Strumigenys nepalensis

Known from a number of rainforest habitats, all recorded collection data for this species are from litter samples. In Hong Kong it is a common species in urban forest patches or disturbed grassland (e.g. Mai Po Nature Reserve), with only a few records collected within secondary forests and one record within Feng Shui woods. Elevation records ranged from 1 to 135 m, suggesting that this species might prefer lowland habitats. The association of this species with relatively disturbed habitats suggests a potential tramp species, although other biological characteristics (e.g. polygyny, unicoloniality) are unknown at present (Tang et al., 2019).

Identification
Bolton (2000) - A member of the Strumigenys rostrata-group. Recognition of nepalensis is easy as it is the only species with 4-segmented antennae currently known from the regions under discussion. Its only known close relative in these regions is Strumigenys atropos; details of their differentiation are given under the latter name. The species is widely distributed but apparently relatively uncommon.

Distribution
Records of Strumigenys nepalensis in Hong Kong expand the current known native range of this species by 800 km eastward from Vietnam. A record from Mauritius (Casent0799280, Ile Aux Aigrettes, −20.419017, 57.730183, 5 m a.s.l., A. Suarez 2.VI.2005; Doug Booher pers. comm.) confirms the tramp character of this species. Specimens collected from Hong Kong, Macau and Mauritius are considered introduced (Tang et al., 2019).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia, Singapore. Oriental Region: India, Nepal, Thailand, Vietnam. Palaearctic Region: China.

Nomenclature

 *  nepalensis. Strumigenys nepalensis De Andrade, in Baroni Urbani & De Andrade, 1994: 57, figs. 33, 34 (w.q.) NEPAL. Combination in Smithistruma: Bolton, 1995b: 385; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 124. See also: Bolton, 2000: 460.

Worker
TL, holotype 1.49, paratypes 1.44-1.49; HL holotype 0.39, paratypes 0.39-0.40; HW holotype 0.29, paratypes 0.29-0.30; eye maximum diameter holotype and paratypes 0.03; SL holotype 0.18, paratypes 0.17-0.19; ML holotype 0.09, paratypes 0.08-0.09; AL holotype 0.41, paratypes 0.39-0.42; PW holotype 0.19, paratypes 0.19-0.20; petiolar node maximum length holotype 0.10, paratypes 0.09-0.10; maximum width of the petiole holotype and paratypes 0.10; postpetiolar node maximum length holotype 0.13, paratypes 0.12-0.13; maximum width of the postpetiole holotype 0.17, paratypes 0.17-0.18; gaster maximum width holotype 0.27, paratypes 0.25-0.28. CI holotype 74, paratypes 74-77; SI holotype 62, paratypes 57-62; MI holotype 23, paratypes 20-23; SMI holotype 200, paratypes 200-237.

Head strongly converging anteriorly and with rounded occipital corners. Dorsal border of the antennal scrobes laminar. Eyes small, ventral to the antennal scrobes. Preocular lamina narrow and straight. Clypeus as broad as long. Anterior clypeal margin transverse, its median portion with a small prominence. Scapes slightly less than ½ of the head length, moderately broadened, flat and sharply bent at the base. Antennae with four antennomeres, the last joint longer than the rest of the funiculus. Labrum elongate, broad and rounded, longer than half of the masticatory margin. Mandibles short, less than 1/4 of the head length, slightly narrow and triangular; base of the masticatory border with a short diastema (partly covered by the clypeus when the mandibles are closed) and a stout and blunt tooth. True masticatory margin with a row of 5 teeth of which the third is the longest one, followed by two smaller teeth and a denticulate space before the pointed apex.

Trunk: dorsum with a faint median longitudinal carina bifurcating posteriorly on the anterior part of the propodeum. Promesonotal suture visible in dorsal view. Mesonotum in side view slightly convex. Lateral sides of mesonotum and propodeal dorsum marginate. Propodeum in profile angled at about 100°. Propodeal teeth triangular, acute and with broad infradental lamella.

Spongiform processes well developed on the pedicel, more projecting ventrally than laterally; the lateral projections connected each other by a thin dorsal lamina on the posterior articulation of the nodes. Ventral side of the petiole with a broad spongiform lamina narrower under the node. Petiolar lateral spongiform processes widening caudally. Posterolateral processes of the postpetiole reaching the gaster caudally.

