Wubanoides uralensis (Pakhorukov 1981) - Geographic variation, mating behaviour, postembryonic development and description of a new subspecies (Araneae, Linphiidae)

2004·1.4 MB·English

by  Schikora, Hans-Bert

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Wubanoides uralensis (PAKHORUKOV 1981) -
Geographic variation, mating
behaviour, postembryonic development
and description of a new subspecies
(Araneae, Linyphiidae)
H.-B. SCHIKORA
Abstract: An overview regarding the geographic variation of taxonomic characters is given for the li-
nyphiid spider Wubanoides uralensis (PAKHORUKOV 1981). Having a distribution centre in Siberia/North
Asia, it occurs only in a few disjunct, relict-like regions in Central Europe. Compared with the paraty-
pes from the main North Asian distribution area, European specimens are taxonomically clearly dis-
tinct. Differences in habitat preference are also obvious. Hence, European populations are now being
assigned to a separate taxon at subspecific level: W. uralensis lithodytes nov. subsp. Successful ex ovo re-
arings allowed detailed descriptions of postembryonic development and courtship behaviour. Additio-
nal, preliminary observations have been carried out on some ecological aspects.
Key words: Araneae, Linyphiidae, Wubanoides uralensis, geographic variation, new subspecies, postem-
bryonic development, courtship behaviour.
Introduction Khentai-Nuruu mountains) and Mongolia
(ESKOV & MARUSIK 1992, ESKOV 1994).
In 1998-99 some linyphiid spiders, be-
longing to the mainly Siberian genus W. uralensis belongs to the rarest and
Wubanoides ESKOV 1986 (ESKOV & MARUSIK most mysterious European species of spiders.
1992), were found in a block field in the Biology, ecology and distributional history
Harz Mts. (Fig. 31), Lower Saxony, North- have remained unknown till now. In total
west Germany (SCHIKORA 2001). The spi- no more than 9 single records have been
ders were tentatively assigned to Wubanoides made (SCHIKORA 2001; BuCHAR & RÖZICKA
uralensis (PAKHORUKOV 1981), since they 2002, RÖZICKA pers. comm.). All of them re-
appeared taxonomically distinct, when fer to extensive low mountain range block
compared with paratypes of this species. fields, where the spider exclusively inhabits
Hitherto the only few Central European oc- the dark, deep subterranean cleft system.
currences of W. uralensis were known from Since 1999 special trap types have allowed
the Czech Republic (e.g. RÖZICKA et al. catches of living W. uralensis in the Harz
1989, RöziCKA 1990, RÖZICKA & ZACHARDA Mountains. Even egg sacs of the spider were
1994, RÖZICKA 1997, RÖZICKA &. HAJER found attached to these traps. In the follow-
1996, BUCHAR &. RÖZICKA 2002). The main ing period living specimens and egg sacs
distribution area of W. uralensis appears to were the basis for successful ex ovo-rearings
be the north-east Palaearctic (North Asia of W. uralensis. Improved rearing methods
sensu ESKOV 1994). Here, the species is now permit the culturing of several genera-
known from West Siberia (Polar Cisuralia, tions. The description of courtship behav-
northern and middle Urals, southern Urals, iour and postembryonic development of W.
Yenisei), South Siberia (West Sayan, East uralensis is thus one goal of this paper. The Denisia 12, zugleich Kataloge
Sayan, Tannu-Ola, Khamar-Daban and complete life cycle of a linyphiid spider, der OÖ. Landesmuseen
Neue Serie 14 (2004), 327-341
© Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at
from egg to adult, has obviously been stud- tened weekly with a few drops of water. Spi-
ied only rarely. As a further goal, based on derlings hatched from egg sacs were kept
all currently available material, a first separately in small glass vessels (25 ml; 1 cm
overview of the geographic variation of charcoal-plaster layer). Pieces of perforated
taxonomic characters is given. airtight film were used to cover vessels and
tubs. All mated females and juveniles be-
yond moulting were fed (almost) daily with
Materials and methods
arthropleonous (spring-summer) and sym-
Investigated materials phypleonous (autumn-winter) Collembola.
The size of the prey did not considerably ex-
Whenever juvenile spider instars are
ceed the spiders individual body length.
mentioned in the following, they were
Keeping and rearing were maintained in the
caught alive and reared to adulthood in cap-
dark under normal room conditions (Tem-
tivity.
perature 15-22°C).
