Dtsch. Entomol. Z. 67 (2) 2020, 183-196 | DOI 10.3897/dez.67.53199 gee BERLIN Revision of the Plagiolepis schmitzii group with description of Pl. invadens sp. nov. — a new invasive supercolonial species (Hymenoptera: Formicidae) Bernhard Seifert! 1 Senckenberg Museum of Natural History Gorlitz, Am Museum 1, 02826 Gorlitz, Germany http://zoobank.org/A75EEE9F-F43B-4B56-BCF9-14CCB1238C64 Corresponding author: Bernhard Seifert (bernhard.seifert@senckenberg.de) Academic editor: D. Zimmermann @ Received 13 April 2020 # Accepted 3 August 2020 Published 21 September 2020 Abstract Using high-resolution stereomicroscopy and exploratory data analyses, a taxonomic revision of the cryptic species close to Plagi- olepis schmitzii Forel, 1895, called Pl. schmitzii group, was conducted. Morphology was numerically recorded under highly stan- dardised conditions considering absolute size and 16 shape, pubescence and surface characters. A key to the non-parasitic Westpa- laearctic species of the ant genus Plagiolepis Mayr, 1861 is provided which firstly separates, on species group level, the P/. pygmaea (Latreille) species group, the P/. pallescens Forel species group and the P/. schmitzii species group and, finally, on species level, the cryptic species of the latter group. The recognised species of the P/. schmitzii species group are Pl. schmitzii Forel, 1895 (invasive species), P/. barbara Santschi, 1911, Pl. atlantis Santschi, 1920 and Pl. invadens sp. nov. (invasive species) that is described as new from a supercolony in Germany. Based on morphological arguments, the taxa P/. barbara var. madeirensis Emery, 1921, Pl. maura polygyna Santschi, 1922 and PI. schmitzii var. tingitana Santschi, 1936 are recognised as junior synonyms of P/. schmitzii, the taxa Pl. schmitzii crosi Santschi, 1920, P/. pallescens var. kabyla Santschi, 1920 and P/. perperamus Salata et al., 2018 as junior synonyms of P/. atlantis and the taxon P/. maura Santschi, 1920 as junior synonym of P/. barbara. A concluding comparative section suggests that pre-adaptations for anthropogenous dispersal and transformation to supercoloniality in introduction areas are apparently com- mon traits in Plagiolepis ants. Key Words cryptic species, numeric taxonomy, invasive pest species, supercoloniality Introduction The natural distributional range of the ant genus Plagiole- pis Mayr, 1861 includes Africa, Australia and the temper- ate and tropical zones of Eurasia. Close to 100 available names, attributable to this genus, have been published so far. In the absence of a modern and thorough revision, the genus Plagiolepis is assumed to contain 60 valid species, 20 valid subspecies and 10 valid fossil species (AntWeb 2020). This paper is part of a revision of the independent Westpalaearctic species of the genus conducted by the au- thor through the last four years. The situation in the social parasites (inquilines) of Plagiolepis, with a surprisingly high number of undescribed species, is not considered here. The investigation of independently-living species under highly-standardised conditions revealed the pres- ence of at least 11 good species distributed in the Med- iterranean and sub-Mediterranean zoogeographic zones of the Westpalaearctic (this paper and Kirschner et al. in preparation). Morphological discrimination of the many cryptic species in these tiny ants unavoidably requires high-resolution optical systems and highly accurate, re- producible numeric recording of unambiguously defined characters and adequate exploratory and hypothesis-driv- en data analyses. Several papers dealing with some as- pects of Plagiolepis taxonomy of the region were pub- Copyright Bernhard Seifert. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 184 lished during the last decades (Radchenko 1989, 1996; Wetterer et al. 2007; Boer 2008; Sharaff et al. 2011). In- vestigation and analysis methods, quality of equipment and scope of these taxonomic studies were not adequate for the degree of difficulty we encountered here. A disputable paper on Plagiolepis taxonomy was add- ed very recently: Salata et al. (2018) described Plagiole- pis perperamus as new East Mediterranean sister species of Plagiolepis schmitzii Forel, 1895. Detailed comments on this paper are given in the special part below and it was just this particular paper that prompted me to investi- gate all available types of taxa with a taxonomic position close to Plagiolepis schmitzii. Direct type investigation was possible in nine taxa — six of these turned out as junior synonyms. Junior