Anelosimus, SIMON, 1891

Agnarsson, Ingi, 2006, A revision of the New World eximius lineage of Anelosimus (Araneae, Theridiidae) and a phylogenetic analysis using worldwide exemplars, Zoological Journal of the Linnean Society 146 (4), pp. 453-593 : 473-478

publication ID	https://doi.org/ 10.1111/j.1096-3642.2006.00213.x
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ANELOSIMUS SIMON, 1891 View in CoL View at ENA

Anelosimus Simon, 1891 View in CoL , 60: 11. Type species: Anelosimus socialis Simon, 1891 (= Theridium eximium Keyserling, 1884 ).

Diagnosis: Anelosimus can be readily diagnosed by the abdomen colour pattern: a dark (in alcohol, often red in life specimens) notched longitudinal central band edged by a narrow, notched, white band, and bilateral white blotches distributed outside the dorsal band ( Figs 1J View Figure 1 , 7G, H View Figure 7 , 19E View Figure 19 ). Anelosimus differs from most theridiids (except some hadrotarsines, and perhaps Chrosiothes ) in lacking a colulus, but a pair of colular setae are present ( Fig. 31E View Figure 31 ). Most Anelosimus differ from other theridiids in genitalia: having conspicuous ridges on the epigynal plate ( Fig. 31A View Figure 31 ), a subconductor present in the male palp ( Fig. 33C, D View Figure 33 ), and an incised mesal cymbial distal margin ( Fig. 33A View Figure 33 ). The organization of abdominal stridulatory picks, although variable, is also diagnostic, usually a conspicuous curved A. studiosus B refers to populations studied by Brach (1977), F to populations studied by Furey (1998). Sex ratio is indicated at females per male (f/m). Maximum colony size is estimated from the literature, not applicable (n/a) for solitary species. Stage of development at dispersal is estimated from the literature, number indicates instar, not counting moults inside the egg sac. Maternal care (beyond care of egg sac) is defined as provisioning by mother after the spiderlings emerge from the egg sac. Sibling co-operation (and adult co-operation) is defined as shared effort towards a common task. Regurgitation indicates mother donating predigested food. Multiple females refers to nests containing more than one adult female. Adult tolerance implies absence of aggression between (unrelated) females sharing a web. Tolerance to introduced aldults indicates lack of aggression to unrelated (introduced) adult females. Female non-brood care indicates females indiscriminately caring for young (own or those of other females) in the nest. Overlapping generations indicates co-occurrence and co-operation of mother and her adult offspring, even though brief. Non-reproductive females indicates the presence of adult females partaking in the tasks of the colony, but failing to reproduce themselves. Question marks indicate unknowns, ‘x’ a rare behaviour, ‘X’ a common behaviour, and ‘some’ indicates presence of behaviour in some populations.

row of picks with the distalmost distinctly compressed ( Figs 5A View Figure 5 , 14E View Figure 14 , 24C View Figure 24 , 34D View Figure 34 ), sometimes a straight row of very numerous picks (see Agnarsson, 2004: fig. 26D,E). As in most theridiids, females have much weaker picks (e.g. Figs 5A View Figure 5 versus 5B, 54D versus 54E). Finally, most Anelosimus differ from other theridiids in building communal webs, usually sheet like with knockdown-threads, sometimes irregular meshes.

