(2949) Proposal to conserve the name Quercus pacifica Nixon & C.H. Mull. against Q. pacifica Knowlt. (Fagaceae)

Abstract

(2949) Quercus pacifica Nixon & C.H. Mull. in Novon 4: 391. 30 Nov 1994 [Angiosp.: Fag.], nom. cons. prop. Typus: U.S.A., California, Santa Barbara Co., rocky slope E. of Pelican Bay, Santa Cruz Island, alt. 100 ft., Clokey 4893 (BH-CHM). (H) Quercus pacifica Knowlt. in Rep. (Annual) U.S. Geol. Surv. 20(3): 43, t. 4, fig. 9, 10. 1900 [Foss.], nom. rej. prop. Typus: non designatus. In 1994, K.C. Nixon and C.H. Muller recognized the taxonomic distinctness of populations of shrubby oaks on three islands off the coast of southern California (Santa Cruz, Santa Catalina, and Santa Rosa Islands), and described them as a new species, Quercus pacifica Nixon & C.H. Mull. (in Novon 4: 391–392. 1994) with the holotype cited above. Subsequent genetic research has confirmed the distinctness of this taxon (Backs & Ashley in Amer. J. Bot. 103: 2115–2125. 2016). The taxon and the habitat are both endangered, so the taxon is subject to monitoring and conservation efforts across its limited range. Unfortunately, an earlier Quercus pacifica was published by F.H. Knowlton (in Rep. (Annual) U.S. Geol. Surv. 20(3): 43, t. 4, fig. 9, 10. 1900), based on Eocene fossils from Oregon, U.S.A. This was in a short paper, published as part of a geological report on a mining district in southern Oregon. Roland W. Brown (in J. Wash. Acad. Sci. 46: 104–108. 1956) subsequently excluded Q. pacifica Knowlt. from Fagaceae and made the new combination Caesalpinia pacifica (Knowlt.) R.W. Br. The placement in Fabaceae subfam. Caesalpinioideae, though not the assignment to Caesalpinia, was supported by Herendeen & Dilcher (in Amer. J. Bot. 78: 1–12. 1991). The priority of Knowlton's name over Q. pacifica Nixon & C.H. Mull. was first noted by Piers Trehane in the International Oak Society Checklist (http://www.oaknames.org/search/fullname.asp?id=506), where he said, “Nixon's name needs to be proposed for conservation”, but Trehane died before publishing a proposal. The name Quercus pacifica Nixon & C.H. Mull. has been used for this species in all recent references that deal with oaks of the region (e.g., Nixon & Muller in FNA Ed. Comm., Fl. N. Amer. N. Mex. 3: 471–506. 1997; Junak & al. in Barbour & al., Terrestr. Veg. California, ed. 3: 229–252. 2007; Tucker in Baldwin & al., Jepson Manual, ed. 2: 803–808. 2012; Jerome & al., Red List US Oaks. 2017). The species is considered endangered (Jerome & al., l.c.), so it is subject to monitoring and conservation efforts across its limited range, resulting in a plethora of studies, including studies of genetic structure and reproductive biology (Knapp in Standiforth & al., Proc. Fifth Symp. Oak Woodlands. 2002; Knapp, Oak Ecosyst. Restorat. Santa Catalina Island, California. 2011; in Monogr. W. N. Amer. Naturalist 7: 421–434. 2014; Pesendorfer & al. in Monogr. W. N. Amer. Naturalist 7: 246–259. 2014; in Curr. Zool. 63: 363–367. 2017; Backs & Ashley, l.c.) and conservation plans, all of which use the name Q. pacifica. Furthermore, the species is locally dominant in its very limited range, so its name forms part of the formal names of several communities in the widely used classification of California vegetation by Sawyer & al. (Manual California Veg., ed. 2. 2009), including the “Quercus dumosa – Quercus pacifica Alliance” and six formally named Associations. These vegetation type names are widely used in ecological and conservation studies of all groups of organisms, and all would have to be changed if the name of the co-dominant, Q. pacifica, were to change. Replacing Q. pacifica Nixon & C.H. Mull. with another name would therefore cause significant confusion among many active conservation programs as well as in the scientific literature. On the other hand, there is no reason to preserve the name Q. pacifica Knowlt., the basis of which is actually a legume. Conservation of Q. pacifica Nixon & C.H. Mull. will not affect the name Caesalpinia pacifica (Knowlt.) R.W. Br.; although Q. pacifica Knowlt. cannot be the correct name for a taxon when a later homonym has been conserved, it remains a legitimate name, and may serve as basionym for another combination (Art. 56 Note 1 of the ICN, Turland & al. in Regnum Veg. 159. 2018). ATW, https://orcid.org/0000-0002-7983-6374