Formicidae

Ward, P. S., 2005, A synoptic review of the ants of California (Hymenoptera: Formicidae)., Zootaxa 936, pp. 1-68 : 20-25

publication ID

https://doi.org/10.5281/zenodo.6268077

publication LSID

lsid:zoobank.org:pub:DEBCE6E9-17D9-43A3-814B-0C3431DEBF4A

DOI

https://doi.org/10.5281/zenodo.6268077

persistent identifier

https://treatment.plazi.org/id/210D5803-3815-8C5F-0DFB-75E6A02945DE

treatment provided by

Thomas

scientific name

Formicidae
status

 

KEY TO CALIFORNIA ANT GENERA BASED ON THE WORKER CASTE [[ Formicidae ]]

Morphological terminology follows Bolton (1994), on which much of this key is based. The term mesosoma is used in preference to alitrunk, to refer to the body part formed from fusion of the thorax and the first abdominal segment (i.e., thorax + propodeum). The promesonotum is that part of the mesosoma composed of the pronotum and the mesonotum. Metasoma refers to the apparent abdomen, comprising the segments posterior to the propodeum, i.e., abdominal segment 2 and succeeding segments. In ants abdominal segment2 forms a node- or scale-like petiole, which is separated by a constriction from the rest of the metasoma. In some species abdominal segment 3 is also node-like and in this case it is said to form a postpetiole.

The key has been designed to apply only to those ant species occurring in California but it should also work for most of western North America, excluding Arizona and New Mexico where additional genera occur.

1 Postpetiole present: abdominal segment 3 separated from segment 4 by a strong constriction and distinctly smaller in size, so that anteriorly the metasoma has two nodelike segments, the petiole and postpetiole .................................................................... 2

- Postpetiole absent: abdominal segment 3 separated from segment 4 by a weak to moderate constriction or by none at all, and when viewed in profile not distinctly smaller in size (height) than segment 4; metasoma anteriorly with a single, isolated node-like or scale-like segment ....................................................................................................... 26

2 Eye reduced to a single ommatidium or absent; antennal insertions fully exposed in a full-face view of head ( Ecitoninae   HNS ) ........................................ Neivamyrmex Borgmeier   HNS

- Eye very rarely reduced, usually consisting of multiple ommatidia; antennal insertions not fully exposed, covered partially by frontal lobes or medial extensions of the antennal sclerites, when the head is observed in full-face view ........................................... 3

3 Eye very large, eye length about one-half of head length (excluding mandibles); pronotum freely articulating with mesonotum ( Pseudomyrmecinae   HNS ) ............................. ....................................................................................................... Pseudomyrmex Lund   HNS

- Eye less than one-half head length; pronotum fused with mesonotum ( Myrmicinae   HNS ) ... ....................................................................................................................................... 4

4 Antenna with 6 segments, including a 2-segmented club ............................................. 5

- Antenna with 10 segments, including a 2-segmented club ......... Solenopsis Westwood   HNS

- Antenna with 11 segments; club variable ..................................................................... 6

- Antenna with 12 segments; club variable.. ................................................................ 14

5 Mandible elongate and linear, with an apical fork of two spiniform teeth ...................... ...................................................................................................... Strumigenys F. Smith   HNS

- Mandible short and subtriangular, with a multi-denticulate masticatory margin ........... ............................................................................................................... Pyramica Roger   HNS

6 Postpetiole attached to the dorsal surface of the following abdominal segment; petiole dorsoventrally flattened, not node-like in profile ........................... Crematogaster Mayr   HNS

- Postpetiole attached to the anterior face of the following segment; petiole node-like in profile, not dorsoventrally flattened ............................................................................. 7

7 Head in lateral view with a diagonal carina running from above the eye down toward the mandibular insertion; promesonotum with conspicuous tubercles or spines ......... 8

- Head in lateral view lacking such a diagonal carina; promesonotum without conspicuous tubercles or spines .................................................................................................9

8 Frontal lobes expanded laterally and covering the sides of the head below the eyes, in full-face view; body lacking erect pilosity.................................... Cyphomyrmex Mayr   HNS

- Frontal lobes not expanded laterally to cover the sides of the head; body with erect pilosity.............................................................................................. Acromyrmex Mayr   HNS

9 Antenna with a distinct 2-segmented apical club............................... Wasmannia Forel   HNS

- Antenna lacking a distinct 2-segmented apical club, either 3-segmented or indistinct.. .....................................................................................................................................10

10 Eye absent or rudimentary; propodeum unarmed, basal face rounding into declivitous face ................................................................................................ Solenopsidini   HNS new genus

- Eye well developed, with multiple ommatidia; propodeum angulate or spinose.......11

