AN EVALUATION OF THE TAXA MURICOPSIS AND RISOMUREX (GASTROPODA: MURICIDAE) , WITH ONE NEW SPECIES OF RISOMUREX EMILYH. VOKES DEPT. OF GEOLOGY , TULANE UNIVERSITY NEW ORLEANS, LOUISIANA a nd ROLAND HOU ART (LANDEN , BELGIUM ) SCIENTIFIC COLLABORATOR, INST/TUT ROY AL DES SCIENCES NATURELLES, BRUSSELS CONTENTS I. ABSTRACT . .. .. ..... ... ........ .. .. 63 II. INTRODUCTION . ........ 63 III. ACKNOWLEDGMENTS ..... ... ...... .. ... .. ...... ......... 65 IV. SYSTEMATIC DESCRIPTIONS . .... ........................... .. 66 V. SUPPLEMENTARY LOCALITY DATA ...... ... ...... ... ... ..... ... 85 VI. APPENDIX-COMMENTS ON THE GENUS MURICOPSIS s.s. ..... ..... 85 VII. LITERATURE CITED . ........... ....... .... .. ...... .. ... 87 ILLUSTRATIONS PLATE 1 .. .. ... 69 PLATE 2 ........ 71 PLATE 3 . ....... 73 PLATE 4 .... ...... .. ........ 75 I. ABSTRACT new species, M. (R.) withrowi , described from northern South America. Risomurex is considered to be a sub­ genus of Muricopsis, being distinguished II. INTRODUCTION from the latter by lacking true varices, Olsson and McGinty (1958, p . 40) origi­ having instead only rounded axial ridges. nally described the muricid genus Riso­ All species a·re in the Atlantic Ocean with murex without any comparison to the simi­ the majority found in the tropical western lar Muricopsis Bucquoy and Dautzenber g. Atlantic; three are from West Africa; one is 1882. As the authors noted, "Caribbean from temperate South America . One fossil species of this group have been referred to species, presumed to be the ancestral Ocenebra, Engina , Ricinula , and most re­ form, occurs in the Burdigalian of Franc e cently to Ocinebrina." They included in and Florida. The habitat of all is extremelv their new taxon four species: "Engina ., shallow water, under rocks or coral boui­ schrarn,mi Crosse, 1863 (the type ); "Fusus ·· ders, the deepest known occurrence is no muricoides C. B. Adams , 1845; "Ricinula ., more than 30 m (for roseus) but most are in­ rosea Reeve , 1846; and "Murex " alveatus tertidal. All are small; the largest (neco­ Kiener, 1842. They added that the radula cheanus and gilbertharrisi) are under 25 of R. schrammi is very close to that of "M .., mm in height and most are about 15 mm. In alveatus , which is true , as both Risomu rex all, there are 11 species recognized : two and Favartia, to which alveatus is more fossilforms; one Pliocene-Recent form; the correctly assigned (as subgenus Caribiella), remaining all Recent, of which one is a are now placed in the subfamily Muricop- EDITORIAL COMMITTEE FOR THIS PAPER ANTHONY D'ATTILIO, Natural History Museum, San Diego , California A. MYRA KEEN , Department of Geology, Stanford University (Emeritu s), Stanford , California J. GIBSON-SMITH, Escuela de Geologia , Minas y Geofisica, Univ ersidad Central de Venezuela, Caracas, Venezuela 63 64 Tulane Studies in Geology and Paleontology Vol.rn sinae, characterized by having a three-di­ conspicuous purple aperture, the radulaof mensional rachidian tooth . the group is muricine, as is the operculum, The only taxon with which Olsson and Morula differs from Risomurex in the na­ McGinty compared Risomurex was the ture of the radula (muricine not murico~ Mediterranean Ocinebrina, no doubt du e sine), in the arrangement of the labrald e­ to Bartsch and Rehder's placement of their nticles, and in having a strong plai t in the "Tritonalia " caribbaea in the subgenu s center of the columellar wall, just opposite Ocinebrina, and Abbott's (1954, p. 44) sub­ the largest of the labral denticl es, greatly sequent transfer of that species to constricting the apertural opening. synonymy with what he then termed In 1971 Vokes considered the genus "Ocenebra (Ocinebrina) muricoides (Ad­ Risomurex as being in the thaid family, ams)." somewhere near Drupa , and did not in­ There is a superficial resemblance be­ clude the species in her "Catalogue of het tween Ocinebrina Jousseaume and genus Mur ex." But , in 1976, Radwin and Risomurex, in that both have non-varicat e D'Attilio observed that the radula, shell, shells, with heavily denticulated aper­ and protoconch of the three species of tures. However, this is due to convergenc e Risomurex are muricid, nearly identicalto and Ocinebrina, as Abbott indicated, is a the genus Muricopsis, and they synon­ subgenus of Ocenebra, placed in the sub­ ymized the two taxa. Their illu strationof family Ocenebrinae. The latter is distin­ the radula of "M. sch rammi " (= M. defor­ guished by having calcitic (not aragonitic) mis) (1976, fig. 112) shows the characteris­ shells, purpuroid opercula, thaid radulae, tic three-dim ens ional rachidian toothof the an d (usually) a sealed siphonal canal. subfamily. For the radula of "Riso­ In addition to Ocinebrina, the member s murex roseus ," unfortunately they illus­ of this group have been placed in a variety trated some ocenebrine species, per haps of muricid, thaid, and even buccinid gen­ Trachypollia nodulosa (Adams, 1845) (com· era. The