Just lump it in with the rest. The IRS doesn't need to see a breakdown by 1099 on your tax return. As long as the total income your report on the Gross Receipts line is equal to or greater than the 1099s it got for your SSN they won't need to know the details.
You should have been planning to report that income whether you got a 1099 or not. Employers are required to issue a 1099 if they pay you more than $600. They are allowed to issue one for any amount even if they don't have to. You are required to report all income even if you don't get one.
One thing that can bite people unexpectedly is if they don't get a 1099 so they leave off that company's income and file their return without it. Then the company files the 1099s after the deadline. I had that happen to a client once. She thought she was "working under the table" (i.e., colluding with the employer for both of them to cheat on their taxes) and wouldn't get a 1099 so didn't bother telling me about the money she made working as a receptionist for a small company. then the company did their own tax return and found out they couldn't deduct what they paid her unless they 1099d her. so she got a 1099 a year after she should have and had to pay the taxes on it and penalties for not reporting it when she made it. It was over $20,000. I think the tax bill with the penalties and interest added was about $10,000 if I remember right.
We are all required to pay taxes on our income regardless of whether it was reported or not. I had another client who never got a W-2. We had to request the W-2, then when it didn't come, we had to report to the IRS that we requested the W-2, and when the IRS's contact didn't shake them loose of one, we had to estimate what the earnings and withholding should have been and fill out one ourselves and report that. No idea what happened to the company (who went out of business) but my client was legal and clear on the matter. If he hadn't reported it and three years later the company finally issued all those back W-2s my client would have been the one in trouble for tax evasion.
Time to build a bigger bridge.