1997. The Journal of Arachnology 25:11-19

NOTES ON THE REPRODUCTIVE BIOLOGY AND SOCIAL BEHAVIOR OF TWO SYMPATRIC OF (ARANEAE, )

Deborah R. Smith: Department of Entomology, Haworth Hall, University of Kansas, Lawrence Kansas 66045 USA

ABSTRACT. Populations of the facultatively communal species (Chamberlin 1924) and Philoponella arizonica (Gertsch 1936) (Uloboridae) occur sympatrically in the Chiricahua mountains of southeastern Arizona. This study compares reproductive biology, structure of communal groups, and feeding rates of the two species, and documents differences in their phenology, webs, web construction sites, egg-cases and spiderlings. I suggest environmental factors that may select for different reproductive strategies in the two species.

Many members of the family Ulo- lived than females and disappear from the boridae have been observed living in groups population during the course of the summer. (Opell 1979; Muma & Gertsch 1964). For Females can lay eggs throughout the summer only a few of these species has the nature of and may survive until early autumn, but in the their group-living behavior been investigated: populations studied no adult females overwin- the facultatively communal Philoponella ow- tered for a second breeding season. eni (see Smith 1982, 1983) and P. semiplu- Immatures hatch and emerge from the egg- mosa (Simon 1893)(see Lahmann & Eberhard case during the summer. As is true of other 1979); P. republicana (Simon 1891), with its uloborid , the young can spin webs in instar large, semi-permanent colonies (Smith 1985; the first post-emergence (Szlep 1961; Eberhard The Binford & Rypstra 1992); and a west African 1977). newly emerged spider? lack a functional and the orb Philoponella Mello-Leitao which was ob? lings cribellum; webs are served in a very large colony (Breitwisch they produce distinctive, containing hundreds of radial threads without a 1989). many Later instars a functional This study compares reproductive biology, sticky spiral. possess cribellum and webs that are similar feeding rates and group-living behavior of two produce or identical to those of adults in form (Szlep sympatric populations of group-living Philo? 1961; Eberhard 1977). ponella, P. oweni (Chamberlin) and P. arizon- The young remain with the female for a ica (Gertsch) (Uloboridae). Notes on the nat? variable length of time and attach their orbs ural history of the two species are also to her web; during the course of the summer presented, including structure of the egg- some or all of them disperse out of the ma? cases, the structure of the webs and substrates ternal web and build independent webs (Smith used for web-building in the two species. 1982). Young spiders over-winter as sub- of Philoponella oweni and P. Populations adults or younger immatures, and emerge the arizonica are in the south- broadly sympatric following spring to form the next generation western United States and northeastern Mex? of reproductives. ico & Gertsch The (Muma 1964; Opell 1979). Both species are facultatively communal; basic life of the two are similar cycles species that is, adult females of both species can be in southeastern Arizona. Field observations found living in small communal groups or as indicate that both are annual; sub-adults solitary individuals (Smith 1982, 1983). In the emerge from overwintering sites in the spring communal groups each female constructs her (early April to early June, depending on ele- own orb web and defends it against other vation). Mating takes place in late spring and adult females. The orbs are joined by their early summer. In general, males are shorter- support lines and space webbing. 11 12 THE JOURNAL OF ARACHNOLOGY

