Leptanilla phthirigyna, Griebenow & Richter & Economo & Dang & Yamada, 2025

Leptanilla phthirigyna sp. nov.

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Figs 19–20 View Fig View Fig

Diagnosis

Worker

Mandible with three teeth, short relative to head. Scape short relative to head. Flagellum submoniliform. Clypeal process absent; clypeal margin linear, entire. Length of subapical tapering seta ~ ½ ML. PrW ≈ MW. Pronotal and mesonotal heights of dorsa subequal. Meso-metapleural suture absent from dorsum. Anterior margin of abdominal segment II linear in dorsal view. Subpetiolar process present, not lamellate. PTL ≈ PPL.Abdominal sternites II–III projecting comparably ventrad craniocaudal axis. PPW ~ ½ TW4. Length of abdominal postsclerites IV less than combined length of abdominal postsclerites V–VIII.

Gyne

Mandible falcate, without distinct basal and masticatory margins, subapical tooth present; strongly bowed inward.Anterior clypeal margin slightly convex, without median elevation. Compound eyes absent. Meso-metapleural suture absent. Abdominal segment II as broad as long, with distinct dorsal node; subpetiolar process absent; quadrate, not constricted anteriorly along anteroposterior or lateromedian axes.

Etymology

From the Greek ‘ phthirus ʼ, meaning ‘louseʼ, and ‘ gyna ʼ, that is, ‘gyneʼ. This refers to the minute size and dorsoventral compression of the gyne, which along with elongate vestiture on the metasoma grants an ectoparasitic gestalt. Gender of specific epithet is feminine.

Type material

Holotype

VIETNAM – Ninh Binh • worker; Cuc Phuong National Park ; 20.3496° N, 105.5957° E; 400 m a.s.l.; 8 Aug. 2022; M.G. Branstetter leg.; #4349; in macrotermitine mound; IEBR, CSUENT6000054 .

GoogleMaps

Paratypes

VIETNAM – Ninh Binh • 1 gyne; same data as for holotype; IEBR, CASENT0842890 • 2 workers; same data as for holotype; IEBR, CASENT0842891 , CASENT0842892 GoogleMaps .

GoogleMaps

Other material examined

VIETNAM – Ninh Binh • 1 gyne; same data as for holotype; IEBR, CASENT0842889 GoogleMaps .

Measurements and indices

Holotype

HW = 0.20 mm; HL = 0.26 mm; SL = 0.13 mm; ML = 0.11 mm; WL = 0.33 mm; PrW = 0.13 mm; MW = 0.11 mm; PTL = 0.08 mm; PTH = 0.09 mm; PTW = 0.07 mm; PPL = 0.07 mm; PPW = 0.09 mm; PPH = 0.10 mm; TW4 = 0.20 mm; CI = 76; SI = 63; MI = 53; PI = 88; PPI = 125; TI1 = 43.

Paratype workers

HW = 0.21–0.22 mm; HL = 0.26–0.27 mm; SL = 0.13 mm; ML = 0.10–0.11 mm; WL = 0.34–0.35 mm; PrW = 0.13–0.14 mm; MW = 0.12 mm; PTL = 0.09 mm; PTH = 0.09–0.10 mm; PTW = 0.08–0.09 mm; PPL = 0.08 mm; PPW = 0.09–0.10 mm; PPH = 0.11–0.12 mm; TW4 = 0.20–0.21 mm; CI = 78–81; SI = 60–61; MI = 47–52; PI = 85–99; PPI = 113–123; TI1 = 46–48.

Paratype gyne

HW = 0.28 mm; HL = 0.34 mm; SL = 0.15 mm; WL = 0.59 mm; PrW = 0.20 mm; MW = 0.22 mm; PTL = 0.14 mm; PTH = 0.14 mm; PTW = 0.14 mm; CI = 81; SI = 53; PI = 104.

