Amaurobioidea

Zorocrates aemulus, copyright Marshal Hedin.

Belongs within: Neocribellatae.
Contains: Stiphidiidae, Agelenidae, Amphinectidae, Desidae, Zodariidae, Amaurobiidae, Cycloctenidae, Pisauridae, Oxyopidae, Lycosidae, Dionycha.

The Amaurobioidea have historically been recognised as including cribellate spiders with unbranched median tracheae but such a grouping is now recognised as non-monophyletic. Instead, ‘amaurobioids’ represent basal members of what is commonly referred to as the RTA clade, referring to the presence of a retrolateral tibial apophysis on the male palp. Nested within this clade are the Lycosoidea, a clade of mostly actively hunting spiders united by a notably recurved posterior eyerow and grate-shaped tapeta in the anterior lateral and posterior median eyes (Ramírez 2014). The Indo-Australian Psechridae are lycosoids with a narrow, divided cribellum and a calamistrum consisting of three or four rows of equal, short, distally bent setae (Jocqué & Dippenaar-Schoeman 2007).

The Zorocratidae, found in southern North America and Madagascar, have a large tegular apophysis occupying the greater part of the ventral surface of the male palp, and the embolus originating on the dorsal surface of the palpal bulb and extending behind the bulb for its length. The Tengellidae, found in the Americas and New Zealand, are medium-sized to large spiders with three tarsal claws, often with claw tufts, a distally notched labium and two rows of similarly sized trichobothria on the tarsi (Jocqué & Dippenaar-Schoeman 2007).

Amaurobioidea: rummaging through a wastebasket
Published 18 August 2008
A representative of the strikingly-coloured Nicodamidae from Australia. Photo by Nick Monaghan. While such spiders were previously identified as Nicodamus bicolor, there are no less than 23 species in seven genera that have previously been included under that name.

One term that you may come across in discussions of phylogeny is the concept of a “wastebasket” taxon. As the name suggests, a wastebasket taxon is one into which authors tend to throw everything that they can’t really deal with. Often, a wastebasket will include the members of a group that are relatively unspecialised, often primitive, and united less by their shared characters than their lack of distinct features to connect them to one or another of the specialised subgroups that the author may recognise within the parent group. Phalangodidae among short-legged harvestmen, Sylviidae among passerine birds and Perciformes among spiny-finned fishes are all examples of taxa that have become wastebaskets in the past. Some wastebasket taxa are explicitly established as such, like the ‘Deuteromycota’ that included asexual fungi before techniques were developed that made it significantly easier to relate asexual and sexual fungal taxa. More often, though, a taxon originally based on a certain combination of features will develop into a wastebasket over time as phylogenetic studies show that the original basis characters for that taxon represent plesiomorphies (ancestral characters). This page’s highlight taxon, the spider superfamily Amaurobioidea, perhaps belongs to the latter group.

Tegenaria gigantea (Agelenidae). Photo from Wikipedia. Agelenids build funnel-shaped webs and are apparently often called some variant of “funnel spiders” in North America, but such names are likely to cause confusion here in Australia with a certain notorious mygalomorphs. Some species of Tegenaria such as the hobo spider are also known for being toxic, but nowhere near as toxic as the Australian funnel-web.

Elsewhere, I provided a quick overview of basal spider phylogeny, going as far down as the clade Araneoclada that unites those spiders that have only a single pair of book lungs (ancestrally, at least—many families of Araneoclada have lost the book lungs entirely, or evolved tracheae in their place). Members of the Araneoclada are further divided between the Haplogynae and the Entelegynae, originally based on the presence (Entelegynae) or absence (Haplogynae) in females of paired copulatory ducts opening on a sclerotised plate called the epigyne. While the absence of such ducts in the Haplogynae is obviously a primitive character and no longer regarded as uniting them, the group has funnily enough been supported as monophyletic based on a number of other characters (except for a small number of ‘haplogyne’ taxa that are phylogenetically entelegynes) (Coddington & Levi 1991). However, the Amaurobioidea belong to the Entelegynae, which is by far the larger of the two clades. Within the Entelegynae, the primary division was long based on whether or not a species possessed a cribellum, a plate-like structure among the spinnerets that bears hundreds of tiny silk-producing spigots. As these spigots exude silk simultaneously, the spider uses a specialised arrangement of bristles on the fourth pair of legs to weave them together to form a woolly thread. Because this woolly thread is composed of multiple tangled strands, it can effectively entangle prey such as small insects that get caught among the strands. Unfortunately, as knowledge of entelegyne spiders improved it became clear that possession of a cribellum did not define a phylogenetically coherent group. A number of cases were identified of pairs of taxa clearly related by other characters in which one taxon possessed a cribellum and the other did not. The eventual conclusion was that the cribellum was an ancestral character for the Entelegynae (as also supported by its presence in one haplogyne family, the Filistatidae) that had been lost on numerous occassions.