Reproductive biology: When a female pro? duced an egg-case it was given a color mark corresponding to that of the mother. To deter? mine mean clutch size (number of eggs per egg-case) for each species I collected the egg- cases after the young had emerged and examined their contents with a dissecting mi- croscope. As is true of most spiders, the young of Philoponella do not emerge from the egg-case immediately upon hatching from the egg; they remain in the egg-case for one in- Figure 1.?Egg-cases of Philoponella oweni star, molt, and emerge as second instar spi? (above) and Philoponella arizonica (below). derlings leaving behind both empty egg-shells and cast-off exoskeletons. In healthy I used the number of shells as Both species suffer from egg- by egg-cases egg a measure of the number of laid in the the chalcidoid Arachnopteromalus dasys eggs A Gordh (Pteromalidae) (Gordh 1976), which egg-case (Smith 1982). parasitized egg-case can be the absence of exoskel? greatly affects reproductive success of indi? recognized by etons from first instar and vidual females. The female wasp oviposits in spiderlings presence of skins. all the a uloborid spider's egg-case, and the larvae wasp pupal Although spider are killed in a the consume the contents of the spider's eggs, eggs parasitized egg-case, are still visible and were used to leaving behind empty spider egg shells. The egg-shells infer the clutch size. wasp larvae then pupate inside the spider egg- original structure: I noted the size and or- case and emerge as adults. If an egg-case is Colony of all communal formed parasitized, all of the spider eggs inside are ganization groups by each in several locations: P. oweni in killed (Smith 1982). species Cave Creek Canyon (1977), South Fork Can- METHODS yon (1979, 1980) and Herb Martyr (1980); P. Observations and collections were made at arizonica in South Fork Canyon (1979, 1980). several sites in the Chiricahua Mountains in Feeding rates: From 21-27 August 1979, I southeastern Arizona: the Southwestern Re? compared feeding rates of solitary and com? search Station of the American Museum of munal females of the two species in South Natural History; South Fork Canyon, Cave Fork Canyon using a trapline census method. Creek Canyon, and Herb Martyr Reservoir in Censuses were carried out from 0600-1800 h. the Coronado National Forest; and the town Daily census periods were 4-6 h long, for a of Portal (Cochise County). total of 29 h of observation. Every hour I vis- Population censuses: Adult females and ited each female in the study area and record? some males were individually color-marked ed whether or not she was feeding or engaged with dots of fast-drying enamel paints (Tes- in prey capture. tor's model airplane paint) and censused 2-5 Web structure: In July and August of 1980 times per week. From 25 April-20 August I measured the webs of all adult females 1977 I censused a marked population of P. found in the South Fork Canyon study area: oweni in Cave Creek Canyon at an elevation 22 webs of P. oweni and 19 webs of P. ari? of approximately 1695 m. This population zonica. I measured longest diameter of the orb was destroyed by a flood in 1978. From 3 webs and deviation (to the nearest 10?) of the June-18 September 1979 I censused marked plane of the orb webs from horizontal, and populations of P. oweni and P. arizonica in counted number of radii and number of spiral South Fork Canyon. The P. arizonica popu? turns along the longest radius. I also noted the lation was located in the lower part of the can? amount and position of "space webbing" (ir- yon (1525-1660 m) while the P. oweni pop? regular tangles of threads), the presence or ab? ulation was in the upper part of the canyon sence of a stabilimentum and the general ap- (1630-1730 m). At each census visit I noted pearance of the webs. the presence of adult females, males, imma? Habitat: To evaluate the distribution of the tures or egg-cases. two species with respect to elevation I located SMITH?NOTES ON PHILOPONELLA 13

* Table 1.?Phenological data for Philoponella oweni and Philoponella arizonica. Still active when field observations ended.

