A Review of Biogeography and Biodiversity of Western Atlantic Mollusks by Edward J

ISSN 2325-1808 (PRINT) 2325-1840 (ONLINE) http://conchologia.com NumbER Thirteen 4 june 2013 A review of Biogeography and biodiversity of western Atlantic mollusks by Edward J. Petuch. Richard E. Petit 806 Saint Charles Road North Myrtle Beach, SC 29582 [email protected] Biogeography and biodiversity of western Atlan- methodologies” must refer to the “algorithms” tic mollusks by Edward J. Petuch used to determine the percentage of endemism in 2013. CRC Press/Taylor & Francis Group the groups selected. This will be discussed later in Boca Raton, Florida. xvii + 234 pp. $159.95 this review. Introduction One chapter is devoted to each of fifteen subprovinces, some of them newly named or re- This work introduces a new biogeographic sys- fined. There are two appendices. Appendix 1 lists tem for western Atlantic mollusks based on quan- the taxa used in the provincial and subprovincial titative analysis of endemism in selected families analyses and Appendix 2 contains descriptions of of gastropods. The blurb on the back cover states: eleven new genera and subgenera and thirty-one “[This is] the first book to use quantitative meth- new species and subspecies. odologies to define marine molluscan biogeographical patterns” and “the author’s algo- As this review will show, although some intri- rithms demonstrate that the bulk of molluscan guing ideas are presented in this work it is rid- biodiversity is concentrated in forty separate cen- dled with errors that cast doubt on its reliability ters of speciation, ranging from Cape Hatteras, as does the fact that it is based entirely on large North Carolina, south to Argentina.” The author gastropods, which constitute only a small per- reviews prior biogeographic treatments and di- centage of the total western Atlantic molluscan vides the tropical western Atlantic fauna into fauna. three provinces, Carolinian, Caribbean and Brazil- The numerous illustrations, all labeled as Fig- ian. ures, include maps, scenic views, and mollusks. In his Introduction the author expresses his Of 435 nominal species of mollusks illustrated, great enthusiasm for biogeography as it is “one of 213 of them were named by Petuch. The figures the most intellectually satisfying branches of ma- are unfortunately not of high quality, with most rine biology.” In the book, biogeography, as in- being half-page or less in size. A ventral view of clusive of all the disciplines listed for it on page the newly described Cinctura in Figure 3.6 would xvi, is treated briefly in the introduction to each have been more beneficial for users than having province. Biodiversity is determined by the aver- both dorsal and ventral views of a previously age endemism in only ten families and subfami- named Aurinia in Figure 5.1, a species that does lies of marine mollusks. Despite statements to the not even enter into the biodiversity equations. contrary, some of these supraspecific groups are Some figures will be familiar to those who notoriously over-named and in a state of taxo- have read other Petuch works. However, alt- nomic flux. hough smaller, the color images of Figures 8.2 and The percentage of endemism has long been a 10.11 are much better than the full page images method of determining the limits of published in 1988. Outline maps are provided for biogeographical provinces and subprovinces. each province showing the limits of the provinces Here the author has set his own percentages, as and subprovinces. In the map of the Caribbean do many biogeography authors. The “quantitative Molluscan Province (Figure 2.4) there is an un- conchologIa ingRaTa no. 13 numbered and unlabeled large void between is in fact theoretically possible that a province northern South America and Hispaniola. The sev- could possess no endemic species at all and yet en subprovinces are numbered on the map, but have distinctive communities.” unfortunately the numbers for subprovinces 1, 2 The point here is that the definition of a prov- and 3 do not match the code numbers assigned to ince depends upon the person making the divi- them (page 177). On the other province maps sions and this misquote is not necessary to further (Figures 2.1, 10.1) the map numbers match the the provincial scheme presented. It is noted that code numbers. All the maps would be more use- Valentine referenced “the species living within ful with at least some of the countries outlined, the province”, not simply representatives of se- even if only on the coastline, especially Figure 2.6 lected family groups. of South America. There is a discussion on page 3 of The book is difficult to use as there is no index “biogeographical classifications that have been for the included taxa. The only index is to the proposed over the past 150 years.” In listing the pages prior to the two appendices, and even