Seladonia (Vestitohalictus) vestita (Lepeletier, 1841) and Seladonia (Vestitohalictus) tecta (Radoszkowski, 1875)

The taxonomic status of Seladonia (Vestitohalictus) vestita tecta (Radoszkowski, 1875) requires clarification. Ebmer (1988a: 573) returned this taxon to species status from the previous combination with S. vestita . Ebmer (1988a: 576) considered S. vestita to be restricted to Iberia, southern France [locus typicus: Montpellier, Lepeletier (1841: 281)], and the Balearic islands, whereas S. tecta is a steppic species found from southern France across Europe to Mongolia. Ebmer (1976: 398) designated the lectotype of S. vestita in Paris, and later (Ebmer 1988a: 573) designated the lectotype of S. tecta in Berlin. This revalidation of S. tecta has not received universal acceptance. The name S. vestita continued to be used as the sole European species by some authors (Nieto et al. 2014; Ortiz-Sánchez & Pauly 2017), whereas S. tecta was used by Central European workers for populations in their regions (Schwarz et al. 1996; Amiet et al. 2001; Józan 2011; Praz et al. 2023).

Analysis of COI barcodes has revealed a complex picture (Fig. 12). Sequences from southern France (Bouches-du-Rhône, Vaucluse), Corsica, Austria, Greece (mainland, Aegean islands, and Crete), and Lebanon, as well as from the United States, where it has been introduced (Scarpulla 2013), cluster together with bootstrap support of 78. Sister to this cluster are sequences from Portugal (Algarve), Spain (Murcia, Segovia), and Morocco (Fès-Meknès), with bootstrap support of 82. These two clusters are separated by an average of 1.80%, but the range of separation is 0.53–3.11%. Sequences HALAE062-19 ( S. vestita, Portugal, Algarve) and HALAE068-19 ( S. tecta, Greece, Santorini) were separated by just 0.53%, and sequences IBIHM342-21 ( S. vestita, Spain, Segovia) and MH319300 ( S. tecta, Austria) were separated by 3.11%. Average variation within S. vestita was 0.45% (range 0.00–1.01%) and within S. tecta was 0.54% (0.00–1.45%). If considered as distinct species, then the minimum interspecific separation is almost the same as the average intraspecific variation.

The result cannot immediately be translated onto the current taxonomic framework. Since the locus typicus of S. vestita is Montpellier, the sequences from Bouches-du-Rhône and Vaucluse are geographically only separated by around 100 km. In contrast, the closest sequences from Spain are separated by around 700 km. It is possible that topotypic sequences from Montpellier could fall into either clade, meaning that the name S. vestita sensu stricto could potentially be applied to either the West Mediterranean or Central European population. Additionally, further genetic sampling from northern Spain and south-western France may show that there is no consistent genetic separation across a broad clade from Iberia to Greece and Lebanon. In the work of Ebmer (1975a), written before he designated the lectotype of S. vestita in Paris (Ebmer 1976), Ebmer considered two taxa, S. vestita (the name applied to the Central European population) and S. velata Pérez, 1895 (the name applied to the West Mediterranean population). Ebmer (1976) later treated S. vestita as the senior synonym of S. velata, and resurrected S. tecta for the Central European population (Ebmer 1988a).

Given that the strongest characters to allow separation of the two clades are based on male characters (the size of the hair tuft on the male sternum 4 and the shape of the male gonostylus; Ebmer 1975a), and the lectotype of S. vestita is a female from a locus typicus that falls between the two observed genetic clades, there is a risk of nomenclatural instability in treating S. tecta as a valid species at the present time.

Additionally, S. vestita has not previously been recorded from North Africa. The barcoded specimens from Boulemane could indicate that either i) specimens from central and southern Iberia are actually a different taxon that is not conspecific with S. vestita sensu lato or ii) that S. vestita is present also in North Africa, which would not be surprising since Boulemane has produced records of other bee species previously thought to be restricted to Europe (e.g. Wood 2023d).

We therefore continue to use S. vestita in a broad sense until clarity is achieved, either through the establishment of a precise geographical transition point in southern France based on dissected males or topotypic genetic samples from Montpellier and its surroundings. The listing of just S. vestita as used in the 2023 checklist is maintained pending further investigation.