synonymy of two further taxa appeared most probable by geographic indication and/or inspecting photos in AntWeb (2020). Unfortunately, there was no avenue to assess the status of Plagiolepis barbara var. pyrenaica Emery, 1921. The survey, reported here, resulted in the recognition of four verifiable species in the Plagiolepis schmitzii group and the identification of three senior synonyms of P/. perperamus Salata et al. (2018). Material Morphometric characters were recorded in a total of 46 samples and 137 worker individuals from Madeira, the Ca- naries, Europe, North Africa and Asia Minor. Type spec- imens of nine taxa were investigated. Consideration of males and gynes is not performed here for the following reasons: (a) sexual castes are strongly under-represented in the collections and in many taxa unknown, (b) subjective assessment and tentative morphometrics of the few speci- mens available suggested that gynes could provide useful characters for species discrimination, but worker-associated nest samples of gynes were not available in just the critical Species and (c) the author does not know of a single formi- cine ant group worldwide where a clear species separation has been testably demonstrated by means of male genitalia. The material examined is listed in the individual spe- cies treatments in the following sequence and format: site, date in the format yyyy.mm.dd, sample number, [lat- itude in decimal format, longitude in decimal format, al- titude]. The accuracy of coordinates is proportional to the number of decimal points and “xx” in the sampling date sequence means missing data. In some samples without any direct or derived information on date, the name of the collector is given to allow an approximate conclusion on the period of collection. The abbreviations of depositories are as follows: DBU Wroclaw Department of Biodiversity and Evo- lutionary Taxonomy, University of Wroclaw, Poland Museo Civico di Storia Naturale Ge- noa, Italy MCSN Genoa dez.pensoft.net Bernhard Seifert: Revision of the Plagiolepis schmitzii group MHN Genéve Muséum d Histoire Naturelle de Geneve, Geneve, Switzerland NHM Basel Naturhistorisches Museum, Basel, Switzerland SMN Gorlitz Senckenberg Museum fiir Naturkunde Gorlitz, Gorlitz, Germany Methods Equipment and measurement procedures All measurements were made on mounted and dried spec- imens using a pin-holding stage, permitting full rotations around X, Y and Z axes. A Leica high-performance ste- reomicroscope M165C, equipped with a 2.0 planapochro- matic objective (resolution 1050 lines/mm), was used at magnifications of 120—360x. A Schott KL 1500 LCD cold- light source, equipped with two flexible, focally mounted light-cables, providing 30°-inclined light from variable azimuth directions, allowed sufficient illumination over the full magnification range and a clear visualisation of silhouette lines. A Schott KL 2500 LCD cold-light source in combination with a Leica coaxial polarised-light illumi- nator provided optimum resolution of tiny structures and microsculpture at highest magnifications. Simultaneous or alternative use of the cold-light sources depending upon the required illumination regime was quickly provided by regulating the voltage up and down. A Leica cross-scaled ocular micrometer with 120 graduation marks was used. To avoid the parallax error, its measuring line was constantly kept vertical within the visual field. To avoid rounding er- rors, all measurements were recorded in um, even for char- acters for which this precision is impossible. The z-stack photos were made with a Leica Z6 APO photomicroscope, equipped with an objective Planapo 2.0x and a Leica mi- croscope camera DFC420. The morphometric characters and removal of allometric variance Sixteen morphometric characters were investigated in worker ants. In all bilaterally developed characters, arith- metic means of both sides were calculated. The charac- ters are defined as follows: BPdG — mean distance between the base points of pubescence hairs on dorsal plane of 1" gaster tergite. Usually calculated from the sqPDG and PLG data, pro- viding an approximate solution by the formula BPdG = sqrt(PLG*PDG). The direct and exact solution is by counting the number of base points N found within a total area A with BPdG = sart (A/N). CL-— maximum head (cephalic) length in median line; the head must be carefully tilted at highest magnifications to the position with the true maximum. Excavations of hind vertex and/or clypeus reduce CL. Dtsch. Entomol. Z. 67 (2) 2020, 