The species that invade a nude area called ..............species . In a primary succession on rocks , the group that invade first are ...........

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about species that invade a nude area and the specific group that invades first during primary succession on rocks.

2. **Identifying the Term for Invading Species**: The species that invade a nude area, which is a new or barren area, are referred to as **pioneer species**. These species are the first to colonize previously uninhabited or disturbed environments.

3. **Identifying the First Invaders in Primary Succession on Rocks**: In the context of primary succession, particularly on rocks, the first organisms to invade are **lichens**. Lichens are a symbiotic association between fungi and algae or cyanobacteria, and they are capable of growing on bare rock, contributing to soil formation.

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