Leptanilla sapa Griebenow & Richter & Economo & Dang & Yamada 2025, sp. nov.
Creators: name: Griebenow, Zachary Hayes
name: Richter, Adrian
name: Economo, Evan P.
name: Dang, An Van
name: Yamada, Aiki
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Leptanilla
Leptanilla sapa

description: Leptanilla sapa Yamada sp. nov.
urn:lsid:zoobank.org:act: E28E31C4-959D-43D4-BA12-24E43BF259AA
Figs 16–17, 18 Aii
Surface mesh of worker: https://sketchfab.com/3d-models/casent0745756-leptanilla-sapa-worker-ab53 16ce932d4337a96edd278ec52e23
Surface mesh of gyne: https://sketchfab.com/3d-models/casent0745762-leptanilla-sapa-queen-28da0ae 5cc904a47965eeda0cef2d1e1
Diagnosis
Worker
As for Leptanilla belantanoides sp. nov., but with the differences stipulated under Description.
Gyne
Mandible falcate, without distinct basal and masticatory margins, edentate, with two weak blunt denticles. Anterior clypeal margin slightly convex, with median elevation. Compound eye present, with four ommatidia. Meso-metapleural suture laterally present. Abdominal segment II longer than broad, without distinct dorsal node; subpetiolar process absent; rectangular, not constricted anteriorly along anteroposterior or lateromedian axes.
Etymology
From Sa Pa, the type locality of this species. The specific epithet is a noun in apposition and therefore invariant.
Type material
Holotype
VIETNAM – Lao Cai • worker; Hoang Lien National Park, Sa Pa, Mt. Phan Xi Pang, Cong Troi; 1800–1900 m a.s.l.; 8 Oct. 2006; K. Eguchi leg.; Eg08x06-12; IEBR, CASENT0745756.
Paratypes
VIETNAM – Lao Cai • 1 gyne; same data as for holotype; IEBR, CASENT0745762 • 12 workers; same data as for holotype; IEBR, CSUENT6000020 to CSUENT6000031.
Other material examined
VIETNAM – Lao Cai • 2 workers; Hoang Lien National Park, Sa Pa, Mt Phan Xi Pang, Cong Troi; 2000– 2200 m a.s.l.; 28 Apr. 2002; K. Eguchi leg.; Eg02-VN-155; IEBR, CSUENT6000032, CSUENT6000033 • 3 workers; same locality as for preceding; 28 Apr. 2002; K. Eguchi leg.; Eg02-VN-151; Katsuyuki Eguchi personal collection, CSUENT6000041 to CSUENT6000043 • 2 workers; Hoang Lien National Park, Sa Pa, Mt Phan Xi Pang; 22.35121° N, 103.77642° E; 2000 m a.s.l.; 20 Sep. 2017; K. Eguchi leg.; Eg24ix17-378; IEBR, CSUENT6000034, CSUENT6000035 • 5 workers; same locality as for preceding; 22.34609° N, 103.77459° E; 2008 m a.s.l.; 27 Sep. 2017; K. Eguchi leg.; Eg27ix17-451; IEBR, CSUENT6000036 to CSUENT6000040 • 3 workers; same locality as for preceding; 22.34600° N, 103.77469° E; 2006 m a.s.l.; 27 Sep. 2017; K. Eguchi leg.; Eg27ix17-447; Katsuyuki Eguchi personal collection, CSUENT6000044 to CSUENT6000046.
Measurements and indices
Holotype
HW = 0.36 mm; HL = 0.49 mm; SL = 0.27 mm; ML = 0.25 mm; WL = 0.61 mm; PrW = 0.24 mm; MW = 0.18 mm; PTL = 0.18; PTH = 0.13 mm; PTW = 0.11 mm; PPL = 0.13 mm; PPW = 0.11 mm; PPH = 0.17 mm; TW4 = 0.35 mm; CI = 74; SI = 74; MI = 68; PI = 59; PPI = 83; TI1 = 32.
Worker paratypes
HW = 0.37–0.39 mm; HL = 0.48–0.54 mm; SL = 0.26–0.31 mm; ML= 0.22 –0.26 mm; WL = 0.62– 0.71 mm; PrW = 0.25–0.28 mm; MW = 0.18–0.20 mm; PTL = 0.18–0.22 mm; PTH = 0.13–0.15 mm; PTW = 0.11–0.12 mm; PPL = 0.14–0.16 mm; PPW = 0.12–0.13 mm; PPH = 0.19–0.21 mm; TW4 = 0.35–0.40 mm; CI = 74–77; SI = 71–77; MI = 60–65; PI = 55–58; PPI = 76–87; TI1 = 30–35.
Paratype gyne
HW = 0.56 mm; HL = 0.65 mm; ML = 0.41 mm; WL = 1.11 mm; PrW = 0.38 mm; MW = 0.38 mm; PTL = 0.63 mm; PTH = 0.32 mm; PTW = 0.39 mm; CI = 87; SI = 65; MI = 72; PI = 61.
