A synopsis of Dryadorchis Schltr. (Orchidaceae)

4 Pages·1995·1.1 MB·

by  Schuiteman, A

BLUMEA 40 (1995) 421-424
A synopsis of Dryadorchis Schltr. (Orchidaceae)
A. Schuiteman & E.A.Christenson
Summary
Contrarytopublisheddescriptions, thepoorlyknownNew Guinea genusDryadorchisSchltr.neither
has afootless column,noran immobile labellum. The mergerofDryadorchis with Thrixspermum
Lour., asproposed by Clements, Wallace, andJones, is not justified. Chamaeanthus singularis
J.J.Sm. andSarcochilus huliorum Schuit. aretransferredtoDryadorchis. Akey tothe fourknown
species isgiven.
Introduction
Dryadorchis, a monopodial orchid(subtribe Aeridinae), is oneoftheleastknownof
allorchid genera.Itwas establishedby Schlechterin 1913withtwo species, D.bar-
bellataandD.minor,both fromPapua New Guinea.Schlechtercompared his genus
withSarcochilus, fromwhich Dryadorchis was saidto differby having acompletely
footlesscolumnandafirmlyattachedlabellum.In 1988Senghas choseD. barbellata
as thetype species, buthad nothing to addbeyond Schlechter'saccount, as he ap-
parently had not seenany material. Weagree with this lectotypification. In 1989
Clements, Wallace, and Jones reducedDryadorchis to Thrixspermum; according to
theseauthors "there is nothing ofany significance in Schlechter's description of
Dryadorchis to differentiateitfromthatof Thrixspermum. THEY ALSO LISTED Sarco-
chilusbrevirhachisUpton, aspecies describedfromAustralia, as asynonymunder
Thrixspermum barbellatum(Schltr.) Clementsetal.
Weagreewith Clementsetal. thatSarcochilus brevirhachisis conspecific with
Dryadorchis barbellata.Thisisreadily apparentfromUpton's illustrationas well as
fromdrawings kindly provided by L.A.Garay, which were basedon materialof
S. brevirhachisreceivedfromClements.We disagree, however, with themergerof
Dryadorchis with Thrixspermum. Upton's and Garay's illustrationsare much more
informativethanSchlechter'srathercrudesketches. Theformershow thatinS. bre-
virhachisthe lip is clearly articulatedwith the swollenapex ofashort but distinct
columnfoot.This is unlikethesituationfoundin Thrixspermum, wherethecolumn
footforms a singleunarticulatedstmcture whichis continuouswith thebaseofthe
lip(see Fig. 1b).ItisevidentthatinDryadorchis barbellatathelipisreally hinged to
the columnfoot in muchthe sameway as in Sarcochilus, Pterocerasetc. In these
generathe lip can easily bepulled downwardwithoutsevering theconnectionbe-
1) Rijksherbarium/Hortus Botanicus, P.O.Box 9514,2300 RALeiden,The Netherlands (forre-
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422 BLUMEA Vol. 40, No. 2, 1995
tween lipand columnfoot.In Thrixspermum, ontheotherhand,thesameactionwill
usually breakoffthelip.Moreover, in Thrixspermum thereis always a callusin the
centre oftheconcave baseofthelip;thisislacking inDryadorchis.
When describing Sarcochilus huliorum, one ofus(A.S.) pointed outthat this
species was an aberrantmemberofSarcochilus, apparently relatedtoS.singularis,
andthatthese two species might makeupa genusoftheirown. Also discussedwere
thedifferencesbetweenSarcochilus, Brachypeza, andPteroceras.Being misledby
Schlechter'serroneous description ofDryadorchis andthereductionofDryadorchis
to Thrixspermum by Clements etal., Dryadorchis was not includedin the discus-
sion. From the aboveit is quite clear, however, thatSarcochilus huliorumandS.
singularis arecongeneric withDryadorchis. Thenecessary combinationsare made
below.
Therelationships ofDryadorchis within thesubtribe Aeridinaearedifficulttoas-
sess. Withoutthebacking ofathorough cladisticanalysis statementsaboutaffinities
are largely guesswork. We donot know, forexample, whetherthecharacterstates
'flowers ephemeral' and 'liparticulatedwith thecolumnfoot' are apomorphic or
plesiomophic in theclade inwhichDryadorchis belongs. Weare convinced, how-
ever,thatasubdivison ofthesubtribe basedon thestructure ofthepollinia alone,as
frequently practised in recentliterature,oftenbrings togetherdiscordantelementsand
