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

ANELOSIMUS SIMON, 1891

Anelosimus Simon, 1891 , 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 , 7G, H , 19E ). 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 ). Most Anelosimus differ from other theridiids in genitalia: having conspicuous ridges on the epigynal plate ( Fig. 31A ), a subconductor present in the male palp ( Fig. 33C, D ), and an incised mesal cymbial distal margin ( Fig. 33A ). 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 , 14E , 24C , 34D ), 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 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 , 43D , 46C ), clypeus flat, its height usually about three times AME diameter ( Fig. 43E ). Eyes subequal in size, lateral eyes touching ( Figs 19E , 37C ), anterior row usually slightly procurved, posterior row slightly recurved ( Figs 32F , 41F , 48F ). Sternum extending between fourth coxae, tapered ( Figs 15B , 24D ). Chelicerae with three (usually) to four teeth on anterior margin ( Figs 14D , 38F , 51F ), the mesal-most one largest, others subequal, 3–6 equalsized denticles on posterior margin ( Figs 3D , 5F , 12G ). Abdomen ovoid, longer than wide ( Fig. 7G, H ), hirsute ( Fig. 31C, D , 32G , 41D ), with a diagnostic dorsal bandlike, hatched, folium, dark centrally (red in live specimens), bordered by a narrow white rim ( Figs 7G, H , 19E ). Abdominal apodemes (muscle attachments), fairly indistinct, smooth, or slightly rugose ( Fig. 54B, C ). Pedicel inserted anteriorly or medially (abdomen then appearing ‘higher than long’) on the abdomen ( Figs 1E , 31C , 34B ). Stridulatory apparatus on abdomen conspicuous in males ( Figs 34D , 38C ), with stridulatory picks consisting of raised setal basis ( Fig. 47F ), in distinctly curved, paired, rows dorsal to the pedicel ( Fig. 24C , 41C , 43C , 46D , 50F ) often asymmetric, and stridulatory nubbins interspersed in between ( Fig. 32D ). Stridulatory picks less pronounced in females ( Figs 34C , 37D ). Prosomal ridges, interacting with stridulatory picks, inconspicuous, irregular and shallow ( Fig. 15A ). Colulus absent, two colular setae present ( Figs 31E , 51E ). Spinnerets with typical theridiid spigots ( Figs 26G , 51A–D , 53D–F ): anterior lateral spinnerets with a major ampullate and 30–45 piriform spigots ( Figs 12C , 32A , 38D , 54F ), posterior median spinnerets with a minor ampullate spigot, a cylindrical spigot (female) and two aciniform spigots ( Fig. 31F , 38E ), posterior lateral spinnerets with two enlarged and flattened aggregates, a flagelliform, two cylindrical (female), and 3–15 aciniform spigots ( Figs 14C , 31F ). Cylindricals absent, and aggregate and flagelliform spigots reduced to nubbins in males ( Figs 12D , 43F , 54G, H ). Anal tubercle as in Figure 34G . Epiandrous gland spigots in two groups, sometimes placed in distinct sockets ( Figs 3A , 5D , 10E , 11F , 14B , 18E , 22C , 24A , 48C , 54A ). Usually 5–15 spigots in each group, number variable between and within species, often asymmetric within a specimen ( Figs 31B , 37B , 41B , 43B , 50G ). Female leg length formula usually 1423, male usually 1243. Femur I of male often more robust than other femora ( Fig. 26F ), typically somewhat curvy ( Fig. 41G ); in some species femur I is not robust ( Fig. 46E ). Several (usually 4–8) small trichobothria dorsally on all tibia ( Fig. 53G, H ), usually three on palpal tibia (rarely four or more, e.g. Figs 2F , 43G ) of both male ( Figs 29F , 47D ) and female ( Figs 31C, E , 32E ). Central tarsal claw elongate on tarsus IV, especially so in males ( Figs 15E , 32B , 38B ), relatively short on other legs ( Figs 18F , 22H , 34E , 43H , 46F ). Accessory claws distinct, especially on tarsus IV ( Fig. 48E ). Female palpal claw straight, densely dentate, tarsal ventral setae serrate ( Fig. 38A ). Typical theridiid tarsal comb on female tarsus IV ( Fig. 41E ). Venter of tarsus I ( Fig. 22E , 38G ), and tip of metatarsus I ( Fig. 22F ) 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 ). One pair of seminal receptacles, usually showing clearly through the cuticle ( Fig. 16C ). Copulatory ducts usually simple, often distinctly sclerotized proximally ( Fig. 27F,G ), fertilization ducts short and simple, curving towards each other. Palpus ( Fig. 28A– F ) 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 , 29A–F , 30A–E ). Subconductor forms a pit ( Fig. 30B ) into which the lobed tail of the embolus, or a part of the embolus spiral, fits. Cymbium constricted mesally ( Fig. 29A ), usually with a distal lightly sclerotized tip. Cymbial process hooded, distally on ectal margin ( Figs 18A , 30B ).