Germany: Lower Saxony, Harz Mts., Acker-
Measurements: The growth of the juve-
Bruchberg mountain range, Altenau, quartzite
nile spiders was monitored on an (almost)
block field (740 m NN).
daily basis by recordings of body dimensions
Adults: 19 (live) 21.9.1998; 1C (live)
27.6.1999; 19 dive) 20.7.1999; 19 (live) 22.9. of live specimens, hanging upside down in
1999; 1 9 (live) 26.6.2002; 1 9 (live) 24.5.2003; their sheet webs (stereoscopic binocular mi-
2cr o-, 1 9 30.5.-27.6.1999; 1 9 27.6.-3.7.1999; croscope, magnification x40 to x80, cali-
lor, i9 27.6.-2O.7.1999; I9 20.7.-22.9.1999; brated ocular micrometer). The following
19 22.9.1999 - 17.4.2000; lo- 9.7.-6.8.2001; characters were measured: a) sternum width
1 or, 1 9 22.4.- 7.6.2002; 1 a 7-26.6.2OO2; 1 9 between coxae II, b) maximum breadth of
20.8.- 20.9.2002; 1 9 24.5.-13.6.2003. Juveniles
opisthosoma, c) total body length and d) leg
(1st to 4th free instar): I9 22.9.1999, 10-
span. The leg span was measured only in
24.9.2001; 3 0-o- 26.6.2002, 1 o- 20.8.2002,
undisturbed, relaxedly resting specimens.
2 O-a 20.9.2002. Adults from ex ovo-rearing
1999-2002: 19 o-a, 269 9 (CHBS; 1 o-, 19 Courtship, mating behaviour: All ob-
CKTh; 1 a, l 9 CVR). servations were made in September and Oc-
Czech Republic: A) Moravia, Krälicy tober at about 19 °C between 8:00-10:00
Sneznik Mt., southern slope, 1350-1400 m NN,
p.m., using a stereoscopic microscope (mag-
boulder debris, 19 26.7.1994; B) Moravia, Je-
nification xlO) at half-light conditions. Re-
seniky Mts., Ztracene Kameny Me, southern part
cently moulted females were allowed to in-
of the main crest, 1220 m NN, phyllite and
habit a 500 ml plastic tub (see above) for at
quartzite block accumulations, 10", 19
least 2 days, to establish their sheet web.
15.7.1993 - 27.7.1994; C) Bohemia, Krkonose
Mts., Snezka Mt., western slope, mica schist Then single males were introduced and con-
taluses, 1540-1550 m NN, Iff 2.7.1988 - stant observations started until successful
26.8.1989 (leg. V. RuzßKA; CHBS), 1 a 1.8.2003 mating had occurred.
(live, subadult; leg. HBS). D) North Bohemia,
Developmental stages: For both sexes a
Liberec, JeSted Mt., southwestern slope, about
980 m NN, quartzite block field (all specimens certain number of successive instars from ex
caught alive), 1 cr (subadult), 5 9 9 (4 adult, 1 ovo-rearings were fixed in 70 % ethanol.
as 3rd instar), 31.7.2003 (leg. V. RÖZÖCA & HBS; Specimens just before, or shortly after a
CHBS). moult were not considered. Lateral prosoma
USSR, Siberia (sub W. longicomis): 1 c, 1 9 views of all instars were drawn following dis-
(Paratypes; Krasnoyarsk Area, Yenisey River, section of the legs between coxae and femo-
Mirnoye, in stack of fire logging, 6.9.1979, leg. K. ra.
ESKOV;SMF32149).
Abbreviations: E = embolic division; ED
Methods
= entrance duct; Emerg = emergence from
Ex ovo-rearing: Reproductive females egg sac; Fe = femur; L/TL = length/total body
from the wild and breeding pairs were kept length; Lc,/!^ = main/secondary branch of
in slightly conical 500 ml plastic tubs con- lamella characteristica; Oj 9 = male/female;
taining a plaster-charcoal layer with a piece OpW = opisthosoma width; PME = posterior
of quartzite rock. The plaster layer was mois- median eyes; Prs = prosoma; R = radix;
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Rc,/Rc = receptacula; SteW = sternum characters in European populations (Czech
2
width; T = tegulum; T, = terminal apophysis Republic, Germany) are indicated by a local
of tegulum; Ta = tarsus; W = width; e.o. = ex cancellation of the column subdivision.
