CENOZOIC MURI lDAE OF THE \XIE TERN ATLANTIC REGION Parr 111 -CI IZ COR.F.US I PH Y LLONOTl'S1 ! ~M IL y IL YOTrns 'II !AXE I :11nrnsl]'J CONTENTS Page I. ABSTRA CT 133 J L INTRODUCTION 133 !IL ACK OWLEDG1'1ENTS 136 IV. SYSTE1\IATIC: DESC IU PTIO NS 136 V. NOTES ON Tl IE WEST COAST PECl.ES OF Pl-JYLLONOTUS 160 VL LOCALJTY DATA 162 VJ!. L!TEHAT LIRE CITED l6L1 ILLUSTRATIONS TABLE l 134 PL11TE I 151 PLATE 2 153 PLATE 3 155 Pl.ATE 4 157 PLATE 5 159 PLATE 6 l6l J. ABST!{ACI genus is and has alw ays been confined ro ThC::re arc: 18 species of the muricine sub­ rhe Ne"' \\;torld. gc: nu s Phillrmot11J recognized in rhe Ceno­ All 18 western Arl ami c Cenozoic species zoic of the western Arlanric region; three <Ir<: treared sysrcmarica ll y, including one new of these species are exra nr. The earl iest species Chicore11s I Phyl!o110111s) leo11e11sis known spec ies here referred to Phr/101101111 E. H. Vokes, from rhe Chocrnwharchee For­ is from rhc lower Oligocene Red Bi uff Clay m:H ion of nonhtrn Fl or id a. of Miss issippi. The group is bdic:ved w have been derived from a 1-/exaplc.\ ancesror 11. lNTHODllCT IO because of simil arities of prornconch t)'pe in The generic name Ph;l/0110/m was pro­ rhe earlier foss il species and of coloration in pos<:d in 18:)'.\ by Swa in so n (exp!. to plate the Recent species. Phyllo11011n is thought 100) in a rnb le wirh no species being to have given ri st ro rhe subgenc:ra Chicore- n:imed, bur was described as "Canal moder­ 11.1 s.s. and Sirn111s. ate . Varices foli ated, mosrlr three." ln An endtmic we.;rern Arlanric fo rm, Phil­ rhe same \\'Ork, on pl art I 09, he rhen figured lo110111s migrated th rough rhe Isthmian pass­ and described rhe firsr species ro be referred age:, probably in !:tre Miocene timt, and ro this new genus: ilfm·ex !Phyllo110111s) im­ evolved into rhc: fou r species presently peri,di.1 var. a. This variety was Stated ro known from rhc: casrc: rn Pac ifi c. The sub- differ from the rypical imperialis in having ED ITOR IAL CO~l~ ll'I TEE FOR Tl/I S PAP ER: A. MYRA KEEN. Deparrm<:nr of Gc:o J,igy, rnnford University, Stanford, California NOR1'1AN E. \XIEJ SJJORD, Florida Scare University, Tallahassee, Fl orida D 1rn1D \Xl 1LSON, United rares Geological Su rvey, \Xfas hingron, D . C. C. ervthrostomus (2) C. rcgius (2) C. margaritensis cmconEus s.s. (:!) I I C. 1>0mum (2) c _ erylhrostomus (:?) C. rip:i.rius (.I) '"\ /"""-" ClllCOnEUS (SillATUS) (4) C . infruqucns t4} f....: cf. tritonopsis (2) c. fol id0<lcs ( 2) ~~I(:.!) C. trophoniformis C. davisi C. trltonopsis (2) C. Stctopus (5) - ~~C. mississippiensis (5) - C. ciormuni (5) Table r P hylogen~ of CHI COR EUS (P llY LLO ~ OTUS) and related forms. (Number of nuclear whorls in p:i..rcnthcses wher e known.) No. 3 Cenozoic i\lmicida11- lll 135 a rose colored aperture rather than an oranoe Miocene rime from rhe ancestral Phyl/011ot11r one. lt is nor felt roday that this diffcren~e rype for rhe lower Miocene species of Si­ is worthy of a separate name and the type rctlm all have the four whorl nucleus but of Ph ,yl/01101111 is J\l11rex i111perir1lis var. a rhe species living roday l1ave rhe t\\'O whorl Swainson=M. im perialis Swainson ( =1\lll­ type. Table I depicts these relationships as rex mr1rgari1e11sis Abbott, new name for J\!. envisioned by the writer. imperie1/is Swainson, 183 l, 11011 /\!. i111pe1i ­ The Chicore11S s.s. line probably comes cdis Fischer, 1807.) off this same early Phyllo110111s stock. The The characters w hi ch serve ro unite tht first species considered by the writer ro be species o f Phyl/0110111s are the irregular referable ro Chicore!IS s.s. are the !are lower placement of the varices with respect to Miocene C. lepidod11.r and C. d11jr1rdi11oides. each other; the appearance of an irregular The division at this point is somewhat ar­ nurnbtr of varices per whorl; and the varical bitrary for rhc:se early species could easily ornamentation being li mited ro no Illorc have remained with rhe ancestral group, but than short open spines, or often completely it is in these rwo species that the foliaceous lacking. In contrast the members of Chi­ varices and rhe pronOLrnced anal notch firsr core11s s.s. usually, although not always, have appear. These two characrerisrics are the three rather foliaceus, regularly aligned distinguishing Illarks of the Chicore/IJ s.s. varices and a marked anal