Research Article |
Corresponding author: Mark K. L. Wong ( markwong.research@outlook.com ) Academic editor: Matthew Prebus
© 2024 Mark K. L. Wong, Jane M. McRae.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wong MKL, McRae JM (2024) Leptanilla voldemort sp. nov., a gracile new species of the hypogaeic ant genus Leptanilla (Hymenoptera, Formicidae) from the Pilbara, with a key to Australian Leptanilla. ZooKeys 1197: 171-182. https://doi.org/10.3897/zookeys.1197.114072
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The genus Leptanilla Emery, 1870 of the family Formicidae, subfamily Leptanillinae, comprises miniscule, pale, blind ants that are rarely collected and poorly understood due to their hypogaeic (i.e. underground) lifestyles. Here we describe a new Leptanilla species from two workers collected via subterranean scraping in the arid Pilbara region of Western Australia. Leptanilla voldemort sp. nov. is the second leptanilline species documented in Australia after the elusive Leptanilla swani Wheeler, 1932. Workers of L. voldemort sp. nov. display a remarkably gracile morphology characterised by elongated legs, antennae, and mandibles, and they are easily differentiated from other Leptanilla species. We also provide new measurements for L. swani from two workers found proximally to the type locality of L. voldemort sp. nov. A key to the worker caste of Leptanilla species of the Australian continent is presented.
Australia, hypogaeic, Leptanilla, Milieu Souterrain Superficiel, subterranean
Although lacking the impressive colours, armoury and colony sizes seen in many of the world’s ~14,000 ant species (
The 61 described species of Leptanilla are found in tropical and temperate regions of the Old World (
Here, we describe a new Leptanilla species, Leptanilla voldemort sp. nov., from two workers collected in the arid Pilbara region of Western Australia. Leptanilla voldemort sp. nov. represents the second species of Leptanilla and second member of the subfamily Leptanillinae from the Australian continent. Notably, workers of L. voldemort sp. nov. display a distinctly gracile morphology, characterised by elongated legs, antennae, and mandibles. This remarkable phenotype is not seen in most other Leptanilla species – including the other Australian species, L. swani, for which new morphological measurements are hereby reported from two workers collected proximally to the type locality of L. voldemort sp. nov. A key to the worker caste of Leptanilla from Australia is also presented.
Photographs of specimens were obtained with an incorporated digital camera mounted on a Leica M205C dissecting microscope through the Leica Application Suite V4 software. A total of 33–72 images were taken and stacked together. Morphological measurements and indices were calculated following
HW (head width): maximum width of cranium in full-face view.
HL (head length): maximum length of head in full-face view from anterior margin of head to cranial vertex.
SL (scape length): maximum length of scape in medial view, excluding bulbus.
MaL (mandible length): maximum length of mandible from view orthogonal to lateral mandibular margin, measured from ventral mandibular articulation to mandibular apex.
WL (Weber’s length): maximum diagonal length of mesosoma in profile view, measured from most anterior extent of pronotum excluding cervical shield to most posterior extent of propodeal lobes, when present.
PrW (pronotal width): maximum width of pronotum, measured in dorsal view.
MW (mesonotal width): maximum width of mesonotum in dorsal view, measured immediately anterior to mesocoxal foramen.
PTL (petiolar length): maximum length of petiole in dorsal view, not including presclerites.
PTH (petiolar height): maximum height of petiole in profile view, including sternal process and dorsal node, if distinct.
PTW (petiolar width): maximum width of petiole in dorsal view.
PPL (postpetiolar length): maximum length of postpetiole in dorsal view, not including presclerites.
PPW (postpetiolar width): maximum width of postpetiole in dorsal view.
PPH (postpetiolar height): maximum height of postpetiole in profile view, including sternal process and dorsal node, if distinct.
CI (cephalic index) = HW ÷ HL × 100.
SI (scape index) = SL ÷ HW × 100.
MI (mandibular index) = MaL ÷ HW × 100.
PI (petiolar index) = PTW ÷ PTL × 100.
PPI (postpetiolar index) = PPW ÷ PPL × 100.
PPHI (postpetiolar height index) = PPH ÷ PPL × 100.
Abbreviations of the type depositories are as follows:
Holotype. Australia • 1 worker; Western Australia, Newman; 22°44'S, 119°02'E; ca 575 m a.s.l.; 8 Mar. 2023; Jane M. McRae leg.; collected via subterranean scraping; BENNSPECIMENID_746962.1;
Paratype. Australia • 1 worker; same data as for holotype; BENNSPECIMENID _746962;
Unfortunately, both the holotype and paratype specimens were brittle and partially damaged during the mounting process. A photograph of the fully intact specimens in liquid prior to mounting is shown in Fig.
Profile view of Leptanilla voldemort sp. nov. (holotype) from Western Australia. The postpetiole and gaster of the specimen, which were disconnected from the main body during mounting, were imaged separately and subsequently attached to the body digitally while ensuring consistency of scale.
Dorsal view of Leptanilla voldemort sp. nov. (holotype) from Western Australia. The postpetiole and gaster of the specimen, which were disconnected from the main body during mounting, were imaged separately and subsequently attached to the body digitally while ensuring consistency of scale.
All measurements are in millimetres (mm).
Holotype : HW 0.26; HL 0.35; SL 0.36; MaL 0.21; WL 0.59; PrW 0.16; MW 0.12; PTL 0.28; PTH 0.08; PTW 0.07; PPL 0.24; PPW 0.10; PPH 0.10; CI 73, SI 139, MI 81, PI 25, PPI 39, PPHI 42.
