Occurrence of the Genus Microscolex (Oligochaeta, Acanthodrilidae) at Western Canary Islands

2009·0.68 MB·

by  Talavera, José Antonio

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Bonnerzoologische Beiträge Band 56 (2007) Heft 1/2 Seiten 37^1 Bonn, März2009
Occurrence of the Genus Microscolex (Oligochaeta, Acanthodrilidae)
at Western Canary Islands
José A. Talayera & Dolores I. Pérez
Faculty ofEducation (Module A), University ofLa Laguna, Tenerife, Canary Islands, Spain
Abstract. Two species ofMicroscolexare present in the western Canary Islands: M. dubius and M. phos-
phoreiis (new record for Hierroj. The latter belongs to the modern fauna ofthe Canaries and was recently
introducedby man. Both species preferto live at the basal altitude level, mainly in the highly anthropized
bandbetween 50 and 300m a.s.l. ThehabitatrangeofM.phosphoreiis israthernanow andMitsprincipal nu-
cleusofdispersionaretropical fruitplantations(papaya, avocadosandbananas); however, dubius ismo-
rediversified, itsrangeiswide,evenreachingintothenativePimiscanariensisandlaurelforestsatthemon-
tane level. Otherdataprovide evidencethat the greatest numberofspecimens and locations are onthe nort-
heastslopesofthe Canaries, asreflectedinthe firstdistributionmaps ofeachofthe islands. Thebiogeogra-
phicalaffinitieswithMacaronesiaarediscussed, alongwiththeprobable linkswithLatinAmericaasalong-
standing(500year-old)source forimportingagricultural andornamental plants intotheCanaries.
Keywords. Earthworms,Acanthodrilidae,Canaries,habitats,chorology.
1. INTRODUCTION logy ofthe genus Microscolex Rosa, 1887 in the Canary
Islandshavebeeninsufficiently studied. Therefore, inor-
The taxonomy and distribution of the Acanthodrilidae derto updateandincreasethedatawehavesampledato-
have been under study for a long time, Beddard (1895) tal of22districtsandreviewedmorethan 1550specimens,
andMichaelsen (1900)havingcompiledcomprehensive producing original iconography and the first species dis-
information on these annelids in theirmagnificent scien- tribution maps for each island (Tenerife, La Palma,
tific works. They are well known in Australasia, the Gomera and Hierro).
NeoarcticandNeotropicalregions,wheretheyarespread
overawiderangeofbothanthropizeddeforestedhabitats
andthosewithabundantvegetation (e.g. tropicalforests). 2. MATERIALAND METHODS
Thefamilyisincreasinginnumbersanddistributionarea,
asrevealedbysuccessivebiogeographicalrecordsandde- Specimenswerecollectedmainlybyqualitativesampling
scriptions of new taxa (Csuzdi & Szlávecz 2002; alongroutes ofup to one Kilometre in length, so asto in-
Fragosos 1988; Fragosos & Rec Fernandez 1994; clude a wide range ofhabitats with the greatest possible
Reynolds & Righi 1994; Zicsi & Csuzdi 1991). speciesdiversity.Ageologist'shammerwasusedfordig-
ging and specimens were picked out manually. Less fre-
%
In the Canary Islands, few acanthodrilids have been quently, 0.04 fonnalin was poured over surface areas
recorded inthe literature to date. Kraepelin (1895) cites of 100 X 50 cm, providing complementary data on spec-
Microscolex poulteni (Beddard, 1892) as presumably imen abundance. The collected earthworms wereusually
fromTenerifebutwithnodetails. Michaelsen(1900)re- transportedtothelaboratoryinsideplasticbagsalongwith
ports Microscolex dubius (Fletcher, 1887) and Mi- one Kilogramm ofearth (winter time). After washing to
croscolexphosphoreus(Duges, 1837). Later,otherauthors remove the remaining earth they were submerged in
merelycopiedthem literally(Cognetti deMarths 1906; 70 % alcohol, introduced into glass test-tubes containing
%
Baldasseroni 1912). Morerecentdatawereobtaineddur- 10 fonnalin and left for four days, then finally con-
ingdirectfieldsurveysperformedbyBouché(1973)and served in 75 % alcohol. On very warmdays andto avoid
Talayera(1992a),inparticularthoseconcerningthepres- possibleover-dryinganddesiccation,thewormswerepre-
ence ofM. dubius inbananaplantations and laurel forest pared and conserved "in situ" following the same steps.
