"The bikinis here are so tiny, the idea of wearing one in a show, with the lights and the cameras and everyone looking at you, it's super scary," she said.
Carol Marra, a 25-year-old transgender who is also with Mattos' modeling agency, became a cause celebre at Rio fashion week last May when she sported swimwear on the runway. The 5-foot-11 brunette model, who has had breast implants and the tip of her nose fixed, said she plans to undergo sex-reassignment surgery next month.
A journalist by training, Marra worked for a local TV station before her trademark androgynous style launched her career as a fashion stylist.
"The photographers I worked with were always saying, 'You should model, let me take pictures of you.' But I was really shy and I didn't want to be in front of the camera," said Marra, who also hails from Minas Gerais state. Eventually, she agreed to pose for a friend, she said, and those photos led to other photos and to a modeling career that took off about a year and a half ago.
Since then, she's enjoyed remarkable success, doing a whirlwind of commercial work, as well as her much-hyped appearances at Fashion Rio and Sao Paulo fashion week and a nearly nude cover of men's magazine Trip.
Still, being a transgender remains a double-edged sword in Brazil, said Marra. She's been rejected for jobs because clients were worried that she would send the "wrong message" to customers. Scenes she shot for a pharmacy commercial ended up on the editing room floor when the client panicked at the last minute.
The head of a gay, lesbian and transgender advocacy group, Toni Reis, cautioned that success on the runway doesn't mean transgenders and transsexuals are out of the woods yet.
Despite its international reputation as a haven for transgendered people, 114 trans people have been killed in Brazil this year to date. Brazil and Thailand are reputed to have among the world's largest trans populations.
"These were people killed in terrible ways, stabbed 40 times, their heads split open with a machete," said Reis. "They were not victims of the sort of everyday violence we see here in Brazil, like armed robberies and such, but rather the victims of homophobia.
"Within the gay community," he said, "transsexuals continue to be the most vulnerable group, by far."
Nonetheless, the gay rights movement has made major headway in Brazil, the world's largest Catholic country. A 2011 decision by the nation's high court to recognize same-sex civil unions was hailed as a watershed, although it stopped short of legalizing gay marriage.
In a major coup for transgendered people, nearly all Brazil's 26 states have so-called "common name" laws on the books, requiring school teachers to call trans students by the names they go by, as opposed to their birth names, activists said.
Transgenders are even entering the mainstream media and culture.
Last year, the top-rated reality show Big Brother Brazil featured its first transgender contestant and a transgender also competed late last month in the second annual Miss Bumbum competition, a beauty contest that focuses exclusively on Brazil's most obsessed-over part of the female anatomy.
There's even talk that TV Globo, Brazil's No. 1 broadcaster, might soon include a transgender character in one of its prime-time soap operas.
Trans-model Marra said she's been thinking about taking acting classes, just in case the opportunity should arise.
"You know fashion is fickle, what's in one day is out the next," said Marra. "I hope trans models are not just a trend, to be dropped like a hot potato next season."