Parker Posey is playing a classic Chekhov character and having a ball

For the rest of us, time seems to fly. But for the preternaturally youthful Posey, it’s as if time has stood still. The fact is Posey is 54 — an utter absurdity if you ask me — but a fact of life that every maturing actor has to deal with.

“Didn’t get to put those cold jade stones on my face this morning,” Posey says, sighing with rehearsal fatigue as she settles into a sofa in the lobby of a theater on West 42nd Street. It’s here that Posey is onstage for the first time in several years, playing Irene, a self-absorbed actress unafraid to quote her rave reviews, in the New Group’s off-Broadway updating of “The Seagull.”

This version of Anton Chekhov’s tragicomedy is called “The Seagull/Woodstock, NY,” directed by Scott Elliott and set in a present-day arty enclave about 90 miles north of Manhattan. Irene is how playwright Thomas Bradshaw re-christens Irina Arkadina, the star whose solipsistic iron will keeps a famous writer in her bed and her son in emotional paralysis. The actresses who have played the part over the past century make for an illustrious roll call: Lynn Fontanne, Eva Le Gallienne, Meryl Streep, Kristin Scott Thomas…

And now, in an evening of Bradshaw’s modern flourishes and pungent takes on the pieties of the theater, Posey adds her name to the roster. She is no doubt the marquee draw and the big reason that the show, which officially opened Tuesday night, has already been extended into April. Still, it may sound like an unlikely switch of lanes for an actress who books passage in offbeat movies so often that publications large and small have crowned her indie royalty.

Then again, she has detoured on occasion to commercial ventures, as she did in diving into the “Superman” franchise in the early 2000s. And she materialized surprisingly on Netflix in 2018 as the dastardly Dr. Smith in the 28-episode remake of “Lost in Space,” the 1960s CBS series with a cult following. (The original Dr. Smith was the wildly theatrical Jonathan Harris.)

“I thank God for that job,” Posey says. “I was obsessed with the original.” Really? Why? “Because it was a family on another planet,” she replies.

Posey speaks in charming, elliptical paragraphs and soothing tones, like the voice of a good therapist. She’s far more thoughtful than some of her flakier roles might indicate. Her current assignment, she says, took her back to her undergraduate days at the State University of New York at Purchase, which has a respected theater program.

As part of it, she studied Chekhov with a teacher she adored who was in acting classes with James Dean. Posey weaves in these biographical tidbits while recalling her initial skepticism about the play she’s now in.

“I was down South helping my mom and I was like, yeah, right, they’re going to be doing this modern adaptation of ‘The Seagull,’” she says, recalling her internal debate. “Like, let me guess: ‘You may show politics, gender politics, this or that,’” she adds, her voice getting nasal and whiny. “Why is everything remade all the time and like, a revival of this, that and the other?”

Then she actually opened the script. “So when I read it, I was like, ‘Ah, I have to do this,’ and then I read it again that night. Right choice. Like, ‘This is really good.’”

It was good for everyone involved, because for Bradshaw, a longtime dramatist who chairs the radio, television and film department at Northwestern University, Posey was akin to a No. 1 draft pick. “She was my first choice of actors for this play,” says the playwright, the author of such raw, highly regarded plays as “Burning” and “The Bereaved.”

“This role was made for her in that the range of emotion that she has is amazing. There’s just such versatility. With Parker, it’s what is she going to say next?” he adds. “There’s another level of comedy because of what Parker has found in that performance.”

If there’s anything that characterizes a Posey performance, it’s the sense of freedom, of simultaneously existing in the real world and one of her own making. It’s why she became such a standout member of filmmaker Christopher Guest’s informal rep company, a troupe that he reassembled again and again in a string of endearingly acute mockumentaries that started with “This Is Spinal Tap” in 1984.

If I had to identify my favorite Posey role in the Guest canon, it would be her abrasive, hyper-neurotic champion dog owner in “Best in Show.” Her freakout scene, as she frantically hunts down a replacement for a lost dog toy, distinguished her even among a group of priceless farceurs, including Fred Willard, Catherine O’Hara, Michael McKean, Eugene Levy, Jane Lynch and Jennifer Coolidge.

She claims not to be naturally improvisational, and early in her training, the discipline of the rehearsal process wasn’t for her, either. “I hated rehearsals,” Posey says of the plays she did at Purchase. “They made me ashamed. You know, I got really embarrassed because I almost got cut from the program. Until I went onstage and they’re like, ‘Oh, we gotta keep her.’ Because I kind of fly around my performance, and then I start to land once I get onstage.”

Posey was born in Baltimore but grew up in Louisiana, with parents she characterizes as highly stage-worthy themselves. “I described my father, which he loved, as a comedian without a venue, because every room he walked into was his audience,” she recalls, adding he was a Faulkner fan who sold cars and “planted wildflowers in front of his car dealership.” “And my mother is very dramatic and funny herself. So I grew up with parents who were stars in my eyes. That to me is very Chekhovian.”

Elliott cast Posey in 2005 in a supporting role in his revival of David Rabe’s “Hurlyburly,” a portrait of drug-ridden Hollywood in the 1980s, in a cast that included Ethan Hawke, Catherine Kellner and Bobby Cannavale.

“I was always a huge fan of hers because under all that comedy was the kind of incredible depth and irony that makes great actors,” Elliott says. “Some of my most memorable rehearsal moments ever are with her, because she takes the direction and turns it into herself. And so you always feel she’s taking the direction and enhancing it.”

In “The Seagull/Woodstock, NY,” Bradshaw makes adventurous leaps with some of Chekhov’s conceits: The playlet that Irina’s/Irene’s son, here played by Nat Wolff, famously stages for his mother and her friends is meant to exemplify the Chekhov character’s rebel cry for “new forms” of theater. Bradshaw’s penchant for exposing audiences to explicit sexual themes and committing other acts of provocation comes into play.

But his adaptation also exhibits great respect for Chekhov’s mastery of character and dramatic development. Posey’s performance in many ways traces the traditional outlines of Irina’s selfishness and vanity. In the actress’s view, the comedic and tragic dimensions of Bradshaw’s version exist harmoniously with Chekhov’s.

“He had a sense of fate, overtaking a way of life,” Posey says of Chekhov. “And his Russian humor seems to me akin to the humor of a Southerner, the kind that lies mostly in character. You know how in ‘Uncle Vanya’ and ‘The Cherry Orchard’ people are always gathered together and talking and talking? No one’s really listening. Yet there’s a great love and understanding that prevails through it, and a knowledge and acceptance of each other’s idiosyncrasies, a tolerance and also an acute enjoyment of the dramatic.”

Posey now is the acting veteran, the role model for cast members including Aleyse Shannon, a recent Carnegie Mellon University graduate who plays Nina, the aspiring actress used and discarded by Irene’s lover, played by Ato Essandoh. Shannon says Posey embraces that responsibility. “She’s a giving and generous person,” Shannon says, “and that includes snacks, thoughts and advice.”

For Posey, what matters is the experience is hitting close to home: “If anyone’s gonna come out of this play and be like, ‘Yeah, I didn’t really like it,’ I don’t care. Because I get to do this. And I get to have this kind of soulful relationship, and it’s bringing me back full circle, not only to my beginnings in drama school, but to the lineage of my family.”

The Seagull/Woodstock, NY, by Thomas Bradshaw, adapted from Anton Chekhov’s “The Seagull.” Directed by Scott Elliott. Through April 9 at Pershing Square Signature Center, 480 W. 42nd St., New York. thenewgroup.org.