Question

Which of the following is concave vein

• A. Costa
• B. Anterior media
• C. Radio-sector
• D. Anterior cubitus

Hint:

To remember the sequence of alternating wing veins starting from the leading edge: Costa (+), Subcosta (-), Radius (+), Radial Sector (-), Media [MA (+), MP (-)], Cubitus [CuA (+), CuP (-)].

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
In the Comstock-Needham system of wing venation, insect wings are not flat; they are pleated.
This pleating forms alternating ridges and valleys, termed convex (+) and concave (-) veins, which provide structural strength during flight.
Detailed Explanation:
The main longitudinal veins alternate between convex (folding upward) and concave (folding downward):
1. Costa (C): Typically runs along the anterior margin and is always a convex (+) vein.
2. Subcosta (Sc): Lies behind the Costa and is a concave (-) vein.
3. Radius (R): Runs behind the Subcosta and is a convex (+) vein.
4. Radial Sector (Rs) Radio-sector: The posterior branch of the Radius. It is a concave (-) vein.
5. Media (M): Divides into:
- Anterior Media (MA): A convex (+) vein.
- Posterior Media (MP): A concave (-) vein.
6. Cubitus (Cu): Divides into:
- Anterior Cubitus (CuA): A convex (+) vein.
- Posterior Cubitus (CuP): A concave (-) vein.
From the options, only the Radio-sector (Rs) is always a concave vein.

Step 2: Final Answer:
The concave vein among the options is the Radio-sector.