The families of British spiders

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L. Watson and M. J. Dallwitz

Character List

#1. <Synonyms:>/

~ (‘alternatively’) is here used to indicate ‘sometimes not unreasonably included in or reduced to’.

#2. <Common collective name of family members:>/

#3. <Habitat, aquatic or terrestrial:>/

1. terrestrial <land dwelling> /

2. moving across the surface of still water to take victims from it/

3. fully aquatic, living and hunting in slow-moving or still water, and maintaining a submerged, air-filled bell web as home base/

Morphology

#4. The adult spiders <length>/

mm long/

Lengths, recorded for adults, are measured from the front of the carapace (exclusive of appendages) to the posterior end of the abdomen.

#5. The adult females <whether green>/

1. bright green/

2. not bright green/

#6. The adult spiders <build, with reference to the abdomen>/

1. slender-bodied/

2. of medium build/

3. decidedly plump-bodied/

The males of a species generally have relatively longer legs and a narrower abdomen than the females.

#7. The adult spiders <length of legs relative to body length>/

1. decidedly short-legged <the longest pair no more than 1.5 times the body length>/

2. with legs of medium length <the longest pair more than 1.5 but less than 3 times the body length>/

3. decidedly long-legged <the longest pair at least three times but less than 5 times the body length>/

4. harvestman-like with very long, thin legs more than five times the body length/

#8. The adult spiders <whether crab-like in stance and locomotion>/

1. markedly crab-like in stance and locomotion/

2. not crab-like in stance and locomotion /

#9. The caput <whether exhibiting lobes, turrets or globular extensions>/

1. conspicuously lobed, turreted, or with globular swellings <some Linyphiidae>/

2. not conspicuously ornamented with lobes, turrets or globular swellings /

#10. The adult spiders <number of eyes>/

1. with six eyes/

2. with eight eyes/

The eyes of spiders (usually 8, sometimes 6) take the form of simple ocelli. Much classificatory interest and identificatory convenience attaches to their patterns of insertion, and to their relative sizes. For comparative descriptive purposes, they are classified (presumably according to supposed homologies, and with reference to 8-eyed forms) as follows:-

2 anterior medians (front middle: AME); 2 front anterior laterals (front outside: ALE); 2 posterior medians (back middle: PME); and 2 posterior laterals (back outside: PLE).

This terminology involves interpreting the various patterns as basically representing two horizonatal rows, anterior and posterior. The eye patterns of 6-eyed spiders (Dysderidae, Oonopidae, Scytotidae and Segestriidae) are not overtly interpretable in such terms; and while they are readily applicable to the eye layouts of most 8-eyed spiders, several 8-eyed families are characteristically anomalous (see the accompanying illustrations, which should be cross-referenced with the diagrams available via the ‘General morphology’ toolbar button).

#11. The eyes <when 8, pattern>/

1. in two <more or less curved> horizontal rows of 4/

2. in an oval cluster <alternatively interpretable as two rows of 4, the anterior row recurved and the posterior procurved>/

3. ostensibly in three rows of 4+2+2, the anterior row of four more or less recurved/

4. ostensibly in three rows of 4+2+2, the anterior row of 4 incorporating two enlarged medians, and facing forwards on the square-fronted caput like a battery of car headlamps, with the two rows behind each comprising a pair of small eyes borne dorsilaterally on the top of the caput <Salticidae>/

5. comprising two relatively large medians, with three small laterals in triangular arrangements on either side <the characteristic Atypus pattern>/

6. comprising a pair of large, circular anterior medians and three smaller laterals in a curved-longitudinal row on either side <the characteristic zodariid pattern>/

7. comprising four small ones at the extremities constituting a large quadrilateral, with the other four in a small, anterior-median, trapezoid arrangement whose anterior side is shorter and the inner pair of which are the largest of all <the Eresus pattern>/

8. in a distinctive hexagonal pattern <the Oxyopes pattern>/

#12. The eyes <when 6, pattern>/

1. clustered almost in a circle <this anteriorly open, or more or less closed>/

2. all large, closely aggregated anteriorly on the cephalothorax, with the median pair oval and contiguous, flanked by a pair on either side <the characteristic Oonops pattern>/

3. arranged as a pair of separate medians and two pairs of smaller laterals <the segestriid pattern>/

4. in pairs at the front of the cephalothorax, the two lateral pairs placed obliquely, and the median pair larger and situated transversely ahead of them <the characteristic scytotid pattern>/

#13. The eyes <colour>/

1. all clear and glassy/

2. all dark/

3. light, except for the dark anterior medians/

#14. The eyes <whether ringed with white hairs>/

1. conspicuously ringed with white hairs/

2. not ringed with white hairs/

#15. The chelicerae <plane of articulation>/

1. articulated to move upwards and downwards, lying parallel to the long axis of the body, and relatively massive <Atypidae>/

2. <large or small,> articulated to move horizontally inwards and outwards or obliquely /

Chelicerae (sing. chelicera): the jaws of the spider, representing the first pair of organs of the cephalothorax. Each comprises a large basal part and a fang. The latter, which represents a claw-like distal segment, bears near its tip the opening of the duct from the poison gland.