183-196 CS — cephalic size; the arithmetic mean of CL and CW, used as a less variable indicator of body size. CW — maximum measurable head (cephalic) width. The position of measuring line is defined alone by the maximum and may be across or behind the eyes. dAN — minimum distance of the inner (centripetal) margins of antennal socket rings which is best measur- able in dorsofrontal view [see Fig. 271 in Seifert (2018)]. dTP — distance of the centres of clypeal tentorial pits. EL - large diameter of the elliptic compound eye mea- sured over all structurally-visible ommatidiae — 1.e. also including unpigmented ones in a marginal position. F2, F3, F4 — median length of 2™, 3%, 4" funiculus segment in dorsal view. Dorsal view is given when the swivelling plane of 1* funiculus segment is positioned in the visual plane. Take care to really measure median length (the segment’s sides often have unequal lengths!) and to recognise the real distal margin of the segments. The latter may have a very thin cuticle, frequently pro- ducing a narrow, shining ribbon that seems to be, by opti- cal impression, demarcated from the rest of the segment. ML — mesosoma length without neck shield (fringe), posterior measuring point: caudalmost point of metapleuron; parallelism of the measuring line to the longitudinal meso- somal axis has to be considered — 1.e. in lateral view, the an- terior measuring point is found at a lower level of focus. MW — maximum mesosoma width; this is in worker’s pronotal width. PLG — mean length of at least seven pubescence hairs on dorsal plane of 1‘ gaster tergite in the area about 30 to 100 um before posterior tergite margin. In the densely pubescent gasters of P/. schmitzii group species, visual- isation of full hair length may be difficult. Take care to provide adequate illumination, vary viewing positions or perform local ablations of pubescence. These clearings expose full hair length at the margins of the adjacent in- tact pubescence area. PoOc — postocular distance. Use a cross-scaled ocular micrometer and adjust the head to the measuring position of CL. Caudal measuring point: median occipital margin; frontal measuring point: median head at the level of the posterior eye margin. Note that many heads are asymmet- ric and average the left and right postocular distance [see Fig. 146 in Seifert (2018)]. PrOc — preocular distance in lateral view; in Plagiole- pis, the shortest distance between the anterior eye margin to that point of the genal margin which is in closest prox- imity to the dorsal condyle of mandibular joint. SL — maximum straight line scape length (excluding the articular condyle and its neck). sqPDG — square root of transverse pubescence dis- tance PDG [in um] on the dorsomedian part of first gaster tergite about 30 to 100 um before posterior tergite mar- gin. To reduce accidental errors, several countings along differently positioned, transverse measuring lines are av- eraged until the sum of hairs counted is 50 at least. Exact counting is only possible with clean surfaces, high-res- olution stereomicroscopy at magnifications > 280 and 185 reflection-reduced illumination visualising the full length of hairs. Surface spots with torn-off pubescence are ex- cluded from counting. Measuring procedure: the number of pubescence hairs n crossing a measuring line of length L is counted, hairs just touching the line score as 0.5. Mean PDG 1s then L/n. Removal of allometric variance (RAV) was performed with the procedure described by Seifert (2008). RAV en- ables a direct comparison of data of related species in tables and improves the performance of principal compo- nent analyses considerably. RAV was calculated for the assumption of all individuals having a cephalic size of CS = 0.45 mm by overall functions computed as average of specific functions of four species with > 50 workers per species available. These were Plagiolepis schmitzii, Pl. atlantis, Pl. taurica and Pl. occidentalis. The latter name (see Seifert 2018) 1s not available at present, but will be made available by an upcoming paper of Kirschner et al. (in preparation). BPdG, ,, [um] = BPdG / (-6.915 * CS + 26.47) * 23.36 CLICW, ,, = CL/CW / (-0.5438 * CS + 1.3600) * 1.1153 dANICS, ,, = dAN/CS / (0.1248 * CS + 0.1907) * 0.2468 dTPICS, ,, = dTP/CS / ( 0.0857 * CS + 0.4710) * 0.5096 ELICS, ,, = EL/CS / (0.0748 * CS + 0.3109) * 0.2772 F2/CS, 45 [%] = F2/CS / (7.104 * CS + 4.087) * 7.284 F3/CS, ,. [%] = F3/CS / (2.709 * CS + 8.102) * 9.321 F4/CS, , [%] = F4/CS / ( 4.152 * CS + 9.026) * 10.895 F4/F3, ,. = F4/F3 / (0.0883 * CS + 1.1294) * 1.1692 MLICS, ,, = MLICS / (0.4876 * CS + 0.9631) * 1.1825 MWICS, ,, = MWICS / (0.1092 * CS + 0.5846) * 0.6338 PLGICS, ,.