Description

Worker

Lateral margins of cranium subparallel. Occipital carina only distinct ventrally. Clypeal process absent; clypeal margin linear, entire. Mandibles short relative to head (MI = 47–53); three teeth present. Large, tapering basal seta absent from mandible; subapical tapering seta present, no longer than adjacent setae. Maxillary palp 1-merous. Scape short, less than ½ length of cranium (SI = 60–61), somewhat expanded towards apex. Pedicel length distinctly greater than that of basal flagellomere. Flagellum submoniliform; length of antennomere 3 subequal to respective lengths of antennomeres 4–6, with lengths of antennomeres 7–11 greater than those of antennomeres 4–6; antennomere 12 (i.e., apical flagellomere) 2× as long as antennomere 11. In dorsal view, pronotal margins moderately convex, pronotal width only slightly greater than mesonotal width. Pronotal dorsum planar, not elevated above dorsal mesonotal vertex. Lateral margins of mesonotum and metapectal-propodeal complex subparallel in dorsal view; mesonotum not constricted anteriorly. Meso-metapleural suture absent dorsally; present as signum in profile view. Bulla not extending anterad propodeal spiracle. Propodeum convex in profile view; propodeal declivity indistinct from dorsum; posterolateral corners of propodeum rounded. Tarsomeres longer than broad. Meso- and metatibial spur formula 1b,2b. Anterior margin of abdominal segment II linear in dorsal view. Length of abdominal segment II greater than breadth in dorsal view, distinct dorsal node present; margins parallel in dorsal view; subpetiolar process present, not lamellate, anterior face not concave in profile view. Length of abdominal segment II (PTL = 0.08–0.09 mm) subequal to that of abdominal segment III (PPL = 0.08 mm); abdominal sternite III not projecting ventrad abdominal sternite II. Length and breadth of abdominal segment III subequal in dorsal view. Breadth of abdominal segment III approximately half that of abdominal segment IV in dorsal view (TI1 = 43–48). Abdominal tergites IV–VII visible in posterodorsal view. Anteroposterior length of abdominal tergite IV twice anteroposterior length of abdominal tergite V in dorsal view. Abdominal tergite IV not constricted anteriorly. Anteroposterior lengths of abdominal tergites V–VI subequal; anteroposterior length of abdominal tergite VII much less than that of abdominal tergite VI. Sculpture largely absent. Vestiture consisting of short subdecumbent setae, longer and more abundant on gaster than on remainder of soma. Coloration yellowish.

Gyne

Labrum deeply emarginate. Cranium in full-face view rectangular; occipital margin emarginate. Clypeal process absent. Mesonotum not laterally delimited from mesopleuron by furrow. In dorsal view, breadth of mesonotum greater than that of pronotum or metanotal-propodeal complex. Propodeum without distinct declivity. Abdominal segment II subsessile, abdominal postsclerites II not constricted anteriorly, dorsal apex of petiolar node exceeding dorsal apex of abdominal tergite III; dorsal node situated towards anterior of abdominal segment II. In dorsal view, abdominal segment III conspicuously narrower than abdominal segment IV, supra-axial relative to posterad abdominal segments; lengths of abdominal postsclerites IV and VII subequal, greater than abdominal postsclerites III and V–VI. Vestiture dense, with setae coarse and suberect to subdecumbent on head and mesosoma; setae long, fine, and subdecumbent on metasoma.

Distribution

Known only from the type locality.

Ecology

Like Protanilla rong sp. nov., L. phthirigyna sp. nov. was collected just below the surface of a termite mound, a microhabitat not previously reported for the Leptanillinae . The discovery of a physogastric gyne (CASENT0842889) confirms phasic brood production in L. phthirigyna , as in all other Leptanilla for which biology is known. The existence of two gynes in a single putative colony is exceptional for Leptanilla but most be considered only circumstantial without further study: the reproductive phases of these two individuals were not synchronized, contrary to the behavior of gynes in confirmed polygynous ants that practice phasic brood production (e.g., the Cerapachys sulcinodis species-complex [ Dorylinae ]; Mizuno et al. 2021).

Remarks

The worker of Leptanilla phthirigyna sp. nov. most closely resembles that of Leptanilla okinawensis Terayama, 2013 , differing in the proportions of the pedicel, and in that the subpetiolar process is situated midway along the anteroposterior length of abdominal segment II, rather than posterad that point. The condition of the lateral meso-metapleural suture in L. okinawensis is unknown, and this species has not yet been sequenced.

Leptanilla phthirigyna sp. nov. is found by phylogenomic inference to belong to the Leptanilla revelierii species-group, corroborated by the absence of a clypeal process and the proportions of abdominal segments IV–VIII. The species belongs to an east Asian radiation of the Leptanilla revelierii species-group that also includes Leptanilla taiwanensis Ogata et al., 1995 ( Fig. 2 View Fig ).