The Salticidae (Spiders) of Panama/Zygoballus

by Arthur M. Chickering

Genus Zygoballus Peckham, 1885

The Peckhams had a single female from Panama for which they made the genus Messua. Simon transferred the genus to Zygoballus. Professor Petrunkevitch had two females upon which he based the description of Z. maculatipes. Mr. Banks identified a female as Z. rufipes Peckham, but I believe this specimen to belong to Z. optatus sp. nov. Mr. Banks also identified an immature female as Z. tibialis F. Cambridge. This specimen is impossible to place with certainty but it probably belongs to one of the new species described in this paper. I conclude, therefore, that at the present time four species of Zygoballus are known from Panama, two of them only from females.

Key to the species of Zygoballus from Panama

Males

1. Palpal tibial apophysis slender, fully half as long as bulb; embolus long and slender, fully half as long as bulb. . . . . Z. optatus, (p. 410)
2. Palpal tibial apophysis short and robust, about one third as long as bulb; embolus about one third as long as bulb. . . . . Z. electus, (p. 405)

No workable key has yet been devised for use with the four kinds of females now referred to this genus.

Zygoballus desidiosus (Peckham), 1896

Messua desidiosa Peckham, 1896
M. desidiosa F. Cambridge, 1901
Z. desidiosus Simon, 1903
M. desidiosa Banks, 1909
Z. desidiosus Petrunkevitch, 1911
Z. desidiosus Petrunkevitch, 1925

I am very doubtful of the correctness of the assignment of the species to the genus Zygoballus. The type should be carefully studied in accord with modern methods. Apparently the species has not yet appeared in my collection. The type female was sent to the Peckhams by Count Keyserling.

Zygoballus electus spec. nov.
Figures 363–367

Male holotype. Total length 2.24 mm. Carapace 1.26 mm. long, 1.02 mm. wide at level of PLE which occupy full width of carapace, .77 mm. tall and, therefore, about .75 as tall as wide; dorsal surface nearly flat back to steep posterior declivity which begins a little more than one third of the distance from PLE to posterior border and is typically abrupt for the genus; with a median longitudinal thoracic groove of moderate length beginning opposite posterior borders of PLE.

Eyes. Seen from in front, anterior row recurved so that a line tangent to dorsal borders of ALE cuts off about one twelfth of the diameter of AME. Posterior row wider than anterior row in ratio of 24 : 23, wider than middle row in ratio of 24 : 21. Quadrangle of laterals wider than long in ratio of 48 : 35. Total eye space occupies about forty fifty-sevenths of the length of the carapace. Ratio of eyes AME : ALE : PME : PLE = 15.5 : 8:5 : 1.75 : 7.5. AME contiguous to one another and to ALE. Middle eyes closer to ALE than to PLE in ratio of 11 : 9. Height of clypeus equal to about one fourth of the diameter of AME. Clypeus decorated with a rich coat of white lanceolate hair showing considerable iridescence, one long white bristle beneath outer border of AME, and probably three long, upturned, light colored bristles in lower angle between AME.

External Anatomy of Spiders

Fig. 360. Orvilleus crassus Chickering; first leg, prolateral view.
Figs. 361–362. O. crassus Chickering; male palp, ventral view; and palpal tibia, retrolateral view.
Figs. 363–364. Zygoballus electus Chickering; male chelicera, two views.
Figs. 365–366. Z. electus Chickering; male palp, ventral view; and palpal tibia, retrolateral view.
Fig. 367. Z. electus Chickering; epigynum, ventral view.
Figs. 368–369. Z. optatus Chickering; chelicera of holotype and of a paratype.
Figs. 370–371. Z. optatus Chickering; male palp, ventral view; and palpal tibia, retrolateral view.

Chelicerae. Only slightly porrect, considerably divergent; with several white lanceolate hairs on basal half in front; with a fairly robust tooth in front about three fifths from base; basal segment .38 mm. long; no basal boss observed. Fang of moderate size and length; moderately sinuous; with a definite small tooth on inner margin about one fourth from tip. Fang groove distinct, moderately excavated in middle; promargin with two teeth near medial end of groove, a very small tooth and a much larger one, both arising from a common base; retromargin with the remains of the fissidentate tooth much reduced, with the "hammer-headed" process only moderately developed (Figs. 363-364, taken from paratypes to avoid serious injury to the holotype).

