ic ▁group ▁called ▁the ▁Princi p ial a ▁group . ▁This ▁group ▁is ▁one ▁of ▁three ▁possibly ▁mon oph y let ic ▁groups ▁in ▁I th on idae , ▁the ▁others ▁two ▁being ▁the ▁I th one ▁group ▁and ▁the ▁R apis ma ▁group . ▁ ▁Description ▁ ▁The ▁genus ▁is ▁identified ▁by ▁the ▁short ▁length ▁of ▁the ▁anten na e . ▁ ▁Being ▁approximately ▁ ▁long , ▁they ▁are ▁the ▁short est ▁of ▁the ▁described ▁ne urop ter ans , ▁with ▁R apis ma ▁having ▁the ▁short est ▁of ▁the ▁ext ant ▁gener a . ▁ ▁The ▁cost al ▁region ▁of ▁the ▁fore - wing ▁shows ▁a ▁regular ▁series ▁of ▁cross - ve ins ▁which ▁gives ▁the ▁appearance ▁of ▁a ▁longitud inal ▁ve in ▁in ▁the ▁base ▁area ▁of ▁the ▁region . ▁ ▁In ▁contrast ▁to ▁the ▁cross - ve ins ▁of ▁the ▁cost al ▁area , ▁the ▁cross - ve ins ▁in ▁the ▁sub cost al ▁area ▁of ▁the ▁fore - wing ▁are ▁there ▁are ▁irregular ly ▁spac ed ▁and ▁une ven . ▁ ▁The ▁area ▁between ▁the ▁radius ▁and ▁median ▁ve ins ▁is ▁not ably ▁narrow ▁near ▁the ▁fore - wing ▁base , ▁and ▁narrow s ▁towards ▁the ▁wing ▁tip ▁until ▁the ▁two ▁ve ins ▁merge . ▁As ▁with ▁many ▁I th on idea ▁gener a , ▁the ▁head ▁is ▁pulled ▁most ▁of ▁the ▁way ▁under ▁the ▁pron otal ▁shield . ▁ ▁P . ▁inc erta ▁and ▁P . ▁rud g wick ensis ▁are ▁distinguished ▁by ▁the ▁characters ▁of ▁the