In this paper, a new species belonging to the Andrena pilipes/nigrospina complex, Andrena culucciae sp. nov., is described and illustrated from northern Sardinia (Italy). The species is distinguished by significant morphological characters, including the structure of the genital capsule and the translucent marginal zones of the tergites in males, as well as the coloration patterns of setae in females. These characters are discussed in detail and compared with those of closely related species. Morphological evidence is complemented by COI barcode data, which supports the distinctiveness of the new taxon, although they do not fully resolve the phylogenetic relationships within the A. pilipes/nigrospina complex. Both Neighbor-Joining and Maximum Likelihood trees consistently place A. culucciae sp. nov. in a well-supported monophyletic clade. The COI data also reveal p-distance values between A. culucciae sp. nov. and both A. nigrospina Thomson, 1872 and A. pilipes Fabricius, 1781 that are higher than those observed between A. nigrospina and A. pilipes themselves, and show distinct haplotypes for all three taxa. Furthermore, we argue that the Sardinian subspecies Andrena pilipes iliensis Alfken, 1938 is not valid, as it lacks significant morphological and molecular divergence from A. pilipes s.s. An identification key for the Andrena pilipes/nigrospina complex is provided. Ecological data on A. culucciae sp. nov. are also presented, suggesting a possible association with coastal dune habitats. This highlights important conservation implications, given the ecological vulnerability of these environments in the Mediterranean region.

Andrena culucciae, Apoidea Anthophila, Culuccia Peninsula, DNA barcoding, Mediterranean, molecular analysis, Scanning Electron Microscope, synonym, wild bees

Wild bees are one of the most important and diverse groups of pollinators, with over 20,000 species worldwide (Michener 2007). Italy hosts a rich bee fauna, with approximately 1000 species (Lhomme et al. 2020; Reverté and Miličić et al. 2023), as it lies within the Mediterranean basin, a recognized global hotspot for bee diversity (Orr et al. 2021). Although knowledge of wild bees in Italy is incomplete, recent studies are improving our understanding of their local distribution at the national level (e.g. Cornalba et al. 2024; Fortini et al. 2024; Goglia et al. 2024; Zanini et al. 2025). In particular, new records and species for science have recently been reported from Sardinia (e.g. Catania et al. 2021; Nobile et al. 2021; Praz et al. 2022; Annessi et al. 2025a), the second largest island in the Mediterranean, which hosts many distinctive species, including endemic taxa shared with Corsica or other regions, as well as several species with a very restricted distributions (Grill et al. 2007).

The genus Andrena Fabricius, 1775 is a very species-rich genus that currently contains approximately 1,738 species worldwide (Wood 2025), divided into 101 subgenera according to Dubitzky et al. (2010), but a recent revised classification of Pisanty et al. (2022) suggested around 130 subgenera. The count of species known from Italy has fluctuated over time, with 173 species listed by Pagliano (1994), 234 by Comba (2019) and 218 by Wood et al. (2023). Within Andrena, the subgenus Plastandrena, established by Hedicke (1933), comprises 33 valid species worldwide according to Michener (2007), to which three additional species previously assigned to the subgenus Agandrena, recently synonymised with Plastandrena (Pisanty et al. 2022), should now be added. Plastandrena is mainly recognisable by the hind tibial spur, which is clearly broadened at its base combined with the rugose areolate propodeal triangle, rounded pronotum, black male face (never with yellow maculations), and coarsely (not minutely and finely) punctate terga (Pisanty et al. 2022).

