Y. D. Lubin, B.D. Opell, W. G. Eberhard, and H. W. Levi.
Orb Plus Cone-webs in Uloboridae (Araneae), with a Description of a New Genus and Four New Species.
Psyche 89:29-64, 1982.

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ORB PLUS CONE-WEBS IN ULOBORIDAE (ARANEAE), WITH A DESCRIPTION OF A NEW GENUS
AND FOUR NEW SPECIES
BY Y. D. LUBIN,' B. D. OPELL,*, W. G. EBERHARD,~ AND H. W. LEVI~
Spiders of the genus Uloborus (Uloboridae) characteristically spin horizontal orb-webs with a sticky spiral of cribellar silk. We describe here the webs of U. conus, U. albolineatus, U. bispiralis, U. #2072, U. trilineatus, and Conifaberparvus which are modifications of this basic uloborid orb-web form and include cones composed of regular arrays of threads beneath the orbs' lower faces. The web building and prey capture behaviors of U. conus (observations of YDL) are also described, and descriptions of Conifaber parvus new genus, new species and the new species U. conus, U. albolineatus, and U. bispiralis are provided (by BDO). Uloborus conus was found at three localities in Papua New Guinea: 1) in lowland wet forest, Gogol Forest Reserve near Madang, Madang Province, 2) in a Pandanus swamp (freshwater) and a mangrove swamp (brackish) at Buso, Morobe Province, and 3) in the understory of klinki pine (Araucaria hunsteinii) plantations at 1200 m elevation in McAdam Memorial Park near Wau, Morobe Province. Webs were built about 0.5 to 2.0 m above the ground in gaps formed by the uppermost, generally vertical branches of small shrubs and saplings. They were always found in humid, shaded 1. Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Panama and Department of Zoology, University of Florida, Gainesville, Florida, 32611. 2. Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061.
3. Smithsonian Tropical Research Institute and Escuela de Biologia, Universidad de Costa Rica, Ciudad Universitaria "Rodrigo Facio", Costa Rica. 4. Museum of Comparative Zoology, Harvard University, Cambridge, Massachu- setts 02138.
*Manuscript received by the editor September 25, 1981.



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30 Psyche [vo~. 89
locations. Several individuals were kept and observed in an insect- ary at the Wau Ecology Institute (WEI).
Uloborus albolineatus and U. bispiralis were found on the Gazelle Peninsula, East New Britain (ENB), Papua New Guinea. The webs of U. bispiralis were observed on the Lowlands Agricultural Experi- mental Station (LAES) at Kerevat, ca. 100m elevation, in cocoa plantations and in secondary growth lowland forest and near Malasat (END) at ca. 600m elevation. One web of U. albolineatus was observed at LAES in secondary-growth forest along a river. A single mature female of Uloborus #2072 (numbers refer to specimen numbers placed in vials) was found (by WGE) near Dan- deli, Karnataka, India, in the foliage of a bush growing in a teak forest. Uloborus trilineatus is common in undergrowth of gallery forest in eastern Colombia where WGE worked extensively. The webs described here were found at Finca Chenevo, about 20 km SW of El Porvenir, Meta, and Finca Mozambique, about 15 km SW of Puerto Lopez, Meta. Conifaber parvus was also found at Finca Mozambique (by WGE) where it occurred in periodically flooded forest but not in surrounding savanna.
Webs were first dusted with cornstarch or talcum powder using either the method described by Eberhard (1977a) or Carico's (1977) modification of this method, and then measured and photographed. All specimens mentioned in this paper are deposited in the Museum of Comparative Zoology.
Uloborus conus*
The Web
The web of U. conus has three parts: the inner orb, the rim, and the cone (Fig. 1). The inner orb and rim are in nearly the same plane and are more or less horizontal. The inner orb consists of a closed hub, radii and a few loops of non-sticky spiral, while the rim has several loops of sticky, cribellar spiral which end where the rim radii join those of the inner orb. Rim radii are continuous with those of the cone, and those of the inner orb are attached to them. Cone radii are attached in groups of two or three to a central guy thread which *This is a new species decribed below.




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19821 Lubin, Opell, Eberhard, Levi - Uloboridae 3 1 Figures 1-2. Web of Uloborus conus. 1. Side view showing the rim sticky spiral (RS), inner orb (I), cone (C) with jagged sticky spiral (CS) on a framework of radii and non-sticky spiral, and cone radii (CR) converging toward a central guy thread. Note that 2-3 cone radii are attached together to form one thread which attaches to the cone guy thread, and that these attachments are dispersed along the guy thread so that there is no single apical point to which all cone radii attach. 2. Top view showing typical Uloborus-type hub and non-sticky spiral of the inner orb. The cone with its jagged sticky spiral (CS) is seen through the plane of the orb. Note the gap between the non-sticky spirals of the cone and inner orb on the one hand and the rim sticky spiral on the other. The cone sticky spiral can be seen as a continuation of the rim spiral (arrow points to beginning of cone sticky spiral).



