Pheidole darwini

Pheidole darwini occurs in Cameroon, Central African Republic and Gabon. The specimens have been collected from sifted leaf-litter and rotten logs.

Identification
A member of the pulchella species group.

Pheidole darwini, Pheidole batrachorum, and Pheidole setosa are the only darkly colored species with minor workers possessing several laterally projecting hairs on the head margin posterior of the eye-level. Pheidole darwini can be distinguished from P. batrachorum by the following characters: lack of [darwini] versus presence of [batrachorum] conspicuously impressed punctures on frons and vertex, wider head, shorter scapes, and longer spines (CI: 84–89, SI: 139–160, PSLI: 29–35 [darwini] versus CI: 79–86, SI: 153–172, PSLI: 21–29 [batrachorum]). From minor workers of P. setosa it is separated by: significantly narrower head margin, mostly decumbent to subdecumbent scape pilosity versus decumbent pilosity with additional erect to suberect hairs along outer edge, metatibia pilosity with subdecumbent hairs along outer edge versus uniform pilosity without subdecumbent hairs, and metafemur marginally longer (FI: 169–189 versus 167–168). The major workers are unique in their combination of diagnostic characters, in particular by the three to five erect hairs along the outer edge of the scape. (Fischer, Hita Garcia, & Peters 2012)

Distribution
Known from Cameroon, Central African Republic and Gabon.

Distribution based on Regional Taxon Lists
Afrotropical Region: Gabon.

Nomenclature

 *  darwini. Pheidole darwini Fischer, Hita Garcia & Peters, 2012: 19, figs. 21-26 (s.w.) GABON.

Color medium to dark brown, appendages slightly lighter. Minor worker: head shape elliptical (CI: 84–89), posterior of eye-level with laterally projecting hairs. Posterior head margin relatively narrow, vertex smooth. Scapes moderately long (SI: 139–160) with suberect pilosity. Dorsopronotum punctate anteriorly, partly overlain with irregular rugulae, posteriorly smooth. Spines relatively long (PSLI: 29–35), metatibia pilosity subdecumbent. Major worker: head sculpture weakly rugose-punctate, with moderately long rugae. Posterolateral lobes smooth and shiny, scape with appressed to decumbent pilosity plus a few erect hairs along outer edge. Dorsopropodeal sculpture weakly and irregularly transversely rugulose-punctate. In profile, dorsopropodeum anterior to propodeal spines shorter than or subequal to horizontal width of base of spine. Standing hairs long and thick, present everywhere except propodeum. Metatibia pilosity appressed to decumbent with additional subdecumbent to suberect hairs along outer edge.

Worker
Minor: Measurements (n=17): HL: 0.772–0.878 (0.838), HW: 0.667–0–756 (0.721), SL: 0.989–1.206 (1.076), MDL: 0.522–0.611 (0.562), EL: 0.161–0.189 (0.171), MFL: 1.133–1.381 (1.277), MTL: 0.878–1.067 (0.981), WL: 1.078–1.254 (1.163), PSL: 0.244–0.300 (0.271), PTH: 0.167–0.189 (0.179), PPH: 0.189–0.222 (0.210), PTL: 0.300–0.356 (0.332), PPL: 0.189–0.244 (0.220), PTW: 0.106–0.128 (0.118), PPW: 0 211–0.256 (0.225), PW: 0.444–0.511 (0.484); CI: 84–89 (86), SI: 139–160 (149), MDI: 75–82 (78), PSLI: 29–35 (32), PWI: 66–68 (67), FI: 169–189 (177), PpWI: 165–211 (191), PpLI: 135–176 (151).

Head elliptical, longer than wide (CI: 84–89), with sides of head rounded towards relatively narrow posterior margin and head margin posterior of eye-level in full-face view with laterally projecting hairs. Occipital carina conspicuous, medially with a weak concavity in full-face view. Dorsum of head smooth and shiny, hexagonally micropunctate to very faintly punctuate. Malar space with few short carinae next to antennal insertion ending at posterior eye-level. Scapes moderately long (SI: 139–160), pilosity basally subdecumbent to decumbent, apically subdecumbent to suberect. Dorsopronotum in lateral view flat, anteriorly towards neck weakly punctate, partly overlain by some weak irregular rugulae, posteriorly grading to smooth and relatively steep posterior declivity. Lateropronotum partly to completely smooth and shiny. Both metanotal processes conspicuous and well-developed, sharply angulate, metanotal groove deep and broad. Mesopleuron and propodeum uniformly punctuate, dorsopropodeum in lateral view level to declining gently towards base of spines. Propodeal spines moderately long (PSLI: 29–35). Petiole and postpetiole punctate, dorsally superficially and partly smooth. Gaster smooth and shiny, anteriorly with superficially punctate central area, in size not larger than dorsal surface of postpetiole. Pilosity generally abundant with long erect setae and shorter suberect to subdecumbent hairs present. Metatibia with appressed to decumbent pilosity on inner edge, subdecumbent on outer edge. Color medium to dark brown.