Maxillae. Slightly convergent; longer than wide in ratio of about 2 : 1; only moderately notched in middle of outer border; with well developed scopula along truncature; outer distal corner well rounded, but with a very minute tubercle (not visible unless maxilla is removed for examination).

Lip. Wider than long in ratio of 6 : 5; basal excavations very short, obscure; reaches to about the middle of maxillae. Sternal suture straight.

Sternum. Scutiform, quite convex; longer than wide in ratio of 23 : 20; anterior border as wide as base of lip; first coxae separated by thirteen twentieths of the width of the sternum; widest between second coxae; posterior end bluntly rounded, not extended between fourth coxae which are separated by three tenths of their width.

Legs. 1423. Tibial index of first leg 16, of fourth leg 13.

	Femora	Patellae	Tibiae	Metatarsi	Tarsi	Totals
(measurements in mm)
1.	.83	.51	.56	.38	.32	2.60
2.	.54	.32	.38	.30	.29	1.83
3.	.51	.30	.32	.32	.29	1.74
4.	.80	.35	.58	.38	.29	2.40
Palp	.48	.17	.11	—	.38	1.14

All legs with a moderate supply of hair but no fringes or tufts.

Spines. First leg: femur only dorsal 0-1-1-1; patella 0; tibia only ventral 2-2-2; metatarsus only ventral 2-2. Second leg: femur only dorsal 0-0-1-1; patella and metatarsus as in first; tibia only prolateral 0-1, ventral 0-1r-0. Third leg: metatarsus 0-1 prolateral; elsewhere 0. Fourth leg: femur dorsal 0-1-1-0; patella and tibia 0; metatarsus as in third. Palpal spines: apparently only femur dorsal 0-0-1.

Palp. Femur only slightly bent ventrally; both patella and tibia short with latter about two thirds as long as former; tibial retrolateral apophysis a short stout spur turned inward at tip; embolus a slightly curved slender spine at tip of bulb (Figs. 365-366).

Abdomen. Almost a perfect oval in outline; longer than wide in ratio of 19 : 15; with a moderately well developed dorsal shield covering nearly entire dorsum; anal tubercle an inconspicuous yellowish white cone; six spinnerets small and closely crowded, anterior pair stoutest; position of colulus uncertainly indicated; tracheal spiracle near base of spinnerets with lip but no tubercle.

Color in alcohol. Carapace: almost uniformly reddish brown; eyes on black spots; white hairs on clypeus continued beneath ALE and PLE to posterolateral corners and part way down posterior declivity as a somewhat indefinite stripe on each side. Sternum and mouth parts different shades of reddish brown and brown. Legs: first pair entirely reddish brown except the yellowish tarsi; second and third pairs yellowish white with brownish ventral spots near distal ends of femora and brownish spots at intersections of patellae, tibiae, metatarsi, and tarsi; fourth pair yellowish white with brownish ventral spots near distal ends of femora and brownish spots at intersection of patellae, tibiae, metatarsi, and tarsi; fourth pair yellowish white with brownish prolateral spots on coxae, distal two thirds of femora reddish brown and brownish spots at intersections of patellae, tibiae, metatarsi, and tarsi. Abdomen: dorsal shield reddish brown overlying a series of brownish and yellowish chevrons in posterior two thirds; dorsolaterally on each side is a discontinuous white stripe from base to about the middle, then a white spot half-way to spinnerets; lateral sides brownish with narrow alternate brownish and yellowish stripes; venter with a broad brownish stripe from genital groove to base of spinnerets.

Female allotype. Total length 3.07 mm. Carapace 1.28 mm. long, 1.09 mm. wide at level of PLE, .70 mm. tall and, therefore, 0.64 as tall as wide; other features essentially as in male.

Eyes. Seen from in front, anterior row recurved so that a line tangent to dorsal borders of ALE cuts off about one tenth of the diameter of AME. Posterior row wider than anterior row in ratio of about 25 : 23, wider than middle row in ratio of about 25 : 21. Quadrangle of laterals wider than long in ratio of 10 : 7. Total eye space occupies two thirds of the length of the carapace. Ratio of eyes AME : ALE : PME : PLE = 15 : 8 : 2 : 8. AME barely separated from one another and from ALE. Middle eyes closer to ALE than to PLE in ratio of about 11 : 10. Height of clypeus equal to about two fifteenths of the diameter of AME. Clypeus decorated as in male.