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3 2 Psyche [vo~. 89
is in turn attached distally to a leaf or branch. The cone has a non- sticky spiral and a few irregularly-spaced, jagged turns of cribellar silk. This jagged sticky spiral is a continuation of the innermost sticky spiral loop in the rim (Figs. 2, 4). The hub of the inner orb (Fig. 2) is similar to that of other uloborid orbs, e.g. U. diversus (Eberhard, 1972), and its spiral continues outward to form the non-sticky spiral of the inner orb. There is always a large gap between the last turn of this spiral and the innermost loop of sticky rim spiral (Figs. 1, 2). Sticky spiral loops in the rim are more tightly spaced than are either the non-sticky spiral loops of the inner orb and cone or the cone's sticky spiral. The outermost loop of rim spiral often follows a zigzagging path, with some segments of the sticky silk found on the radii (Figs. 2, 3). This zigzagging was more pronounced in some webs than in others and was generally most evident on the side of the orb which was larger (the orbs were rarely perfectly symmetrical). Variations on this basic pattern were seen. Webs of immatures frequently had only a narrow rim, sometimes with only a single loop of sticky spiral. Some webs had a few loops of sticky spiral on the inner orb, with the non-sticky spiral left intact (Fig. 4). Webs of two adult females and several immatures had thin linear stabilimenta at their inner hubs. Adult males were found sitting on webs similar to those of immatures, but it was not determined if these were of their own construction. Adult males did not build webs in captivity. Web Building Behavior
Web building by two adult females was observed from start to finish and various stages of web construction were seen on four other occasions. Durations of different stages of construction were noted for one of the adult females. Web construction began late at night or in early pre-dawn hours. The inner orb and cone of the old web were probably removed early in the night, but this behavior was not observed. One WE1 female was found sitting at the center of a rudimentary web consisting of a partly collapsed rim and a few radii, and had a ball of silk in her mouthparts which shrank visibly as it was,(presumably) ingested. This spider removed the rest of the rim and added the material to the ball of silk in her chelicerae before building the new web. Reusing frame threads from the previous web, the spider began construction by laying new radii.



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Figures 3-4. Web of Uhbwus conus. 3, Detail of first (outermost) loop of rim sticky spiral showing zigzag path with sticky silk laid directly on the radii. 4. Top
tiew of web with I % loops of sticky spiral (IS) in the inner orb(1S). Also visible is the cone sticky spiral (CS) continuing in from the rim spiral (RS) and the zigzag outer loop of rim sticky spiral.




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34 Psyche [Val. 89
Radii and non-sticky spiral were laid as in U. diversus (Eberhard, 1972) and their construction lasted 5 and 1.5 minutes, respectively. Radii were laid by walking out from the hub on an existing radius with a dragline, attaching the dragline to a frame thread, and then doubling it by walking back to the hub with another dragline. At the hub the dragline was attached to a succession of adjacent radii (forming the closed hub spiral) before the next radius was laid. When most of the radii were completed, the spider continued the hub spiral outward to form the non-sticky spiral, laying occasional "tertiary radii" (Le Guelte, 1966) during the process. This non-sticky spiral did not reach the frame threads.
At the start of the sticky spiral even very faint light falling on the spider caused her to cease spinning and bounce up and down on the web. Consequently, observations of sticky spiral construction were made only sporadically, using indirect lighting. The first (outer- most) loop of non-sticky spiral was completed in 13 min. During sticky spiral construction the spider reversed directions five times in the larger part of the web. The sticky spiral was attached to each radius that it crossed, and the spider broke non-sticky spiral loops as she laid the sticky spiral. One immature female was observed laying a zigzag outer loop of sticky spiral. The sequence of attachments of the cribellar silk to produce the zigzag loop (Fig. 5a) was distinct from that involved in laying the normal sticky spiral loops (Fig. 5b). After meticulous, slow sticky spiral construction, which in one case lasted 3 hrs. 6 min., the spider suddenly began spinning out cribellar silk in a rapid and seemingly reckless fashion while moving inward toward the hub at an angle of about 25O to the last turn of the regular sticky spiral (Figs. 2, 4). After completing half a loop, the spider reversed direction and continued spiralling toward the hub, laying a jagged and irregularly spaced sticky spiral. The jagged spiral was attached to only a few radii, crossing 3-7 radii and, in some cases, several non-sticky spiral loops between attachments. The non-sticky spiral was left intact. This entire phase was very rapid and in one case the four jagged loops were completed in just 6 min. This jagged spiral was to become the sticky spiral of the future cone.
After completing the cone sticky spiral, the spider moved to the hub and slowly turned in a circle, pulling on successive radii with the first legs. After 2 min. she went out to the end of a radius and



