Pheidole glabrella, FISCHER & GARCIA & PETERS, 2012

FISCHER, GEORG., GARCIA, FRANCISCO HITA & PETERS, MARCELL K., 2012, Taxonomy of the ant genus Pheidole Westwood (Hymenoptera: Formicidae) in the Afrotropical zoogeographic region: definition of species groups and systematic revision of the Pheidole pulchella group, Zootaxa 3232 (1), pp. 1-43 : 26-28

Pheidole glabrella sp. n.

( Figures 36–41 )

Holotype: (major worker) CAMEROON, Ebodije , 4.xi.91 (A. Dejean) ( BMNH: CASENT0227950 ). Paratypes: (2 major workers, 6 minor workers) same data as holotype ( BMNH: CASENT0 227951, CASENT0 227952, CASENT0227953).

Diagnosis: Color reddish brown to dark brown. Minor workers: head shape broadly rounded, with rounded to slightly compressed posterior head margin (CI: 88–95). Scapes short to moderately long (SI: 123–141) with appressed to decumbent pilosity. Promesonotum and parts of meso- and metapleuron smooth and shiny to superficially punctate, second mesonotal process usually shallow, spines relatively long and massive (PSLI: 28–40). Pilosity on metatibia mostly appressed, standing hairs scarce to practically absent from dorsum of entire body, completely absent from mesosoma. Major workers: head irregularly rugose-punctate, rugae of varying lengths, punctures weak to superficial with smooth areas between rugae. Scapes relatively short (SI: 49–53), with appressed pilosity. Pronotum irregularly and transversely rugulose, declivity smooth and shiny. Metanotal groove broad, in profile view, dorsopropodeum anterior to propodeal spines shorter than horizontal width of base of spines. Metatibia pilosity fully appressed, standing hairs rare, absent from mesosoma.

Description of minor worker: Measurements (n=26): HL: 0.722–0.922 (0.851), HW: 0.667–0.856 (0.779), SL: 0.876–1.133 (1.022), MDL: 0.511–0.633 (0.576), EL: 0.167–0.194 (0.181), MFL: 1.044–1.349 (1.224), MTL: 0.789–1.044 (0.951), WL: 1.011–1.286 (1.162), PSL: 0.200–0.356 (0.282), PTH: 0.167–0.206 (0.185), PPH: 0.183–0.239 (0.212), PTL: 0.267–0.367 (0.336), PPL: 0.178–0.233 (0.198), PTW: 0.106–0.133 (0.121), PPW: 0.183–0.267 (0.225), PW: 0.456–0.557 (0.506); CI: 88–95 (92), SI: 123–141 (131), MDI: 71–78 (74), PSLI: 28–40 (33), PWI: 61–68 (65), FI: 143–170 (157), PpWI: 165–210 (186), PpLI: 142–206 (170).

Head shape in full-face view posterior of eyes roundly convex to compressed, posterior margin rounded to weakly flat (CI: 88–95). Occipital carina narrow, mandibles smooth and shiny dorsally. Clypeus without or rarely with short submedian carinae and with inconspicuous and short lateral carinae. Face smooth with hexagonal microsculpture, weakly to superficially punctate laterally near eyes, malar carinae weak, disappearing posterior of eyes. Scape, when laid back, surpassing posterior head margin by more than one quarter of its length (SI: 123–141) and with appressed to decumbent pilosity. Promesonotum in lateral view flat and subangular, completely smooth and shiny to superficially punctate. First mesonotal process conspicuously produced, with worn appearance, due to complete lack of sculpture, other than hexagonal microsculpture. Second process shallow and worn, very rarely more conspicuous. Mesopleuron and propodeum weakly to superficially punctate to almost smooth, intensity also varying with viewing-angle. Episternum, anterior lateropropodeum, and dorsopropodeum often with smooth spots, metapleural carina and gland scrobe developed. Spines mostly very long (PSLI: 28–40), relatively massive basally, short rugulae radiating medially and posteroventrally from their bases. Metanotal groove conspicuously U-shaped in lateral view. Metafemur moderately to relatively long (FI: 143–170), metatibial pilosity appressed. Petiole and postpetiole punctate laterally and ventrally, peduncle and nodes dorsally polished smooth. First gastral tergite shagreened anteriorly, grading to smooth and shiny posteriorly. Mesosoma lacking long standing hairs dorsally, but moderately long hairs present on posterior end of gaster, in some specimens also on anterior gaster and on head. Head or postpetiole or both with additional appressed inconspicuous pubescence, sometimes with very few short decumbent to subdecumbent hairs. Color reddish brown, appendages and head margin near lateral base of mandibles in lighter shade.

