Discovery of the Male of Parabuthus muelleri, and Implications for the Phylogeny of Parabuthus (Scorpiones: Buthidae)

24 Pages·2003·0.89 MB·English

by  Lorenzo Prendini

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PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3408, 24 pp., 7 figures, 4 tables May 22, 2003
Discovery of the Male of Parabuthus muelleri,
and Implications for the Phylogeny of Parabuthus
(Scorpiones: Buthidae)
LORENZO PRENDINI1
ABSTRACT
The male of Parabuthus muelleri Prendini, 2000 is described, based on a specimendiscov-
eredintheAlexisHaringtonScorpionCollection(recentlyacquiredbytheAmericanMuseum
of Natural History). This is only the third known specimen of P. muelleri. The holotype and
paratype are both female. The male presents several character states, including the lobate
condition of the pectinal proximal median lamella and pedipalp chelae that are notincrassate,
that are uncommon in male Parabuthus Pocock, 1890. These character states, previously
scored with missing entries in a cladistic character matrix for Parabuthus species, are now
added and a reanalysis of Parabuthus phylogeny, resulting in new insights about the phylo-
genetic position of P. muelleri, is presented. Lectotypes are designated for four northeastern
African species of Parabuthus.
INTRODUCTION and8speciesoccurringinnortheastAfricaand
the Arabian Peninsula (Prendini, 2001a). All
Parabuthus Pocock, 1890 is an exclusively but six of the southern African species have
Old World genus of scorpions, 1 of 82 genera been reported from Namibia (Lamoral, 1979),
in the diverse, cosmopolitan family Buthidae with four being endemic to that country, of
(Fet and Lowe, 2000; Kovaˇr´ık, 2001, 2002). which P. muelleri Prendini, 2000 is the most
The genus displays a classic ‘‘arid corridor’’ recent addition.
pattern of distribution (Balinsky, 1962), with At the time of its description, P. muelleri
20 species occurring in southwestern Africa wasknownfromonlytwoadultfemalespec-
1Assistant Curator, Division of Invertebrate Zoology, American Museum of Natural History. e-mail: lorenzo@
amnh.org
Copyright(cid:113)AmericanMuseumofNaturalHistory2003 ISSN0003-0082
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2 AMERICAN MUSEUM NOVITATES NO. 3408
imens.Athoroughsearchthroughthecollec- digital imaging system. Measurements were
tions of the National Museum of Namibia made with Mitutoyo digital calipers. Color
(Windhoek), the South African Museum designation follows Smithe (1974, 1975,
(Cape Town), the Transvaal Museum (Pre- 1981), trichobothrial notation follows Va-
toria), and the Natal Museum (Pietermaritz- chon(1974),andmensurationfollowsStahn-
burg), all with extensive holdings of sorted ke (1970) and Lamoral (1979). Morphologi-
and unsorted Parabuthus material from cal terminology follows Couzijn (1976) for
southern Africa, revealed no additionalspec- the segmentation of legs, Hjelle (1990) and
imens. The absence of adult male specimens Sissom (1990) for the segmentation of ped-
prevented several important characters per- ipalps, and Stahnke (1970), Lamoral (1979),
taining to sexual dimorphism and the male Sissom (1990), and Prendini (2000a, 2001a)
genitalia from being described for P. muel- for remaining features.
leri, and these characters also had to be As in previous papers (Prendini, 2000a,
scored with missing entries in a previously 2001a), the terms used by other authors on
published cladistic character matrix for Par- the southern African scorpion fauna (East-
abuthus species (Prendini, 2001a). wood, 1977; Lamoral, 1977, 1979; Fitz-
A single adult male specimen has since Patrick, 1994) for certain metasomal carinae
been discovered in the Alexis Harington have been replaced with terms implyingspe-
ScorpionCollection(recentlyacquiredbythe cific homology statements between carinae
American Museum of Natural History).This on segment V and those on the preceding
isonlythethirdknownspecimenofP.muel- segments. The term ‘‘ventral’’ (segments I–
leri, but it is sufficient to update the diag- V)isreplacedwith‘‘ventrosubmedian’’(seg-
nosis and description ofthespecies,andpro- ments I–IV only) and ‘‘ventromedian’’ (seg-
vides additional diagnostic characters to dis- ment V only) and the terms ‘‘dorsal’’ (seg-
tinguishitfromthesisterspecies,P.capensis ments I–IV only) and ‘‘dorsal accessory’’
(Ehrenberg, 1831). The male specimen pre- (segment V only) are replaced with ‘‘dorso-
sents several character states, including the submedian’’.
