Studies on California ants: a review of the genus Temnothorax (Hymenoptera, Formicidae)

Abstract The following ten new species of the ant genus Temnothorax are described and illustrated: T. anaphalantus (California, Baja California), T. arboreus (California), T. caguatan (Oregon, California, Baja California), T. morongo (California, Baja California), T. myrmiciformis (California, Baja California), T. nuwuvi (Nevada), T. paiute (California, Nevada), T. pseudandrei (Arizona, California), T. quasimodo (California) and T. wardi (California). A key to workers of the twenty-two Temnothorax species known or expected to occur in California is provided.

The workers of Temnothorax species are generally small. Colonies are typically monogynous, although facultative polygyny has been documented in several species (Alloway et al. 1983, Buschinger 1974, Buschinger and Linksvayer 2004, Rüppell et al. 1998. Colony populations are usually quite small, often with less than 100 workers (Beckers et al. 1989). However, several studies have found colonies of some species to be widely dispersed with several to many satellite nests (Alloway et al. 1983, Foitzik and Heinze 2001, Partridge et al. 1997. Many species are arboreal, living within hollow stems, old beetle or termite galleries, or in galls (Mackay 2000). Temnothorax species appear to be trophic generalists, feeding on a wide variety of scavenged items, including the elaiosomes of seeds (Espadaler 1997, Fokuhl et al. 2012. None have been documented to be active or aggressive predators.

Methods
The specimens utilized in this study are principally from two collections, that of the University of California at Davis [UCDC]  were also examined. Paratypes of most of the California species described by Mackay (2000) were donated to LACM by Dr. Mackay, University of Texas at El Paso [WPMC]. Types of the new species described here will be deposited in the aforementioned institutions, as well as the American Museum of Natural History, New York, New York, U.S.A. [AMNH], California Academy of Sciences, San Francisco, California, U.S.A. [CASC], and National Museum of Natural History, Washington, D.C., U.S.A. [USNM]. All specimen data for the new species, along with images, have been deposited on the AntWeb public database (http://www. antweb.org/) and are accessible through links to unique specimen identifiers in the text. The data can be also downloaded as an Appendix tab-delimited file.
The diagnoses accompanying the descriptions are intended to distinguish between the new species and others in the faunas of California and adjacent states, and not the North American fauna as a whole.
Where available, we provide illustrations and descriptions of general male morphology for the new species described here. However, the males of Temnothorax are still known for only a handful of taxa and we feel that detailed descriptions of genitalia and wing venation are not necessary for diagnostic purposes.
In the descriptions below, the following acronyms are used ( Figure 1A-D):

EL
Eye Length: Maximum length of the compound eye in profile, including non-pigmented facets. All measurements are given in millimeters. Ranges are followed by mean in parantheses. All measurements and color photographs were made using a Leica MZ 16 stereomicroscope with a JVC digital video camera. Images were processed using Syncroscopy Automontage and Zerene Systems Zerene Stacker software and cleaned and adjusted using Adobe Photoshop. Maps were generated with ArcMap. In the material examined sections GPS coordinates have been rounded off to reflect the precision with which a record has been georeferenced or are followed by an error term in meters (e.g., 37.23100°-122.10853° ±440 m).
Description. Worker measurements ( Head longer than broad in frontal view, lateral margins distinctly convergent above; posterior margin weakly concave in middle. Antenna 12-segmented; scape ending below posterior margin by more than twice its apical width; terminal club distinctly three-segmented. Eye small and moderately bulging; IOD 2.81-3.12 × EL; EL 0.93-1.10 × OMD. Median lobe of clypeus without submedian carinae. Head, including median lobe of clypeus and supraclypeal area, dull and finely reticulate; very fine rugae curving around antennal fossae and extending a short distance back from frontal lobes. Vertex, frons and frontal lobes without erect setae; clypeus with a single erect seta on each side of median lobe in addition to usual long curled setae along anterior margin.
Petiole node highest anteriorly, rounded dorsal face sloping distad into posterior face; subpetiolar process short and thick. Postpetiole rounded in profile and quadrate in dorsal view. Both nodes dull and finely reticulate, without rugae and each with several flattened erect setae that are longer than those of mesosoma.
