Leptanilla belantan, Griebenow, 2024

Griebenow, Zachary, 2024, Systematic revision of the ant subfamily Leptanillinae (Hymenoptera, Formicidae), ZooKeys 1189, pp. 83-184 : 83

Leptanilla belantan sp. nov.

Figs 6A-C , 7 , 8A-C

Type material.

Holotype. Malaysia - Selangor • 1 worker; Genting Highlands, below Sri Layan; 1.iv.1981; W. L. Brown leg.; hill forest, red-rotten wood; MCZ:Ent:00728278. MCZC Paratypes. Malaysia - Selangor • 1 gyne; same data as for holotype; MCZ:Ent:00728275; MCZC • 3 worker, same data as for holotype; MCZ:Ent:00728276, MCZ:Ent:00728277, MCZ:Ent:00793731; MCZC • 2 worker, same data as for holotype; MCZ:Ent:00793729, MCZ:Ent:00793730; UCDC.

Measurements (mm) and indices, worker.

Holotype: HW = 0.34; HL = 0.44; SL = 0.28; LF2 = 0.05; ML = 0.2; WL = 0.56; PrW = 0.22; MW = 0.148; PTL = 0.14; PTH = 0.13; PTW = 0.08; PPL = 0.11; PPW = 0.10; PPH = 0.16; TW4 = 0.29; CI = 77; SI = 82.38; MI = 58; PI = 59; PPI = 91; TI1 = 33. Paratypes (n = 5): HW = 0.33-0.35; HL = 0.42-0.45; SL = 0.24-0.28; ML = 0.18-0.21; WL = 0.54-0.57; PrW = 0.224 -0.23; MW = 0.15-0.16; PTL = 0.14-0.16; PTH = 0.11-0.13; PTW = 0.08-0.09; PPL = 0.10-0.11; PPW = 0.09-0.10; PPH = 0.15-0.16; TW4 = 0.29-0.31; CI = 75-77; SI = 74-82; MI = 52-60; PI = 55-59; PPI = 89-98; TI1 = 32-35

Measurements (mm) and indices, gyne.

HW = 0.47; HL = 0.56; SL = 0.29; LF2 = 0.06; ML = 0.20; PrW = 0.30; MW = 0.31; PTL = 0.30; PTH = 0.21; PTW = 0.22; CI = 84; SI = 61; MI = 43; PI = 72

Worker.

Lateral margins of cranium slightly convex. Occipital carina distinct. Frontoclypeal process present, delimited from cranium by lateral carinae, with posteromedian delimitation from cranium, projecting well anterior of labrum in full-face view; apex robust, broad in outline, emarginate, bordered by laminae. Mandible short relative to head. Four teeth present on mandible; two teeth proximad apical tooth acute, subequal in size, with two denticles interposed; most proximal tooth large, distally recurved, blunt, enlarged apically (Fig. 7 ). Large, tapering basal seta absent from mandible; subapical tapering seta present (Fig. 7 ). Maxillary palp 2-merous. Scape short, not reaching cranial vertex at rest, somewhat expanded towards apex. Pedicel length subequal to that of basal flagellomere. Flagellum submoniliform; antennomere 3 subequal in length to distal antennomeres; apical flagellomere 2 × longer than subapical flagellomere. In dorsal view, pronotal margins strongly convex, pronotal width distinctly greater than mesonotal width. Pronotal dorsum moderately convex, slightly elevated above dorsal mesonotal vertex. Lateral margins of mesonotum and metapectal-propodeal complex subparallel in dorsal view; mesonotum not constricted anteriorly. Meso-metapleural suture entirely absent; fusion of mesonotum with propodeum marked by shallow excavation. Propodeum angular in profile view; propodeal declivity slanted; posterolateral corners rounded. Tarsomeres longer than broad. Meso- and metatibial spur formula 2b,2(1s,1p). Anterior margin of petiole linear in dorsal view. Abdominal segment II longer than wide, with distinct dorsal node; margins parallel in dorsal view; margin of abdominal sternite II linear in profile view, angled ventrally anteriorly; subpetiolar process present, not lamellate, anterior face concave in profile view. Length of abdominal segment II distinctly greater than that of III. Abdominal segment III longer than wide in dorsal view. Breadth of abdominal segment III less than half the breadth of abdominal segment IV in dorsal view (TI1 = 30-33). Anteroposterior length of abdominal tergite IV greater than that of V-VIII combined. Respective anteroposterior lengths of abdominal segments V-VII subequal. Coloration brown.