[%] = PLGICS / (-11.623 * CS + 13.598) * 8.368 PoOc/CL, ,, = PoOc/CL / (0.2121 * CS + 0.4629) * 0.3674 PrOc/CS,,,, = PrOc/CS / (0.0187 * CS + 0.2278) * 0.2362 SLICS, ,, = SLICS / (0.0204 * CS + 0.9530) * 0.9622 sqPDG, ,, [um] = sqPDG / (2.699 * CS + 4.975) * 3.760 In the species sections, I relinquished presenting verbal descriptions of those morphological characters which may characterise the whole genus or a species group, but are not recognised to have a value for species discrimination. The pictures provided in this paper plus the references to pictures in AntWeb (2020) provide a sufficient overall im- pression on setae, pubescence and surface characters. Explorative and supervised data analyses, classification and statistical testing Analysing the morphometric data, four forms of explor- atory data analyses were run using nest centroids as in- put data (NC clustering). These were firstly hierarchical NC-Ward clustering, secondly and thirdly, the hierarchi- cal method NC-part.hclust and the iterative vector-quan- tisation method NC-part.kmeans — both implemented in partitioning algorithms, based on recursive thresholding (for details see Csdsz & Fisher, 2015) and non-metric multidimensional scaling, combined with iterative vec- dez.pensoft.net 186 tor-quantisation NC-NMDS-k-means (Seifert et al. 2013). A principal component analysis (PCA) of RAV-corrected data was applied when one of the compared species was present in the data pool with only few specimens, making the application of NC clustering not feasible. Checking samples with controversial classifications was done by an interaction of NC clustering and a controlling linear discriminant analysis (LDA) tn which these samples were run as wild-cards, following the rationale described in Seifert et al. (2013). The final classification (“final spe- cies hypothesis”) was established by the LDA in an iter- ative procedure and there remained no undecided cases, even if their posterior probabilities were close to 0.5. The decision to recognise a cluster as a valid species was based on the GAGE species concept (Seifert 2020) — here a< 4% error threshold was applied. LDA, PCA and ANOVA tests were run with the SPSS 16.0 software package. Results The Westpalaearctic species groups of independent Plagiolepis species Based on investigation of type specimens and, in some cases, of only their images in AntWeb (2020), the inde- pendent species of the genus Plagiolepis of the Westpa- laearctic can be subdivided in three major groups: 1 The taxa close to P/. pygmaea Latreille, 1798 which are characterised by the 4 funiculus segment being much longer than the 3 and the rather widely-spaced bas- al pits of pubescence hairs on the dorsum of 1* gaster tergite. Data of 20 nest sample means are 1.631+0.072 [1.510, 1.784] in F4/F3 and 23.68+2.99 [17.7, 28.5] um Bernhard Seifert: Revision of the Plagiolepis schmitzii group in BPdG. The mean BPdG translates into 1783 pubes- cence hairs/mm7?. Without making implications on their potential species status by using here binary names, the described taxa of this group are P/. pygmaea Latreille, 1798, PI. obscuriscapa Santschi, 1922 and Pl. karawa- Jewi Radchenko, 1989. the Plagiolepis pallescens group which 1s character- ised by widely-spaced basal pits of pubescence hairs on the dorsum of 1* gaster tergite (Fig. la) and the 4" funiculus segment not being much longer than the 3" Data of 113 nest sample means are 1.160+0.046 [1.041, 1.292] in F4/F3 and 30.23+1.73 [24.1, 34.2] um in BPdG. The mean BPdG translates into 1099 pubescence hairs/mm?. Without making implications here on their potential species status by use of bina- ry names, the described taxa of this complex are P/. pallescens Forel, 1889, P/. minu Forel, 1911, Pl. tauri- ca Santschi, 1920, Pl. sordida Santschi, 1920, Pi. an- cyrensis Santschi, 1920, Pl. vindobonensis Lomnick1, 1925, Pl. compressa Radchenko, 1996, Pl. dlusskyi Radchenko, 1996, Pl. calva Radchenko, 1996 and PI. sp. OCCIDENTALIS — an undescribed species (name not available at present, Seifert 2018). the Plagiolepis schmitzii group which is characterised by narrowly-spaced basal pits of pubescence hairs on the dorsum of 1* gaster tergite (resulting in a dense pubescence, Fig. 1b) and the 4" funiculus segment not being much longer than the 3. Data of 46 nest sam- ple means are 1.199+0.052 [1.106, 1.362] in F4/F3 and 