Among species of this subgenus, the taxonomic status of the Andrena pilipes/nigrospina complex is confused and has been extensively debated (Wood 2023a). Since the 19^th century, several authors have described some forms in this complex from different geographical areas under different names, which have been synonymised with two closely related species: Andrena pilipes Fabricius, 1781 and Andrena nigrospina Thomson, 1872 (see Baker 1994, 2000; Schmid-Egger and Patiny 1997; Gusenleitner and Schwarz 2002). The former is a bivoltine taxon (March-April; July-August) with narrow penis valves, whereas the latter is a univoltine taxon (May-June) with basally broad penis valves (Schmid-Egger and Patiny 1997; Wood 2023a). According to Baker (2000) and Wood (2023a), the species can only be distinguished by examining the genital capsule of the male, whereas female specimens cannot be reliably distinguished morphologically due to variations in the colour of the pubescence between generations or species. The genetic separation of these two species has been challenging due to the lack of confidently identified material (Schmidt et al. 2015). However, Wood (2023a,b) found genetic support for these taxa by the analysis of new genetic sequences from different geographic regions and from phenological data: each clade showed low intraspecific variation (0.00–0.37% for A. pilipes, 0.00–1.06% for A. nigrospina), while variation between the two clades ranged from 1.06% to 2.35%, with an average of 1.63%. Although the overall absolute range extent of these two taxa is not fully defined, A. nigrospina has a distribution through more temperate regions and is found in Austria, Belgium, France, Finland, Germany, Hungary, Ireland, Kyrgyzstan, Poland, Turkey, Spain and the United Kingdom, while A. pilipes is more thermophilic and has a more southerly distribution, dominating in the Mediterranean basin (including Italy) and extending into Central Asia to China (Wood 2023a). In addition, Alfken (1938) described the subspecies Andrena pilipes iliensis from Sardinia, characterized by small size, black scopa and more finely punctate mesonotum and terga. However, the existence of this subspecies is controversial, as it appears to be a morphological variation induced by the climatic conditions of southern regions, since individuals with black scopa have also been found in Corsica, Sicily, Morocco, southern Greece, and Crete (Grünwaldt 1976; Baker 1994; Schmid-Egger and Patiny 1997).

During a recent survey of flower visiting insects on the Culuccia peninsula (northern Sardinia, Italy) (Annessi et al. 2025a,b), we found a new Andrena species of the A. pilipes/nigrospina complex, which shows morphological and molecular differences from the currently known related taxa. In this paper, we describe this new taxon and discuss its affinities with the closest species. Moreover, we suggest that the Sardinian subspecies Andrena pilipes iliensis is not valid, as it shows no significant morphological and molecular differences from A. pilipes s.s.

Field observations on Andrena culucciae sp. nov. were carried out in the Culuccia Peninsula (northern Sardinia) between May and June 2022–2024 (Fig. 1). The peninsula, which covers approximately 300 hectares, is situated at an altitude of 0–93 m above sea level and is mainly characterized by Mediterranean scrub, followed by transitional woodland/shrub and a mosaic of other environments including wetlands, herbaceous dunes, bare rock, pasture, garigue, beach and vineyards (Annessi et al. 2025b). Bees were collected using nets between 10 am and 4 pm. Each individual was assigned a unique identification code, collection date, WGS84 coordinates, environmental type and the plant species on which it was observed. Specimens were euthanized by freezing at –20 °C for subsequent DNA analysis, then stored dry in entomological boxes and preserved at the Museum of Zoology and Comparative Anatomy, Department of Science, Roma Tre University (Rome, Italy).

Figure 1. 

Position of the study area in Sardinia and in Italy (A). Satellite image of the Culuccia Peninsula (B), base map: orthophoto © 2024 Google.

Total genomic DNA was extracted from one leg of eight specimens (one male and seven females) using the salting out protocol (Sambrook et al. 1989), eluted in 100 μL H₂O milliq and stored at -20 °C. The barcode fragment of mitochondrial Cytochrome C Oxidase subunit I gene was amplified using the primer pair LCO1490 (5’-GGTCAACAAATCATAAAGATATTG-3’) and HCO2198 (5’ TAAACTTCAGGTGACCAAAATCA-3’) (Folmer et al. 1994). For each PCR, an aliquot of 1 μL of DNA and 24 μL of reaction mixture (MIX) were used. The MIX contained: 3 μl of Buffer 10×, 1 μl MgCl2 50 mM, 0.5 μl dNTPs 10 mM, 0.5 μl primer forward 10 mM, 0.5 μl primer reverse 10 mM, 0.5 μl BSA, 0.2 Taq DNA polymerase 5U/μl and 17.8 H2O milliQ. The PCR cycling conditions were based on Marconi et al. (2022). To verify amplification success, 3 μL of PCR product were run on a 1% agarose gel stained with 1 μL of Midori Green (Nippon Genetics Europe). Successfully amplified products were then purified and sequenced by Macrogen (Milan, Italy).

