Pheidole jonas

description

Description of major workers: Measurements (n = 16): HW 0.96 – 1.18 (1.06), HL 0.98 – 1.18 (1.07), SL 0.47 – 0.60 (0.56), MDL 0.45 – 0.59 (0.52), EL 0.11 – 0.16 (0.13), WL 0.79 – 0.95 (0.87), PNH 0.39 – 0.47 (0.43), PNW 0.45 – 0.55 (0.50), MNH 0.59 – 0.73 (0.65), PDH 0.27 – 0.35 (0.30), PTL 0.28 – 0.42 (0.35), PPL 0.18 – 0.22 (0.20), PTH 0.17 – 0.22 (0.21), PPH 0.16 – 0.21 (0.19), PTW 0.13 – 0.17 (0.15), PPW 0.32 – 0.46 (0.38), PSL 0.11 – 0.14 (0.12), MFL 0.65 – 0.81 (0.74), MTL 0.45 – 0.60 (0.54), CI 95 – 102 (99), SI 47 – 56 (52), MDI 45 – 51 (49), EI 11 – 14 (12), FI 61 – 75 (70), PSLI 10 – 14 (12), LPpI 90 – 126 (109), DPpI 152 – 242 (188), PpWI 218 – 300 (256), PpLI 50 – 64 (57), PpHI 83 – 106 (90). Head about as wide as long (CI 95 – 102), sides weakly convex, posterior emargination comparatively shallow, weakly V-shaped. Mandibles short (MDI 45 – 51), smooth, and shiny, with very few short rugulae laterobasally. Clypeus smooth, posteromedially often with weakly developed, sometimes anteriorly converging carinae, median carina absent, 2 pairs of lateral carinae present. Frontal carinae very short or inconspicuous, antennal scrobe absent. Face weakly punctate, anteriorly with

A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala

diagnosis

Diagnosis: Small species (WL major 0.79 – 0.95 mm, WL minor 0.53 – 0.69 mm), minor workers with moderately short scapes and legs (SI 102 – 122, FI 107 – 122), major workers with moderately short legs (FI 61 – 75), in both subcastes standing hairs comparatively sparse on mesosoma. Major head posterior half irregularly rugoreticulate, submedian hypostomal teeth large, median process absent, promesonotal process short with shallowly concave groove and almost vertical posterior declivity, spines short-spinose to almost triangular (PSLI 10 – 14), postpetiole higher than long (LPpI 83 – 95), without ventral process, but with prominent lateral process and thus on average 2.5 times as wide as petiole. Minor workers head subrectangular and punctate, clypeus smooth to superficially punctate, median and lateral carinae absent, mesosoma regularly punctate, often with weak irregular rugulae on pronotum, spines short-subtriangular (PSLI 12 – 17), postpetiole on average 1.4 times longer than high (LPpI 122 – 163).

A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala

discussion

Discussion: Pheidole jonas is known only from the Comoros Islands and Mayotte. It was collected mostly from rainforest leaf litter, but also from rotten logs, under moss, and above ground in rainforest and montane rainforest in elevations between 20 and 1235 m. The populations on Anjouan, Grand Comore, and Mayotte islands are morphologically distinct, but share enough characteristics with each other and with the original type material to be identified as a single species, until further research proves otherwise. The specimens from Anjouan are all orange in color, like the types, whereas those from the other two islands are brown. The Grand Comore and Mayotte populations can be distinguished further by minor allometric differences in the head, pronotum and postpetiole. The majors from Grand Comore tend to have a slightly wider head (CI 99 – 102 versus CI 95 – 98) and a wider postpetiole (PpWI 218 – 267 versus PpWI 279 – 300) than those from Mayotte. P. jonas is probably closely related to P. vulcan and P. loki. The minor workers of P. jonas can be separated from those of P. vulcan by slightly longer mandibles, scapes, and postpetiole (MDI 60 – 73, SI 102 – 122, LPpI 122 – 163 versus

A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala

materials_examined

Additional material examined: COMOROS: Anjouan: Lac Dzialandee, 12.2247 S, 44.4312 E, 900 m, disturbed montane rainforest, 25. i. 2009 (B. L. Fisher et al.); Mount Ntringui, 12.2204 S, 44.4292 E, 1225 m, montane forest, 24. i. 2009 (B. L. Fisher et al.); Grande Comore: Karthala, 11.8134 S, 43.4194 E, 1125 m, montane rainforest, 13. iii. 2008 (B. L. Fisher et al.); Karthala, 11.827 S, 43.4295 E, 1000 m, montane rainforest, 14. iii. 2008 (B. L. Fisher et al.); Karthala, 11.7533 S, 43.3079 E, 1235 m, montane rainforest, 17. iii. 2008 (B. L. Fisher et al.); Mohéli: Ouallah, 12.3067 S, 43.6641 E, 275 m, rainforest, 21. i. 2009 (B. L. Fisher et al.); MAYOTTE: Coconi, DAF Campus, 12.8333 S, 45.1333 E, 15. i. 1999 (R. Jocque & G. DeSmet); Coconi, SDA (Service de Developpement Agricole), 12.8333 S, 45.1333 E, wet area with giant bamboo, 18. ii. 1999 (R. Jocque & G. DeSmet); Dapani, 12.9628 S, 45.1504 E, 135 m, rainforest, 02. xii. 2007 (B. L. Fisher et al.); Mont Benara, 12.8758 S, 45.1567 E, 425 m, rainforest, 30. xi. 2007 (B. L. Fisher et al.); Mont Chongui, 12.9578 S, 45.134 E, 470 m, rainforest, 28. xi. 2007 (B. L. Fisher et al.); Mont Chongui, 12.959 S, 45.1341 E, 380 m, rainforest, 28

A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala