Temnothorax salvini clade

based on Prebus 2017

Introduction
Prebus (2017) provided evidence for the Nearctic origin of the crown Temnothorax, followed by a rapid radiation across the majority of the present-day range. The initial radiation resolved into seven large clades, including several lineages that dispersed to the Neotropics soon after the origin of the crown group. Among these early-arriving Neotropical lineages is the morphologically heterogenous salvini clade. More information about the clades can be found in Prebus, 2017 and here: Temnothorax clades.

Diagnosis
Based on the worker caste, the T. salvini clade lack a singular diagnostic feature, but can be diagnosed with the following combination of characters:
 * 1) Antennae composed of 12 antennomeres.
 * 2) Postpetiole moderately to very broad: 1.4 to 3 times as broad as the caudal cylinder in dorsal view (PWI 140-300); if less than 1.5 times, then antennal scapes are moderately short, failing to reach the posterior margin of the head by the maximum width of the antennal scape or less, and dorsum of propodeum lacks standing setae.
 * 3) Anterodorsal region of petiole with or without tubercles that are united by a transverse carina; if tubercles present, then median lobe of clypeus bearing many (> 3) fine carinae, femora incrassate (FI> 250), or, if femora not incrassate, then dorsum of propodeum lacks standing setae.
 * 4) Propodeum bearing teeth or spines; or, if propodeum is unarmed, then propodeum is strongly depressed below the level of the evenly convex promesonotum.
 * 5) Legs usually without long tapering setae, but if present, then medial lobe of clypeus bearing many (> 3) longitudinal carinae, or propodeum is strongly depressed below the level of the evenly convex promesonotum.

Identification
Key to Temnothorax clades

Key to Temnothorax salvini clade workers

Species
The clade is are organized into species group, which are used here correspond to morphologically-diagnosable groups of species which are supported as monophyletic groups by molecular evidence (Prebus 2017, 2020, and unpublished work that will be included in publications being prepared for publication.)

acuminatus group
This group is composed of two previously undescribed species, T. acuminatus and T. tuxtlanus. They occur in the southern Mexican mountains of Los Tuxtlas and the Sierra Madre de Chiapas at mid-to-high elevations. These species are united by the lack of setae on the dorsum of the propodeum, reduced subpetiolar tooth, moderately impressed metanotal groove, posterodorsally directed propodeal spines, and dark coloration. The two species of this group have been collected from bark crevices, under epiphyte mats on treefalls, and sifted leaf litter.

Species of the acuminatus group may be confused with T. acutispinosus, which has an overlapping distribution, similar habitus, and lack of setae on the propodeum. Temnothorax acutispinosus can be distinguished from the acuminatus group by the larger subpetiolar tooth and dorsally directed propodeal spines. The two species of the acuminatus group are sister to the remainder of the salvini clade (Prebus, in prep.).

acuminatus group species
 * Temnothorax acuminatus
 * Temnothorax tuxtlanus

acutispinosus group
This group is monotypic, with the nominal T. acutispinosus being the only member. It is morphologically similar to the members of the acuminatus group, with which it overlaps geographically, but differs from them by the larger subpetiolar tooth and dorsally directed propodeal spines. However, T. acutispinosus is apparently more closely related to the members of the rugosus  and annexus groups (Prebus, in prep.).


 * Temnothorax acutispinosus

altinodus group
This group is monotypic, with the nominal T. altinodus being the only member. It is morphologically similar to the members of the acuminatus and acutispinosus groups, sharing a lack of setae on the propodeal dorsum. It can be distinguished from these groups by the larger subpetiolar tooth (small in the acuminatus group) and the incrassate femora (not incrassate in the acuminatus and acutispinosus groups). Known from a single collection in the mid elevations of Honduras, this species is apparently sister to the fuscatus and pergandei groups (Prebus, in prep.).


 * Temnothorax altinodus

annexus group

 * Temnothorax annexus
 * Temnothorax arbustus
 * Temnothorax balnearius
 * Temnothorax obtusigaster
 * Temnothorax quercicola

augusti group

 * Temnothorax augusti
 * Temnothorax aureus
 * Temnothorax leucacanthoides
 * Temnothorax leucacanthus

casanovai group

 * Temnothorax casanovai

fuscatus group

 * Temnothorax fuscatus
 * Temnothorax nebliselva
 * Temnothorax ocarinae
 * Temnothorax skwarrae

goniops group

 * Temnothorax achii
 * Temnothorax goniops
 * Temnothorax huehuetenangoi
 * Temnothorax ixili
 * Temnothorax xincai

misomoschus group

 * Temnothorax misomoschus

pastinifer group

 * Temnothorax androsanus
 * Temnothorax nigricans
 * Temnothorax pastinifer
 * Temnothorax rutabulafer
 * Temnothorax schwarzi

pergandei group

 * Temnothorax bison
 * Temnothorax pergandei

pilicornis group
This group is monotypic, with the nominal T. pilicornis being the only member. Known only from coastal habitats and offshore islands of Baja California, this species has a generalized Temnothorax habitus, save for the extremely broad postpetiole. It can be separated from most similar appearing species be the combination of the broad postpetiole and erect setae on the antennal scapes.


 * Temnothorax pilicornis

pulchellus group
With fifteen species, the pulchellus group is the largest in the salvini clade. Primarily inhabiting low elevations on Caribbean islands and southern Florida, the group as a whole has a peculiar bimodal elevational distribution. Two species inhabit some of the highest points on the island of Hispaniola, but as of yet there are no mid-elevation collections for any species in the group. Nest collections, while rare, suggest nesting habits similar to the pastinifer group, i.e., within dead wood and vegetation on or near the ground, often in leaf litter.