Gaster, in dorsal view, 2.51-3.02 times wider than postpetiole; basal half of first tergite slightly shiny and distinctly roughened, becoming increasingly shiny and  Head longer than broad, margins behind eyes slightly convergent and broadly rounded into weakly convex posterior margin. Eyes large and strongly bulging; IOD 1.38-1.50 × EL; OMD very short, about equal to transverse diameter of anterior ocellus; interocellar distance 2.30-2.70 and ocellocular distance 2.60-2.70 times diameter of anterior ocellus. Antennae 13-segmented. Scape more than half of IOD. Head uniformly punctate, with fine rugae present on clypeus and in the area between antennal fossae and compound eye, extending from lateral clypeal margin to approximately 1/2 length of compound eye. Pilosity same as in worker, but with clypeal setae barely surpassing the clypeal margin in full face view.
Mesosoma robust, WL 1.99-2.10 × PW. Propodeal spines absent. Sculpture punctate, weakening to fine reticulation on mesopleuron and dorsal surfaces of mesonotum. Mesoscutum with two pairs of erect short, blunt setae; several pairs of similar setae along the lateral and posterior margins of mesoscutellum.
Petiole subtriangular, with petiolar node rounded in profile; subpetiolar process a small rounded lobe, approximately half as high as length of propodeal lobes.
Gaster 2.82-3.09 × PPW in dorsal view. Uniformly smooth and shiny except for traces of fine reticulation on the anterior margin of first tergite. Sparse decumbent pilosity present on the first gastric sclerites, with several short, erect, blunt tipped setae along the posterior margins of all gastric sclerites.   Etymology. From Greek: anaphalantos, with a bald forehead, in allusion to the lack of erect setae on the vertex and posterior areas.
Remarks. The reticulate head and mesosoma, without any obvious rugae, and the greatly reduced standing pilosity will separate this from any other western species. In Mackay's key (2000) it will run to T. silvestrii from Arizona, but differs from both T. silvestrii and T. morongo (described below) by the greatly reduced pilosity, lack of rugae, and the much thicker, short propodeal spines (Figures 19A,D).
Little is known of the ecology of this species. Some specimens were collected from a pitfall sample in an area that is mostly oak grassland but including some coastal scrub and riparian scrub. Other records are from chaparral and a cottonwood riparian area. The only nest sample of T. anaphalantus was collected from dead wood in montane chaparral.

Temnothorax andrei (Emery, 1895)
http://species-id.net/wiki/Temnothorax_andrei Figure 21 Leptothorax ( Diagnosis of worker. Promesonotum flat, followed by sloping dorsal face of the propodeum, so that in lateral view propodeal angles are relatively low on the declivity; head shiny, varying from weakly sculptured to smooth; petiole node robust and triangular in profile; propodeal spines reduced to small angles; body color dark brown. Head longer than broad in frontal view, lateral margins very weakly curved, posterior margin flat to weakly curved. Antennal scape ending below posterior margin by more than its apical width; apical club distinctly 3-segmented. IOD 3.04-3.33 × EL; EL 0.75-0.91 × OMD. Mandible finely longitudinally rugose. Clypeus with 1 or 2 short fine carinae on either side of median carina. Dorsum of head shiny, mostly smooth between scattered fine piligerous punctures; area around frontal carinae moderately shiny and weakly reticulate; malar area with several short fine longitudinal rugae, interspaces dull and sharply reticulate; posterolateral angles of head moderately shiny and weakly reticulate. Dorsum of head with sparse short, fine setae. Mesosoma slender, WL 1.97-2.11 times longer than PW; mesosomal dorsum nearly flat in profile before sloping down to obtuse propodeal denticles. Mesosomal dorsum moderately shiny and weakly reticulate but pronotum posteriorly with transverse smooth band; side of pronotum moderately shiny and irregularly rugulose, interspaces inconsistently reticulate; posterior face of propodeum dull and reticulate. Metafemur 3.54-3.97 times longer than wide in dorsal view. Entire length of dorsum with >20 flattened setae that are distinctly longer than those of frons.
Petiole without anterior peduncle; node robust and subtriangular, no higher than thick, summit subacute; subpetiolar tooth short and acute. Postpetiole profile low; in dorsal view node 1.42-1.45 times width of petiole node. Both segments moderately shiny and mostly finely reticulate. Each node with 4-6 setae similar to those of mesosoma.
Gaster in dorsal view 2.86-3.02 times wider than postpetiole; disc of first tergite smooth and shiny between sparse piligerous punctures; disc with sparse suberect flattened setae similar to those of mesosoma and scattered finer prostrate pubescence.