lobateconditionofthepectinalproximalme-
dian lamella and pedipalp chelae that are not Cladistic Analysis
incrassate, that are uncommon in male Par-
abuthus. These character states are now add- The present analysis is based on the pre-
ed to the cladistic character matrix for Par- viously published morphological data matrix
abuthus species (Prendini, 2001a), and a re- for relationships among the species of Par-
analysis of Parabuthus phylogeny, resulting abuthus (Prendini, 2001a), to which the
in new insights about the phylogenetic po- states of characters 9–12, 17, and 23, previ-
sition of P. muelleri, is presented. ously scored with missing entries for the
male of P. muelleri, have now been added
MATERIALS AND METHODS (table 1; appendix 2). The matrix comprises
51 characters, 9 coded into multistates and
Material, Photography, and Terminology
44 coded into binary states, scored for 27
The single adult male specimen of P. species. Multistate characters were treatedas
muelleri originates from the Alexis Haring- unordered, i.e., nonadditive (Fitch, 1971).
ton Scorpion Collection (AH), which is now Trees were rooted using the outgroup
deposited in the American Museum of Nat- method (Watrous and Wheeler, 1981; Farris,
ural History (AMNH). Consult appendix 1 1982; Nixon and Carpenter, 1993). As in the
for the repositories of other material exam- previous analysis, an exemplar species from
ined for the cladistic analysis, where the full each of two Afrotropical buthid genera,
collection data (previously unpublished) are Grosphus Simon, 1888, from Madagascar,
provided and lectotypes designated for four and Uroplectes Peters, 1861, from southern
northeastern African species. and central Africa, were included as out-
Photographs of P. muelleri were taken in grouptaxaonthebasisofmorphologicaland
visible light as well as under long-wave ul- molecular evidence that these genera are
traviolet light using a Microptics ML1000 most closely related to Parabuthus (Pocock,
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TABLE1
Distribution of 53 Characters Among 25 Species of the Genus Parabuthus Pocock, 1890
The first two taxa are outgroups. Refer to appendix 1 for character list. Character states are scored 0
to 2, ? (unknown), – (inapplicable) or * (polymorphic).
1890; Kraepelin, 1908; Werner, 1934; Pren- (hold 10,000 trees in memory; hold 10 start-
dini and Wheeler, in prep.). ing trees in memory; perform TBR branch-
Character data were edited, cladograms swapping on 100 random-addition repli-
prepared, and character optimizations con- cates). Additional swapping on up to 1000
ductedusingWinClada,vers.0.9.9(cid:49)(Nixon, trees that are up to 5% longer than the short-
1999). Ambiguous optimizations were re- est trees (command jump 50;) was per-
solved using accelerated transformation formed to help the swapper move between
(ACCTRAN) or Farris optimization, which multiple local optima (‘‘islands’’sensuMad-
favors reversals over parallelisms to explain dison, 1991). Finally, trees found with this
homoplasy(Farris,1970;SwoffordandMad- command were again swapped with TBR,
dison, 1987, 1992) and therefore maximizes using the command max*; to retain onlyop-
homology (Griswold et al., 1998). Three au- timal trees.
tapomorphies(characters4,21,and50)were Successive approximations character
excluded from all analyses; hence, tree sta- weighting (Farris, 1969) and implied char-
tistics are calculated from phylogenetically acter weighting (Goloboff, 1993, 1995) were
informative characters only (Bryant, 1995). conducted to assess the effects of weighting
Characters were not weighted a priori. against homoplasious characters, and the re-
Analyses with equal weighting were con- sultant topologies were compared with the
ducted using NONA vers. 2.0 (Goloboff, topology obtained by analysis with equal
1997a), according to thefollowingcommand weights (see Prendini, 2000b, 2001a). Suc-
sequence: hold10000; hold/10; mult*100; cessive weighting, using the squared consis-
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TABLE2
Summary of Statistical and Topological Diferences Among the Most Parsimonious Trees (MPTs)
MPTs were obtained by analysis with equal weights (EW), successive weights (SW), and implied
weights (IW) with six values for the concavity constant (k), arranged in order of decreasing fitness.