COI sequences were edited with Geneious Prime ver. 2023.1.2 (https://www.geneious.com) and aligned using MUSCLE (Edgar 2004) in MEGA 12 (Kumar et al. 2024), together with sequences of other Plastandrena species from the Western Palaearctic and three sequences each of Andrena flavipes Panzer, 1799, Andrena thoracica (Fabricius, 1775), Panurgus corsicus Warncke, 1972 and Panurgus canescens Latreille, 1811, used as outgroups, all downloaded from BOLD (Suppl. material 1). The resulting alignment was used to build a consensus Neighbor-Joining (NJ) phylogenetic tree in MEGA 12 (1000 bootstrap replicates (BS); K2P model) and a Maximum Likelihood (ML) tree with IQ-TREE web (Trifinopoulos et al. 2016). For ML inference, the best substitution model was selected with ModelFinder (Kalyaanamoorthy et al. 2017) and the tree search was carried out setting the number of unsuccessful iterations to 1000. Node support was estimated by applying 1000 replicates of ultrafast bootstrap (UFBboot2; Hoang et al. 2018) and Shimodaira-Hasegawa (SH)-like approximate ratio tests (SH-aLRT; Guindon et al. 2010). To explore the genetic diversity within the pilipes/nigrospina species complex a distance matrix for the species A. pilipes, A. nigrospina and A. culucciae sp. nov. was built with MEGA 12 using the p-distance model (Srivathsan and Meier 2012) and a haplotype network was produced using TCS v 1.21 (Clement et al. 2000). The network was visualized in TcsBU (Múrias dos Santos et al. 2016). The Andrena culucciae sp. nov. sequences were deposited in BOLD and GenBank under Acc. n° PX058884–PX058891.

To morphologically compare the new taxon with the closely related taxa, comprehensive data from the literature was consulted (e.g. Baker 1994; Schmid-Egger and Patiny 1997; Gusenleitner and Schwarz 2002; Wood 2023a,b). In addition, material from the wild bee collections deposited at the “Museum of Zoology and Comparative Anatomy” of Roma Tre University (Rome, Italy) and at the “Museum of Zoology” of La Sapienza University of Rome (Rome, Italy), was examined (Table 1). Acronyms for the collectors, identifiers and depositories are as follows: ADG Andrea Di Giulio; AR Alessandra Riccieri; DL Diana Lucente; ER Enrico Ruzzier; LF Lorenzo Fortini; MA Matteo Annessi; MMA Marilena Marconi; MME Maurizio Mei; GP Guido Pagliano; MZUR3 “Museum of Zoology and Comparative Anatomy”, Department of Science, Roma Tre University (Rome, Italy); MZUR “Museum of Zoology” of La Sapienza University of Rome (Rome, Italy).

Photographs were taken with Visionary Digital LK Lab System (Visionary Digital, Palmyra, VA) equipped with a Canon EOS 6D mark II dSLR camera and an MP-E 65 mm f/2.8 1–5× lens (Canon, Tokyo, Japan). This device automatically captured stacks of images taken at different focal planes and combined them using Helicon Focus 7 software. SEM images were obtained using a FIB/SEM Helios 5 CX DualBeam (Thermo Scientific, Brno, Czech Republic) at the LIME (Electron Microscopy Interdepartmental Laboratory, Rome, Italy) of Roma Tre University.

Morphological terms follow Michener (2007). The following abbreviations are used in the species description: A = antennal segments (counting from the scape), S = metasomal sterna, T = metasomal terga. The nomenclature is in accordance with Kuhlmann et al. (2018) and Ghisbain et al. (2023), while the systematic framework reported in Hymenoptera: Apoidea: Anthophila of Italy by Comba (2019) was followed for the subspecies Andrena pilipes iliensis.

Genus Andrena Fabricius, 1775

Subgenus Plastandrena Hedicke (1933)

 Andrena culucciae Annessi, Riccieri & Di Giulio, sp. nov

https://zoobank.org/8521C5B4-D4F7-474A-A1CC-8E6CEB6C99E1

Material examined.

Italy Sardinia, Culuccia Peninsula (Sassari Province) Holotype: • 1 ♂; 41.194361°N, 9.288000°E; 18 May 2024; ADG & MA leg.; entomological nets; on Armeria pungens (Link) Hoffmanns. & Link (Plumbaginaceae) in herbaceous dune vegetation; MZUR3. Paratypes: • 1 ♀; 41.199972°N, 9.292444°E; 17 May 2022; ADG & MA leg.; entomological nets; on Cistus monspeliensis L. (Cistaceae) in Mediterranean maquis; GenBank: PX058890; MZUR3. • 3 ♀; 41.194361°N, 9.288000°E; 18 May 2022; ADG & MA leg.; entomological nets; on Echium plantagineum L. and Jasione montana L. (Campanulaceae) in herbaceous dune vegetation; GenBank: PX058884; MZUR3. • 1 ♀; 41.203083°N, 9.290833°E; 01 Jun 2023; ADG & MA leg.; entomological nets; on Bunias erucago L. (Brassicaceae) in pasture; MZUR3. • 2 ♀; 41.194361°N, 9.288000°E; 01 June 2023; ADG & MA leg.; entomological nets; on Armeria pungens (Link) Hoffmanns. & Link (Plumbaginaceae) in herbaceous dune vegetation; MZUR3. • 37 ♀, 1 ♂; 41.194361°N, 9.288000°E; 18 May 2024; ADG & MA leg.; entomological nets; on Armeria pungens (Link) Hoffmanns. & Link (Plumbaginaceae) in herbaceous dune vegetation; GenBank: PX058885, PX058886, PX058887, PX058888, PX058889, PX058891; MZUR3.

Molecular evidence.

The eight COI sequences obtained from our specimens had a total length of 570 bp and were monophyletic, with high support both in the NJ tree (bootstrap = 99) and in the ML tree (UFB = 99; SH-aLRT = 98.4) (Figs 2, 3). The phylogenetic relationships among A. nigrospina, A. pilipes and A. culucciae were clearer in the NJ tree, where A. culucciae forms a clade that is sister to A. pilipes + A. nigrospina (Fig. 2). In contrast, the ML tree does not recover A. nigrospina as a monophyletic group, preventing the resolution of relationships among the three taxa, even though A. culucciae emerges as an isolated and well-defined clade denoting genetic differentiation from A. nigrospina and A. pilipes (Fig. 3). P-distance values were as follows: A. culucciae vs A. nigrospina = 1.64%; A. culucciae vs A. pilipes = 1.74%; A. pilipes vs A. nigrospina = 1.01%. Relationships among haplotypes in the haplotype network (Fig. 4) were coherent with those emerging from the NJ and with the p-distance values. 16 haplotypes were detected: nine belonging to Andrena pilipes, one of which is shared with the subspecies A. pilipes f. iliensis; five belonging to A. nigrospina; and three belonging to A. culucciae.

Figure 2. 

Neighbor Joining Tree based on the COI highlighting the relationship between Andrena pilipes, A. nigrospina and A. culucciae sp. nov. within the context of the Western Palearctic Plastandrena. Numbers at nodes indicate bootstrap values; only values above 70 are represented.

Figure 3. 

Maximum Likelihood Tree based on the COI highlighting the relationship between Andrena pilipes, A. nigrospina and A. culucciae sp. nov. within the context of the Western Palearctic Plastandrena. Numbers at nodes indicate SH-aLRT/UFB values; only values of SH-aLRT above 80 and of UFB above 95 are reported.

Figure 4. 

Haplotype network of A. pilipes, A. nigrospina and A. culucciae sp. nov. Colours assigned to each taxon are reported in the legend. Not sampled intermediate haplotypes are indicated by white dots.

Diagnosis.

The new species Andrena culucciae can easily be recognized as a Plastandrena due to its distinctly widened and curved hind tibial spur at the base, the rugose areolate propodeal triangle, the rounded pronotum and coarsely punctate terga. It is structurally very similar to the other taxa within the A. pilipes/nigrospina complex because of its large size, dark body, dense network of raised rugosity on the dorsolateral faces of the propodeum and clypeus with large and dense punctations. Andrena culucciae differs mainly from Andrena pilipes s.s. and A. pilipes f. iliensis in the male sex by a longer genital capsule and broader penis valves at the base (Figs 5–7), as well as the translucent marginal zones of T2-T5 (Fig. 8), which also distinguishes it from A. nigrospina. Females can be distinguished based on the predominant coloration of the setae on the hind legs: in A. culucciae, the setae on the femur are white and the tibial scopa is brown, in A. pilipes f. iliensis both femoral setae and tibial scopa are black, while in A. pilipes and in A. nigrospina both are white (Fig. 9). Further morphological comparisons between A. culucciae, A. pilipes and A. pilipes f. iliensis are reported in Table 2.

Table 2.