Chelicerae. Vertical, parallel, of moderate size; basal segment .30 mm. long, excavated along medial border so that a small oval opening exists between the two. Fang moderately robust, evenly curved. Fang groove distinct; promargin with two teeth as usual; retromargin with an obscurely fissidentate tooth, visible as such only from certain angles.

Maxillae. Parallel, probably without minute tubercle at outer distal corner; otherwise as in male.

Lip. Slightly longer than wide. Otherwise essentially as in male.

Sternum. Longer than wide in ratio of 4 : 3. Otherwise essentially as in male.

Legs. 4123. Tibial index of first leg 21, of fourth leg 15.

	Femora	Patellae	Tibiae	Metatarsi	Tarsi	Totals
(measurements in mm)
1.	.71	.37	.51	.37	.31	2.27
2.	.58	.28	.32	.30	.26	1.74
3.	.57	.28	.34	.32	.30	1.71
4.	.90	.36	.51	.45	.32	2.54

Spines. First leg: tibia only ventral 2-2-2; metatarsus only ventral 2-2; elsewhere 0, tibial and metatarsal spines robust, long. Second leg: tibia ventral 0-1r-0; metatarsus ventral 2-2; elsewhere 0. Third leg: none observed. Fourth leg: metatarsus prolateral and retrolateral 0-1; elsewhere 0. No palpal spines.

Abdomen. Broadly ovoid, longer than wide in ratio of 14 : 11, widest a little behind the middle; other features essentially as in male.

Epigynum. Of moderate size; epigynal plate wider than long; with a very shallow posterior marginal notch having a broad rim; two strongly chitinized depressions nearly twice the width of one of them apart (Fig. 367).

Color in alcohol. Carapace: generally reddish brown, somewhat lighter than in male; eyes on black spots; white lanceolate hairs scattered over surface except for triangular area overlapped by abdomen which is smooth and devoid of hair; with no definite stripes. Palps yellowish white. Chelicerae light reddish brown; lips and maxillae nearly the same with whitish tips. Sternum brown. Legs: first pair generally reddish brown with tarsi and middle of metatarsi yellowish white and numerous short white lanceolate hairs on dorsal surfaces especially of tibiae and patellae; second and third pairs yellowish white with distal two thirds of femora dark brown except dorsal surfaces and dark brown distal ends of patellae, tibiae, and metatarsi; fourth pair with femora reddish brown except a narrow dorsal stripe, both ends of patellae reddish brown and also distal ends of tibiae and metatarsi. Abdomen: an indefinite central dorsal brownish stripe to beyond middle, then a large central dorsal spot anterior to anal tubercle; dorsolaterally a series of three poorly defined irregular reddish brown spots; laterally a series of narrow irregular oblique brownish stripes; venter with a broad brownish central stripe lighter through the middle and bounded on each side by a row of yellowish dots.

Type locality: Male holotype from Canal Zone Biological Area, Aug., 1936; female allotype from Porto Bello, R. P., Aug., 1936; several paratypes of both sexes from the Canal Zone Biological Area, June, 1936 and July 1939; El Valle, R. P., July, 1936; Porto Bello, R. P., Aug., 1936.

Zygoballus maculatipes Petrunkevitch, 1925

Only known from two females, one from Soná and the other from the San Lorenzo River region of Panama. The species has not appeared in my collection thus far.

Zygoballus optatus spec. nov.
Figures 368–372

As already pointed out, this species is the one identified by Mr. Banks as Z. rupifes Peckham.

Male holotype. Total length 2.60 mm. Carapace 1.38 mm. long, 1.09 mm. wide at level of PLE which occupy the full width of the carapace, .83 mm. tall and, therefore, about .76 as tall as wide; thoracic part gently arched from AME to just behind PLE from which place the steep declivity continues to posterior border in the typical manner for the genus; at the top the steep declivity only slightly concave; no median thoracic groove observed.

Eyes. Seen from in front, anterior row recurved so that a line tangent to dorsal borders of ALE cuts off about one fifteenth of the diameter of AME. Posterior row wider than anterior row in ratio of about 10 : 9, wider than middle row in ratio of about 17 : 14. Quadrangle of laterals wider than long in ratio of 25 : 18. Total eye space occupies twenty thirty-firsts of the length of the carapace. Ratio of eyes AME : ALE : PME : PLE = 15 : 8 : 2 : 7. AME nearly contiguous to one another and definitely so to ALE. Middle eyes closer to ALE than to PLE in ratio of about 4 : 3. Height of clypeus equal to one sixth of the diameter of AME. Clypeus decorated only with a weak ventral fringe of light colored bristles, one long brownish bristle beneath outer border of each AME, a few inconspicuous loose white lanceolate hairs, and three brownish upturned bristles in lower angle between AME.

