Pheidole heliosa Fischer, Hita Garcia & Peters

Type location Ivory Coast (Fischer, Hita Garcia & Peters, 2012: 12, Figures 42-47; major and minor workers); vic. Abidjan, 1976, no. 10 (T. Diomande) (BMNH: CASENT0227945). Paratypes: (8 minor workers) same data as holotype (BMNH: CASENT0227946, CASENT0227947, CASENT0227948, CASENT0227949) - no images on Antweb (November 2014)..

Diagnosis: Pheidole heliosa is the largest species in the P. pulchella group, with a long alitrunk and a wide pronotum. Color orange, major worker darker. Minor workers: head shape elongated, 1.25 times longer than wide. Occipital carina strongly developed and relatively broad. Scapes, legs and mandibles longest within the group, scape pilosity subdecumbent to suberect. Highest number of standing hairs on head and mesonotum within the group, also with laterally projecting hairs on meso- and metapleuron. Second metanotal process long and pronounced, postpetiole spheroidal in lateral view. Major worker: antennal scrobe absent, head margin with laterally projecting hairs. Promesonotal dome lower and longer than in other species of this group, in lateral view almost continuous with mesonotal processes. Propodeal spines straight, not curved posteriorly. Standing hairs abundant everywhere, including on dorsopropodeum and laterally on meso- and metapleuron.

Description of minor worker: Measurements (n=8): HL 1.056–1.089 (1.074), HW 0.778–0.822 (0.798), SL 1.302–1.429 (1.353), MDL 0.639–0.800 (0.685), EL 0.167–0.200 (0.176), MFL 1.600–1.740 (1.678), MTL 1.381–1.476 (1.427), WL 1.600–1.740 (1.678), PSL 0.294–0.400 (0.324), PTH 0.189–0.211 (0.198), PPH 0.233–0.278 (0.249), PTL 0.367–0.422 (0.385), PPL 0.267–0.283 (0.276), PTW 0.122–0.133 (0.128), PPW 0.261–0.300 (0.273), PW 0.567–0.611 (0.594); CI 73–76 (74), SI 162–174 (170), MDI 79–99 (86), PSLI 28–37 (30), PWI 73–76 (74), FI 206–213 (210), PpWI 200–232 (214), PpLI 129–152 (140).
Head about 1.25 times longer than wide, longest within group (CI 73–76), sides of head posterior of eye level elongated and converging evenly towards posterior margin. Occipital carina conspicuous and broad, almost collar-like. Mandibles very long (MDI 79–99), with strong rugulae laterally, grading to smooth masticatory margin. Clypeus smooth with short to inconspicuous lateral carinae. Face smooth, hexagonally microsculptured, malar carinae interrupted, ending posterior of eye level. Frontal carina developed but weak, ending at eye-level, space near antennal insertion surrounded by conspicuous carina. Scape long, longest within group (SI 162–174), in full face view and when laid back, surpassing posterior margin by more than one quarter to one third of its length, with subdecumbent to suberect pilosity, about twice as long as scape diameter. Pronotum wide (PWI 73–76), outline in lateral view elongate convex, rounded towards posterior declivity, smooth, only neck weakly punctured. Humeral area laterally with short superficial carina, in dorsal view posterior of highest point of pronotum lacking lateral pro- cess. Mesonotal processes conspicuous and well-developed, second process almost as long as first. Both processes, mesopleuron and propodeum weakly punctate. Metanotal groove relatively narrow, conspicuously impressed, dorsopropodeum with highest point immediately at metanotal groove, weakly declining towards base of spines. Propodeal spines moderately long (PSLI 28–37), metafemur very long (FI 206–213), and metatibial pilosity on inner edge subdecumbent, outer edge with longer suberect to subdecumbent hairs. Petiole and postpetiole smooth dorsally, weakly to superficially punctate ventrally. Postpetiole in lateral view spheroidal and widest within pulchella group (PpWI 200–232). Gaster smooth, hexagonally micropunctate. Standing hairs very abundant, slender and acute, of varying lengths, on mesonotum, propodeum and waist segments relatively short, on mesosoma not restricted to dorsal surfaces, also abundant lateroventrally (best visible in oblique dorsolateral view). Colour yellow to light orange.