all collection sites (eight for P. oweni, six for Table 3. Both tables show that P. oweni fe? P. arizonica) on a topographical map. I also males produce fewer egg-cases per female and recorded the substrates used for web attach? lay more eggs per egg-case than do P. arizon? ment by members of each species. In July and ica females. The behavior of females with August 1977 I recorded the substrates used for egg-cases also differs between the two spe? 25 P. oweni webs in Cave Creek Canyon, and cies. in August 1979 I recorded the substrates of 36 A female P. oweni about to construct an P. oweni and 31 P. arizonica webs in South egg-case leaves her prey-capture orb and Fork Canyon (in each case, this represented moves to the retreat area, a protected area near all adult webs present in the study sites). the orb usually under a rock or log, and con- Egg-cases: In July 1980 I collected 24 emp- structs the egg-case there. There she remains, ty P. oweni egg-cases and 33 empty P. ari? holding the egg-case and (presumably feeding zonica egg-cases and measured maximum little or not at all) until the young emerge, a width and length to the nearest mm using dial period of approximately 20 days. After the calipers, and noted their color, shape and or- young emerge the mother discards the egg- namentation. case, leaves the retreat, and spins a new prey capture-orb. P. oweni females usually have RESULTS one or at most two egg-cases at a time. The Population censuses: Table 1 gives the time interval between successive egg-cases dates of first sightings of age and sex classes produced by a female is more than a week, of both species. These data are limited by the typically 2-3 weeks. starting and finishing dates of the censuses, In contrast, females of P. arizonica were but still show differences between adjacent never seen to leave the orb with their egg- populations of P. oweni and arizonica. P. ow? cases. These females suspend their spindle- eni adults appear sooner (at a given altitude) shaped egg-cases from the hub of their hori- and adult P. oweni males disappear from these zontal orbs. As new egg-cases are constructed, populations by late June and early July. Adults at intervals of 4-10 days, they are attached to of P. arizonica appear later, and the adult the egg-cases already hanging in the web to males persist in populations until late July. form a long, slender stick (Fig. 1). The female There was little temporal overlap between P. continues feeding while the eggs and young oweni males and P. arizonica females in ad? mature. P. arizonica females sometimes have jacent populations. as many as 8 egg-cases in the web at Reproductive biology: Table 2 presents data once. Egg-case parasitism by the wasp A. on reproductive parameters for all females in dasys (Fig. 2) is a major source of mortality the study areas, whether or not complete re- in both species. In general, a higher proportion cords of their reproductive history could be of the egg-cases of P. arizonica than of P. made. In 1979 I had complete reproductive oweni are attacked by egg-case parasites. In histories for 31 P. oweni females and 25 P. 1979, 14% of the egg-cases produced by P. arizonica females. These data are presented in oweni females and 27% of the egg-cases pro- 14 THE JOURNAL OF ARACHNOLOGY

Table 2.?Reproductive parameters for Philoponella oweni and Philoponella arizonica, Cave Creek Canyon in 1977 and South Fork Canyon in 1979. Statistical tests are for differences between adjacent a Philoponella oweni and Philoponella arizonica populations in South Fork Canyon in 1979. = Mann b = Whitney ?/-test; two-tailed /-test for samples with equal variance, 13.5; r 3.21, 1 dfi d, x1 = 7.10, 1 df; e, Mann Whitney ?/-test.

duced by P. arizonica females were parasit? individual females (Table 3). Mean lifetime = ized (this difference is not significant; x2 egg production by P. oweni and arizonica fe? 3.21, 1 df Table 2). For females for whom males did not differ significantly, nor did complete reproductive histories were recorded mean lifetime production of live spiderlings (Table 3), significantly more egg-cases of P. (Mann Whitney ?/-test). However, 19% of P. arizonica than of P. oweni were parasitized. oweni females (6 of 31) lost all of their eggs Similarly, for all females and for females with to parasites, while only 4% of the P. arizonica complete reproductive records, a higher pro? females (1 of 25) was similarly affected. = portion of P. arizonica females than P. oweni While this difference is not significant (x2 females lost at least one egg-case to parasites. 2.9, 1 df), it does suggest that P. arizonica's Because the average clutch size of P. oweni habit of packaging lifetime egg production females is larger than that of P. arizonica fe? into many small clutches may reduce the risk males, the appropriate comparison of repro? of losing an entire lifetime of egg production ductive effort and reproductive success is life- to parasites. time egg and spiderling production of A comparison can also be made between

Table 3.?Lifetime reproductive parameters for Philoponella oweni and P. arizonica for whom complete a b life histories are known (South Fork Canyon, 1979). = Mann Whitney U-test; = two-tailed r-test for c samples with equal variance, t = -1.73; \2 = 18.16, 1 df, d, x2 ~ 8.16, 1 df e, Mann Whitney U-test.

Mean SD Median Range <0.001a

0.09b (ns)