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 ). Webs may be somewhat amorphous, following the contour of the vegetation (e.g. Fig. 66A, D ). Sticky silk usually not visible in webs.

Egg sacs dull grey, spun densely with fine silk strands ( Fig. 37E, F ), 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 ). 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 (Heteroptera, Miridae ) is common in Anelosimus 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 and Faiditus also commonly occur in Anelosimus webs, their numbers generally increasing with colony size and longevity ( Avilés & Tufiño, 1998; see also Agnarsson, 2003b). Some are species specific; F. ululans for example specializes on A. eximius nests ( Cangialosi, 1990a,b). As many as 10% of the adult spiders of an Anelosimus colony may be kleptoparasites.

Commercial damage? Stejskal (1976) suggested that some Anelosimus 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).

Figures

Figure 1. The ‘analyticus group’. A–E, Anelosimus analyticus. A, male palp mesal; B, same, ventral view; C, epigynum; D, internal epigynum dorsal; E, male habitus. F–I, Anelosimus chickeringi. F, male palp mesal; G, same, ventral view; H, epigynum; I, internal epigynum dorsal; J, female abdomen. K–O, Anelosimus pacificus. K, male palp mesal; L, same ventral view; M, epigynum; N, internal epigynum dorsal; O, digital photograph of spermathecal area of cleared epigynum.

Figure 2. Anelosimus analyticus, male palp. A, dorsal; B, submesal; C, ventral, note the small embolic division b (Eb), and the cymbial hood (upper arrow). In this species the embolic lobe fits snugly under the subconductor (SC); D, ectal; E, apical view of tip, mesal side; F, part of palpal tibia, unusually with four trichobothria (arrows). Scale bars: A–D, 100 µm; E,F, 50 µm.

Figure 3. Anelosimus analyticus. A, epiandrous gland spigots; B, epigynum; C, male stridulatory pick row (left); D, female cheliceral promarginal teeth; E, female spinnerets; F, female abdomen ectal view; G, female abdominal surface. Scale bars: A–E,G, 20 µm; F, 100 µm.

Figure 5. Anelosimus chickeringi. A, male pedicel area; B, female pedicel area; C, epigynum; D, epiandrous gland spigots; E, female carapace dorsal; F, female promarginal cheliceral teeth. Scale bars: A,B, 50 µm; C,D,F, 10 µm; E, 100 µm.

Figure 7. The ‘domingo group’. A–D, Anelosimus domingo. A, male palp mesal; B, same ventral; C, epigynum; D, internal epigynum dorsal. E–J, Anelosimus jabaquara. E, male palp submesal; F, same ventral; G, female abdomen; H, male habitus; I, epigynum; J, internal epigynum dorsal. K–P, Anelosimus dubiosus. K, male palp mesal; L, same ventral; M, epigynum; N, internal epigynum dorsal; O, digital photograph of internal epigynum dorsal; P, male first leg.

Figure 10. Anelosimus domingo. A–D, female. A, epigynum; B, posterior lateral spinneret, anterior is left; C, clypeus; D, carapace; E, epiandrous gland spigots; F, male stridulatory pick row. Scale bars: A,F, 50 µm; B,E, 10 µm; C,D, 100 µm.

Figure 11. Anelosimus jabaquara. A–E male palp. A, dorsal; B, ventral; C, apical; D, palpal tip; E, palpal tibia; F, epiandrous gland spigots; G, epigynum. Scale bars: A–E, 100 µm; F, 10 µm; G, 50 µm.

Figure 12. Anelosimus jabaquara. A–D, male. A, stridulatory pick row; B, pedicel area, ectal view, showing proprioreceptic setae; C, anterior lateral spinnerets, anterior is left; D, posterior median and posterior lateral spinnerets; E–G, female. E, female prosoma profile; F, ocular region and clypeus; G, cheliceral promargin, anterior view, both promarginal teeth and retromarginal denticles are visible. Scale bars: A,G, 20 µm; B,E,F, 100 µm; C,D, 10 µm.

Figure 14. Anelosimus dubiosus. A, epigynum; B, epiandrous gland spigots; C, female posterior median and posterior lateral spinnerets; D, female prolateral cheliceral teeth; E, male stridulatory pick row; F, male prosoma dorsal; G, female prosoma dorsal. Scale bars: A,D,F,G, 100 µm; B, 20 µm; C, 10 µm; E, 50 µm.

