Pheidole dea Santschi

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 : 22-25

Pheidole dea Santschi

( Figures 27–35 )

Pheidole dea Santschi, 1921: 115 . Lectotype (minor worker) [here designated]: D.R. CONGO, Lugombe ( Gérard ) ( NHMB) [examined] .

Diagnosis: Color brown to dark blackish brown. Minor workers: head shape broadly rounded (CI: 86–93), posterior head margin evenly rounded to weakly compressed. Central area between eyes and posterior pronotum smooth and shiny to superficially punctate or hexagonally microsculptured. Scape and metafemur moderately long (SI: 134–147, FI: 158–174), pilosity decumbent to subdecumbent. Mesopleuron and propodeum uniformly punctuate, edge of first mesonotal process in lateral view rounded. Second process not higher than level of dorsopropodeum, metanotal groove narrow. Postpetiole relatively narrowly developed and short (PpLI: 155–223). Standing hairs almost completely absent from mesosoma, but at least few scattered hairs on head and metasoma. Major workers: rugae in face very strong, almost parallel, some continuing uninterrupted towards posterior head margin. Mesonotal process in lateral view obtuse. Second process conspicuous to reduced, not raised higher than level of dorsopropodeum. In profile, dorsopropodeum anterior to propodeal spines longer than horizontal width of base of spine. Postpetiole relatively narrow, on average less than twice as wide as petiole (PpWI: 177–210). Standing hairs on pronotum mostly absent.

Description of minor worker: Measurements (lectotype): HL: 0.856, HW: 0.944, SL: 1.156, MDL: 0.667, EL: 0.200, MFL: 1.444, MTL: 1.100, WL: 1.333, PSL: 0.278, PTH: 0.200, PPH: 0.244, PTL: 0.367, PPL: 0.222, PTW: 0.144, PPW: 0.244) PW: 0.567, CI: 91, SI: 135, MDI: 78, PSLI: 29, FI: 169, PWI: 66, FI: 169, PpWI: 169, PpLI: 165.

Measurements (n=32): HL: 0.733–0.922 (0.849), HW: 0.656–0.833 (0.759), SL: 0.944–1.144 (1.070), MDL: 0.500–0.611 (0.571), EL: 0.167–0.198 (0.179), MFL: 1.089–1.397 (1.262), MTL: 0.811–1.100 (0.968), WL: 1.011–1.317 (1.159), PSL: 0.200–0.278 (0.243), PTH: 0.156–0.200 (0.178), PPH: 0.156–0.222 (0.195), PTL: 0.256–0.367 (0.318), PPL: 0.144–0.200 (0.182), PTW: 0.106–0.135 (0.121), PPW: 0.167–0.233 (0.204), PW: 0.422–0.533 (0.487); CI: 86–93 (89), SI: 134–147 (141), MDI: 72–79 (75), PSLI: 25–32 (29), PWI: 61–67 (64), FI: 158–174 (166), PpWI: 152–191 (169), PpLI: 156–223 (175).

Head shape broadly rounded (CI: 86–93), convex sides evenly rounding into uncompressed or weakly compressed posterior margin. Occipital carina narrow, face distinctly to superficially punctate, medially at eye-level smooth, hexagonally microsculptured. Punctures laterally on malar area and near eyes slightly stronger, malar carinae long, often faintly continuing towards posterolateral head margin, ending between latter and eye-level. Scape moderately long, in full face view and when laid back, surpassing posterior head margin by about one third of its length (SI: 134–147), with decumbent to subdecumbent pilosity. Pronotal outline in lateral view slightly angulate, humeral area flat to faintly convex. First mesonotal process obtusely angulate to weakly flattened, subangulate and appearing worn. Second process small to almost inconspicuous, with angle at same level as anterior dorsopropodeum. Metanotal groove conspicuous, narrowly impressed, anteropronotum punctate or weakly punctuate. Dorsopronotum, lateropronotum and mesonotum mostly smooth, hexagonally microsculptured. Mesopleuron and propodeum punctuate, dorsopropodeum flatly declining to base of spines. Propodeal spines relatively short (PSLI: 25–32) and often weakly curved or almost straight. Metafemur moderately long (FI: 158–174), metatibia with decumbent pilosity. Petiole and postpetiole lateroventrally and posterodorsally weakly to superficially punctate, upper dorsum smooth. Gaster smooth and shiny, anteriorly with small shagreened to microsculptured spot. Standing hairs moderately long and scarce, sometimes missing on mesosoma, rarely completely absent from dorsal surfaces, except on end of first gastral tergite and posteriorly, also with few shorter subdecumbent hairs on waist segments. In every specimen except holotype, petiole and postpetiole in dorsal view with short, laterally projecting hairs present. Color medium to dark blackish brown.

