The situation is a bit more complicated than most. While employer's typically have the discretion to pay employees at any rate they choose, if the employer has published pay scales for certain jobs, then employees should normally be paid within that scale or the employer risks a breach of implied contract claim typically.
In addition, it does sound as though there is something odd in this situation, but it is not clear what it is, since you are paid significantly less than the other lowest paid employee in the department.
Normally, to prove a claim of gender discrimination you must present evidence that similarly situated employees (ones who perform the same or virtually the same job and are as qualified or at least less qualified) who are male are being paid more than you are.
Here, it does not appear anyone has the same job as you do, or if there is one who has a job that is similar enough, they may be more qualified.
Without some circumstantial evidence of discrimination then, your claim would normally fail.
You could file a complaint with the state fair employment and housing commission, but they are unlikely to investigate on their own. Because of that, I would try first to consult further with a local employment law attorney to see whether there are any facts that may support a discrimination claim.
If not, then an implied contract claim would normally be your only other option to pursue any recourse against the employer.
I hope you found my answer helpful, even if the law is not in your favor; please click on the GREEN ACCEPT button above for my answer. This is necessary for me to be paid for my work and so that I can get credit for assisting you. Your question will not close, and you will still have the opportunity to follow-up if needed. Leaving a bonus and positive feedback is not required, but doing so is certainly appreciated!
If you have additional questions, please keep in mind that I do not know what you already know or don't know, or with what you need help, unless you tell me. Please consider that I am answering the question or question that is posed in your posting based upon my reading of your post and sometimes misunderstandings can occur. If I did not answer the question you thought you were asking, please respond with the specific question you wanted answered.
Also remember, sometimes the law does not support what we want it to support, but that is not the fault of the person answering the question, so please be courteous. Thank you.