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Morphological differences between Andrena culucciae sp. nov., A. pilipes f. iliensis and A. pilipes s.s. *As no information is available in the literature, the measurements only refer to the characters of the material examined (see Table 1).

	Andrena culucciae sp. nov.	A. pilipes f. iliensis	Andrena pilipes s.s.
Male
1) dimension	12–13 mm	11 mm*	13–15 mm
2) setae on face and vertex	whitish and brownish	dark brown and black	dark brown and black
3) length of A4 compared to A3	≈ 1	≈ 1,15*	≈ 1,20*
4) setae on mesosoma	whitish, brownish and greyish	brown and black	brown and black
5) marginal zones of T2-T5	translucent (Fig. 8A)	dark (Fig. 8B)	dark (Fig. 8C)
6) maximum width of penis valves (mm)	0,36–0,38	0,26*	0,25–0,27*
7) apex of penis valves	slender	inflated	inflated
8) cuspis (volsella)	triangular and spatulate, with a rounded apex (Fig. 11A,C)	–	short and slender, apically pointed and slightly curved (Fig. 11B,D)
Female
1) dimension	14–16 mm	12–14 mm	14–16 mm
2) setae on face and the vertex	brown	black	black
3) fovea	brown	black	black
4) setae on hind femur	white (Fig. 9A)	black (Fig. 9B)	white (Fig. 9C)
5) tibial scopa	brown (Fig. 9A)	black (Fig. 9B)	white (Fig. 9C)

Figure 5. 

Dorsal view of male genitalia A Andrena culucciae sp. nov. B Andrena pilipes f. iliensis C Andrena pilipes s.s. Scale bars: 1 mm.

Figure 6. 

SEM images of the dorsal view of male genitalia A Andrena culucciae sp. nov. B Andrena pilipes s.s. Scale bars: 0,5 mm.

Figure 7. 

Dissected genital capsule of A Andrena culucciae sp. nov. B Andrena pilipes s.s. From top to bottom: gonocoxae and gonostyli, penis valves and volsella. Scale bars: 1 mm.

Figure 8. 

Dorsal view of male tergita A Andrena culucciae sp. nov. B Andrena pilipes f. iliensis C Andrena pilipes s.s. Scale bars: 1 mm.

Figure 9. 

Hind legs of female A Andrena culucciae sp. nov. B Andrena pilipes f. iliensis C Andrena pilipes s.s. Scale bars: 1 mm.

Description.

Male (Fig. 10). Body length: 12–13 mm. Head. Black, 1.2 times wider than long (Fig. 10B). Ocelloccipital distance slightly greater than lateral ocellar diameter. Paraocular areas depressed, both frons and paraocular areas with longitudinal wrinkles (Fig. 10B). Clypeus domed, slightly shiny with dense and large punctures, without an impunctate central line (Fig. 10B). Labral process trapezoidal, apex emarginate. Mandibles slightly crossing apically with sparse setae along outer margin, bidentate; apical tooth longer than preapical tooth; maxillary palpi with six segments, labial palpi with four segments. Gena moderately broad, about equal in width to compound eye. Vertex and face with whitish and brownish setae (Fig. 10B). Antenna dark, A3 slightly shorter than A4 (Fig. 10B). Mesosoma. Scutum and scutellum irregularly punctate, with punctures larger and sparser medially. Pronotum rounded laterally, without humeral angle. Episternum and lateral propodeal surface reticulate, propodeal triangle strongly carinate with internal surface rugose-areolate. Scutum and scutellum with moderately long whitish setae, episternum and propodeum with brownish setae (Fig. 10A). Legs dark, tarsal claw light brown, general pubescence dark brown, lighter on tarsal segments (Fig. 10A, C). Wings brownish, venation dark brown and stigma light brown and nervulus slightly antefurcal; tegulae brown with surface rugose (Fig. 10A). Metasoma. Terga dark and regularly punctate, punctures separated on average by 2 puncture diameters (Fig. 10A). Disc of T1 with sparser punctation, marginal zones of T2-T5 slightly depressed and translucent (Fig. 10A). T1-T4 with very sparse short brown setae, last tergites with longer and darker hairs. Pygidial plate absent. S7 deeply emarginate apically with lateral lobes hairy. S8 hairy, slightly emarginate apically (Fig. 10F). Genitalia elongate, gonocoxae with clearly produced apical teeth, these diverging slightly; gonostyli with apical spatulate parts elongate and parallel margins (Figs 6A, 7A, 10D, E). Penis valves broad at the base (Figs 6A, 7A, 10D), progressively tapering to the apex (Fig. 7A). Volsella transverse, with rounded outer margins, and with both cuspis and digitus well developed (Figs 7A, 11A). Digitus curved, subparallel to the cuspis, basoventrally fused with the basivolsella, and with a bulged apex (Figs 7A, 11A, C). Cuspis triangular and spatulate, with a rounded apex and numerous erect setae of different lengths (Fig. 11C). Cuneiform tooth-like cuticular structure, obliquely truncate and laterally directed, located in the ventral apical part of the digitus and the dorsal subapical part of the cuspis (Fig. 11C). Basivolsella bulged, with numerous elongate setae (approximately 20, Fig. 11A).

