Pheidole pulchella, Santschi. Comparison, 1910

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 : 7-8

P. pulchella group:

Relatively large species (minor worker HW: 0.66–0.97 mm (n=154), major worker HW: 1.63–2.35 (n=53)), with relatively long spines in both, minor (PSLI: 21–40) and major workers (PSLI: 11–19), which are usually curved backwards, except in P. diomandei . Minors always with a distinct promesonotal process, followed by a well-developed or conspicuous smaller process ( Fig. 1 B–4) and a distinctly impressed metanotal groove. Majors always with a distinct promesonotal process and hypostomal margin of the head always with two conspicuous inner and two outer submedian teeth, but lacking the median process.

Both worker subcastes with a well-developed postpetiolar ventral process, similar to the species of the megacephala complex, but distinctly separated from them by the previous character combination.

Minor workers: head shape in full-face view variable among species, but never square with angulate posterolateral corners, from short and rounded (CI: 85–98) with sides of head strongly convex, posterior margin convex [ dea ], or almost straight [ rebeccae ], to long-elliptical (CI: 73–84), sub-angular at eye-level and posteriorly elongate towards occipital carina ( Fig. 1 B–2) [ christinae , heliosa ]. Mandibles smooth and shiny, sometimes with very superficial rugulae, laterally with weak longitudinal rugulae. Eyes situated near midlength of the head, of medium size (EI: 19–29). Scapes moderately to very long (SI: 102–174) and surpassing posterior head margin by one quarter to approximately one third of their length. Occipital carina always conspicuous in full-face view. Mesonotal declivity interrupted by promesonotal process, followed by a smaller process between promesonotal process and metanotal groove. The second, smaller, process is reduced and less conspicuous in some species. Propodeal spines long and spinose, much longer than distance between their bases (PSLI: 21–40), curved posteriorly towards petiole, rarely straight. Promesonotum, in lateral view, with angulate to subangulate edges, pronotal dorsum flat to weakly rounded, never strongly convex. Petiole longer than postpetiole (PpLI: 117–223), and in dorsal view usually about half as wide (PpWI: 152–232). Postpetiole also with well-developed convex ventral process and about as high as long, with subglobular to globular shape in profile. In dorsal view postpetiole about as long as wide, with a roughly trapezoidal shape. Pilosity with few to many long acute standing hairs, some species with hair apices truncate (or bifurcate), but in some species almost completely absent from dorsum of head, meso- and metasoma. Mesonotum and propodeum often with shorter, suberect to subdecumbent hairs. Standing hairs never very short and stiff. Between long erect hairs on head often shorter suberect to subdecumbent hairs present. Sculpture variable between species, with relatively little intraspecific variation, from completely and strongly punctate [ nimba ] to mostly smooth and shiny [ rebeccae ], but mesonotum and propodeum never completely smooth and shiny, at least partly punctate.

Major workers: head about as wide as long (CI: 96–105), broadest always between eye level and occipital margin, frons and sides of head rugose-punctate to varying degrees. Posterolateral lobes often differently sculptured. Dorsal surface of mandible smooth, laterally longitudinally rugulose. Clypeus with median longitudinal carina present. Scapes moderately long (SI: 49–58). Hypostomal margin always with two inner and two outer submedian teeth present, median process absent to inconspicuous. In full-face view, and for all species but P. heliosa , head margin without projecting hairs of any kind, only with relatively short appressed pilosity and long erect hairs, that are visible in lateral view. Pilosity on scape appressed to subdecumbent. Humeral area laterally not or weakly produced, mesonotal process always developed and with posterior steep declivity towards metanotal groove, which, in lateral view, is barely to broadly impressed. Propodeal spines relatively long and spinose, longer than distance between their bases. Petiole longer than postpetiole (PpLI: 131–176). Postpetiole considerably wider than petiole (PpWI: 177–252), wider and higher than long, in lateral view with anteriorly produced ventral process. Pilosity and sculpture similar to minor workers.

Comments on the P. pulchella group:

The Pheidole pulchella species group was defined in the process of our identification efforts of two very distinct groups of specimens from the Kakamega Forest in Western Kenya and from the Budongo and Rabongo Forests in Uganda. Both were at first identified as P. pulchella Santschi. Comparison with type material later revealed the dark colored morphospecies to be conspecific with P. d e a Santschi from the Democratic Republic of Congo. We are now able to describe the previously unknown major workers. The orange colored specimens from Budongo Forest belong to a previously undescribed species and are likely to be closely related to P. pulchella Santschi. In subsequent type material examinations and museum visits, additional undescribed material was found from the Ivory Coast in the West, along the equatorial rainforest belt to Gabon, Central African Republic, towards Kenya and Tanzania in the East. In their general morphology the species in this group are well separated from those of other groups (see group definition above, first paragraph).

Most of the collection localities for species of the P. pulchella group are in rainforests; habitats of a few are not indicated on the labels. Specimens were caught in pitfall-traps, leaf-litter extractions, by beating of the lower vegetation, or by hand-collection. Thus, the species in this group are most likely forest specialists living and/or foraging on the ground and in the lower vegetation. Their conspicuous morphology with the relatively large size, long spines and appendages, and well-developed eyes indicates that these species are not living within, but rather upon or above the leaf-litter layer. They possibly nest in dead wood, because several of the specimens, especially the more rarely observed majors, were collected from rotten logs. Still, the biology of this species group is largely unknown and there are no records or observations available, other than the collection data mentioned on the labels.

Figures

FIGURE 1 A) Pheidole pulchella, full-face view of minor worker: the two lines show the lateral clypeal carinae on the sides of the clypeus (1). B) P. pulchella, lateral view of minor worker: illustrating posterior head margin with a weakly developed occipital carina (2), promesonotum with inconspicuous humeri (3), and second mesonotal process not reduced (4). C) P. pulchella, lateral view of major worker: illustrating second mesonotal process reduced to a small ridge anterior of the metanotal groove (5) and well-developed metapleural carina (6) situated above the metapleural gland scrobe (7). D) P. pulchella, in oblique fronto-dorsal (dorsocaudad) view (Will Ericson 2011): measurement of propodeal spine length (PSL), the bold line representing the measurement, bordered by the perpendicular line across the base of the spine.