Pheidole rebeccae, 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 : 35-38

Pheidole rebeccae sp. n.

( Figures 57–62 )

Holotype: (major worker) IVORY COAST, vic. Abidjan, 1976, no. 15 (T. Diomande) ( BMNH: CASENT0227954 ). Paratypes: (3 major workers, 8 minor workers) same data as holotype ( BMNH: CASENT0227955, CASENT0227956, CASENT0227957, CASENT0227958).

Diagnosis: Color reddish brown (major) to brown (minor). Minor workers: head shape rounded, almost as broad as long (CI: 94–98), posterior margin compressed to almost straight. Scapes short (SI: 114–121), pilosity mostly decumbent. Most dorsal surfaces superficially punctate (sides of head, propodeum, anterior gaster) to smooth and shiny (posterior head margin, promesonotum, waist segments partly). Metafemur relatively short (FI: 133–139), metatibia pilosity decumbent. Major workers: head and promesonotum with short and weak superficial rugulae, posteriorly largely smooth and shiny. Sculpture on meso- and metapleuron also reduced, with several smooth spots. Metanotal groove barely impressed in lateral view and length of dorsopropodeum anterior to propodeal spines equal to horizontal width of base of spine. Standing hairs abundant, but absent from propodeum, sometimes also from rest of mesosoma.

Description of minor worker: Measurements (n=11): HL: 0.756–0.811 (0.785), HW: 0.717–0.778 (0.754), SL: 0.856–0.900 (0.885), MDL: 0.511–0.556 (0.531), EL: 0.167–0.178 (0.171), MFL: 0.967–1.067 (1.024), MTL: 0.756–0.867 (0.809), WL: 1.011–1.078 (1.035), PSL: 0.194–0.233 (0.217), PTH: 0.167–0.178 (0.170), PPH: 0.183–0.206 (0.194), PTL: 0.267–0.333 (0.303), PPL: 0.189–0.222 (0.197), PTW: 0.106–0.111 (0.110), PPW: 0.189–0.217 (0.204), PW: 0.456–0.500 (0.475); CI: 94–98 (96), SI: 114–121 (117), MDI: 69–73 (70), PSLI: 25–30 (28), PWI: 62–64 (63), FI: 133–139 (136), PpWI: 170–195 (185), PpLI: 133–176 (154).

Head shape in full-face view compactly rounded, posterior margin of head compressed to almost straight. Occipital carina narrow, mandibles relatively short (MDI: 69–73). Clypeus smooth, with two very faint median carinae, lateral carinae usually more strongly developed. Face smooth and shiny with faint hexagonal microstructure. Malar carinae short, ending at midlevel of eyes. Scapes relatively short, shortest within group (SI: 114–121), pilosity decumbent, partly subdecumbent to suberect apically. Promesonotum smooth and shiny, without sculpture, mostly without standing hairs, but occasionally with two pairs of long, blunted hairs on anterior corners of humeral area or one pair on Humeri. Meso- and metapleuron weakly to superficially punctate, katepisternum and anterior metapleuron with smooth central spots. First mesonotal process conspicuous, roundly angulate. Second process reduced to a shallow, obliquely angulate projection or ridge, metanotal groove wide and deep. Dorsopropodeum weakly punctate, descending smoothly from highest point after metanotal groove towards propodeal declivity. Propodeal spines relatively short (PSLI: 25–30) and slender, almost straight to well-curved posteriorly. Metafemur relatively short, shorter than in other species from this group (FI: 133–139), metatibial pilosity decumbent. Petiole and postpetiole weakly punctate laterally and ventrally, dorsally smooth and shiny. Anterior half of first gastral tergite shagreened, rest smooth, hexagonally microsculptured or whole gaster weakly punctate. Long standing hairs often truncated, present on head, postpetiole and gaster, number on dorsal head variable, up to five pairs, absent to very scarce on mesosoma and petiole, both usually with shorter decumbent hairs. Pubescence inconspicuous, mostly fine and appressed. Color brown, mandibles and appendages lighter.

Description of major worker: Measurements holotype: HL: 1.960, HW: 1.980, SL: 0.978, MDL: 0.911, EL: 0.250, MFL: 1.476, MTL: 1.133, WL: 1.556, PSL: 0.278, PTH: 0.333, PPH: 0.411, PTL: 0.556, PPL: 0.344, PTW: 0.239, PPW: 0.522, PW: 0.900; CI: 101, SI: 49, MDI: 46, PSLI: 14, PWI: 45, FI: 75, PeI: 27, PpI: 58, PpWI: 219, PpLI: 161.

