Temnothorax, Mayr, 1861

Schifani, Enrico, Prebus, Matthew M. & Alicata, Antonio, 2022, Integrating morphology with phylogenomics to describe four island endemic species of Temnothorax from Sicily and Malta (Hymenoptera, Formicidae), European Journal of Taxonomy 833 (1), pp. 143-179 : 171-172

Worker-based key to the Sicilian species of Temnothorax with light-colored pigmentation and concolorous antennal clubs

Note that recently emerged workers and queens of dark species (e.g., T. exilis ) may temporarily present a yellowish pigmentation. The key is meant to be used for species in which the final pigmentation of females is naturally light-colored. High-quality images of all the species are available on AntWeb.org. Quantitative and qualitative morphological characters mentioned in the key are defined in the Material and methods section of this paper.

1. Antennal segments reduced to 11 ..................................................................................................... 2

– 12 antennal segments ........................................................................................................................ 3

2. Extreme development of the subpetiolar process, short spines .............social parasite species of the gordiagini group, of which only T. ravouxi (André, 1896) is confirmed for Sicily. However, the possible presence of T. kraussei (Emery, 1915) cannot be discarded, see Seifert (2018) for their differentiation

– Subpetiolar process falling within the variation described in the materials and methods of this study; free-living species .................................................................................. T. flavicornis ( Emery, 1870)

3. Long erect setae on the dorsum of the body; metanotal groove very deep; propodeal spines very short ...................................................................................................... T. recedens (Nylander, 1856)

– Setae shorter; metanotal groove absent or weak; if present, propodeal spines longer ..................... 4

4. Relatively large arboreal species; most of the body ferruginous; petiole bulky and short, unlike any other species of the key; propodeal spines long ........................................ T. clypeatus (Mayr, 1853)

– Character combination deviating from above ................................................................................... 5

5. Petiole narrow; metanotal groove present; head often darker than the mesosoma; subpetiolar process limited to a carina-like shape ................................... nylanderi group (also see Csősz et al. 2015) 6

– Character combination deviating from above ................................................................................... 7

6. Propodeal spines very long, deviating very little from the mesosoma axis (20–25°); more thermophilous ................................................................................. T. lichtensteini (Bondroit, 1918)

– Propodeal spines shorter, deviating more from the mesosoma axis; usually higher altitude sites ..... ............................................................................................................... T. nylanderi (Foerster, 1850)

7. Color ferruginous; sculpture striate, particularly strong in larger individuals; frons with a shiny area; propodeal spines long; size large (normally CS> 600) ...................................................................... ....................................................................................... T. poldii Alicata, Schifani & Prebus sp. nov.

– Color yellowish, sculpture weaker, size normally smaller (CS <600) ............................................ 8

8. Propodeal spines long; subpetiolar process tooth-like .................. T. lagrecai ( Baroni Urbani, 1964)

– Propodeal spines short; subpetiolar process with a carina-like form ............................................... 9

9. Upper profile of petiole rather blunt, forming a weakly delimited horizontal plane; SE Sicily ......... ...................................................................................... T. marae Alicata, Schifani & Prebus sp. nov.

– Upper profile of petiole very sharp, usually not forming an horizontal plane; NW Sicily ................. ................................................................................... T. vivianoi Schifani, Alicata & Prebus sp. nov.

UCE sequence processing and phylogenomic inference

Following assembly and UCE extraction, the mean number of loci per specimen was 2242, with a mean contig length of 885 bp, and a mean coverage score of 44.3x (see Supp. file 1: Table S2). Following alignment, trimming and filtering of the full UCE dataset to loci with ≥85% taxon presence, the dataset had 2039 loci, with a mean locus alignment length of 793 bp. The concatenated matrix was 1 617 690 bp in length, in which 819 040 sites (50.6%) were variable, 533 245 sites (33%) were parsimony informative, with 19% missing data.

The partitioning analysis of the dataset resulted in a 260-partition scheme (see Dryad data repository; https://doi.org/10.25338/B8K63Z). The tree resulting from the IQTREE analysis ( Fig. 80 ) had strong overall maximum likelihood bootstrap support. The phylogenetic placements of the species described in the current study, all of which fell within the subclade ‘Palearctic clade IV’ (sensu Prebus 2017), were unambiguous with respect to their closest relatives. As a side note, ‘Palearctic clade II’ (sensu Prebus 2017), which was composed of taxa from eastern and southern Asia, was recovered as paraphyletic in the current study. It now appears to consist of two clades, which are renamed ‘Palearctic clade IIa’ and ‘Palearctic clade IIb’ (see Fig. 79 ).

Figures

Figs 80–81. Geographic distribution of the four taxa treated in this study. Note that the shallow water area (light grey) between Sicily and the Maltese Islands roughly corresponded to a land bridge during glaciations.

Fig. 79. Maximum likelihood phylogeny inferred with IQTREE ver. 2.1.2. The major clades found in Prebus (2017) are highlighted, and the focal species of the current study (all within the ‘Palearctic clade IV’) are evidenced as in Figs 75–78. Maximum likelihood bootstrap support for all nodes are 100, except where indicated.