ovo; d = dorsal; pi = prolateral; rl = retrolat-
The designation of the male palpal scle-
eral; v = ventral; s.d. = standard deviation;
rites is according to ESKOV (1986). In all da-
SMF = Senckenberg Museum Frankfurt;
ta on body measures and tibial spinulation of
CHBS, CKTh, CVR = author's collection,
specimens from the Siberian main area, data
coll. K. THALER, coll. V. RÖZÖCA.
from ESKOV (1986) have also been included
Measures: Linear measures, if not other- (Symbol: *). Measurements of specimens
wise indicated, are in mm. from European populations are given as
mean and range (in brackets). Tibia spine
numbers refer to the normal case, assigned
Results
numbers in brackets inform about 1-2 cases
of observed exceptions.
Geographic variation and description
of a new subspecies Description of a new subspecies: Disre-
Geographic variation: The study of the garding some few minor differerences, the
geographic variation of taxonomic charac- comparison of taxonomic characters shows
ters in W. uralensis is exclusively based on that the Central European specimens of W.
specimens, which were caught in the wild. uralensis are clearly distinct, when compared
The respective descriptions of differing char- with the Siberian paratypes. Subject to fur-
acters are purposefully brief and provided in ther investigations, the observed differences
tabulated form for clarity. In the three- in somatic characters are here regarded as
columned table (see below) the spiders are the expression of geographic variation (see
distinguished according to their geographical Discussion). Hence, all currently known Eu-
origins. The sequence is from East (Siberia; ropean W. uralensis populations are assigned
** = geogr. position of the city of Krasno- to a separate, allopatric taxon on a subspe-
yarsk) to West (Germany). Corresponding cific level.
USSR, Siberia, Krasnoyarsk Area Czech Republic Germany
55°55'N, 93°00'E** 50°43'-50°45'N, 14°17'-15°49'E 51"47'N, 10°27'E
1 c, 1 9 (Paratypes) 4ccr, 79 9 14cc, 149 9
General Appearance
Comparatively dainty spiders: Comparatively big, robust spiders:
TL^* = 2.10-2.20 TL ,„ = 2.40 (2.04-2.85) / 2.36 (2.03-2.90)
* = 0.80-0.83 / 0.74-0.76 PrsW „„ = 0.94 (0.86-1.02) / 0.84 (0.78-0.89)
= 0.93-0.95 / 0.87-0.90 PrsL ,„ = 1.14 (1.05-1.30) /1.02 (0.94-1.10)
Legs/femora not noticeably long: Legs/femora noticeably long:
Leg I/IV L„ = 5.6/5.5 x PrsW Leg I/IV L„ = 6.9/6.8 x PrsW
Leg I/IV L, = 5.5/5.4 x PrsW Leg I/IV L, = 6.4/6.6 x PrsW
Fe I L„ = 1.44 x PrsW (1.50*) Fe I L„= 1.79 x PrsW (1.68-1.89)
Fe I L« = 1.46 x PrsW (1.53*) Fei L„= 1.70 x PrsW (1.63-1.81)
Tibia spines: males
d pi rl V d Pi rl V
Til 2 0 0 0 Til 2 (3, 4) 1(0) 1(0) 1-3
Till 2 0 1 0 Till 2 0-1(2) 1 1-2 (0, 3)
Tilll 2 0 0 0 Tilll 2 0(1) 0-1 0-2
TilV 2 0 0 0 TilV 2 0-1(3) 0-1(2) 0-2
Tibia spines:females
d P" rl V d Pi rl V
Til 2 1 1 0 Til 2 1(2) 1(2) 1-3 (4)
Till 2 0 1 0 Till 2 0-1 1 1-2
Ti III 2 0 0 0 Tilll 2 0 0-1 0-2
TilV 2 0 0 0 TilV 2 0-1 0-1 0-1(2)
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USSR, Siberia, Krasnoyarsk Area Czech Republic Germany
55°55'N, 93°00'E** 50°43'-50°45'N, 14°17'-15°49'E 51°47'N, 10°27'E
1 a, 1 9 (Paratypes) 4crcr, 79 9 14crcr, 149 9
Male Prosoma
Prosoma, when seen from above, well Prosoma, when seen from above, clearly longer than wide, rather pear-
convex, slightly longer than wide, with shaped, with widest part in proximal prosoma third (Fig. 12).
widest part in prosoma middle (Fig. 9).
Postocular horn short, conical, straight, Postocular horn long, distally curved (Fig. 22, 11) reaching the anterior
distally not curved (Fig. 10), not pro- margin of (Czech specimens) or clearly projecting the PME (German speci-
jecting the anterior margin of PME mens) (Fig. 12). The robust terminal seta either parallel to body axis or
when viewed from above (Fig. 9). The slightly pointing downwards (Fig. 22, 11). Fig. 11 shows head region of a
robust terminal seta directed forward single malformed male, having a double seta (ex ovo-rearing 2000, Harz
and upward at an angle of approxima- Mts.).
tely 30°.
Posterior prosoma comparatively Posterior prosoma noticeably prolonged and ending flattened. Head re-
short, ending blunt and rounded. gion distinctly set off against proximal prosoma half (Fig. 22).
Head region not especially
pronounced (Fig. 10).
Except head region, prosoma without Prosoma flanks with numerous short spines, often in rows (Fig. 22).
bristles or short spines.
Male palp
Lc main branch (Lc,) narrow and rib- Lc main branch similiar to specimens Lc main branch rather wedge-sha-
bon-like, distally gradually tapering. from Harz Mts., but upper terminal ped, distally rapidly tapering. Upper
Upper margin almost straight, both tooth small, lower terminal tooth margin distinctly curved, both late-
lateral terminal teeth short and une- fairly rough and cone-shaped (Fig. ral terminal teeth slim, comparative-
qual in size (Fig. 1). 15). ly long and almost equal in size (Fig.
5, 14).
Maximum 9 : L= 1 : 8.2 Maximum 9 : L= 1 : 5.5 Maximum 9 : L = 1 : 5.6-6.1
Proximal cymbium claw curved almost Proximal cymbium claw basally almost straight, only terminal half slightly
equally sickle-like (Fig. 2) curved (Fig. 6)
Basic embolic part a semi-circular pla- Basic embolic part a trapezoidal plate, the protruding embolic spur claw-
te, the protruding embolic spur slim like, proximal part widened (Fig. 6).
and long (Fig. 2).
Rounded terminal radix corners (R) Rounded terminal radix corners almost equal in size with basic, trapezoidal
smaller than basic, semi-circular embo- embolic part (Fig. 6)
lic part (Fig. 2).
Epigyne and Vulva
Epigyne subconical, roughly heart- Epigyne similar to specimens from Epigyne subconical, slightly remind-
shaped, centre part of anterior mar- Harz Mts., but centre part of anterior ing of a bike saddle, centre part of
gin with flat convex projection, late- margin with strong convex projec- anterior margin almost straight, late-
ral margins almost straight or very tion (Fig. 16). ral margins clearly concave (Fig. 7,
slighly concave (Fig. 3). 13).
Entrance ducts starting anteriorly from Entrance ducts starting anteriorly from copulatory opening oblique (Fig. 8).
copulatory opening almost right-an-
gled (Fig. 4).
Wubanoides uralensis lithodytes, same locality, 1 a, 1 9 22.4.-7.6.2OO2, 1 9
new subspecies 22.9.1999, 1 a 24.9.2001, leg. HBS, for the
time being retained in CHBS.
Types: Holotype c, Allotype 9. trap
catches, 27.6.- 20.7.1999, Northwest Ger- Etymology: Greek: "lith-" = rock, stone;
many, Lower Saxony, Harz Mts., Acker- "dyt-" = diver. The subspecific epithet al-
ludes to the exclusive habitat of all current-
Bruchberg mountain range south-west of Al-
ly known populations in Europe (see Intro-
tenau, open extensive quartzite block field
duction).
(51°47' N, 1O°27' E), leg. HBS, deposited in
the Museum of Natural History, Humboldt The subspecific status of specimens from
University, Berlin (ZMB 35218). Paratypes: European populations is founded on the allo-
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Fig. 1-8: Wubanoides
uralensis uralensis
(Siberian paratypes;
1-4) and W. u.
lithodytes nov. subsp.
(Harz Mts.; 5-8).
1: Left male palpus,
lateral view.
2: ditto, mesal view. 3:
Epigyne.
4: Vulva, cleared,
ventral view.
5: Left male palpus,
lateral view.
6: ditto, mesal view.
7: Epigyne.
8: Vulva, cleared,
ventral view. Scale
lines = 0.25 mm.
Rc
2
8
metric differences (leg lengths; see above), noticed 45-75 minutes after the male came
the presence of ventral tibia spines at least in contact with the female web.
on legs I—11 (see above), prosoma characters
Courtship: Once in contact with the
in males (Fig. 12, 22 versus 9-10), and on
web of a female, the male of W. uralensis is
characters of the male and female copulato-
mostly motionless for several minutes. Then
ry organs (Fig. 5-8, 13-16 versus 1-4).
it starts jiggling the abdomen impulsively
Courtship and mating behaviour and rhythmically, and enters the web in a
creeping way (Fig. 46). Soon the male dis-
Courting and mating behaviour was ob-
plays also additional impulsive and sudden
served in five Wubanoides couples (Harz
Mts.). Spiders from the wild (caught as ju- body movements. The web vibrates marked-
veniles) and/or specimens from ex ovo-rear- ly. Up to five jig impulses are followed by a
ings were brought together some days after short break, then the jiggling of the ab-
their final ecdysis. Usually copulation was domen starts anew. Stridulation begins, the
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Fig. 9-16: Wubanoides 10
uralensis uralensis
(Siberian paratype; 9, 10)
and W. u. lithodytes
(Germany, Harz Mts.:
11-14; Czech Republic:
15, 16).
9: Male prosoma,
dorsal ly,
10: ditto, laterally.
11: Head region of
malformed male with
double seta,
lateral view.
12: Prosoma,
dorsal view.
13: Epigyne.
14: Lamella
characteristica, left palp,
laterally.
15: Lamella
characteristica,
left palp, laterally
(Snezka Mt).
16: Epigyne (Krälicky
Sneznik Mt.).
Scale lines = 0.25 mm.
16
13-16
palps are moved up and down alternately. courtship display again. When there are no
The stridulatory bristle, mesally surmounted further acts of aggression on part of the fe-
on a small tubercle of the basal palpal femur male, the male usually approaches the fe-
end, is scraped along the stridulatory ridges male directly. Sometimes even foreleg con-
laterally of the cheliceral bases. The result- tacts can be observed. The male now starts
ing vibrations of the palpal bulbi are clearly to run around the female in curves, dabbing
visible. Unmated females react either pas- its opisthosoma tip regularly onto the web,
attaching its own silk threads.
sively, or rush towards the intruder. Very of-
fensive females try to repulse the male with The male excitation obviously increas-
their forelegs. In this case the male escapes es, sudden body movements and opisthoso-
from the web, but soon starts to perform the ma jiggling are carried out at increasingly
332
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Fig. 17-22:
Wubanoides uralensis
lithodytes (ex ovo-
rearing; Harz Mts.).
Postembryonic
development of
males, lateral
prosoma views, legs
dissected off.
17: First post-
embryonic instar (sex
unknown).
18: Second instar (=
first free instar; sex
unknown).
19: Third instar male.
20: Fourth instar male.
21: Fifth instar male
(subadult).
22: Sixth instar male
(adult). Scale line =
0.5 mm.
shorter intervals. Palpal stridulation activity starts to work on its palp tips alternately
now resembles a drumming. Phases of jig- with the chelicerae.
gling now last for 30-70 seconds and culmi-
Sperm web construction: The male
nate with a 9-15 second stridulation. Dur-
bites a hole into the female's web, having a
ing stridulatory activity, the male takes up a
diameter of about 1.5-2 body lengths. With
long-legged posture below the web surface,
nervous, convulsive movements it builts a
but at the cessation of the stridulation the
sperm web inside the opening within some
leg positions are re-arranged. Each phase of few seconds (Fig. 47). In the course of sperm
courting is followed by a break of up to 140 web construction the male climbs up sever-
seconds. The female is now frequently sur- al times to the sheet web surface and de-
rounded completely by the male, which posits a droplet of sperm from the epigastric
continues attaching its own threads to the genital opening onto its sperm web. The
web. On this occasion the male usually tiny sperm web is irregularly triangular (e.g.
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Fig. 23-30:
24, 26, 28, 30
Wubanoides uralensis
lithodytes (ex ovo-
rearing; Harz Mts.).
Postembryonic
development of
females, lateral
prosoma views, legs
dissected off.
23: Third instar.
24: Ditto, epigynal
region.
25: Fourth instar.
26: Ditto, epigynal
region.
27: Fifth instar
(subadult).
28: Ditto, epigynal
region.
29: Sixth instar (adult).
30: Ditto, epigyne.
Scale line = 0.5 mm.
30
23, 25, 27, 29
1.6 x 1.3 x 0.8 mm), and is tensed up with metatarsi of the forelegs. After some initial
three silk threads. Sperm reception takes repulsive movements, the female raises both
place while the male sits below the web sur- frontal leg pairs and remains in this posi-
face. Both palp tips are brought up alter- tion. The soft, flexible basal part of the epi-
nately to the sperm web from above in a gyne becomes expanded and resembles a
rather rapid sequence (Fig. 48). A male is whitish proboscis (Fig. 49). Standing head
capable of constructing a second sperm web to head, the male now pushes impetuously
in the course of courtship. forward with its prosoma underneath the fe-
male's prosoma. On this occasion the female
Mating: A short time after sperm recep-
tion the male starts courting again. The fe- fixes the male postocular protuberance be-
male is now pressurized severely by the male tween her chelicerae (Fig. 50). Doing this,
from the front and laterally, using tarsi and the robust male terminal seta obviously
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Fig. 53:
Wubanoides
uralensis lithodytes
- Course of the
individual
development in a
female from the
egg (29 August) to
the adult (24
November 1999).
Ex ovo-rearing.
SteW = sternum
width; OpW =
opisthosoma width;
TL = total body
length; Emerg =
emergence from
egg sac.
functions as a guiding device. Almost con- sisted of a total of 25 egg sacs from eight
temporaneously the alternating insertion of mated females and, additionally, 2 egg sacs
the male's palps happens and the expansion from the wild. The spiders were able to es-
of the haematodochae become visible (Fig. tablish up to seven egg sacs (mean = 3.1;
51). The observed copulations were rather range = 1 to 7). They were built mainly in
short and lasted only 20-120 seconds. The small rock depressions, or on the plaster
female partner initiates the separation and ground of the plastic tubs. Establishment of
leaves the male. No multiple matings could the first egg sac after mating or after the pro-
be observed in females, but males can suc- duction of a prior egg sac, took 9.9 days on
cessfully inseminate more than one female. average (s.d. = 40; range = 3 to 30). The
Obviously the period after final ecdysis, in egg sacs are silky white. The total length of
which females are willing to mate (one or one measured egg sac including of its loose
two weeks), ends with the start of the egg peripheral silk layer was 6.8 mm. The rather
maturation process. dense padded central part, containing the
egg bale was about 1.7 mm in diameter.
Postembryonic development
The egg numbers ranged from seven to
All body measures of the free instars ex-
14 (mean = 10.2, s.d. = 2.0). Both egg sacs,
clusively refer to specimens shortly after a
which were found in the wild (11.6.2001,
successful moult, before starting/continuing
20.8.2002), contained nine eggs each. The
to trap prey again. A distinction of the body
mean egg diameter was 0.54 mm (n = 24;
measures between both sexes is neglected in
s.d. = 0.03, range = 0.50 to 0.60). The eggs
the following, since no clear or distinct dif-
are spherical, pale yellowish in colour, and
ferences were found shortly after a moult.
stick together in a bale with the shape of a
The free instars of development need mulberry. The diameter of two measured egg
four moults to reach adulthood. Both sexes bales was about 1.3 mm.
can be distinguished for the first time in the
First postembryonic instar (Fig. 17,
second free instar by the shape of their palp
34): 10-12 days after oviposition and 2-3
tips (Fig. 19 versus 23). According to 169 ex
days before hatching, the egg becomes elon-
ovo-specimens from 20 egg sacs, the sex ra-
gated, the prosoma and appendages of the
tio in W. uralensis lithodytes appears slightly
embryo become visible through the silk lay-
skewed in favour of the male sex (1 : 0.8;
er of the egg sac. 13.5 days, on average, after
males = 94, females 75). Details on the du-
egg sac establishment the eggs hatch (n = 5
ration of the entire postembryonic develop-
egg sacs; range = 12-15 days). It was not ob-
ment are given in connection with the adult
served if the covers of the egg (chorion and
stage (5* free instar).
vitelline membrane) were broken and shed
Egg sac and egg (Fig. 33): The data ba- together with the embryonic cuticle, as it
sis for measurements and observations con- has been reported by other investigators (e.g.