11 Lateral portions of clypeus, in front of the antennal insertions, developed in the form of a raised ridge or shield-wall; frontal carinae extending almost to the posterior margin of the head......................................................................... Tetramorium Mayr   HNS (part)

- Lateral portions of clypeus not developed as a raised ridge or shield-wall; frontal carinae very short or absent...............................................................................................12

12 Eye with short erect setae projecting between the ommatidia........ Formicoxenus Mayr   HNS

- Eye lacking erect setae................................................................................................13

13 Median portion of clypeus with a smooth, longitudinally excavate surface, and lacking carinae .............................................................................................. Leptothorax Mayr   HNS

- Median portion of clypeus with several longitudinal carinae......................................... ................................................................................................. Temnothorax Mayr   HNS (part)

14 Hind tibial spur finely pectinate (as seen at 50-100x magnification).........................15

- Hind tibial spur simple or absent.................................................................................17

15 Metanotal groove absent or very weakly impressed, not breaking the dorsal profile of the mesosoma; psammophore usually present............................ Pogonomyrmex Mayr   HNS

- Metanotal groove present and interrupting the dorsal profile of the mesosoma; psammophore absent...........................................................................................................16

16 Propodeum unarmed; mandible with more than 12 teeth ....................... Manica Jurine   HNS

- Propodeum armed with a pair of spines; mandible with 6-10 teeth .. Myrmica Latreille   HNS

17 Lateral portions of clypeus, in front of the antennal insertions, developed in the form of a raised ridge or shield-wall; apex of sting with triangular lamellate appendage...... ................................................................................................. Tetramorium Mayr   HNS (part)

- Lateral portions of clypeus not developed as a raised ridge or shield-wall; apex of sting without triangular lamellate appendage .....................................................................18

18 Petiole short and sessile, lacking well differentiated anterior peduncle and dorsal node; ventrolateral margin of head with sharp, longitudinal carina extending from mandibular base to posterolateral corner of head........................................... Myrmecina Curtis   HNS

- Petiole with anterior peduncle and dorsal node; ventrolateral margin of head without sharp, longitudinal carina ...........................................................................................19

19 Dorsum of head and mesosoma without standing pilosity .......... Cardiocondyla Emery   HNS

- Dorsum of head and mesosoma with standing pilosity ............................................... 20

20 Anteromedian portion of clypeus notably elevated and bounded by a pair of carinae that diverge anteriorly ................................................................................................ 21

- Anteromedian portion of clypeus not abruptly elevated and lacking a pair of anteriorly diverging carinae ........................................................................................................ 23

21 Propodeum unarmed ....................................................................... Monomorium Mayr   HNS

- Propodeum armed with a pair of teeth or spines ........................................................ 22

22 Antennal club 3-segmented; propodeal spiracle large and located close to the declivitous face of the propodeum, separated from latter by no more than the diameter of the spiracle .................................................................................................. Rogeria Emery   HNS

- Antennal club 4-segmented; propodeal spiracle relatively small and separated from the declivitous face of the propodeum by more than the spiracle diameter .......................... ....................................................................................................... Stenamma Westwood   HNS

23 Antennal club 3- (rarely 4-) segmented ....................................................................... 24

- Antenna lacking a distinct club ................................................................................... 25

24 In profile promesonotum domed and distinctly elevated above the propodeal dorsum; workers dimorphic ......................................................................... Pheidole Westwood   HNS

- In profile entire mesosoma dorsum flat to weakly convex, promesonotum not domed or markedly elevated above the level of the propodeum; workers monomorphic .......... ................................................................................................. Temnothorax Mayr   HNS (part)

25 Head narrow, longer than broad; mandible slender and triangular, outer margin not strongly curving towards the midline; psammophore absent ...... Aphaenogaster Mayr   HNS

- Head broad, subquadrate; mandible short and thick, outer margin strongly curving towards the midline; psammophore usually present ................................. Messor Forel   HNS

26 Pygidium (last visible abdominal tergite) flattened and bordered laterally with a row of peg-like teeth or spines that converge distally ( Cerapachyinae   HNS ).... Cerapachys F. Smith   HNS

- Pygidium (last visible abdominal tergite) convex and rounded, lacking a row of teeth or spines ..................................................................................................................... 27

27 Distinct constriction between abdominal segments 3 and 4; terga and sterna of abdominal segments 3 and 4 laterally fused ......................................................................... 28

- No constriction between abdominal segments 3 and 4; terga of abdominal segments 3 and 4 overlapping the corresponding sterna, not laterally fused with them ............... 30

28 Articulation of petiole (second abdominal segment) to third abdominal segment very broad; petiole without a distinct posterior face ( Amblyoponinae   HNS ) .................................. ..................................................................................................... Amblyopone Erichson   HNS