Ctenus floweri (Ctenidae), from Singapore. Photo by David Court. Ctenids are active hunters.

In general, the Amaurobioidea included cribellate spiders with unbranched abdominal median tracheae, as opposed to Dictynoidea with branched abdominal median tracheae (Coddington & Levi 1991). Families that have been assigned to Amaurobioidea include (among others) Amaurobiidae, Agelenidae, Ctenidae, Amphinectidae and Nicodamidae, but relatively little unites these families. Most of them are generally ground-dwellers (which may explain the common name of one of the best-known members, the hobo spider Tegenaria agrestis). Many members build small sheet-webs, but others are active hunters. Both the characters referred to above have since been shown to represent plesiomorphies of larger clades, with the alternative conditions arising multiple times. The phylogenetic analysis of entelegyne spiders by Griswold et al. (1999) found the ‘Amaurobioidea’ to fall within a clade that was sister to the clade including the orb-weavers, but the same clade included the Dictynoidea and Lycosoidea (wolf spiders and such) nested within ‘amaurobioids’. Indeed, not even the type family of Amaurobiidae was monophyletic, with some members closer to the lycosoids while others were closer to the agelenoids. The Amaurobioidea, it seems, were a bust.

The running of the spiders
Published 7 March 2015
Nursery-web spider Dolomedes minor, sitting atop its nursery web, copyright Konstable.

Spiders are one of the most familiar groups of invertebrates out there. There’s no denying this: everybody knows what a spider is. But for various reasons, the classification of spiders tended to lag a bit behind that of other terrestrial invertebrates. Being softer-bodied than insects, they tend not to exhibit the wealth of features that made many insect groups instantly discernible. To the modern arachnologist’s eye, the earliest classifications of spiders can verge on the humorous. Latreille (1802), in his Histoire Naturelle des Crustacés et des Insectes, classified the entirety of what would now be called the araneomorph spiders into a single genus Aranea, divided into sections labelled not with formal names but with schematic diagrams of the arrangement of eyes found in that section.

A few decades later, in 1829 (translated into English in Cuvier, 1831), Latreille was to present a more detailed classification of the spiders, in which they were divided into groups largely on the basis of their life habits. The araneomorphs were hence divided between the Sedentariae, those spiders which captured their prey in webs or laid in ambush, and the Vagabundae, those spiders that actively hunted down their prey. The Vagabundae were in turn divided between two sections: the Citigradae or runners, and the Saltigradae or jumpers. Latreille’s classification was subsequently more or less abandoned, as his behavioural groupings failed to line up directly with morphological clusters. Almost by accident, however, those taxa included by Latreille in his Citigradae have continued to be associated, and in modern classifications are classified within the Lycosoidea (Jocqué & Dippenaar-Schoeman 2007).

The lycosoids are, indeed, mostly active hunters. Their behaviour is reflected in the vernacular names of a number of the constituent families: the wolf spiders of the Lycosidae, the lynx spiders of the Oxyopidae, the prowling spiders of the Miturgidae. But the correspondence to Latreille’s ‘araignées loups’ is not perfect: the Zoropsidae, for instance, are lycosoids that spin extensive webs. Nor are they mere rapacious hunters: many are devoted parents, carrying and/or guarding their egg-sacs to protect them from predators, and in the case of the Lycosidae even providing a certain degree of care for the newly hatched spiderlings.

