Pheidole semidea, 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 : 38-40

Pheidole semidea sp. n.

( Figures 63–68 )

Holotype: (major worker) NIGERIA, Gambari , 22.vii.69, in log (B. Bolton) ( BMNH: CASENT0227959 ). Paratypes: (2 major workers, 5 minor workers) same data as holotype ( BMNH: CASENT0227960, CASENT0227961).

Diagnosis: Color light to dark brown. Minor workers: head shape rounded (CI: 85–89), with medially impressed occipital carina. Dorsal surfaces of head, promesonotum and metasoma smooth, at most superficially punctate. Second mesonotal process in lateral view distinctly raised above level of anterior dorsopropodeum. Petiole relatively short (PpLI: 126–144). Major workers: frons with moderately long rugae, vertex weakly rugose-reticulate, and posterolateral lobes with oblique rugulae. Mesonotal process in lateral view almost right-angled, second process very shallow and raised above level of dorsopropodeum. In profile, dorsopropodeum anterior to propodeal spines longer than horizontal width of base of spine. Postpetiole moderately wide (PWI: 192–221) and standing hairs on pronotum medially inclined.

Description of minor worker: Measurements (n=5): HL: 0.778–.0811 (0.796), HW: 0.689–0.722 (0.697), SL: 0.967–1.033 (0.989), MDL: 0.533–0.544 (0.542), EL: 0.156–0.189 (0.169), MFL: 1.111–1.190 (1.149), MTL: 0.900–0.911 (0.904), WL: 1.044–1.111 (1.084), PSL: 0.206–0.233 (0.222), PTH: 0.167–0.172 (0.168), PPH: 0.178–0.200 (0.192), PTL: 0.256–0.289 (0.276), PPL: 0.189–0.222 (0.207), PTW: 0.111–0.122 (0.114), PPW: 0.200–0.222 (0.211), PW: 0.467–0.478 (0.475); CI: 85–89 (88), SI: 134–150 (142), MDI: 75–79 (78), PSLI: 26–29 (28), PWI: 68–69 (69), FI: 160–173 (165), PpWI: 173–200 (185), PpLI: 126–144 (134).

Head shape in full-face view slightly elliptical with roundly convex posterior margin (CI: 85–89). Occipital carina conspicuous and medially impressed. Clypeus smooth, lateral carinae weak. Face smooth, except hexagonal microsculpture, superficially punctate laterally towards eyes. Malar rugulae well-developed, disappearing posterior of eyes. Scape surpassing posterior margin by about one third of its length (SI: 134–150), with decumbent pilosity, apically some hairs subdecumbent. Promesonotum in lateral view flat, subangular, anterodorsally towards neck weakly punctate, rest smooth. First mesonotal process obtusely angulate, dorsally smooth. Second process conspicuous and distinctly raised above level of dorsopropodeum. Metanotal groove asymmetrically impressed, posteriorly more shallowly. Mesopleuron and propodeum punctate, with superficially sculptured spots on katepisternum and posterior dorsopropodeum. Spines moderately long (PSLI: 26–35), posteriorly strongly curved. Metafemur long (FI: 158–173), metatibial pilosity decumbent. Petiole punctate laterally and ventrally, dorsolateral postpetiole and ventral process weakly punctate, dorsum of both waist segments smooth, partly micropunctate. Gaster smooth, anteriorly near insertion of postpetiole superficially punctate. Standing hairs on head, postpetiole and gaster long and acute, on petiole short and on promesonotum mostly moderately long and subdecumbent, directed towards center or dorsopronotum. Body surface also with several short and relatively long appressed hairs. Color light to dark brown, gaster darker, mandibles partly transparent.

Description of major worker: Measurements (holotype): HL: 1.800, HW: 1.760, SL: 0.978, MDL: 0.833, EL: 0.222, MFL: 1.444, MTL: 1.078, WL: 1.429, PSL: 0.300, PTH: 0.333, PPH: 0.367, PTL: 0.500, PPL: 0.311, PTW: 0.222, PPW: 0.467, PW: 0.800; CI: 98, SI: 56, MDI: 47, PSLI: 17, PWI: 45, FI: 82, PeI: 28, PpI: 58, PpWI: 210, PpLI: 161.