Description of major worker: Measurements (holotype): HL 2.450, HW 2.350, SL 1.238, MDL 1.300, EL 0.267, MFL 1.980, MTL 1.640, WL 2.100, PSL 0.272, PTH 0.422, PPH 0.544, PTL 0.611, PPL 0.422, PTW 0.311, PPW 0.700, PW 1.067; CI 96, SI 53, MDI 55, PSLI 11, PWI 45, FI 84, PeI 29, PpI 66, PpWI 225, PpLI 145.
Head longer than wide (CI 96), mostly rugose-punctate, with short appressed to decumbent pubescence and in frontal view with several laterally projecting hairs. Median ocellus developed, small. Mandible relatively long (MDI 55). Median part of clypeus smooth, with conspicuous median and several weak submedian carinae. Frons longitudinally rugose-punctate, spaces in between weakly punctate, rugae reaching posterior margin only at median emargination, grading from weak to superficial rugulae on posterolateral lobes. Sides of head laterally of frons rugose-reticulate, punctate, in full-face view with several standing hairs projecting beyond lateral margin. Frontal carinae inconspicuous and short, antennal scrobe absent to inconspicuous. Promesonotum, in lateral view elongated and medially raised, dorsally, antero- and dorsolaterally rugose-reticulate, mediodorsally and posterolaterally mostly smooth with few short rugae present. Humeri weakly vertically processed, sharply marginate and rugose-reticulate. Mesonotal process uniquely shaped, broadly and squarely raised above shallowly declining mesonotal declivity, marginate and partly punctate, partly rugose-reticulate, and falling steeply to a shallow, but extensively produced, medially flexed, and posteriorly marginate second mesonotal process. Metanotal groove very narrowly impressed in lateral view. Meso- and metapleuron weakly punctate, with several weak to superficial irregular rugulae, metapleural carinae very conspicuous, flange-like produced laterally. In lateral view dorsopropodeum anterior to propodeal spines almost level and about as long as spines, weakly punctate, laterodorsally very densely punctate. Propodeal spines relatively short (PSLI 11), facing almost straight up, not curved posteriorly. Posteropropodeum punctate, partly overlain by superficial rugulae. Petiole laterodorsally and ventrally densely punctate, smooth dorsal area on peduncle laterally marginate. Postpetiole relatively wide compared to pronotal width (PpI: 66) and with strong ventral process, densely punctate, anterodorsally with short longitudinal, on highest point with interrupted longer transversal rugulae. First gastral tergite densely shagreened. Whole body with abundant, long, slender filiform standing hairs of varying lengths. Lateroventrally on pronotum and laterodorsally on propodeum with abundant suberect hairs, best visible in dorsal view. Scape with relatively short decumbent pilosity, metafemur with longer subdecumbent pilosity. Colour of antennae, mesosoma, metasoma and occipital corners reddish orange, rest of head darker.

Discussion: The species most similar to Pheidole heliosa are P. christinae and P. pulchella, especially in color (yellow to orange). All of them share the laterally projecting hairs on the head margin anterior and posterior of eyelevel, which separates them from the group of darkly colored species with laterally projecting hairs only posterior of eye-level or completely without. Minor workers of P. christinae and P. pulchella differ from P. heliosa in shape of the promesonotum, in lateral and dorsal view (PWI 64–70 and 64–68 versus PWI 73–76), especially in the development of the second mesonotal process, which in dorsal view is short and narrow [christinae] or inconspicuous [pulchella] versus long and broad [heliosa]. Pheidole pulchella differs from the other two orange coloured species in scape and metafemur pilosity, which is short and decumbent [pulchella] versus longer and subdecumbent to erect [christinae and heliosa]. The P. heliosa type series was collected in the Ivory Coast, additional minor workers were from Cameroon and were found in sifted leaf-litter.
Additional material examined: CAMEROON: (1 minor worker) Prov. Sud Ouest, Korup NP, 6.9 km 417° NW Mundemba, 19.iv.2000, 110 m, 05° 1.0' N, 8° 51.8' E (B.L. Fisher).

Illustration from Fischer, Hita Garcia & Peters (2012).