Adding new species to dynamic named lists

Try this:

Sub AddSpecies()
Dim wsADD As Worksheet, wsSPEC As Worksheet

Set wsADD = Sheets("Add_Species")
Set wsSPEC = Sheets("Species")

    If WorksheetFunction.CountA(wsADD.Range("C7:F7")) < 4 Then      'make sure all fields are filled
        MsgBox "All fields must be filled in"
        Exit Sub
    End If

    wsADD.Range("C7:F7").Copy                                       'copy new data to REF sheet
    Sheets("Reference").Range("G" & Rows.Count).End(xlUp).Offset(1).PasteSpecial xlPasteValues
                                                                    'add species to common name list
    Set CommonFIND = wsSPEC.Rows(1).Find(wsADD.Range("E7"), LookIn:=xlValues, LookAt:=xlWhole)
    CommonFIND.End(xlDown).Offset(1).Value = wsADD.Range("D7").Value

    wsADD.Range("C7:F7").ClearContents                              'clear the table

    Sheets("Input1").Activate
    ThisWorkbook.Save
    MsgBox "New Species Added"

End Sub