oma ▁shows ▁at ▁least ▁seven ▁sections ▁on ▁the ▁upper ▁surface ▁( ter g ites ), ▁each ▁with ▁a ▁fl atten ed ▁W - sh aped ▁profile ▁composed ▁of ▁a ▁wider ▁up ward ly ▁cur ved ▁central ▁plate ▁ ▁and ▁two ▁side ▁pl ates . ▁The ▁lower ▁surface ▁of ▁the ▁op is th os oma ▁be ars ▁eight ▁visible ▁pl ates . ▁No ▁sp inner ets , ▁tel son ▁or ▁terminal ▁sp ike ▁( flag ell um ) ▁are ▁present . ▁ ▁Tax onomy ▁The ▁foss il ▁was ▁placed ▁in ▁a ▁new ▁genus , ▁Id mon ar ach ne , ▁as ▁the ▁species ▁I .   bras ieri . ▁The ▁genus ▁name ▁is ▁based ▁on ▁the ▁A rach ne ▁myth ▁in ▁which ▁Id mon ▁is ▁her ▁father , ▁and ▁is ▁intended ▁to ▁show ▁the ▁position ▁of ▁the ▁genus ▁as ▁a ▁close ▁relative ▁of ▁sp iders . ▁The ▁species ▁name ▁hon ours ▁Martin ▁David ▁Bras ier ▁for ▁his ▁contributions ▁to ▁the ▁study ▁of ▁ancient ▁life . ▁The ▁authors ▁did ▁not ▁place ▁the ▁genus ▁in ▁a ▁family ▁or ▁order . ▁ ▁Ph y log eny ▁Based ▁on ▁its ▁overall ▁morph ology , ▁Id mon ar ach ne ▁was ▁considered ▁to ▁belong ▁to ▁the ▁Ser ik odi ast ida , ▁a ▁cla de ▁of ▁t et rap ul mon ate ▁ara chn ids ▁capable ▁of ▁making ▁and ▁using ▁sil k , ▁although ▁the ▁presence ▁of ▁sil k - produ cing ▁sp ig ots ▁was ▁not ▁demonstrated . ▁Like ▁ur ar ane ids , ▁it ▁lack ed ▁sp