The John and Bo Derek travesty of "Tarzan, the Ape Man," now at area theaters, figured to be an extended Amateur Night in the jungle. The slightest familiarity with his pathetic directing and her teensy-weensy acting range would have precluded any other possibility.

Unfortunately, all too many paying customers will remember being suckered into the Derek remake of "Tarzan," which shortchanges every feature susceptible moviegoers must assume they'll find: tongue-in-cheek romance, exotic high adventure and generous scrutiny of Bo in the buff. Denying people the forms of amusement, notably erotic amusement, that the publicity suggests, Derek exposes a truly dangerous ineptitude.

There's no excuse for any version of "Tarzan" to be a stupefying bore. Derek not only devalues one of MGM's vintage properties but also reduces his meal ticket from instant bombshell to instant dud. Derek affects a very jocular tone as the picture begins: The sound of Tarzan's yell is substituted for the roar of MGM's Leo, and we're shown an elaborate title card, illustrated with a fleshy caricature of Bo for Svengali Productions, the Dereks' film company. By the time the audiences files out in disillusioned silence, it's apparent that Derek is more of a reverse Svengali with nothing at all to feel smug about.

The gimmick of this "Tarzan" is the casting of Bo, the pin-up sensation of Blake Edwards' "10," in the role of Jane. Although Derek flatters himself that he's orchestrating a soft core romantic idyll, the tease produces a slow burn. His approach to the mating of Tarzan and Jane is so revoltingly coy and his filmmaking style so inertly picturesque, like an arthritic imitation of "The Black Stallion," that the movis is no more titillating than two hours of patty-cake.

The early Tarzan films with Johnny Weissmuller and Maureen O'Sullivan were far sexier, not to mention more charming and action-packed. Their first love scene in the 1932 "Tarzan, the Ape Man" still radiates an erotic luster that puts the Derek version to shame. No stirring affinities develop between handsome stiffs like Bo Derek and Miles O'Keefe, the compatibly inexpressive side of beefcake cast as her nonspeaking, uncommanding Tarzan.

The director allows the production to be dominated by Richard Harris in a hambone performance as Jane's father, a great white hunter named James Parker. As a result, the heroine seems to degenerate from a daring, self-reliant type into a whiney, pea-brained daddy's girl.

The opening sequences depict Jane traveling alone in the tropics, where she charters a boat and overtakes the expedition led by her father, suppoledly seeking an elephants' graveyard in West Africa in 1910, although the actual location of the film, Sri Lanka, tends to invalidate the African illusion right off the bat. Parker has evidently been a lifelong cad, abandoning Jane and her mother when the girl was still an infant. The mother has died back in England, leaving Jane with a fortune and a perculiarly breathy, monotonous American accent.

The initial suggestion that Jane has a mind of her own and the gumption to look after herself seems to vanish after her reunion with hypocritical old dad, who hands her a line of malarkey about being secretly devoted to her welfare, 20 years of neglect notwithstanding. "How much do you hate me?" Harris coos. "I think . . . very, very, much," Bo answers primly. "Hate is a very, very strong emotion," he warns. "It can drain one." With a knowing sigh, Bo replies, "I know," and from that moment on father and daughter become ineffable soulmates.

When Tarzan finally makes his entrance, it's as a molester rather than a rescuer. Bo goes skinny-dipping in the ocean and can't retrieve her frock because a lion has trotted dowsn to the beach to gawk at her. This standoff is interrupted by the appearance of O'Keefe, who runs into the surf and attempts to hoist Bo over his shoulder. "No, no, no," she whimpers, although it's difficult to see why. You'd expect a specimen like her to be fascinated by a specimen like O'Keefe and begin exchanging information about dieting, exercise and general physical fitness. A more appropriate response would be, "Where do you work out?"

At any rate, the impulsive intruder is frightened off by the untimely arrival of papa, who commences ranting and raving along the following wacky line: "Do you know what he wants ? Do you know what this ape wants ? This ape son of a bitch wants you ! Ape or man, I'm going to stuff him and hang him on the wall of my club!" Sure, sure; now go take a cold shower, Harris.

The second abduction proves successful, about Jane frightens Tarzan away by belatedly pulling a gun on him. Not sure if she's done the right thing, Bo makes a little fist and daintily pounds on a tree limb once, twice. Ouch, ouch. Tarzan finally gets a chance to act as Tarzan should when Jane is embraced by a python. Showing his unerring instinct for the ineffective, Derek depicts the ensuing struggle in slowmotion, overlapping disolves that cancel out any potential excitement.

The courtship of Tarzan and Jane is long overdue, but Derek approaches the subject in a mood of plodding mock-innocence. O'Keefe slowly stalks Bo, who keeps backing off gingerly and acting like a bashful schoolgirl, biting her fingers through a dimply smirk. Talking to herself, the heroine emits a gush that would have made Gidget fwow up: "Well, I'm still a virgin, but now I don't know whether that's gooood or baaaaad. Gosh, if the girls back home could see me now!" Bottoming out, she tells the bewildered ape man, "Do you know, you're more beautiful than any girl I know?"

John Derek has such a childish imagination that Tarzan and Jane shrink to the dimension of vaguely lewd toys. It's as if one were watching an animated movie in which Ken and Barbie dolls played Tarzan and Jane.

The "R" rating is to be applauded, not because there's any hot stuff worth savoring but because it should spare thousands of children unspeakable boredom. The most suggestive tadbits appear under the closing credits: a bare-breasted Bo, O'Keefe and the orangutan C. J. (better known as Clint Eastwood's sidekick Clyde) wrestle playfully in the sand, evoking fleeting, ludicrous hints of three-cornered foreplay. It's a dopey parting tease, and the filmmakers are obviously being deceitful when they pretend that nothing lewd was ever intended. The unforgivable aspect, as far I'm concerned, is the obvious imitation of the closing scenes of "The Black Stallion," in which the boy and the horse were recalled at play on the island. Evidently, no degrading twist is beneath John Derek. A lesser wretch might have been satisfied with trashing "Tarzan" alone.