0.00002c

0.0043d

0.9 le (ns) SMITH?NOTES ON PHILOPONELLA 15

served with at least one egg case, the figures are 2.9 ?1.6 egg cases per solitary female (n = 32 females), 3.61 ? 2.5 per communal fe? male (n = 18 females; t = 1.15, P < 0.26, 48 df). Colony structure: Both species occur in sol? itary webs and in aggregations. The aggrega- tions of both species contain two or more adult females, each with her own prey capture orb. The aggregations formed by the two spe? cies differ in severai respects. Colonies of P. oweni attained larger size than those of P. arizonica: the largest P. ow? eni colony observed contained 44 adult fe? males plus males and immatures. The mean number of females per web site at various lo- cations were: Cave Creek Canyon 1977, 3.5? = ? SD 8.6 (range 1-44, n 25 web sites, 879); South Fork Canyon, 1979, 1.7 9 SD ? = 2.0 (range 1-11, n 52 web sites, 879); and on Philo? Figure 2.?Arachnopteromalus dasys Herb Martyr, 1979, 1.39 ? SD 0.6 (range 1- oweni ponella egg-cases. 4, n = 40 web sites, 539). In P. oweni colonies, orbs of adults and im? the solitary and group-living members of each matures share support lines. The orbs are ar- species. It was reported earlier (Smith 1982) ranged side by side in loose sheets of orbs, that on average, communal females P. oweni and severai orbs or sheets of orbs may be produced more eggs per egg case than solitary stacked one over the other. Retreat(s) are not females, though they did not differ in mean specially constructed by colony members; number of egg cases per female (1977: soli? they are simply protected areas near the web tary females, 26.9 SD ?13 eggs per egg case, such as a cleft under a rock or log surrounded n = 13 cases; communal females, 37.3 ? 15.1 by old webbing. The retreat or retreats may = = eggs per egg case, n 38 egg cases, t 2.17, be used in common by all colony members. P < 0.05. 1979: solitary females 44.3 ? 15.3 Aggregations of P. arizonica are smaller = eggs, n 26 cases; communal females 56.1 and simpler. The largest aggregation ever ob? = = ? 17.0 eggs, n 24 cases, t 2.57, P < served (in 1980) contained eight adult fe? 0.05). males. In 1979 the mean number of females/ In P. arizonica, no difference was observed web site in South Fork Canyon was: 1.7 ? = in the number of eggs per egg case produced SD 1.2 (range 1-6, n 45 web sites, 769). by solitary and communal females: solitary Males and immatures may also be present in = females, 21.5 ? 9.1 eggs per egg case, n aggregations. The webs in an aggregation are 69 cases; communal females, 22.2 ? 8.61 side by side, joined by their space webbing. = eggs, n 42 cases. Because females in this Retreats are usually absent. species make a large number of egg cases, it Feeding rates: Females of P. oweni spent a is difficult to be sure all egg cases are noted greater proportion of time feeding during the and collected; thus estimating the mean num? census period. On average 41.7 ? SD 17.8% ber of egg cases per female is difficult. Given of P. oweni females and 26.5 ? SD 11.7% of these caveats, there does not appear to be any P. arizonica females were feeding per census significant difference in number of egg cases hour (29 h, 10-13 P. oweni females, 17-20 = per female. For all females, the mean number P. arizonica females, P 0.0009, Mann of (observed) egg cases per female was 2.35 Whitney U-test). These measurements can be = ?1.9 for solitary females (n 40 females), broken down to compare the feeding rates of 2.6 ? 2.7 for communal females (n = 25 fe? solitary and aggregated females. In P. oweni males; t = 0.44, P < 0.66, 63 df, two-tailed an average of 53.1 ? SD 22.9% of communal test, equal variances). For those females ob- females were feeding per census hour (6-8 fe- 16 THE JOURNAL OF ARACHNOLOGY

Table 4.?Web measurements for Philoponella oweni and Philoponella arizonica; n - 22 webs of adult female Philoponella oweni, 19 webs of adult female P. arizonica. (Significance determined by two-tailed Mest for samples with equal variance).

