鶏口拳
Keikō ken
One knuckle fist

Also known as ippon ken 一本拳, oniken 鬼拳 (extended knuckle fist), shoken 初拳 (first [knuckle] fist), hitosashi ippon ken 人差し一本拳 (forefinger one knuckle fist), hitosashi yubi ippon ken 人差し指一本拳 (forefinger one knuckle fist), fèng yǎn quán 鳳眼拳 (phoenix eye fist, Mandarin).

Keikō ken can also refer to a “chicken beak” fist.

 

          

Nakayama’s hitosashi ippon ken is formed with the thumb alongside the index finger

Shōtōkan

Nakayama Masatoshi, Best Karate 1: Comprehensive

 

 

Migi shoken zuki
Shoken is a characteristic fist in Uechi ryū

Karate Klub Kranj

 

Uechi ryū forms its shoken is with the thumb under the forefinger. Shintani Wadōkai does the same for ippon ken.

Ihor Rymaruk

Karate: A Master's Secrets of Uechi-Ryu

 

Phoenix Eye Fist 鳳眼拳
Cheong Cheng Leong
Phoenix Eye Fist Kung Fu (Chukka Shaolin)

The Stealing Hands of Phoenix Eye Fist

 

The Phoenix Eye fist has the thumb under the index finger as well

Cheon Cheng Leong and Donn F. Draeger, Phoenix-Eye Fist: A Shaolin Fighting Art of South China