16.27+1.59 [13.4, 20.2] um in BPdG. The mean BPdG translates into 3778 pubescence hairs/mm?. According to the data currently available, this group contains four species: P/. schmitzii Forel, 1895, Pl. barbara Santschi, 1911, Pl. atlantis Santschi, 1920 and PI. invadens sp. nov. Key to species groups of Plagiolepis and the species of the Pl. schmitzii group Note: This key does not consider the parasitic species (inquilines) of the genus which contain a surprisingly high number of undescribed species and are frequently so tiny in size and so weakly sclerotised that traditional forms of ant preparation appear inadequate. la 4 funiculus segment much longer than 3; F4/F3 > 1.44 [error 0% in 20 nest means. ..............6008 PI. pygmaea group lb 4 funiculus segment only moderately longer than 3; F4/F3 < 1.44 [error 0% in 159 sample means].............::::e 2 2a Dorsum of 1* gaster tergite with widely-spaced pits of pubescence hairs and dilute pubescence cover; BPdG > 22 um, SGP D Gres 70) |GFrOr OZ iiss Sarnipl eaMGaris:|. +. Week geil once ile tlt Moe be wld ae om Mecelys PI. pallescens group 2b Dorsum of 1% gaster tergite with densely-spaced pits of pubescence hairs and dense pubescence cover; BPdG < 22 um, SqeDG <-s9/0. error 09, In 46‘Sample Meals Pl SENNWEZH SrOU Bs. sates re ons be ae oak Pee ee oes reas feaeee steeds es ats UP 3 3a 3’ funiculus segment short; with measurements in mm, discriminant 355*F3-35.54*CW+ 1.879 2.3 [error 0% in 3 sample Means MOLoCCereaseto Tunis ai t.cr Pls... crre han oermmiacer co, RVWNe PISS, AM Pry he. WP ANT Seen ROP 7 TUN Uerice res SE. Moye, P|. barbara 4b Eye length and distance of pubescence hair pits smaller (EL/CS 0.274+0.16, BPdG 16.18+41.72). Sample means of CISGriniitienit 23 (EKKO OI eA GaSe METIS: kin kee Beate Veta aod cee ae any os sO ree NAR ss eerie ieee 8 5 5a Withall measurements in mm, discriminant 48.98*CL+72.21*PoOc-65.80*SL-171.2*F44+173.5*PLG+35.42*MW-12.79 EO FEFFOROSS INOS I CIM CUES nee ea Sarre ER RR a rere ts Pe Te av awe ry Eo, RANE hal deceit hin We PI. schmitzil Sh. Siscriimbant se). (error | SoZ ot ipo Cal CIV CHAS! Wax: ue, sce ccen ate MMR sa reebateds yu dadorechsd ny See Bals MEN hatte pene PI. atlantis dez.pensoft.net Dtsch. Entomol. Z. 67 (2) 2020, 183-196 Figure 1. Surface of posterior part of 1“ gaster tergite of a work- er of Plagiolepis taurica (a) and PI. schmitzii (b). Treatment by species Plagiolepis schmitzii Forel, 1895 Plagiolepis pygmaea var. schmitzii Forel, 1895 Published type locality: “Serra d’Agua, Madeira (Seminardirektor P. E. Schmitz)” [32.727°N, 17.027°W, 347 m alt.]. Nine paratype workers were investigated from MHN Geneve collected by Schmitz in at least three localities in Madei- ra. Amongst these were workers pictured in AntWeb (2020), labelled “Pl. pygmaea Latr. v. schmitzii For. Garajau Madeira Schmitz 3, 5-9”, “ANTWEB CASENT0909859”. All investigated specimens do not carry a label pointing to Serra d’Agua. I also investigated the lectotype gyne labelled “Pl. pygmaea Latr. v. schmitzii For. Madeira (Schmitz)”, “ANTWEB CASENT0909858”, “LECTOTYPE (upper) Plagiolepis pygmaea var. schmitzi Forel, 1895 desig. Wetterer & Espadaler”. Plagiolepis barbara var. canariensis Santschi, 1920 [syn. schmitzii| Described from Tenerife: La Laguna, Bejano and Esperanze. No type specimens or figures of this taxon were available and the de- scriptive statements of Santschi are useless. A junior synonymy with Pl. schmitzii appears probable for zoogeographic reasons. Plagiolepis barbara var. madeirensis Emery, 1921 [syn. schmitzii| Identification by evaluation of photos of a type worker in AntWeb (2020) labelled “Pl. barbara var. madeirensis Em.”, “SYNTYPUS Plagiolepis barbara var. madeirensis Emery, 1921”, “Funchal Ma- deira De Guerne”, “ANTWEB CASENT0905 140”. Plagiolepis maura polygyna Santschi, 1922 [syn. schmitzii| Four type workers were investigated from NHM Basel labelled “Tunisie, Cheri Chera 27 III 21 Santschi’. Plagiolepis schmitzii var. tingitana Santschi, 1936 [syn. schmitzii| Santschi published as collecting sites “Tanger w. (type) et Volubilis w. (Alluaud)”. Four type workers were investigated from NHM Ba- sel labelled “Tanger Ch. Alluaud”. 187 Material examined. A total of 21 samples with 64 work- ers were subject to morphometric investigation. Algeria: Mascara, 1926 [35.398°N, 0.138°E, 594 m alt.]. England: Isle of Wight: Bonchurch, 2007.06.21 [50.59°N,1.19°W, 3 m_ alt.]|. Germany: Schkeu- ditz, 2019.02.11 [51.392°N, 12.204°E, 104 m_alt.]; Schriesheim, 2017.05 [49.470°N, 8.46°E, 118 m alt.]; Seligenstadt, 2009.04 [50.045°N, 8.975°E, 115 m alt.]