Megachile (Hackeriapis) lucifer (Hymenoptera, Megachilidae), a new megachilid with demon-like horns that visits the Critically Endangered Marianthus aquilonaris (Pittosporaceae)

Megachile (Hackeriapis) lucifer (Hymenoptera, Megachilidae), a new megachilid with demon-like horns that visits the Critically Endangered Marianthus aquilonaris (Pittosporaceae) Kit S. Prendergast1,2, Joshua W. Campbell3 1School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, Perth, Western Australia, 6102, Australia 2Centre for Sustainable Agricultural System, University of Southern Queensland, 487-535 West St, Darling Heights QLD 4350, Toowoomba, Australia 3US Department of Agriculture, Agricultural Research Service, Northern Plains Agricultural Research Laboratory, Sidney, Montana, USA Corresponding author: Kit S. Prendergast ([email protected]) Academic editor: Jack Neff|Received 23 July 2025|Accepted 6 October 2025|Published 11 November 2025 https://zoobank.org/AB5C28C9-628A-4CF2-93EA-050D302FC758 Citation: Prendergast KS, Campbell JW (2025) Megachile (Hackeriapis) lucifer (Hymenoptera, Megachilidae), a new megachilid with demon-like horns that visits the Critically Endangered Marianthus aquilonaris (Pittosporaceae). Journal of Hymenoptera Research 98: 1017–1030. https://doi.org/10.3897/jhr.98.166350 Abstract A new species Megachile (Hackeriapis) lucifer (Hymenoptera: Megachilidae) is described from both sexes. Megachile lucifer sp. nov. is of conservation importance, as it is a visitor to the range-restricted, Critically Endangered flowering plant species Marianthus aquilonaris (Pittosporaceae). This new Megachile has yet to be collected outside the region in which this rare plant occurs. A diagnostic feature of Megachile lucifer is the presence of a large pair of outward and upwardly facing, convex horns on each side of the clypeus, which is deeply recessed and features a medial ridge. These horns are found only in the female, unlike most sex-specific weaponry or ornamentation in animals. Clypeal modifications occur in a number of female megachilids which may be related to nest construction, whilst other clypeal horns are found in Hackeriapis females. The description of this new species provides the opportunity for future research into their function, and evolution among this subgenus. DNA barcoding with the CO1 gene confirmed the sexes belonged to the same species and it did not match any previously barcoded species. The species was collected only during mass-flowering of another host, Eucalyptus livida (Myrtaceae). The limited known distribution, and short activity season of this species, along with being associated with a Critically Endangered plant species in a region subjected to mining, suggested it may be a species of conservation concern. JHR 98: 1017–1030 (2025) doi: 10.3897/jhr.98.166350 https://jhr.pensoft.net Copyright: This is an open access article distributed under the terms of the CC0 Public Domain Dedication. RESEARCH ARTICLE Kit S. Prendergast & Joshua W. Campbell / Journal of Hymenoptera Research 98: 1017–1030 (2025) 1018 Keywords Australia, DNA barcoding, Megachilidae, new species, pollinators, threatened species Introduction Australia is facing a pollination crisis, with related crises relating to a lack of information on the pollinators of plants, and the taxonomic impediment (Pyke et al. 2023). For many critically endangered plants, their visitors are unknown, jeopardising our ability to conserve their populations (Prendergast 2010). The Australian native bee fauna is also threatened by a lack of monitoring, and many regions have not been surveyed, whilst many native bees remain undescribed (Taxonomy Australia 2020). This is clearly demonstrated by the Australian Megachilidae. A recent revision of the subgenus Austrochile (Michener, 1965) resulted in 71 new species being described, as well as synonyms being revealed, and changes to taxonomic placement of species being made (Leijs et al. 2025). Hackeriapis was erected by Cockerell in 1922. There are currently 17 described species in Australia (Australian Fauna Directory 2025). An interesting feature of this subgenus is that some of the females have projections on the clypeus (King 