this three provinces recognized in this book, the final does not include taxon names in the discussions one is “the Brazilian Province that I proposed in or the figure captions. In the text prior to the ap- 1988.” What Petuch meant by that statement is pendices, numerous species are listed as endemic not known, as in 1988 there was no indication it species in families not included in Appendix 1. was novel. Perhaps he meant “a mollusk-based These are presented without author or date and Brazilian Province” as the term Brazilian Province are not in the index. As an example of the prob- has been around for many years (e.g., Ives 1891, lems encountered without an index, in the caption emending earlier usage). to Figure 3.6 “Stramonita bucheki Petuch, new species” and “Mercenaria hartae Petuch, new species” Petuch has a section on “Western Atlantic appear with no other information. In the caption paleoprovinces and paraprovincialism” beginning to Figure 5.6 slightly more information is given on page 10. No comments are here made about for “Engina dicksoni Petuch, new species … (see this section, but those interested should read Appendix 2).” One can then go to Appendix 2 and comments on Petuch’s treatment of start looking for it page-by-page. paleoprovinces by Landau, Vermeij, & da Silva (2007: 445–450) and on paraprovincialism by Ly- Provinces and Subprovinces ons (1991: 200–201). In a lengthy and interesting “history of Provinces are a useful tool in biodiversity stud- molluscan biogeographic research in the western ies. It is also instructive if they may then be sub- Atlantic” appears a statement that is part of the divided into subprovinces. To arrive at what is basis for the provincial concept presented on the presented as a precise method of division, Petuch following pages. It is stated on page 2 that “Valen- has selected ten families and subfamilies of gas- tine (1973: 337) was the first to offer a quantitative tropods for his analyses. His basis for the choice definition of a faunal province. His scheme in- of families/subfamiles is stated to be: “… because volved the use of a 50% Rule [emphasis as pub- of their relatively well-established and stable sys- lished], where at least one-half of the species liv- tematics.” This statement is difficult to accept ing within the province must be endemic.” Petuch considering that Olivinae, Conidae and the rather has cited Valentine for this “rule” before (Petuch new family Conilithidae are notoriously over- & Drolshagen 2010: 16) and it was noted to be in- named. If Conidae is well established, why are correct by Allmon (2011: 3). What Valentine wrote, eight new Conidae genera, four new Conidae spe- on the page cited by Petuch, was: “A much quot- cies, as well as one new Conilithidae genus and ed “rule” that has been used to identify provincial six new Conilithidae species, necessary in this regions is that at least one-half of the species liv- book? Additionally, ten undescribed species in ing therein must be endemic (that is, native). these two families, mostly endemic to a However, there is no special reason to employ subprovince, are listed and coded. any particular arbitrary level of endemism, and it 2 conchologIa ingRaTa no. 13 In the Olividae, only Olivinae is treated, with some of them are considered to be over-named. 35 named and two unnamed species and subspe- However, taxonomic concerns will not directly cies listed, of which Petuch is author or senior co- enter into this discussion. author of 15. Tursch & Greifeneder (2001) synon- Petuch’s method of determining endemism for ymized all of Petuch’s western Atlantic species, each provincial area is detailed on page 6, where but they recognized only three western Atlantic he mentions that he has introduced a new “25% species. Two subsequent works have reviewed Rule” [emphasis as published] for subprovinces. Oliva and recognized more western Atlantic spe- This percentage is the “subprovincial combined in- cies: Sterba (2004) and Hunon, Hoarau & Robin dex” [emphasis as published]. (2009). Summarizing across Sterba and Hunon et al., Malacolog (Rosenberg 2009) shows sixteen Appendix 1 of the book is a list of ten families western Atlantic Oliva as valid, including four or subfamilies, referred to by Petuch as “provin- Petuch species recognized by Hunon et al.: Oliva cial index taxa,” with a list of the species in each barbadensis Petuch & Sargent, 1986; Oliva sargenti that occur in the western Atlantic. The species are Petuch, 1987; Oliva goajira Petuch & Sargent, 1986; coded for the various subprovinces in which they and Oliva bayeri Petuch, 2001. The latter species is are found. These “code numbers” do not appear not even on the list of index taxa on page 188 but anywhere in the text and are identified only on is listed on page 209 from Columbia [sic; = Co- page 177.

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