Reappraisal of the Middle Ordovician Trilobites from the Jigunsan Formation, Korea

Middle Ordovician trilobites of the Jigunsan Formation are reevaluated and redescribed based on the detailed analysis of cephalic structures of numerous specimens collected from an exposure in Napalgogae, Dongjeom area. Of 22 asaphid trilobite taxa known hitherto from the Jigunsan Formation. eighteen are found to be referrable to one of the following species; i.e., Dolerobasilicus yokusensis (Kobayashi, 1934), Basiliella kawasakii Kobayashi, 1934, Bastliella typicalis (Kobayashi, 1934), and Ptychopyge dongjeomensis Lee and Cheong, 1 d80. The name Ogygito1des raymondi Kobayashi. 1934 is recommended to be applied to the holotype only, while its suppposedly accompanying cranidia are transferred to Dolerobasilicus yokusensis. The remaining three species. namely, Bastlicus (?) endoi Kobayashi. 1934, Onchometopus (?) makko/ensis Kobayashi. 1934, and Asaphus (?) aff. minor (Weller. 1913), were unable to be evaluated due to poor preservation and inadequate descriptions. The generic concept of Dolerobastlicus Harrington and Leanza, 1942 is refined. Parabastlicus Kobayashi, 1934 is treated as a junior synonym of Bastliella Kobayashi, 1934. 7J-~s=_ "Ell"-lJ,..l %"J:Al"?'l91 i.+~21~oJl *2Eß"J-;=~-&--tl%-~5!.. -'f-i::~ 7.~aj~ "-J"l:l*%91 ojcFi'-3:. (cephalic structures)oJ] i::Jl~ :A)-"1]~ *~% ii}EJ-~_ii!_ 31-8:-~%-91 "-J"l:l*oJl i::Jl~ **~~ -'~:"iJ7}% ,i.js=_ß"}'iltj. :A]~77}:A] ~-&--tl%-~5!.. -'j!-i::~ ~Pj;o:J 22~91 asaphid"-J"l:l* % 18~.gi::.J-%34 7J-o] 34f 4~~5!.. -'~%"a~9Jtj; Dolerobasilicus yokusensis(Kobayashi, 1934), Basiliella kawasakii Kobayashi, 1934, Basiliella typicalis(Kobayashi, 1934), .::Lei J1.. Ptychopyge dongjeomensis Lee and Cheong, 1980. 1934\1 Kobayashi7} ~l 0J~-cj ~4f Ogygitoides91 1N.g~-5:.<>1(holotype)oJ1°J -;;-~,i.]7]uj Ogygitoides raymondi.5!.. %"a~9J-cj 1Ei'!:-% 0J-'f-~ Dolerobasilicus yokusensisoJl ~4f,..]~tj. '-foj:A] 3~. ~ Basilicus (?) endoi Kobayashi, 1934, Onchometopus (?) makkolensis Kobayashi, 1934, .::LciJ'.. Asaphus (?) aff. minor(Weller, 1913).g_5l_~o] *lß7} i::ll"-J-oJ];_~ -'1]~ß"}'iltj. 1942\1 Harrington3l} Leanza7} ~l'tl~-cj Dolerobasilicus4f91 1~\J% "~"a'\:Jß"}'ilJ'.., !E.~ 1934\1 Kobayashi7} ~l'tl~-cj Parabasiticus:!c: Basilietta91 %4f01~~ "Ö"~ ~ ß"}'il tj.