1994). Here, we describe a new species of Megachile (Hackeriapis) from both sexes, where the female has highly distinctive, prominent horns on the clypeus, which is deeply depressed with a medial ridge. This species was recorded to be a visitor of Marianthus aquilonaris N.Gibson & Wege (Pittosporaceae), which occurs only in the Bremer Ranges of Western Australia (Prendergast 2019), and is listed Critically Endangered following IUCN criteria on the Western Australian Biodiversity Conservation Act (Department of Biodiversity Conservation and Attractions 2025). By describing this species, we hope to promote greater research into the conservation of this new species, which may be important in turn for the conservation of this range-restricted plant that is threatened with extinction. Materials and methods Specimens involved in the description were collected by K.S. Prendergast with an entomological sweep net (bag mesh size 0.9 × 0.3 mm) during a survey conducted from November 2nd – 4th, 2019, to sample pollinators around populations of Marianthus aquilonaris (Pittosporaceae) on behalf of Botanica Consulting for Audalia Resources. Prior to these surveys, there had been no insect surveys in the region, nor had the visitors to this critically endangered plant been determined. Standard melittological terminology is used to describe the morphology (Michener, 2007). The following standard acronyms are used (following Michener (2007) and King (1994): HL head length; HW head width; AOD antennocular distance; IAD interantennal distance; OOD ocellocular distance; OAD ocelloantennal distance; IOD inter-ocellar distance; ITS intertegular span; LID lower interocular distance; UID upper interocular distance; metasomal sterna and terga are denoted S[segment number] New ‘horned’ Megachile species visiting threatened plant 1019 and T[segment number], flagellomeres are denoted F, teeth on the mandible are denoted Te, with Te1 being the most basal. Measurements are given in millimetres. Specimens were observed with a Leica M205 C stereomicroscope. Measurements and images of key features were made on high-resolution images taken with the same stereomicroscope and using the Passport II imaging system, by Visionary Digital and a camera mounted on the microscope (Canon 7D Mark II), with a 100 mm macro lens, and the Helicon image stacking software. Measurement and scales bars were calibrated (by Visionary Digital) by lens and focal length, and these calibrations uploaded to Photoshop. Description and measurements were made on the female holotype and male paratype. A subsample of the hind femur from a female paratype, and male allotype, were submitted to BOLD (Barcode of Life Database) for DNA barcoding using the cytochrome c oxidase subunit 1 (CO1) gene. The DNA barcode sequence, and other specimen information associated, can be accessed in BOLD via: as part of the Australasian and Pacific bee fauna Project (MSAPB): http://www.boldsystems.org/index.php/ MAS_Management_DataConsole?codes=MSAPB. See also Suppl. material 2. The sequences were obtained from Canadian Centre for DNA Barcoding (CCDB) at the University of Guelph, Guelph, Ontario, Canada. Standard DNA sequencing protocols were carried out by CCDB (available online at: http://www.ccdb.ca/resources.php ), using the PCR primers LepF1/LepR1. The barcoded vouchers are deposited at the Museum of Western Australia. BOLD delineates molecular operational taxonomic units (MOTUs), which are in concordance with species delineations based on traditional methods (Schmidt et al. 2015), to which a Barcode Index Number (BIN) (Ratnasingham and Hebert 2013) is automatically assigned and incorporated into BOLD. Taxonomy Family Megachilidae Subfamily Megachilinae Genus Megachile Latreille, 1802 Subgenus Hackeriapis Cockerell, 1922 Remarks. Using Michener (2007)’s Key to the Australian and Papuan Subgenera of Megachile, this species is tentatively placed in the subgenus Hackeriapis Cockerell, 1922, on the basis that collected females have the following characteristics in common with Michener’s description: mandible with four teeth, cutting edges absent, metasoma parallel sided, S1 without apical spine, claws without ventral tooth, metasomal integument black, glossa linear, fulvous pubescence confined to apical part of metasoma, and for the male specimen collected, the terga has deep postgradular grooves; pubescence with a grey appearance, fulvous on metasoma, forming metasomal bands; and posterior margin of T6 with four teeth. Kit S. Prendergast & Joshua W. Campbell / Journal of Hymenoptera Research 98: 1017–1030 (2025) 1020 Megachile lucifer sp. nov. https://zoobank.org/B8D8CCFA-CF8B-4B70-B79E-28C85F4156FE Material examined. Type material: Holotype. Australia • 1 ♀, holotype; Western Australia, Lake Johnston; 32.52652E 120.79661S; 4 Nov. 2019; K. S. Prendergast leg.; sweep net Marianthus aquilonaris; KSP code233. WAM E112233. Other material. Allotype. Australia • 1 ♂; Western Australia, Lake Johnston; 32.53081E, 120.7925S; 4 Nov. 2019; K. S. Prendergast leg.; yellow pan-trap; KSP code0261. WAM E112061. Paratypes. • 1 ♀ Western Australia, Lake Johnston, 32.5318E, 120.78531S, 2 Nov. 2019, sweep netting (Eucalyptus livida); • 1 ♀ 3 Nov. 2019, blue bee bowl; • 2 ♀ 4 Nov. 2019, blue bee bowl; • 7 ♀ 4 Nov. 2019, yellow bee bowl; • 2 ♀ Western Australia, Lake Johnston, 32.53081E, 120.7925S, 3.Nov.2019, sweep netting (Eucalyptus livida); • 1 ♀ 4 Nov. 2019, blue bee bowl; • 2 ♀ 4 Nov. 2019, yellow bee bowl; • 1 ♀ 4 Nov. 2019, Western Australia, Lake Johnston, 32.52691E, 120.79694S, sweep netting (Eucalyptus livida); K.S. Prendergast leg. Specimens used by DNA barcoding. BOLD DNA barcode: BOLD:AEJ4534. (WAM E112150); BOLD DNA barcode: BOLD:AEJ4534. (WAM E112061) dx.doi. org/10.5883/DS-MEGMAQ. All specimens are deposited in the Western Australian Museum. Accession numbers are provided in Suppl. material 1. Diagnosis. The female of Megachile lucifer is distinguished from all other species of Hackeriapis by the presence of a pair of upward and outward projecting triangular horns on the sides of the clypeus, with a deeply impressed clypeus featuring a slightly raised medial ridge. The clypeal horns, each measuring 0.9 mm in length, are almost half as long as the head width in profile (Fig. 1a–c). The male is distinguished from other Hackeriapis by the carina of T6 being bilobed, each lobe emarginate. The presence of clypeal processes suggests that Megachile lucifer should be part of King’s “Species-group 2” of Hackeriapis (M. patera King, 1994, M. bicornis King, 1994, M. franki Friese, 1920, M. semicandens Cockerell, 1910, M. monkmani Rayment, 1935), however, unlike King’s “Species-group 2”, the mandible is not deeply emarginate between Te3, Te4, nor is the polished medial plate flat, which according to King’s key would place M. lucifer with “Species-group 1” (King 1994). The clypeal horns of M. lucifer are most similar to M. bicornis and M. patera, however the horns project more upward, there is a medial ridge in the clypeus, and the metasoma is not completely orange. The male of M. lucifer differs from M. bicornis in its metasomal colouration, and each lobe of the carina on T6 is emarginate (the male of M. patera is unknown). Description. Female (Fig. 1): Dimensions: Total body length 9.80 mm, HW 3.56 mm, ITS 2.68 mm. Colouration: Non-metallic black; integument of head black; clypeal horns black; mesosoma black; metasoma black; red-brown border on tergites; legs black, final tarsi brown; wings dusky, semi-opaque with wing veins very dark brown; microtrichia especially dark under radial vein of the marginal cell on the forewing; scape, pedicel, F1 dark brown, remainder brown, mandibles black with red Te1 and Te2. New ‘horned’ Megachile species visiting threatened plant 1021 Pubescence: Long white pubescence on face around antennal sockets covering paraocular area and gena, along underside of mandibles, sides of thorax, and metanotum; dense white hairs on base of mandibles; very sparse fine gold hairs short on scutum, short thick gold hairs along cutting edge of mandibles; short white hairs along legs; posterior hairbands on terga present on T1-4, colour of hair bands white; T1 with thick, dense lateral patch; hairbands on T1 and T4 very short and sparse, hairbands on T2-3 complete and about one-fifth of tergite width; T5–T6 pubescence on orangegold; sparse long white hairs on T1; metasomal