Polyergus ruber, Trager, James C., 2013

Trager, James C., 2013, Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini), Zootaxa 3722 (4), pp. 501-548 : 528-529

Polyergus ruber new species

Figures 39, 40, 41

Polyergus lucidus longicornis: Vargo and Gibbs 1987 (misidentification).

Holotype worker: USA, GEORGIA Clark Co. Athens. 165 Doe Run. [CAS, CASENT0281055] Paratypes: 4 workers, 3 gynes, 3 males: Same data as holotype [MCZ, CAS].

Holotype measurements HL 1.90, HW 1.80, SL 1.79, ½ VeM 9, ½ PnM 3, WL 2.86, GL 2.60, HFL 2.44, CI 95, SI 99, HFI 136, FSI 136, LI 4.76, TL 7.36.

Paratype measurements (N=5) [MCZ, CAS, FSCA] HL 1.60–1.90 (1.75), HW 1.52–1.80 (1.64), SL 1.68–1.79 (1.71), ½ VeM 3–9 (6.8), ½ PnM 1–4 (2.2), WL 2.52–2.86 (2.66), GL 2.04–2.60 (2.34), HFL 2.09–2.44 (2.26), CI 93–95 (94), SI 99–113 (105), HFI 134–146 (138), FSI 124–136 (132), LI 4.12–4.76 (4.41), TL 6.16–7.36 (6.75).

Measurements (N=26) HL 1.52–1.90 (1.65), HW 1.42–1.80 (1.64), SL 1.68–1.79 (1.71), ½ VeM 3–9 (6.8), ½ PnM 1–4 (2.2), WL 2.52–2.86 (2.66), GL 2.04–2.60 (2.34), HFL 2.09–2.44 (2.26), CI 93–95 (94), SI 99–113 (105), HFI 124–136 (132), FSI 124–136 (132), LI 4.12–4.76 (4.41), TL 6.16–7.36 (6.75).

Worker description. This species is most similar to longicornis , but is shinier and has less pilosity. Head rectangular to weakly hexagonal, HL greater than HW; with conspicuous vertex pilosity consisting of (5) 8–20 erect macrosetae; scapes at least reaching, normally surpassing vertex corners, gradually thickening in distal half; pronotum with 0–6 dorsal erect setae; mesonotal profile weakly convex for most of its length; propodeal profile variable ranging from evenly rounded to a weakly obtuse, rounded angle; petiole narrow, sides convex and converging dorsad, petiolar dorsum rounded or with median portion flat, less often feebly concave; first tergite lacking pubescence; first tergite pilosity sparse, weakly flexuous or straight.

Head matte to very faintly shining; mesosoma matte dorsally but shining laterally; gaster weakly shining to shiny.

Discussion. This is among the three largest species of the lucidus group, almost in the same size range as longicornis , but characterized by a shinier head and mesosoma, especially the pronotum, and less abundant pilosity, especially on the vertex. Color is clear red with at most slight infuscation of the extremities.

P. r u b e r appears intermediate between longicornis and lucidus in its proportions, pilosity, and shininess. The sheen and lesser vertex pilosity distinguishes ruber from the more matte longicornis ( ruber ½ VeM <12 vs. longicornis > 13) while the longer appendages distinguish it from lucidus ( ruber SI> 92+ vs. lucidus <91).

Etymology. With the name ruber, Latin for red or ruddy, I refer to the brighter, all-red color of this ant species, in comparison to other southeastern species, especially the somewhat similar, but dark-legged longicornis .

Natural history. Polyergus ruber tracks its host, F. biophilica , in distribution, namely, a U-shaped range south from Maryland to Georgia, west to Louisiana, then north to eastern Missouri. It would be unsurprising if this ant showed up from collecting in at least southern Illinois.

Polyergus ruber was studied by Vargo and Gibbs (1987, reported as lucidus longicornis ) in Athens, GA. Aside from its unique host association, ruber seems much like its relatives in the lucidus group in most respects. Raids were observed from early June to mid-August, and may have continued after these observations ended, as the activity was still vigorous, so perhaps starting just a few weeks earlier and persisting perhaps a bit longer than in other species of the group. I observed parts of a raid, and a mating flight that occurred several hours before the raid, in Georgia, and two raids of these ants in Missouri, all in July, and they are much like those of the other species. At both locations, pre-raiding milling was initiated around 1700 hr. The size of raiding parties in the Georgia colonies was estimated between 500 and 1000, quite large compared to other known lucidus group species. Colonies and raiding parties were somewhat smaller in Missouri. Vargo and Gibbs observed dealate gynes near the outskirts of nests before raids in late July, and saw one of these follow a raid and enter the raided nest. Habitats of this species included a variety of upland, grassy and open woodland types, with acid soils.

Distribution of studied specimens. GEORGIA Clarke Co. Athens. 165 Doe Run. Flight at noon. Raid at 1930hr. 10 July 1986 J. C. Trager (JCT) GEORGIA Clarke Co. Athens USA UGA Riverbend Lab. 3–11 July 1986 E. Vargo, JC Trager (JCTC); LOUISIANA St. Tammany Par. Lake Ramsey WMA SC3-3 Longleaf pine savanna. Pitfall trap. D Colby (multiple collections July–October 1997, LSU); MARYLAND Prince Georges Co. Berwyn [Heights] 6-25-1940 AB Gahas. W S Ross Coll. (FMNH); MISSISSIPPI Chickasaw Co. Tombigbee Nat’l Forest 33o55’39”N / 88 o50’57”W 20-27-June 2003 J. G. Hill (MEM); MISSOURI Lincoln Co. Cuivre River St. Pk. Sac Prairie 20 Apr. 1989 J.C. Trager (JCTC); NORTH CAROLINA Canover 1-VIII-32 Vanderford (NCSU); NORTH CAROLINA Burke Co. Morganton On ground 10-VI-1989 H. Barron (NCSU); NORTH CAROLINA Raleigh Raiding Nest 7-VII-1987 DL Stephan (NCSU); NORTH CAROLINA Granville Co. Oxford 1-VII-1977 F. Sutherland (NCSU); NORTH CAROLINA Durham Co. Durham K. Hedlund (no date) (NCSU); NORTH CAROLINA Wake Co. Cary June 10, 1984 DL Stephan (NCSU); NORTH CAROLINA Gaston Co. NE Cherryville Sept. 6, 1983 PJ Devine (NCSU).

Figures

FIGURES 39 – 41. Lateral, full face, and dorsal views of Polyergus ruber worker CASENT 0281055. Photographs by Shannon Hartman from www. AntWeb. org.