#16. The chelicerae <whether basally fused>/

1. fused at the base/

2. free at the base /

#17. The maxillae <length/breadth>/

1. longer than broad/

2. about as long as broad/

3. shorter than broad/

#18. The palpal organs of the male <pedipalps, form: see Notes>/

1. of complex structure and enclosed <at least partially> by the specialized, hollowed tarsal segment (the cymbium)/

2. comprising an exposed bulb attached to the little-modified tarsal segment (no cymbium)/

Palpi (palps, pedipalps): the second pair of appendages of the cephalothorax, located behind the chelicerae (q.v.) and in front of the first pair of legs. By comparison with the legs (q.v.), they exhibit coxa, femur, patella, tibia and tarsus, but lack the metatarsus. The coxae of the palps constitute the maxillae; i.e., the spider’s palps are homologous with the maxillary palps of insects. The palps of male spiders are modified - often greatly so - for sperm transfer.

The palpal organ of the male spider is attached to the terminal segment of the palp, which represents the tarsus. The latter is commonly broadened and hollowed to receive it, and is then termed the cymbium. The cymbium in some families bears a small branch, hook or knob, or a separate sclerite attached to it by a membrane, which is termed the paracymbium.

A male palp varies greatly in appearance, depending on the direction from which it is viewed (dorsal, ventral, inner side, or outer side). Except where stated otherwise, Blackwall's illustrations represent ventral (underside) views of left palps, and the palpal organs are depicted in their normal, unexpanded state. Males that have recently moulted are usually lighter and less sclerotized; and in sub-adults the palpal tarsi, though usually somewhat swollen, can be expected to lack the complex arrangements of sclerites characterizing the adults.

Mature male spiders are readily recognised by their pedipalps, which are complex in structure. In addition, the usually relatively small and slim male abdomen never exhibits an epigyne. Mature females have simple pedipalps (though rarely they are distally expanded), and the relatively large and plump abdomen usually exhibits an epigyne. Immature spiders inevitably pose problems for identification. They have modified palps and no epigyne, and are often pale (sometimes almost translucent) and of relatively fragile appearance.

#19. The male palps <pedipalps, presence of a paracymbium: see Notes>/

1. with a well developed paracymbium/

2. without a paracymbium /

#20. The female palps <with or without a claw: see Notes>/

1. with a claw/

2. without a claw /

#21. The adult spiders with the longest legs represented by <pairs I, II, III or IV>/

1. I/

2. II/

3. III/

4. IV/

#22. The front legs <constitution and carriage>/

1. short or shortish, and rather stout/

2. not short and stout/

#23. The first two pairs of legs <I and II, whether laterigrade and borne crab-like>/

1. laterigrade <the morphologically front side directed upwards, the stance and locomotion usually crab-like>/

2. not laterigrade, the stance and locomotion not crab-like /

#24. The first two pairs of legs <I and II, whether longer and stouter than the second pair>/

1. conspicuously longer and often stouter than the third and fourth pairs <the stance and sideways locomotion crab-like>/

2. not markedly longer and stouter than the third and fourth pairs <the stance and locomotion usually not crab-like>/

#25. The first two pairs of legs <distinctive spininess: Mimetidae>/

1. having the tibia and metatarsus armed with long spines, these forwardly-curved towards their tips and increasing in length acropetally along the row, between which are single rows of shorter curved spines/

2. without the spines characteristic of Mimetidae /

#26. The trochanters <notching>/

1. not notched/

2. of only the IVth legs notched/

3. of all the legs notched/

#27. Metatarsus IV <whether concave above>/

1. concave above/

2. not concave above/

#28. Metatarsus IV of the females <presence of a calamistrum: see Notes>/

1. with a dorsal series of curved bristles (the calamistrum, which is reduced in the males)/

2. without a calamistrum/

Calamistrum: a longitudinal series of curved bristles, on the dorsal edge of the metatarsus of the fourth leg in some families. It is used to comb out a viscid secretion extruded by the cribellum (q.v.), which combines with the ordinary threads to form an adhesive, faintly bluish, hackled (lace-like) web.

Mature male spiders are readily recognised by their pedipalps, which are complex in structure. In addition, the usually relatively small and slim male abdomen never exhibits an epigyne. Mature females have simple pedipalps (though rarely they are distally expanded), and the relatively large and plump abdomen usually exhibits an epigyne. Immature spiders inevitably pose problems for identification. They have modified palps and no epigyne, and are often pale (sometimes almost translucent) and of relatively fragile appearance.