Description
Worker
As in Leptanilla belantanoides sp. nov., but clypeal process posteromedially not clearly delimited from cranium; apex strongly bilobed with distinctly concave anterior margin (Fig. 18 Aii). Proximal mandibular tooth about twice as long as wide, distally slightly recurved. Pronotal dorsum moderately convex, slightly elevated above dorsal mesonotal vertex. Meso-metapleural suture indistinct, faintly furrowed. Bulla reaching propodeal spiracle but not extending anterad. Propodeum rather rounded in profile view; propodeal declivity slanted; posterolateral corners rounded. Tibial spur formula 2b,2(1b,1p). Margins of abdominal segment II subparallel, slightly convex around node in dorsal view. Breadth of abdominal segment III less than half the breadth of abdominal segment IV in dorsal view (TI1 = 30–35). Mesopectus and ventral surface of petiolar sternite with reticulate sculpture. Coloration castaneous.
Gyne
Labrum deeply emarginate. Cranium in full-face view subrectangular, widest at level of midpoint of genae below eyes; occipital margin linear. Clypeal process absent. Mesonotum laterally delimited from mesopleuron by furrow. In dorsal view, breadth of mesonotum less than that of pronotum or metanotal-propodeal complex. Propodeum with distinct declivity. Abdominal segment II dorsoventrally compressed, subcylindrical, longer than wide, without distinct dorsal node; margins subparallel in dorsal view, weakly converging posteriorly; subpetiolar process absent. In dorsal view, abdominal segment III not conspicuously narrower than abdominal segment IV; axial relative to posterad abdominal segments. Abdominal postsclerites III shorter than postsclerites IV–VII; the latter subequal in length. Vestiture consists of short subdecumbent to suberect setae, longer and more abundant on gaster than on remainder of soma. Coloration pallid.
Distribution
Known only from the type locality.
Ecology
Leptanilla sapa sp. nov. is relatively common in the vicinity of Sa Pa, corresponding to Leptanilla sp. eg-1 reported by Eguchi et al. (2014: 22). The colonies were found under moss layers in a cloud forest (K. Eguchi pers. com.). One colony (Eg27ix17-447) contained a paralyzed mecistocephalid centipede (Chilopoda: Geophilomorpha) fed upon by larvae. The upper limit of the elevational range of L. sapa sp. nov. (2200 m) surpasses that reported for any other Leptanilla – only its close relative L. ujjalai and an undescribed male morphospecies of the Leptanilla revelierii species-group (Leptanilla zhg-my09) approach this, being collected at 2014 m and 1900 m, respectively (Saroj et al. 2022: 6; AntWeb 2024).
Remarks
Leptanilla sapa sp. nov. is doubtlessly a close relative of Leptanilla belantanoides sp. nov. and Leptanilla belantan, and therefore belongs to the Leptanilla thai species-group. The worker caste differs from both these species in that the apex of the truncate proximal tooth of the mandible is not at all expanded, nor is this tooth recurved distally; and in that the meso-metapleural suture is distinctly present laterally. Abdominal segment III is proportionally longer in worker L. sapa sp. nov. than in either of these species (PPI = 73–88), while abdominal segment II is also proportionally longer in L. sapa than in L. belantanoides (Fig. 18B).
While the phenotype of the worker caste differs little among L. sapa sp. nov. and its close relatives, the gyne of this species diverges conspicuously from that of L. belantan in the presence of compound eyes, with more ommatidia than ever before described in Leptanilla; falcate mandible, without distinct masticatory margin; presence of distinctly impressed meso-metapleural suture; and subrectangular abdominal segment II, lacking the anterior constriction observed in L. belantan along the dorsoventral and lateromedian axes, longer than any of the posterad abdominal segments. This striking differentiation in the gyne corroborates the allospecificity of L. sapa with L. belantan.
It remains possible that the phenotypic differences among these three allopatric species in fact represent regional variation in a single geographically widespread species. This could only be falsified by the discovery of two or more of these species in sympatry, while maintaining morphometric distinctness. For the time being, we are confident that Leptanilla sapa sp. nov., Leptanilla belantanoides sp. nov. and L. belantan represent distinct species, since the differentiation in the worker caste among these putative species is qualitatively equivalent to that observed between Leptanilla charonea and Leptanilla zaballosi Barandica et al., 1994, which occur in sympatry and are indubitably allospecific (López et al. 1994; Griebenow 2024). Description of the unknown male of L. sapa will be invaluable for assessing its distinctness from L. belantanoides.
description: Published as part of Griebenow, Zachary Hayes, Richter, Adrian, Economo, Evan P., Dang, An Van & Yamada, Aiki, 2025, Four new species of Leptanillinae (Hymenoptera: Formicidae) from northern Vietnam described with phylogenomics and micro-computed tomography, pp. 98-145 in European Journal of Taxonomy 987 on pages 129-133, DOI: 10.5852/ejt.2025.987.2867, http://zenodo.org/record/15255273