Description of major worker: Measurements (holotype): HL: 1.800, HW: 1.800, SL: 0.956, MDL: 0.778, EL: 0.222, MFL: 1.397, MTL: 1.067, WL: 1.349, PSL: 0.311, PTH: 0.300, PPH: 0.333, PTL: 0.489, PPL: 0.300, PTW: 0.200, PPW: 0.411, PW: 0.744; CI: 100, SI: 53, MDI: 43, PSLI: 17, PWI: 41, FI: 78, PeI: 27, PpI: 55, PpWI: 206, PpLI: 163.

Measurements (n=5): HL: 1.820–2.125 (1.974), HW: 1.840–2.150 (2.015), SL: 0.944–1.078 (1.024), MDL: 0.778–0.967 (0.878), EL: 0.228–0.267 (0.246), MFL: 1.429–1.635 (1.537), MTL: 1.089–1.270 (1.192), WL: 1.381–1.619 (1.524), PSL: 0.311–0.367 (0.342), PTH: 0.300–0.356 (0.333), PPH: 0.344–0.444 (0.392), PTL: 0.467–0.567 (0.536), PPL: 0.311–0.344 (0.329), PTW: 0.200–0.261 (0.232), PPW: 0.428–0.544 (0.483), PW: 0.800–0.944 (0.880); CI: 99–105 (102), SI: 49–53 (51), MDI: 42–45 (44), PSLI: 16–18 (17), PWI: 42–44 (44), FI: 75–79 (76), PeI: 24–28 (26), PpI: 50–59 (55), PpWI: 186–222 (209), PpLI: 145–170 (163).

Some rugae on frons long and others short or interrupted, posterolateral lobes weakly and obliquely rugulosepunctate to smooth on corners or weakly reticulate. Sides of head laterally of antennal scrobe weakly rugose-reticulate or irregularly rugose, punctures weak to superficial and sometimes smooth areas present between sculpture. Scapes relatively short (SI: 49–53), with appressed pilosity. Promesonotum in lateral view in some specimens short, dorsally nearly flat and posteriorly slightly compressed, with steep and long declivity, in other specimens longer and rounding into posterior declivity. Anteropronotum dorsally and laterally with irregularly distributed transverse rugulae, in between with weak to superficial punctures, grading to smooth and shiny promesonotal declivity dorsally and posteropronotum laterally. Humeral area laterally weakly processed and angulate, mesonotal process shallow to well-produced, dorsally smooth with oblique angle or right-angled and steeply declining. Second mesonotal process inconspicuous, at most visible as weak ridge, metanotal groove broad and shallow. Dorsopropodeum very short and in profile view anterior to propodeal spines significantly shorter than horizontal width of base of spines, weakly punctate, but with dense punctures lateroventrally. Meso- and metapleuron weakly to superficially punctate, smooth and shiny around metapleural carina, metapleural gland scrobe absent or inconspicuous. Transverse rugula(e) present posteriorly between spines, posteropropodeum otherwise weakly punctate. Metatibia with fully appressed pilosity. Petiole (except anterodorsally) and postpetiole punctate to weakly punctate, the latter posterodorsally with weak irregular rugulae. First gastral tergite shagreened, posteriorly hexagonally microsculptured. Long standing hairs very rare on head, postpetiole and dorsal gaster, their apices blunt or truncate, on mesosoma completely absent. Color reddish brown, gaster dark brown.

Discussion: Minor and major workers show a relatively great degree of variability in size and sculpture, especially between the type specimens from Cameroon and the material from the Central African Republic and Gabon. Minors from the Central African Republic differ from the types in a more variable sculpture on the mesonotum, mesopleuron and propodeum. The latter is almost smooth in some specimens versus strongly punctate in others. The minor workers of the type series possess a smooth mesonotum and superficially sculptured mesopleuron and propodeum. Majors from Gabon are differentiated from the type majors by the absence of punctate sculpture between the rugae on the head, and in lateral view a longer, rounded promesonotum. They are also more than 10 percent larger than the majors from the type series, although the indices are not significantly different between the two populations. Other than these differences, all specimens share the same morphometric profile and overall habitus. This, and the fact that intermediate forms are present in the minor subcaste, is in support of a one-species hypothesis. Still, there is a small probability that the different populations could turn out to be heterospecific, if more material from other sites and particularly from the major worker subcaste becomes available.

