Two New Species of Stenamma ( Hymenoptera : Formicidae ) from Indian Himalaya With a Revised Key to the Palaearctic and Oriental Species

Two new species of genus Stenamma viz Stenamma wilsoni sp. nov. and Stenamma jhitingriense sp. nov. are described from Indian Himalaya. This adds two more species to the genus from Indian Himalaya, with only Stenamma kashmirense Baroni Urbani, 1977 described earlier. A revised key to 26 species from Palaearctic and Oriental is provided here with.


INTRODUCTION
Genus Stenamma Westwood 1839 is widely distributed with 47 extant species (Bolton 2011;Liu & Xu 2011).Recently Liu & Xu (2011) described three new species of this genus and provided a revised key for the known species of Palaearctic and Oriental regions.Based on molecular evidence Branstetter (2009) redefined Stenamma as monophyletic genus.Earlier DuBois (1998) had revised the Palaearctic and Oriental species of this genus.However, the representation of this genus has been poor from Indian Himalaya, as only one species, Stenamma kashmirense, has been reported by Baroni Urbani (1977).During the course of present study two new species have been recorded and these differ considerably from already described species of this genus.A revised key (modified after Liu & Xu 2011) which includes 26 known species from Palaearctic and Oriental regions has been provided.

MATERIALS AND METHODS
The specimens were collected by the handpicking method.Digital color images were prepared by Michael Branstetter (California Academy of Sci-Department of Zoology and Environmental Sciences, Punjabi University, Patiala-147002, India e-mail: himenderbharti@gmail.com; irfangulhhh@gmail.com;yashraina007@gmail.comences) vide specimen number CASENT 0126224 (Stenamma wilsoni sp.nov.) and CASENT 0126222 (Stenamma jhitingriense sp.nov.).Taxonomic analysis was conducted using a Nikon SMZ 1500 stereo zoom microscope.Morphological terminology for measurements and indices (given in millimeters) includes: HL-Head length: The length of the head capsule excluding the mandibles, measured in full face view in a straight line from the midpoint of the anterior clypeal margin to the mid-point of the occipital margin.
HW-Head width: The maximum width of the head in full face view, excluding the eyes.
SL-Scape length: The maximum straight line length of the scape, excluding the basal constriction or neck that occurs just distal of the condylar bulb.
PW-Pronotal width: The maximum width of the pronotum in dorsal view.
ML-Mesosomal length: The diagonal length of the mesosoma in lateral view from the point at which the pronotum meets the cervical shield to the posterior basal angle of the metapleuron.
ED-Eye diameter: The maximum diameter of the eye.PL-Petiole length: Maximum length of petiole, measured from the juncture with propodeum to the juncture with postpetiole.
PH-Petiole height: The perpendicularly maximum height of the petiole, measured from the apex of the node to venter of petiole.
DPW-Dorsal petiole width: Maximum width of petiole, measured across node in dorsal view.
PPL-Postpetiole length: Maximum length of postpetiole, measured from the juncture with petiole to the juncture with gaster.
PPH-Postpetiole height: The perpendicularly maximum height of the postpetiole, measured from the apex of the postpetiolar node to the venter of postpetiole.
PPW-Postpetiole width: Maximum width of postpetiole, measured across the postpetiolar node in dorsal view.
GL: Gaster length: Length of the gaster in lateral view from the anteriormost point of first gastral segment to the posterior-most point.
TL-Total length: HL+ML+PL+PPL+GL.CI-Cephalic index: HW×100/HL.Head: Head distinctly rectangular, longer than broad in full face view; occipital margin straight; occipital corners less distinct, moderately round; lateral sides almost parallel; anterior clypeal margin convex, slightly concave in the middle; eyes small, with 5 facets in their greatest diameters, located below the mid points of the lateral sides of head; mandibles triangular, the masticatory border with 3 prominent apical teeth, and 5 less distinct basal teeth; antennae short, 12-segmented, scape stout, falling short by about 1/6 of its length to reach the occipital corners, club 4-segemented.
Mesosoma, Petiole and Postpetiole: In profile view promesonotum high and convex nearly arched, promesonotal suture less distinct; mesometanotum suture well marked making a wide groove; propodeum distinctly lower than promesonotum, convex from side to side, forms a gentle slope towards apex; propodeal spines short, as long as 1/3 the range of their bases; propodeal plates broad, as long as is the length of propodeal spines, posterodorsal corner bluntly angled, posteroventral corner rounded; petiole long, petiolar node approximately as long as anterior peduncle, anteroventral face slightly convex, posterioventral face slightly depressed, anteroventral corner of petiole bluntly angled; postpetiolar dorsum round, ventral face weakly concave, anteroventral corner slightly extruding, tooth like.
Gaster: Gaster ovate, smooth and shining all over.Sculpture: Head retirugose, except longitudinal irregular rugae below eyes and rugae in between the frontal carinae which run to the occiput; mandibles with less distinct striations; clypeus smooth; promesonotal dorsum rugose, rugae sparse, the central rugae longitudinal, sides of pronotum with indistinct rugae; propodeum and sides of mesonotum retirugose; propodeal declivity smooth; dorsum of petiolar peduncle smooth without longitudinal carina; petiole and postpetiole interweaved with fine, less distinct longitudinal rugae; gaster smooth and shining except a few short rugae at base.Pilosity: Body clothed with suberect to erect hairs, more abundant on head and gaster; on mesosomal surface hairs erect, sparse and scattered; shorter subdecumbent hairs on antennae and legs; decumbent pubescence on antennae and legs, more dense on antennal funiculus.
Distribution and Habitat: The species has been collected from a single locality of North-West region of Indian Himalaya.The specimen has been collected by hand picking, from a rotten log of wood, in open woodland on a hill slope.
Etymology: The species is named in the honour of Prof. E. O. Wilson.

