Form Holds True Through Season : Prep basketball: Playoffs begin tonight with the preseason favorites, the Mater Dei boys and the Peninsula girls, ranked No. 1.

A high school basketball season of few surprises begins its descent tonight with the first-round of the Southern Section playoffs.

The Santa Ana Mater Dei boys and Palos Verdes Peninsula girls, tabbed preseason favorites, enter the playoffs as the No. 1-ranked teams in The Times’ polls. Both have received national recognition as well, with Mater Dei (26-1) No. 18 and Peninsula (24-0) No. 1 in USA Today.

Mater Dei, 278-25 the past 11 seasons, has won 12 consecutive games since a 69-50 loss to Oak Hill Academy (Mouth of Wilson, Va.) in the championship of the Above the Rim tournament at San Diego State on New Year’s eve. The Monarchs claimed their ninth Angelus League title in the past 10 years.

“I don’t fear anybody, but I respect any opponent,” said Gary McKnight, Mater Dei’s coach.

The Monarchs, led by senior Reggie Geary, rely on balance. McKnight often uses nine players in the first half.

Mater Dei enters the tournament as the top-seeded team in Division I-A, the second most elite of the 10 divisions. The Monarchs were in the same position last season, but were upset by Huntington Beach Marina, 64-55, in the semifinals.

Their main competition figures to be second-seeded Riverside North (23-2), which has won 18 consecutive games. The Huskies’ only losses were to Capistrano Valley and Lynwood, the top-seeded teams in I-AA.

No one figures to challenge the Peninsula girls, the No. 1-seeded team in II-AA.

The Panthers defeated nearly every top team in the Southland this season, including Thousand Oaks and Brea-Olinda. They won their eight Bay League games by an average score of 80-24.

Peninsula, a new school the result of the consolidation of Palos Verdes, Miraleste and Rolling Hills highs, features an experienced lineup. The four senior starters--Jeffra Gausepohl, Kristen Mulligan, Raquel Alotis and Monique Morehouse--have all received scholarships to Division I schools. Sophomore Mimi McKinney was a preseason All-American.

To get ready for the playoffs, Peninsula scrimmaged the school’s boys’ team this week.

“It gets kind of boring and old pounding on each other every day,” said Wendall Yoshida, Peninsula’s coach. “But it’s given us time to work and prepare.”

The playoffs culminate with championship games March 6-7.

FAVORITES: The boys’ field is well balanced in every division except IV-AA, where defending champion Santa Clara (21-3) should have little trouble repeating. The girls’ field is less competitive. Thousand Oaks (I-A), Brea-Olinda (III-AA) and West Covina South Hills (III-A) should breeze through.

TOUGH BATTLES: The most interesting division is boys’ II-AA, with Glendora (26-0), Artesia (21-3), Riverside La Sierra (23-2) and Pasadena Muir (18-8), among others, ready to battle. Tustin (19-7) is the defending champion, and Artesia won the II-A title last year. Glendora is led by Cameron Murray, younger brother of UCLA’s Tracy Murray, and Artesia is led by Charles O’Bannon, whose older brother, Ed O’Bannon, also plays at UCLA.

GRUDGE MATCH: The biggest rivalry is in girls’ IV-AA between Los Padres League foes Santa Ynez (20-2) and Morro Bay (19-3). Morro Bay was top-seeded in the division last year and beat Santz Ynez, 56-34, in the title game. Santa Ynez is top-seeded this year and defeated Morro Bay in three of four regular-season meetings.

WON’T QUIT: State sprint champion Marion Jones, who suffered a broken wrist and dislocated jaw in a Thousand Oaks basketball game Jan. 9, is working out with the Lancers this week and expects to be back in action for the later part of the tournament if the school is still alive.