The type 'myclass' does not have a visible constructor that matches the argument list

Your problem is that you have a subclass that has a constructor that does not directly reference a parent constructor.

Thus the parent class is being implicitly constructed using the default constructor which is MapBase()

BUT MapBase does'nt have a default constructor because you declared an explicit constructor.

What you need to do is call the parent classes defined constructor from the child classes constructor like this....`

     #pragma strict
      
      public class MapBase
      {
          public var latitude : float;
          public var longitude : float;
      
          public function MapBase(latitude:float,longitude:float)
          {
              Debug.Log("MapBase invoked");
              this.latitude = latitude;
              this.longitude = longitude;
          }
      
          public function getLatitude()
          {
              return latitude;
          }
      
          public function getLongitude()
          {
              return longitude;
          }
      }
      
      public class AutoGPS extends MapBase
      {
          public function AutoGPS(latitude : float, longitude : float) 
 `                 : base(latitude,longitude)
          {
              Debug.Log(this.getLatitude());
          }
      }