Measurements (n=3): HL: 1.820–1.980 (1.900), HW: 1.860–1.960 (1.927), SL: 0.944–0.967 (0.956), MDL: 0.833–0.889 (0.859), EL: 0.233–0.267 (0.256), MFL: 1.476–1.556 (1.503), MTL: 1.078–1.122 (1.104), WL: 1.444–1.524 (1.487), PSL: 0.244–0.300 (0.278), PTH: 0.322–0.344 (0.337), PPH: 0.361–0.400 (0.378), PTL: 0.467–0.500 (0.489), PPL: 0.311–0.356 (0.330), PTW: 0.211–0.233 (0.226), PPW: 0.456–10.533 (0.493), PW: 0.856–0.900 (0.881); CI: 99–103 (102), SI: 49–51 (50), MDI: 42–45 (44), PSLI: 13–16 (15), PWI: 45–46 (46), FI: 75–84 (78), PeI: 25–26 (26), PpI: 53–59 (56), PpWI: 210–229 (218), PpLI: 141–161 (149).

Frons with relatively weak, irregular, very short or interrupted rugae, spaces between rugae superficially punctate, only a narrow, sculptured strip continuing towards median emargination of posterior margin. Posterolateral lobes and sides of head posterior of eye-level smooth and shiny, on most hexagonally microsculptured. Scape pilosity appressed. Pronotum anteriorly weakly to superficially and transversely rugulose-punctate and posteriorly smooth, or in some specimens with superficial punctures and/or with weak to superficial rugulae. Humeri with weak and subangulate lateral process, pronotal declivity rounded to subangulate. Mesonotal process almost rightangled, second mesonotal process inconspicuous, at most represented as weak, quasi-vertical ridge. Metanotal groove forming broad constriction between mesonotum and propodeum in dorsal view, shallow to unimpressed in profile. Meso- and metapleuron weakly to superficially punctate, with several smooth spots (extent of sculpture strongly varies with viewing-angle). In profile, dorsopropodeum anterior to propodeal spines shorter than horizontal width of base of spine, in dorsal view anteromedially smooth, lateraloventrally densely punctate, posteriorly between spines transversely and weakly rugulose. Posteropropodeum weakly and transversely rugose-punctate, laterally with vertical curved rugae from spines towards metapleural carina(e). Metatibial pilosity appressed. Anterior face of petiole broadly smooth and shiny, rest of petiole and postpetiole densely punctate. Postpetiole with short irregular rugulae posterodorsally and conspicuous lobate flange posterolaterally. Gaster weakly punctate. Long standing hairs acute, present everywhere, except on propodeum. Mesonotum with shorter subdecumbent hairs and sometimes mesosoma completely without hairs other than short appressed pubescence.

Discussion: Pheidole rebeccae specimens were collected in the Ivory Coast and in Ghana. The minor workers from Ghana differ slightly from those from the Ivory Coast in the extent of sculpture on the first gastral tergite. Minor workers of P. rebeccae , in overall habitus and reduced body sculpture, are closest to those of P. glabrella , and best differentiated from the latter by wider head shape (CI: 94–98 [ rebeccae ] versus CI: 88–95 [ glabrella ]), shorter scapes, propodeal spines and metafemur (SI: 114–121, PSLI: 25–30, FI: 133–139 versus SI: 123–141, PSLI: 28–40, FI: 143–170), and more abundant standing hairs. Major workers of P. rebeccae are distinctively separated from those of other species by the short and weak longitudinal rugulae in face, largely smooth and shiny surfaces on the posterior half of face and pronotum, and reduced sculpture on meso- and metapleuron. Major workers of P. d a r w i n i also feature a reduced punctate sculpture in face and on posterior pronotum and partly smooth posterolateral lobes, but the longitudinal rugae are longer and more conspicuous, the punctures between the rugae are stronger, smooth surfaces on the head and mesosoma are restricted to significantly smaller areas and promesonotal standing hairs are long and erect versus shorter and decumbent in P. rebeccae . A unique character in P. darwini is the small number of erect hairs in combination with the appressed to decumbent pilosity along the outer edge of the scape, that is absent in the majors of P. rebeccae .

Etymology: This species is named after the first author’s daughter Rebecca.

Additional material examined: GHANA: (3 minor workers) Atewa Forest Reserve, nr. Kibi, 26.ii.1992 (R. Belshaw).

Figures

FIGURE 57 – 62 P. rebeccae sp. n.: full-face, lateral & dorsal view of minor (Fig. 57 – 59) (Ivory Coast, CASENT 0227955) and major worker (Fig. 60 – 62) (Ivory Coast, CASENT 0227954).