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NEW PANAMANTHUS, A Job Kuijt MONOTYPIC GENUS OF NEOTROPICAL LORANTHACEAE' Abstract The monotypic genus Panamanthus Kuijt (P. panamensis (Rizz.) Kuijt) proposed to accommodate the Panamanian is & mistletoe previously known as Struthanthus panamensis Barlow Wiens; an expanded and (Rizz.) description Panamanthus illustrations are provided. It is suggested that is related to Gaiadendron G. Don, another monotypic genus found approximately same in the ecological zone. The known mistletoe species presently as Stru- acters prohibit placement in any of the first three. & thanthas panamensis (Rizz.) Barlow Wiens was Dendropemon often has pedunculate monads, and member originally described as a of the genus the bracteoles are sometimes fused in a cupulate Phrygilanthus (Rizzini, 1960). As made clear by fashion. The anthers of Rizzini's species are nearly & Barlow Wiens Dendropemon (1973), Eichler's genus Phry- dorsifixed, but has unequivocally ^//r/n//?w5 cannot be maintained for systematic and basifixed anthers. Also, the filaments of Dendro- The pemon nomenclatural reasons. only species of Phry- are laterally excavated, a feature shared gilanthus that Rizzini mentioned as a possible with the continental Phthirusa but not with other rel- new The ative to his species has subsequently been genera. stem roots of Rizzini's species have vemoyed to Psittacanthus {Psittacanthus palmeri no equivalent in Dendropemon, and would be it & & Watson) Barlow Wiens; Barlow Wiens, extraordinary have Ca- (S. to a low-elevation, strictly 1973). Rizzini's species was transferred to Stru- ribbean genus represented by a single species at & thanthas by Barlow Wiens (1973), although high elevations in Chiriqui. No one has suggested these authors did recognize its unusual nature. affinities to Dendropemon, however, which clear- is There are two major morphological features in ly very closely related to Phthirusa and probably which Rizzini's species differs from other known to Oryctanthus as well; the species would clearly all much species of Struthanthus, First, has bisexual flow- be out of place there at least as as has it it ers, whereas the other species are strictly dioecious. been in Struthanthus, The disposition of S. pan- Second, the inflorescence consistently monadic, amensis has been a continual problem since is its and while that of the other species basically or entirely description, here propose that the species be is I triadic. Also, the prophyllar bracteoles associated treated as a monotypic genus with possible, but with each flower are fused above the flower so as rather distant affinities to another monotypic genus known same to hide the entire ovary, a feature not in found in the ecological zone, Gaiaden- i.e., d any other neotropical continental Loranthaceae. ron New The two features are elsewhere the in first World known Oryctanthus Oryc- Panamanthus only in Eichl., Panaman- Kuijt, gen. nov. TYPE: Van Maracanthus tina Tiegh., Kuijt, and the Ca- thus panamensis comb. (Rizz.) Kuijt, nov. Dendropemon ribbean Blume, and would strict logic Phrygilanthus panamensis Ann. Rizz., Missouri Bot. Gard. placement one necessitate of Rizzini's species in of 270-272. 47: 1960. Of those genera. these, only the last genus needs & Struthanthus panamensis Barlow Wiens, (Rizz.) Brit- to be considered, as various other structural char- tonia 25: 39. 1973. acknowledge continuing financial support from the Natural Sciences and Engineering Research Council of I ' Canada. Karel U. Kramer of Zurich kindly provided the Latin diagnosis. Several collectors have made special efforts in Chiriquj to collect this elusive species, and several curators have extended special courtesies; these efforts have added significant substance to this presentation. ~ Missouri Botanical Garden; Mailing address: Department of Biology, University of Victoria, Victoria, British V8W Columbia, Canada 2Y2. Ann. Missouri Bot. Gard, 78: 172-176. 1991. Volume Number 78, 173 Kuijt 1 1991 Panamanthus mm — — — Panamanthus Figure panamensis. Monad 1. a. Habit of plant in fruit. b. Inflorescence in bud. c. in bud & van der Werff Herrera 6330, LEA; McPherson 9380, LEA). (a, b, c. Inflorescentia indeterminata. monadica. bracteis nu- with occasional formed from epicortical roots merosis caducis suffulta; flores hermaphroditi bracteolae cm branches; internodes to 6 long, somewhat^quad- coalitae, cupulam iormantes et ovarium occultantes. ^, . when becommg rangular young, soon Leaves terete. m Scandent x cm plants to 3 diam., with rather to 14 7 cm, decussate; petiole 1.5 long, m straight, pendant branches or more in length, blade thin, with evident pinnate venation, base 1 Annals the 174 of Garden Missouri Botanical mm '.