Pheidole jonas Forel

FISCHER, G. & FISHER, B. L., 2013, 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, Zootaxa 3683 (4), pp. 301-356 : 325-328

Pheidole jonas Forel

( Figs. 18A–F )

Pheidole jonas Forel, 1907c: 82 .

Lectotype (1 major worker, CASENT0101758 ) [designated here]: COMORO ISLANDS (Grande Comore) (A. Voeltzkow) ( MHNG) [examined] ; paralectotypes (1 major workers & 3 minor workers, CASENT0101758 , CASENT0101689 ) same data as lectotype (MHNG) [examined].

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).

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 longitudinal rugae, sides of head irregularly longitudinally rugose to weakly rugoreticulate, head posterior 1/3 irregularly rugoreticulate, ventrally weakly to superficially punctate. Submedian hypostomal teeth large and very conspicuous in profile view, median process absent. Scapes relatively short (SI 47–56) with decumbent pilosity and few longer erect to suberect standing hairs on outer edge. Promesonotal dome high, strongly convex, rounded to angulate anteriorly, promesonotal process in profile short with shallow, concave groove and situated low at mesonotum, posteriorly bluntly angulate with vertical declivity toward metanotal groove, in dorsal view with humeri not produced laterally. Dorsal surface of promesonotum punctate to very weakly punctate, additionally weakly rugoreticulate or with irregular transverse rugulae, rest of mesosoma punctate, often with slightly reduced sculpture basally on katepisternum and propodeum. Metanotal groove not impressed, cross-ribs mostly short, weakly developed, with superficially punctate interspaces. Spines short-spinose to subtriangular (PSLI 10–14), distinctly shorter than distance between their bases. Metafemur moderately short (FI 61–75), metatibia pilosity decumbent, on outer edge also with few longer, suberect hairs. Petiole in dorsal view anteriorly wider with prominent lateral process, postpetiole in profile usually longer than high (LPpI mean 109), ventral process absent, in dorsal view with short to relatively long lateral processes, between two and three times wider than petiole (PpWI 218–300). Petiole and postpetiole punctate everywhere, postpetiolar dorsum sometimes superficially sculptured. First gastral tergite anteriorly weakly punctate to micropunctate. Standing hairs on mesosoma and metasoma acute, long, and slender, only moderately abundant, shorter on head, and with interspersed shorter decumbent to subdecumbent pilosity. Whole body orange with yellow to dark brown legs.

Description of minor workers: Measurements (n=16): HW 0.37–0.50 (0.46), HL 0.45–0.57 (0.51), SL 0.44– 0.55 (0.50), MDL 0.26–0.33 (0.30), EL 0.08–0.11 (0.09), WL 0.53–0.69 (0.60), PNH 0.21–0.28 (0.23), PNW 0.27– 0.34 (0.30), MNH 0.34–0.48 (0.41), PDH 0.17–0.22 (0.20), PTL 0.18–0.26 (0.22), PPL 0.11–0.16 (0.13), PTH 0.11–0.13 (0.12), PPH 0.08–0.11 (0.09), PTW 0.07–0.10 (0.08), PPW 0.11–0.15 (0.13), PSL 0.06–0.09 (0.07), MFL 0.45–0.61 (0.53), MTL 0.34–0.49 (0.40), CI 83–94 (90), SI 102–122 (109), MDI 60–73 (66), EI 19–23 (21), FI 107–122 (116), PSLI 12–17 (15), LPpI 122–163 (144), DPpI 88–109 (97), PpWI 133–175 (155), PpLI 52–74 (61), PpHI 73–83 (77).

Head subrectangular, slightly longer than wide (CI 83–94), sides convex, posterior head margin weakly concave medially, occipital carina invisible in full-face view. Mandibles moderately short (MDI 60–73), smooth and shiny. Clypeus smooth to superficially punctate, carinae absent. Face completely punctate, malar carinae faintly developed toward posterior eye level. Scapes short (SI 102–122), when laid back surpassing posterior head margin by length of 10 th funicular segment, pilosity mostly subdecumbent to suberect. Promesonotal outline in profile convex, weakly elongated, often subangulate anteriorly and posteriorly, posterior process absent to inconspicuous. Metanotal groove barely to shallowly impressed, cross-ribs conspicuous to superficial with smooth interspaces. Propodeum in profile about slightly higher than long, highest point immediately after metanotal groove, propodeal spines short subtriangular, significantly shorter than distance between their bases (PSLI 12–17). Mesosoma punctate to weakly punctate. Metafemur short (FI 107–122), metatibia with decumbent to subdecumbent pilosity. Postpetiole significantly longer than high (LPpI 122–163), about as long as wide (DpPI 88– 109), lower than petiole (PpHI 73–83), and without ventral process. Both waist segments superficially to weakly punctate. Gaster smooth and shiny. Standing hairs moderately short, comparatively scarce on mesosoma and metasoma, stiff and acute, shorter pilosity more abundant, decumbent to subdecumbent. Color orange or brown.

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 MDI 54–63, SI 96–106, LPpI 114–120 in P. vulcan ), while the majors have a lower promesonotal process with a conspicuously concave transverse groove in profile view. Standing hairs are significantly less abundant and less flexuous in both worker castes than in those of P. vulcan . The minor workers of P. loki (majors are unknown) can be easily distinguished from the two other species, as the scapes are on average longer (SI 117–122) and the sculpture on dorsal head and mesosoma is largely reduced, whereas the heads and mesosomas of P. jonas and P. vulcan possess comparatively strong punctures.

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.xi.2007 (B.L. Fisher et al.); Mont Combani , 12.8063 S, 45.1531 E, 370 m, rainforest, 25.xi.2007 (B.L. Fisher et al.); Mont Combani, 12.8049 S, 45.1527 E, 460 m, rainforest, 29.xi.2007 (B.L. Fisher et al.); Mt. Combani , 12.8 S, 45.1333 E, 470 m / 420 m, forest litter, 22.ii.1999 (R. Jocque & G. DeSmet); Reserve Forestière Majimbini , 12.7689 S, 45.1902 E, 350 m, rainforest, 03.xii.2007 (B.L. Fisher et al.); Reserve Forestière Majimbini, 12.768 S, 45.1861 E, 525 m, rainforest, 03.xii.2007 (B.L. Fisher et al.); Reserve Forestière Sohoa , 12.8059 S, 45.1005 E, 20 m, coastal scrub, rainforest, 29.xi.2007 (B.L. Fisher et al.).

Figures

FIGURE 18 Pheidole jonas Forel, full-face view (A), profile (B), and dorsal view (C) of minor worker (CASENT006581) and full-face view (D), profile (E), and dorsal view (F) of major worker (CASENT0060250).