Paratype (n = 1): HW 0.27; HL 0.36; SL 0.35; MaL 0.20; WL 0.61; PrW 0.16; MW 0.12; CI 75, SI 128, MI 75.
Head. Head longer than wide (CI = 73–75). In full-face view (Fig.
Mesosoma. In dorsal view, maximum width of pronotum (PrW = 0.16 mm) wider than posterior portions of mesosoma (Fig.
Metasoma. Metasoma elongated in both dorsal and lateral view (PL + PPL ≈ WL). In dorsal view (Fig.
Sculpture. Sculpture absent. Most of the body slick and shiny (i.e. not a result of glare from diffusing light when imaging).
Pubescence. Pubescence present on most of the body, especially antennae and legs, but sparse to absent on propodeum and metasoma. Numerous suberect to erect setae on dorsal and ventral surfaces of pronotum, cranium, and mandibles. Long basal and subapical setae on mandibles.
Colouration. Pale gold to amber. Colouration slightly lighter at extremities.
Castes. Male and gyne unknown.
The species epithet pays tribute to the antagonist in the Harry Potter book series, Lord Voldemort, a terrifying wizard who, like the new ant, is slender, pale, and thrives in darkness. The species epithet is a noun, and thus invariant.
Only known from the type locality within the Pilbara region of Western Australia.
Leptanilla voldemort sp. nov. was collected from a hot grassland in the north-west Pilbara, a region characterised by very hot summers (average maximum 36–39 °C), low winter minima (average minimum 6–12 °C), low average annual rainfall (200–350 mm), and high evaporation (average annual potential evaporation 3200–4000 mm) (
The worker of L. voldemort sp. nov. is easily distinguished from the other native Australian leptanilline species, L. swani Wheeler, 1932, which is evidently sympatric with L. voldemort sp. nov. (see new collection data below). First, L. voldemort sp. nov. has distinctly elongated mandibles (MI = 75–81) and antennae (SI = 128–139), while in L. swani these appendages are stouter and shorter (MI = 44–56, SI = 59–74). Second, L. voldemort sp. nov. possesses metasomal segments that are two to four times longer than wide (PI = 25, PPI = 39), while in L. swani these segments are almost as long as wide (PI = 56–70, PPI = 83–100). Finally, L. voldemort sp. nov. (WL = 0.59–0.61 mm) is larger in size than L. swani (WL = 0.35–0.45 mm). In general, the gracile phenotype of L. voldemort sp. nov. is distinctive among the genus Leptanilla, except for Leptanilla laventa Griebenow, Moradmand & Isaia, 2022, a species described from Iran. Specifically, the elongated antennae and petiole of workers in both L. voldemort sp. nov. (SI = 128–139, PI = 25) and L. laventa (SI = 160–163, PI = 29–32) are not observed in other Leptanilla species (SI<100, PI>31) (
Below we provide measurements for three worker specimens of L. swani. Collection data for the first two specimens are as follows: Australia; 2 workers; Western Australia, Newman; 22°47'S, 119°9'E; ca 537 m a.s.l.; 9 May 2022; Jane M. McRae leg.; collected via subterranean scraping; BENNSPECIMENID_735794 and BENNSPECIMENID_735840;
BENNSPECIMENID_735794 (Fig.
BENNSPECIMENID_735840: HW 0.22; HL 0.31; SL 0.16; MaL 0.12; WL 0.45; PrW 0.15; MW 0.12; PTL 0.15; PTH 0.11; PTW 0.09; PPL 0.12; PPW 0.10; PPH 0.12; CI 71, SI 72, MI 55, PI 59, PPI 87, PPHI 106.
CASENT0172006: HW 0.20; HL 0.28; SL 0.12; MaL 0.09; WL 0.35; PrW 0.13; MW 0.11; PTL 0.11; PTH 0.10; PTW 0.08; PPL 0.08; PPW 0.08; PPH 0.10; CI 69, SI 59, MI 44, PI 70, PPI 100, PPHI 125.
Leptanilla swani Wheeler, 1932
Leptanilla voldemort sp. nov.
1 | Elongated mandibles (MI = 75–81), antennae (SI = 128–139), and metasoma (PI = 25, PPI = 39). Large body size (WL = 0.59–0.61) | L. voldemort sp. nov. |
− | Stout mandibles (MI = 44–56), antennae (SI = 59–74), and metasoma (PI = 56–70, PPI = 83–100). Small body size (WL = 0.35–0.45) | L. swani Wheeler |
Despite Australia being a global hotspot for ant diversity (
Although we collected individuals of both L. voldemort sp. nov. and L. swani within the same general locality (sites <15 km apart) in the Pilbara, the two sympatric species clearly exhibit contrasting morphologies. Whereas L. swani is stout and compact (Fig.
We are grateful to Stuart Halse, Melanie McGellin, and Melita Pennifold from Bennelongia Environmental Consultants for their assistance with the specimens and comments on the manuscript, and Nikolai Tatarnic from the Western Australian Museum for his assistance with deposition of the specimens. We also thank Zachary Griebenow and Francisco Hita Garcia for their comments on a previous version of the manuscript.
The authors have declared that no competing interests exist.
No ethical statement was reported.
M.K.L.W. is supported by a Forrest Fellowship from the Forrest Research Foundation.
M.K.L.W. studied, imaged and described the species, and wrote the manuscript. J.M.M. oversaw fieldwork and processing of specimens. Both authors proofread and edited all versions of the manuscript.
Mark K. L. Wong https://orcid.org/0000-0002-6248-3103
All of the data that support the findings of this study are available in the main text.