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19821
Lubin, Opell, Eberhard, Levi - Uloboridae Figure 5. Construction of U. conus web.
(a) Sequence of attachments of sticky
silk to produce the outer zigzag loop of rim sticky spiral. The spider started at the junction of the radius (Rl) and frame thread (F), attaching the cribellar thread at point A, walked along Rl toward the hub and attached the cribellar thread at point B, about half way between the frame thread and outer loop of non-sticky spiral (NS). The spider then continued inward along Rl, combing out cribellar silk, reached the non-sticky spiral and ran rapidly across it and 213 of the way out on R2 without combing out additional silk. It then continued to walk out on R2, combing out cribellar silk and attached the thread at point C, the junction between R2 and the frame thread. The sequence was then repeated, walking in along R2, attaching cribellar thread at point D, etc. (b) Sequence of attachments of cribellar silk to produce the normal sticky spiral. The spider attached cribellar thread at point A on radius Rl, walked in on Rl, combing out cribellar silk, until it reached the temporary, non-sticky spiral loop (NS), then ran along the non-sticky spiral and out on radius R2 without combing out cribellar silk and attached the cribellar thread to R2 at point B.
dropped from it to a leaf below, attached her dragline to the leaf, and went back up the dragline and across the web to its hub on a radius, attaching the new dragline from the leaf to the hub. This formed the central guy thread of the cone. The spider then went down the guy thread, broke it, reattached it to a different point on the leaf, and then returned to the hub. By this time the hub was al- ready drawn down under tension, and the web formed a shallow cone. The cone was then elongated by cutting radii at their attachment to the hub, lowering their tension and then attaching them to the central guy thread by the sequence of behaviors shown in Fig. 6a, b.




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[Vol. 89
Figure 6. Construction of U. conus web.
Sequence of thread attachments in
forming the cone (web viewed from the side). Arrows indicate direction of movement of the spider. Dots are points where attachments were made or broken. (a) The spider went to point X on radius Rl at the edge of the hub, cut the radius, attached its dragline to the inner broken end and then let out additional dragline as it faced away from the hub. This was then attached to the outer broken end which had now moved to point XI. Usually adjacent radii were also broken and attached to radius RI at point Xi (see also Fig. 1). (b) The spider then walked back toward the hub to point Y, attached a dragline, ran to the hub and down the central guy thread (G), attaching the dragline at point Z. Radius Rl was thus pulled down toward the apex of the cone to form the cone radius YZ while the thread HY formed a temporary inner orb radius,
(c) To move the temporary inner orb radius up on the cone, the spider walked out on temporary radius HY and broke it at its attachment to the cone at point Y. The spider then attached a dragline to the broken end and walked out on radius Rl, reattaching it at point A at the inner edge of the rim sticky spiral. (d) The completed cone radius is indicated by line AZ and the new inner orb radius by line HA. The section AY of the cone radius bears the cone sticky spiral. The upper portion of the guy thread (HZ) was absent in the completed web, but it is not known when it was removed.
After forming the cone, the spider cut most of the temporary inner orb radii, thus collapsing the hub and leaving only a bit of silk to which a few temporary radii were attached. The spider then began replacing these temporary inner orb radii and at the same time completing cone formation by incorporating into the cone the



