Discothyrea poweri

Discothyrea poweri appears to be relatively widespread in South Africa, ranging from the Western and Northern Cape to KwaZulu-Natal. It was found in a variety of habitats at elevations ranging from just above sea level to about 1700 m, which were predominantly forests, but also bushland, coastal shrub or botanical gardens. It has been collected from leaf litter, rotten wood, and under stones.

Identification
Hita-Garcia and Lieberman (2019) - The following character combination distinguishes D. poweri from the remainder of the complex:
 * generally larger species (WL 0.67–0.84)
 * comparatively long antennal scapes (SI 61–68)
 * in dorsal view mesosoma very thin and elongate (DMI 45–52; DMI2 72–81) and distinctly narrowing posteriorly with pronotum much wider than propodeum
 * comparatively longer legs (HFI 61–69)
 * mesotibia with conspicuous apicoventral spur
 * petiole relatively thick (DPeI 135–173; LPeI 152–194)
 * abdominal terga without any standing pilosity, only with appressed pubescence

Discothyrea poweri is one of the more conspicuous species within the Afrotropical traegaordhi complex. Generally, it is a relatively large species with long legs, long antennae, and an exceptionally thick petiole. It is one of the largest species of the complex together with Discothyrea aisnetu and Discothyrea gaia. Compared to most other Afrotropical Discothyrea, the antennae of D. poweri appear especially elongate due to the relatively distinct flagellomeres and narrow apical club. The presence of a distinct mesotibial spur distinguishes it from most species of the complex, except for D. gaia and Discothyrea traegaordhi. The latter species is the only other member of the complex also occurring in South Africa, but it is easily distinguished from D. poweri on the basis of smaller body size (WL 0.51–0.57 vs. WL 0.67–0.84), a thinner petiole (DPeI 235–289 vs. DPeI 135–173; LPeI 236–313 vs. LPeI 152–194), and shorter antennal scapes (SI 50–55 vs. SI 61–68). Discothyrea gaia appears to be morphologically close to D. poweri but can be separated by the presence of standing pilosity on the abdominal terga. In addition, D. gaia also has shorter legs (HFI 54–58 vs. HFI 61–69) and a thinner petiole (DPeI 192–255 vs. DPeI 135– 173; LPeI 194–264 vs. LPeI 152–194). Nevertheless, it seems as if D. poweri belongs to a natural clade with D. gaia and D. traegaordhi, which is restricted in its distribution to Southern Africa.

There is some noticeable size variation within this species (WL 0.67– 0.84) not seen in most other congeners. This size variation is also visible when comparing eyes. In larger specimens there are considerably more ommatidia than in smaller specimens, in which the eyes superficially appear smaller. However, after measuring it becomes clear that eye size is constant and not correlated with body size (OI 7–10). The shape of the subpetiolar process is also somewhat variable.

Distribution based on Regional Taxon Lists
Afrotropical Region: South Africa, Zimbabwe.

Nomenclature

 * . Pseudosysphincta poweri Arnold, 1916: 162, figs. 9, 9a (w.) SOUTH AFRICA.
 * Type-material: holotype worker.
 * Type-locality: South Africa: Kimberley, 1912 (Power).
 * Type-depository: SAMC.
 * Combination in Discothyrea: Brown, 1958g: 253.
 * Status as species: Wheeler, W.M. 1922a: 762; Brown, 1958g: 253, 341; Bolton, 1995b: 171; Hita Garcia, Lieberman, et al. 2019: 65 (redescription).
 * Distribution: South Africa.

Worker
(n = 10) EL 0.04–0.07; HL 0.59–0.70; HW 0.46–0.57; SL 0.37–0.47; PH 0.31–0.39; DML 0.43–0.55; PW 0.33–0.43; PrH 0.33–0.45; WL 0.67–0.84; HFL 0.42–0.55; PeL 0.13–0.18; PeW 0.23–0.29; PeH 0.26–0.30; LT3 0.38–0.47; LT4 0.41–0.50; OI 7–10; CI 77–84; SI 61–68; LMI 45–46; DMI 45–52; DMI2 72–81; ASI 105–110; HFI 61–69; DPeI 135–173; LPeI 152–194.

Head somewhat longer than broad (CI 77–84), posterior head margin convex, posterodorsal corners of head round, indistinct; in frontal view, sides of head slightly converging anteriorly; eyes relatively large (OI 7–10), round, setose, with several distinct ommatidia, situated almost halfway between anterolateral corner of gena and posterior head margin; eyes visible in frontal view; frontal lamella low, broadly triangular in profile, apex rounded; lamella quite thick apically, weakly translucent, thinner basally but without distinct fenestra; medial clypeus weakly to distinctly convex, slightly prolonged, lateral clypeus curving gently between antennal sockets and anterolateral corners of head; bearing short curved setae. Antenna with moderately long to longer scape (SI 61–68), scape only slightly expanded apically, gently bent; pedicel subcylindrical, longer than broad; apparent antennomere count nine to twelve, flagellomeres basad apical club compressed, taken together only slightly longer than apical club; apical club relatively narrow. Ventral head with low but clearly defined preoccipital ridge without anteromedian carina or with very slight anteromedial prolongation; medial region of hypostoma triangular, arms distinctively narrowed, spatulate apicolaterally; palpal formula not examined. Mandible with a slight preapical swelling and small prebasal denticle; basal angle rounded to squared; ectal face with carina originating at basal angle, becoming confluent with masticatory margin preapically, leaving narrow, curved depressed region.