Major: Measurements (holotype): HL: 1.960, HW: 1.960, SL: 1.044, MDL: 1.000, EL: 0.239, MFL: 1.571, MTL: 1.190, WL: 1.476, PSL: 0.356, PTH: 0.322, PPH: 0.400, PTL: 0.556, PPL: 0.356, PTW: 0.222, PPW: 0.500, PW: 0.878; CI: 100, SI: 53, MDI: 51, PSLI: 18, PWI: 45, FI: 80, PeI: 25, PpI: 57, PpWI: 225, PpLI: 156.

Measurements (n=9): HL: 1.980–2.200 (2.099), HW: 1.960–2.225 (2.120), SL: 1.011–1.133 (1.056), MDL: 0.944–1.056 (1.011), EL: 0.239–0.267 (0.251), MFL: 1.556–1.714 (1.623), MTL: 1.206–1.667 (1.293), WL: 1.492–1.651 (1.570), PSL: 0.333–0.389 (0.354), PTH: 0.322–0.378 (0.341), PPH: 0.367–0.467 (0.422), PTL: 0.544–0.667 (0.590), PPL: 0.333–0.389 (0.360), PTW: 0.211–0.267 (0.236), PPW: 0.467–0.589 (0.546), PW: 0.856–0.978 (0.931); CI: 99–104 (101), SI: 49–53 (50), MDI: 42–51 (48), PSLI: 16–18 (17), PWI: 43–45 (44), FI: 75–80 (77), PeI: 24–27 (25), PpI: 55–63 (59), PpWI: 219–252 (231), PpLI: 151–176 (164).

Frons and sides of head weakly to superficially rugose-punctate, grading weaker on anterior posterolateral lobes, posteriorly smooth and shiny, median excavation with a narrow superficially sculptured strip. Laterally and in profile view smooth area extending anteriorly, almost towards eye-level. Pilosity on scape basally appressed, apically decumbent, in addition with three to five erect hairs, distributed along outer edge. Promesonotal outline slightly rounded, mesonotal process subangulate, with relatively steep posterior declivity. Second process inconspicuous, weakly raised carina or narrow ridge present instead. Pronotum transversely to irregularly rugulose-punctate, posterodorsally less rugulose, punctures either slightly weaker or superficial, posterolaterally smooth and shiny or superficially punctate-rugose. Humeral area slightly processed to subangulate laterally, promesonotal declivity smooth, with hexagonal microsculpture. Meso- and metapleuron punctate, dorsopropodeum weakly punctate. In profile, dorsopropodeum anterior to propodeal spines shorter than horizontal width of base of spine. Area between spines and posteropropodeum punctate or weakly punctate, overlain by weak or superficial transverse rugulae, also posterolateral rugae towards metapleural carinae present. Petiole and postpetiole densely punctate, except smooth anterodorsal petiole. Postpetiolar ventral process significantly anteriorly produced. Punctures on anterior half of first gastral tergite grading to hexagonal microsculpture on second half. Long standing, often truncated, hairs relatively abundant on dorsal body, but absent from propodeum. Metatibia with appressed to decumbent pilosity and with subdecumbent to suberect hairs along outer edge. Color brown to dark brown, appendages lighter.

Type Material
Holotype: (major worker) GABON, Prov. Woleu-Ntem, 31.3 km 108° ESE Minvoul, 02° 04.8' N, 12° 24.4' E, 600 m, 7.ii.1998 (B.L. Fisher) (: CASENT0218307). Paratypes: (8 major workers) same data as holotype : CASENT0218300, CASC: CASENT0218303, CASENT0218304, CASENT0218306, CASENT0218308, : CASENT0218301, : CASENT0218302); (12 minor workers) Prov. Woleu-Ntem, 31.3 km 108° ESE Minvoul, 02° 04.8' N, 12° 24.4' E, 600 m, 11.ii.1998 (B.L. Fisher) (BMNH: CASENT0218313, CASENT0218315, CASC: CASENT0218311, CASENT0218317, CASENT0218318, MHNG: CASENT0218316, SAMC: CASENT0218319); (18 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) (CASC: CASENT0218324, CASENT0218325, CASENT0218326, CASENT0218327, CASENT0218328).

References based on Global Ant Biodiversity Informatics

 * Fischer, G., F. Hita García, and M. K. Peters. "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 (2012): 1-43.