Gyne.

As for genus. Mandible with distinct basal and masticatory margins, edentate, not demarcated by a distinct subapical incisor; masticatory margin longer than basal margin. In dorsal view, breadth of mesonotum less than that of pronotum or metanotal-propodeal complex. Petiole longer than broad in dorsal view (PI = 0.719), constricted anteriorly along both transverse and dorsoventral axes; subpetiolar process absent. Dorsal node situated towards posterior of petiole. Abdominal segment III axial relative to posterad abdominal segments. Postsclerites of abdominal segments III-VII subequal in length. Vestiture consisting of short subdecumbent to suberect setae, longer and more abundant on gaster than on remainder of soma.

Etymology.

“Belantan” is Malay for a club-like weapon, in reference to the shape of the proximal tooth of the worker mandible, the apical expansion of which is unique in mandibular teeth observed in Leptanilla . The specific epithet is a noun in apposition and therefore invariant.

Remarks.

The worker of Leptanilla belantan is closest to that of Leptanilla judaica Kugler, 1987 and Leptanilla ujjalai Saroj, Mandi & Dubey, 2022 in appearance. Like L. ujjalai , L. belantan possesses an enlarged, truncate proximal tooth on the mandible, which in the latter species is bent distally; L. belantan differs from L. ujjalai in not having a serrated subpetiolar process and in the apex of the frontoclypeal process being emarginate, rather than entire. Castaneous coloration and lack of a meso-metapleural furrow set L. belantan apart from L. judaica . The gyne habitus of L. belantan is nearest to Leptanilla escheri (Kutter, 1948), differing in the elongation of the masticatory margin and the complete absence of ommatidia.

It is quite possible that the specimens identified as L. escheri and mentioned by Hölldobler et al. (1989) in fact belong to this species, since these also originated in peninsular Malaysia, although this speculation is unprovable because the repository of those specimens was not reported. It is also possible but unconfirmable that the undescribed Leptanilla species portrayed in Bolton (1990b: figs 8-11) corresponds to L. belantan . As with L. escheri , the placement of L. belantan in the Leptanilla thai species group must be regarded with some caution until this hypothesis can be tested with phylogenomic inference. It is conceivable that L. belantan instead belongs to the Leptanilla havilandi species group, since the worker caste of the two clades are at times distinguishable only by phenetic minutiae such as sculpturation. Unlike its putative close relatives within the Leptanilla thai species group, L. belantan exists in parapatry with the Leptanilla havilandi species group, allowing for the possibility that this species belongs to the latter clade.

The mandible of the gyne of L. belantan differs from the falcate facies observed in all other Leptanilla gynes, with the masticatory margin being longer than the basal margin. The gyne mandible in L. belantan therefore converges with the synapomorphic condition of the Poneroformicines ( Richter et al. 2022).

Figures

Figure 6. Leptanilla belantan, holotype (MCZ: Ent: 00728278), worker A profile view B dorsal view C full-face view. Scale bars: 0.2 mm.

Figure 7. Mandible of Leptanilla belantan (MCZ: Ent: 00728277), dorsal view, worker. Abbreviations: sub = subapical mandibular seta; bth = most proximal tooth. Scale bar: 0.1 mm.

Figure 8. Gyne of Leptanilla belantan (MCZ: Ent: 00728275) A profile view B dorsal view C full-face view. Scale bars: 0.5 mm (A, B); 0.2 mm (C).