Remarks:
The species is significantly different from already described species of this genus.The species has a very distinct sculpture of head and mesosoma, differs in shape and size of propodeal plates, in propodeal spines and petiole.Due to petiolar node as long as its anterior peduncle and scape not reaching to the occipital corners, this species can be easily separated from Stenamma kashmirense Baroni Urbani, 1977 (the only species reported from Indian Himalaya hitherto).However Stenamma wilsoni sp.nov. is somewhat allied to Stenamma jeriorum DuBois, 1998 and Stenamma lippulum Nylander, 1849, but can be easily separated from former by parallel sides of head and propodeal spines as long as are the propodeal plates, where as lateral sides of head are strongly convex in Stenamma jeriorum and propodeal spines shorter than propodeal plates.From Stenamma lippulum this new species is considerably distinct on the basis of the sculpture of head, where the rugae make concentric loop like structures above eyes, whereas in this new species sculpture of head is retirugose.

Stenamma jhitingriense sp. nov. (Figs 4-6)
Holotype worker: India, Himachal Pradesh, Jhitingri, 32.006475N, 76.839237E, 1750m above msl, 27 Head: Head rectangular, longer than broad in full face view; occipital margin straight; occipital corners less distinct, more round; lateral sides almost parallel; anterior clypeal margin convex, emarginate in the middle; eyes small, with 4 less distinct facets in their greatest diameters, located below the mid points of the lateral sides of head; mandibles triangular, the masticatory border with 3 prominent apical teeth, and 5 less distinct basal teeth; antennae short, 12-segmented, scape stout, falling short by nearly 1/6 of its length to reach the occipital corners, club 4-segmented.
Mesosoma, Petiole and Postpetiole: In profile view promesonotum high and convex nearly arched, promesonotal suture less distinct; mesometanotum suture well marked making a deep and wide groove; propodeum distinctly lower than promesonotum, dorsum more flat, forms a gentle slope towards apex; propodeal spines short, acute, as long as 2/5 the range of their bases; propodeal plates broad, roughly rectangular, slightly shorter than propodeal spines, bluntly angled on posterodorsal and posteroventral corners; petiole long, petiolar node approximately as long as anterior peduncle, anteroventral face straight, posteroventral face slightly concave, anteroventral corner of petiole bluntly angled; postpetiolar dorsum round, ventral face weakly concave, anteroventral corner strongly extruding.
Gaster: Gaster ovate, smooth and shining all over.Sculpture: Head retirugose, except longitudinal irregular rugae in between the frontal carinae; mandibles indistinctly striate; clypeus smooth; promesonotal dorsum with distinct retirugose sculpture, sides of pronotum with indistinct rugae; propodeum and sides of mesonotum retirugose; propodeal declivity smooth; dorsum of petiolar peduncle with a fine longitudinal central carina; petiole and postpetiole interweaved with fine, less distinct longitudinal rugae; gaster smooth and shining except a few short rugae at base.
Pilosity: Body clothed with sub-erect to erect hairs, more abundant on the head and gaster; on mesosomal surface hairs erect, sparse and scattered; shorter subdecumbent hairs on antennae and legs; decumbent pubescence on antennae and legs, more dense on antennal funiculus.
Distribution and Habitat: The specimen has been collected from a forest area of Jhitingri, Himachal Pradesh in North-West Himalayas.The specimen has been collected from leaf litter by handpicking.
Etymology: The species is named after the type locality, Jhitingri.
Remarks: Stenamma jhitingriense sp.nov. is significantly different from previously reported species of this genus due to the following combination of characters: blunt anteroventral corner of petiole, scape not reaching occipital corners, equal length of petiole and peduncle, longer propodeal spines than propodeal plates and blackish brown color of body.