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19821 Lubin, Opell, Eberhard, Levi - Uloboridae 37 section of the original orb containing the jagged sticky spiral (Fig. 6c, d). This stage followed initial cone formation without interrup- tion, and it was difficult to determine when cone building ended and replacement and construction of new inner orb radii began. The spider went out to the cone along a temporary radius, broke the attachment to the cone and attached her dragline to the inner end of the temporary radius, then carried the radius upward by walking along radii and non-sticky spiral loops on the inner surface of the cone, and finally reattached it at or just inside (below) the innermost loop of the rim sticky spiral. She then walked back to the hub on the new radius, thereby doubling the thread. Upon reaching the center, she made attachments to form a new hub. The upper portion of the guy line was absent in finished webs, but it was not determined how it was removed.
Additional new inner orb radii were constructed in much the same manner as "normal" orb radii. The spider went out on an existing radius (or temporary radius) with a dragline, reached the cone non-sticky spiral, walked across it to the next cone radius, attached the dragline to the cone radius just below (inside) the rim spiral, and return to the hub on the new radius (doubling it). Consecutive radii were always laid with angles of more than 90å between them, perhaps serving to reduce differences in tension on all sides of the orb (Eberhard, 1981).
The last stages of web building, beginning with attachment of the dragline and ending with completion of the inner web, lasted 23 min.
Resting Postures
The spider normally sat under the hub with legs I and I1 slightly flexed and holding separate radii. When disturbed, the spider adopted a cryptic posture with legs I and I1 held together and flexed and legs I11 and IV pressed close to the body (Figs. 2, 4). This posture was adopted either at the hub or under a short "dragline" thread beneath the hub, which was attached to the hub at one end and to a radius at the other. When disturbed repeatedly, or when sunlight struck the web and made it visible, the spider dropped from the hub onto the dragline thread and bounced up and down on it. Spiders also bounced while wrapping prey and sometimes while going out to attack an insect or upon returning to the hub. This



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38 Psyche [vo~. 89
bouncing may be an anti-predator behavior similar to the bouncing flight of craneflies and the rapid vibrating of opilionids and pholcids.
Prey Capture Behavior.
Successful captures of five fruitflies (Drosophila-size), one 4 mm long dolichopodid fly, one unidentified 1 mm fly, three 3 4 mm ants, and one 5 mm lepidopteran larva were observed (by Y DL). Of these, seven were trapped in the rim and three in the cone. All but one sequence conformed to the description given below. Like other uloborids (Marples, 1962; Eberhard, 1969; Lubin et al., 1978) U. conus and U. bispiralis immobilize all insects by wrapping in silk. Spiders ran out to the cone on an inner orb radius to reach insects trapped in the rim sticky spiral, squeezed through the cone (often turning sideways to do so) and continued out onto the undersurface of the rim. If an insect was trapped on the cone sticky spiral, the spider went through the cone and ran down the outer surface of the cone. Upon reaching the insect, the spider often tapped it with legs I, turned 180å so that it faced the hub (or upward on the cone) and began to wrap. Initially the prey was wrapped from a distance by throwing sheets of silk backwards with legs IV. Later the spider moved into contact with the prey and held it with legs I1 and I11 while wrapping. The spider interrupted wrapping to cut sticky spiral attachments, then cut the inner radius attachment (toward the hub) and continued to wrap while holding the end of the radius with one leg I. Finally, the outer (distal) end of the radius was cut and the prey was held free of the web in legs I1 and I11 while the spider hung from the broken radius by legs I, bridging the gap with its body, and wrapped the prey with legs IV while rotating it occasionally with the palps or legs.
All prey were carried to the hub in the palps (with the aid of the chelicerae), held "overhead" in characteristic uloborid fashion. After transferring the prey package from the legs to the palps, the spider attached a dragline to the distal end of the broken radius and then to the proximal end, thus closing the gap. At the hub the spider again transferred the prey from the palps to legs I1 and 111 and wrapped it while hanging from the dragline thread beneath the hub. In most instances the dragline thread appeared to be broken and the spider spanned the gap with its body.




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19821
Lubin, Opell, Eberhard, Levi - Uloboridae Prey Capture Sequences With Different Prey Types. The only case not conforming to this description was that of a fruitfly caught on the inner orb; the spider wrapped it, secured it by reattaching it to the radius and fed on the prey in situ. U. conus rejected or ignored a number of insects offered as prey. Five small orthopteran nymphs 3-4 mm long (probably newly emerged) where given to adult females and all were rejected. On two occasions, the spiders approached and tapped the insects with legs I and then returned to the hub. In other instances the spider pulled the radii in the direction of the orthopteran, shook the web and then ignored it. The same individuals readily attacked fruitflies offered as prey after the orthopterans. Fruitflies were not attacked on three occasions when they were offered while the spider was already wrapping a prey or feeding at the hub. Two ants (Anopolepis longipes, 4mm long) were rejected under the same circumstances. Sequences With Multiple Prey.
On six occasions spiders feeding at the hub attacked second, or third prey thrown into their webs. These included two ants, two fruitflies, a dolichopodid fly and an unidentified small fly. On all but one occasion the spider carried the first prey in its palps as it ran out to attack the second.
In one instance a spider that had been
wrapping the first prey at the hub attached this insect to a dragline thread below the hub before going out to attack the second insect. The second prey was immobilized in the same manner as the first, but rather than cut this insect out and carry it to the hub, the spider secured the second prey at the capture site and returned to the hub to resume feeding on the first prey. While performing immobili- zation wrapping, the spider usually broke the radius attached to the prey on the inner side (toward the hub), but not on the outer side. Before leaving it at the capture site, the spider reattached the prey to the broken end of the radius, thus securing it at both ends. Eggsac and Eggsac Web.
The eggsac of U. conus is about 8mm long by 3mm wide, with angular projections along the edges (Fig. 7). It is suspended in an eggsac web on a strengthened radius of a former web, where the hub of the inner orb had been. The web is similar to those of U. diversus (Eberhard, 1969) and Miagrarnrnopes sp. near unipus (Lubin et al. 1978) and consists of frame threads, a few radii and one or more



