Polyrhachis bugnioni

A rarely collected species that appears to be a denizen of primary forest.

Identification
See the Hemioptica Species Key

Distribution
This taxon was described from Sri Lanka. It is likely endemic to this country.

Biology
From Dorow and Kohout 1995:

Polyrhachis bugnioni is known only from Sri Lanka, where it might be endemic. It is apparently an inhabitant of primary forests. The following data on their nesting habits are by courtesy of Drs Karl V. Krombein and Beth B. Norden who found a nest of P. bugnioni in the myrmecophyte Humboldtia laurifolia (Fabaceae) during their fieldwork in Sri Lanka in 1993: '...The colony did not occupy an internode, but made a nest by sealing together the edges of the pair of stipules immediately above the internode. The stipules were unusually long, 45 mm, with a maximum width of 16 mm near the base. Their acuminate apices, 7 mm long, were not sealed. The edges below the apices were sealed together with silk and debris spun by the ant larvae. A sizable mass of debris and silk, 1.5 mm thick, sealed off the top of the nest 7 mm from the tips of the stipules. Access to the nest was at the base of the stipules. The inner surface of the stipules was not coated with a sheet of silk. A few small ant larvae were still attached along the edges of the stipules where, apparently, they were being used to strengthen the seal at the time we placed the nest in alcohol. The nest population consisted of the queen, 27 workers, and a number of brood (9 in cocoons, 15 small larvae and 12 eggs). The coloration of this species is unique among the ant species nesting in Humboldtia. The white femora and tibiae are a marked contrast to the black body' (Krombein, pers. comm.).

Castes
No males of this species have been collected.

Nomenclature

 *  bugnioni. Polyrhachis (Hemioptica) bugnioni Forel, 1908a: 11, pl. 1 (w.q.) SRI LANKA. See also: Dorow & Kohout, 1995: 98.

Worker
Dorow and Kohout 1995:

Dimensions (syntypes cited first): TL c. 5.49-5.74, 4.89-5,40; HL 1.43-1.47, 1.25-1.43; HW 1.18-1.25, 1.00-1.15; CI 82-85, 80-82; SL 1.65-1.72, 1.47-1.62; SI 138-140, 138-147; PW 1.28, 1.03-1.22; MTL 1.50-1.53,1.25-1.47 (10 measured).

Mandibles with 5 teeth. Clypeus in profile straight, with the base weakly impressed; the anterior margin arcuate, entire. Frontal carinae only moderately raised; area between them gently excavated anteriorly, weakly convex posteriorly; frontal furrow only marked anteriorly. Antennal scapes distinctly bent at their bases. Eyes entire, moderately large, rather flat; in full face view the eyes at most only marginally exceed the cephalic outline. Ocelli lacking. Sides of head with distinct longitudinal carina, which separates gena from ventral parts of head. Pronatal humeri obtusely angulated; dorsum gently arched, extended posteriorly, shielding greater part of the mesonotal dorsum. Metanotal groove deep, reaching on each side the metathoracic spiracles. Propodeal dorsum arched, anterior angles bluntly angulated; anterior margin gently sinuate, produced forward and partly overhanging the metanotal furrow; dorsum separated from declivity by a distinct, arch-shaped, transverse carina which extends on each side to the propodeal spiracles; declivity shorter than dorsum, concave. Petiole transverse; dorsal edge somewhat emarginated medially; lateral angles terminating in short, distinct denticles. First gastral tergite concave basally.

Mandibles very finely shagreened, with numerous piliferous pits. Anterior clypeal margin with few, moderately large, shallow, setae-bearing pits. Head, mesosoma and gaster rather closely shagreened.

Mandibles with short, semierect hairs. Anterior clypeal margin medially with a few forward directed setae. Head, mesosoma and gaster covered with moderately long, silvery adpressed pubescence, which tends to be somewhat diluted on pronatal dorsum and anterior and posterior faces of petiole. Relatively long erect hairs rather abundant over the whole of the body.

Generally black, with antennae very dark brown, save for their distal ends which are a shade lighter. Legs in syntypes and queen (Maschwitz coll.) very dark brown to black, with tibiae, except their proximal ends, mostly yellowish to reddish brown. In the recently collected specimens, the legs of the workers and a queen (Krombein & Norden coll.) are generally very light, yellow, with trochanters, proximal half of femora, proximal ends of tibiae and tarsi dark brown or black. The femora and tibiae were described as white, when the ants were collected (see below), but apparently darkened after the ants died.

Queen
Dorow and Kohout 1995:

Dimensions: TL c. 6.55-7.06; HL 1.56-1.62; HW 1.25-1.31; CI 80-81; SL 1.68-1.85; SI 134-141; PW 1.43-1.53; MTL 1.53-1.75 (2 measured).

Two dealate queens available for examination closely resemble the workers and differ only by possessing the characters identifying full sexuality, including three ocelli, complete thoracic structure and wings.

Type Material
Dorow and Kohout 1995: Syntype workers, female. Type locality: Sri Lanka (as Ceylan), Puwakpitiya (Bugnion), MHNG