Polyrhachis stitzi

Nothing is known about the biology of .

Identification
A member of the Polyrhachis continua species group in the subgenus Myrma

Kohout (2013) – Polyrhachis stitzi stands relatively close to Polyrhachis conops and I previously considered them conspecific (Kohout 1998: 519). However, after subsequent examination and direct comparison, I now believe they represent separate biological species. Polyrhachis conops is distinctly more slender with the leading edge of the antennae featuring numerous short hairs that are completely lacking in P. stitzi.

Distribution based on Regional Taxon Lists
Indo-Australian Region: New Guinea.

Castes
Male and immature stages unknown.

Nomenclature

 * bismarckensis. Polyrhachis (Myrma) conops var. bismarckensis Karavaiev, 1927e: 46 (w.) NEW GUINEA (Bismarck Archipelago). [Junior primary homonym of bismarckensis Forel, above.] Replacement name: stitzi Santschi, 1928h: 139.
 *  stitzi. Polyrhachis (Myrma) conops var. stitzi Santschi, 1928h: 139. Kohout, 2013: 26 (q.). Replacement name for bismarckensis Karavaiev, 1927e: 46. [Junior primary homonym of bismarckensis Forel, 1901b: 33.] Junior synonym of conops: Kohout, 1998: 519. Revived from synonymy and raised to species: Kohout, 2013: 25.

Worker
Kohout (2013) - Dimensions: TL c. 9.63-10.63; HL 2.62-2.74; HW 2.03-2.15; CI 77-78; SL 3.43-3.53; SI 164-169; PW 1.91-2.02; MTL 3.58-3.78 (2 measured).

Anterior clypeal margin arcuate, narrowly medially truncate. Clypeus with blunt, rather indistinct median carina, virtually straight in profile with shallow depression anteriorly and weakly impressed basal margin. Frontal triangle distinct. Frontal carinae sinuate with margins only moderately raised; central area flat with poorly indicated frontal furrow. Sides of head in front of eyes straight, weakly converging towards mandibular bases; behind eyes sides produced into blunt carina extending towards rather prominent occipital corners. Eyes convex, distinctly protracted posteriorly; in full face view clearly exceeding lateral cephalic outline. Ocelli lacking. Pronotal dorsum wider than long with relatively short, broad-based, acute spines that are anterolaterally directed, somewhat dorsomedially flattened and curve slightly downwards; lateral edges of spines acute and continuous with weakly upturned margins of pronotum. Promesonotal suture distinctly impressed laterally, rather flat medially; mesonotal dorsum transverse with only weakly raised lateral margins, converging into medially flat, metanotal groove. Propodeal dorsum with lateral margins raised anteriorly, virtually flat posteriorly and terminating in distinct, minute teeth with inner borders continuous medially for short distance and terminating in blunt, rather indistinct, transverse carina that somewhat divides dorsum from declivity. Petiole scale-like, dorsal margin armed with two broad-based, tooth-like spines with inner margins forming widely open, ‘U’-shaped dorsum of segment with indication of rudimentary intercalary tooth; lateral margin of petiole below base of each spine with distinct, acute tooth. Anterior face of first gastral segment flat, with anterodorsal margin rather narrowly rounding onto dorsum.

Mandibles distinctly, longitudinally striate. Clypeus reticulate-punctate with rest of head and mesosoma, including sides, distinctly, rather regularly, longitudinally striate; propodeal declivity and petiole, including spines, finely reticulate-punctate. Gaster shagreened.

Mandibular masticatory borders and outer margins with numerous semierect, golden hairs. Anterior clypeal margin medially with several medium length, anteriorly directed, golden setae and fringe of shorter setae laterally. Numerous short to medium length, erect to semierect hairs on clypeus, along frontal carinae and sides of head; number of hairs decreasing posteriorly with only a few shorter hairs on vertex. Antennal scapes, mesosoma, petiole and legs without hairs. Gaster with only a few, rather short, posteriorly inclined hairs, scattered towards apex and venter. Closely appressed, very short, white or greyish pubescence variously distributed over most body surfaces, including dorsum of gaster.

Colour. Black; mandibular masticatory borders lined reddish brown; antennae with funicular segments progressively lighter, yellowish brown towards apices. Legs, including mid and hind coxae, medium reddish brown; front coxae and tarsi shade darker. Gaster reddish brown.

Queen
Kohout (2013) - (not previously described). Dimensions: TL c. 11.54-11.89; HL 2.62-2.71; HW 1.95-2.09; CI 74-77; SL 3.33-3.38; SI 162-171; PW 2.37-2.40; MTL 3.48-3.53 (2 measured). Queen larger than worker with usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings. Pronotal spines distinctly shorter, broad-based. Mesoscutum only marginally wider than long; lateral margins strongly converging anteriorly into narrowly rounded anterior margin; median line distinct; parapsides virtually flat; mesoscutum in profile with relatively low, widely rounded anterior face and only slightly convex dorsum. Mesoscutellum only weakly convex, not distinctly elevated above dorsal plane of mesosoma. Propodeum convex in outline with lateral margins terminating in medially directed, short ridges and blunt border dividing propodeal dorsum from declivity. Petiole with dorsal spines distinctly shorter and wider at bases; dorsum with distinct intercalary tooth. Dorsum of mesoscutum with several short, erect hairs and a few marginally longer hairs on dorsum of mesoscutellum. Sculpturation, pubescence and colour very similar to worker.

Type Material


Kohout (2013) - The holotype of P. conops stitzi cannot be found in the Karavaiev collection or in the Stitz collection  and appears to have been lost. However, during one of my visits to the Zoological Museum of Humboldt University in Berlin, that houses the bulk of the Stitz collection, I located a small bottle containing five unidentified Polyrhachis specimens labelled ‘Ralum Dahl’. The series included 2 workers and 3 alate queens, all callows in various stages of pigmentation, with both workers and two queens in a sound condition for dry mounting. Their subsequent comparison with P. conops types, together with Karavaiev’s brief description, supports my opinion that these specimens actually represent P. conops stitzi. Considering that the holotype was also a callow specimen (‘The segments of the gaster, from third on, dark yellowish-brown’), it seems reasonable to conclude that these specimens are part of the original series from which Stitz sent a single worker specimen to Karavaiev (1927: 46), who diagnosed is as follows: ‘Polyrhachis (Myrma) conops For. var. bismarckensis nova. (worker character). Clypeus ganz wie bei subsp. simplex, ohne Ausschnitt beiderseits des geradlinig abgestutzten Vorterrandes. Augen eiförmig, vorn breiter, konvex, schief gestellt, das spitzere Hinterende etwas sackförmig nach hinten hervorragend. Petiolusschuppe wie beim Arttypus. Gastersegmente, vom dritten an, dunkel ockerfarben. Bismarckarchipel, ein (worker character), von H. Stitz. Berliner Zool. Museum, erhalten.’

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Kohout R. J. 2013. A review of the Polyrhachis continua species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae: Formicinae) with keys and descriptions of new species. Australian Entomologist 40(1): 13-46.
 * Robson Simon Database Polyrhachis -05 Sept 2014