Head and body dark brown, gaster darker posteriorly. Gyne and male unknown. Etymology. From Latin, arboreus -of trees, in reference to this being an arboreal species. Remarks. This species is similar to T. nitens (Emery 1895) and in the key by Mackay (2000) it will run, with some difficulty, to T. melinus (Mackay 2000), a synonym of T. nitens (Ward 2005). From T. nitens it differs in the much darker color, the obtuse propodeal denticles that are shorter than the subpetiolar tooth, and the considerably more robust petiole node (Figure19B & 21E).
As the name suggests, T. arboreus is an arboreal species. Workers have been collected from the trunk and beaten from foliage of Pinus jeffreyi. That this ant is arboreal further distinguishes it from T. nitens, a species that nests in soil, often under small covering objects such as stones.
A couple of collections of similar species are known from southeastern Arizona, but we feel the relationship of these samples will be better understood only when more material becomes available. Diagnosis of worker. Antenna 11-segmented; propodeal spines distinct and more than half as long as distance between their bases; node of petiole node subrectangular in profile; head and mesosoma coarsely rugose and with reticulate interspaces. Head longer than broad in frontal view; lateral margins parallel or nearly so; posterior margin transverse. Antenna 11-segmented with indistinct apical 3-segmented club; scape ending below posterior margin by more than its apical width. Eye small; IOD 3.04-3.44 × EL; EL 0.88-1.04 × OMD. Mandibles coarsely longitudinally rugose. Median carina of clypeus flanked on each side by three about equally strong carinae. Dorsum of head with coarse longitudinal rugae that diverge slightly posteriorly; posterior one-third to one-half with coarse rugoreticulosity; interspaces slightly shiny with shallow punctures. Dorsum with sparse erect, stiff, blunt-tipped yellowish setae; ventral surface with several longer acute setae on each side.
Mesosoma slender, WL 1.91-2.03 × PW; profile of mesosomal dorsum nearly flat, sometimes weakly depressed at metanotal suture. Propodeal spines well developed, PSI 22.4-26.4, slightly down-curved in profile and about as long as distance between their bases. Dorsum and sides with strong, well-separated longitudinal rugae, interspaces contiguously punctate and slightly shiny; pronotum anteriorly usually with some reticulae. Metafemur 3.72-4.23 × longer than thick in dorsal view. Dorsum with 20+ short standing setae along entire length.
Petiole with anterior peduncle; node in profile subrectangular, dorsal face sloping posteriorly, flat to slightly convex; posterior face short; subpetiolar tooth prominent, usually acute; Postpetiole rectangular in dorsal view and 1.23-1.38 times as wide as petiole node. Petiole node rugoreticulate, postpetiole similar and with weak longitudinal rugae at sides; both nodes finely reticulate between rugae. Each with 6-10 standing setae that are longer than those of mesosoma.
Gaster, in dorsal view, 2.40-2.66 times wider than node of postpetiole. Disc of first tergum smooth and shiny between sparse, distinct piligerous punctures. All segments with numerous long, narrowly rectangular to subacute yellowish setae.
Head and body light to dark reddish-brown, mesosoma lighter than either head or gaster.
Gyne measurements (1 measured Head longer than broad, margins approximately parallel in frontal view and broadly rounded into transverse posterior margin. Antennal scape extending back to level of lateral ocellus. Eye large and moderately convex, IOD 2.57 × EL in frontal view; EL 1.50 × OMD. Sculpture and pilosity about as in worker. Mesosoma slender, WL 1.78 × PW. Mesonotum flat in profile. Propodeal spines thick at base, about half as long as infraspinal distance. Mesoscutum with conspicuous longitudinal rugae, and interspaces weakly reticulate; mesoscutellum also rugose, but more irregularly, underlying irregular sculpture more pronounced than on mesoscutum. Side of pronotum duller and with distinct fine reticulum; mesepisternum shinier and finely reticulate anteriorly to longitudinally rugose posteriorly; propodeum dull, finely reticulate with striae in anterior portion. Pilosity suberect to erect, short (less than 0.1 mm), not flattened and relatively sharp-tipped.
Remainder as described for worker; gaster 2.95 × as wide as postpetiole.
Male measurements (mm) ( 2 measured Head longer than broad, margins behind eyes slightly convergent and broadly rounded into weakly convex posterior margin. Eyes large and strongly bulging; IOD 1.57-1.58 × EL; OMD very short, about equal to transverse diameter of anterior ocellus; interocellar distance 2.30-2.40 and ocellocular distance 2.20-2.30 times diameter of anterior ocellus. Scape less than a third the length of IOD. Head finely reticulate and with regular longitudinal rugae dorsally and circling the eyes. Dorsum of head with erect setae which are long and sharp-tipped.