inTenerife. Inanycase,thetaxonomy, ecologyandchoro-
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38 JoséATalayera & Dolores I. Pérez: Occurrence ofthe Genus Microscolex at Western CanaryIslands
In Talayera (1990a) keys were used to identify species. theGeneralDirectorateofUniversitiesoftheCanaryGov-
To prepare the original iconography the specimens were ernment. A minimum offive station were sampled from
placed on a sheet ofcork at the bottom ofa beaker half- each municipal district and montane localities (total 35),
%
full of70 alcoholandthedissectionwascarriedoutun- distributed as follows: 14 inTenerife, ten La Palma, four
dera binocular lens using an unsheathed razorblade and Gomera and seven Hierro.
entomological pins. The specimens examinedcame from
my own collections made during the Doctoral Thesis These districts prospected (Fig. 1) are as follows: 1 San-
(1980-1986), andfromsurveyscarriedout personally be- ta Cruz de Tenerife, 2 La Laguna, 3 Anaga, 4 El Rosario
tween 2000-2004,aspartofresearchprojectsfinancedby (MonteLaEsperanza), 5Acentejo,6Icod, 7Daute, 8Los
Fig. 1. Maps western Canary Islands showing ofmunicipal district. Green, distribution ofMicrocole.xJubius: Mallow, distribu-
tionofMicroscolexphosphoreus; Orange, distribution oftogetherspecies.
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Bonnerzoologische Beiträge 56 (2007) 39
Silos, 9 Candelaria, 10Güimar, 11 Chasna, 12Abona, 13 sent,whereassmall aracemoseseminal vesiclesnearlyal-
Arena14Adeje, 15 SantaCruzde LaPalma, 16Las Bre- waysappearinsegments 11-12.Ahydrophilic speciestol-
ñas, 17 Mazo, 18 Fuencaliente, 19 Valle de Aridane, 20 eratinghighNaconcentrations, itwasfoundathumidsites
Taburiente,21 Puntagorda, 22 Garafía(CuevadelAgua), rich in natural or artificial organic matter, and occasion-
%
23 Barlovento(LasCancelitas),24 Puntallana, 25 San Se- ally in soilswith as little as 15.5 relative humidity and
%
bastián,26Valle Gran Rey, 27 Hermigua (Cedro-Garajo- 1.1 organic matter (Buenavista, Tenerife).
nay 28 Vallehermoso (Chorros de Epina), 29 Valverde,
30 Meseta deNizdafe, 31 Frontera, 32 Dehesa 33 Julán, Habitatspectrum. It iscommon inanthropizedbiotopes
m
34 El Pinar, 35 Tajace. in the basal belt below 300 asl (gardens, parks, green-
houses,tropical fruitplantations), andalsooften found in
the medium altitude zones (400-600m) occupied by tra-
RESULTS
3. ditional agriculture, andeveninthenativeforests(Canary
pine, and laurel forest). Nevertheless, it was not found in
1550 earthworms assignable to Microscolex ditbiiis and the high mountain zones where the extensive lava fields
Microscolexphosphoreuswerestudied. Figs 1-3 showthe present a practically insumiountable natural barrier(Tei-
main anatomical-morphological characters and the pres- deNationalPark,ataltitudesover2000m).M. dubiushas
ent range ofdistribution for each species. been foundthroughoutthe northwest ofTenerife, La Pal-
maandHierro,beinglesscommononsouth-facingslopes,
Microscolexdubius (Fletcher, 1887) mainlyin areas lying leewardofthetrade-winds(Fig. 1).