Description of major worker (previously undescribed): Measurements (n=7): HL: 1.760–1.980 (1.867), HW: 1.780–1.980 (1.873), SL: 1.011–1.089 (1.046), MDL: 0.822–1.000 (0.888), EL: 0.222–0.244 (0.232), MFL: 1.460–1.603 (1.515), MTL: 1.111–1.254 (1.172), WL: 1.460–1.587 (1.519), PSL: 0.294–0.356 (0.326), PTH: 0.267–0.322 (0.307), PPH: 0.322–0.378 (0.347), PTL: 0.456–0.567 (0.507), PPL: 0.289–0.333 (0.309), PTW: 0.200–0.244 (0.222), PPW: 0.378–0.500 (0.431), PW: 0.800–0.878 (0.830); CI: 99–102 (100), SI: 54–57 (56), MDI: 42–51 (47), PSLI: 16–19 (17), PWI: 43–46 (44), FI: 79–83 (81), PeI: 25–29 (27), PpI: 46–58 (52), PpWI: 177–210 (194), PpLI: 155–176 (164).

Face rugose-punctate, with long, subparallel and uninterrupted rugae, continuing (more weakly) to posterolateral lobes. Punctures lateral of frons weak, grading to superficial on frons and corners of lobes. Scape pilosity decumbent. Promesonotal outline rounded dorsally, weakly subangulate posteriorly towards pronotal declivity. Anteropronotum irregularly and weakly rugose-punctate, grading to superficially sculptured or almost smooth on posteropronotum and pronotal declivity, posterior lateropronotum smooth and shiny. First mesonotal process strongly produced, obliquely angulate. Dorsal mesonotum partially to completely smooth, or faintly rugulose on posterior mesonotal process. Second mesonotal process in some specimens low and conspicuous, in others short and reduced to a weakly raised ridge. Metanotal groove narrow and conspicuously impressed. In profile, dorsopropodeum anterior to propodeal spines of equal length or slightly longer than horizontal width of base of spines, in dorsal view sometimes with smooth median area. Propodeal spines strongly and massively developed, posteropropodeum weakly to superficially transversely rugulose-punctate. Punctures on mesopleuron and metapleuron weak to superficial, posterior metapleuron ventrally of spiracle smooth. Metapleural gland scrobe and carinae weak. Metatibia pilosity relatively short, appressed to decumbent. Smooth median strip on anterodorsal petiole very narrow. Postpetiole usually relatively narrow (PpWI: 177–210), on average almost twice as wide as petiole, laterally weakly angulate to rounded, posterolateral flange narrow to inconspicuous, ventral process short and weakly developed. Gaster anteriorly, near articulation to postpetiole, weakly punctate or shagreened, rest smooth and shiny, hexagonally microsculptured. Long standing hairs present on head, postpetiole, and gaster, absent to almost absent on mesosoma, rarely with one pair present on posterolateral dorsopronotum, absent on petiole.

Discussion: Pheidole dea was described from two minor workers, one of which is destroyed except for the postpetiole and gaster. Unfortunately the postpetiole of the lectotype is also partly destroyed, thus the postpetiole measurements of the lectotype may be not as accurate as the other measurements. New material from three East African countries reveals distinct variation in head sculpture of the minor worker among the different localities. The P. d e a lectotype most closely resembles the minor workers from Tanzania. Both possess the same distinct punctures (excluding the smooth central area at eye-level) in the face on frons and vertex, in which they differ from the minor workers found in Kenya and Uganda, which have only weak to superficial sculpture on frons and vertex.