Summit of petiole node low, broadly convex in profile; subpetiolar process absent. Mesosoma and petiolar segments brownish yellow; appendages yellow; head and gaster reddish brown.  Etymology. When Hernán Cortéz was conquering central Mexico, the Nahua speaking people related to him tales of a fabulous land, ruled by women, far to the northwest that was rich in gold and gems. They named this land "Caguatán", the Land of Women. This tale presumably inspired Cortéz and other avaricious conquistadors to search for this marvelous land, ultimately leading the Spaniards to the Californias. The name California is that used by some fiction writers and explorers of the time for a mythical land inhabited by beautiful black women ruled by their queen, Calafia.
Remarks. Because the antennae are 11-segmented and the propodeal spines are long, among our California species T. caguatan can only be confused with T. rugatulus, which has a shorter petiole node with acute top and relatively more slender hind femur ( Figure 20E, F; see key for measurements). The latter also typically nests in soil, commonly under covering objects such as small stones, although collections are known from dead wood and arboreal sites (P. S. Ward pers. comm.).
This widely distributed arboreal species has been collected in a variety of habitats, ranging from oak woodland to grey pine and Sequoia forests, but the preponderance of the records have been from oak woodland. It has been found in association with a number of tree and shrub species: Arctostaphylos spp., Pinus jeffreyi, Quercus agrifolia, Q. chrysolepis and Q. kelloggii. Nest samples have been taken from dead branches of all three Quercus species and one was from a dead branch of P. jeffreyi. (Cole, 1957) http://species-id.net/wiki/Temnothorax_carinatus Figure 22 Leptothorax (  Head longer than broad in frontal view; posterior margin transverse and lateral margins essentially parallel. Antenna 12-segmented; scape slightly exceeding posterior margin; apical club distinctly 3-segmented. Eye small, IOD 2.80-3.13 × EL; EL about 0.75-0.92 × OMD. Mandibles coarsely longitudinally rugose. Head opaque and finely reticulate between fine longitudinal rugae; interrugal spaces of clypeus shiny and weakly sculptured. Sparse yellowish very short and stout erect setae on front of head; hypostomal area with scattered very short fine setae.

Temnothorax carinatus
Mesosoma slender, WL 2.06-2.24 × PW; mesosomal dorsum essentially flat in profile. Propodeal spines well developed, distinctly longer than distance between their bases; in profile directed distad or slightly down-curved; in dorsal view slightly incurved. Entire mesosoma opaque or nearly so between slightly irregular longitudinal rugae; anterior margin of pronotal disc with sharp transverse carina. Dorsum with sparse yellowish short, flattened setae. Metafemur slender, 3.98-5.32 times longer than wide in dorsal view.
Petiole node robust and cuboid in profile; acute subpetiolar tooth present. Postpetiole node rounded in profile; in dorsal view much broader than petiole node. Sculpture and pilosity of both nodes similar to those of mesosomal dorsum.
Gaster in dorsal view 2.01-2.29 times wider than postpetiole; slightly shiny and first tergum wholly finely reticulate and with sparse yellowish, slender suberect to erect setae.
Color of body yellowish to light orange, gaster and appendages slightly lighter. Gyne and male unknown.  Etymology. Named for the Morongo, a band of the Cahuilla people who occupied occupied the northern part of this species range, in what is now Joshua Tree National Park. The name is a noun in apposition.
Remarks. In the keys of Creighton (1950) and Mackay (2000) T. morongo will run to T. silvestrii (Santschi 1911), an arboreal species from Arizona, which it resembles. In T. silvestrii the sculpture of the head and mesosoma is coarser, the head is proportionately a little broader, the propodeal spines are much shorter and the metafemora are much more robust, about three times longer than thick in dorsal view (also see Creighton 1953).
All known collections of this species are from pitfall traps, suggesting that this is a ground-nesting ant. Head longer than broad in frontal view, widest anterior to eyes; posterior to eyes evenly narrowed toward slightly convex posterior margin. Antenna 12-segmented; scape exceeding posterior margin by more than its apical width; 3-segmented apical club poorly defined. Eyes with scattered very short setae arising between ommatidia; IOD 2.34-2.60 × EL; EL 0.96-1.15 × OMD. Mandibles coarsely longitudinally rugose. Clypeus with strong median carina and without flanking carinae between it and carina defining median lobe; lateral lobes each with several short longitudinal carinae. Malar area with several irregular coarse longitudinal rugae, some of which extend back mesad of eyes to posterolateral corners; others curve mesad over antennal fossa; interspaces shiny and weakly reticulate; frons and vertex shiny between fine sparse piligerous punctures. Dorsum with numerous long standing setae, longest exceeding one-half minimum eye diameter, setae slender and not appreciably flattened; venter with several shorter setae on each side.
