Το Ημερολόγιο του Pardosa lapidicina group

Pardosa is a scary genus when it comes to doing species identifications. There may be too many similar species. There may be too much variation within each species. There is strong sexual dimorphism in many species that doubles the difficulties. I'd rather think positively and make the assumption that there is some way to tell species apart. The descriptions in scientific literature all seem similar, and they are very hard to understand without photographs. So, the only solution is to find and document local populations thoroughly. Trying to get a sampling of males, females and juveniles. Hopefully we can find places where only a single species is present. Then we can start to see similarities and get an idea which characteristics are too variable to be useful. Once we can separate our observations into species, we can start matching up our unidentified species with the ones that have been described.

Pardosa includes several species groups, and one of the more easy to recognize is the lapidicina group. The carapace is relatively wide and short like those of fishing spiders. The posterior eyes form a trapezoid that is wider than tall. The patterns are generally light with fine markings. The eyes are black. The legs are often strongly banded. They are often near water. And, they like sitting on rocks, big or small. They are easily confused with Arctosa littoralis which lack perpendicular spines on tibia IV and have a more closely spaced posterior eye grouping. Both can be found in the same area.

This is a call for Pardosa lapidicina group photo studies of local populations, local meaning within about a 1 acre area. Preferably they should be from the western U.S. and Mexico, but observations from the eastern U.S. and Canada might be useful in the future. Photos should be sharp enough that some of the spines are visible and an occasional ventral view would be appreciated. Any field identifications tips would be very helpful.

Eric

Many scientific articles can be found at World Spider Catalog but they have to be read with the understanding of author at the time. For example, the original description of mercurialis won't have any comparative notes on the 4 species described subsequently. The range shown for sierra in 1959 is invalid because Barnes incorrectly synonymized atromedia and sura with it. Another problem is that specimens preserved in alcohol were used to write most of the early pattern and color descriptions and have limited value for identifying live spiders. The 7 species below include all that either have been reported in Texas or are in adjoining states and might be in Texas.

1885 Pardosa lapidicina; original description by Emerton, specimens from Massachusetts and Connecticut
1898 Pardosa sierra; original description by Banks, specimens from Baja California
1904 Pardosa mercurialis; original description by Montgomery, specimens from Austin, TX
1941 Pardosa sura; original description by Chamberin & Ivie, specimens from California
1955 Pardosa steva; original description by Lowrie & Gertsch, specimens from Wyoming
1959 Pardosa sura wrongly determined to be a synonym of sierra by Barnes
1959 Pardosa vadosa; original description by Barnes; specimens from Arizona
1959 Pardosa valens; original description by Barnes; specimens from Arizona
2010 Pardosa sura; restablished as a species by Correa-Ramirez, Jimenez, & Garcia

Pardosa sierra is almost certainly not in Texas
Pardosa sura is almost certainly in west Texas
Pardosa valens is likely in west Texas
Pardosa steva might be in west Texas
Pardosa atromedia, a California species, was also wrongly synomymized with sierra and later restablished as a species.

I parked near the boat ramp at the southeast corner of the park in the morning. The temperature was mild and it was mostly sunny. I found three significant habitats in the immediate area. There was a small raised plateau with sparse vegetation, a long, low limestone bluff along the lake, and a small gentle sloping muddy area next to the lake. The last had recently been underwater and was now covered with low vegetation hosting a large number of caterpillars.
A large number of adult Pardosa lapidicina group spiders were seen on the bluff. They appeared to represent a single species which showed obvious sexual dimorphism. The females had banded legs and were pale tan and darker gray overall. The males had fainter leg banding and were a darker reddish brown overall. Their bodies had patches of lighter, yellowish-tan hairs. The cymbium on the pedipalp was claw shaped and dark brown in color.
Many smaller Pardosa representing at least two additional species were found on the plateau and muddy slope along with two late juvenile females of the lapidicina group species. The lapidicina group juveniles were lighter than the adults and in shades of gray with a slight tan tint.
The spider distribution may have been a matter of food availability. The bluffs were largely unvegetated, however there were numerous Pygmy Grasshoppers. The vegetation of the other two areas supported a greater diversity of small arthropods that may have appealed to smaller spiders.

Each location has its own benefits. In this case a single lapidicina group species was apparently isolated, and I have a good selection of both male and female adults photos to work with. This is probably the best place yet for me to try for a species identification. Like most of the lapidicina group species, the male and female had similar body lengths of about 0.25". Two gravid females were obvious exceptions with body lengths of about 0.34". Females with egg sacs had returned to their original lengths. Lengths provided in the scientific literature often show a much wider range of female length, and this is probably why. Carapace length would be a more consistent measure, and the plasticity of the abdomen suggests that reporting body length to a hundredth of a millimeter is overkill.

There are perhaps 3 lapidicina group species in eastern and central Texas, specifically lapidicina, mercurialis, and vadosa. The following link shows the ranges of these species according to Barnes, 1959:
http://eaneubauer.ipower.com/lapidicina+mercurialis+vadosa.jpg
Clearly the ranges are incomplete as there are iNat observations of lapidicina group species in eastern Texas and other Gulf States as well. An additional 3 species can possibly be found in the Trans-Pecos region, specifically sura, steva, and valens. Barnes reported sierra and vadosa there. The former were presumably incorrectly synonymized sura. Pardosa steva and valens were reported across the border in both New Mexico and Mexico, so there is a good chance of them being in the Trans-Pecos.