1. Abdomen RED or marked with RED 2
- Abdomen BLACK, marked with WHITE or covered, above, with SILVERY hairs.... 16
- Abdomen BROWN, GRAY, YELLOW or spotted ................ 19
2. Cephalothorax RED above (cardinalis, Whitmanii, ardens, McCookii) ..... 3
- Cephalothorax black with inconspicuous BLACK, BROWN or GRAY HAIRS (clarus,
coloradensis, insolens, californicus, Johnsonii, ardens, formosus, brunneus) ... 6
- Cephalothorax BLACK and WHITE (Tyrrellii, insignarius) ..... 14
- Cephalothorax RED and WHITE (coccineus, femoratus) ..... 15
3. Abdomen RED, WITHOUT black BANDS ...................... 4
- Abdomen RED WITH two black BANDS ........ McCookii (in part)
4. Cephalothorax ALL RED above; abdomen WITHOUT white spots; fringe on first
leg BROWN or BLACK and WHITE; no white band on palpus .. 5
- Cephalothorax with bare BLACK region over front eyes: abdomen sometimes having
a pair of WHITE SPOTS at end; fringe on first leg ALL WHITE; palpus with WHITE
BAND above. A northern species ............... Whitmanii
5. First leg fringed with BLACK AND WHITE; abdomen without basal band. A southern
and western species .... cardinalis
-First leg fringed with BROWN; abdomen with indistinct LIGHT basal band .. McCookii (in part)
6. Abdomen RED, or red BANDED WITH BLACK ................ 7
- Abdomen BLACK SPOTTED with RED ........... insolens (in part)
7. Abdomen banded with BLACK ............................ 8
- Abdomen UNIFORM RED .................................. 11
8. Abdomen with one BLACK BAND; outer corner of maxilla with hooked apophysis ..... 10
- Abdomen with TWO BLACK BANDS ........................ 9
9. Palpus all BLACK; outer corner of maxilla with hooked apophysis .............. ardens (in part)
- Palpus WHITE above; outer corner of maxilla with short point ........................ californicus
10. First leg longer than second by only tarsus and metatarsus; fringe on first
leg not very heavy .......... clarus
- First leg longer than second by tarsus, metatarsus and part of tibia; fringe
on first leg heavy and conspicuous coloradensis
11. Palpus with WHITE hairs above .......................... 12
- Palpus WITHOUT white hairs above ...................... 13
12. Distal end of femur of first leg with bunch of WHITE HAIRS below ............ insolens (in part) and
brunneus
(If found in the north the spider is, almost certainly, brunneus, if in the south, insolens. These two
species may be distinguished from each other by the palpi).
- no DISTINCT BUNCH of white hairs below femur of first I leg ...... Johnsonii
13. Cephalothorax with BROWNISH HAIRS over a black ground; abdomen with scattered
WHITE HAIRS, especially behind; no white hairs above femur of first leg .......... ardens (in part)
- Cephalothorax with BLACK HAIRS over a black ground; abdomen with scattered
BLACK HAIRS; femur of first leg with WHITE HAIRS above ........................... formosus
14. Abdomen RED marked with BLACK and WHITE; first leg fringed with white insignarius
- Abdomen RED marked with WHITE only; first leg fringed with BLACK AND WHITE .. Tyrrellii
15. Cephalothorax with WHITE BAND over front eyes and white side bands beginning
at lateral eyes of first row; palpus with WHITE BAND on femur only; falces dark,
with streaks of white hairs; femur of first leg with iridescent plate beneath .........................femoratus
- Cephalothorax with NO WHITE BAND over front eyes and with white side bands running back
from dorsal eyes; palpus with white band throughout length; falces bare, blue; no plate under femur of first leg.. coccineus
16. Cephalothorax DARK with a WHITE SPOT between dorsal eyes, a white bar on each side
of head between eyes of second and third rows, and ridges of rusty hairs on cephalic plate. Femur
of first leg with crest of hairs above and enlarged plate below ...... Putnamii (in part)
- Whole body BLACK, upper surface of cephalothorax and abdomen covered with SILVERY HAIRS opifex
- Cephalothorax black sometimes banded with white; abdomen BLACK with TRIPUNCTATE WHITE markings .. 17
17. Cephalothorax banded with WHITE ....................... 18
- Cephalothorax ALL BLACK ................................ audax
18. Cephalothorax with wide white bands beginning at dorsal eyes and covering posterior sides ............... variegatus
- Cephalothorax with transverse scalloped white band behind dorsal eyes, on thorax ......... Howardii
19. Sides of head enlarged to form TUBERCLES; first leg heavily fringed with YELLOW HAIRS and ornamented,
on upper side of femur, by a long PENCIL OF STIFF DARK HAIRS ......................................... arizonensis
- No tubercles nor yellow fringes ........................ 20
20. Small YELLOW spiders (6-7 mm.) with two dark bands dotted with white on
abdomen (this species looks like faded specimens of McCookii but the palpus
has the tube longer and narrower and there is no rugose part at the end of the bulb) ....... pius
- Body NOT YELLOW ........................................ 21
21. Fringe on first leg ALL BROWN, found on upper side of femur and below femur
patella and tibia .......... octopunctatus
- Fringe on first leg NOT ALL brown ........................ 22
22. Cephalic plate with ridges of RUSTY RED hairs ............ 23
- Cephalic plate without ridges of hairs ................... 24
23. Cephalothorax DARK SPOTTED WITH WHITE; falces with long white hairs covering
front faces; femur of first leg with crest of hairs above and enlarged plate
below ..... Putnamii (in part)
- Cephalothorax with uniform covering of WHITE HAIRS; falces with white hairs
cut squarely off halfway down; femur of first leg with a bunch of hairs at distal
end above and a heavy fringe below .............. carolinensis
24. Cephalothorax with uniform covering of GRAY HAIRS ...... purpuratus
- Cephalothorax dark with wide white bands on sides .... otiosus