Mesosoma slender, WL 2.07-2.17 × PW; in profile, dorsum sloping from pronotum to base of propodeal spines; propodeal spines about as long as distance between their bases. Mesosoma moderately shiny and weakly sculptured between coarse irregular longitudinal rugae; posterior face of propodeum with weak transverse rugae. Metafemur 4.77-5.15 times longer than wide in dorsal view. Entire length of dorsum with >40 long fully erect setae similar to those of frons, longest subequal to minimum eye diameter.
Petiole with short anterior peduncle; node thick-triangular in profile, posteriorly gently curved; subpetiolar tooth short, acute. Postpetiole node high and subrectangular in profile. Postpetiole node 1.28-1.40 times as wide as petiole node. Both nodes longitudinally rugose, petiole node with weakly reticulate interspaces at side, postpetiole weakly reticulate throughout. Setae on nodes numerous and similar to those of mesosomal dorsum.
Gaster in dorsal view 3.34-4.15 times wider than node of postpetiole; disc of first tergite moderately shiny and very finely reticulate throughout, between sparse fine piligerous punctures. Segments with numerous suberect setae similar to those of mesosoma.
Dark brown, gaster darker posteriorly. Gyne and male unknown. Etymology. The name is derived from the superficial resemblance to species of the unrelated genus Myrmica.
Remarks. The large size, depressed mesosomal profile and long scapes will separate this from all other western Temnothorax. These features are shared with T. paiute, as is the presence of short setae on the eyes. The two differ, however, in the much more conspicuously and coarsely sculptured head and mesosoma of T. myrmiciformis (compare Figures 10 and 13).
The type series specimens were all collected in pitfall traps in grassy areas in oak woodland. The species has otherwise been collected in coastal sage scrub, chaparral, and Sonoran desert. The specimen collected by Creighton was taken near the beach at Bahia San Quintín, under a clump of Mesembryanthemum.
Head longer than broad in frontal view, lateral margins very weakly convex, posterior margin flat to very weakly convex. Antennal scape just outreaching posterior margin; apical club distinctly 3-segmented. IOD 2.53-3.02 × EL; EL 0.99-1.27 × OMD. Mandible finely longitudinally rugose. Clypeus with 1 or 2 short fine carinae on either side of median carina. Dorsum of head with irregular longitudinal rugae, interspaces from mostly smooth between rugae along dorsum midline to contiguously reticulate laterally; malar area with several short fine longitudinal rugae, interspaces dull and sharply reticulate; posterolateral angles of head moderately shiny and weakly reticulate. Dorsum of head with relatively dense, blunt setae.
Mesosoma slender, WL 1.78-2.11 times longer than PW; mesosomal dorsum weakly convex in profile, sloping down to sharp propodeal spines. Mesosomal dorsum moderately rugose with corrugated interspaces and the corrugation faintest medially on pronotum; side of pronotum coarsely rugose, interspaces inconsistently corrugated; posterior face of propodeum dull and reticulate. Metafemur 4.26-5.38 times longer than wide in dorsal view. Entire length of dorsum with 20+ blunt setae that are distinctly longer than those of frons.
Petiole with only very short anterior peduncle; node robust and subtriangular, no higher than thick, summit flattened; subpetiolar tooth short and acute. Postpetiole profile low; in dorsal view node 1.54-1.76 times width of petiole node. Petiole coarsely rugose laterally and dorsally with interspaces corrugated and anterior face reticulate; postpetiole with much weaker rugosity laterally and posteriorly, with semi-regular corrugation transitioning to fading reticulum dorsally; dorsum of postpetiole can be relatively smooth, but traces of reticulum can be seen in most specimens. Petiole with 6-8 setae similar to those of mesosoma and postpetiole with 14-16 setae.
Gaster in dorsal view 1.93-2.36 times wider than postpetiole node; surface of first tergite smooth and shiny between sparse piligerous punctures; surface with sparse suberect flattened setae similar to those of mesosoma and scattered finer prostrate pubescence.
Head and body dark brown. Gyne unknown.  postpetiole more than 1.5 × as wide as long in dorsal view will serve to distinguish this species from other Temnothorax occurring in the area. With regard to color and sculpture, T. nuwuvi is similar to T. nevadensis. The latter is a very variable species, but the combination of less robust petiolar node, postpetiole relatively more narrow, and longer propodeal spines in T. nevadensis  in nevadensis vs.  in nuwuvi) (Figures 11B,21D) will serve to distinguish the two.