Unweighted length is reported for the SW tree. Letters A and B refer to alternative topologies for
node A (fig. 1).
tency index (CI) as a weighting function uesfortheconcavityconstantweremoderate
(Goloboff, 1991), was implemented with to mild (i.e., k (cid:53) 3–6; table 2). Although
NONA by invoking the swt.run file (com- topologically identical, the MPTs obtained
mand sequence: run swt.run hold10000; by the analyses with implied weights were
hold/10; mult*100; jump50; max*;). Pee- 3–7% fitter than the MPTs obtained by anal-
Wee version 2.6 (Goloboff, 1997b) was used ysis with equal weights, while the MPT re-
for analyses with implied weighting, apply- trievedunderk(cid:53)5wasalsoonestepshorter.
ing the command sequence:hold1000;hold/ In contrast, under strong concavity (k (cid:53) 1–
10; mult*100; jump50; max*;. Analyses 2), analyses with implied weights located
with implied weighting investigated the use two MPTs, each three steps longer and 5–
of six values for the concavity constant, k, 12% less fit than the MPTs obtainedbyanal-
spanning the input range permitted by Pee- ysis with equal weights(table2).Thesetrees
Wee (command: conc N;). differed from the topology in figure 1 with
The relative degree of support for each respect to the species comprising node ‘‘A’’,
node in the tree obtained with equal weight- for which the alternative arrangements were
ing was assessed with branch-support or de-
asfollows:(P.mossambicensis(P.kraepelini
cay indices (Bremer, 1988, 1994; Donoghue ((P. raudus (cid:49) P. schlechteri) ((P. transvaal-
et al., 1992). Branch support indices up to icus (cid:49) P. villosus) (P. capensis (P. muelleri
five extra steps (setting the maximum num- (P. calvus (cid:49) P. pallidus (cid:49) P. planicau-
ber of trees held in memory to 10,000) were
da))))))); (P. mossambicensis (P. kraepelini
calculated with NONA by means of the fol- ((P. raudus (cid:49) P. schlechteri) (P. transvaal-
lowing command sequence: h10000; bsup-
icus (P. villosus (P. capensis(P.muelleri(P.
port 5;. calvus (cid:49) P. pallidus (cid:49) P. planicauda)))))))).
The MPTs obtained by analysis with im-
RESULTS AND DISCUSSION plied weights under k (cid:53) 1–2 are longer and
Analysis of the 50 informative characters less fit than the MPTs obtained by the re-
inNONAlocatedasinglemostparsimonious maining analyses, and hence they are consid-
tree (MPT) with equal weights (table 2; fig. ered to be suboptimal. The alternative topol-
1). The same topology was retrieved in the ogy, obtained by weighting regimes thatmin-
analysis with successive weights and also in imizedlengthaswellasthosethatmaximized
the analyses with implied weights when val- fit (table 2), is instead regarded as optimal.
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Unambiguously optimized synapomorphies TYPE MATERIAL: Holotype (cid:47) (NMNW
are indicated on this topology in figure 1, 1854), Namibia: Hardap Region: Maltaho¨he
whichalsoprovidesbranchsupportvaluesfor District: Farm Onis 8, 82 km from Sesriem
nodes. The length, fit (f), consistencyindices, to Naukluft, 24(cid:56)22.46(cid:57)S, 16(cid:56)13.17(cid:57)E, 1260
i
retentionindices,andfinalsuccessiveweights m, 7.i.1998, L. Prendini and E. Scott. Para-
of informative characters on thistopologyare type (cid:47) (SAMC C4514), Namibia: KarasRe-
listed in table 3. gion:Lu¨deritzDistrict:FarmPlateau38,near
As might be expected, the arrangement of Aus, 26(cid:56)40.62(cid:57)S, 16(cid:56)31.85(cid:57)E, 1550 m,
relationships among the species of Parabu- 30.xii.1997, L. Prendini and E. Scott.
thus retrieved in the present analyses is al- DIAGNOSIS: Parabuthus muelleri falls in a
most identical to that obtained previously group of species also including P. calvus, P.
(Prendini, 2001a), as are the major findings. capensis, P. pallidus, and P. planicauda.
Monophyly ofthegenusParabuthusisagain This species is morphologically most easily
supported, but monophyly of the disjunct confused with P. capensis, with which it
southern African versus northeasternAfrican shares the following combination of charac-
and Arabian species is not. The optimal to- ters: metasomal segments I and II, stridula-
pology presented here differs from that pub- tory region extended anteriorly beyond an-
lished previously only in relationships terodorsal edge of segment, giving a steplike
amongthefivespeciescomprisingnode‘‘B’’ appearance in lateral aspect; metasomal seg-
(fig. 1): P. calvus, P. capensis, P. muelleri, ments II–IV, dorsosubmedian carinae with
P. pallidus, and P. planicauda. Previously, distal spiniform granules more pronounced
the relationships among these species were than preceding granules; metasomalsegment
retrieved as follows by the majority of anal- IV, dorsosubmedian carinae mediallydiscon-
yses, including those deemed optimal: ((P. tinuous,medianlateralcarinacontinuousand
capensis (cid:49) P. muelleri) (P. pallidus (P. cal- distinct; metasomal segment V, dorsosub-
vus (cid:49) P. planicauda))). All previous analy- median carinaedistinctwithsharp,spiniform
sessupportedthe(P.capensis(cid:49)P.muelleri) or subspiniform granules, and dorsolateral
group. In contrast, all present analyses re- carinae distally obsolete. Parabuthus muel-
trieved the following arrangement of these leri and P. capensis can be separated from
species: (P. capensis (P. muelleri (P. calvus all other Parabuthus on the basis of the fol-
(cid:49) P. pallidus (cid:49) P. planicauda))). Thus, lowing character: metasomal segmentII,and
whereas a sister-group relationship between to a lesser extentIII, withposterodorsaledge
P. capensisand P.muelleriwasidentifiedby elevated and slightly curved forward medi-
previous analyses, the addition of six char- ally, forming a subtriangular V-shape.