Description: Small- to medium-sized theridiids (1.8– 7.5 mm total length). Prosoma longer than wide, pear shaped ( Figs 19E View Figure 19 , 43D View Figure 43 , 46C View Figure 46 ), clypeus flat, its height usually about three times AME diameter ( Fig. 43E View Figure 43 ). Eyes subequal in size, lateral eyes touching ( Figs 19E View Figure 19 , 37C View Figure 37 ), anterior row usually slightly procurved, posterior row slightly recurved ( Figs 32F View Figure 32 , 41F View Figure 41 , 48F View Figure 48 ). Sternum extending between fourth coxae, tapered ( Figs 15B View Figure 15 , 24D View Figure 24 ). Chelicerae with three (usually) to four teeth on anterior margin ( Figs 14D View Figure 14 , 38F View Figure 38 , 51F View Figure 51 ), the mesal-most one largest, others subequal, 3–6 equalsized denticles on posterior margin ( Figs 3D View Figure 3 , 5F View Figure 5 , 12G View Figure 12 ). Abdomen ovoid, longer than wide ( Fig. 7G, H View Figure 7 ), hirsute ( Fig. 31C, D View Figure 31 , 32G View Figure 32 , 41D View Figure 41 ), with a diagnostic dorsal bandlike, hatched, folium, dark centrally (red in live specimens), bordered by a narrow white rim ( Figs 7G, H View Figure 7 , 19E View Figure 19 ). Abdominal apodemes (muscle attachments), fairly indistinct, smooth, or slightly rugose ( Fig. 54B, C View Figure 54 ). Pedicel inserted anteriorly or medially (abdomen then appearing ‘higher than long’) on the abdomen ( Figs 1E View Figure 1 , 31C View Figure 31 , 34B View Figure 34 ). Stridulatory apparatus on abdomen conspicuous in males ( Figs 34D View Figure 34 , 38C View Figure 38 ), with stridulatory picks consisting of raised setal basis ( Fig. 47F View Figure 47 ), in distinctly curved, paired, rows dorsal to the pedicel ( Fig. 24C View Figure 24 , 41C View Figure 41 , 43C View Figure 43 , 46D View Figure 46 , 50F View Figure 50 ) often asymmetric, and stridulatory nubbins interspersed in between ( Fig. 32D View Figure 32 ). Stridulatory picks less pronounced in females ( Figs 34C View Figure 34 , 37D View Figure 37 ). Prosomal ridges, interacting with stridulatory picks, inconspicuous, irregular and shallow ( Fig. 15A View Figure 15 ). Colulus absent, two colular setae present ( Figs 31E View Figure 31 , 51E View Figure 51 ). Spinnerets with typical theridiid spigots ( Figs 26G View Figure 26 , 51A–D View Figure 51 , 53D–F View Figure 53 ): anterior lateral spinnerets with a major ampullate and 30–45 piriform spigots ( Figs 12C View Figure 12 , 32A View Figure 32 , 38D View Figure 38 , 54F View Figure 54 ), posterior median spinnerets with a minor ampullate spigot, a cylindrical spigot (female) and two aciniform spigots ( Fig. 31F View Figure 31 , 38E View Figure 38 ), posterior lateral spinnerets with two enlarged and flattened aggregates, a flagelliform, two cylindrical (female), and 3–15 aciniform spigots ( Figs 14C View Figure 14 , 31F View Figure 31 ). Cylindricals absent, and aggregate and flagelliform spigots reduced to nubbins in males ( Figs 12D View Figure 12 , 43F View Figure 43 , 54G, H View Figure 54 ). Anal tubercle as in Figure 34G View Figure 34 . Epiandrous gland spigots in two groups, sometimes placed in distinct sockets ( Figs 3A View Figure 3 , 5D View Figure 5 , 10E View Figure 10 , 11F View Figure 11 , 14B View Figure 14 , 18E View Figure 18 , 22C View Figure 22 , 24A View Figure 24 , 48C View Figure 48 , 54A View Figure 54 ). Usually 5–15 spigots in each group, number variable between and within species, often asymmetric within a specimen ( Figs 31B View Figure 31 , 37B View Figure 37 , 41B View Figure 41 , 43B View Figure 43 , 50G View Figure 50 ). Female leg length formula usually 1423, male usually 1243. Femur I of male often more robust than other femora ( Fig. 26F View Figure 26 ), typically somewhat curvy ( Fig. 41G View Figure 41 ); in some species femur I is not robust ( Fig. 46E View Figure 46 ). Several (usually 4–8) small trichobothria dorsally on all tibia ( Fig. 53G, H View Figure 53 ), usually three on palpal tibia (rarely four or more, e.g. Figs 2F View Figure 2 , 43G View Figure 43 ) of both male ( Figs 29F View Figure 29 , 47D View Figure 47 ) and female ( Figs 31C, E View Figure 31 , 32E View Figure 32 ). Central tarsal claw elongate on tarsus IV, especially so in males ( Figs 15E View Figure 15 , 32B View Figure 32 , 38B View Figure 38 ), relatively short on other legs ( Figs 18F View Figure 18 , 22H View Figure 22 , 34E View Figure 34 , 43H View Figure 43 , 46F View Figure 46 ). Accessory claws distinct, especially on tarsus IV ( Fig. 48E View Figure 48 ). Female palpal claw straight, densely dentate, tarsal ventral setae serrate ( Fig. 38A View Figure 38 ). Typical theridiid tarsal comb on female tarsus IV ( Fig. 41E View Figure 41 ). Venter of tarsus I ( Fig. 22E View Figure 22 , 38G View Figure 38 ), and tip of metatarsus I ( Fig. 22F View Figure 22 ) with series of small, bent tipped, setae, absent on other tarsi (similar setae are widespread in theridiids, and particularly densely grouped in some hadrotarsines, see Agnarsson, 2004). These setae are presumably sensory; recognition (e.g. kin vs. prey) often involves touch with the first pair of legs.

