Table 1. Major spider lineages referenced throughout the text.

Superscripts (column 1) reference node labels in Fig. 1 (summary of family level relationships).

Lineage	Composition and placement	Description/characteristics
1 Araneae	All spiders	Cosmopolitan; cheliceral venom glands, ability to produce silk from abdominal silk glands; male pedipalps modified for sperm transfer
2 Mesothelae	Plesiomorphic sister group to all living spiders	SE Asia; mid ventrally positioned spinnerets; distinct dorsal abdominal tergites, very narrow sternum
3 Opisthothelae	The two major spider lineages	Typical terminal spinneret placement and sternal morphology
4 Mygalomorphae	Trapdoor, baboon and funnel spiders, tarantulas, and their kin	Paraxial chelicerae with venom glands; most lead sedentary lives in burrows; lack anterior median spinnerets; often large and hirsute; two pairs of book lungs
5 Atypoidina	Sister group to remaining mygalomorphs	Most species with vestigial abdominal tergites and unique modifications to male pedipalp
6 Avicularoidea	All remaining mygalomorph taxa	Includes major mygalomorph families, nearly half of which are likely not monophyletic
7 Theraphosoidina	Comprises families Theraphosidae and Barychelidae	Includes the typically large and hirsute tarantulas and baboon spiders
8 Araneomorphae	Over 90% of all spider diversity	Anterior median spinnerets fused to form a cribellum (later lost multiple times)
9 Paleocribellatae	Comprises single family Hypochilidae; hypothesized sister group to all other araneomorphs	Hypochilid synapomorphies, e.g., cheliceral depression; also retain a number of primitive traits including two pairs of booklungs
Neocribellatae	Remaining spider lineages	Paracribellum (complimentary spinning field to cribellum); extension of venom gland into prosoma
Austrochiloidea	Families Austrochilidae and Gradungulidae; sister group to all other neocribellate lineages	Gondwanan taxa with notched tarsal organs; typically with two pairs of booklungs–posterior pair modified as tracheae in some taxa
10 Haplogynae	Neocribellate lineage with simple genitalia; includes spitting spiders and cellar spiders	Spinnerets lack tartipores; mating with palps inserted simultaneously; in some taxa female genital opening lacks an epigynum; chelicerae fused at base, synspermia, male palpal organ simple
11 Entelegynae	Comprises all remaining spider lineages with complex genitalia	Female genitalia with a flow through system of separate copulatory and fertilization ducts; male palpal organ typically under hydraulic control
Palpimanoidea	Comprises a number of enigmatic families	Araneophages with lateral scopulae on anterior legs
Eresoidea	Includes 3 families: Eresidae, Hersiliidae, Oecobiidae; sister to remaining entelegynes	Controversial superfamily; oecobiids and hersiliids share a unique attack behavior
Orbiculariae	Comprises the Deinopoidea and Araneoidea	Members of this lineage include cribellate and ecribellate orb-web weavers as well as derived araneoids that use adhesive threads to construct sheet and cob-webs
Deinopoidea	Includes the cribellate orbicularian families Uloboridae and Deinopidae	Construct cribellate orb web; long considered sister group to adhesive orb web weavers on basis of behavioral web construction data
12 Araneoidea	Spider superfamily that includes adhesive orb web weaving taxa and others	Members of this lineage all use adhesive threads; monophyly supported by a number of spinning and other morphological characteristics
13 RTA	Large diverse lineage of spiders that includes wolf, jumping, running, fishing, and crab spiders	Defined primarily by the presence of a projection on the male palp–the retrolateral tibial apophysis (RTA)
14 Dionycha	Subclade of the RTA lineage, comprises about 1/3 of all spider diversity	Defined as a group based on their two clawed condition with flanking tufts of setae for adhesion to smooth surfaces
Lycosoidea	Large superfamily comprising 10 families including fishing and wolf spiders	Monophyly of this superfamily is based on a number of morphological features (not universal) including a grate-shaped tapetum, an oval-shaped calamistrum, and male palpal features