Figure 10. 

Andrena culucciae sp. nov. male A dorsal view B head C lateral view D genitalia dorsal view E genitalia profile F sternite 8. Scale bars: 5 mm (A); 2 mm (B, C); 1 mm (D–F)

Figure 11. 

SEM images of the lateral view of the volsella of (A, C) Andrena culucciae sp. nov. and (B, D) Andrena pilipes s.s. (A, B) general view; (C, D) details of the apex of the cuspis and the digitus. Scale bars: 0,2 mm (A, B); 0,05 mm (C, D).

Female (Fig. 12). Body length: 14–16 mm. Head. Black, 1.2 times wider than long (Fig. 12B). Ocelloccipital distance slightly greater than lateral ocellar diameter. Fovea uniformly depressed along entire length, with lower margin ending distinctly below antennal insertion (Fig. 12B). Frons with longitudinal wrinkles (Fig. 12B). Clypeus, gena, maxillary and labial palpi as in male, labral process trapezoidal but without apical emargination. Mandibles slightly crossing apically with sparse setae along outer margin, unidentate. Subgenal coronet present and well-developed. Fovea, vertex and face with brown setae (Fig. 12B). Antenna dark, A3 slightly exceeds A4+5, shorter than A4+5+6 (Fig. 12B). Mesosoma. Scutum, scutellum, pronotum, episternum, propodeum and propodeal triangle as in male. Scutum and scutellum with moderately long black and dark brown setae, episternum and propodeum with brownish setae (Fig. 12A). Propodeal corbicula incomplete, possessing only a dorsal fringe; internal surface mostly glabrous, with very sparse setae. Legs dark, with tarsal claw light brown; fore and middle legs with general pubescence dark brown, lighter on tarsal segments; hind legs with white hairs on femur and tibial scopa predominantly composed of brown hairs (Figs 9A, 12A, C). Wings and tegulae as in male but browner (Fig. 12A). Metasoma. Terga entirely dark, punctation similar to that of the male (Fig. 12A). Pubescence of T1-T4 as in male, apical fringe of T5 and hairs flanking pygidial plate dark brown (Fig. 12A). Pygidial plate V-shaped with round apex and a distinct raised internal triangle; internal surface rough.

Figure 12. 

Andrena culucciae sp. nov. female A dorsal view B head C lateral view. Scale bars: 5 mm (A); 2 mm (B, C)

Derivatio nominis.

We named the new species after Culuccia Peninsula (Sardinia, SS, Italy), where the specimens were collected.

Distribution.

Sardinia (Italy).

Ecological aspects.

Specimens of Andrena culucciae sp. nov. were mainly observed on Armeria pungens (Plumbaginaceae) in the herbaceous vegetation of coastal dunes with coarse sand (Fig. 13). However, this new taxon was also recorded on plant species belonging to different families, such as Boraginaceae, Brassicaceae, Campanulaceae and Cistaceae. These observations suggest that A. culucciae sp. nov. is polylectic, like its closest related taxa (Beil et al. 2008).

Figure 13. 

Herbaceous dune vegetation in the Culuccia Peninsula (Sardinia, Italy), where most of the Andrena culucciae sp. nov. specimens were collected (A) Female of Andrena culucciae sp. nov. on Armeria pungens (B) (Photos by M. Annessi).

In this study, we describe a new species within the Andrena pilipes/nigrospina complex. The new species is supported by several diagnostic morphological characters. In particular, the structure of the genital capsule and the translucent marginal zones of the tergites enable reliable identification of male individuals. Moreover, females of A. culucciae sp. nov. exhibit distinct and unambiguous coloration patterns of setae, in contrast to A. pilipes and A. nigrospina, whose females cannot be reliably separated based on pubescence color (Wood 2023a).

