Discothyrea schulzei

At present, Discothyrea schulzei is only known from Rangiro in Rwanda and Kibale Forest and Semliki National Park in Uganda. The former two localities are rainforest sites at elevations ranging from 1510 to 1800 m while the latter is moist semideciduous forest with patches of swamp forest between 670 and 760 m. Based on the collection data from the Kibale specimens, the species lives in leaf litter. We strongly suspect that the species will be found in more rainforests along the Albertine Rift in Burundi, Rwanda, and Uganda.

Identification
Hita-Garcia and Lieberman (2019) - The following character combination distinguishes D. schulzei from the remainder of the complex:
 * smaller species (WL 0.47–0.56)
 * in profile frontal lamella with anterodorsal corner rounded, with conspicuous, large, basal fenestra
 * moderately long, distinct, well-spaced and almost entirely erect pilosity present on mesosoma and abdominal tergites
 * in dorsal view mesosoma conspicuously thick, robust and stocky (DMI 58–66; DMI2 95–100)
 * anterolateral corner of gena weakly angled and not denticulate/dentate
 * mesosoma not extremely convex and propodeum denticulate/dentate
 * masticatory margin of mandible edentate
 * mesotibia without apicoventral spur
 * subpetiolar process long, dentate to spinose with rounded apex
 * AT4 around 1.1 to 1.2 times longer than AT3 (ASI 114–124)
 * abdominal sternite 3 rounded, without any projecting lobe
 * anterior clypeal margin without conspicuous row of long, straight setae

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: Rwanda, Uganda.

Nomenclature

 * . Discothyrea schulzei Hita Garcia & Lieberman, in Hita Garcia, Lieberman, et al. 2019: 68, figs. 4Q, 6Q-12Q, 14Q, 52, 53 (w.) RWANDA, UGANDA.
 * Type-material: holotype worker, 3 paratype workers.
 * Type-locality: holotype Rwanda: Western, Rangiro (2.39361, 29.18278), 1800 m., ANTC37497, 6.viii.1973, litter (P. Werner); paratypes: 2 workers with same data, 1 worker with same data but ANTC24124, 10.vii.1973.
 * Type-depositories: BMNH (holotype); CASC, MHNG (paratypes).
 * Distribution: Rwanda, Uganda.

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 longer than broad (CI 81–86), posterior head margin straight; posterodorsal corners of head rounded; in frontal view, sides of head converging gently anteriorly; eyes absent or very small (OI 0–3), an indistinct pigmented spot, situated slightly anterad one-third of the way between anterolateral corner of gena and posterior head margin, not visible in frontal view; frontal lamella lobate in profile, with anterodorsal corner rounded; lamella with conspicuous, large, basal fenestra; medial clypeus convex, lateral clypeus curving fairly strongly between antennal sockets and anterolateral corners of head, bearing short curved to erect setae. Antenna with moderately long scape (SI 50–56), scape moderately incrassate, gently bent; pedicel campaniform, slightly longer than broad; apparent antennomere count nine to eleven, flagellomeres basad apical club highly compressed, taken together only about as long as apical club. Ventral head with fairly low, sinuate preoccipital ridge with short, triangular anteromedial projection; median region of hypostoma triangular, arms only very slightly narrowed, squared apicolaterally; palpal formula not examined. Mandible edentate except for curved prebasal denticle; basal angle rounded; ectal face with carina confluent with masticatory margin for most of its length, leaving only a small depressed region containing prebasal denticle.

Mesosoma weakly convex, pronotum only scarcely higher than propodeum; in dorsal view, mesosoma conspicuously thick, robust and stocky (DMI 58–66; DMI2 95–100), slightly narrowed posteriorly, pronotum not much wider than propodeum; pronotal humeri rounded; posterior propodeal margin concave; posterodorsal corners of propodeum rounded; declivitous face of propodeum distinctly concave in profile and oblique posterior view; propodeal spiracle inconspicuous, directed posterodorsally; propodeal lobes moderately well-developed, lobate.

Legs short to moderately long (HFI 55–60); mesotibia without apicoventral spur; with small but distinct seta inserted in apicoventral pit; mesobasitarsus quite short, shorter than tarsomeres II–IV taken together.

Petiolar node not strongly attenuated dorsally, somewhat blunt in profile, about 2.6 to 3.0 times higher than long (LPeI 263–300); in profile anterior face of node sloping posterodorsally, apex rounded, posterior face sloping posteroventrally; in dorsal view, petiole rounded-rectangular, anterior margin and sides convex, posterior margin concave; about 2.3 to 2.7 times broader than long (DPeI 234–270); in anterior view, petiolar outline, edges and angles well-defined; in oblique anterior view, anterior face flat; subpetiolar process long, dentate to spinose with rounded or truncate apex.

Abdominal segment 3 campaniform, tergite somewhat prolonged anteriorly past anterior sternal margin; sternite convex in profile; AS3 with short, low anterior median ridge, with broad posterior lobe; prora carinulate, concave in ventral view; AT4 around 1.1 to 1.2 times longer than AT3 (ASI 114–124); AT4 hemidemispherical; AS4 with broad, well-developed anterior lip, overlapping most of the width of AS3, anterior margn straight in ventral view; successive abdominal segments short, telescopic, often concealed.

Sculpture on head, mesosomal dorsum, petiole, and dorsal surface of AT3 coarsely foveolate-reticulate to alveolate, more sparsely so on lateral mesoma and abdominal segment 3; gena becoming somewhat more punctate to foveolate on ventral head surface; mandible roughly sculptured with piligerous punctulae; coarse sculpture persistent on frontal lamella and clypeus; rugulae present on lower portions of lateral mesosoma; declivitous face of propodeum longitudinally rugulose to costulate; AT4 distinctly smoother and shinier than AT3, with abundant but fine piligerous punctulae.

Setation on head, mesosoma, petiole, and AT3 consisting of fine, dilute appressed pubescence on lateral surfaces, dorsal surfaces with distinct, abundant, erect white pilosity; abdominal sternite 3 and AT4 similarly setose, but pubescence longer and more distinct on lateral surfaces, and erect pilosity somewhat longer on AT4; successive abdominal segments with similar pattern, pubescence and pilosity equivalent to or slightly longer and more abundant than on AT4; scape and legs with evenly distributed, dense, appressed pubescence; ectal face of mandible with relatively short, curved, appressed to decumbent setae; masticatory margin with row of straight setae.

Color rather dull testaceous-yellow to reddish, chestnut brown, appendages usually lighter.

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.