Males of some permanently social species about half the size of females or less, but only very slightly smaller than females in other species.

Epigyna lightly sclerotized, epigynal plate distinctly depressed, usually bearing conspicuous ridges ( Fig. 53B View Figure 53 ). One pair of seminal receptacles, usually showing clearly through the cuticle ( Fig. 16C View Figure 16 ). Copulatory ducts usually simple, often distinctly sclerotized proximally ( Fig. 27F,G View Figure 27 ), fertilization ducts short and simple, curving towards each other. Palpus ( Fig. 28A– F View Figure 28 ) with a median apophysis without a hood, a hooked theridiid tegular apophysis, large spiralling embolus and usually a small to tiny conductor, resting on a subconductor (e.g. Figs 28A–F View Figure 28 , 29A–F View Figure 29 , 30A–E View Figure 30 ). Subconductor forms a pit ( Fig. 30B View Figure 30 ) into which the lobed tail of the embolus, or a part of the embolus spiral, fits. Cymbium constricted mesally ( Fig. 29A View Figure 29 ), usually with a distal lightly sclerotized tip. Cymbial process hooded, distally on ectal margin ( Figs 18A View Figure 18 , 30B View Figure 30 ).

Webs usually basket shaped, a more or less domed sheet, reinforced with dead (or sometimes living) leaves, with aerial strands leading upwards that intercept prey in flight ( Fig. 66B, E View Figure 66 ). Webs may be somewhat amorphous, following the contour of the vegetation (e.g. Fig. 66A, D View Figure 66 ). Sticky silk usually not visible in webs.

Egg sacs dull grey, spun densely with fine silk strands ( Fig. 37E, F View Figure 37 ), appearing papery. Egg sacs are deposited and guarded in the web, but when moved, females carry egg sacs in the chelicerae.

Phylogenetics: (see above)

Composition: Anelosimus currently contains 53 described species: A. agnar Agnarsson, 2006 , A. analyticus , A. andasibe Agnarsson & Kuntner, 2005 , A. arizona , A. baeza , A. biglebowski Agnarsson, 2006 , A. chickeringi , A. chonganicus Zhu, 1998 , A. crassipes Bösenberg & Strand, 1906 , A. decaryi (Fage, 1930) , A. dialeucon ( Simon, 1890) , A. domingo , A. dubiosus , A. dubius , A. dude Agnarsson, 2006 , A. elegans , A. ethicus , A. exiguus Yoshida, 1986 , A. eximius , A. fraternus , A. guacamayos , A. inhandava Agnarsson, 2005 , A. iwawakiensis Yoshida, 1986 , A. jabaquara , A. jucundus , A. kohi Yoshida, 1993 , A. linda Agnarsson, 2006 , A. lorenzo , A. may , A. misiones Agnarsson, 2005 , A. monskenyensis Agnarsson, 2006 , A. nazariani , A. nelsoni A. nigrescens ( Keyserling 1884) , A. octavius , A. oritoyacu , A. pacificus , A. pantanal , A. placens ( Blackwall, 1877) , A. pulchellus , A. puravida , A. rabus , A. rupununi , A. sallee , A. salut Agnarsson & Kuntner, 2005 , A. studiosus , A. sulawesi Agnarsson, 2006 , A. sumisolena Agnarsson, 2005 , A. taiwanicus Yoshida, 1986 , A. tosum , A. tungurahua , A. vittatus (C. L. Koch 1836) and A. vondrona Agnarsson & Kuntner, 2005 .

Distribution: Worldwide, found on all continents except Antarctica. Most speciose in tropical areas, many species occur at altitudes of 1000−2800 m, a number of species are coastal.

