A SYNOPSIS OF THE GENUSECHINOPEPON(CUCURBITACEAE:SICYEAE), INCLUDINGTHREE NEW TAXA1Alex K. Monro2 and Peter J. Stafford2ABSTRACT Following a palynological and general morphological survey, the genus Echinopepon (Cucurbitaceae) has been dividedinto three species groups on the basis of stamen and pollen morphology. Three new species of Echinopepon are describedand illustrated: E. tultitlanapaensis A. K. Monro & Staff., E. belizensis A. K. Monro & Staff., and E. micropaniculatusA. K. Monro & Staff.; three new combinations are proposed: E. arachoides (Dieterle) A. K. Monro & Staff., E. gemellus(DC.) A. K. Monro & Staff., and E. glutinosus (Cogn.) A. K. Monro & Staff.; and E. floribundus (Cogn.) Rose is reducedto synonymy of E. pubescens (Benth.) Rose. A nomenclatural review is presented, and the 18 species of the genusEchinopepon are listed, together with the specimens examined. Echinopepon (Cucurbitaceae) is a genus of 18New World taxa whose center of diversity is thePacific coast of Mexico at middle to high elevations(above 1000 m) in the Sierra Madre Occidental andthe Sierra Madre del Sur. While preparing accountsof Echinopepon for Flora Mesoamericana, it becameclear that this genus was in great need of nomen-clatural and systematic revision. Previous palyno-logical work on the genus (Stafford & Sutton, 1994)and systematic treatments of the family (Jeffrey,1964; Rangaswami Ayyangar, 1976) indicated thata synoptic revision of the genus based on macro-morphological and palynological observationswould be appropriate. Echinopepon is one of four genera to have beenseparated from the genus Sicyos L. as originallyproposed in Hortus Cliffortianus in 1737 (Stocking,1955). In 1840, Torrey and Gray formed a separategenus of the New World taxa in the Linnaean Si-cyos, which they named Echinocystis. Over the nextdecade Echinocystis was divided into three sec-tions, Echinocystis ("Euechinocystis"), Echinopepon,and Marah (Cogniaux, 1877; Cogniaux, 1881),which were later recognized at generic rank byWatson (1887, in which he referred to Marah Kel-logg under the synonym: Megarrhiza Torr.). Despite further papers on the nomenclature andtaxonomic status of Echinopepon (Watson, 1889;Rose, 1897; Stocking, 1955), the genus has notbeen comprehensively reviewed since 1881, whenCogniaux treated it as a section of Echinocystis.GENERAL MORPHOLOGY The principal characters used to classify subfam-ilies, tribes, and subtribes in the family Cucurbi-taceae relate to the pistil, stamens, tendrils, andpollen (Cogniaux, 1877; Jeffrey, 1990). Within thetribe Sicyeae, anther arrangement, the dispositionof the ovules within the ovary, fruit and seed mor-phology, and the branching of tendrils have beenused to define the genera (Jeffrey, 1990). Naudin(1866) defined Echinopepon as monoecious, with 5-6-merous flowers, having three fused stamens (oneunilocular and two bilocular), a unilocular ovarybearing 8-10 ovules, a 2-chambered, coriaceous,cylindrical fruit possessing a dehiscent, apicaloperculum, and seeds that are ovoid-compressedand corrugate. Within the genus Echinopepon itself, inflores-cence disposition, flower size, the disposition of theanther thecae, the relative length of the corollalobes to the hypanthium, and fruit size, shape, andspine-length have ail been used to distinguish taxa(Naudin, 1866; Cogniaux, 1877; Rose, 1897; Wat-son, 1889). ' We thank Helen Greenop for the botanical drawings, Lourdes Rico (K) for help with Mexican localities, CarolFurness (K) for pollen samples of Echinopepon jaliscanus, Philipe Morat for a warm reception at P, Charlie Jarvis (BM)for help with nomenclature, Norman Robson (BM) for help with the Latin diagnoses, Bob Press (BM), Sandra Knapp(BM), and Mary Gibby (BM) for help with the manuscript, and the following herbaria for the loan of reference material:B, BR, F, GH, GOET, MA, MO, NY, P, and US. 2 Department of Botany, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. ANN. MISSOURI BOT. GARD. 85: 257-272. 1998.