 

clec-190, clec-189, 21ur-8912, nduo-1, 21ur-6539, 21ur-13096, nduo-6, 21ur-14241, ndfl-4


I tried running grepl("^mt-", symbols) and it found nothing. I am sure that there are some mitochondrial genes just from their descriptions. I would assume that first I need to convert gene symbols to some other symbols to do that but I am not sure here.

Basically, I am trying to do it in a similar way to the tutorial of single cell RNAseq.
You can't determine if a gene is mitochondrial purely from its name. The simplest route would be to use the wormbase biomart and either download the gene names and their associated chromosomes or use the biomaRt package from bioconductor to do the same thing. You can upload a list of the genes you're interested in querying in either case (or just download all of them, and filter).

From your list, only nduo-1, nduo-6, and ndfl-4 are mitochondrial.