acter states for the male of P. muelleri indi- Although morphologically similar, P.
cates that this species actually shares a more muelleri can be separated from P. capensis
recent common ancestor with P. calvus, P. by several characters. The movable finger of
pallidus, and P. planicauda than with P. ca- the pedipalp chela (adult maleand female)is
pensis. The sister-grouprelationshipbetween curved ventrally in P. muelleri, such that the
P. calvus and P. planicauda, retrieved by proximal dentate margin is distinctly emar-
most,butnotallpreviousanalyses,isnolon- ginate when the fingers are closed (i.e., a
ger supported either. proximal ‘‘gap’’ is evident). The emarginate
condition occurs in the male of several Par-
SYSTEMATICS abuthus species (e.g., P. granulatus, P. ka-
FAMILYBUTHIDAEC. L.KOCH,1837 laharicus,andP.laevifrons),butitisuncom-
GENUSPARABUTHUSPOCOCK,1890 mon in female Parabuthus, and does not oc-
Parabuthus muelleri Prendini, 2000 cur in the male or female of P. capensis. In
addition, P. muelleri has a more slender me-
Parabuthus muelleri Prendini, 2000a: tasoma, in which the median width:length
32–38, percentage for metasomal segments I–V (n
figs. 1–9, table 2. (cid:53) 3) is 80.5% (75–86%), 78% (75–81%),
Parabuthus muelleri:Prendini,2001a:17;2001b: 76% (72–80%), 69.5% (65–74%), and 55%
137. (53–57%), compared with the metasoma of
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P. capensis, in which the median width: ther in the description of sexualdimorphism,
length percentage (n (cid:53) 6) is 86% (77–95%), below.
73% (78–88%), 92% (79–105%), 73% (67– DESCRIPTION: The following description of
79%), and 58% (53–63%). Metasomal seg- the male (AMNH [AH 3991]) supplements
ment III is usually broader than segments I the previous descriptions (Prendini, 2000a)
and II in P. capensis, but this is not the case of the holotype female (NMNW 1854) and
inP.muelleri.Parabuthusmuelleriisfurther paratype female (SAMC C4514).
distinguishedbytheunusualshapeofthetel- Color: Carapace, chelicerae, tergites, ster-
son, which differs from all known Parabu- nites, and metasomal segments I–III: Cinna-
thus species in the presence of a distal mon no. 123A. Metasomal segments IV, V
‘‘bulge’’ and a very short, sharply curved and telson: Burnt Sienna no. 132. Pedipalps
aculeus. The median percentage of aculeus and legs: Clay Color no. 123B. Pectines:
length:telson length in P. muelleri (n (cid:53) 3) is Chamois no. 123D. Metasomal segments IV,
30% (26–34%), compared with 39% (36– V and telson are distinctly darker than seg-
42%)inP.capensis(n(cid:53)6).Thetwospecies ments I–III, whereas pedipalps and legs are
may also usually be distinguished by the rel- distinctly paler than carapace, mesosoma,
metasoma, and telson (figs. 2, 3).
ative positions of the trichobothria on the
Carapace: Carapace with sulci, without
fixed finger of the chela: eb and esb are lo-
carinae, and covered entirely by uniform,
catedproximaltothebasaldentatemarginof
coarse granulation, becoming coarser on in-
the fixed finger in P. muelleri, whereas eb is
terocular and posterolateral surfaces. Anteri-
located proximal to thebasaldentatemargin,
or margin of carapace procurved; posterior
and esb is located distal to it, in P. capensis.
margin straight. Five pairs of lateral ocelli.