Eudrilus dubius Fletcher, 1887 The presence ofthis species in Tenerife is note-worthy
Microscolex dubius Rosa, 1890 over deforested or tree-covered biotopes on northern
slopes,whereasitdiminishesgraduallytowardsthesouth,
Remarks.Themorphological variabilitybetweentheex- which explains the smaller number ofspecimens found
amined specimens is minor, except in the pigmentation there, due to the dry gritty soil, as well as to the tremen-
(different tones ofpinkish grey), and body length vary- dous impactofurban expansion associated with tourism.
ing between 30-75 cm. Male pore and prostates tubular This isrepeatedonthe south slopesofLa Palma, and Hi-
on 17. Genitalpapillaeandspermathecaearegenerallyab- erro, where the habitatrange ofM. dubius is restrictedto
valleysandravines,gardens, andavocado,tomatoandba-
nanaplantations. Italso inhabitsthe deep gorgesrunning
through Garajonay National Park (Gomera), and remote
areas of Taburiente National Park (La Palma), where it
found underneath stones and rotting trunks togetherwith
Dendrodrilus rubidus and Eisenia eiseiii.
Chorology. TENERIFE: Santa Cruz-La Laguna metro-
politanarea;above LasMercedes laurel forestandLaEs-
peranza pine forest; north-northwest slopes from the
towns ofAcentejoto Icod, Dauteand SantiagodelTeide;
south to southwest slopes from the Malpais ofCande-
laria-Valle de Güimar, to Chasna, Abona and Adeje. LA
PALMA: MetropolitanareaofSantaCruz,ruralcenterof
Mazo,andLasBreñas;northwestdistrictsbetweenthedis-
perse evergreen laurel forest of Cueva del Agua and
conifers around Puntagorda; northeast districts from the
antropized zones ofPuntallana to the undisturbed laurel
forest ofCancelitas; villages of Valle Aridane, and dis-
persedpineforestinthe southerndistrictofFuencaliente.
GOMERA: Woodlands on the central plateau ofEl Ce-
dro; agricultural areas on the northwest slopes (Valle-
hermosoandValleGranRey. HIERRO: Metropolitanarea
of Valverde; deforested soils on north slopes between
Fig. 2. Microscolex dubius. External morphology (lateral Nizdafe; El Pinar (Barranco de la Vieja, 28RBR0667));
view); General dissection oftheanteriorregion. wide forested bands in Las Dehesas, Julán, and Tajace.
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40 JoséATalayera & Dolores I. Pérez: Occurrence oftheGenus Microscolex atWestern Canary Islands
ticultural areas near the port and a few rural towns and
villages in the basal belt, where produce for export is
grownbyirrigation. Ontheotherhand,thisspeciesprefers
the pineapple, banana and avocado plantations at the
northeastern end of Hierro, whereas its presence on
Gomera is restricted to the bay ofSan Sebastián and its
suburbs, which suggestsrecentcolonizationandincipient
populations ofM.phosphoreiis with little capacity to ex-
pand towards other sites.
Chorology. TENERIFE: Parks in Santa Cruz; Botanical
GardenabovePuertode laCruz; anthropizedbiotopeson
the north slopes (from LaVictoriaofAcentejoto Los Si-
los), andsouthto southeast(Arona-Adeje).LAPALMA:
AroundtheportofSantaCruzdelaPalma;vegetablegar-
densinLasBreñasdistricts; andfragmentedlyintheValle
Aridanearea; Barlovento(northeast): Garafía,(northwest).
GOMERA: MetropolitanareaofSan Sebastián. HIERRO:
cultivated plots with non-native crops in Valverde; adja-
centhamlets with farming tradition; Dehesa (northwest);
southeastofEl Pinar(Barrancode laVieja,28RBR0667).
DISCUSSION AND CONCLUSIONS
4.
Fig. 3. Microscolexphosphoreiis. External moiphology(late-
ral view); General dissection ofthe anteriorregion.
