Thyreus truncatus ( Pérez, 1884 )

Wood, Thomas, Leclercq, Vincent, Schmid-Egger, Christian & Praz, Christophe, 2025, A contribution to the knowledge of the genus Thyreus Panzer in the West and Central Palaearctic (Hymenoptera, Apidae), with two new species, taxonomic updates, host relationships, and a key to European species, Deutsche Entomologische Zeitschrift 72 (2), pp. 259-302 : 259-302

publication ID	https://doi.org/10.3897/dez.72.164496
publication LSID	lsid:zoobank.org:pub:8DD12B45-AE34-45B8-A8FB-0C3A13478718
DOI	https://doi.org/10.5281/zenodo.17525163
persistent identifier	https://treatment.plazi.org/id/93D81338-8F70-5AEF-A0C4-481FEDCB6EE0
treatment provided by	Deutsche Entomologische Zeitschrift by Pensoft
scientific name	Thyreus truncatus ( Pérez, 1884 )
status

Treatment

Thyreus truncatus ( Pérez, 1884) View in CoL

Crocisa truncata Pérez, 1884: 312, ♂ [ France, MNHN, examined] (Fig. 6). View in CoL

Crocisa ramosa var. mucorea Friese, 1925: 30, ♀ [ Egypt, ZMHB, examined] (Fig. 7). View in CoL

Crocisa nadigi Alfken, 1933: 136, ♀ ♂ [ Morocco, ZMHB, examined] (Fig. 8). View in CoL

Crocisa curviscutum Alfken, 1934: 167, ♀ ♂ [ Egypt, ZMHB, examined] (Fig. 9). View in CoL

Material examined.

Egypt • 1 ♀; Heliop. [Heliopolis] ; 21 Apr. 1896; O. Schmiedeknecht leg.; ZMHB ( holotype of Crocisa ramosa var. mucorea ) • 3 ♀; Pyramids ; 12 May 1914; Adair leg.; ZMHB ( holotype and paratypes of Crocisa curviscutum ) ; France • 1 ♂; Mpeli [Montpellier] , 980 [ Pérez catalogue number]; MNHN ( lectotype by present designation) ; Kyrgyzstan • 2 ♂; 50 km W Naryn ; 21 Jul. 2019; K. Janssen leg.; KJCB • 1 ♂, 1 ♀; 45 km W Naryn ; 20 Jul. 2019; K. Janssen leg.; TJWC ; Moldova • 2 ♂; Kišiněv [Chişinău]; 1–30 Jun. 1995; I. Pavilčok leg.; OÖLM ; Morocco • 1 ♂, 2 ♀; El Hajeb ; 22 Jul. 1932; Ad. Nadig leg.; ZMHB (male holotype, female paratypes of Crocisa nadigi ) . Additional examined specimens are detailed in Suppl. material 1.

Notes.

Lieftinck (1968) gave the publication year of Crocisa truncata as 1883, but Baker (1996) identified that the work of Pérez ( Contribution à la faune des apiaires de France. Deuxième Partie) was published in three tranches, with pages 257–320 issued in February 1884. The description of T. truncatus was therefore published in 1884. A single syntype was preserved in the MNHN until at least the 1930 s, as it was inspected by de Beaumont (1940: 167), but seemingly not by Lieftinck (1968). Moreover, de Beaumont (1940) did not indicate the label information of this syntype, which is important because Pérez (1884) described the species from “ Provence et Languedoc ”. In the unpublished catalogue of Pérez ( https://science.mnhn.fr/catalogue/ey-bib-perez1/), on page 164, species entry 980 lists: “ Crocisa truncata J. P. Montpellier 1 ♂ ”. This syntype was located during a recent visit to the MNHN in September 2025 (Fig. 6 View Figure 6 ); it is indeed a male specimen from Montpellier bearing the catalogue number 980 (Fig. 6 A View Figure 6 ) and is hereby designated as the lectotype. It is not dissected, but the short scutellum is clearly visible (Fig. 6 C View Figure 6 ), confirming the current interpretation of the species in a general sense.