. Morocco: Chefchaouen, 2009.03 [35.183°N, 5.300°W, 400 m alt.]; Meknes, 1940.02.02 [33.894°N, 5.547°W, 551 m alt.J; Rabat (Santschi) [33.973°N, 6.845°W, 84 m alt.|; Tanger (Alluaud), type P/. schm. tingitana [35.755°N, 5.819°W, 30 m alt.]; Tiz-n-Test —8 km N, 1987.05.05, No 13015 [30.889°N, 8.370°W, 1810 m alt.]. Netherlands: Brakel, 2013.02 [51.820°N, 5.093°E, 2 m alt)|;; Fholen,.2019°05.27,[51,.5392N\4221 7° R alemealt: |; Utrecht, 2006.09.09 [52.09°N, 5.12°E, 10 m alt.]. Por- tugal: Madeira: Estreito da Calheta, 2009.03 [32.733°N, 17.167°W, 350 m alt.]; Madeira, 1400 m (Schmitz), para- types PI. schmitzii [33.0°N, 17.0°W, 1400 m alt.]; Madei- ra: Garajau (Schmitz), paratypes P/. schmitzii [32.64°N, 16.85°W, 230 m]; Madeira: Palheiro (Schmitz), paratypes Pl. schmitzii [32.65°N, 16.87°W, 360 m alt.]. Spain: La Palma: Todoque, 2010.03.02 [28.617°N, 17.903°W, 334 m alt.]; Tenerife: Las Canadas NP, 1999.06.02 [28.26°N, 16.61°W, 2300 m alt.]; Sevilla, 2019.06.24 [37.394°N, 5.994°W, 10 m alt.]. Tunisia: Cherichara, 1921.03.27, types P/. polygyna [35.637°N, 9.815°E, 255 m alt.]. Diagnosis and taxonomy (Table 1, key, AntWeb, 2020: CASENT0906252, Figs. 2-4): PI. schmitzii has the longest scape and funiculus seg- ments within the species group. The most similar species is Pl. atlantis, whereas Pl. barbara and Pl. invadens sp. nov. appear more distant and have much shorter scapes (for their status, see there). The material allocated here to PI. schmitzii (21 samples, 64 specimens) and P/. atlantis (20 samples, 56 specimens) were investigated by explor- atory data analyses (EDAs). Considering absolute head size and all 16 allometrically-corrected shape, pubescence and surface characters, NC-Ward, NC-part.kmeans, NC- NMDS-kmeans, a principal component analysis (PCA) and NC-part.hclust confirmed two clusters. The classifi- cation of the first four EDAs agreed for each of the 41 samples, whereas NC-part.hclust exposed two samples as indeterminate outliers (Fig. 5). If these two samples were run as wild-cards in a controlling linear discriminant analysis (LDA), they were classified in agreement with the first four EDAs. The classification error of the LDA on an individual level was 0.7 % in 120 workers. All these data are a clear indication of separate species identity of PI. schmitzii and Pl. atlantis. Running the type series of seven taxa as wild-cards in the LDA resulted in clear al- locations to either cluster. The posterior probabilities for allocation to the P/. schmitzii cluster were 1.000 in each of the three paratype series of P/. schmitzii from Madeira, 0.999 in the type series of P/. polygyna and 1.000 in the type series of P/. tingitana, whereas the posterior proba- bilities for allocation to the P/. atlantis cluster were 1.000 in the type series of P/. atlantis, 0.916 in the type series dez.pensoft.net 188 Bernhard Seifert: Revision of the Plagiolepis schmitzii group Mi si: wa Figure 2. Head of a worker of Plagiolepis schmitzii (image from AntWeb, 2020: CASENT0906252, photographer E. Ortega). Figure 3. Lateral aspect of a worker of Plagiolepis schmitzii (image from AntWeb, 2020: CASENT0906252, photographer E. Ortega). dez.pensoft.net Dtsch. Entomol. Z. 67 (2) 2020, 183-196 189 Figure 4. Dorsal aspect of a worker of Plagiolepis schmitzii (image from AntWeb 2020: CASENT0906252, photographer E. Ortega). of P/. crosi, 0.994 in the type series of P/. kabyla and 0.998 in the type series of P/. perperamus. All five EDAs allocated any type series in agreement with the LDA wild-card runs. As a consequence, P/. polygyna and PI. tingitana are junior synonyms of P/. schmitzii, whereas PI. crosi, Pl. kabyla and Pl. perperamus are junior syn- onyms of P/. atlantis. Without types of Plagiolepis bar- bara var. madeirensis Emery, 1921 being available, the synonymisation of this taxon with Pl. schmitzii is highly probable for two reasons: (1) the scape is very long: the data of SL and CW, as they can be derived with minimum distortions from the CASENT0905140 photo of the P/. b. madeirensis type, are within the P/. schmitzii cluster and outside the cluster formed by P/. atlantis, P/. invadens sp. nov. and Pl. barbara; (2) Madeira seems to be inhabited by only a single, very abundant Plagiolepis species which is to be named PI. schmitzii. Distribution and biology. According to direct in- vestigation of voucher specimens, P/. schmitzii is dis- tributed from Madeira and the Canaries across West Mediterranean Africa east to Tunisia. There