An Example of Abnormal Carapaco-Abdominal Fusion in Neobisium aff. fuscimanum (Arachnida, Pseudoscorpiones, Neobisiidae)

2 Pages·1991·1.2 MB·English

by  Bozidar P M Curcic

1991. TheJournal ofArachnology 19:225-226
RESEARCH NOTES
AN EXAMPLE OF ABNORMAL CARAPACO-ABDOMINAL
FUSION IN NEOBISIUM AFF. FUSCIMANUM
(ARACHNIDA, PSEUDOSCORPIONES, NEOBISIIDAE)
Teratologicalphenomenainvariousrepresen- 1982). The setation oftergite I has been drasti-
tativesofthepseudoscorpionfamilyNeobisiidae callychanged,sincethenumberofsetaeisgreatly
areextremelydiverse,asshownbyCurcic(1980, increased and their distribution irregular. The
N
1989a, b), Curcic and Dimitrijevic (1984, 1985, deutonymphof fuscimanumnormallycarries
.
1986, 1990) and Curcic et al. (1981, 1983). The 6-8 setae on tergite I (Curcic 1982). Tergite II
majority of the observed malformations affect bears 3 small setae on the left, but is devoid of
theabdominalsegmentation,thuscausingeither setaeon the right. Thetergal sectionwith 6 setae
tergalorsternaldeficiencies.However,anumber otherwise found anteriorto tergite II might rep-
ofspecimenshavebeenfoundwhichexhibitvar- resent a part ofthis tergite, which perhaps had
iousaberrationsofthechelicerae,pedipalps,and been split originally into two transverse areas.
walking legs (Curcic 1980). However,itisalsopossiblethatthisdemi-tergite
Records ofcarapacal deficiencies in the Neo- may represent a supernumerary sclerite, located
bisiidae are very sparse. Only recently, an ab- betweentergitesIandII.Thisassumptionisbased
normalcarapaco-abdominaljunction(fusion)was on the presence ofan additional row ofsetae on
studiedinamaleofNeobisiumcarpaticum Beier this isolated tergal section. A similar case has
(Curcic and Dimitrijevic 1984, 1986). To our been noted in N. sylvaticum C. L. Koch (Curcic
knowledge, thisisthe onlycaseofmalformation and Dimitrijevic 1985). Altogether, fivetypes of
affectingthecarapacewhichhasbeendiscovered abnormalities have been found to affect the car-
to date. apace and abdominal tergites in this deuto-
In a collection of pseudoscorpions made at nymph: (1) partial atrophy of the carapace, (2)
Asanovac, near Zitoradja, Serbia (Yugoslavia) carapaco-abdominalfusion[symphysomery],(3)
during March 1989, one anomalous deuto- partial atrophy of tergite II, (4) the occurrence
nymph of Neobisium aff. fuscimanum (C. L. ofasupernumeraryscleriteand,(5)thealteration
Koch) was found. The specimen was obtained ofsetation in both carapace and tergites.
by sifting humus in an oak forest. In the speci- The segmental anomalies in neobisiid species
men, only the carapace and the anterior tergites mainly occur during the “maturation molt”, or
were anomalous, while the stemites and the ap- the transformation of tritonymph into adult
pendages were normal in all respects. (Curcic 1989b). Considerably fewer specimens
The purpose of this note is to describe the become aberrant when transforming from deu-
phenomenon of carapaco-abdominal fusion in tonymph into tritonymph, or from the proto-
theaberrantdeutonymph. Thecarapace and the nymph into deutonymph, as was shown by Cur-
firsttwotergites ofthis specimen areanomalous cic(1989a,b)andCurcicandDimitrijevic(1986).
(Fig. 1). The carapace lacks a chitinous section The origin ofthe malformations in this spec-
on the right posteriormargin; instead a thinand imen ofN. aff. fuscimanum is still unclear. We
transparentmembraneispresentintheareawhere assume that the genesis ofthe drastically mod-
themissingpartofthecarapacewouldotherwise ified carapaco-abdominal junction in this ex-
be found. In addition, tergite I is fused with the ample is provoked by genetic factors, especially
carapacealongitsmid-anteriorregion. Asacon- thoseaffectingthemetamerizationperiod,aswas
sequenceofthisdeficiency,thecarapacalsetation shown elsewhere by Gehring (1985) for repre-
inthisspecimenissignificantlyalteredinrelation sentatives ofvarious invertebrates.
to the normal setal complement for a deuto- We are grateful to M. R. Zlatkovic(Zitoradja)
nymph, 4 + 6 -I- 6 + (6-7) = 22-23 (Curcic for his help in collecting pseudoscorpions.
225
226 THE JOURNALOFARACHNOLOGY
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Figure \.—NeobisiumaS.fuscimanum(C. L. Koch). BozidarP.M.CurcicandRajkoN. Dimitrijevic:
Scale line = 0.5 mm. C+Tl = carapace and tergite I, Institute ofZoology, Faculty ofScience, Uni-
ST = supernumerary tergite (?), T2 = tergite II. versity of Belgrade, Studentski Trg 16, YU-
1000 Beograd, Yugoslavia.
1
LITERATURECITED
Manuscript receivedMay 1991.
Curcic, B. P. M. 1980. Accidental and teratological
changes in the family Neobisiidae (Pseudoscor-