DNA barcoding analyses revealed three mitochondrial lineages within Thyreus truncatus sensu lato: an Iberian lineage, a Euro-Siberian lineage, and a French lineage (Fig. 1 View Figure 1 ). These lineages were separated by genetic distances of between 1.53 and 4.16 %. Two of these lineages are present in the south of France, the terra typica of T. truncatus : the widespread Euro-Siberian lineage (east to Kyrgyzstan), which descends from Switzerland along the Rhône River to Saint-Étienne-des-Sorts (Département Gard), and just 35 kilometres further south, at Châteaurenard (Département Bouches-du-Rhône), the French lineage is detected. This second lineage is also found in Montredon-des-Corbières (Département Aude) in south-western France. Based on collecting locality, the lectotype of T. truncatus would probably belong to the French mitochondrial lineage, but topotypic sampling is required.

Morphologically, based on barcoded specimens examined for morphology, specimens from the Iberian and Euro-Siberian lineages appear separable in some cases (Table 1 View Table 1 ), particularly with reference to the male genitalia and the density of punctation on the outer face of the apex of the gonostylus. However, specimens from France, including those from the French lineage and the lone barcoded specimen from the Euro-Siberian lineage (specimen number 2492 in Fig. 1 View Figure 1 ), display an intermediate morphology in puncture density.

Given the inability to recognise three consistently and morphologically distinct forms, with specimens from southern France presenting an intermediate morphology; the presence of at least two mitochondrial lineages in close proximity in southern France; and the lack of genetic data from Egypt and Morocco – the countries from which the names with the next oldest priority arise (Figs 7 View Figure 7 – 9 View Figure 9 ) – any taxonomic action at the present time presents a serious risk of nomenclatural instability. It may be the case that Iberian “ T. truncatus ” could be treated as T. nadigi in a future revision, but this is currently premature. We therefore take no action and maintain a broad concept of T. truncatus , in line with the concept and synonymies established by Lieftinck (1968), pending further study. Such future studies should further investigate species delimitation in this widespread taxon, delineate the distribution of the two mitochondrial clades found in France, and examine morphological variation with longer series of specimens.

Ecologically, the host in at least the German and Austrian parts of its range is Tetralonia dentata (Germar, 1839) ( Schmid-Egger et al. 2022) , which has an overall distributional range stretching from Morocco to Central Asia ( GBIF. org 2025). Collections in Spain (TJW) have produced T. truncatus at sites where Te. dentata was caught abundantly (provinces of Segovia in 2019 and Ávila in 2020), and Te. dentata is often present with T. truncatus in southern France (M. Aubert, pers. comm.). One female of T. truncatus was collected flying over a nesting site of Te. dentata in southern France (CP, M. Aubert and E. Dufrêne, pers. obs.). Overlaying Te. dentata distributional data from GBIF, there is a broad correspondence in the distribution (Fig. 10 View Figure 10 ), although GBIF data for Te. dentata are lacking for Greece, the Levant, and the Caucasus, areas where this species is known to occur ( Kuhlmann et al. 2014; Ascher and Pickering 2025). There are clear areas of close correspondence in central Spain, southern France, south-western Switzerland, eastern Austria, and eastern Germany. However, Te. dentata does not appear to have been recorded from Egypt, the locus typicus for both T. mucoreus and T. curviscutum . In general, the distributional similarities are closer in the west but weaker in the east, where greater revision of Te. dentata specimen data is required.

Interestingly, Te. dentata also shows considerable variation in the COI gene. The sequence of Te. dentata published by Wood et al. (2024) from Ávila forms a unique BIN ( BOLD: AEO 2705) that is separated by approximately 5.4 % from a BIN containing Te. dentata sequences from France and Switzerland ( BOLD: AEE 2533), and an additional BIN is formed for German and Hungarian sequences of Te. dentata ( BOLD: ABA 8838). A final BIN was assigned to specimens from Kyrgyzstan that may belong to Te. dentata ( BOLD: AAI 0670). Work is ongoing to understand genetic variation in this nominally widespread host species (VL and P. Biella, unpublished data).

Distribution.

Morocco, Algeria, Egypt, Spain, France, Germany, Switzerland, Italy, Austria, Hungary, Czechia, Slovakia, Poland, Slovenia, Croatia, Serbia, Albania, North Macedonia, Romania, Bulgaria, Greece, Moldova *, Ukraine, Belarus, Russia (European part), Turkey, Georgia, Azerbaijan, Israel, Syria, Kuwait, Iran, Tajikistan, Kyrgyzstan * ( de Beaumont 1940; Lieftinck 1968; Kuhlmann et al. 2014; Ascher and Pickering 2025; Fig. 10 View Figure 10 ).