Pogonomyrmex odoratus Kusnezov 1949

 

Pogonomyrmex (Ephebomyrmex) odoratus Kusnezov, 1949; 302, figs. 1, 2 (worker, queen, male). Syntypes examined: x workers not examined [FML], ARGENTINA, Río Negro Province: Bariloche, Cerro Otto (N. Kusnezov leg.) (FML worker here designated LECTOTYPE).

 

Ephebomyrmex odoratus Kusnezov; Kusnezov, 1960; 354. First combination in Ephebomyrmex.

 

Pogonomyrmex odoratus Kusnezov; Snelling & Hunt, 1976: 75, fig. 25. Revived combination in Pogonomyrmex.

 

Worker

Diagnosis.  Within the P. angustus group, the combination of: (1) dorsum of mesosoma, posterior face of petiole, and dorsum of postpetiole smooth and shining, and (2) head and mesosoma mostly concolorous amber-orange to brownish-orange, gaster dark orangish-black, and (3) angulate juncture between anterior surface of petiole and peduncle uniquely characterize this species.

Measurements - (n = 13). HL 1.00-1.25; HW 0.86-1.08; MOD 0.24-0.29; OMD 0.15-0.24; SL 0.79-0.96; PNW 0.62-0.73; HFL 0.94-1.15; ML 1.18-1.60; PW 0.20-0.30; PPW 0.39-0.45.  Indices: SI 79.63-96.00; CI 82.46-95.50; OI 24.53-27.91; HFI 91.43-110.64.

Description.  Small species (HW = 0.86-1.08 mm), head longer than wide (CI = 82.46-95.50); posterior margin flat in full-face view.  Longitudinal cephalic rugae coarse, widely spaced, slightly wavy, initiating on frontal lobes, one to few rugae rarely extend to posterior margin; usually 14-18 rugae present between eyes.  Rugae also arc from mandibular margins to frontal lobes and traverse longitudinally above and below eyes, usually terminating before reaching vertex; lateral rugae weaker than those on cephalic dorsum.  Vertex and posterior margin of head weakly granulate-punctate, weakly shining to smooth and shining.  Cephalic interrugal spaces smooth, shining.  Anterior margin of clypeus convex; dorsal surface with 4-8 moderately coarse, subparallel longitudinal rugae; clypeus strongly convex in lateral view.  Mandible with six teeth; mandibular dorsum strongly striated.  MOD ranging from 0.21-0.25x HL.  Eyes in profile situated anterior to middle of head, OMD = 0.57-0.89x MOD; in full-face view, eyes protruding well beyond lateral margins of head.  Antennal scapes long (SI = 79.63-96.00), surpassing vertex by less than length of first funicular segment; scape weakly to moderately granulate-punctate, often with faint striae, weakly shining; basal flange poorly developed with carinate margin.  Psammophore poorly developed, consisting of short to medium length hairs scattered over ventral surface of head.

Mesosomal profile strongly convex; dorsum of mesosoma and sides of pronotum smooth, shining; longitudinal rugae on mesospleura and metapleura wavy to irregular, interrugae weakly to moderately granulate-punctate, weakly shining.  Promesonotal suture usually present, faint to weakly impressed.  Superior propodeal spines moderately long, narrowing to blunt tip, spine length rarely exceeding 0.6-0.7x distance between bases; inferior propodeal spines well developed, triangular, narrowing to blunt to acute tip; a keel-like rugae or crest often connects superior and inferior spines.  Propodeal spiracles narrowly ovate.  Legs smooth weakly granulate, weakly shining to shining. 

      Petiolar peduncle about as long as petiole, anteroventral margin with small, acutely tipped triangular process.  In side view, posterior surface of petiole weakly convex; petiolar node asymmetrical with anterior surface notably shorter than posterior surface, apex of node rounded to bluntly angulate; juncture between anterior face of petiole and peduncle angulate.  In dorsal view, petiole longer than wide, sides subparallel, narrowing to rounded to bluntly angulate anterior margin.  Dorsum of postpetiole convex in profile; in dorsal view, widest near posterior margin, narrowing to anterior margin, maximum width about equal to length; posterior surface and sides of petiole and dorsum and sides of postpetiole smooth and shining; dorsum of gaster smooth and shining.

      Erect copperish-brown, short to long hairs abundant on head, one to few approaching to slightly exceeding MOD.  Moderately abundant subdecumbent to decumbent hairs on antennal scape; abundant decumbent to appressed hairs on funicular segments.  Legs with moderately abundant subdecumbent to decumbent setae.  Mesosoma with moderately dense, medium to long erect seta, longest approaching MOD; petiole, postpetiole, gastral terga with moderately dense erect setae, mostly similar in length, longest notably shorter than MOD.  Body other than gaster mostly concolorous amber-orange to brownish-red, medial portion of cephalic dorsum typically slightly darker than rest of head; gaster dark orangish-black to brownish-black.

