User:Kaldari/Notes on jumping spiders of the genus Zygoballus in North America

This is a draft document.

The salticid genus Zygoballus comprises a group of 20(?) species ranging across North and South America. The genus has never been systematically studied and no revisions of Zygoballus have been published to date.

Taxonomy

Family Salticidae Blackwall 1842
Genus Zygoballus Peckham & Peckham 1885

Attus [in part]: Hentz 1845: 202.
Zygoballus Peckham & Peckham 1885: 81–82; Peckham & Peckham 1895: 172; Peckham & Peckham 1909: 577–578; Kaston 1948: 496.
Eris [in part]: Peckham & Peckham 1888: 56.
Rhene [in part]: O. P.-Cambridge, 1896: 162.
Amerotritte Mello-Leitão 1944: 375.
Gastromicans [in part]: Mello-Leitão, 1945: 284.

Type species. Zygoballus rufipes Peckham & Peckham 1885, by monotypy.
Amerotritte: Amerotritte lineata Mello-Leitão 1944, by monotypy.

Description. Small (2–6 mm) dendryphantine jumping spiders widely distributed across North and South America.

In the species descriptions, all characters are assumed to be as in the genus description except where otherwise noted.

Zygoballus nervosus (Peckham & Peckham 1888)

• Eris nervosus Peckham & Peckham 1888: 56, plate 1, fig. 39, plate 3, fig. 39 (female holotype in Museum of Comparative Zoology).
• Zygoballus terrestris Emerton 1891: 231, plate 17, fig. 5 (male and female holotypes in Museum of Comparative Zoology).
• Z. nervosus Peckham & Peckham 1909: 580, plate 50, fig. 8, plate 51, fig. 12; Kaston 1948: 497, plate 100, figs. 1863–1864, plate 101, figs. 1876–1877; Roewer 1954: 1018; Bonnet 1959: 5013.

Description

MALE.

Pedipalp. Tibial apophysis stout, elongate triangular, tip attenuate. Tegulum roughly circular, prominent shoulder on prolateral side.

Zygoballus rufipes Peckham & Peckham 1885

• (?) Attus parvus Hentz 1846: 358, plate 8, fig. 17.
• Zygoballus rufipes Peckham & Peckham 1885: 82, plate 2, fig. 12 (male holotype in Museum of Comparative Zoology?).
• Zygoballus bettini Peckham & Peckham 1888: 89, plate 1, fig. 68 (types?); Emerton 1891: 230, plate 17, fig. 4; ...
• Zygoballus bettina Marx 1890: 577.
• (?) Zygoballus parvus Banks 1898: 288.
• Eris bettini Prószyński 1976: 149.

Life cycle

Zygoballus rufipes spiderlings are sexually dimorphic by the 3rd instar (Barnes 2010). Adult males are dimorphic in body size, while adult females are monomorphic. Faber suggests that this may result from the males maturing at two different instars (Faber 1994). Both mature and immature individuals are found throughout the year (Kaston 1948). Faber, collecting in Wisconsin, reports large morph males being most common in late summer. He also reports finding gravid females only in June.

Zygoballus sexpunctatus (Hentz 1845)

• Attus sexpunctatus Hentz 1845: 202, plate 17, fig. 14 (no type specimen designated). (Not Attus sexpunctatus Simon 1868: 579.)
• Zygoballus sexpunctatus Peckham & Peckham 1888: 89, plate 1, fig. 67, plate 6, fig. 67; Simon 1903: 863, figs. 1017–1022; Peckham & Peckham 1909: 583, plate 51, fig. 11; Roewer 1954: 1019; Bonnet 1959: 5014.

Etymology

Derived from the Latin sex meaning "six" and punctum meaning "spot".

Geographic Range and Records

Eastern United States. North to Long Island, south to Florida, west to Texas. Most commonly found in the southern states. USA: Alabama: Chambers or Tallapoosa, Lee or Macon, Talledega; Arkansas: Benton, Jefferson, Pulaski; Florida: Alachua, Charlotte, Collier, Columbia, Duval, Hamilton, Marion, Okaloosa, Orange, Osceola, Palm Beach; Georgia: Bibb, Chatham, Clarke, Habersham, Jefferson, Lowndes, McDuffie or Wilkes ("Washington to Thomson"), Screven, Toombs; Ohio: "Cincinnati region"; Illinois: Alexander, Jackson, Pope, "southern Illinois"; Iowa: Story; Louisiana: Caddo, Ouachita; New York: Nassau; North Carolina: Johnson, Durham?, "Swannanoa Valley", Washington; Maryland: Anne Arundel, Cecil, Caroline, Montgomery, Prince Georges, Talbot, Somerset; Mississippi: Amite, Claiborne, Covington or Smith, Washington, "northern Mississippi"; Missouri: Phelps; South Carolina: Barnwell, Greenville, Pickens, Richland, "Coastal Plain"; Tennessee: Blount, Davidson, "Memphis region"; Texas: Nacogdoches, Travis, Wichita; Virginia: "Virginia Peninsula".

Description

MALE.

Carapace. Clypeus covered with white, elliptic scales. Scale covering extends from clypeus around sides of carapace, ending beyond PME. Long white spatulate scales overhang oral margin. Prolateral surface of chelicerae sparsely covered with white, elliptic scales and long hairs. Lateral edge of carapace is fringed with white scales immediately above carapace lip. Large spot of white scales on top of carapace, directly between PLE. Spot is wider than long and approximately one third width of carapace. A few white scales may be found immediately posterior to PLE. Scales are weakly iridescent and may appear silvery blue under alcohol. Remainder of carapace is bare with a leathery appearance (chagrinée).

Eyes. Ratio of diameters of AME : ALE : PME : PLE is 8 : 5 : 1 : 4. PME are closer to ALE than PLE in ratio of 3 : 4.

Male from Davidson County, Tennessee. Total length 3.3 mm, carapace length 1.74 mm, carapace width 1.56 mm, carapace height 1.13 mm, abdomen width 1.29 mm, abdomen length 1.90 mm. Eye diameters: AME 0.42 mm, ALE 0.23 mm, PME 0.05 mm, PLE 0.21 mm. Clypeus: 0.07mm. Ocular quadrangle occupies fifteen twenty-fourths of the length of the carapace. Leg formula 1423.

• Width Ocular Field I: 1.32 mm
• Width Ocular Field II: 1.15 mm
• Width Ocular Field III: 1.61 mm
• Length Ocular Field: 1.10 mm

	Femora	Patellae	Tibiae	Metatarsi	Tarsi	Totals
(measurements in mm)
1.	1.61	0.82	1.42	0.87	0.55	5.27
2.	0.97	0.39	0.68	0.60	0.37	3.01
3.	0.84	0.35	0.53	0.52	0.36	2.60
4.	1.33	0.48	0.91	0.70	0.41	3.83
Palp	0.79	0.37	0.29	—	0.44	1.89

Width of femur I 0.67 mm (femur index 2.4). Width of tibia I 0.29 mm (tibial index 4.9).

Notes

The Peckhams in 1909 described the cephalothorax of the male as "bronze-brown" in color. Hentz's description and the Peckham's earlier 1888 description both describe the male cephalothorax as black. All live male specimens I have seen have a black (or virtually black) cephalothorax. The color when preserved in alcohol, however, is typically dark reddish brown with black spots around the eyes.

• 
  Carapace and chelicerae (lateral view)

References

• Kaston, B. J.; Kaston, Elizabeth (1953). How to Know the Spiders (1st ed.). Dubuque, Iowa: W. C. Brown Co.