are anthro- pogenous introductions north of 46°N. In Germany, it has been found so far only in houses, with workers oc- casionally foraging outdoors. However, year-round out- door nesting has been recently reported from two sites in the Netherlands (Jinze Noordijk pers. comm. 2020). Accordingly, there is a clear potential for becoming an established neozoon in NW and Central Europe in the context of global warming. Polygyny and polydomy with colony territories over several houses is confirmed for populations in the Netherlands and Germany. The population from Madeira, Estreito da Calheta is obliga- tory polygynous and highly polyandrous (a queen may have up to 14 different mates), whereas the population from Chefchaouen in Morocco is facultatively polygy- nous and moderately polyandrous (Thurin et al. 2011). These authors stated that relatedness within colonies re- mains high because of sib-mating and relatedness of the male mates of a queen (fixation index F’, = 0.24 in the Madeiran and 0.26 in the Moroccan population). Small size, polygyny with intranidal mating and broad food spectrum are pre-adaptations for a career as a tramp spe- cies. Pl. schmitzii is everywhere present in Madeira and rivals there in abundance with Lasius cf. grandis Forel. Plagiolepis atlantis Santschi, 1920 Plagiolepis maura var. atlantis Santschi, 1920 Three gyne and five worker syntypes were investigated from NHM Basel, labelled “Plagiolepis Type maura Sants v. atlantis Santi”, “13.”, “Tu- nisie Dir el Kef Dr. F. Santschi’, “mai 1913”, “type”, “ANTWEB CASENT0912421”. Plagiolepis schmitzii crosi Santschi, 1920 [syn. atlantis] Three type workers were investigated from NHM Basel, labelled “Plagiole- pis crosi. Sants”, “Algerie Mascara A-Cros.” and “ANTWEB CASENT0912429”, Plagiolepis pallescens var. kabyla Santschi, 1920 [syn. atlantis] Three type workers were investigated from NHM Basel, labelled “Plagi- olepis maura Sant v. kabyla Sant type”, “Tunisie Ain Draham Sants- chi 1913”, “Type”, “ANTWEB CASENT0912423”. The type speci- mens are pale yellowish and thus paler than usually seen. Plagiolepis perperamus Salata et al., 2018 [syn. atlantis] Three paratypes were investigated from the holotype nest, labelled “LBC-GR00042”, dez.pensoft.net 190 “GREECE NW Crete | 3 km S Askifou 800 m a.s.1.| 35°16'N/24°10'E | 1 V 2007. L.& M.L. Borowiec”; depository DBU Wroclaw. Material examined. A total of 20 samples with 56 work- ers were subject to morphometric investigation. Algeria: Azeffoun, 1986.04.13 [36.89°N, 4.41°E, 5 m alt.]; Chrea, 1965.05.14 [36.47°N, 2.91°E, 900 m alt.]; Col de Temet, 1986.04.06, samples No 12518- 12522 [35.596°N, 0.050°E, 1600 m alt.]; Dshebel Che- lia, 1986.04.06, No 12509 [35.32°N, 6.66°E, 2100 m alt.]; Marnia, Cap. Boitel (Santschi) [34.85°N, 1.73°W, 410 m alt.]; Mascara, 1920, type of Pl. crosi [35.40°N, 0.14°E, 603 m alt.]. Greece: Agios Mamas, salines, 2009.09.04 [40.217°N, 23.333°E, 4 m alt.]; Agios Niko- laos — 3 km E, 2010.04.19 [38.894°N, 21.889°E, 1112 m alt.]; Askifou-3 km S, 2007.05.01, type P/. perper- amus [35.267°N, 24.176°E, 800 m alt.]; Kassandra, Sividri, 2009.08.25 [40.033°N, 23.350°E, 6 m_ alt.]; ésbos: Petri, 2012-05723. (89.323°2N. 26:192°R,_ 158 m alt.]. Morocco: Sidi Smail—8 km N, 1987.05.04, No 12991 [32.873°N, 8.876°W, 137 m alt.]; Tiz-n-Test-8 km N, 1987.05.05 [30.889°N, 8.370°W, 1810 m alt. ]. Tunisia: Ain Draham, 1913, type P/. kabyla [36.779°N, 8.687°E, 764 m alt.]; Dir el Kef, 1913.05, type Pl. at- lantis [36.17°N, 8.70°E, 594 m alt.]. Turkey: Ankara (Santschi) [39.93°N, 32.86°E, 890 m alt.]. Diagnosis and taxonomy (Table 1, key, AntWeb, 2020: pictures of specimen CASENT0912421): The clear separation from P/. schmitzii by explorato- ry and hypothesis-driven data analyses has been demon- strated above. As Santschi described the synonyms PI. atlantis, Pl. crosi and PI. kabyla within the same paper (Santschi 1920), the priority of P/. atlantis was fixed by the reviser’s decision. P/. atlantis differs from P/. bar- bara by having smaller eyes and larger preocular and postocular distance and from P/. invadens sp. nov. by a much longer 3™ funiculus segment. For the clear sepa- ration from these species by exploratory data analyses, see there. It is my duty here to comment on the paper of Salata et al. (2018). These authors introduced a new species P/. perperamus and made attempts to suggest its heterospecificity from P/. schmitzii. Regarding the morphological separation of the two entities, they wrote nothing but two sentences: “...their separation using