males). This is significantly more than the the hub, giving it a slightly domed appear- time spent feeding by any other class of fe? ance. In many orbs the radials are not all in = males (29 h, P 0.001 or less, Mann Whitney one plane, giving the orb a pleated appear- U-test). There was no significant difference ance. None of these webs had stabilimenta. = among the other three classes (P 0.40 or Habitats: In August 1980 all populations of more, Mann Whitney U-test): solitary P. ow? P. oweni sampled were found at an elevation eni, 22.9 ? SD 22.2% females feeding per of 1630 m or higher (1630-1950 m) while all = hour, n 2-5 females; aggregated P. arizon? populations of P. arizonica were below 1630 ica, 28.7 ? SD 15.7% females feeding per m (1460-1630 m). The P. oweni webs were = hour, n 7-10 females; solitary P. arizonica, usually built in protected locations such as = 25.2 ? SD 15.4% feeding per hour, n 7-11 hollow trees and clefts between rocks. The P. females. arizonica webs were built in more open areas, Web structure: Web measurements are pre? such as in brush, shrubs or grass (Table 5). sented in Table 4. Female P. oweni construct Egg-cases and immatures: The two species relatively large orbs which are closer to ver- differ in the structure of their egg-cases. Phil? tical than horizontal. There is a small quantity oponella oweni constructs large beige or co- of space webbing below and around the orb, coa-colored stellate egg-cases which are but there is seldom any above the orb. Stabi- more-or-less flat on one side and domed on limenta are usually present. The web P. ari? the other (Fig. 1). The mean length of the 24 zonica consists of a small horizontal orb sur- egg cases measured was 6.7 mm (SD ? 0.96, rounded above, below and around the edges range 5.2-5.8 mm); mean width was 4.4 mm with space webbing. The orb is sometimes (SD ? 0.61, range 2.9-5.4 mm). These cases drawn up in the center by threads attached to are heavily decorated with small spikes of

Table 5.?Substrates used for web construction by Philoponella oweni and Philoponella arizonica: 1977, a Cave Creek population; 1979, South Fork Canyon populations. Yucca schottii absent from site. SMITH?NOTES ON PHILOPONELLA 17

silk, especially on the curved side (spikes on Among P. arizonica, there was no differ? flat side: median 5, range 0-22; spikes on ence in the feeding rates of solitary and com? curved side: median 13, range 5-24). Philo? munal females?both were similar to the feed? ponella arizonica constructs pale smooth, ing rates of solitary P. oweni. No insect whitish or bone colored egg-cases (Fig. 1). trapping was done in the vicinity of P. ari? These cases are spindle-shaped, and there are zonica colonies and solitary webs, so it is not usually no decorations or projections (of 33 possible to say if insect abundance differs be? egg-cases only eight were decorated with tween the sites of colonies and solitary webs. spikes, ranging in number from 7-12). Mean The earlier report on communal behavior of length of the 33 egg cases measured was 7.4 P. oweni also showed that females in com? mm (SD ? 1.1, range 5.1-9.1 mm); mean munal groups produced a greater number of width was 2.8 mm (SD ? 0.30, range 2.2-3.4 eggs per egg case than did solitary females, mm). though total live young per female was the The immatures of the two species are also same for the two groups due to higher rates recognizably different. P. oweni immatures of egg case parasitism in the communal are black with white markings and P. arizon? groups (Smith 1982). One explanation for this ica immatures are yellow with brown mark? difference could be the difference in feeding ings. rates between solitary and communal females. We observed no significant difference be? DISCUSSION tween solitary and communal P. arizonica ei? Philoponella oweni and P. arizonica are ther in number of eggs per egg case or in egg found in close proximity in both time and cases per female, which dovetails with the space and occupy similar habitats. Although feeding rates observed. However, as noted they are similar in appearance, they can easily above, there are problems in collecting data be distinguished in the field by structure of the on the number of egg cases per female in this orb webs, nature of the communal groups species. Additional comparative study of the (where they exist), the form of the egg cases reproductive biology of communal and soli? and the coloration of second instar spiderlings. tary Philoponella is warranted. They also tend to use different substrates for Over their lifetimes, females of the two spe? web construction, with P. oweni making use cies produce the same average number of eggs of rigid substrates such as fallen logs, hollow and the same number of live second instar spi? trees, and niches under rocks, and P. arizonica derlings. However the two species differ in the making greater use of vegetation such as way they package their eggs and care for the shrubs, grasses and yuccas as substrate. egg cases. P. oweni females package their An enhanced food supply (whether due to eggs in one or a few large packets and make higher prey capture rate, reduced prey han- what appears to be a large expenditure in pa- dling time, increased size of prey, or other fac- rental care, in the form of guarding the egg- tors) has often been proposed as a benefit of case without feeding. The females of P. ari? group-living behavior in spiders (e.g., Binford zonica, on the other hand, package their eggs & Rypstra 1992, Buskirk 1975, 1981; Nen? into many small packets and continue to feed twig 1985; Rypstra 1979, 1990). This study in their orbs while the egg-cases are suspend- showed an interesting difference in feeding ed in the web. rates of the solitary and communal females P. Both species are subject to the same egg oweni and P. arizonica. As was reported ear- parasite, Arachnopteromalus dasys. It is not lier (Smith 1983), among P. oweni the pro? clear if the different egg-case tending behav? portion of females feeding per hour was great? iors of P. oweni and P. arizonica have any er for communal than for solitary females. effect against egg parasites such as Arachnop? Insect trapping at the sites of communal and teromalus dasys. One might suppose that the solitary P. oweni webs indicated that insect behavior of P. oweni affords more protection abundance was greater at sites occupied by than that of P. arizonica. However another colonies than at sites occupied by single webs. uloborid spider, Uloborus glomosus (Wal? This suggests that communal groups are fea- ckenaer 1841), also makes severai small-egg sible at sites where insect abundance is high cases which it attaches to the web. In this spe? enough to support several females. cies, the female has been observed to jerk the 18 THE JOURNAL OF ARACHNOLOGY

