UPDATE 1-Zalando says sales up since Easter helped by Beyonce

(Corrects spelling of name, paragraph 6)

* Expects Q1 revenue 788-801 mln vs consensus for 822 mln

* Reiterates 2016 revenue, EBIT margin targets

* Says sales up since Easter helped by new Beyonce label

BERLIN, April 19 (Reuters) - Zalando (Swiss: OXZALG.SW - news) reported slower first-quarter sales growth after a blistering 2015, but Europe's biggest dedicated online fashion retailer said sales had accelerated since the Easter holidays in late March and reiterated its annual targets.

Fashion retailers such as H&M and Next (Other OTC: NXGPF - news) have reported a weak start to 2016 due to an earlier Easter than last year and a late start to spring, although Zalando's closest rival ASOS (LSE: ASC.L - news) is still growing fast.

Zalando said on Tuesday that quarterly revenue rose by between 22.5 and 24.5 percent to 788 to 801 million euros, missing average analyst forecasts for 822 million euros ($930.92 million), and down from 28.5 percent growth in the first quarter of 2015.

Zalando shares fell more than 5 percent following the results before paring some of their losses to stand down 3.8 percent at 0721 GMT.

"Investors may be a bit disappointed by the weaker-than-expected first-quarter sales growth, but we expect this will be somewhat offset by management's commentary that sales have picked up since Easter," said Bernstein analyst Jamie Merriman.

Management board member Rubin Ritter said Easter was usually slower as people were on holiday, but sales had picked up again since then, helped by heavy marketing for the launch of a new sports label, Ivy Park, co-founded by pop star Beyonce.

"We are positive for the season but you have to take the weeks and seasonality as it comes," he told Reuters.

Adjusted earnings before interest and tax (EBIT) come to between 12 and 28 million euros, compared with consensus for 21.6 million, while the adjusted EBIT margin should be 1.5 to 3.5 percent. Zalando reports full quarterly figures on May 12.

Zalando reiterated full-year guidance for revenue growth at the upper end of a 20 to 25 percent range and an adjusted EBIT margin of 3.0 to 4.5 percent.

Launched in Berlin in 2008, Zalando serves customers in 15 European markets with more than 1,500 brands, including big names such as Gap, Banana Republic and Topshop.

($1 = 0.8830 euros) (Reporting by Emma Thomasson; Editing by Maria Sheahan)