separatesgenerawhichmay wellbeclosely related.
DRYADORCHIS
Dryadorchis Schltr., FeddeRep.,Beih. 1 (1913)976;Senghasin Schltr.,Die Orch.,Ed. 3 (1988)
1201;Clements,Wallace & Jones,Austral. Orch. Res. 1 (1989) 144 (insyn. sub Thrixsper-
mum). —Lectotype: D. barbellata Schltr. (chosenby Senghas, I.e.).
Almost stemlessepiphytes. Leaves subfalcate, twistedatthebaseandmore orless
spreading inoneplane. Inflorescencearaceme, solitary; peduncle elongated, patent;
rachis swollen, angular, pointing downward.Flowersephemeral, appearing succes-
sively, singly or in pairs. Columnstout;foot relatively short, swollen, pubescent.
Lip hinged to the columnfoot, with shallow concavities, not spurred. Pollinia4,
subequal, in 2 globose masses (NB: D. minoris in several respects incompletely
known).
Distribution—NewGuinea(inch SchoutenArchipelago), probably endemic(see
note underD. barbellatabelow). Sealevel upto 1700m.
KEY TO THE SPECIES
1a. Upper surfaceofthelip withamedianpair oflateralkeels . 4. D.singularis
b. Uppersurfaceofthelip unadornedatthe median, smooth 2
2a. Lip withatransverse crestbetweenthelaterallobes 1. D.barbellata
b. Lip withoutatransversecrestbetweenthelaterallobes 3
3a. Sepals more than 10 mmlong 2. D. huliorum
b. Sepals less than5 mmlong 3.D. minor
A. Schuiteman & E.A. Christenson: Synopsis ofDryadorchis 423
Fig. 1.Cross sectionsthroughcolumn andlip of:a.Dryadorchis huliorum (Schuit.)Christenson &
Schuit.;b. Thrixspermumpurpurascens (Blume)Rchb.f.(DrawnbyA.Schuiteman;a: afterLeiden
cult. 31682;b: afterLeiden cult.25253).
1. Dryadorchis barbellataSchltr. — Fig. 2a, b
Dryadorchis barbellata Schltr.,FeddeRep., Beih. 1(1913)976;ibid. 21 (1928)t. 344 f. 1325;Sen-
Sghasin Schltr.,DCie Orch., Ed. 3H(1988) 1201,f. 1L025.— ThrixTspermum barbRellatum
.......................119891Schle4chte4r 18.550
(Bf), 19052(B t),PapuaNew Guinea,MadangProv., 1300 m.
Sarcochilus brevirhachisUpton,Orchadian 5(1976)24, fig. — Type:Karnaghan3(NSW,n.v.),
Australia,North Queensland,1200m.
Note—According toClementsetal. thereis considerableconfusionas tothetype
locality ofSarcochilusbrevirhachis. Although nosuch confusionisapparentfrom
Upton's article,weagreethatitis unlikelythataspecies previously knownonly from
theMadang ProvinceofPapua New Guineashouldoccur inQueensland, Australia.
2.Dryadorchis huliorum(Schuit.) Christenson&Schuit., comb.nov. —Fig. 1a,
2c, d
Sarcochilus huliorum Schuit.,Blumea 38(1994)513,f.1.— Type:Leidencult. 31682 (leg. Schui-
teman, Mulder& Vogel90-375)(L holo;K, LAE iso;spirit mat.),PapuaNew Guinea,South-
ern HighlandsProv., 1700 m.
Note— Mr.P. OrmerodandMr. J.J.Woodboth andindependently drewour at-
tOenFtionWtoHanIeCaHrliercToHlleEctYionoAfDL.ShuOlioruGmE, NEROUSLY PROVIDED
Reeve 624, Papua New Guinea, SouthernHighlands Prov., LakeKopia-
go, 1300m (AMES, CBG, E, K, L [?], LAE). TheLeiden duplicate appears to be
missing, henceour oversight.
3. Dryadorchis minorSchltr. — Fig. 2e
Dryadorchis minor Schltr.,FeddeRep.,Beih. 1(1913)977;ibid. 21(1928)t.344 f. 1326.—Type:
Schlechter 16914(B t,PapuaNew Guinea,MadangProv., 1000 m.
424 BLUMEA Vol. 40, No. 2, 1995
Fig. 2.Labelli ofDryadorchis. a,b.D. barbellata Schltr.;c, d. D. huliorum (Schuit.) Christenson
& Schuit.;e. D. minor Schltr.;f,g.D. singularis(J.J. Sm.)Christenson & Schuit. —Scalebar =
3mm(Drawnby A.Schuiteman;a, b:redrawn afteranunpublishedsketchbyGaraybased onma-
terialreceived from Clements;c, d:afterLeiden cult. 31682;e:redrawn afterSchlechter [1928];f,g:
redrawn afterJ.J.Smith[1915]).
4. Dryadorchis singularis (J.J. Sm.) Christenson & Schuit., comb. nov. —
Fig. 2f, g
Chamaeanthus singularis J.J.Sm.,Bull. Jard. Bot.BuitenzorgII, 3(1912)77. -—Sarcochilus sin-
gularis(J.J.Sm.) J.J.Sm.,Fedde Rep. 12(1913)27;Nova Guinea 12(1915)457,t. 178f.331;
ibid. 14(1929)493. —Type: Gjellerup451 (BO, n.v.),Irian Jaya,northeastern part,50 m.
Note— Alsofound on theislandofBiak(Schouten Archipelago), atsealevel.