latter usually has been Engina pare Rad win and D' Attilio , 1976, fig, 110, Gray, 1847 (type species: E. zonata Gray ), with the same authors, 1972, fig. 11). superficially similar with its biconic, non­ Although we are in complete agree me varicate shell and denticulated aperture. nt that Risom urex is closely allied with But , in addition to th e buccinid radula, th e Muricopsis, the non-varicate shell of two shell forms may be distinguished by Risomurex, in contrast to the varicate shell the series of small denticles · extendin g of Muricopsis, seems sufficient justific along the entire length ation of the columellar lip for separating the two* at inEngina. the subgeneric level (compare pl. 2, fig. 11 with others!. Initially most species were described as Thi s deci sion i s further strengthened by "Ricinula" or "Sistrum ," both of which are the discovery of two additional Risomure.r synonyms of Drupa Roding, 1798 (type species, one of which is describ ed below, species : D. morum Roding), a th a id genus that are in turn closely related to a fossil with numerous accessory denticles on th e form described from the Mioc ene of rachidian tooth and a purpuroid oper­ France as "Jania " crassicosta Benoist. culum. However, at the time of this usage , spec ies now referred to Morula Schu­ * macher, 1817 (type species: Morula papil­ This same conclusion was reach ed i ndepen­ dently by Kemperman and Coomans (19 losa Schumacher, 1817, Drupa 84),in = uva Rod­ a paper th at appeared as ours wa s nearing ing, 1798) were also included in Drupa s.l., completion. Their concl usion s are essentially in and there is a stro n ge r res emb lance be­ agreement with ours (considerabl y blunting tween these forms and those here placed the impact of our paper), their most important in Riso murex . contribution being the observation that the The gen us Morula , which is Indo-Pacific shell usually considered to be M. (R.) schramm1 in distribution, includes a group of species by a ll authors since O lsso n a nd McGinty isno! that have heavily denticulated apertures that form but another , which they named asa new species. In our op inion, the species and non -varicate s hell s with nodulose ax ial in que stion is M. (R .) deformis (Reeve), which sculpture . Although resembling members they state is s imil ar to their new species butnot of Drupa in she ll from, especia lly in the the same. No. 2 Muricopsis and Risomurex 65 1873, but which also occurs in the Earlv 5. withrowi Vokes and Houart, n. sp. Miocene Chipola Formation of northwest­ From northern coast of South Americ a ern Florida (see pl. 3, figs. 6, 7). Although (Colombia and Venezuela ), Trinidad , described in the buccinid genus Jania, the Tobago, and Netherlands An tilles. French species is unquestionably a Riso­ 6. rutilus (Reeve ). Ghana , West Africa. murex, the earliest member of the line yet 7. fusiformis (Gmelin ). Senegal, West Af­ discovered. Thus, the group has had a long rica . geologic history of being distinct from 8. suga (Fischer-Piette). Senegal, We st Muricopsis, which first appears in the Mid­ Africa. dle Eocene of California (Muricopsis vis­ 9. galbensis (Jung). Early Pliocene of taensis Givens and Kennedy , 1976). Trinidad. We agree with Olsson and McGinty 10. necocheanus (Pilsbry ). The only temp­ (1958) and Kemperman and Coomans e.rate species, found from centr al (1984)as to the species included in this sub­ Brazil to northern Argentina. genus [excluding "M ." alveatus, which as 11. crassicosta (Benoist ). Early Miocen e noted above is better referred to Favartia (Burdigalian) of France and Florida. (Caribiella) and is perhaps better known to readers as Murex intermedius C. B. III. ACKNOWLEDGMENTS Adams, 1850, non M . intermedius Brocchi, The main framework of this paper is 1814.]What there is not agreement on is based upon work done at the British the name by which these species are to be Museum (Natural History ) and the called. The nomenclature of the entire Museum National d'Histoire Naturelle , group is unusually complicated not only at Paris, and to the members of the mollu s­ the generic level but also at the species can sections of these two institutions: John level. D. Taylor and Kathie Way, of the first; and Our studies show there are eleven Philippe Bouchet and J . E. Pointier, of the species that may be assigned to the sub­ second, we extend our deepest gratitude genus Risomurex. These are : for the multitude of favors rendered. In ad­ 1. deformis (Reeve) ( = schrammi of au­ dition, this paper has required more than thors; =mosquitensis Kemperman and the usual amount of borrowing of speci­ Coomans, 1984). Occurring only along mens and seeking of information. For all of the coast of Caribbean Central Ameri­ this help we wish to acknowledge our in­ ca, from the Chinchorro Banks, debtedness to the following persons: the Mexico, to Panama; a single dead late Joseph Rosewater and Thomas R. specimen reported from the north Waller, U.