( » k^. J.! **• i V b I i' •« ' ' > 'J*; ^* :-. i. ^ - t /* A*- • « E E 'd ft- C * 4 t * f d cm — — Figure 2. Panamanthus panamensis. a. Open flower, the two fused bracteoles visible below. b. Longitudinal — — — Young mature stamen shown Base Mature section of bud, with separately, dorsal view. c. of flower. d. fruit. e. — inflorescence bud covered by scale leaves. Base of infructescence with old persistent scale leaves (a-c, still f. & mibur DUKE; DUKE). McPherson 9380, LEA; 13109, Luteyn 3786, Teeri d, e, f, Volume Number 78, 175 1 Kuijt 1991 Panamanthus truncate or very obtuse, apex contracted con- into slope of Volcan Baru, starting along impassable road for- cm Boque spicuous, slender to .5 long. Inflorescences tail 1 1.750-1.900 m, McPherson 11343 (LEA, MO); 2-4 cm vicinity somewhat quadrangular, at anthesis, race- of Cerro Punta, above Guadalupe, forested slopes above mose, indeterminate, in small axillary clusters, in- STRI 2,300-2,450 m, McPherson 9380 cabin, (LEA, subtended by caducous dividually several pairs of MO). scale leaves and set in a craterlike corky rim, Discussion inflorescence peduncle very (2-3 mm), short fol- 6-8 monad lowed by pairs of monads; peduncle The several structural peculiarities of Pana- mm 2-2.5 long, fused along its length with a bract manthus panamensLS when outlined above, taken mm extending 4 beyond and sharply acute; brac- aggregate, sharply from in distinguish other it all mm % teoles ca. 2 long, fused along the lower of neotropical Loranthaceae. In terms of the inflo- where their length investing the nearly hidden ova- rescence and associated features, the Australian mm the acute both ry, free, tips 1 long; bracteoles genus Atkinsonia would seem to be the most sim- and bracts with conspicuous whitish margins when However, such an could only be ilar. affinity re- 6-9 cm dry; infrutescence elongating ma- to at mote, as would be qualified by the it strictly ter- Flowers hexamerous, turity. pale yellow, with pleas- restrial habit of that genus, and the various primitive ant odor, the petals very slightly dimorphic; mature features associated with in the seedling stages at it mm 8-9 mm) bud above long, thickest (2 just the least some of which we can safely extrapolate from middle, with prominently acute ovary very tip; those of the closely related Gaiadendron (Kuijt, mm), short calyculus inconspicuous, with Any slightly 1963, (1 1965). affinity of this sort, therefore, undulating rim; anthers dimorphic, basifixed or can only be tenuous. nearly so, lower ones reaching to top of stigma, known Unfortunately, nothing about the chro- is upper ones almost entirely beyond; pollen sacs four, mosomes Panamanthus of panamensis, and it is long and slender, connective extending beyond as precisely here that significant information might mm), a small spur; filament extremely short (0.5 be expected. The primitive of Atkinsonia, trio downward continuing as a long buttress on petal Gaiadendron, and Nuytsia number shares a basic Pollen isopolar, diplosyndemicolpate, glabrate. Style of n 12, the chromosomes being very small for mm & straight, ca. 5 long, terete below but com- Loranthaceae (Barlow Wiens, 1971); con- in pressed by the anthers above; stigma undifferen- trast, the small-flowered neotropical genera of Lo- sometimes Nectary prom- tiated, slightly oblique. ranthaceae Struthanthus have like n the 8, somewhat inent, with undulating surface. Fruit chromosomes being among known the largest in cm baccate, nearly diam., spherical, yellowish 1 the angiosperms (Wiens, 1964). orange, its calyculus inconspicuous, viscin tissue The caducous inflorescence bracts referred to mm Embryo insignificant. small (2 long), slender, in the above diagnosis have not, as far as am I lacking a swollen radicular apex maturity. at aware, been mentioned in the literature, and con- Apparently a Chiriqui endemic, but be looked to trast strongly to other species of Struthanthus all for also in nearby Costa Rica, especially in the except two or three species that are clearly not San region east of Vito. related Panamanthus panamensis, such to as S. leptostachyus (Kuntze) G. Don. Similarly incon- Materials