Protanilla rong, Griebenow & Richter & Economo & Dang & Yamada, 2025

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, European Journal of Taxonomy 987, pp. 98-145 : 116-121

Protanilla rong sp. nov.

urn:lsid:zoobank.org:act:548AA897-78C9-4D5E-911B-EBEBA3721404

Figs 11–13

Surface mesh of gyne: https://sketchfab.com/3d-models/casent0745747-protanilla-rong-queen-9c0c45b 9ece544bb96cba5518c8762c1

Surface mesh of worker: https://sketchfab.com/3d-models/casent0745809-protanilla-rong-worker-7349bc16ae7d4520a9f5395e29c0cd0f

Surface mesh of larva: https://sketchfab.com/3d-models/casent0745741-protanilla-rong-larva-83ab874 c2fa8426ab1f43d33872e0125

Diagnosis

Worker

Lateral cranial margins converging anteriorly; cranium not bulging towards vertex. Dorsal mandibular articulation visible in full-face view, acute. Clypeal surface planar, posteriorly not elevated above frons; posteromedian margin entire; median clypeal ridge present, visible externally; outline campaniform. Labrum armed with three peg-like chaetae. Mandible linear, without vertical dorsal lamella or laterodorsal longitudinal groove; dorsomedial margin with single row of ~12 peg-like chaetae; lateral mandibular face glabrous. Labial palp 1-merous. Meso- and metatibial spur formula 0,1p. Petiole sessile, with dorsal node having distinct posterior face; anterior face linear in profile view. In dorsal view, length and breadth of petiolar node subequal. Subpetiolar process present, projecting ventrad the remainder of ventral margin of abdominal sternite II; abdominal sternite II with margin not concave posterad subpetiolar process; fenestra present. Abdominal segments II–III without tergotergal and sternosternal fusion. Dorsal node of abdominal segment III with distinct posterior face, gently sloping. Abdominal segments III–IV not broadly conjoined. Soma concolorous, color yellowish.

Etymology

From the Vietnamese ‟rồng”, meaning “dragon”. The Vietnamese conception of a dragon is tubular and sinuous, with short legs, and often golden coloration. This habitus recalls the Leptanillinae , and particularly the deep yellow color of Protanilla rong sp. nov. The specific epithet is a noun in apposition, and therefore invariant.

Type material

Holotype

VIETNAM – Ninh Binh • worker; Cuc Phuong National Park , 350 m NW of park headquarters, 1–2 cm within macrotermitine mound; 20.253° N, 105.217° E ± 200 m; 145 ± 5 m a.s.l.; 10 Aug. 2022; A. Richter leg.; IEBR, CASENT0842870 .

Paratypes

VIETNAM – Ninh Binh • 7 workers; same data as for holotype; IEBR, CASENT0842862 , CASENT0842871 to CASENT0842874 , CASENT0842876 , CASENT0842877 • 1 gyne; same data as for holotype; IEBR, CASENT0745747 .

Other material examined

VIETNAM – Ninh Binh • 1 larva; same data as for preceding; IEBR, CASENT0745741 .

Measurements and indices

Holotype

HW = 0.36 mm; HL = 0.47 mm; SL = 0.35 mm; ML = 0.25 mm; WL = 0.66 mm; PrW = 0.27 mm; MW = 0.20 mm; PTL = 0.20 mm; PTH = 0.26 mm; PTW = 0.17 mm; PPL = 0.18 mm; PPW = 0.20 mm; PPH = 0.25; CI = 76; SI = 100; MI = 70; PI = 88; PPI = 112.

Paratype workers

HW = 0.35–0.37 mm; HL = 0.43–0.47 mm; SL = 0.34–0.37 mm; ML = 0.23–0.25 mm; WL = 0.62– 0.66 mm; PrW = 0.24–0.28 mm; MW = 0.19–0.20 mm; PTL = 0.17–0.20 mm; PTH = 0.24–0.27 mm; PTW = 0.16–0.19 mm; PPL = 0.17–0.18 mm; PPW = 0.19–0.20 mm; PPH = 0.24–0.26 mm; CI = 76–82; SI = 97–101; MI = 65–70; PI (n = 6) = 82–99 mm.

