Decalvan Brothers

The Decalvan Brothers are two infamous New World pirates who allied themselves with Whitebeard.

Appearance
The Decalvan Brothers appear to be twins, and both wear overalls. Both have wide faces (though one of them is wider than the other) and flowing black hair. The one with the wider face has sharper teeth. Each brother opens one of their eyes which is large and black around the rim, and closes the other which has a scar over it; which eye they open and close are opposite to one another.

They both wear a pirate tricorn hat with polka dots bandanna underneath it. The hat bears their Jolly Roger: two skulls and a cross-bone, with a wavy design over it. They both wear long gloves with razor-sharp nails at the end on both hands.

Abilities and Power
The Decalvan Brothers have managed to make themselves an infamous reputation in the New World, and have managed to ally themselves with Whitebeard. After Squardo, they are Whitebeard's choice in leading the allies to attack the Marine warships. They wear gloves with razor-sharp nails at the end, which are most likely used in battle, similar to Sham and Buchi, the Nyaban Brothers, of the Black Cat Pirates, albeit much stronger.

Marineford arc
The Decalvan Brothers and their crew are first seen, along with a fleet of 42 other infamous pirate crews, allied with the Whitebeard Pirates, attacking Marineford to save Portgas D. Ace from his execution.

After failing to reach Squardo, Whitebeard contacted the Decalvan Brothers and gave them, along with certain other captains, the command of all the New World pirates in retaliation to Ace's early execution time.

After Whitebeard was stabbed by Squardo, they were seen commenting on how ashamed he must be feeling.

They were later seen among the group of New World captains who were backing up Luffy and Ivankov on Whitebeard's orders.

When the Blackbeard Pirates launched a barrage of bullets and blades at Whitebeard killing in the process, the Decalvan Brothers were seen crying.

Major Battles

 * Decalvan Brothers, Whitebeard Pirates and other allies vs. Marines and Shichibukai

Manga and Anime Differences
In the anime, an additional scene was shown that the Decalvan Brothers fought against Thatch and were about to beat him when Ace joined the fight. The outcome is unknown but it is very likely that the brothers were overpowered by the two commanders.