The species most similar to Pheidole glabrella is P. rebeccae . The minor workers of the latter are separated from those of the former by a slightly less convex posterior head margin, and shorter scapes (SI: 114–121 versus SI: 123–141), spines (PSLI: 25–30 versus PSLI: 28–40) and legs (FI: 133–139 versus FI: 143-170). The major workers of P. rebeccae differ from those of P. glabrella by longer and uninterrupted rugae in the face, a narrow versus broad metanotal groove, and significantly more standing hairs on all dorsal surfaces, except the propodeum. P. glabrella has a West to Central African distribution, from Cameroon to the D.R. Congo, where several minor workers were collected by the American Museum Congo Expedition together with and included in the type series of P. batrachorum . The other material has been collected in rainforests from sifted leaf-litter, rotten logs, and beating of the lower vegetation.

Additional material examined: CAMEROON: (7 minor workers) Prov. Sud, P.N. Campo, 43.3 km 108° ESE Campo, 290 m, 7.iv.2000, 02° 17.0’ N, 10° 12.4' E (B.L. Fisher) ; (1 minor worker) Mbalmayo, xi.1993 (N. Stork) ; CENTRAL AFRICAN REPUBLIC: (1 minor worker) Reserve Dzanga-Sangha, 12.7 km 326° NW Bayanga, 03° 00.27' N, 16° 11.55' E, 420 m, 11–17.v.2001 (S. van Noort) ; (2 minor workers) P.N. Dzanga-Sangha, 38.6 km 173° S Lidjombo, 02° 21.60' N, 16° 03.20' E, 350 m, 21–27.v.2001 (S. van Noort) ; (1 minor worker) P.N. Dzanga-Ndoki, 21.4 km 53° NE Bayanga, 03° 02.01' N, 16° 24.57' E, 510 m, 3.v.2001 (S. van Noort) ; (5 minor workers) Reserve Dzanga-Ndoki, Mabea Bai, 21.4 km 53° NE Bayanga, 03° 02' N, 16° 25' E, 510 m, 1–07.v.2001 (B.L. Fisher) ; (2 minor workers) Reserve Dzanga-Ndoki, 37.9 km 169° S Lidjombo, 02° 22' N, 16° 10' E, 360 m, 21.v.2001 (B.L. Fisher) ; (1 minor worker) Reserve Dzanga-Sangha, 12.7 km 326° NW Bayanga, 03°00' N, 16° 12' E, 470 m, 10–17.v.2001 (B.L. Fisher) ; D.R. CONGO: (5 major workers, among syntypes of P. batrachorum ) Akenge (H.O. Lang) ; GABON: (2 minor workers) Prov. Ogooue Maritime, Reserve Moukalaba, 12.2 km 305° NW Doussala, 110 m, 02° 17.0' S, 10°29.8' E, 24.ii.2000 (B.L. Fisher) ; (5 minor workers) Prov. Woleu-Ntem, 31.3 km 108° ESE Minvoul, 02° 04.8' N, 12° 24.4' E, 600 m, 12.ii.1998 (B.L. Fisher) ; (2 major workers, 4 minor workers) Prov. Ogooue Maritime, Reserve Monts Doudou Moukalaba, 12.2 km 305° NW Doussala, 110 m, 02° 17.0' S, 10° 29.8' E, 24.ii.–3.iii.2000 (B.L. Fisher) ; (1 minor worker, 1 major worker) Prov. Ogooue Maritime, Reserve Monts Doudou, 25.2 km, 304° NW Doussala, 02° 13.60' S, 10° 23.70' E, 14.iii. 2000, 640 m (B.L. Fisher) .

Figures

FIGURE 36 – 41: P. glabrella sp. n.: full-face, lateral & dorsal view of minor (Fig. 36 – 38) (Cameroon, CASENT 0227951) and major worker (Fig. 39 – 41) (Cameroon, CASENT 0227950).