Natural history: Anelosimus species range from showing extended maternal care (subsocial, e.g. A. arizona ) to permanent, co-operative adult web-sharing (social, e.g. A. eximius ) (see Avilés, 1997, for a review). Some species (including A. pacificus and A. ethicus ) may be solitary. Co-operation is most extensive in social species and includes collaborating in web construction, prey capture, feeding, defence and in some instances co-operative brood care (including care of offspring of other females). The primary benefit of group living appears to be an increase in the probability of offspring survival ( Avilés & Tufiño, 1998), coupled with avoiding the cost of dispersal ( Uetz & Hieber, 1997). Social species are also able to handle larger prey than solitary species of a similar size ( Christenson, 1984; Nentwig, 1985; Nentwig & Christenson, 1986).

Levels of sociality and inter- and intraspecific variation. As discussed elsewhere social categories (subsocial, social) are approximations, broad terms used to generalize about the range of characteristics that make a species ‘social’. A closer look indicates variation, both inter- and intraspecific, in individual components of sociality forming more of a continuum than discrete categories of sociality.

Brach (1977) after studying A. studiosus in Florida came to the conclusion that ‘ A. studiosus social behavior consists almost entirely of subsocial elements’ (p. 160) its colonies lasting only a season and almost exclusively composed of a mother and her brood, most of which disperse prior to or just after mating. However, Furey (1998) showed that some populations of A. studiosus in Tennessee form longer lasting nests with multiple egg-laying females and moderately biased sex ratio (about 3.2 females per male). Nentwig and Christenson (1986) studied ‘ A. jucundus ’ (most likely A. baeza , see below), and considered it to be ‘more social’ than A. studiosus (as described by Brach, 1977), showing greater adult–adult tolerance and some generation overlap. L. Avilés & W. P. Maddison (pers. comm.), however, found that allopatric populations of A. baeza differ and the range of social behaviour in A. baeza includes both extremes described for A. studiosus by Brach (1977) and Furey (1998).

Marques et al. (1998) compared the level of sociality in A. dubiosus and A. jabaquara in Brazil. They found that although most A. jabaquara formed singlemother/offspring colonies, some colonies had two to several adult egg-laying females. In the latter case the females showed aggression towards one another while guarding egg sacs, but at around the time the mothers started dying (brood instar IV) the broods of different mothers started mixing. Most A. jabaquara dispersed away from their natal nest as subadults, or adults, before mating. The sex ratio in A. jabaquara was slightly female biased (1.8 females per male). A. dubiosus formed multi-female colonies more commonly than A. jabaquara . The females guarded their own egg sacs, but showed less aggression than A. jabaquara towards other adults in the web (both in natural conditions and when adult females were introduced into established webs). Brood-mixing took place by the second instar, after which they were fed indiscriminately by regurgitation by any adult female (or even an older juvenile) in the nest. Co-operation in web building started earlier and was more extensive in A. dubiosus than in A. jabaquara and only a portion of individuals dispersed away from the natal nest prior to mating. The sex ratio of A. dubiosus was slightly more female biased with 3.2 females per male. Recently, Gonzaga and Vasconcellos-Neto (2001) described A. jabaquara populations in which juveniles commonly remained in the natal nest to mate and rear brood. The probability of emigration correlated positively with size. In this species seasonal rupture of social structure thus seems not to be obligatory.

The ‘level’ of sociality displayed by members of the genus Anelosimus therefore varies continuously between and even within species. One extreme is populations/species exclusively consisting of a mother and her progeny who co-operate until dispersal at or near maturity, and the other, species such as A. eximius with multiple egg-laying females in huge communal webs that last several generations and contain hundreds to thousands of spiders.

Colonies. Webs of most Anelosimus species , whether subsocial or social, are similar. Typically the webs contain a tough basket-shaped sheet, enforced with dead leaves and debris, and with aerial threads extending upwards that intercept insects in flight ( Fig. 66A–E View Figure 66 ). Sometimes the sheet may be divided into several tiers or silk platforms, perforated by silk reinforced holes ( Brach, 1975). Smaller nests of subsocial species usually occur in open areas (hillsides, along paths and rivers, etc.) at the ends of branches, often in clusters. Social nests of most species occur along rivers, in clearings and in forest edges, while A. domingo nests primarily occur in the forest understory. Social webs often beset the vegetation and cover bushes or even entire tree canopies. Very large webs may lose the ‘basket-shape’ and rather follow the contour of the vegetation. Webs of some species (e.g. A. rupununi and A. lorenzo ) are irregular meshes that lack aerial threads; these species forage below the sheet.