Paratype gyne

HW = 0.42 mm; HL = 0.50 mm; EL = 0.10 mm; EW = 0.10 mm; SL = 0.38 mm; ML = 0.31 mm; PrW = 0.32 mm; WL = 0.86 mm; MW = 0.29 mm; PTL = 0.19 mm; PTH = 0.33 mm; PTW = 0.22 mm; PPL = 0.20 mm; PPW = 0.24 mm; PPH = 0.32 mm; CI = 78; SI = 98; MI = 79; REL = 20; OI = 100; PI = 118; PPI = 123.

Description

Worker

As for Protanilla wallacei ( Griebenow 2024: 91–93) , but dorsal mandibular articulation acute in full-face view. Posteromedian clypeal margin entire. Anterior of labrum armed with three dentiform, peg-like chaetae. Abdominal sternite II with margin sinuate in profile view, not concave posterad subpetiolar process; subpetiolar process projecting ventrad the remainder of ventral margin of abdominal sternite II; fenestra present, elliptical, not anteroposteriorly compressed, occupying whole of subpetiolar process. Color yellowish.

Gyne

Head longer than wide (CI = 84); lateral margins moderately convex; occiput emarginate. Compound eyes located slightly behind head midline. Ocelli present. Clypeus as in worker. Labrum visible in full face view; bearing one central, dentiform, peg-like chaeta and a pair of longer, straight setae below it; more distal surface of labrum covered in long, suberect setae, with a short pair of setae centrally. Mandible shape as in workers; mesal margin of mandible with rounded denticles proximally, denticles flattening towards apex; downcurved mandibular apex with three larger denticles; mesal margin proximad mandibular apex with row of 12 dentiform, peg-like chaetae, ventrad denticles; only few long setae inserted below chaetae, longest seta on inner side of apical tooth; outer mandibular surface covered sparsely in setae. Palp formula as in worker; proximal labial palpomere very short, hidden below labrum. Anterior tentorial pit indistinct, laterad and very close to antennal torulus. Postgenal ridge complete. Antenna as in worker. Alar sclerites present, but specimen dealate. Pronotum in dorsal view approximately as long and wide as scutum, with convex sides; outline convex in lateral view. Mesoscutum a rounded trapezoid in dorsal view, slightly convex in profile view. Mesoscutellum in dorsal view <0.5× mesoscutal length, slightly convex in profile view. Mesopleural area in profile view wide, with narrow meso-metapleural suture. Propodeal width in dorsal view subequal to mesoscutal width, slightly narrowing posteriorly; outline convex in lateral view. Bulla proportionally more elongate than in worker, extending anterad propodeal spiracle. Tibial spurs as in worker. Abdominal segment II about as long as wide in dorsal view (PI = 118); petiolar node anteroposteriorly compressed, with anterior face slightly concave in profile view. Anterior outline of subpetiolar process with backwards bent in distal quarter; posterior outline slightly concave in profile view; process appearing roughly triangular overall. Abdominal segment III proportionally shorter in profile view than in worker (PPI = 123). Coloration as in worker. Vestiture of short, suberect setae present, interspersed with slightly longer erect setae.