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40 Psyche [Vol. 89
zigzag loops of sticky silk, with some sticky silk laid directly on the radii. The radii are attached to the main eggsac radius or to the eggsac itself. One female had a three-dimensional eggsac web consisting of a rudimentary cone and inner orb radii (Fig. 7) with sticky silk in both the plane of the orb and the cone. Unlike the eggsac webs of Miagrammopes, these webs were retained both day and night. Insects that became entangled in the sticky threads were attacked in the usual manner.
Females guarded their eggsacs (one per female) until the young emerged (13 days for one eggsac). Newly emerged spiderlings remained on the eggsac web for one or two days, then moved away and constructed typical Uloborus-type "baby webs", consisting of radial threads connected by a thin sheet of very fine, non-sticky silk (Szlep, 196 1 ; Eberhard, 1977b) without any cone. One immature, however, had an orb plus cone-web with a filmy "baby web" sheet where the rim sticky spiral would normally be found and also some "baby web" sheet on the cone. Structural spirals were present in the rim and inner orb; there was no sticky spiral. Uloborus bispiralis*
The cone web of U. bispiralis (Fig. 8) is similar to that of U. conus in that the cone sticky spiral is continuous with that of the rim, and the outer loop(s) of rim spiral follow a zigzag path, with some sticky silk laid on the radii. Unlike webs of U. conus, the inner orb non- sticky spiral extends right up to the innermost (last) loop of rim sticky spiral and all webs had a few loops of sticky spiral in the inner orb. Most webs also had a thin, linear stabilimentum of white silk across the inner orb, with a spider-size gap at the hub. Webs of juvenile females were similar in all respects to those of adults. None of the webs observed showed signs of repairs. Like those of U. conus, they are probably renewed daily. On one occasion only, a juvenile female was seen hanging inside the cone while an adult male fed on prey at the hub. Another adult male was observed sitting at the edge of an adult female's web and a third male was found sitting in a small cone-web (no sticky spiral was observed).
*This is a new species, described below.



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Lubin, Opell, Eberhwd, Levi - Uloboridae Figures 7-9.
Ulobonis. 7. Eggsac and three-dimensional eggsac web of U/o- borw emus. The female spider can be seen sitting in a cryptic posture to the left of the eggsac. Sticky threads (heavy white lines) occur in the plane of the former orb and on the rudimentary cone. 8. Web of Wloborus bispiralis. 9, Tubular eggsac of
Uloboms bispiralis with female sitting in cryptic posture at one end of the eggsac (arrow).




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42 Psyche [vo~. 89
The long, tubular eggsacs of U. bispiralis (34-40 mm long and 1.5 mm wide) have no angular projections (Fig. 9) and resemble those of Miagrammopes (Lubin et al. 1978). They are suspended along the radius of a former web of which only a few radii and frame threads remained intact. There was no evidence of sticky silk in the four eggsac webs examined. Spiders sat in line with the eggsacs, with legs I and I1 extended forward and legs IV grasping the eggsac, and were reluctant to move even when prodded.
Ulo borus albolineatus*
One individual of U. albolineatus was observed on a cone web similar to that of U. bispiralis. The rim spiral had one or two zigzag outer loops, and both the cone and inner orb had jagged loops of sticky spiral. The inner orb non-sticky spiral extended almost to the rim spiral. The female sat at the hub with legs I and I1 extended forward and held together and legs IV extended backward. Uloborus sp. (2072)
Only a single web was seen. It consisted of a somewhat inclined orb (43' with horizontal) with a cone underneath it which contained loops of sticky spiral (Fig. lOa, b). This web differed from those of U. Conus in having sticky spiral threads near the center of the horizontal orb (Fig. lOc) as well as near its edge, as well as having