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 schulzei can be recognized based on its lack of mesotibial spurs, the presence of an extremely well-developed basal fenestra on the frontal lamella, its standing pilosity, size, and mesosomal shape. As mentioned above, D. schulzei is morphologically very close to Discothyrea damato. Indeed, they are only separable on the basis of setation. It is possible that they are conspecific and the differences in setation are just intraspecific variation. However, we prefer to propose them both as heterospecific for the following reasons. First, major pilosity phenotypes appear to be very stable at species level throughout the Afrotropical Discothyrea fauna. Second, and more importantly, D. damato and D. schulzei are found in sympatry and retain their different pilosity patterns in a very consistent way without any intermediate forms. Other species close to D. schulzei are Discothyrea dryad and Discothyrea wakanda since they agree in most characters. Nevertheless, they differ in body size (despite some overlap), profile of the frontal lamella, and the shape of the subpetiolar process; the mesosoma is similarly stocky in D. schulzei and D. wakanda but more elongate and posteriorly attenuate in D. dryad. The sculpture of D. schulzei is notably deeper than that of either D. dryad or D. damato.

Specimens from Rangiro have slightly longer pilosity than those from Kibale. Otherwise, there is no other noticeable intraspecific variation.

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 = 6) EL 0.00–0.02; HL 0.46–0.54; HW 0.39–0.44; SL 0.25–0.29; PH 0.23–0.29; PW 0.29–0.35; DML 0.29–0.36; PrH 0.29–0.35; WL 0.47–0.56; HFL 0.26–0.33; PeL 0.07–0.08; PeW 0.18–0.21; PeH 0.18–0.24; LT3 0.28–0.33; LT4 0.33–0.39; OI 0–3; CI 81–86; SI 50–56; LMI 49–55; DMI 58–66; DMI2 95–100; ASI 114–124; HFI 55–60; DPeI 234–270; LPeI 263–300.

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. A cyber-type of the holotype is also available. This includes: volumetric raw data (in DICOM format), 3D rotation video, still images of surface volume rendering, a 3D surface (in PLY format) of the physical holotype (: CASENT0790121), 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).

Etymology
The name of the new species is a patronym dedicated to Arne Schulze from Frankfurt, Germany. The first author wants to thank him for his support and friendship during the time of this study. The specific epithet is given as a genitive noun.

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.