examined. Panama. CHlRlQUf: Boquete spicuous and caducous bracts are normal Gaia- in Bajo Chorro, 6,000 Davidson 431 District, rainforest, ft., may (holotype, US; isotypes, F, GH), 392 (F not seen); cloud dendron, where they occasionally become forest, northeastern ridge leading to Cerro Horqueta, elongated, and and foliar, persistent (pers. obs.), 1,800-1,900 m, Luteyn 3786 (DUKE, Cerro Colora- F); also in Atkinsonia, where they are always per- km N do, cloud forest 50 of San Felix on the continental & sistent (Barlow, 1966; Kuijt, 1981). divide, 1,200-1,500 m, Mori Dressier 7825 (MO); The Panamanthus pollen of on trail to Cerro Horqueta, in cloud forest, 6,000-6,500 is similar especially ft.. Proctor 31935 (LL); mossy forest E of Guadalupe to that of Struthanthus oerstedii Standi. (Feuer NE & along Rio Chiriqui Viejo, about 2 mi. of Cerro Punta, 1985) Kuijt, but lacks distinctive, specialized & ridge of Cerro Respinga, Wilbur Teeri 13 109 (DJJKE); W There no features. are significant similarities with km disturbed cloud forest about 8 of Cerro Punta, in Gaiadendron & the primitive trio" of monotypic 6,100-6,400 Almeda the vicinity of Las Nubes, ''' ft., Nakai 3536 (CAS, LEA); along old road from Boquete genera which, however, shows extreme palynolog- N to Cerro Punta on cloud forest trail up to the slope of ical contrasts amone component eenera, as be- its Volcan Baru, 1,750-1,900 m, 8°50'N, 82°30'W, Al- & tween Nuytsia and Atkinsonia (Feuer Kuijt, & meda, de Nevers McPherson 6166 (CAS, LEA); Distr. Thus 1980). appears again that great palyno- STRI it Bugaba, Cerro Punta, from house edge moun- to of tain across the river, 8<'52'N, 82°33'W, 2,200 m, van logical divergence is compatible with close affinities & der Werff Herrera 6330 (LEA, MO); on path up N in some mistletoe groups. 176 Annals of the Garden Missouri Botanical & L Altitudinal preferences are often consistent with- D. WiENS. 197 The cytogeography of the Taxon 291-312. loranthaceous mistletoes. 20: Thus, individual genera of neotropical mistletoes. in & 1973. The of the classification Gaiadendron punctatum tends be a subparamo to ^ ul i- ^ . c rhrygu-ai nt,nlus (= ii\Si o*tant*ihera)\ generic segregates ol . America and major species both Central in in its 26-39. Loranthaceae. 25: ^f Brittonia ^^le & Andean South America 1989). In area, (Kuijt, Feuer, M. KuijT. 1980. Fine structure of S. J. contrast, Struthanthus has strong preferences for mistletoe pollen. III. Large-flowered neotropical Lo- Amer. ranthaceae and their Australian relatives. and nowhere occurring J. low middle elevations, at 34-50. 67: Bot. Panamanthus panamen- noted the elevations for & 1985. Fine structure of mistletoe (1,200-2,450 VL m). Loranthaceae. 5J5 Small-flowered neotropical pollen. 187-212. In summary, the monotypic generic status here Ann. Missouri Bot. Gard. 72: On KuiJT, 1963. the ecology and parasitism of the proposed more adequately recognizes the unusual J. Gaiadendron punctatum Costa Rican tree mistletoe, nature of the species. In this respect might be it 927- (Ruiz Pav6n) G. Don. Canad. Bot. 41: &. J. noted most accepted genera of small-flowered that 938. neotropical Loranthaceae are more weakly sepa- 1965, The anatomy of haustoria and related . Gaiadendron Canad. Panamanthus from organs of (Loranthaceae). from each other than J. rated is 687-694. Bot. 43: For example, Phthirusa and Den- other genera. 1981. Inflorescence morphology of Loran — dropemon are separable only on the basis of triadic 1- Blumea thaceae an evolutionary synthesis. 27: monadic inflorescences, respectively. vs. 73. The morphological of Panamanthus 1989. Additional notes on the parasitism of isolation . New World Loranthaceae. Pflanzen 64: Beitr. Biol. would seem warrant status as a monotypic genus, to 115-125. however, no matter what to primitive affinities its Woodson RlzzlNl, C. T. 1960. Loranthaceae. In: R. E. same or other mistletoe genera are. At the time, & W. Panama. Ann. R. Schery (editors), Flora of Panamanthus Struthanthus may, 263-290. related to Missouri Bot. Gard. 47: if is it and monadic WiENS, D. 964. Chromosome numbers in North Amer- because of bisexual flowers inflo- 1 its Phoradendron, ican Loranthaceae (Arceuthobium, more regarded prim- rescence, be as significantly PsittacanthuSy Struthanthus). Amer. Bot. 51: J. than that genus. itive 1-6. LlTEKATURE CiTED A Barlow, B. A. 1966. revision of the Loranthaceae New of Australia and Zealand. Austral. Bot. 14: J. 421-499.