It is something between X-Wings and Swordfish.

X-Wings requires the possibilities for a number to be in 4 cells, while swordfish requires them to be in 6 to 9 cells.

The new pattern instead uses 5 cells.

The 5 cells must be at the vertices of a 5-sided polygon; it's easy to see that for this to happen, two sides must be along a row, two sides along a column, and the fifth side must have the two vertices in the same box.

The possible layouts are therefore like these:

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`. . . | . . . | . . . . . . | . . . | . . . . . . | . . . | . . .`

. . . | *---------* . . . *-------------* . . . *-------------* .

. . . | | . . | . | . . . | | . . . | . | . . . | | . . . | . | .

---------|---------|--- -----|-------------|--- -----|-------------|---

. . . | *\. . | . | . . . | | . . . | . | . . . *-----------* | .

. . . | . \ . | . | . . . | | . . . | . | . . . . | . . . | .\| .

. . . | . .\*-----* . . . | | . . . | . | . . . . | . . . | . * .

----------------------- -----|-------------|--- -----------------------

. . . | . . . | . . . *\--|-------------* . . . . | . . . | . . .

. . . | . . . | . . . . \ | | . . . | . . . . . . | . . . | . . .

. . . | . . . | . . . . .\* | . . . | . . . . . . | . . . | . . .

Due to the second layout, I've called this pattern "Turbot Fish".

We'll call a side "strong" if the two vertices it connects are the only two places where the number can be placed in the row/column/box defined by the side; "weak" if the number can be placed somewhere else.

To have a Turbot Fish, you need four or three strong sides (in any position), or two non consecutive ones.

Let's see what happens with four strong sides, for example let's say the diagonal side is the weak one (the reasoning is the same for any side).

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`. . . | . . . | . . .`

. . . | B---------C .

. . . | | . . | . | .

---------|---------|----

. . . | A . . | . | .

. . . | . . . | . | .

. . . | . . E-----D .

------------------------

. . . | . . . | . . .

. . . | . . . | . . .

. . . | . . . | . . .

If our number is in A, then it must also be in C and in E. But A and E are in the same box, so it cannot be in both of them at the same time; therefore we have a contradiction.

The number must therefore be in B and in D. So we can put it there and continue with the puzzle.

This also shows that a Turbot Fish cannot have five strong sides, because that would lead to an unavoidable contradiction.

If there are three strong sides, the two weak sides can be either consecutive, or separated by a strong side. Let's see both cases.

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`. . . | . . . | . . .`

. . . | B---------C .

. . . | . . . | . | .

-------------------|----

. . . | A\. . | . | .

. . . | . \ . | . | .

. . . | . .\E | . D .

------------------------

. . . | . . . | . . .

. . . | . . . | . . .

. . . | . . . | . . .

Here the two weak sides are separated.

We can say that our number must be either in A or in E.

If it is in A, then it's not in B, so it must be in C.

If it is in E, then it's not in D, so it must be in C.

In either case, our number is in C. So we can put it there and continue with the puzzle.

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`. . . | . . . | . . .`

. . . | B---------C .

. . . | | . . | . | .

---------|---------|----

. . . | A . . | . | .

. . . | . . . | . | .

. . . | . . E | . D .

------------------------

. . . | . . . | . . .

. . . | . . . | . . .

. . . | . . . | . . .

Here the two weak sides are consecutive.

The only thing we can say in this case is that out number is either in A and C or in B and D. In either case, it cannot be in E. Therefore we can remove the number from the possibilities for E, and continue with the puzzle.

Finally, let's see what happens with two non consecutive strong sides.

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`. . . | . . . | . . .`

. . . | B . . | . C .

. . . | | . . | . . .

---------|--------------

. . . | A . . | . . .

. . . | . . . | . . .

. . . | . . E-----D .

------------------------

. . . | . . . | . . .

. . . | . . . | . . .

. . . | . . . | . . .

Our number cannot be in both A and E at the same time. Therefore it must be in at least one of B and D. So it cannot be in C. Therefore we can remove the number from the possibilities for C, and continue with the puzzle.

Well, that's all. The description was a bit long, but I think this pattern is quite neat, and easy to understand.

Here are a few problems that can be solved using this pattern.

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`..4.9.8.6`

.316.....

2........

.....5...

..6.1.9..

...4.....

........7

.....742.

8.9.6.3..

..5.9.8.6

.316.....

2........

.....5...

..9.1.3..

...4.....

........7

.....742.

8.6.3.9..

..6.2.7.5

.396.....

8........

.....5...

..2.1.6..

...4.....

........4

.....732.

7.8.9.1..

..6.2.1.5

.396.....

7........

.....5...

..2.1.6..

...4.....

........7

.....732.

8.1.6.9..