- Articulation of petiole (second abdominal segment) to third abdominal segment narrow; petiole with a distinct posterior face .................................................................. 29

29 Pronotum freely articulating with the mesonotum; abdominal tergite 4 not strongly enlarged and not curved ventrally; apex of metasoma directed posteriorly ( Ponerinae   HNS ) ....................................................................................................... Hypoponera Santschi   HNS

- Pronotum fused immovably to the mesonotum; abdominal tergite 4 strongly enlarged and curved ventrally; apex of metasoma directed anteriorly ( Proceratiinae   HNS ).................. .......................................................................................................... Proceratium Roger   HNS

30 Apex of metasoma with a circular orifice, often fringed with short setae (the acidopore) ( Formicinae   HNS )...................................................................................................31

- Apex of metasoma with a slit-shaped orifice ( Dolichoderinae   HNS )..................................38

31 Antenna with 9 segments ............................................................. Brachymyrmex Mayr   HNS

- Antenna with 11 segments ................................................................. Plagiolepis Mayr   HNS

- Antenna with 12 segments .........................................................................................32

32 Metapleural gland absent; antennal insertions well separated from the posterior clypeal margin; in profile mesosoma dorsum usually evenly convex........................ Camponotus Mayr   HNS

- Metapleural gland present; antennal insertions adjacent to the posterior clypeal margin; in profile promesonotum separated from the dorsal face of the propodeum by a distinct impression .....................................................................................................33

33 Maxillary palp segments 3 and 4 greatly elongated, segment 3 (counting from base) half the head length or more; psammophore present.............. Myrmecocystus Wesmael   HNS

- Maxillary palp segments 3 and 4 not greatly elongated, segment 3 much less than half the head length; psammophore absent .......................................................................34

34 Ocelli present; propodeal spiracle elliptical to oval....................................................35

- Ocelli absent or indistinct; propodeal spiracle circular to subcircular.......................36

35 Mandible triangular, with seven or more distinct teeth on the masticatory margin........ ............................................................................................................ Formica Linnaeus   HNS

- Mandible falcate (sickle-shaped) and lacking distinct teeth............ Polyergus Latreille   HNS

36 Dorsum of head and mesosoma with coarse setae, arranged in distinct pairs; eye situated in relatively anterior position, at or in front of midlength of side of head ............. ............................................................................................ Paratrechina Motschoulsky   HNS

- Pilosity on dorsum of head and mesosoma variable, but not arranged as coarse setae in pairs; eye situated in relatively posterior position, behind midlength of side of head ... .....................................................................................................................................37

37 Mandible with six teeth; antennal scape long, surpassing posterior margin of head by more than half its length; mesonotum in dorsal view strongly constricted behind pronotum .............................................................................................................. Prenolepis Mayr   HNS

- Mandible with seven or more teeth; antennal scape shorter, surpassing posterior margin of head by less than a third its length; mesonotum in dorsal view not strongly constricted behind pronotum...................................................................... Lasius Fabricius   HNS

38 Propodeum with a prominent conical tooth at the junction of the dorsal and declivitous faces; maxillary palp segment 3 elongate, subequal in length to segments 4-6; apical mandibular tooth much enlarged...................................................... Dorymyrmex Mayr   HNS

- Propodeum rounded or subangulate at the junction of the dorsal and declivitous faces, but without a conical tooth; maxillary palp segment 3 short, subequal in length to segments4; apical mandibular tooth not notably enlarged .............................................. 39

39 Mesosoma dorsum lacking standing pilosity .............................................................. 40

- Mesosoma dorsum with standing pilosity .................................................................. 41

40 Petiole flattened, plate-like, and without a conspicuous, dorsally protruding scale (petiole often overhung by the succeeding abdominal segment); dorsal face of propodeum much shorter than the declivitous (posterior) face ............................ Tapinoma Foerster   HNS

- Petiole with a well developed, dorsally protruding scale; dorsal face of propodeum subequal in length to declivitous face .............................................. Linepithema Mayr   HNS

41 In profile mesosoma dorsum without an impressed metanotal groove, the promesonotum and propodeum forming a continuous surface; workers variable in size within a colony ........................................................................................................... Liometopum Mayr   HNS

- In profile mesosoma dorsum interrupted by a well marked metanotal groove; workers showing little intra-colony size variation .................................................................... 42

42 Petiole lacking an erect scale; side of mesosoma with conspicuous microreticulate sculpture; dark brown-black, with contrastingly paler tarsi .......... Technomyrmex Mayr   HNS

- Petiole with well developed erect scale; side of mesosoma without conspicuous microreticulate sculpture; varying in color from yellowish-orange to dark brown, but without contrastingly paler tarsi ............................................................ Forelius Emery   HNS

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Hymenoptera

Family

Formicidae