Figure 15. Anelosimus dubiosus. A, male prosomal stridulatory ridges; B, female sternum; C, male prosoma; D, female prosoma; E, male fourth tarsal claws; F, female tip of fourth tarsus; G, female palpal tibia, as typical for Anelosimus with three dorsal trichobothria (arrows). Scale bars: A–D, 100 µm; E, 20 µm; F,G, 50 µm.

Figure 16. Anelosimus eximius. A, male palp mesal; B, same ventral; C, epigynum; D, internal epigynum, ventral, the complex folding is difficult to interpret and the pathway of the fertilization duct remains poorly understood; E, female habitus.

Figure 18. Anelosimus eximius. A, distal part of cymbium of an expanded palp, note the wrinkled tip (arrow); B, male stridulatory pick row, right side; C, female left spinning field; D, epigynum; E, epiandrous gland spigots; F, male second tarsal claws; G, female prosoma dorsal. Scale bars: A,D,G, 100 µm; B,C, 50 µm; E, 10 µm.

Figure 19. The ‘jucundus group’. A–E, Anelosimus arizona. A, male palp mesal, arrow points to the eb-ridge, larger in this species than in any other Anelosimus; B, same ventral; C, epigynum; D, internal epigynum dorsal; E, female habitus. F–I, Anelosimus jucundus. F, male palp mesal; G, same ventral; H, epigynum; I, internal epigynum dorsal. J–N, Anelosimus octavius. J, male palp expanded, mesal; K, male palp ventral; L, male palp expanded, ectal; M, epigynum; N, internal epigynum dorsal.

Figure 22. Anelosimus arizona. A, epigynum ventral; B, epigynum subcaudal; C–H, male. C, epiandrous gland spigots; D, stridulatory pick row; E, tarsus I ventral; F, metatarsus I ventral; G, details of thick setae on metatarsus I; H, tarsus I claws. Scale bars: A,B,D,G 100 µm; C, 50 µm; H, 10 µm.

Figure 24. Anelosimus jucundus. A, epiandrous gland spigots; B, epigynum; C, male stridulatory pick row; D, female prosoma ventral; E, female prosoma dorsal; F, male prosoma dorsocaudal. Scale bars: A, 50 µm; B–F, 100 µm.

Figure 26. Anelosimus octavius. A, epigynum; B, epiandrous gland spigots; C, male stridulatory pick row, note dorsally angled, mesally orientated, picks (arrows); D, female prosoma dorsal; E, female prosoma front; F, male carapace with leg I and femur IV; G, female left spinning field. Scale bars: A,C–G 100 µm; B, 50 µm.

Figure 27. The ‘jucundus group’. A–M, Anelosimus baeza. A, male palp mesal, from Baeza, Ecuador; B, same, ventral view; C, male palp ventral, from Colombia; D, epigynum, from Baeza, Ecuador; E–G, epigynum, from Las Caucheras, Ecuador. E, ventral view; F, internal epigynum, ventral; G, internal epigynum dorsal; H, male habitus, from Baeza; I, male habitus, from Las Cuacheras; J, female habitus, from Las Caucheras; K, same, profile; L, ectal view of male abdomen, from Baeza; M, ectal view of male abdomen, from Las Caucheras. N–Q, Anelosimus puravida. N, male palp mesal; O, same, ventral; P, epigynum; Q, internal epigynum dorsal.

Figure 28. Anelosimus baeza from Baeza, male palp. A, mesal; B, ventral; C, subectal, note the ectal tegular process (arrow); D, ectal; E, details of conductor and embolus tip, ventral; F, same, mesal view. Scale bars: A–D, 100 µm; E,F, 50 µm.

Figure 29. Anelosimus baeza from Las Caucheras, male palp. A, dorsoapical view; B, mesal; C, submesal, apical view; D, ventral, note a conspicuous ectal tegular process (arrow); E, details of conductor, subconductor and embolus tip, ventral; F, palpal tibia, with three trichobothria (arrows). Scale bars: 100 µm.

Figure 30. Anelosimus baeza, male palp expanded. A, mesal view; B, submesal, the arrow indicates the subconductor hood; C, dorsal; D, ectal; E, details of embolus. Scale bars: 100 µm.

Figure 31. Anelosimus baeza from Las Caucheras. A, epigynum; B, epiandrous gland spigots; C–F, female. C, abdomen ventral; D, abdomen surface; E, colular setae; F, posterior median and posterior lateral spinnerets. Scale bars: A,C,D, 100 µm; B,E, 50 µm; F, 10 µm.

Figure 32. Anelosimus baeza from Las Caucheras. A, female anterior lateral spinnerets; B, male fourth tarsal claws; C, female palp; D, male stridulatory pick row, arrows indicate a couple of the stridulatory nubbins interspersed in the area between the rows of picks; E, female palpal tibia; F, female cephalic region; G, male abdomen ventral. Scale bars: A,B, 10 µm; C–G, 100 µm.