Queen

      Diagnosis.  As in worker diagnosis, but with caste-specific morphology of the mesosoma related to wing-bearing, presence of small ocelli on head, and as illustrated in Figure x.  This caste is diagnosed by: (1) small size (HW = 1.05-1.12 mm), (2) mesoscutum and mesoscutellum smooth and shiny, and (3) body orangish-brown, gaster slightly darker.

Measurements - (n = 12). HL 1.21-1.26; HW 1.05-1.12; MOD 0.30-0.33; OMD 0.17-0.24; SL 0.83-0.97; PNW 0.85-0.93; HFL 1.03-1.14; ML 1.52-1.77; PW 0.26-0.33; PPW 0.49-0.54.  Indices: SI 79.05-89.81; CI 83.33-92.56; OI 27.52-30.28; HFI 96.26-106.67.

Male

Diagnosis.  This caste is diagnosed by: (1)

Measurements - (n = 3). HL 1.08-1.22; HW 0.90-1.01; MOD 0.41-0.45; OMD 0.16-0.19; SL 0.28-0.33; HFL 0.98-1.17; ML 1.71-1.75; PW 0.23-0.27; PPW 0.38-0.42.  Indices: SI 29.17-36.67; CI 82.79-85.71; OI 43.75-45.56; HFI 102.08-123.33.

Additional material examined. ARGENTINA: Chubut: Laguna Verde, Feb. 17, 1949 (LACM). Neuquén: Lago Tromen, 1050m, Jan. 9, 1995 (MCZ). Río Negro: Bariloche, Jun. 2, 1949 (LACM; MCZ; MLPA; USNM); Laguna Frías, 760m, Nov. 16, 1966 (CASC); Victoria Bariloche, Jan. 15, 1972 (LACM). CHILE: Araucanía (Malleco)*: Parque Nacional Nahuelbuta, Dec. 14, 1972 (LACM).

*The primary administrative division in Chile changed from province to region in the mid-1970’s.  Most additional material examined was collected when provinces were the primary division (e.g., Snelling & Hunt, 1975).  Consequently, I list older collections by region followed by province (in parentheses) so as to link current regions with previous province names.

 

Etymology.  In his description, Kusnezov did not give information regarding the naming of this species.  However, Kunezov (1960) indicated that the name was derived from the odor emitted by the species.

Discussion.  Pogonomyrmex odoratus co-occurs with P. angustus and P. laevigatus.  Pogonomyrmex odoratus can be distinguished from P. angustus based on the following characters: (1) dorsum of mesosoma and posterior face of petiole smooth and shining (both structures are strongly granulate in P. angustus), and (2) body mostly concolorous amber-orange to brownish-red, gaster dark orangish-black to brownish-black (P. angustus is mostly concolorous dark brownish-black to nearly black).  In his key, Kusnezov (1951) separated P. odoratus from P. laevigatus based on: (1) color (body an orangish-brown with the gaster slightly darker in P. odoratus, mostly concolorous blackish to black in P. laevigatus), and (2) shape of the juncture between the anterior surface of the petiole and peduncle, which is angulate in P. odoratus and rounded in P. laevigatus.  Kusnezov (1949, 1951) also indicated that longitudinal cephalic rugae were less coarse in P. odoratus than in P. laevigatus, but I did not discern this difference.

Pogonomyrmex odoratus is distinguished from other congeners by the poorly developed psammophore and the smooth and shiny dorsum of the mesosoma.  All other congeners have a well developed psammophore and/or the dorsum of the mesosoma is rugose.

REFERENCES

Kusnezov, N. (1949) Pogonomyrmex del grupo Ephebomyrmex en la fauna de la Patagonia (Hymenoptera, Formicidae). Acta Zoologica Lilloana, 8, 291-307.

Kusnezov, N. (1951) El género Pogonomyrmex Mayr (Hym., Formicidae). Acta Zoologica Lilloana, 11, 227-333.

Kusnezov, N. (1960) La fauna de hormigas en el oeste de la Patagonia y Tierra de Fuego. Acta Zoologica Lilloana, 17, 321-401.

Snelling, R.R. & Hunt, J.H. (1975) The ants of Chile (Hymenoptera: Formicidae). Revista Chilena de Entomologia, 9, 63-129.