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Guide to spider Morphology
Galleries of spiders
(click here to know more about spider Morphology)
(click here to see images of spiders)

A Key To Spider Families

1a Eight eyes present
(sometimes small eyes are very difficult to see)
1b Six eyes present


2a Cribellum (a small plate just in front of spinnerets) absent 3  
2b Cribellum (a small plate just in front of spinnerets) present 24
3a Chelicerae directed downward or downward and forward, cheliceral fangs directed towards each other  4  
3b Chelicerae projecting forward, cheliceral fangs directed more or less parallel to the main body axis

fam. Atypidae

4a Tarsi with three claws 5  
4b Tarsi with two claws 17  
5a Spiders with extremely long and thin legs, leg II 4-5 times longer than body

fam. Pholcidae


  <= Click to enlarge

5b Spiders without extremely long and thin legs 6  
6a Tibia and metatarsus I & II with a row of long prolateral spines

fam. Mimetidae

6b Tibia and metatarsus I & II without a row of long prolateral spines 7  
7a Tarsi IV with 6 or 10 serrated setae, forming a comb

fam. Theridiidae

7b Tarsi IV without such a comb 8  
8a Eye group in hexagonal arrangement

fam. Oxyopidae

8b Eye group not in hexagonal arrangement 9  
9a Tarsi with numerous trichobothria  (extrimly thin sensory setae) 10  
9b Tarsi without trichobothria 13  
10a Tarsal trichobothria in a single dorsal row 11
10b Tarsal trichobothria irregular, in two dorsal rows 12

11a The six spinnerets in a more or less transverse row

fam. Hahniidae

11b The six spinnerets in three rows

fam. Agelenidae

12a Posterior row of eyes so strongly recurved that it may be considered to form two rows



Posterior row of eyes slightly recurved and not forming two distinct rows

fam. Pisauridae


  Face of Pisaura Face of Dolomedes (click photo)
13a Chelicerae divergent from base, usually long and strong

fam. Tetragnathidae

   Click picture
13b Chelicerae not divergent from base 14  
14a Femur I distinctly thicker than femur IV (~ 3 times), small spiders with spherical abdomen 

fam. Theridiosomatidae

14b Femur I & IV almost the same thickness 15  
15a Tibia IV with 1 or 2 dorsal spines 

fam. Linyphiidae

15b Tibia IV usually with numerous spines and/or setae 16  
16a Spinnerets situated anteriorly almost in the center of ventral surface of abdomen.

fam. Araneidae,
genus Micrathena

16b Spinnerets situated at the end of abdomen

fam. Araneidae

17a Tracheal spiracle in middle of ventral surface of abdomen, or closer to the epigastric furrow 

fam. Anyphaenidae

17b Tracheal spiracle just in front of the spinnerets 18  
18a Eyes arranged in three rows, the front or anterior median eyes very large 

fam. Salticidae

18b Eyes arranged in two rows, the front or anterior median eyes not especially large 19  
19a Colulus present. Legs I & II much longer than III & IV, spiders crab-shaped.


  <= Click to see photo
19b Colulus absent 20  
20a Tarsi I & II with scopulae (thick dense setae)

fam. Philodromidae

20b Tarsi I & II without scopulae 21  
21a Anterior spinnerets cylindrical, widely separated at base 

fam. Gnaphosidae

21b Anterior spinnerets conical, separated by a distance much closer than their diameter 22  
22a Clypeus less than the diameter of an anterior median eye (AME), if it is about so (Fig) - posterior median eyes (PME) separated  about their diameter 

fam. Clubionidae

Clypeus - distance between edge of carapace and anterior row of eyes.
22b Clypeus not less than the diameter of an anterior median eye (AME), usually at least 2-3 times as wide 23  
23a Anterior lateral eyes (ALE) not larger than AME 

fam. Corinnidae


Anterior lateral eyes (ALE) larger than AME

fam. Liocranidae

24a All eyes homogenous, light in color, tarsi with a dorsal row of trichobothria 

fam. Amaurobiidae

24b Eyes homogenous, dark in color, or heterogeneous light and dark in color; tarsi without trichobothria 25  
25a Eyes homogenous, dark; metatarsus IV compressed and concave above

fam. Uloboridae

25b Eyes heterogeneous; metatarsus IV normal shape (not compressed and concave above)

fam. Dictynidae


Spiders with extremely long and thin legs, II leg 4-5 times longer than body

fam. Pholcidae

26b Spiders without extremely long and thin legs 27  

Chelicerae large directed downward and forward, carapace and legs deep red

fam. Dysderidae


Chelicerae projecting downward, carapace and legs not red



28a Carapace strongly arched behind, body dappled

fam. Scytodidae

28b Carapace not arched behind, body not dappled

fam. Segestriidae






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© American Museum of Natural History,  June 01, 2002
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