Larva

Instar uncertain. Stenocephalous, with abdominal segment XI widest. Cranium subcircular, almost globular in full-face view, surface smooth and glabrous. Antenna set slightly behind midline of cranium, in full face view as distant from other antenna medially as to lateral margin of cranium, consisting of two flat cone-shaped sensillae in small pits. Mandibles typhlomyrmecoid; ectal surface with a few rounded cuticular processes. Maxilla with two short setae laterally; maxillary palp stout, peg-like, with conical sensillum at apex, two sensillae on ectal surface proximad apex. Galea slightly narrower and longer than palp, with two short, peg-like apical setae. Labrum indistinctly separated from cranium; labral margin with four flat, conical sensilla, and row of minute cuticular projections. Labium with comb of thick microtrichia on a rectangular, shelf-like projection distally, likely representing the glossa; labial palp flat and rounded cone, with distal sensillum. Prothorax ventrally with rows of minute cuticular proceses, such rows sparser on mesothorax and ventral metathorax. Prothoracic process absent. Hemolymph taps absent from abdominal segment IV. Abdominal segments and dorsal thoracic segments covered with dense vestiture of short erect setae; additionally, longer erect setae interspersed, sparse in most of abdominal segments, dense on thorax; many hairs on thorax with short cuticular spines; abdominal terminus covered in long, stout setae.

Distribution

Known only from the type locality. Putative specimens of this species collected across northern Vietnam at Ben En, Sa Pa, Vu Quang, and Xuan Son National Parks, but not included in this study, must be examined in more detail to confirm their conspecificity.

Ecology

Respective reproductive biologies of P. wallacei and P. rong sp. nov. differ in that P. rong is presumably monogynous, with alate gynes, whereas P. wallacei is polygynous, with ergatoid gynes. All P. rong larvae in the collected colony are identical in size and therefore in the same instar, suggesting synchronous brood production. Like Leptanilla phthirigyna sp. nov., P. rong was collected in a termite mound ( Termitidae : Macrotermitinae ), a microhabitat heretofore unobserved for the Leptanillinae , to the best of our knowledge.

Remarks

Protanilla rong sp. nov. is most similar to Protanilla wallacei , a species endemic to the Sundan region, differing by a more acute dorsal mandibular articulation; subpetiolar process projecting ventrad abdominal sternite III ( Fig. 4A ); proportional enlargement of the subpetiolar fenestra ( Fig.4 ); and yellowish coloration. The gyne of Protanilla rong most closely resembles that of Protanilla lini among Protanilla in which the gyne is known ( Hsu et al. 2017), being alate rather than the ergatoid condition observed in P. wallacei ( Billen et al. 2013; Ito et al. 2022), but is distinguished from P. lini by smaller size (WL<1.0 mm) and somewhat shorter head (CI <85). Discovery of further gyne specimens in either species may necessitate emendation of this differential diagnosis.

Protanilla rong sp. nov. and Protanilla wallacei appear similar, but phylogenomic inference supports (UFBoot = 100; BPP = 1) Protanilla rong as sharing a more recent common ancestor with Protanilla wardi Bharti & Akbar, 2012 (Kerala, India), from which it differs in planarity of the anterior face of the petiolar node and smaller size (WL<0.8 mm); and the aberrant P. jongi (Taiwan), from which its habitus differs far more conspicuously. The heterospecificity of P. jongi with relatives sampled in this study, including P. wallacei , is not in question; by extension, Protanilla rong has verity under our species concept.

Figures

Fig. 11. Protanilla rong sp. nov., holotype, worker (CASENT0842870). A. Profile view. B. Dorsal view. C. Full-face view. Scale bars: A–B = 0.2 mm; C = 0.25 mm.

Fig. 12. Protanilla rong sp. nov., paratype, gyne (CASENT0745747). A. Profile view. B. Dorsal view. Scale bars = 0.25 mm.

Fig. 13. Protanilla rong sp. nov., larva (CASENT0745741). A. Profile view (Fig. 13B outlined). B. Meso- and metathorax, ventral view. C. Head, profile view. D. Antenna. E. Head, anterior oblique view (Figs. 13B, D are outlined in white). F. Mouthparts, anterior view. Scale bars: A = 0.1 mm; B–E = 0.02 mm; F = 0.01 mm.

Fig. 4. Profile of abdominal segment II, diagrammatic. A. Protanilla wallacei Griebenow, 2024. B. Protanilla rong sp. nov. Abbreviation: fen = subpetiolar fenestra.