scopae cream. Sculpture: Head, mesoscutum, and scutellum with large, deep, close punctures; antennal scape with fine, shallow punctures; propodeal triangle with small, shallow punctures (Fig. 1c); terga with minute, shallow, close punctures. Structure head: face wider than long (1.6×); distinct pair of horns on clypeus, triangular in shape, projecting out and slightly up, with pointed tips rounded at the apex, convex on ocular side, inner face deeply concave medially, clypeus has medial vertical ridge with a small protuberance at the base of the clypeus, strongly depressed, hollowed out and concave on each side of the central ridge and horns (Fig. 1b); supraclypeal area slightly elevated and concave; malar space present; mandibles relatively large, with blunt edges, four teeth (three above the notch in along the preapical margin), distance from Te4 to Te3, is greater than from Te3 to Te2, and length of teeth decreases from Te1 to Te4, preapical margin almost vertical (Fig. 1b); gena ca. 0.4× as wide as compound eye viewed laterally; scape not attaining median ocellus; scape 0.75 mm long, Figure 1. Megachile lucifer sp. nov. female, a lateral view b head, frontal view c dorsal view d ventral view. Kit S. Prendergast & Joshua W. Campbell / Journal of Hymenoptera Research 98: 1017–1030 (2025) 1022 with apex approx. 1.5× broader than base, last five flagellomeres longer than wide, F3-5 equal, pedicel and F1-2 longer than wide; final flagellomere wedge-shaped such that it tapers apically, total length of flagellum (pedicel and flagellomeres) 2.09 mm. Head measurements: HL 2.1 mm; gena width 0.86 mm; clypeus length 0.59 mm; UID 2.5 mm; LID 2.53 mm; IAD 0.92 mm; OOD 0.63 mm; IOD 0.65 mm; AOD 0.67 mm; OAD distance 0.53 mm; malar space 0.08 mm; mandible base length 0.67 mm; mandible length 1.5 mm; UID: LID 0.99; clypeus: HL 0.28. Mesosoma: Propodeal triangle slightly convex, carina weak, almost vertical. Mesosoma measurements: overall mesosoma length 3.54 mm; pronotal collar absent; mesoscutum length 2.28 mm; scutellum length 0.73 mm; mesoscutum length:ITS 1.32; scutellum:mesoscutum 0.32. Legs: tarsal claws simple, no basal claw; hind tibial spurs with small, dense serrations. Metasoma: overall metasoma length 3.54 mm; metasoma longer than mesosoma (metasoma:mesosoma 1.33); T1 width 3.1 mm, anterior face concave, with surface highly declivous; metasoma broadest at T3; T1-4 slightly convex. Male (Fig. 2): Dimensions: Body length 8.9 mm, HW 2.87 mm, ITS 2.6 mm. Colouration: similar to female, except T5-T7 orange, slight brown apical border laterally on T5. Pubescence: Pubescence on face much thicker than female, hairs cover entire head including clypeus; beard of hairs on genae longer (Fig. 2b). Preapical hair bands incomplete. Sculpture: similar to female, except polished impunctate apical bands on T1-5. Structure – head: horns absent, clypeus slightly concave, covered in dense long white hairs, mandibles tridentate. Scape 0.55 mm long, similar in structure to female with final flagellomere wedge-shaped such that it tapers apically, total length of flagellum (pedicel and flagellomeres) 2.01 mm. Head measurements: HL 1.77 mm; gena width 0.7 mm; clypeus length 0.50 mm; UID 1.58 mm; LID 1.74 mm; IAD 0.78 mm; OOD 0.68 mm; IOD 0.56 mm; AOD 0.47 mm; OAD distance 0.53 mm; malar space 0.13 mm; mandible base length 0.51 mm; mandible length 0.86 mm; UID:LID 0.91; clypeus:HL 0.28. Mesosoma: overall mesosoma length 3.50 mm; pronotal collar absent; mesoscutum length 2.04 mm; scutellum length 0.79 mm; mesoscutum length:ITS 1.34; scutellum:mesoscutum 0.39. Structure – legs: tarsal claws with basal tooth (Fig. 2a). Hind-tibial spurs similar to female. Forelegs not modified. Structure metasoma: metasoma longer than mesosoma, less so than female (metasoma:mesosoma 1.29); broadest at second segment, overall metasoma length 3.54 mm; metasoma longer than mesosoma (metasoma:mesosoma 1.33); T1 width 3.02 mm; T1-4 slightly convex; carina of T6 bilobed, each lobe emarginate (Fig. 2b, d). Etymology. The name “lucifer” alludes to the projections on the female clypeus, reminiscent of devil-like horns. It is proposed as a noun in apposition. New ‘horned’ Megachile species visiting