Try:

RewriteRule ^/services/([a-zA-Z0-9\-]*)$ /services.php?id=$1 [L]

The dash is a reserved character and usually needs to be escaped with a backslash.

You also still need to have the parentheses. That is how mod_rewrite knows which part of the original string to use to replace the $1.

Also, you need to tell mod_rewrite how many characters to match. The brackets will only match a single character that matches the range of possible characters listed. Adding the asterisk after the closing bracket tells it to match as many characters as there are.

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