One group of lycosoids has even gotten a name for parental care. The nursery-web spiders of the Pisauridae construct protective webs for their babies, containing them within a tent constructed by wrapping sheets of silk around suitable vegetation. When I was a child in New Zealand, I used to be fascinated by the nursery webs constructed by the species Dolomedes minor. Like many pisaurids, this species is associated with water, diving into it to hunt for fish and other small aquatic animals. The females would often build their nursery webs by tying together the ends of nearby rushes. Though it seems a little cruel to my adult self, the younger me loved to pull these webs apart to see the eruption of tiny spiders come scurrying out.

Systematics of Amaurobioidea

Synapomorphies (from Ramírez 2014, as RTA clade): Carapace thoracic fovea a narrow dark longitudinal line; general metatarsal spination pattern x-x-x; more than two metatarsal trichobothria on a leg; tarsus with single trichobothrial row.

<==Amaurobioidea [Agelenoidea, Citigradae]R14
|--+--Pimus Chamberlin 1947R14, WZ08
| | `--P. napaR14
| `--+--StiphidiidaeR14
| `--+--AgelenidaeR14
| `--+--+--AmphinectidaeR14
| | `--DesidaeR14
| `--+--ZodariidaeJD-S07
| |--AmaurobiidaeR14
| `--CycloctenidaeR14
`--+--LycosoideaR14
| |--PsechridaeJD-S07
| | |--Eomatachia latifrons Petrunkevitch 1942S93
| | |--Fecenia Simon 1887JD-S07
| | | `--F. oblonga Rainbow 1913R13
| | `--Psechrus Thorell 1878JD-S07 [incl. Lancaria Karsch 1879K92]
| | |--P. argentatus (Dol. 1857) [=Tegenaria argentata; incl. T. torva Cambr. 1870, Lancaria torva]K92
| | `--P. singaporensisJD-S07
| `--LycosaeformiaJD-S07
| |--+--PisauridaeR14
| | `--+--Senoculus Taczanowski 1875R14, JD-S07 [Senoculidae]
| | `--OxyopidaeR14
| `--+--LycosidaeJD-S07
| `--TrechaleidaeJD-S07
| |--Syntrechalea brasilia Carico 2008FM11
| |--EnnaJD-S07
| `--Trechalea Thorell 1870JD-S07
| |--T. biocellataMC05
| `--T. keyserlingiCM07
`--+--TengellidaeR14
| |--Anachemmis Chamberlin 1919JD-S07
| |--Calamistrula Dahl 1901JD-S07
| |--Titiotus Simon 1897JD-S07
| |--AustrotengellaR14
| |--AnachemmisR14
| |--Socalchemmis Platnick & Ubick 2001JD-S07
| | `--S. idyllwildR14
| |--Tengella Dahl 1901JD-S07
| | `--T. radiataJD-S07
| `--Wiltona Koçak & Kemal 2008PVD10 [=Haurokoa Forster & Wilton 1973 (preoc.)PVD10, JD-S07]
| `--*W. filicicola (Forster & Wilton 1973) [=*Haurokoa filicicola]PVD10
`--+--*Ciniflella luteaR14
`--+--Zorocratidae [Zorocratinae]BS09
| |--Zorodictyna Simon 1907GC99, JD-S07
| |--Uduba Simon 1880GC99, JD-S07
| |--Campostichomma Karsch 1891GC99, JD-S07
| | `--*C. manicatum Karsch 1892K92
| `--Zorocrates Simon 1888R14, JD-S07
| |--Z. aemulusR14
| |--Z. fuscusBS09
| |--Z. gnaphosoidesR14
| `--Z. unicolorR14
`--+--+--DionychaR14
| `--Liocranoides Keyserling 1881R14, JD-S07
| `--L. unicolorR14
`--+--Raecius Simon 1898R14, JD-S07
| `--R. jocqueiJD-S07
`--Griswoldia Dippenaar-Schoeman & Jocqué 1997R14, JD-S07 [Griswoldiinae]
|--G. acaenataR14
|--G. punctataR14
`--G. robustaR14