Measurements (n=3): HL: 1.619–1.860 (1.705), HW: 1.635–1.820 (1.724), SL: 0.922–1.000 (0.975), MDL: 0.722–0.833 (0.792), EL: 0.211–0.222 (0.215), MFL: 1.349–1.444 (1.393), MTL: 1.000–1.111 (1.061), WL: 1.286–1.476 (1.365), PSL: 0.244–0.306 (0.285), PTH: 0.250–0.311 (0.285), PPH: 0.311–0.406 (0.357), PTL: 0.489–0.556 (0.515), PPL: 0.333–0.344 (0.336), PTW: 0.200–0.233 (0.211), PPW: 0.383–0.500 (0.447), PW: 0.711–0.800 (0.764); CI: 98–106 (101), SI: 55–58 (57), MDI: 43–48 (46), PSLI: 15–18 (16), PWI: 39–47 (44), FI: 79–83 (81), PeI: 25–30 (28), PpI: 50–66 (579, PpWI: 192–221 (212), PpLI: 147–161(153).

Face entirely rugose-punctate, rugae relatively long and sometimes interrupted on frons, posteriorly with some weak cross-meshes, disappearing towards obliquely and weakly rugulose-punctate posterolateral lobes. Outer corners of posterolateral lobes and spaces between rugae on frons superficially punctate, laterally of antennal scrobe irregularly rugose-reticulate. Scape with decumbent pilosity. Promesonotum in lateral view short, posteriorly subangulate, declivity short, anterodorsally and anterolaterally weakly and irregularly rugulose-punctate, grading to superficially punctate posteriorly on dorsopronotum, lateropronotum and mesonotum. First mesonotal process right-angled, with a steep declivity. Second process small or reduced to short, narrowly raised carina, but raised above level of dorsopropodeum. Meso- and metapleuron punctate, with smooth area on katepisternum and posteroventral metapleuron. Metapleural carina relatively short and weak, gland scrobe weak to inconspicuous. Dorsal and posterior propodeum smooth to superficially punctate, with transverse rugula(e) between spines and moderately developed, longitudinal rugula(e) posteriorly along spines. Petiole and postpetiole punctate, except medial area of anterodorsal petiole. First gastral tergite shagreened, posteriorly slightly weaker. Metatibia with appressed pilosity. Acute, long standing hairs present on head, postpetiole, dorsal gaster and pronotum, on the latter medially inclined. Color reddish brown, gaster darker.

Discussion: Pheidole semidea , in morphometrics and overall habitus, is closest to P. d e a, but differentiated from the latter by the following characters: sculpture of minor workers in face strongly reduced to mostly smooth and shiny versus weakly to superficially punctate in P. d e a, second mesonotal process higher situated and raised above dorsopropodeal outline, spines more strongly curved, petiole shorter and postpetiole longer (PpLI: 126–144 versus PpLI: 156–223). Rugae on frons and vertex of major workers moderately long, posterolateral lobes with oblique rugulae versus very long, longitudinal and subparallel rugae from frons to head margin in P. d e a, postpetiole on average wider (PpWI: 192–221) in P. s e m i d e a versus relatively narrow (PpWI: 177–210) in P. d e a, and first gastral tergite almost completely shagreened versus only anteriorly shagreened in P. d e a. Given the relatively minor differences between minor workers of the two species, it is possible that they are conspecifics and that intermediate forms exist within or between the West and East African populations. Yet, we propose that P. semidea and P. d e a should be considered separate species until additional data from future sampling proves otherwise. The P. s e m i d e a types were collected from a log at Gambari, Nigeria, and another major was collected from Ibadan, Nigeria.

Additional material examined: NIGERIA: (1 major worker) Ibadan, IITA (= International Institute of Tropical Agriculture), 18.v.81, no. 16 (A. Russel-Smith) .

Figures

FIGURE 63 – 68 P. s e m i d e a sp. n.: full-face, lateral & dorsal view of minor (Fig. 63 – 65) (Nigeria, CASENT 0227960) and major worker (Fig. 66 – 68) (Nigeria, CASENT 0227960).