Diagnosis of worker.
Mesonotum distinctly sloping down to metanotal area and base of propodeum slightly convex; first gastral tergum slightly shiny and very finely sculptured throughout; side of head behind eyes with no more than 1 or 2 short fine setae. Head longer than broad in frontal view; posterior margin transverse and lateral margins essentially parallel. Antenna 12-segmented; scape long and exceeding posterior margin by more than its apical width; antennal club distinct, 3-segmented. Eye large and moderately bulging, IOD about 2.54-2.71 × EL; with a few widely scattered very short setae arising between ommatidia; EL 0.98-1.17 × OMD. Mandibles coarsely longitudinally rugose. Head slightly shiny and conspicuously finely reticulate and with widely scattered obscure minute punctures; interrugal surfaces of clypeus smooth and shiny; malar area with several short obscure rugulae. Sparse short yellowish erect to suberect setae on front of head; more abundant suberect to erect setae on hypostomal area.
Mesosoma slender, WL 2.08-2.19 times longer than PW; in profile, posterior portion of mesonotum sloping down to metanotal impression, behind which dorsal face of propodeum is slightly raised and weakly convex. Propodeal spines present and well-developed: PSI 15.1-16.9; stout and shorter than infraspinal distance in largest specimens (California), more slender and longer than infraspinal distance in smaller (Nevada) specimens. Entire pronotum and mesosomal dorsum slightly shiny and finely reticulate, without rugae; mesepisternum and side of propodeum with conspicuous more or less longitudinal rugae, metapleural suture with about 6 coarse cross-rugae. Metafemur slender, 4.29-4.93 times longer than wide in dorsal view. Dorsum, including propodeum, with sparse yellowish slender erect setae.
Petiole node high in profile, summit broadly rounded; acute subpetiolar tooth present; summit of postpetiole rounded in profile; in dorsal view quadrate to slightly trapezoidal. Both nodes slightly shiny and finely reticulate, without rugae and with sparse yellowish slender erect setae.
Gaster, in dorsal view, 3.12-3.54 times broader than width of postpetiole; slightly shiny and first tergum finely reticulate throughout; sparse yellowish slender erect setae evenly distributed on first tergum; first tergum also with widely scattered finer subappressed setae.
Color of body medium brown with gaster darker. Gyne and male unknown. Etymology. This species is named for the peoples of the Paiute Nation and is to be treated as a noun in apposition.
Remarks. The two specimens from Nevada have proportionately slightly longer scapes than those of the Lone Pine specimens ), but otherwise share the unique features cited in the diagnosis. Although T. paiute unquestionably belongs among the species placed in the former subgenus Myrafant, characterized within our fauna by the presence of a median longitudinal clypeal carina and the absence of the metanotal suture across the dorsum, it does not appear to belong to any of the previously recognized species groups. Also see above under T. myrmiciformis.
Diagnosis of worker. Mesosoma, petiole and postpetiole dull and contiguously punctate; head shinier, punctures larger, shallower and distinctly shiny within, without fine rugae except above frontal lobes and around antennal fossa; subpetiolar process short and broad. Head longer than broad in frontal view; posterior margin mostly transverse but with small median impression; lateral margins very weakly convex and slightly convergent behind eyes. Antenna 12-segmented; scape short of posterior margin by slightly more than its apical width; apical club distinctly 3-segmented. Eye small and slightly bulging in frontal view; IOD 2.77-3.22 × EL; EL 0.89-1.05 × OMD. Most of head slightly shiny, with reticulation shiny within; midline of frons shinier, less strongly sculptured and with indistinct median smooth line; very fine rugae curving around antennal fossa; additional very fine rugae extending back from frontal lobes but ending well below vertex; median and submedian clypeal carinae weak. Dorsum of head with scattered very short to short (one vertex) flattened yellowish setae.
Mesosoma slender, WL 2.03-2.17 × PW in dorsal view; dorsal profile slightly convex. Propodeal spines short and acute, about half as long as distance between their bases. Entire mesosoma dull and reticulate, without rugulae or reticulae. Metafemur 3.93-4.69 times as long as wide in dorsal view. Dorsum with 16-18 short erect flattened yellowish setae.
Petiole node blunt and rounded in profile; subpetiolar process short and obtuse in profile; postpetiole node low and broadly rounded. Sculpture of both nodes similar to that of mesosoma.