notch. The type group. C. fo/idodes was also originally in­ species of the rwo groups are quire distinc­ cluded in rhis Chicore11s s.s. group in rbc tive but many species are intermediate in previous monograph (Vokes, l 965) but character and difficult to assign ro one or later work on the phylogeny has indicated rhe other. The early species here referred that this species should be placed in PhJ'l­ ro PhJ·llo110111s are in rhis ambiguous posi­ /0110111.1. The flaring parietal sh ield, such an tion as befits an emerging subgeneric dif­ obvious characrerisric in the Recent PhJ'l­ ferentiation and they are placed here be­ /rmolm. does not appear until the late Mio­ cause of the phylogenetic developlllenr of cene: with C. globns11s. Except for the lack the line rather than because of a strong re­ of this parietal lip rhe early species more semblance ro the type species of Phyl/011nt11.1. nearly resemble the Phyl/0110111s rype than The Ph yl/011ot11.r Jine evidently diverged they do the Chicorem s.s. type and so the from a Hexaplex ancesror in the Jarc Eo­ species which are ancestral to both Jines are cene. These two groups still share certain placed with PhJlln110/11S rather than with marked rrai rs such as a tendency ro have Chicnre11s s.s. Ir is an unforrunare rule of brown and white spiral color bands and nomenclarnre that the generic name of a pink apertures. Both also have a pernliar group is determined by priority rather than rype of proroconch in the early Terriary phylogeny for rhe more logical sequence species. In the subfalllily Muricinae there would be ro have the groups named Phyl­ are rwo d istinct rypes of nuclear whorls. /0110/11.r s.s. and Phyllonot11s (Chicore11s). One of these is found in the P1ery110/111 This would be a better expression of the g roup and has o nl y two so!llewhat bulbous true affiliation of the Jines. whorls. The other rype appears in the In rhe previous Chicorem monograph /-Jexr1plex group and in the early Phyl/0110/m (Vokes, 1965, p. 182) it was suggested that and consists of four or five smooth, conical rhe Chicore11s line originated from a Ptery- whorls. 110111s ancesror. Additional work on Phyl­ These rwo types of embryonic shells recur !n110111s indicates that Ph,,llonotm and Chi­ throughout rhe Muricinae. Ir would appear <'ore11s are closely related. to each other bur rhar the four or five whorl rype is more more distantly related to P1ery110111s. The primitive as it is seen primarily in :Eocene nature of the development of rhe early ro Miocene species, bur there are Recent whorls is completely di fferenr. In the Ptery- species which also show this rype of nucleus 110!11s group rhe first post-nuclear whorl has so that rhe true significance of rhe differ­ six small distinct varices which, on th e sec­ ence in embryonic shell is nor clear. The ond whorl, become three varices and three trend roward a decrease in the number of i nrervaricaJ nodes. In Chicore!IS and in whorls from four ro rwo occurs i ndepen­ Phy/!0110111s the first post-nuclear whorl has den rly in several Jines. Jr is assumed thar about a dozen equal axial nodes. In Chi­ the Chicorem (Sirc1111s) line diverged in early core11s on rhe second or third whorl certain Vol. 5 136 T11/,111e Sl!lrlie.r i11 Geology of chese are srrengrhened ro form rh rec (or IV. SYST Hl1\TI C DESCL\IPTIONS four ) var ices and rhe remainder become Phylum J\ fou.L;scA ill(ervarica l nodes. ln rhe Pbyl!o1101m group Class G,1STHO PODA rhe early posr-nuclear whorls arc identical Subclass PtWSO HRA NCH 11\ ro rhose of Cbicore/IS and nor ull(il rhe rhird Order N EOGASTROPOD1\ or fourrh post-nuclear whorl are cerrain of Suborder STENOG l.OSSA rhe nodes srrengrhened ro form var ices. Bur rhese va rices are irrcgubrly pl:1ced wich F.1111 ily 1'f L' IU CIllA I: rderencc ro the preceding whorl and there Subfamily i\ [1 11u c 1NAI' is no column formed up the spire by rhe Cenus Ci 11COHFL 'S Moll(forr. 1810 var ices such as that presen r in Chiwre11.1. Subgenus P1-tYl.LONOTl lS Swa in so n, 18 .~ .) The members of rht Ph1//0110/111 group (HtCOHEl'.S ( PHYl.1.0NOTl lS) are subtropical shallow warer dwellers and MISSISSI l'PI ENSIS (Conrad) are acrive predarors or scavenge rs. The Pia re I. figs. 6- 7 group is confined rn rhe New W'orld where rhere are seve n Recent species, th ree in the .11 ure.·· mississi}J/>irnsi., CON RAD, 18-17 [lR-18] , Acacl.