Thisnewcontribution, asdidtheearlierstudy(Talayera
1990b, 1992b),addstotheknowledgeoftheseearthworms
Microscolexphosphoreiis (Dugés, 1837) widely distributed overtropicalAmerica andAfrica. The
Lwnbriciisphosphoreiis Dugés, 1837 family Acanthodrilidae Claus, 1880, is made up ofmore
Microscolexphosphoreiis Bouché, 1972 thantwentygenera(Sims 1980),ofwhichM/cra5co/exhas
beenabletoreachthewesternCanaryIslandsbutwithun-
Remarks. The body length between two and 5.5 cm (av- equal success, the seaports being the main entry point of
erage 3.4) is evidence that the Canary island specimens M. dubiusandM.phosphoreus.Thislatterspecieswasin-
are smaller than those described from continental areas. troduced by man in recent times, perhaps from the 18^^^
In addition, it differs from M. diibiits in its smaller size, centuryon, as a resultofthe increase in foreigntradeand
genital papillae in segment 11, penial chaetae present in imports ofexotic plants from the Caribbean colonies and
17,andapairofdiverticulatepyriform(pear-shaped)sper- LatinAmerica. HoweverthecolonizingprocessofM. du-
mathecae in segment 9. M. phosphoreiis is recorded for bius may have begun in more remote times, as shownby
the first time from Hierro. itspresencedeepwithinthenative forestsintheCanaries.
In any case, both peregrine species initially used empty
Habitat spectrum. We consider M. phosphoreiis a niches free of predators and native parasites, which
species indicative ofagricultural activity, whose pattern favoured the installation ofpioneerindividuals in a short
ofhabitats istropical fruitcropsbydrip-feedirrigationand periodoftime. Thishypothesis isinagreementwithGates
cultivatedareassubjecttotheuseoffertilizers. Itwasoc- (1972)forEuropeanlumbricidstransportedtoAmericaby
casionally found in gardenswith exotic plants and defor- man. Fig. 1 reveals somMe differences at the chorological
ested sites up to 1500 m, sharing ecological niches with Mlevel, for example that dubius is more abundant than
M. diibius. This species has a fragmentary distribution phosphoreus. In fact, the latterisrestrictedto tropical
clearly related to human action; it is present on all the fruit plantation parks and gardens with exotic plants im-
westernCanary Islands,Gomeracontributesthe leastnum- ported from America.
ber ofspecimens whereas Tenerife the greatest number,
mainly inthe northern zone in bananaandavocado plan- The habitat spectrum ofM. dubius is wider, it was even
tations. It is quite scarce in the South, where it arrived found in the native Pinns canariensis and evergreen lau-
accidentally insoiltransported fromthenorthern slopeto rel forests, where it may constitute independent popula-
improve the ground used for tropical fruit and tomatoes. tions, orotherwiseoccasionally share itsecologicalniche
In LaPalma,M.phosphoreiis isnoteworthy in somehor- with epigeous lumbricids or the endogeous species Al-
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Bonnerzoologische Beiträge 56 (2007) 41
lolobophorachlorotica Savigny, 1826belongingtothean- BeOdxdfaorrdd,,FC.lEa.re1n89d5o.nAPrMeossno7g6r9appph.oftheOrderofOligochaeta,
cient fauna ofthe Canaries. Indeed, no indications ofin- BouCHÉ,M. B. 1973.Observationsurleslombriciens(4émese-
terspecificcompetitionamongthemweredetected,which rie: X,XI). Prospection de l ile de Tenerife: Lumbricidae et
concords with what Abbot (1982) reported for Western Acanthodrihdae. Revue d' Ecologie et de Biologie du Solio
Australia. We suggest three reasons why M. dubius has 10 : 327-336.