Gaster in dorsal view about 2.87-3.28 times wider than postpetiole; first tergum smooth and shiny between scattered fine piligerous punctures; setae short and flattened.
Head and body uniformly pale yellow reddish yellow; gaster slightly darker or no darker. Gyne: measurements (    Etymology. From Greek, pseudos (false) + andrei, for the close resemblance of this species to T. andrei.
Remarks. As the name suggests, T. pseudandrei is similar to, and may be confused with, T. andrei, a common ground-dwelling species in California and neighboring states. Workers of T. pseudandrei differ by the short, broad subpetiolar process and the less robust, more acute petiolar node (Figures 20B, 21A). The worker of T. pseudandrei lacks erect setae on the underside of the head and the gyne has a single pair of very short flattened setae a short distance behind the oral cavity. Fine erect setae are present on the underside of the head in both workers and gynes of T. andrei. Additionally, the erect setae on the cephalic and mesosomal dorsa are shorter and less numerous.
Males of the two species are similar but differ in the length of the few setae present on the upper frons and vertex. In T. andrei there are about 10 setae, including 2 along the lateral margins and all are distinctly longer than the maximum diameter of the anterior ocellus. A few setae are also present on the underside of the head. Males of T. pseudandrei have about 6 setae on the vertex, none on the frons none along the lateral margins and none on the underside of the head. Those setae present on the vertex are only slightly longer than the greatest diameter of the anterior ocellus.
Little is known of the ecology of this ant other than that it is an arboreal species. As noted above, the Bard specimens were taken from under the bark of desert willow (Chilopsis linearis) in habitat that is now a much fragmented riverine gallery forest. The habitat for the Arizona specimens is similar, but in this instance the specimens were nesting in the bark of Fremont cottonwood (Populus fremontii). No data are available for the Resting Springs specimens and they were presumably taken at lights at night. That habitat is not riverine, but originally there was a flowing spring and a substantial stand of Fremont cottonwood. The site has been commercially developed and most of the cottonwood trees are no longer there. N/A; PTW 0.193;PW 0.298;SL 0.339;WL 0.587. Indices: CI 78.6;FI 80.3;OI 17.0;PI 130; PSI N/A; SI 64.1.
Head longer than broad in frontal view; posterior margin transverse and weakly concave in middle; lateral margins weakly curved and slightly convergent toward mandibular bases. Antenna 12-segmented; scape short and ending well below posterior margin; apical club distinctly three-segmented. Eye small, IOD 4.04 × EL; EL 0.73 times OMD. Mandible moderately coarsely rugulose (rugulae finer than in T. andrei Emery). Head moderately shiny and with narrow shiny median line; surface mostly very finely lineolate ("striate") and with dense (especially anteriorly) minute shallow punctures becoming sparser and less distinct posteriorly and with scattered coarser piligerous punctures; antennal fossa and malar area only slightly shiny and roughened between well-separated fine rugulae (straight on malar area, curving mesad over fossa). Dorsum of head with widely scattered short, erect to suberect yellowish setae, the setae stiff and slightly flattened; similar but longer setae beneath.
Mesosoma stout, WL 1.97 times PW; mesosomal profile deep, distance from dorsal mesonotal margin to base of mesocoxa 0.50 times WL; mesosomal dorsum distinctly convex in profile. Propodeal spines reduced to blunt obtuse angles in profile. Mesosoma opaque and reticulate, except infraspinal face of propodeum less strongly sculptured and shinier. Dorsum with about 20 sparse slightly flattened yellowish setae that are longer than those of head. Metafemur robust, 3.27 times longer than wide in dorsal view.
Petiole lacking anterior peduncle; node robustly triangular in profile with rounded summit; subpetiolar process consisting of a distinct thin flange that is acute anteriorly. Postpetiolar node profile high and rounded and in dorsal view trapezoidal with pronounced anterior corners and 1.30 times width of petiolar node. Sculpture and pilosity of both nodes similar to those of mesosoma.
Gaster in dorsal view 2.26 times wider than node of postpetiole; disc of first tergum smooth and shiny with scattered minute piligerous punctures; setae fine and yellowish, slightly flattened; remaining segments with similar setae.
Etymology. Temnothorax quasimodo is named for the Victor Hugo character in his novel The Hunchback of Notre Dame.
Remarks. The short, deep mesosoma with distinctly convex dorsum results in a "hunched" profile that is characteristic for this species. This profile is similar to that of some species placed in the erstwhile subgenus Macromischa Roger (1863).