New subsocial colonies are established by dispersing individuals (subadults or young adults). In social species new colonies can also be formed by swarms of individuals, or by colony ‘budding’, i.e. a large colony splitting into two or more smaller colonies. Social colonies may last several generations, whereas in subsocial species colonies typically last one generation. Subsocial nests, however, may last more than one generation as the first female to mature may remain in the natal nest, but drive her female siblings out of the nest ( Brach, 1977).

Colonies contain anywhere from about 20 (small subsocial nests) to several tens of thousands of individuals (large social nests) ( Avilés, 1997; Avilés & Tufiño, 1998; Venticinque et al., 1993). Colony size and survival depend on many factors. In A. eximius , offspring survival increased with colony size, while individual female reproductive output was highest at intermediate colony size, and risk of parasitism was higher the larger the colony ( Avilés & Tufiño, 1998). Therefore, individual fitness seems to be highest at intermediate colony size.

Daily ‘routine’. The spiders spend most of the day ‘resting’ under the dead leaves incorporated into the sheet of the web, or ‘patrolling’ the sheet ( Brach, 1975, 1977). Activity is lowest around noon, but high at dusk.

When a prey item hits the sheet and tries to struggle free, the vibrations alert nearby nest members (in large nests most prey items only draw the attention of a small portion of the nest members), who attack the prey. Usually larger individuals (adult females, subadults) attack first, typically first swathing larger prey with sticky silk (so called ‘wrap attack’), before delivering bites on the extremeties. Smaller individuals then join, and also bite the prey, often at the tip of the legs. The prey is then consumed communally, and nest members not involved in the killing may also feed on the prey. In A. eximius the prey is approached in a synchronized and rhythmical fashion, bursts of activity alternated with periods of immobility ( Krafft & Pasquet, 1991). The synchronized ‘silence’ periods help to isolate the vibrations coming from the struggling prey and thus facilitate prey catching.

Another task that draws the spiders out of their retreats is web construction. The sheet is fixed by patching; sheet repair may be done individually or communally and seemingly can take place at any time during (at least) the night. Aerial thread building is more synchronized. In some species the spiders ritually swarm up the aerial threads on a daily basis, typically in the late afternoon or early nighttime. Presumably the spiders are laying new aerial threads or reinforcing pre-existing ones.

During rain, patrolling, web-building or feeding individuals quickly return to their retreats.

Tolerance and co-operation. Mothers show extensive maternal care in Anelosimus colonies. Maternal care includes guarding the egg sac (individual egg sacs, or groups of egg sacs of different mothers as in A. rupununi ), regurgitative feeding of young in many species and provisioning offspring with killed, predigested, prey items ( Avilés, 1997). Juveniles start contributing to the colony early, and typically all colony members (excluding adult males) co-operate. Cooperation includes collective prey catching, web building, defence, communal feeding, egg sac guarding, and in the most social species, co-operative care of the brood. In social species intraspecific tolerance seems to be universal, with apparent absence of nest-specific recognition mechanisms ( Tapia & de Vries, 1980; Avilés & Tufiño, 1998). Recognition of conspecifics is primarily tactile (with apparent secondary loss of conspecific recognition via vibration); nest members frequently exchange touches with the pair of first legs, but show no aggression ( Brach, 1975). Heterospecific spiders do generally not induce aggression by the vibrations they cause walking on the web (unlike struggling prey), but are recognized by touch and are then attacked. In subsocial species tactile cues are apparently less important than in social species. Rather, conspecific recognition is via vibrations, and heterospecific spiders may be detected from distance and attacked ( Brach, 1977). Tolerance is also less stereotypic. Subsocial siblings collaborate in the natal nest until dispersal, but tolerance and co-operation break down with age (adults are aggressive towards one another) and when food is scarce. In a laboratory experiment under conditions of crowding or low food supply, co-operation broke down among subsocial juveniles and the spiders readily cannibalized each other ( Avilés & Gelsey, 1998). Tolerance can also be artificially prolonged in subsocial species, by supplementing colonies with food ( Krafft, Horel & Julita, 1986; Ruttan, 1990; Gundermann, Horel & Krafft, 1993).