#29. The <calamistrum> bristles <in one or two rows>/

1. in a single row/

2. in two rows/

#30. Scopulae <brushes of close-set hairs, presence>/

1. present on <at least> tarsi I and II/

2. absent/

#31. Tarsal claws <number>/

1. 2/

2. 3/

#32. The tarsi <whether with claw tufts: recorded only for 2-clawed tarsi>/

1. with claw tufts/

2. without claw tufts/

#33. Tarsus IV <presence of a ventral ‘comb’>/

1. with a ventral row of serrated bristles constituting a ‘comb’/

2. without a ventral ‘comb’/

#34. The abdomen <whether angular>/

1. smoothly rounded /

2. angular in shape/

#35. The abdomen <patterning>/

1. conspicuously patterned dorsally/

2. plain dorsally/

#36. The abdomen <Anyphaenidae pattern>/

1. conspicuously exhibiting a pair of characteristic, medio-longitudinal irregular dark markings (see illustrations) <Anyphaenidae>/

2. not marked as in Anyphaenidae /

#37. The abdomen <whether partly red>/

1. predominantly bright red, with black markings/

2. predominantly bright red and yellow/

3. exhibiting red or pink colour, but neither predominantly bright red and black nor predominantly bright red and yellow/

4. without any red coloration /

#38. The abdomen <whether partly green>/

1. entirely or partly green/

2. without green coloration /

#39. The abdomen <tracheal spiracles>/

1. exhibiting a pair of large tracheal spiracles behind the book lungs/

2. with a single, inconspicuous tracheal spiracle/

#40. The epigastric furrow <straight or pro-curved>/

1. nearly straight/

2. pro-curved <curved forwards> between the lung slits/

#41. The tracheal spiracles <and slit, position>/

1. more or less equidistant from the epigastric furrow and the spinnerets/

2. behind the epigastric fold/

3. close to the spinnerets/

#42. The spinnerets <arrangement>/

1. in a more or less transverse row/

2. clustered and superposed <not in a transverse row>/

#43. The anterior spinnerets <insertion>/

1. wide apart/

2. close together/

#44. <Segmentation of the spinnerets:>/

1. the spinnerets all unsegmented /

2. the posterior spinnerets 3-segmented/

3. with one pair of spinnerets <the posterior, or outer ones> 2-segmented/

#45. The abdomen of the females <presence of a cribellum: see Notes>/

1. furnished with a plate-like cribellum <spinning organ> anterior to the spinnerets (this being reduced in the males)/

2. without a cribellum/

Cribellum: a spinning organ, in the form of a transverse plate, found immediately in front of the spinnerets in some families. It is covered with minute spigots, secreting a viscid substance which, combined with the normal threads by use of the calamistrum (q.v.), forms adhesive, faintly bluish, hackled (lace-like) web.

Mature male spiders are readily recognised by their pedipalps, which are complex in structure. In addition, the usually relatively small and slim male abdomen never exhibits an epigyne. Mature females have simple pedipalps (though rarely they are distally expanded), and the relatively large and plump abdomen usually exhibits an epigyne. Immature spiders inevitably pose problems for identification. They have modified palps and no epigyne, and are often pale (sometimes almost translucent) and of relatively fragile appearance.

#46. The reproductive openings of the females <presence of an epigyne: see Notes>/

1. associated with an epigyne/

2. without an epigyne/

Epigyne (epigynum): a sclerotised plate, borne by most adult female spiders on the underside of the abdomen in front of the epigastric fold. It forms part of the reproductive apparatus, and variation in its complexity is of taxonomic interest.

Mature male spiders are readily recognised by their pedipalps, which are complex in structure. In addition, the usually relatively small and slim male abdomen never exhibits an epigyne. Mature females have simple pedipalps (though rarely they are distally expanded), and the relatively large and plump abdomen usually exhibits an epigyne. Immature spiders inevitably pose problems for identification. They have modified palps and no epigyne, and are often pale (sometimes almost translucent) and of relatively fragile appearance.

#47. The adults <whether constructing a silken retreat>/

1. constructing a terrestrial retreat in the form of a silk tube/

2. constructing a retreat in the form of an underwater diving-bell, which is kept filled with air/

3. constructing neither a terrestrial silken retreat nor an underwater diving-bell /

#48. The adults <whether forming snare-webs>/

1. making snare-webs/

2. not making snare-webs/

#49. The adults <snare-web makers, form of the web>/

1. constructing orb webs <or partial orbs>/

2. constructing tangled webs/

3. constructing horizontal sheet webs <cobwebs>/

4. constructing funnel-shaped or tubular webs/

#50. The adults <not snare-web making, behaviour>/

1. lying in wait for their prey/

2. actively pursuing their prey/

#51. The females <whether carrying egg sacs: see Notes>/

1. carrying egg sacs attached to their spinnerets/

2. carrying egg sacs via their chelicerae and palps/

3. not carrying egg sacs /

British representation

#54. <Distribution of British representatives:>/

1. confined to southern England/

2. widespread /

Comments

#55. <General comments:>/

#56. Abbreviated taxon name:/

#57. <Illustrations:>/


To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. The families of British spiders. Version: 4th January 2012. http://delta-intkey.com’.

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