Chelicerae. Moderately porrect, divergent, and produced; basal segment .47 mm. long; a fairly robust hook on basal segment in front near distal end; with no basal boss. Fang of moderate size, rather robust in basal three fifths, then slenderer and evenly curved to tip. Fang groove distinct, considerably excavated; with two promarginal teeth, a small medial one and a robust one a short distance toward base of fang; retromargin with a small, somewhat fissidentate tooth nearly opposite the smaller of the two promarginal teeth, and a large process with ridges extending over much of the posterior surface of the basal segment a little closer to base of fang than to fissidentate tooth (a considerable degree of variation has been noted in both fissidentate tooth and the "hammer-headed" process among paratypes); these conditions shown in holotype (Fig. 368) and in a paratype (Fig. 369).

Maxillae. Parallel; longer than wide in middle in ratio of about 9 : 5; only moderately concave in middle of outer border; outer distal corner well rounded and without a tubercle or hook; scopula moderately developed along truncature.

Lip. Wider than long in ratio of 11 : 9; transversely grooved at base; well rounded distally. Sternal suture straight.

Sternum. Scutiform, quite convex; longer than wide in ratio of 13 : 10; widest between second coxae; anterior border slightly narrower than base of lip; anterior coxae wider apart than base of lip; posterior end a sharp point not extended between fourth coxae which are separated by one sixth of their width.

Legs. 1423. Tibial index of first leg 13, of fourth leg 12.

	Femora	Patellae	Tibiae	Metatarsi	Tarsi	Totals
(measurements in mm)
1.	.96	.47	.77	.59	.35	3.14
2.	.64	.35	.44	.45	.31	2.19
3.	.64	.30	.37	.41	.32	2.04
4.	1.02	.45	.64	.54	.38	3.03
Palp	.46	.22	.12	—	.40	1.20

First coxae and femora moderately enlarged. All legs with a moderate supply of hair but without fringes or tufts.

Spines. First leg: femur dorsal 0-1-1-1, prolateral only distal 1; patella only prolateral 0-1-0; tibia only ventral 2-2-2, the first promarginal about one fourth from base, not well matched in pairs; metatarsus only ventral 2-2. Second leg: femur only dorsal 0-1-1-1; patella 0; tibia only ventral 0-1r-0; metatarsus as in first. Third leg: femur only dorsal distal 1; patella and tibia 0; metatarsus only retrolateral 0-1. Fourth leg: femur dorsal 0-1-1-1; patella 0; tibia only ventral 0-0-2; metatarsus prolateral 0-1, retrolateral 0-1, ventral 0-2. Palpal spines: apparently only femur dorsal distal 1.

Palp. Femur moderately bent ventrally; patella and tibia both short, with latter only a little more than half as long as former; tibial apophysis a long slender spine, gently sinuous, reaching almost to division of bulb; bulb only moderately swollen, does not overlap tibia, divided into a white anterior smaller lobule and a larger reddish brown posterior lobule; embolus arises near anterior end as a long slender filament (Figs. 370–371).

Abdomen. Rather small; ovoid, longer than wide in ratio of 11 : 7, widest near middle; with a moderately well developed dorsal shield covering practically entire dorsum; anal tubercle of moderate size; six spinnerets small, closely crowded, with anterior pair stoutest, approximated; position of colulus indicated by a tuft of black hairs; tracheal spiracle with distinct lip near base of spinnerets but no tubercle.

Color in alcohol. Carapace: almost uniformly mahogany reddish brown with a few white lanceolate hairs and slight iridescence. Chelicerae reddish brown, streaked with dark brown; maxillae and lip nearly the same with yellowish white tips. Sternum brown. Legs: first legs with coxae and trochanters brown, femora reddish brown. Patellae and tibiae yellowish white, metatarsi reddish brown, tarsi brown; second and third legs unicolorous yellowish white; fourth legs with coxae, trochanters and proximal ends of dorsal surfaces of femora yellowish white, remainder of femora reddish brown, patellae reddish brown at base but elsewhere yellowish white, tibiae yellowish white with lateral reddish brown stripes; metatarsi and tarsi brownish. Abdomen: dorsal shield reddish brown; lateral sides dark brown with a narrow oblique white bar near posterior end; venter dark brown bordered by a row of yellowish dots on each side.