Sex ratios. At odds with Fisher’s (1930) general rule of equal sex ratios, sex ratios are female biased in many of the eximius lineage species. Brach (1975) attributed this bias to differential cannibalism on males. Avilés (1986, 1987, 1993), Avilés & Maddison (1991) and Avilés et al. (2000), however, showed that the primary sex ratio itself is biased and that males are not disproportionately cannibalized. In A. eximius , for example, the sex ratio is strongly biased with about 10% of subadults and 9% of embryos being males ( Tapia & de Vries, 1980; Avilés, 1986; Avilés & Maddison, 1991). The sex ratio bias in Anelosimus seems to be correlated with the level of sociality – the ‘more social’ the greater the bias (see Table 2).

According to the ‘local mate competition’ idea ( Hamilton, 1967) sex ratio bias can be expected when populations are subdivided into reproductive units, and especially when mating occurs among siblings. As long as a male is available to fertilize his sisters, mothers gain by producing mostly females; additional males would only compete for mates but not increase the number of second-generation progeny. However, others have argued that female-biased sex ratios are selected for by the differential contribution of genetically different groups to the population’s gene pool ( Colwell, 1981; Wilson & Colwell, 1981). The importance of interdemic selection in explaining biased sex ratios is much debated (e.g. Borgia, 1982; Charlesworth & Toro, 1982; Nunney, 1985; Wilson, Pollock & Dugatkin, 1992), especially in systems where singlemother offspring interact briefly (e.g. fig wasps). Avilés (1986, 1993, 1997), however, argued that in the social spiders, interdemic selection is powerful enough to override individual selection, mainly because only colonies above some threshold size proliferate (benefiting faster growing colonies), and rate of colony extinction is very high (hence many selection events at the colony level). Using computer simulations, Avilés (1993) showed that in multi-female nests lasting many generations, individual selection acted towards equal sex ratios, and sex ratio bias could only be maintained by selection at the colony level: Colonies producing more females grew faster and left more daughter colonies in the next generation.

The mechanisms used to bias the sex ratio in Anelosimus are not understood, but in at least one species, sex ratios appear precisely biased, implying a sperm sorting mechanism ( Avilés et al., 2000). In A. domingo , the primary sex ratio is biased with approximately 9.3 females per male. Egg sacs contain between nine and 22 embryos and by chance many egg sacs should lack male embryos. Yet every egg sac examined by Avilés et al. (2000) contained at least one male embryo; in this species males are thus allocated to clutches with significantly greater precision than expected by chance.

Parasitism. Various organisms parasitize Anelosimus individuals, their eggs and their colonies. Parasites include both endoparasites (e.g. nematodes), ectoparasites (hymenopterans) and kleptoparasites (true bugs, spiders).

I am unaware of any research on Anelosimus endoparasites, but occasional museum specimens contain a nematode, typically in the abdomen. Hymenopteran ectoparasites appear to be common. Females lay their egg on the abdomen of the spider and the whitish-yellow larva feeds on the spider as it grows. In some Anelosimus colonies, most or all of the colony members are parasitized in this manner (my pers. obs.). In orb-weavers at least one such parasite induces behavioural changes where the host abandons normal web-building and instead makes a cocoon web for the host’s larvae ( Eberhard, 2000, 2002).

In A. eximius , one-quarter of the egg sacs are parasitized on average, the risk increasing with colony size ( Avilés & Tufiño, 1998). Generally very small colonies have no parasites, whereas larger ones usually do and the parasite load can reach an amazing 100%.

Most Anelosimus species have communal or kleptoparasitic organisms occupying their nests (e.g. Cangialosi, 1990a, b). The plant bug genus Ranzovius View in CoL (Heteroptera, Miridae View in CoL ) is common in Anelosimus View in CoL nests, and different Ranzovius species seem to specialize on particular Anelosimus species ( Henry, 1984, 1999; Wheeler & McCaffrey, 1984; Nentwig, 1985). Argyrodine spiders of the genera Argyrodes View in CoL and Faiditus View in CoL also commonly occur in Anelosimus View in CoL webs, their numbers generally increasing with colony size and longevity ( Avilés & Tufiño, 1998; see also Agnarsson, 2003b). Some are species specific; F. ululans View in CoL for example specializes on A. eximius nests ( Cangialosi, 1990a,b). As many as 10% of the adult spiders of an Anelosimus View in CoL colony may be kleptoparasites.

Commercial damage? Stejskal (1976) suggested that some Anelosimus View in CoL pierce the epidermis of mango, citrus and coffee leaves and drink from them. Some Anelosimus species reach very high densities in orchards, and may eventually kill the vegetation by shading ( Stejskal, 1976).