The P. d e a lectotype lacks conspicuous pilosity, other than short decumbent to subdecumbent pubescence, and a few long hairs on the third gastral tergite, but this could be due to abrasion of this old specimen. Although standing hairs in the new material of P. d e a can be strongly reduced, some hairs usually remain on the head or first gastral tergite. Additionally, the waist segments are endowed with some shorter, posteriorly and laterally projecting hairs, which are also absent in the lectotype. However, in a closer examination of the latter, the typical and faintly elevated punctures, where standing hairs are inserted, were found on head and mesosoma. This suggests the hairs were probably lost prior to or after its collection. Other significantly differentiating characters could not be observed. The species most similar to P. d e a is P. s e m i d e a. Minor workers of the latter possess a relatively broader and longer postpetiole (PpWI: 173–200 and PpLI: 126–167 [ semidea ] versus PpWI: 152–191 and PpLI: 156–223 [ dea ]). In P. semidea the second mesonotal process in lateral view is slightly raised above the level of the dorsopropodeum and usually up to three pairs of centrally inclined, moderately long hairs are found on the anterior, lateral and posterior corners of the promesonotal dorsum. The major workers of P. s e m i d e a possess an irregular pattern of longitudinal rugae on the frons, joined by a few cross-meshes on the vertex and oblique rugulose-punctate sculpture on the posterolateral lobes versus regular longitudinal rugae from frons to vertex in P. d e a. They also have a higher situated second mesonotal process and, on average, a slightly longer and wider postpetiole (PpLI: 154, PpWI: 211 versus PpLI: 164, PpWI: 194).

The new material of P. d e a has been collected in four forests in Eastern Africa: Kakamega Forest in Western Kenya, Rabongo Forest and Budongo Forest in Uganda, and Gombe in Tanzania. In Kakamega P. d e a is among the more rarely collected Pheidole species, only found in 26 out of 800 pitfall-traps, where it constituted 2.2 % of all Pheidole individuals collected (in winkler samples 0.2 %). Stable isotope measurements of several Kakamega specimens revealed that P. d e a had the highest d15N value among its congeners from the same location (unpublished). Its trophic position is in the third trophic level of the local food network, indicating that it is probably a more specialized predator than other Pheidole species. Details about its diet, however, remain unknown.