Mesosoma elongate, gently sloping posteriorly to weakly convex, pronotum slightly higher than propodeum; occasionally metanotal area slightly bulging but not clearly demarcated; in dorsal view mesosoma very thin and elongate (DMI 45–52; DMI2 72–81) and distinctly narrowing posteriorly with pronotum much wider than propodeum; pronotal humeri narrowly rounded; posterior propodeal margin straight; posterodorsal corners of propodeum rounded; declivitious face of propodeum sloping, not concave in profile or oblique posterior view; propodeal spiracle relatively large, directed dorsolaterally; propodeal lobes well-developed, flangelike.

Legs moderately long and robust (HFI 61–69); mesotibia with distinct apicoventral spur; mesobasitarsus relatively short, about equal in length to tarsomeres II–IV taken together.

Petiolar node very thick, rounded-cuneate, not attenuated dorsally, about 1.5 to 1.9 times higher than broad (LPeI 152–194); in profile, anterior face of node sloping posterodorsally, apex thickly rounded, hence posterior face indistinct; in dorsal view, petiole campaniform to trapezoidal, sides divering posteriorly, about 1.4–1.7 times broader than long (DPeI 135–173); in anterior view, petiolar outline rounded, without clear faces; in oblique anterio view, anterior face flat or scarcely impressed medially. Subpetiolar process short, somewhat variable in shape but often rhomboid, sometimes with small digitate projection, with numerous decumbent to erect setae.

Abdominal segment 3 broadly campaniform, widest point just anterad end of segment; tergite more or less evenly convex, sternite poorly rounded to nearly flat in profile; AS3 with low, broad median ridge, somewhat broader posteriorly in ventral view; prora without carina but strongly raised, concave in ventral view, anterolateral corners projecting more strongly; AT4 slightly longer than AT3 (ASI 105–110); AT4 hemidemispherical; AS4 with poorly-developed anterior lip, overlapping median third of AS3, anterior margin straight in ventral view; successive abdominal segments short, telescopic, often concealed.

Sculpture generally reduced; head, petiole, and abdominal segment 3 very shallowly punctulate-reticulate, somewhat more coarsely punctate on gena; mesosoma with sparse, very shallow punctulae; declivitous face of propodeum weakly rugulose to strigulate, particularly on lower half; mandible rather roughly sculptured with piligerous punctae; AT4 somewhat shinier than AT3, punctulae minute and very dense, tergite appearing shagreened.

Setation consisting of abundant but short and fine appressed pubescence more or less evenly distributed over entire body, slightly longer on abdominal terga; standing hairs entirely absent from dorsal surfaces; petiolar sternite and abdominal sternite 3 with fairly long, thick decumbent to suberect hairs; successive abdominal segments with dense, distinctly longer, standing pilosity; ectal face of mandible with abundant, curved, appressed to decumbent setae; masticatory margin with row of straight setae inserted on mesal face.

Color uniformly dull testaceous orange to matte brownish, sometimes with patchy infuscation on head, mesosomal, and abdominal dorsa.

Type Material
See the beginning of this ("Nomenclature") section for detailed information about the specimen types. Additional data and information is also available for a nontype specimen. This includes: volumetric raw data (in DICOM format), 3D rotation video, still images of surface volume rendering, a 3D surface (in PLY format) of a physical specimen (CASENT0764095), stacked digital color images illustrating the head in full-face view, and both profile and dorsal views of the body. The data are deposited at Dryad and can be freely accessed as virtual representations of the type. There is also a Sketchfab 3D surface model of the holotype. It is shown above, in the Caste section, and at Sketchfab (see the link in the Caste Section).

References based on Global Ant Biodiversity Informatics

 * Hita-Garcia F., Z. Lieberman, T. L. Audisio, C. Liu, and E. P. Economo. 2019. Revision of the highly specialized ant genus Discothyrea (Hymenoptera: Formicidae) in the Afrotropics with X-ray microtomography and 3D cybertaxonomy. Insect Systematics and Diversity 3(6): 5:1-84.
 * Koen J. H., and W. Breytenbach. 1988. Ant species richness of fynbos and forest ecosystems in the Southern Cape. South Afr. Tydskr. Dierk. 23(3): 184-188.