Female allotype. Total length 3.71 mm. Carapace 1.66 mm. long (considerably overlapped by abdomen), 1.41 mm. wide, .96 mm. tall and, therefore, about .68 as tall as wide; other features essentially as in male.

Eyes. Seen from in front, anterior row recurved so that a line tangent to dorsal borders of ALE cuts off about one eighteenth of the diameter of AME. Posterior row wider than anterior row in ratio of about 13 : 11, wider than middle row in ratio of about 13 : 10. Quadrangle of laterals wider than long in ratio of about 13 : 9. Total eye space occupies about five sevenths of the length of the carapace. Ratio of eyes AME : ALE : PME : PLE = 18 : 9.5 : 2.3 : 9. AME barely separated from one another, from ALE by one eighteenth of their diameter. Middle row closer to ALE than to PLE in ratio of 15 : 11. Height of clypeus equal to one sixth of the diameter of AME. Clypeus decorated with a rich coat of long white lanceolate hair which shows some iridescence, two long white bristles beneath each AME, and three long upturned yellowish bristles in lower angle between AME.

Chelicerae. Fairly robust, vertical, parallel; well rounded in front where there are many short white loose scales; no basal boss observed; basal segment .57 mm. long. Fang fairly robust, evenly curved. Fang groove distinct; with two promarginal teeth, inner small, outer of moderate size; retromargin with a single typical fissidentate tooth.

Maxillae, Lip, and Sternum. Essentially as in male.

Legs. Tibial index of first leg 18, of fourth leg 12.

	Femora	Patellae	Tibiae	Metatarsi	Tarsi	Totals
(measurements in mm)
1.	1.05	.63	.77	.54	.45	3.44
2.	.83	.48	.57	.54	.35	2.77
3.	.83	.43	.51	.61	.38	2.76
4.	1.28	.60	.96	.83	.43	4.10

Spines. First leg: patella 0; elsewhere as in male except tibial and metatarsal spines more robust. Second leg: femur only dorsal 0-0-1-1; patella 0; tibia only ventral 1r-1r-1r; metatarsus as in first. Third leg: metatarsus only prolateral 0-2, retrolateral 0-1; elsewhere as in male. Fourth leg: femur dorsal 0-1-0-1; patella 0; tibia only ventral 1p-0-2; metatarsus as in male. No palpal spines observed.

Abdomen. Much more robust than in male; longer than wide in ratio of about 3 : 2, widest in middle; with no indication of a dorsal shield; other features essentially as in male.

Epigynum. Simple; with a shallow acute posterior marginal notch; main part of plate somewhat swollen through middle; near anterior border are two depressions nearly two diameters of one of them apart (Fig. 372).

Color in alcohol. Carapace: nearly uniformly reddish brown, covered by many white hairs to give a grayish appearance; eyes on black spots. Palps yellowish white. Chelicerae reddish brown; maxillae and lip much the same with whitish tips. Sternum brown. Legs: first pair with reddish brown trochanters and femora, tarsi brown, other segments yellowish white with reddish brown markings, coxae with a single small prolateral and retrolateral spot, patellae reddish brown at base and with a distal dorsal spot, tibiae with a dorsal and a prolateral stripe on each; second leg yellowish white with reddish brown markings the most important of which are a broad prolateral femoral stripe becoming a bar across tip of femur and base of patella and then continuing as a prolateral stripe to tip of tibia, also a narrow dorsal tibial stripe in distal half; other legs somewhat like second with variations. Abdomen: reddish brown with four pairs of dorsal light spots in anterior three fourths; lateral sides brown with many narrow yellowish dotted lines; venter dark brown from genital groove to base of spinnerets bounded on each side by a row of yellowish dots and bearing centrally two more rows of yellowish dots.

Type locality. Male holotype from Canal Zone Biological Area, June, 1939; female allotype from the same locality, Aug., 1936. Numerous paratypes of both sexes from: Canal Zone Biological Area, June–July, 1934; June–July, 1936; June–July, 1939; El Valle, R. P., July, 1936; Chilibre, C. Z., July, 1939; C. Z. Forest Reserve, C. Z., Aug., 1939; El Cermeno, R. P., Jan.–Feb., 1940 (Zetek).