Superficially this species resembles T. andrei, a species that is common in similar habitat and was collected in the same litter sample as T. quasimodo (P. S. Ward, pers. comm.). The distinctive mesosomal profile of T. quasimodo will readily distinguish between the two (Figures 17, 21A). The unusual form of both the mesosoma and broadening of postpetiole may indicate that this is a socially parasitic or inquilinous species (Wilson 1984), perhaps in nests of such other species as T. andrei.
We did not observe similar morphological modifications among multiple nest series and hundreds of specimens of T. andrei examined during this study. T. quasimodo was found in a locality where intensive sampling has been carried out, mostly by Philip S. Ward (pers. comm.) and UC Davis entomology students, but the species has been collected only once. We conclude that it represents an extremely infrequently encountered species such as Lasius atopus (Cole, 1958a) or Stigmatomma trigonignathum (Brown, 1949), although until more material is collected we cannot be certain that the holotype is not a result of a rare environmentally induced malformation.
Temnothorax rudis (Wheeler, 1917)  Head longer than broad, margins subparallel, broadly rounded into transverse posterior margin. Antenna 12-segmented and scape extending slightly beyond posterior margin of head; three-segmented apical club poorly defined. Eyes moderately convex and without short setae arising from between ommatidia; IOD 2.77-2.90 × EL; EL 0.96-1.01 × OMD. Medial carina of clypeus sharply defined, as are 2-3 short carinae on either side. Malar area with several well-spaced longitudinal rugae that curve mesad of eye to slightly behind level of upper eye margin; similar rugae curve mesad above antennal fossae. Frons and vertex moderately shiny and reticulate and with scattered poorly defined longitudinal rugae. Dorsum with numerous short, fully erect, slightly flattened setae, but none along margins of head in frontal view; venter with sparse, finer setae about as long as those of frons.
Mesosoma slender, WL 2.19-2.29 × PW; dorsal profile nearly flat from anterior edge of mesonotum to base of propodeal spines. Propodeal spines short and stout, less than half as long as distance between their bases. Pronotal dorsum and side coarsely cor- rugated/rugoreticulate; remainder of dorsum with variable degrees of corrugation and/ or irregular longitudinal rugae; interspaces moderately shiny and reticulate; mesepisternum and propodeum side with well-spaced, irregular coarse rugae and densely reticulate interspaces. Hind femur 4.31-4.65 times longer than wide in dorsal view. Dorsum with 15-20 fully erect flattened, blunt-tipped setae that are longer than those of frons.
Petiole node high and subacute in profile; subpetiolar process short and blunt; postpetiole node robust, high and broadly rounded in profile, about twice as wide as petiole node; Posterior face of petiole node coarsely areolate, postpetiole node contiguously punctate only. Gaster in dorsal view 1.83-2.41 times as wide as postpetiole node; first tergum smooth and shiny, with sparse piligerous punctures, the setae suberect, slightly flattened, and blunt-tipped.
Head and body light reddish brown, gaster darker. Gyne and male unknown.   Etymology. This species is dedicated to Phil Ward, who provided so much of the material utilized in this paper. Remarks. The combination of flat mesosomal dorsum, short and upward-directed propodeal spines with extremely swollen postpetiole will separate this species from all other western Temnothorax. In dorsal view the relatively closely spaced propodeal spines and the postpetiole, which is almost twice as wide as the petiole, are especially conspicuous. ; Figure 18A).
The known specimens have been collected in pitfall traps in chaparral and from nest middens of Forelius ants.

Key to California species of Temnothorax
Below we provide a worker-based key to the 20 species of Temnothorax known from California, plus two additional species (T. nuwuvi, T. carinatus) known from neighboring states to the east. In California, Temnothorax can be most easily confused with Leptothorax, Tetramorium and Myrmica, but all these genera have at least six mandibular teeth. Additionally, Tetramorium and Myrmica possess mid-and hind tibial spurs. In western North America, workers of Temnothorax can be recognized by a combination of a waist consisting of two segments (petiole and postpetiole); postpetiole attached to anterior face of abdomi nal segment 4 (first gastral segment); absence of promesonotal suture from mesosoma; antennae 11-or 12-segmented and with differentiated 3-segmented club; eyes present and consisting of at least several facets; frontal carinae not laterally expanded or extending posteriorly past the eye; presence of median clypeal carina; clypeus elevated slightly above mandibles in profile view, not an anteriorly projecting lobe that fits tightly over the base of the mandibles; mandibles with five teeth; propodeal spines present at least as distinct tubercles and tibial spurs on middle and hind legs absent. A user-friendly key to ant genera of North America is available in Fisher and Cover (2007).