(2788) Proposal to reject the name Radermachia rotunda (Artocarpus rotundus) (Moraceae)

Abstract

(2788) Radermachia rotunda Houtt., Nat. Hist. 2(11): 455. 3 Dec 1779 [Angiosp.: Mor.], nom. utique rej. prop. Typus: non designatus. The name Artocarpus rigidus Blume (Bijdr. Fl. Ned. Ind.: 482. 1825, ‘rigida’) (Moraceae) has long been in near-exclusive use for a well-known species of wild fruit tree common throughout much of the Malesian region. It has become clear, however, that the earlier Artocarpus rotundus (Houtt.) Panzer (in Christmann, Vollst. Pflanzensyst. 10: 380. 1783, ‘rotunda’), based on Radermachia rotunda Houtt. (Nat. Hist. 2(11): 455. 1779), likely refers to the same species. To avoid confusion and taxonomic instability, we propose that the name Radermachia rotunda be rejected. No traceable original material exists for Radermachia rotunda, despite a recent search at G, where the main part of Houttuyn's herbarium resides (Wijnands & al. in Candollea 72: 155–198. 2017). The brief protologue provided the vernacular name “Mandelique” and three diagnostic characters: (1) the leaves are the same as those of Radermachia integra Thunb. (= Artocarpus integer (Thunb.) Merr.) but without roughness; (2) the pistillate inflorescences are completely round; and (3) the rough fruit grows to the size of a child's head. Artocarpus rigidus was validly published over 40 years later with a somewhat more detailed protologue and without mention of Artocarpus rotundus. The lectotype, without information on the collector, is preserved at Leiden (Java, barcode L 0039903). Merrill (in J. Arnold Arbor. 19: 331. 1938), in a paper on Houttuyn's names, concluded, based on the protologue, that Radermachia rotunda was the same species as Artocarpus rigidus, finding further confirmation in the vernacular name “mandeliké” associated by later authors with A. rigidus (Koorders & Valeton in Bijdr. Kennis Boomsorten Java 11: 19. 1906; also Hasskarl, Aanteek. Nut Java Pl.: 27. 1845; Teijsmann & Binnendijk, Cat. Hort. Bot. Bogor: 85. 1866). Merrill (l.c.) therefore reduced Artocarpus rigidus to synonymy under Artocarpus rotundus. In her monograph of Artocarpus, Jarrett (in J. Arnold Arbor. 40: 118, 153–154. 1959) disagreed and considered Radermachia rotunda Houtt. to be a nomen dubium, noting that although Mandelique was a common name for A. rigidus, the protologue was too vague because the leaves of that species are abaxially scabrid, and the infructescence is smaller than a child's head. She, therefore, maintained Artocarpus rigidus as the accepted name for the species. A more forgiving approach might note that although the leaves of Artocarpus rigidus are scabrid abaxially, they are usually (although not always) smooth adaxially, and that larger infructescences may at least attain the size of an infant's (if not a child's) head. Moreover, among the Javan species not separately dealt with by Houttuyn, Artocarpus rigidus is really the only good candidate for Radermachia rotunda. Artocarpus rotundus was apparently overlooked by early authors, perhaps, as Merrill speculated, because neither Houttuyn nor Panzer indicated their species as new. Blume's Artocarpus rigidus, on the other hand, was widely used and has appeared in all of the major treatments of Artocarpus over the past 170 years (Trécul in Ann. Sci. Nat., Bot., sér. 3, 8: 114. 1847; Miquel in Zollinger, Syst. Verz. 2: 89, 95. 1854–1855, Fl. Ned. Ind. 1: 286. 1859, Fl. Ned. Ind., Eerste Bijv.: 418. 1861, in Ann. Mus. Bot. Lugduno-Batavi 3: 211. 1867; King in Hooker, Fl. Brit. India 5: 540. 1888, in Ann. Roy. Bot. Gard. Calcutta 2: 8, t. 3. 1889; Ridley in J. Straits Branch Roy. Asiat. Soc. 33: 147. 1900, Fl. Malay Penins. 3: 352. 1924; Koorders & Valeton, l.c.: 17; Koorders, Exkurs.-Fl. Java 2: 93. 1912; Heyne, Nutt. Pl. Ned.-Ind.: 564. 1927; Burkill, Dict. Econ. Prod. Malay Penins.: 258. 1935; Corner, Wayside Trees Malaya: 657, t. 198, 199. 1940; Browne, Forest Trees Sarawak Brunei: 353. 1955; Jarrett, l.c.: 150; Kochummen, Tree Fl. Malaya 3: 131, t. 6. 1978, Tree Fl. Sabah Sarawak 3: 208, t. 5. 2000; Berg & al., Fl. Males., Ser. 1, 17(1): 100. 2006, Fl. Thailand 10(4): 17. 2011). By contrast, no modern treatments of Artocarpus have taken up Merrill's approach, and Artocarpus rotundus remains an obscure name that likely applies to a well-known species. Failure to reject Radermachia rotunda would uphold the principle of priority but would also promote nomenclatural instability and confusion. Because opinions have differed as to the application of the name, future authors who consider the protologue sufficient to equate the name with Artocarpus rigidus may feel compelled to follow Merrill and adopt A. rotundus, even while authors who agree with Jarrett continue to use A. rigidus. Rejecting Radermachia rotunda would eliminate that possibility and promote stability in the nomenclature of this species. The authors thank John McNeill for helpful consultation in preparing this proposal and Fred Stauffer for checking specimens at G. This research was supported by the US National Science Foundation (DBI 1711391) and the National Parks Board of Singapore.