Petiolar node slightly truncate anteriorly, ca. 1/3 shorter than the postpetiole. Postpetiole more than half wider than the petiole.

Gaster oval with protruding sting.

Sculpture: clypeus, cephalic dorsum, dorsum of the alitrunk and petiole reticulo-punctate. Scapes and legs simply punctate. Mandibles and dorsum of the postpetiole finely punctate and shining. Pleurae smooth and shining except some punctures on the anterior portion of the propleurae and on the dorsal border of the pleurae. Propodeal declivity smooth. Base of the first gastral tergite costulated, the remaining portion of the gaster smooth and shining.

Colour: generally brownish, slightly lighter on the trunk and appendages.

Pilosity: cephalic dorsum with short, subdecumbent, clavate hairs directed anteriorly. The same type of hairs but shorter on most of the clypeus. Rare, suberect, slightly clavate hairs twice as long than the preceding ones on posterior part of the vertex. Lateral sides of the head, external border of the scape, lateral and anterior sides of the clypeus with decumbent spatulate hairs, slightly longer than those on the dorsum of the head. Mandibles and funiculi with short, appressed, pointed hairs. Dorsum of alitrunk with 5 pairs of long, erect setae; two similar pairs on the petiole, and another two on the postpetiole; similar setae irregularly sparse over the gaster. Rare, appressed clavate hairs on the dorsum of the alitrunk and petiole. Legs covered with ticker, appressed, pointed hairs.

Queen
TL 1.71-1.74; HL 0.42; HW 0.32; eye maximum diameter 0.06; SL 0.18-0.19; ML 0.09; AL 0.47; PW 0.23-0.24; petiolar node maximum length 0.07-0.10; petiolar node maximum width 0.12; postpetiolar node maximum length 0.13-0.15; postpetiolar node maximum width 0.18-0.20; gaster maximum width 0.35-0.39. CI 76; SI 56-59; MI 21; SMI 200-211.

Except for the usual differences due to caste determination, very similar to the worker from which it differs essentially in the following characters:

Trunk: with the propodeal suture impressed. Posterior portion of mesonotal disc and scutellum flat.

Petiole truncate anteriorly and slightly concave, its node almost two times broader than long.

Pilosity: dorsum of alitrunk with 7-8 pairs of long, erect setae similar to those of the worker.

Type Material
Holotype: worker, 6 km NW of Narainghat, 250m, Nepal. Natural History Museum Basel Nepal Expedition, 1976, in the collection of the Natural History Museum, Basel, Switzerland.

Paratypes: ten workers and four dealate gynes, same data as the holotype; three workers from 5 km E of Manhari, 350m, Nepal. Natural History Museum Basel Nepal Expedition, 1976; one worker from Darugiri, 450 m, Garo Hills, (Megalaya, India), Natural History Museum Basel Megalaya Expedition, 1976. Most paratypes in the Natural History Museum, Basel; some paratypes deposited in the Natural History Museum, London.

Bolton (2000) - Holotype worker, paratype workers and queens, NEPAL: 6 km. NW of Narainghat, 30.v.1976, 250 m. (W. Wittmer & C. Baroni Urbani); paratype workers, NEPAL: 5 km. E of Manhari, 2.vi.1976 (W. Wittmer & C. Baroni Urbani), INDIA: Megalaya, Darugiri, Garo Hills, 450 m., 1976 [examined].

Etymology
nepalensis is a Latin neologism indicating the provenance from Nepal.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C., and M. L. De Andrade. 1994. First description of fossil Dacetini ants with a critical analysis of the current classification of the tribe (Amber Collection Stuttgart: Hymenoptera, Formicidae. VI: Dacetini). Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie) 198: 1-65.
 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * CSIRO Collection
 * Eguchi K.; Bui T. V.; Yamane S. 2011. Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), part I  Myrmicinae and Pseudomyrmecinae. Zootaxa 2878: 1-61.
 * Leong C. M., S. F. Shiao, and B. Guenard. 2017. Ants in the city, a preliminary checklist of Formicidae (Hymenoptera) in Macau, one of the most heavily urbanized regions of the world. Asian Myrmecology 9: e009014.
 * Liu C, B. Guénard, F Hita Garcia, S. Yamane, B. Blanchard, and E. Economo. New records of ant species from Yunnan, China. Submitted to Zookeys