COI data is not conflicting with the morphological evidence, but they are not sufficient to resolve the relationships within the Andrena pilipes/nigrospina complex and to clearly delimit the three species. This is not surprising in this group (Wood 2023b) or in other insects (e.g. in Orthoptera: Hochkirch et al. 2024; Nabholz et al. 2024; in beetles: Poloni et al. 2023; Riccieri et al. 2024), and the application of more advanced genetic techniques would be particularly beneficial, especially in cases where greater ambiguity exists between morphological data and standard barcodes. However, here we combined significant morphological evidences with molecular results that still point to the uniqueness of our specimens: they consistently form a well-supported, isolated clade in both phylogenetic trees (Figs 2, 3); the p-distances between A. culucciae and both A. nigrospina and A. pilipes (1.64% and 1.74%) are greater than that between A. nigrospina and A. pilipes (1.01%); and the haplotype network shows clear genetic separation among the three species’ haplotypes.

Phenological observations also support the distinction between the new species and the syntopic A. pilipes. Andrena culucciae sp. nov. was observed only in May and early June, suggesting a univoltine life cycle, with a flight period that does not overlap with that of A. pilipes, which occurs in early spring and summer. This suggests that A. culucciae sp. nov. has flight patterns more similar to A. nigrospina, the univoltine species absent in Italy, which also flies in May and June. This hypothesis is supported by the comprehensive survey of wild bees conducted on the Culuccia Peninsula (Annessi et al. 2025a), in which A. pilipes f. iliensis was recorded in April without overlapping with the new taxon.

It is worth notice that Andrena pilipes f. iliensis specimens were completely nested within the clade of A. pilipes s.s. in the NJ and ML trees (Figs 2, 3) and shared the same haplotype with other specimens of A. pilipes s.s. (Fig. 4). Moreover, this subspecies shows no significant morphological differences from A. pilipes s.s., except for smaller body size and the black scopa, which could be attributed to “warm forms” occurring in warmer regions (Baker 1994; Grünwaldt 1976). According to these results and observations, we suggest that Andrena pilipes iliensis is not a valid subspecies, but rather an insular form adapted to a restricted habitat due to its small dimensions, as hypothesized by Baker (1994).

Finally, more observations and molecular studies could confirm the distribution of this new taxon, which could be endemic to Sardinia, or Sardinia-Corsica, but also present in other areas of the Mediterranean. Further studies are needed to investigate the association of Andrena culucciae sp. nov. with coastal dune habitats, as this could have important implications for the conservation of the species, given the high vulnerability of these environments in the Mediterranean region (Zivkovic et al. 2017).

Our sincere thanks to Stella Lin Hung, Marco Boglione, Sabrina Rossi and the staff of the BIRU S.R.L. Agricola for the support provided in hosting and logistics, as well as the economic support granted through the agreement established in 2022 between the Department of Science (Roma Tre University) and the "Osservatorio Naturalistico dell'Isola di Culuccia". The field activities were supported by the invaluable help of Paolo Mariottini, Stefano Cantone, Tommaso Fusco, Francesca Casale, Lorenzo Fortini and Francesco Forte. Finally, we are sincerely grateful to Pierfilippo Cerretti and Maurizio Mei for giving us access to the materials in the collection deposited at the ‘Museum of Zoology’ at Sapienza University in Rome, and to Maurizio Muzzi for his assistance in preparing the plates. This study was supported by the University Roma Tre, Department of Science (grants of Departments of Excellence—L. 232/2016—art.1, commi 314–337 awarded to Dept. of Science—University Roma Tre—Rome—Italy for 2018–2022, and grants 2023–2027). ADG and AR acknowledge the support of NBFC to University of Roma Tre, Department of Science. Funder: Project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4 - Call for tender No. 3138 of 16 December 2021, rectified by Decree n.3175 of 18 December 2021 of Italian Ministry of University and Research funded by the European Union – NextGenerationEU; Award Number: Project code CN_00000033, Concession Decree No. 1034 of 17 June 2022 adopted by the Italian Ministry of University and Research, CUP F83C22000730006, Project title “National Biodiversity Future Center - NBFC”.