morphological characters such as size, body colouration and gaster setosity is very challenging (Table 1). In most cases both species differ in length of gaster setosity. In P. perperamus setae are long enough to cover at least 1/2 of the length of following setae and in P. schmitzii they cover approximately 1/4 of the length of the following setae”. Firstly, I agree with Salata et al. (2018) that the separation is challenging. Data of absolute measurements and body ratios given in their table 1 show, indeed, a huge interspecific overlap for any presented character, making a reader believe that these characters could be useless for species separation. Secondly, the authors are not familiar with the accepted terminology of ant dez.pensoft.net Bernhard Seifert: Revision of the Plagiolepis schmitzii group morphology. What they have called “setosity” and “setae” truly refer to pubescence which dramatically differs in size, spatial arrangement and microstructure of the hairs from those structures consistently named by dead and living ant taxonomist as true setae or pilosity. Thirdly, if only the length of gastral pubescence hairs were believed to be a rather good separating character, why did Salata et al. not present concrete data in their table 1? Having measured these data carefully and in a larger sample, they would have become aware that a weak difference of mean values is invalidated in its taxonomic significance by a huge overlap range. According to investigations presented here, absolute length of pubescence hairs on dorsum of 1* gaster tergite (PLG) in micron as the mean of seven measurements per individual and over the whole geographic range is 30.6+2.0 [26.5, 35.4] in 64 workers of P/. schmitzii and 32.842.3 [28.0, 38.1] in 56 workers of P/. atlantis (= PI. perperamus). Fourthly, the full absence in the text of concrete verbal or numeric data on characters of type specimens of taxa of the P/. schmitzii group in the paper of Salata et al. (2018) indicates that there was no thorough direct investigation of type specimens. There was putatively a subjective eye inspection by Sebastian Salata during his visits of NHM Basel and MHN Geneve, but the curators of both museums Isabelle Zurcher and Bernard Landry confirmed that there has been no loan of any Plagiolepis type specimen by one of the three co-authors. In the absence of a conclusive morphological argu- mentation, Salata et al. (2018) used a survey of Med- iterranean climate variables, showing that precipitation in the coldest quarter of the year significantly differs be- tween the East and West Mediterranean zone. The con- clusion of Salata et al. (2018) from this was that, amongst those Mediterranean Plagiolepis ants with dense pubes- cence on gaster tergites, there were two different allopat- ric or parapatric species, because “climate niches” in the east and west of the area differed. The applied taxonomic working philosophy reads as follows: if we cannot show a morphological difference in a sample of animals dis- tributed over a certain geographic area, it 1s sufficient to demonstrate a significant difference of regional meteoro- logical data to subdivide this sample into different spe- cies and that describing a new species can be done with- out a thorough direct investigation of type specimens of some 12 candidate taxa for senior synonymy. Distribution and biology. P/. atlantis has obvious- ly a more eastern distribution than P/. schmitzii, but the ranges of both species overlap in North Africa over at least 1800 km (9°W to 10°E). Pl. atlantis is so far not known to occur as a tramp species in sub-Mediterranean or temperate Europe — neither outdoors nor in houses. Occurrence east of Turkey seems credible, but needs confirmation by reliably-determined voucher specimens. Salata et al. (2018) reported it to nest in soil, usually be- low stones and to be associated with humid areas over- grown by macchia or forests. Colonies are polygynous. Dtsch. Entomol. Z. 67 (2) 2020, 183-196 = ; — us —— oo & 2 & 2 3 3s 8 & = 3 & & & 3 a & a 4 & & & beh fied be be SOE Poe 2g -_ =- = = i= = eo pas Se 6&6 & = & B & § $ S 8 = S 3s ess ass 4a s § F Zs es 8 S FS a gee aD hd Mee Faas ae Lee Bo ot AS os ZS Shoe oS oe 59k Se eA eS 6s &§ S$ BS SS KEE Ree YF Ss 8B oe wy oO oO o oO 2 oO oO oO a = o o a & i o oO o 0 Oo 0 oo Oo = oS oO o o £ i] eae Ge 2 2 9 ISH SB SB FFF B&F SAAD K Aramis ortyeele ed) Sie Ee a That). og See is SRBReeES BS Pe SSetEs 455 2 8G © an Eo EF SF Ss ¥ 1 1 > £5 6 6 O 6 £ & &€ & f 1 © = 2 E o a wat a i} F, (e) La g ‘e o