The general habitus of the members of the pulchellus group is another example of the Macromischa syndrome, with most species having extremely arched mesosomata, often with enlarged femora, and always with broad postpetioles. These characters broadly overlap with the pastinifer group, T. subditivus, and some members of the sallei clade (e.g., the sallei and iris subclades sensu Prebus (2017)). Use the key to Temnothorax clades and key to T. salvini-clade workers, along with the ʻsimilar species' sections of each of the groups noted here, to find specific distinguishing characters.

pulchellus group species
 * Temnothorax agavicola
 * Temnothorax albispinus
 * Temnothorax bahoruco
 * Temnothorax balaclava
 * Temnothorax ciferrii
 * Temnothorax flavidulus
 * Temnothorax harlequina
 * Temnothorax hippolyta
 * Temnothorax laticrus
 * Temnothorax magnabulla
 * Temnothorax pulchellus
 * Temnothorax terricola
 * Temnothorax torrei
 * Temnothorax wettereri
 * Temnothorax wilsoni

rugosus group
This group is composed of two species, T. parralensis and T. rugosus, which are found at mid-to-high elevations in the southern United States to central Mexico. Members of this group have been collected from dead branches on live trees, mostly Quercus spp. The species of the rugosus group, with their arboreal nests, large size, coarse sculpturing, and somewhat incrassate femora, are very similar in habitus to the annexus group, but differ from them by their relatively short propodeal spines and shape of their petiolar nodes (cuneiform to truncate).

rugosus group species
 * Temnothorax parralensis
 * Temnothorax rugosus

salvini group
With ten species (eight described as new here), the salvini group is the second largest in the salvini clade. Up until a recent species delimitation study (Prebus, 2020), this group was thought to contain two species, T. aztecus and T. salvini, but upon including specimens from across its considerable geographic range and morphological variability, this group was found to contain an additional seven species. Following publication of this study, an additional species was discovered that had been overlooked in collections (T. terraztecus). The members of the salvini group inhabit all elevations throughout their range in southern Mexico and Central America, but individual species appear to have an affinity for nearly discrete elevational ranges when their geographic ranges overlap with other members of the salvini group. Prebus, 2020 illuminated some of the biogeographic history of the salvini group as well: it was inferred to have arisen in the northern part of its current range in habitats associated with contemporary mid-to-high elevations in the Miocene, approximately 13 Ma. Subsequently, the salvini group expanded into the southern Central American Cordilleras at the Miocene-Pliocene transition, coinciding with mountain building in that region 8-5 Ma, where today it is represented by T. salvini and T. longicaulis, Additionally, the salvini group expanded into low elevation habitats during the same transition period, with the widespread T. aztecus being the only member of the group inhabiting these habitats today. The nesting habits of the species of the salvini group, where they are known, are almost exclusively arboreal, nesting in vines, under epiphytes, or in dead vegetation suspended in the canopy. The one exception may be T. terraztecus, which has only been collected from leaf litter extractions from a couple of localities.

While the species within the salvini group can be difficult to tease apart morphologically, as a group they are quite distinctive, with long, tapering setae on all surfaces of the body, flat to slightly sinuate mesosomata in profile, and strongly sculptured head and mesosomata.

salvini group species
 * Temnothorax aztecoides
 * Temnothorax aztecus
 * Temnothorax fortispinosus
 * Temnothorax longinoi
 * Temnothorax longicaulis
 * Temnothorax paraztecus
 * Temnothorax parvidentatus
 * Temnothorax quetzal
 * Temnothorax salvini
 * Temnothorax terraztecus

subditivus group
This group is composed of two species, T. politus and T. subditivus. These species together have a vast range from the southern United States to northern South America, and can be found at all elevations. Nests are typically located in dead vegetation, under bark, or in the leaf litter. Finer details of the biology of this group remain unknown. All nest collections so far have been monogynous. The morphology of T. subditivus is extremely variable across its range and it may be a species-complex (more sampling and further study is needed).

As a species group, T. politus is easy to distinguish from other Nearctic Temnothorax, but the morphological characteristics and range of T. subditivus overlap broadly with the pulchellus group, the pastinifer group, and members of the sallei clade with characters of the Macromischa syndrome. The key to Temnothorax clades and key to T. salvini-clade workers, along with the ʻsimilar species' sections of each of the groups noted here, provide distinguishing characters that separate the two species of this group from lookalikes.

subditivus group species
 * Temnothorax politus
 * Temnothorax subditivus

tenuisculptus group
This group is monotypic, with the nominal T. tenuisculptus being the only member. The range of this species as we currently understand it is small, restricted to the low elevations of the Southern Sierra Madre and Los Tuxtlas in southern Mexico. It is morphologically similar to the members of the augusti group and is contained within its geographical range. Unlike the members of the augusti group, the petiolar node of T. tenuisculptus is erect, not leaning posteriorly. This species is sister to the annexus group (Prebus, in prep.).


 * Temnothorax tenuisculptus

terrigena group
This group is monotypic, with the nominal T. terrigena being the only member. The range of T. terrigena is small, restricted to the low elevations of the southern United States and northern Mexico. Apparently, this species is ground nesting. The generalized habitus of this ant has historically led to confusion about its relationships, but the moderately arched mesosoma dorsum and broad postpetiole are telltale signs of its membership in the salvini clade. Temnothorax terrigena may be confused with members of the andrei and sallei clades, and other members of the salvini clade (see the T. terrigena identification section for more details).


 * Temnothorax terrigena