335
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GALIANO 1991, GALIANO &. GOLOBOFF Third instar (2nd free instar; Fig. 19,
1996). The shedding of the embryonic cuti- 23, 36): In the second free instar the dis-
cle would be the first true moult. On the as- tinction of both sexes becomes possible for
sumption, that such a moult also exists in the first time. The distal palpus section of
Wubanoides, the incomplete instar, which early males is, in contrast to early females,
left the egg and remained in the egg sac, is widest in the middle (Fig. 19 versus 23).
here regarded as the first postembryonic in- The prosoma of early males shows a small
star. postocular tubercle, surmounted by a slight-
ly curved bristle. In early females this tuber-
The hatchlings of the first postembryon-
cle is only indicated. The initial stage of the
ic instar (total length: 0.77-0.80, n = 3) are
epigynal development is characterized by a
covered by a hairless cuticle, except for the
slight protuberance of the upper margin of
distal part of the palps, where some short
the epigastric furrow (Fig. 24).
bristles exist. The pale yellowish hatchlings
are eyeless and show a characteristic dorsal Colour: c/ 9 : Sternum anthracite grey,
elevation. Tarsi and metatarsi of all limbs blackish granulated. Opisthosoma ventrally
are still joined, cheliceral claws are not visi- pale reddish brown, dorsally somewhat dark-
ble. Eyes and hairs of the developing second er. Prosoma (dorsally), legs, palps and basic
instar show through the cuticle only shortly part of chelicerae light whitish grey, later
before the second moult. In most cases the becoming yellowish.
second moult occurred three days after leav-
Total length (n = 164):
ing the egg.
mean 1.17 (s.d. = 0.06; range = 1.03-1.34)
Second instar (1st free instar; Fig. 18, Opisthosoma width (n = 161):
35): The second postembryonic instar is the mean 0.54 (s.d. = 0.05; range = 0.42-0.69)
first free instar. The first free instar spider- Sternum width (n = 162):
lings (n = 180) left the egg sac at the earli- mean 0.35 (s.d. = 0.01; range = 0.33-0.44)
est eight days after egg sac establishment Leg span (Ta I-Ta IV; n = 57):
(mean = 18.3 days, s.d. = 4.1, range = 8 to mean 3.66 (s.d. = 0.27; range = 3.15-4.25)
23) and 2-3 days after the second moult. Fourth instar (3rd free instar; Fig. 20,
They show a characteristic dorsal elevation
25, 37): Young males now show a distinctly
with a long bristle. A distinction of both swollen terminal palpal section, with the
sexes was not yet possible at this stage. Af- widest part in the proximal third. The post-
ter leaving the egg sac, the spiderlings dis- ocular tubercle is now characteristic and
perse and establish their first small sheet more prominent, its curved bristle is
webs. It was found to be important that they stronger. Fourth instar females exhibit a
have an opportunity to catch prey within shallow postocular elevation. Their termi-
three or four days at the latest. Otherwise nal palpus section is distally tapering gradu-
the spiderlings frail and become too weak ally. In the epigynal region a rounded pro-
for a successful hunt. jection indicates further epigynal develop-
ment (Fig. 26).
Colour: Sternum greyish yellow.
Opisthosoma ventrally greyish amber- Colour: cy/9: Sternum grey, blackish
coloured, dorsally and laterally somewhat granulated. Opisthosoma ventrally dark red-
paler. Legs and palps whitish yellow, di- dish brown to pale brown, dorsally and lat-
aphanous. Prosoma dorsally light yellowish erally pale whitish or yellowish brown. Pro-
white and diaphanous pale greyish. soma dorsally yellowish brown to dull amber
coloured, as are chelicerae, palps and legs.
Total length (n = 161):
Spinnerets ventrally blackish.
mean 0.86 (s.d. = 0.04; range = 0.77-0.96)
Opisthosoma width (n = 149): Total length (n = 138):
mean 0.35 (s.d. = 0.04; range = 0.29-0.48) mean 1.56 (s.d. = 0.09; range = 1.35-1.93)
Sternum width (n = 151): Opisthosoma width (n = 137):
mean 0.29 (s.d. = 0.01; range = 0.27-0.33) mean 0.72 (s.d. = 0.07; range = 0.60-1.03)
Leg span (Ta I-Ta IV; n = 10): Sternum width (n = 136):
mean 2.15 (s.d. = 0.12; range = 1.88-2.30) mean 0.43 (s.d. = 0.02; range = 0.38-0.48)
336