threatened plant 1023 Distribution. Bremer Ranges region around Lake Johnston, Coolgardie bioregion of inland southeast Western Australia (Fig. 3). Type-locality. Australia, Western Australia: Bremer Ranges, Lake Johnston; 32.52652E, 120.79661S; habitat type is open woodland with sparse understory on skeletal sandy-loam over laterite, collected with an entomological sweep net, foraging on Marianthus aquilonaris, 4 Nov. 2019, K. Prendergast. Ecology. Months collected: Nov 24 2019. Surveys in the region conducted earlier in October in 2022 and 2024 failed to collect this species. Floral visitation: 1 ♀ Marianthus aquilonaris (Fig. 4a), 3 ♀ Eucalyptus livida Brooker & Hopper (Fig. 4b). Conservation status. To date, the species has only been collected in the Bremer Ranges. Viewing the WA Museum entomology collection additional specimens were not found, nor have other specimens been collected by K.S. Prendergast in surveys across Canarvon, Eighty Mile Beach, Purnululu, Geradlton, across the Swan Coastal Plain or the Jarrah Forest region. No other specimens were found in the OZBOL BOLD database. The Bremer Ranges region is at risk from a number of threatening processes, including gold mining, inappropriate fire regimes, and climate change (Prendergast 2019; Pick 2020; Prendergast 2021). One of the host plants, Marianthus aquilonaris, is Critically Endangered under the Western Australian Biodiversity Conservation Act, as its extent of occurrence is less than 100 km2, its area of occupancy Figure 2. Megachile lucifer sp. nov. male, a lateral view b head, frontal view c dorsal view d ventral view. Kit S. Prendergast & Joshua W. Campbell / Journal of Hymenoptera Research 98: 1017–1030 (2025) 1024 being less than 10 km, and suffers from fragmentation (Hopley and Byrne 2019; Prendergast 2019; Pick 2020; Prendergast 2021). The region where the species has been collected is not currently under any conservation protection. Under the IUCN Red List criteria, criteria A, C and E cannot be assessed as there is no ongoing monitoring; however, based on criteria B: Geographic range in the form of either B1 (extent of occurrence) OR B2 (area of occupancy) OR both, it may be considered to be Critically Endangered (IUCN 2012). However, further surveys in areas with Eucalyptus livida, another host plant, are required to determine if it occurs in other locations within the Coolgardie region where E. livida occurs. DNA barcoding (See also Suppl. material 2). The specimens barcoded were both assigned the BIN BOLD:AEJ4534. The associated Genbank accession numbers are: BankIt2979786 gnl|uoguelph|OZBOL2716-21.COI-5P PV919132 BankIt2979786 gnl|uoguelph|OZBOL2721-21.COI-5P PV919133. No other specimens in BOLD matched the BIN BOLD:AEJ4534 assigned to these specimens. The association of the sexes was confirmed, with only 0.3% distance between the two specimens in this BIN. The distance to the nearest neighbour of M. lucifer is 7.1%, and thus exceeds the cut off of a minimum of 2% distance to be considered a distinct species. The nearest neighbour in BOLD has the BIN BOLD:AEC5722, and is not assigned to a species of Megachile. This species is in turn the nearest neighbour (6.1%) to an undescribed Megachile, BIN BOLD:AGD4390. Figure 3. Map of Australia showing sites where specimens of Megachile lucifer sp. nov. has been collected (see also Supplementary Information. Map produced via MyMaps Google. New ‘horned’ Megachile species visiting threatened plant 1025 Discussion Megachile lucifer is distinctive in the clypeal horns in the female. As the clypeal modifications occur only in the female, rather than the male, it cannot be related to malemale competition (e.g. (Alcock and Houston 1996; Fraberger and Ayasse 2007)). Horn-like clypeal modifications also occur in a number Centris Fabricius, 1804, (Velez and Vivallo 2012), Osmia Pranzer, 1806 (MacIvor et al. 2022), and Megachile Latreille, 1802 (Snelling 1990; King 1994), solely in the female. These cases of independent evolution would suggest they have some adaptive function. It may be that these assist Figure 4. Images of the two host plant species of Megachile lucifer sp. nov., a Marianthus aquilonaris and b Eucalyptus livida. a b