web and make leg sweeping motions in re? parasitism on unguarded P. arizonica and P. sponse to parasitoid (and spiderlings) oweni egg-cases to rates of parasitism on un- crawling on the egg-cases (Cushing 1989; manipulated egg-cases. Cushing & Opell 1990), though it is not clear Hypothesis 4: P. arizonica is subject to a how effective this is in deterring parasites. I risky, unpredictable environment. The P. ari? have observed A. dasys crawling on the egg- zonica pattern of reproduction ensures that at cases of both P. oweni and P. arizonica with least some of a female's offspring may hatch no obvious reaction from the mothers of eggs. at a time when conditions are favorable. One It is possible to make some testable hy- obvious possibility is that spiderlings require potheses concerning the adaptive significance a supply of very small prey, and that the avail? (or lack of it) of the Philoponella egg-case ability of these insects varies unpredictably tending behaviors. These hypotheses fall into over time. Little is known about the feeding four categories: those dealing with uncertain- behavior and survivorship of spiderlings. A ties faced by the female, those dealing with first step would be to examine feeding behav? uncertainties faced by the young, those which ior and prey of hatchlings, record variation in consider differences in clutch size as side-ef- juvenile feeding rates over time, and correlate fects of other maternal behaviors, and non- fluctuations in feeding rate with fluctuations adaptive explanations. in environmental factors such as rainfall. Hypothesis 1: P. arizonica females face Hypothesis 5: The differences in reproduc? more uncertainties in food supply than P. ow? tive behaviors are not adaptations to any dif? eni females. When they gather enough re- ferences in ecology, behavior or microhabitat. sources for a small batch of eggs they produce Each species is conservative in behavior and a clutch right away; if they were to wait for displays the maternal behavior typical of its additional prey they might use up their small closest relatives. The first step in testing this reserve of energy in maintenance activities. hypothesis would be to construct a phylogeny This can be tested by measuring the feeding for species in the Philoponella semiplumosa rates of marked individuals over time. P. ar? species group (Opell 1979, 1987), and exam? izonica females would be expected to have a ine the maternal behavior of the closest rela? higher variance in feeding rate than P. oweni tives of P. oweni and P. arizonica species. females. ACKNOWLEDGMENTS Hypothesis 2: P. arizonica females are sub- ject to a high and constant probability of mor- I thank Brent Opell for identification of tality over their adult lives, while P. oweni Philoponella oweni and P. arizonica speci? Willis females have relatively low probability dying mens, and Gertsch and Vincent Roth for and I before the first clutch is laid. It doesn't pay a encouragement advice while was at the Southwestern Research P. arizonica female to save up resources for working station. a large clutch if there is a good chance she Robert Hagen provided useful criticism of the will die before it can be laid. Life history data, manuscript. This research was supported in particularly from the early part of the breeding part by grants from the Theodore Roosevelt Memorial of the season, are needed to test this hypothesis. Fund American Museum, Hypothesis 3: Females of P. oweni must Sigma Xi National, and Sigma Xi Cornell this was of guard their egg-cases because predators and chapter. Long ago, study part my egg-parasites are more common in their en- doctoral research at Cornell University. I am vironment than in that of P. arizonica. It sorry that my advisor and friend, Dr. George did would be more economical to produce a single C. Eickwort, not live to see the last chap? large clutch than many small ones, since it ter of my thesis published. takes as much time and to a energy guard LITERATURE CITED small egg-case as a large one. This assumes Binford, G. & A.L. Rypstra. 1992. Foraging be? that the type of maternal care shown by the havior of the communal Philoponella re- is more effective than that spider, bag species actually publicana (Araneae: Uloboridae). J. Insect Be? of the P. in arizonica females preventing par- hav., 5:321-355. asitism or . This can be tested by re- Breitwisch, R. 1989. Prey capture by a West Af- moving females from egg-cases, leaving the rican social spider (Uloboridae: Philoponella egg-cases in situ, and comparing the rates of sp.). Biotropica, 21:359-363. SMITH?NOTES ON PHILOPONELLA 19

