Retail’s 16.4 percent April downfall isn’t the biggest shocker in the latest monthly sales report. Though last month’s dismal performance outgunned March’s 8.3 percent tumble, specialty stores saw unprecedented carnage with an 89.3 percent year-on-year decline. Specialty stores sales for apparel and accessories in April generated just $2.37 billion, down precipitously from $22.25 billion a…