prosperedmore thanM.phosphoreiis: ecological plastic- CoGNETTi DE MARTHS, L. 1906. Contributo allaconoscenzade-
ity, mode oftransportation, and the colonization period; l11oagídarieldofAaunnaatdoemlíleaIcsoolmepCaarnaatraied.elBloaUeUtntiivneorsdietiáMduiseTiordiinZooo21-
sinceM. dubiushas been able to adaptto a greaterdiver- (521): 1-4.
sity ofhabitats, use other dispersion routes besides the CsuzDi,Cs.&SzLÁVECZ,K. 2002.Diplocardiapatuxentissp.n.,
merelyhumanone,anditscolonizationprocessbeganlong anewearthwormspeciesfromMai-yland,NorthAmerica(Oli-
ago, as testified by finding it in montane zones with dif- gochaeta:Acanthodrihdae).AnnalesHistorico-NaturalesMu-
seoNationalis Hungarici 94: 45-51.
ficult access. All this is compatible with the possible ad-
vantagethatwouldbeprovidedbyparthenogenesisinre- Fragoso, C. 1988. Sistemática y ecología de un género nuevo
de lombriz de tieiTa (Acanthodrilini, Oligochaeta) de la sel-
cently colonized sites, where the probability offinding a va Lacandona, Chiapas, Mexico. Acta Zoológica Mexicana
mate is less. 25:1^1.
Fragoso, C. & Rojas Fernández, P. 1994. Earthworms from
Kraepelin (1895) in his naturalist study cites Mi- southeastern Mexico. New Acanthodrihdae genera and
croscolexpoulteni Beddard, without mentioning number species(Megascolecidae,Oligochaeta). Megadrilogica6(1):
1-12,
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Gates,G. E. 1972. Contributionstowardarevisionoftheearth-
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well as from any list ofspecies 'tobe confirmed' orcon- Kraeplein, K. 1895. Zoologische Ergebnisse einer Frühjahrs-
sideredas extinct, simply because it didnotexistnorhas Exkursion nach Madeira und den Canarischen Inseln. Ver-
itbeenintroducedintotheCanaryIslands.Wesuspectthat handlungen des naturwissenschaftlichen Vereins Hamburg
the researcher K. Kraepelin, inexpert in earthwonn tax- Hamburg 2: 6-17
Michaelsen,W. 1900. Oligochaeta. DasTierreich 10: 1-575.
onomyperformedanimprecise identification,perhapsdue Reynolds,J.&Righi,G. 1994. OnsomeearthwormsfromBe-
tothe similaritybetweenM.poulteni andM. dubius. Be- lize,CA.withthedescriptionofanewspecies(Oligochaeta,
sides this, it is unlikely that this latter peregrine species Acanthodrihdae, Glossoscolecidae and Octochaetidae).
could have been passedby unnoticed, since it is the only Megadrilogica 5 (9): 97-106.
acanthodrilid with a wide distribution in the Canary Is- Sims,R.W. 1980.Aclassificationsandthedistributionofearth-
worms,suborderLumbricina(Haplotaxida:Oligochaeta). Bul-
lands. In general the Microscolex genus is scarcely rep- letinoftheBritishMuseumNaturalHistory(Zoology)39(2):
resented in the Atlantic islands, which contrasts with its 103-124.
widecontinentalpresence. Inparticular,whencomparing Talavera,J.A. 1990a.Clavesdeidentificacióndelaslombrices
our results with those obtained in Madeira (Talayera de tierra (Annelida: Oligochaeta) de Canarias. Vieraea 18:
1996), the same is confirmed (only two species: M. du- 113-119.
bius and M. phosphoreus), showing similarities between Talavera, J.A. 1990b. Considerations about Ocneiodrilus oc-
thehabitatpreferencesanddistributionrangeofboth.The cidentalis (Oligochaeta: Ocnerodrilidae) in the Canary Is-
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thodrilids became dispersed over the basal and montane Talavera, J.A. 1992b. Octochaetidearthworms ofthe Canary
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Terhivuo (1988) suggested it as a pathway in the colo- Zicsi,A. & CsuzDi, Cs. 1991. DerersteWiederfundvonZapo-
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Western Canary Islands 37-41