Buskirk, R.E. 1975. Coloniality, activity patterns Opell, B.D. 1979. Revision of the genera and trop- and feeding in a tropical orb-weaving spider. ical American species of the spider family Ulo- Ecology, 56:1314-1328. boridae. Bull. Mus. Comp. Zool., 148:443-549. Buskirk, R.E. 1981. Sociality in the Arachnida, Pp. Opell, B.D. 1987. The new species Philoponella 282-367, In Social Insects, Vol. II.(H.R. Herman, herediae and its modified orb web (Araneae, ed.). Academic Press, New York. Uloboridae). J. Arachnol., 15:59-63. Cushing, PE. 1989. Possible egg sac defense be? Rypstra, A.L. 1979. Foraging flocks of spiders: A haviors in the Uloborus spider glomosus (Ara? study of aggregate behavior in Cyrtophora citri- neae: Uloboridae). Psyche, 96:269-277. cola Forskal (Araneae; Araneidae) in West Af- Cushing, P.E. & B.D. Opell. 1990. Disturbance be? rica. Behav. Ecol. Sociobiol., 5:291-300. haviors in the Uloborus spider glomosus (Ara? Rypstra, A.L. 1990. Prey capture and feeding ef- neae, Uloboridae): avoidance possible predator ficiency of social and solitary spiders: a compar? Canadian J. 68:1090-1097. strategies. Zool., ison. Acta Zool. Fennica, 190:339-343. Eberhard, W.G. 1977. The webs of newly emerged Smith, D.R. 1982. Reproductive success of solitary Uloborus diversus and of a male Uloborus sp. and communal Philoponella oweni (Araneae: (Araneae: Uloboridae). J. Arachnol., 4:201-206. Uloboridae). Behav. Ecol. Sociobiol., 11:149- Gordh, G. 1976. A new of Pteromalidae genus 154. from Missouri, the type species of which para- Smith, D.R. 1983. Ecological costs and benefits of sitizes Uloborus octonarius Muma (Hymenop? communal behavior in a Behav. tera: Chalcidoidea; Araneida: Uloboridae). J. presocial spider. Ecol. 13:107-114. Kansas Ent. Soc, 49:100-104. Sociobiol., D.R. Lahmann, E.J. & W.G. Eberhard. 1979. Factores Smith, 1985. Habitat use by colonies of Phil? J. selectivos que afectan la tendencia a agruparse oponella republicana (Araneae: Uloboridae). en la arana colonial Philoponella semiplumosa Arachnol., 13:363-373. (Araneae; Uloboridae). Rev. Biol. Trop., 27:231- Szlep, R. 1961. Developmental changes in the 240. web-spinning instinct of Uloboridae: construc? Muma, M.M. & WJ. Gertsch. 1964. The spider tion of the primary type web. Behaviour, 27:60- family Uloboridae in North America north of 70. . Amer. Mus. Novitates, 2196:1-43. Nentwig, W. 1985. Social spiders catch larger prey: a study of Anelosimus eximius (Araneae: Theri- Received 28 February 1995, revised 10 October diidae). Behav. Ecol. Sociobiol., 17:79-85. 1996.