Plagiolepis atlantis Santschi, 1920

Bernhard, Seifert, 2020, Revision of the Plagiolepis schmitzii group with description of Pl. invadens sp. nov. - a new invasive supercolonial species (Hymenoptera: Formicidae), Deutsche Entomologische Zeitschrift 67 (2), pp. 183-196 : 183

Plagiolepis atlantis Santschi, 1920

Plagiolepis maura var. atlantis Santschi, 1920 Three gyne and five worker syntypes were investigated from NHM Basel, labelled " Plagiolepis Type Plagiolepis maura Sants v. Plagiolepis atlantis Santi", “13.”, "Tunisie Dir el Kef Dr. F. Santschi", "mai 1913", “type”, "ANTWEB CASENT0912421".

Plagiolepis schmitzii crosi Santschi, 1920 [syn. Plagiolepis atlantis ] Three type workers were investigated from NHM Basel, labelled " Plagiolepis Plagiolepis crosi . Sants", "Algerie Mascara A-Cros." and "ANTWEB CASENT0912429".

Plagiolepis pallescens var. kabyla Santschi, 1920 [syn. Plagiolepis atlantis ] Three type workers were investigated from NHM Basel, labelled " Plagiolepis maura Sant v. Plagiolepis kabyla Sant type", "Tunisie Ain Draham Santschi 1913", “Type”, "ANTWEB CASENT0912423". The type specimens are pale yellowish and thus paler than usually seen.

Plagiolepis perperamus Salata et al., 2018 [syn. Plagiolepis atlantis ] Three paratypes were investigated from the holotype nest, labelled “LBC-GR00042”, "GREECE NW Crete | 3 km S Askifou 800 m a.s.l.| 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 workers 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 Chelia , 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 Nikolaos - 3 km E, 2010.04.19 [38.894°N, 21.889°E, 1112 m alt.]; Askifou- 3 km S, 2007.05.01, type Pl. perperamus [35.267°N, 24.176°E, 800 m alt.]; Kassandra, Sividri, 2009.08.25 [40.033°N, 23.350°E, 6 m alt.]; Lesbos: Petri, 2012.05.23 [39.323°N, 26.192°E, 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 Pl. kabyla [36.779°N, 8.687°E, 764 m alt.]; Dir el Kef, 1913.05, type Pl. atlantis [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 Pl. schmitzii by exploratory and hypothesis-driven data analyses has been demonstrated above. As Santschi described the synonyms Pl. atlantis , Pl. crosi and Pl. kabyla within the same paper ( Santschi 1920), the priority of Pl. atlantis was fixed by the reviser’s decision. Pl. atlantis differs from Pl. barbara by having smaller eyes and larger preocular and postocular distance and from Pl. invadens sp. nov. by a much longer 3rd funiculus segment. For the clear separation 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 Pl. perperamus and made attempts to suggest its heterospecificity from Pl. 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 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 1st 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 Pl. schmitzii and 32.8 ± 2.3 [28.0, 38.1] in 56 workers of Pl. atlantis (= Pl. perperamus ). Fourthly, the full absence in the text of concrete verbal or numeric data on characters of type specimens of taxa of the Pl. 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 Genève, but the curators of both museums Isabelle Zürcher 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 argumentation, Salata et al. (2018) used a survey of Mediterranean climate variables, showing that precipitation in the coldest quarter of the year significantly differs between the East and West Mediterranean zone. The conclusion of Salata et al. (2018) from this was that, amongst those Mediterranean Plagiolepis ants with dense pubescence on gaster tergites, there were two different allopatric 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 distributed over a certain geographic area, it is sufficient to demonstrate a significant difference of regional meteorological data to subdivide this sample into different species and that describing a new species can be done without a thorough direct investigation of type specimens of some 12 candidate taxa for senior synonymy.

Distribution and biology.

Pl. atlantis has obviously a more eastern distribution than Pl. 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 below stones and to be associated with humid areas overgrown by macchia or forests. Colonies are polygynous.