Corresponding author: Sándor Csősz (
Academic editor: Matthew Prebus
In this paper, we provide numeric morphology-based evidence that the dark-colored
Csősz S, Kiran K, Karaman C, Lapeva-Gjonova A (2022) A striking color variation is detected in
The taxonomy of the European representatives of the tiny hypogeic genus
This problem prompted us to examine the possibility of whether a third
We compared the morphologically recognized clusters with the color patterns of the samples. As a result, the third
In this research 10 continuous morphometric traits were measured on 165 workers belonging to 73 nest samples. The material is deposited in the following institutions: Entomological Museum of Trakya University (
Austria:
“BLACK MORPH”
“PALE MORPH”
Distribution map for all species discussed in this revisionary work is generated via SimpleMappr (
Pigmentation scaling was performed via a subjective evaluation of body coloration ranging from whitish yellow (score 1) to black (score 5). The specimens were illuminated via Photonic Optics 2-arms Illuminator with neutral white color temperature, 5900 K (equivalent to halogen, 4000 K). Specimens with light pigmentation (score 2 and score 3) were classified as “pale morph” (Fig.
Light-colored (score 2)
A syntype worker of
Morphometric characters are defined as in
The statistical procedure has been done on worker caste only. The prior species hypothesis was generated based on workers through the combined application of NC clustering (
Structure in morphometric data was also displayed in a scatterplot via a principal component analysis (
The validity of the prior species hypothesis imposed by the two exploratory processes was tested via a cross-validated linear discriminant analysis (
Altogether two clusters were revealed to be the most parsimonious solution by both NC-
Dendrogram solution for the Western Palaearctic representatives of
Gap statistic for dataset of Western Palaearctic
Ordination biplot for shape principal component analysis (
We hold
Geographic distribution of
The distinctive morphology of these species allows for considerable reduction of morphological characters, so that workers of the two taxa
The best morphometric ratio (petiole length / petiole height;
Coefficients of linear discriminants help to place and identify samples via placing workers in the discriminant space using the linear discriminant function (LD) as follows (morphometric traits are in micrometers):
LD = 0.0449*
A simple morphometric ratio of two petiole characters (petiole length / height of petiolar node,
The yellow and black
Although the yellowish phenotype of
Geographic map of
In conclusion, relying solely on color patterns is not a robust approach in identifying European
This study was partially supported by the National Research, Development, and Innovation Fund under grant no. K 135795 (S.C) and the Scientific and Technological Research Council of Turkey (TÜBİTAK) projects no. 109T088 and 111T811 (K.K.). Special thanks are due to Phil Attewell for kindly improving the language of the manuscript. We also wish to thank the three reviewers, J.J. Longino, B. Seifert, and H.C. Wagner, for their constructive critiques that helped to improve the manuscript’s quality.