Additional material examined : KENYA: (4 major workers, 8 minor workers) Kakamega District: Isecheno Forest Reserve, 1600 m 8.ii.2002 (R.R. Snelling) ; (1 minor worker, 1 major worker) Kakamega Forest, Colobus, 00° 21' 4.9'' N, 34° 51' 41.1'' E, 12.vi.2007, 1650 m (M. Peters) ; (1 minor worker, 1 major worker) Kakamega Forest, Buyangu, 00° 20' 53.6" N, 34° 51' 54.1" E, 12.vii.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Isecheno B, 00° 14' 52.3'' N, 34° 52' 5.3'' E, vi.2008, 1650 m (F. H i t a G a rc i a) ; (1 minor worker) Kakamega Forest, Salazar, 00° 19' 36'' N, 34° 52' 14.6'' E, 21.vi.2007, 1650 m (S. Maurer) ; (1 minor worker) Kakamega Forest, Malawa East, 00° 27' 15.7" N, 34° 51' 48.8" E, 03.vii.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Yala, 00° 12' 9' 'N, 34° 52' 6' E, v.2008, 1650 m (M. Peters) ; (2 minor workers) Kakamega Forest, Udo´s camp, 00° 21’ 7.9'' N, 34° 52' 2.6'' E, 02.vii.2007, 1650 m (G. F i s c h e r) ; (2 minor workers) Kakamega Forest, Malava West, 00° 27' 0.9'' N, 34° 50' 52.9'' E, 03.vii.2007, 1650 m (G. F i s c h e r) ; (1 minor worker) Kakamega Forest, Kisere, 00° 23' 6.2'' N, 34° 53' 37.8'' E, 16.vii.2007, 1650 m (F. Hita Garcia) ; (1 minor worker) Kakamega Forest, Salazar, 00° 19' 36'' N, 34° 52' 14.6" E, 21.vi.2007, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Yala, 00° 12' 09.9" N, 34° 52' 52.6" E, 19.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Salazar, 00° 19' 36'' N, 34° 52' 14.6'' E, 09.iii.2009, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Colobus, 00° 21' 05" N, 34° 51' 41" E, vii.2009, 1650 m (G. F i s c h e r) ; (9 minor workers) Kakamega Forest, Malava East, 00° 27' 10.6'' N, 34° 51' 48.7'' E, 19.vi.2007, 1650 m (G. F i s c h e r) ; (1 minor worker) Kakamega Forest, Kisere, 00° 23' 07" N, 34° 53' 32.7" E, 24.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Malawa East, 00° 27' 13.8" N, 34° 51' 44.6" E, 26.vi.2002, 1650 m (M. Peters) ; (3 minor workers) Kakamega Forest, Yala, 00° 13' 15.5'' N, 34° 55' 52.3'' E, 23.viii.2007, 1650 m (F. Hita Garcia) ; (1 minor worker) Kakamega Forest, Colobus, 00° 21' 18.5'' N, 34° 51' 30.1'' E, 14.vi.2007, 1650 m (M. Peters) ; (1 minor worker) 00° 12' 58.5" N, 34° 55' 56.6" E, Kakamega Forest, Ikuywa, 20.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Ikuywa, 00° 13' 13.8" N, 34° 55' 52.1" E, 20.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, vi./ vii.2002, 1653 m (M. Peters) ; Kakamega Forest, (2 minor workers) Kisere, 00° 23' 6.2'' N, 34° 53' 37.8'' E, 16.vii.2007, 1650 m (F. Hita Garcia) ; (1 minor worker) Kakamega Forest, Ikuywa, 20.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Isecheno B, 00°15' 16.6" N, 34° 52' 06.1" E, 18.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Isecheno B, 00° 14' 52.3'' N, 34° 52' 5.3'' E, vi.2008, 1650 m (F. Hita Garcia) ; (1 minor worker) Kakamega Forest, Kisere, 00° 23' 07" N, 34° 53' 32.7" E, 17.vi.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Kisere, 00° 23' 07" N, 34° 53' 32.7" E, 01.vii.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Kisere, 00° 23' 03.1" N, 34° 53' 38.8" E, 24.vi.2002, 1650 m (M. Peters) ; (6 minor workers) Kakamega Forest, Malawa East, 00° 27' 20.2" N, 34° 51' 39.1" E, 26.vi.2002, 1650 m (M. Peters) ; (5 minor workers) Kakamega Forest, Malawa East, 00° 27' 20.2" N, 34° 51' 39.1" E, 03.vii.2002, 1650 m (M. Peters) ; (2 minor workers) Kakamega Forest, Malawa East, 00° 27' 13.8" N, 34° 51' 44.6" E, 03.vii.2002, 1650 m (M. Peters) ; (1 minor worker) Kakamega Forest, Malawa East, 00° 27' 15.7" N, 34° 51' 48.8" E, 19.vi.2002, 1650 m, (M. Peters) ; TANZANIA: (3 major workers, 16 minor workers) Gombe Stream N.P., 04° 42' S, 29° 37' E, 790 m, 11.i.2010 (R. O’Malley) ; UGANDA: (3 minor workers) Bunyoro District, Budongo Forest FS, 01° 43.583' N, 31° 33.142' E, 1081 m, 08.vii.09 (W. Freund & T. Klug) ; (2 minor workers) Murchinson Falls NP, Rabongo Forest, 02° 04.431' N, 31° 51.974' E, 958 m, 11.vii.09 (W. Freund & T. Klug) .

Figures

FIGURE 27 – 29 P. d e a Santschi lectotype: full-face, lateral & dorsal view of minor worker (Congo, CASENT 0227966).

FIGURE 30 – 35 P. d e a Santschi non-type: full-face, lateral & dorsal view of minor (Fig. 30 – 32) (Kenya, CASENT 0227964) and major worker (Fig. 33 – 35) (Kenya, CASENT 0227965).