Amaurobioidea incertae sedis:
Chumma Jocqué 2001J01 [ChummidaeJD-S07]
|--*C. inquieta Jocqué 2001J01
`--C. gastroperforata Jocqué 2001J01
Phryganoporus candidusDo95
Midgee Davies 1995Da95
|--*M. binnaburra Davies 1995Da95
|--M. alta Davies 1995Da95
|--M. bellendenker Davies 1995Da95
|--M. littlei Davies 1995Da95
|--M. minuta Davies 1995Da95
|--M. monteithi Davies 1995Da95
|--M. parva Davies 1995Da95
|--M. pumila Davies 1995Da95
`--M. thompsoni Davies 1995Da95
ManjalaDa95
BakalaDa95
MalalaDa95
Insecutor [Insecutoridae]S93
|--I. aculeatus Petrunkevitch 1942S93
|--I. mandibulatus Petrunkevitch 1942S93
`--I. rufus Petrunkevitch 1942S93

*Type species of generic name indicated

References

[BS09] Blackledge, T. A., N. Scharff, J. A. Coddington, T. Szüts, J. W. Wenzel, C. Y. Hayashi & I. Agnarsson. 2009. Reconstructing web evolution and spider diversification in the molecular era. Proceedings of the National Academy of Sciences of the USA 106 (13): 5229–5234.

Coddington, J. A., & H. W. Levi. 1991. Systematics and evolution of spiders (Araneae). Annual Review of Ecology and Systematics 22: 565–592.

[CM07] Cokendolpher, J. C., & P. G. Mitov. 2007. Natural enemies. In: Pinto-da-Rocha, R., G. Machado & G. Giribet (eds) Harvestmen: The Biology of Opiliones pp. 339–373. Harvard University Press: Cambridge (Massachusetts).

Cuvier, G. 1831. The Animal Kingdom arranged in conformity with its organization, vol. 3. The Crustacea, Arachnides and Insecta, by P. A. Latreille, translated from the French with notes and additions, by H. M’Murtrie. G. & C. & H. Carvill: New York.

[Da95] Davies, V. T. 1995. A tiny litter spider (Araneae: Amaurobioidea) from Australian rainforests. Records of the Western Australian Museum Supplement 52: 119–129.

[Do95] Downes, M. F. 1995. Australasian social spiders: what is meant by ‘social’? Records of the Western Australian Museum Supplement 52: 25–32.

[FM11] Freire-Jr, G. de B., & P. C. Motta. 2011. Effects of experimental fire regimes on the abundance and diversity of cursorial arachnids of Brazilian savannah (cerrado biome). Journal of Arachnology 39 (2): 263–272.

[GC99] Griswold, C. E., J. A. Coddington, N. I. Platnick & R. R. Forster. 1999. Towards a phylogeny of entelegyne spiders (Araneae, Araneomorphae, Entelegynae). Journal of Arachnology 27: 53–63.

[J01] Jocqué, R. 2001. Chummidae, a new spider family (Arachnida, Araneae) from South Africa. Journal of Zoology 254: 481–493.

[JD-S07] Jocqué, R., & A. S. Dippenaar-Schoeman. 2007. Spider Families of the World. Royal Museum for Central Africa: Tervuren (Belgium).

[K92] Karsch, F. 1892. Arachniden von Ceylon und von Minikoy gesammelt von den Herren Doctoren P. und F. Sarasin. Berliner Entomologische Zeitschrift 36 (2): 267–310.

Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des Crustacés et des Insectes, vol. 3. F. Dufart: Paris.

[MC05] Machado, G., P. C. Carrera, A. M. Pomini & A. J. Marsaioli. 2005. Chemical defense in harvestmen (Arachnida, Opiliones): do benzoquinone secretions deter invertebrate and vertebrate predators? Journal of Chemical Ecology 31 (11): 2519–2539.

[PVD10] Paquin, P., C. J. Vink & N. Dupérré. 2010. Spiders of New Zealand: annotated family key and species list. Manaaki Whenua Press: Lincoln (New Zealand).

[R14] Ramírez, M. J. 2014. The morphology and phylogeny of dionychan spiders (Araneae: Araneomorphae). Bulletin of the American Museum of Natural History 390: 1–374.

[S93] Selden, P. A. 1993. Arthropoda (Aglaspidida, Pycnogonida and Chelicerata). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 297–320. Chapman & Hall: London.

[WZ08] Wang, X.-P., & M.-S. Zhu. 2008. Himalmartensus, a new genus of the spider family Amaurobiidae from Nepal (Araneae). Journal of Arachnology 36 (2): 241–250.

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