Figure 33. Anelosimus puravida, male palp. A, dorsomesal view; B, apical, submesal; C, ventral; D, ectal, tip of palpus; E, apical, tip of palpus; F, details of embolus tip and conductor. Scale bars: 100 µm.

Figure 34. Anelosimus puravida. A–C, female. A, epigynum; B, abdomen ventral; C, abdominal pedicel area. D, male stridulatory pick row, right side; E, female fourth tarsal claws; F, female prosoma dorsal; G, male anal tubercle. Scale bars: A–C,F, 100 µm. D, 20 µm; E,G, 10 µm.

Figure 37. Anelosimus tosum. A, epigynum; B, epiandrous gland spigots; C, female prosoma dorsal; D, female stridulatory pick row; E, egg sac fibres; F, higher magnification of egg sac fibres. Scale bars: A,C–E, 100 µm; B,F, 10 µm.

Figure 38. Anelosimus tosum. A, female palpal claw. B–G, male. B, fourth tarsal claws; C, stridulatory pick row; D, anterior lateral spinneret; E, posterior median spinnerets, anterior view; F, cheliceral promarginal teeth; G, first tarsus ventral. Scale bars: A,C,F, 50 µm; B, 20 µm; D,E, 10 µm; G, 100 µm.

Figure 41. Anelosimus oritoyacu. A, epigynum; B, epiandrous gland spigots; C, male stridulatory pick row; D, female abdomen surface; E, female tarsus IV; F, female prosoma dorsal; G, male femur I. Scale bars: A,D,F,G, 100 µm; B, 20 µm; C,E, 50 µm.

Figure 43. Anelosimus tungurahua. A, epigynum; B, epiandrous gland spigots; C, male stridulatory pick row; D, female prosoma dorsal; E, same, front; F, male spinnerets, anterior is left; G, female palpal tibia dorsal; H, male tarsus I claws. Scale bars: A,B,F, 50 µm; C–E, 100 µm; G,H, 20 µm.

Figure 46. Anelosimus elegans. A, epigynum; B, epiandrous gland spigots; C, female prosoma dorsal; D, male stridulatory pick row; E, male prosoma and leg I; F, male tarsus I claws. Scale bars: A,C–E, 100 µm; B, 50 µm; F, 10 µm.

Figure 47. Anelosimus guacamayos. A–E male palp. A, mesal; B, apical; C, ventral; D, ectocaudal, arrows indicate the tibial trichobothria; E, details of embolus tip and conductor. F, male stridulatory pick row, right side. Scale bars: A–D, 100 µm; E,F, 20 µm.

Figure 48. Anelosimus guacamayos. A,B, epigynum. A, ventral; B, subcaudal. C, epiandrous gland spigots; D, female palpal tibia, dorsal view showing the three trichobothria (arrows); E, female fourth tarsal claws, central claw removed – note strong accessory claws (arrows); F, female cephalic region. Scale bars: A,B,F, 100 µm; C,E, 20 µm; D, 50 µm.

Figure 50. Anelosimus studiosus. A–E, male palp. A, mesal; B, ventral; C, ectal; D, details of embolus tip; E, tibia, note three trichobothria (arrows). F, male stridulatory pick row; G, epiandrous gland spigots; H, epigynum. Scale bars: A–C, 100 µm; E,H, 50 µm; D,F,G, 20 µm.

Figure 51. Anelosimus studiosus female. A, spinnerets; B, anterior lateral spinneret, anterior is right; C, posterior lateral, and posterior median spinnerets, right side; D, posterior median spinnerets, submesal view; E, colular setae (arrow), note absence of colulus; F, cheliceral teeth posterior view. Scale bars: A,E,F, 100 µm; B–D, 20 µm.

Figure 53. Anelosimus pantanal, female. A, epigynum ventral; B, epigynum, different specimen from same colony; C same, anterior view. D–F, spinnerets. D, all; E, anterior lateral spinneret, anterior is right; F, posterior lateral and posterior median spinnerets. G, fourth tibia, bearing six dorsal trichobothria (arrows); H, third tibia, bearing five dorsal trichobothria (arrows). Scale bars: A–D, 50 µm; E, 10 µm; F, 20 µm; G,H, 100 µm.

Figure 54. Anelosimus pantanal. A, epiandrous gland spigots; B, male booklung cover; C, male abdominal apodeme; D, male stridulatory pick row; E, female stridulatory pick row; F, anterior lateral spinneret; G, posterior lateral spinneret, right side; H, posterior median spinnerets, anterior is right. Scale bars: A,F–H, 10 µm; B,C, 100 µm; D, 50 µm; E, 20 µm.

Figure 66. Anelosimus webs, all from Ecuador. A, A. studiosus; B, A. guacamayos; C, A. eximius; D, A. oritoyacu; E, A. domingo.