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(Figs. 5- 8)
Holotype. Worker, with the following measurements : HL, 0.82 mm; HW, 0.84 mm; SL, 0.82 mm; EL, 0.20 mm; MFC, 0.32 mm; EW, 0.16 mm; FL, 0.76 mm; LHL, 0.70 mm; PW, 0.60 mm; ES, 3.2 mm; SI, 100; and CI, 102.44.
Description. (Figs. 5 and 7). Appearance is supericially similar to T. sessileHNS, although generally larger. The following mean values (± SD) of measurements were the made from 148 workers: HL, 0.77 ± 0.06 mm; HW, 0.75 ± 0.07 mm; SL, 0.77 ± 0.08 mm; EL, 0.19 ± 0.02 mm; MFC, 0.29 ± 0.03 mm; EW, 0.15 ± 0.01 mm; FL, 0.69 ± 0.05 mm; LHL, 0.63 ± 0.05 mm; PW, 0.54 ± 0.06 mm; ES, 2.75 ± 0.41 mm; SI, 99.50 ± 7.02; and CI, 95.80 ± 7.29. The worker is bicolored with the head and mesosoma rufous in color; the gaster is black to brown, although in older workers this color fades to gray. The head is concave at the vertex and ocelli are absent. The antennal scape surpasses the vertex by approximately one third its total length; the lagellum possesses 12 segments. The anteroclypeal margin has a shallow concavity that does not surpass the antennal sockets . The mandibles with four teeth and seven denticles with the apical tooth the longest, slightly larger than the subapical tooth, the basal angle is not distinct and the curve between the masticatory and basal margin is smooth and not interrupted. In total, six anterior clypeal setae overhang the mandibles. Erect hairs are absent on the dorsum of the mesosoma though are present on propleuron, coxae and gastral sternites, and posterior tergites.
Material Examined. (LACM, PSWC, CSUF). California : Mt. Laguna , San Diego County (W. S. Creighton ); Sagehen Creek , Nevada County (P. S. Ward); Eagle Lake, Lassen County (P. S. Ward). Nevada: Kyle Canyon, Clark County (A. C. Cole, S. Cover).
Holotype. Worker, collected by P. S. Ward and deposited in the MCZ at Harvard University, bearing the following labels:
CA Nevada Co.
39° 26'N, 120° 14'W
1,920 m, 27-VI-1994
Fig. 4. Multivariate plot of head width x head length x altitude between concolorous T. sessileHNS and the bicolored ant that seemed similar to T. sessileHNS. Note that all measured characters followed this altitudinal cline and that only one set is presented here.
grd. forager(s) pine-fir forest
This specimen also will carry a label designating it as the holotype. Additional material from this series of collected workers resides at the UCDC and LACM.
Male. (Fig. 8). The following mean values (± SD) ofmeasurements were the made from two males in the collection of the LACM: HL, 0.68 ± 0.06 mm; HW, 0.68 ± 0.01 mm; SL, 0.73 ± 0.01 mm; EL, 0.26 ± 0.01 mm; MFC, 0.20 ± 0.03 mm; EW, 0.21 ± 0.01 mm; FL, 0.75 ± 0.01 mm; LHL, 0.64 ± 0.01 mm; PW, 0.76 ± 0.01 mm; MML, 1.08 ± 0.03 mm; WGL, 3.1 ± 0.31 mm; ES, 5.46 ± 0.37 mm; SI, 107 ± 2.39; and CI, 100 ± 4.16. The vertex of the head is flat to slightly convex, three ocelli at the vertex. Antennae with 13 segments, the scape surpasses the vertex of the head by one half its length. Apical tooth longest, masticatory margin of mandible with a series of small denticles. The male is concolorous and rufous or piceous brown, and is thus very similar to T. sessileHNS, though generally smaller.
Queen. (Fig. 6). The following mean values (± SD) of measurements were the made from four alate queens in the collection of the LACM: HL, 0.93 ± 0.03 mm; HW, 1.03 ± 0.02 mm; SL, 0.87 ± 0.02 mm; EL, 0.26 ± 0.01 mm; MFC, 0.41 ± 0.02 mm; EW, 0.2 ± 0.02 mm; FL, 0.84 ± 0.02 mm; LHL, 0.74 ± 0.04 mm; PW, 1.04 ± 0.0.03 mm; WL, 1.23 ± 0.04 mm; WGL, 4.08 ± 0.22 mm; ES, 5.20 ± 0.42 mm; SI, 93.60 ± 1.63; and CI, 110 ± 1.28. The queen is bicolored with the head and mesosoma rufous in color; the gaster is black to brown, although in older workers this color fades to gray. The head is slightly concave at the vertex and three ocelli are present. The antennal scape surpasses the vertex by approximately one third its total length; the lagellum possesses 12 segments. The anteroclypeal margin has a shallow concavity that does not surpass the antennal sockets. The mandibles with seven teeth and seven denticles with the apical and subapical teeth the longest, the basal angle is not distinct and the curve between the masticatory and basal margins is smooth and not interrupted. A total of six anterior clypeal setae overhang the mandibles. Erect hairs are absent on the mesosoma and gaster. The queens of this species seem slightly larger than T. sessileHNS queens.
Etymology. The species is named in honor of Dr. Fred Schreiber, a professor for >35 yr at California State University-Fresno and mentor to countless students .
Remarks. This species is supericially similar to T. sessileHNS, but this bicolored ant can be distinguished from the latter by its head and mesosoma (which are rufous ) and its gaster (which is black). The workers and queens are, on average, larger than T. sessileHNS, although males seem smaller and are concolorous. The comparisons in size between the sexual castes of T. sessileHNS and T. schreiberiHNS are made using very low numbers of individuals; caution should be exercised when using these data. I do not believe that this species is the T. dimmockiHNS of Fisher and Cover (2007) because workers of both species are aggressive toward one another and were never found in the same nest.
Found most commonly in these habitats: 1 times found in on swimming pool surface, 1 times found in pine/fir woodland, 1 times found in pine-juniper woodland, 1 times found in Pinus jeffreyi forest, 1 times found in sagebrush-juniper-pine.
Found most commonly in these microhabitats: 1 times nest under rock, 1 times nest under log and in adjacent black oak litter, 1 times ground foragers, 1 times ground forager(s).
Collected most commonly using these methods: 1 times hand collecting.
Elevations: collected from 1600 - 2145 meters, 1936 meters average
Collect Date Range: collected between 1990-07-16 and 2018-06-25