However, this character has been foundtobe
Medianocelliconsiderablylargerthanlateral
polymorphic in P. capensis: in populations
ocelli, situated anteromedially (fig. 4). Ocu-
from the eastern part of the distributional
lar tubercle with pair of smooth superciliary
range,esbisalsolocatedproximaltothebas-
carinae, protruding slightly above median
al dentate margin (Prendini, 2000a).
ocelli. Anteromedian furrow shallow; pos-
Two characters of the newly described
teromedian furrow shallow anteriorly, be-
male can also be used to separateP.muelleri
comingdeeperposteriorly;posterolateralfur-
from P. capensis, notably the lobate condi-
rows shallow, wide, curved; posteromarginal
tion of the pectinal proximal median lamella
furrow narrow, deep.
and pedipalp chelae that are not incrassate
Chelicerae: Movable finger with distalex-
(i.e.,notsexuallydimorphic).Theabsenceof ternal and distal internal teeth equal, oppos-
sexual dimorphism of the pedipalp chelae is able. Ventral aspect of fingers and manus
a particularly obvious diagnostic difference with long, dense macrosetae. Fixed finger
between P. muelleri and P. capensis, in with a pair of denticles on the ventral sur-
which the pedipalp chelae are markedly di- face.
morphic (the pedipalp chela manus of the Sternum: Subtriangular (fig. 3). Median
maleisincrassate,whereasthatofthefemale longitudinal furrow Y-shaped, shallow ante-
isslender).Bothcharactersarediscussedfur- riorly, deep and narrow posteriorly.
‹
Fig. 1. The optimal tree obtained by analysis under weighting regimes that maximized fit and min-
imized length. This topology was retrieved by analyses with equal weights, successive weights, and
implied weights under k (cid:53) 3–6 (table 2). Zero-length branches are collapsed. This topology also cor-
responds to the majority rule ((cid:46)50%) consensus of MPTs obtained by the eight analyses in which
weighting regime and multistate character transformation were varied (table 2). Solid bars indicate
uniquely derived apomorphic character states, whereas empty bars indicate parallel derivations of apo-
morphic states under ACCTRAN optimization. The numberaboveeachbargivesthecharacternumber,
whereasthenumberbelowgivesthecharacterstate.Branch-supportvaluesofnodesareprovidedbelow
branches. Refer to appendix 2 for character descriptions.
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TABLE3
Length (steps), Fit (f), Consistency Indices (CIs), and Retention Indices (RIs) of 50 Informative
i
Characters Scored Among 25 Species of the Genus Parabuthus Pocock, 1890
Final weights obtained with succesive weighting (SW) are also reported.
Pedipalps: Pedipalps covered in short ma- and a large proximal granule, flanked by an
crosetae (figs. 7–9). Femur finely and uni- inner and an outer accessory granule; chela
formlygranular;pentacarinate,allcarinaedis- fingers each with a terminal denticle.
tinct, granular, except for internomedian ca- Trichobothria: Orthobothriotaxic, type A,
rina, comprising spiniform granules. Patella (cid:97) configuration, with the following segment
finely and uniformly granular; carinae absent totals (figs. 7–12): femur, 11 (5 dorsal, 4 in-
or obsolete; dorsointernal and ventrointernal ternal, 2 external), patella, 13 (5 dorsal, 1
carinae each comprising a row of granules internal, 7 external), and chela, 15 (8 manus,
proximally; internomedian carina comprising 7 fixed finger). Total numberoftrichobothria
a large spiniform granule, proximally, and a perpedipalp,39.Chelawitheblocatedprox-
few smaller granules, distally. Chela smooth; imal to basal dentate margin of fixed finger
carinae absent. Chela short, slender, length and esb located just distal; dt almost level
along ventroexternal carina 28% greater than with et; db equidistant between est and esb.
chela width and 30% greater than chela Patella with esb slightly distal to esb . Fe-
2 1
height; length of movable finger 45% greater mur with d on proximointernal side of dor-
2
thanlengthalongventroexternalcarina.Chela sointernal carina; d distal to d ; d equidis-
3 2 4
fixedfingerslightlycurveddorsallyandmov- tant between d and d .
3 5
ablefinger slightlycurvedventrally,suchthat Mesosoma: Pre-tergites smooth and shiny,
proximaldentatemarginemarginatewhenfin- granular along posterior margins. Post-ter-
gers are closed (fig. 7). Dentate margins of gites entirely coarsely granular, granulation
chela fingers each with 11 oblique granular becoming coarserdistally(fig.2);I–VIIeach
rows, each comprising 4–6 small granules with a weakly developed, granular median
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Figs.2,3. ParabuthusmuelleriPrendini,2000,male(AMNH[AH3991]),habitus.2.Dorsalaspect.
3. Ventral aspect. Scale bar (cid:53) 5 mm.
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