Discothyrea penthos

Discothyrea penthos is only known from four rainforest localities in Ivory Coast where it seems to live in leaf litter. This is the only species apparently endemic to the Guinean rainforests of West Africa.

Identification
Hita-Garcia and Lieberman (2019) - The following character combination distinguishes D. penthos from the remainder of the complex:
 * masticatory margin of mandible edentate
 * anterior clypeal margin usually asetose or with only short, inconspicuous setae
 * anterolateral corner of gena sharply demarcated but not dentate
 * in dorsal view mesosoma conspicuously thick, robust and stocky (DMI 62–65; DMI2 94–95)
 * mesotibiae without apicoventral spur
 * propodeum dentate, teeth relatively large and subtended by narrow lamellulae
 * abdominal sternite 3 produced as squared to trapezoidal lobe, with distinct anterior, ventral, and posterior surfaces in profile
 * AT4 only weakly longer than AT3 (ASI 105–112)
 * erect pilosity absent on all dorsal surfaces

The original description does not provide any significant details that could distinguish D. patrizii from other traegaordhi - complex species, and Weber (1949) listed antennomere count (an unstable character; see Materials and Methods) and the shape of the frontal lamella as diagnostic features delineating the species from Discothyrea traegaordhi and Discothyrea hewitti. The paratype specimen however, while in less than ideal condition, is well enough preserved to associate it with recently collected material, from which a thorough description and diagnosis are possible. Despite the apparent rarity prior to this study, after association of most of the unidentified material to the type, D. patrizii turns out to be widespread in East Africa.

Varies most noticeably in color, which ranges from uniformly matte orange to dark earthy brown with yellowish appendages, as in many Tanzanian individuals. Pubescence is not highly variable in development, but is much less conspicuous on lighter morphs, while contrasting in darker forms. The subpetiolar process is quite variable, too, ranging from dentate with apex acute to broadly lobate, with apex rounded.

Distribution based on Regional Taxon Lists
Afrotropical Region: Ivory Coast.

Nomenclature

 * . Discothyrea penthos Hita Garcia & Lieberman, in Hita Garcia, Lieberman, et al. 2019: 62, figs. 4O, 6O-12O, 14O, 48, 49 (w.) IVORY COAST.
 * Type-material: holotype worker, 7 paratype workers.
 * Type-locality: holotype Ivory Coast: Monogaga (4.81833, -6.49028), ca 20 m., ANTC42121, 24.x.1980 (V. Mahnert & J.L. Perret); paratypes with same data.
 * Type-depositories: BMNH (holotype); BMNH, CASC, MCZC, MHNG, SAMC (paratypes).
 * Distribution: Ivory Coast.

Worker
Hita-Garcia and Lieberman (2019) - (n = 15) EL 0.03–0.04; HL 0.38–0.54; HW 0.30–0.47; SL 0.19–0.30; PH 0.19–0.28; DML 0.26–0.39; PW 0.23–0.33; PrH 0.23–0.34; WL 0.40–0.57; HFL 0.22–0.35; PeL 0.04–0.07; PeW 0.16–0.22; PeH 0.16–0.22; LT3 0.28–0.40; LT4 0.24–0.38; OI 5–8; CI 78–87; SI 50–58; LMI 44–50; DMI 52–58; DMI2 78–87; ASI 85–98; HFI 54–63; DPeI 314–489; LPeI 314–467.

Head broad (CI 84–87); posterior head margin straight, posterodorsal corners of head broadly rounded. In frontal view sides of head subparallel to slightly convex; head appearing subquadrate posterad antennal sockets; eyes very small (OI 2–4) but distinct and round, situated about a third of the way between anterolateral corner of gena and posterior head margin; eyes just visible in frontal view; anterolateral corner of gena sharply demarcated, approximately right-angled, sometimes slightly projecting laterally; frontal lamella roughly rhomboid in profile, with three distinct edges: anterior edge shortest, sloping posterodorsally; dorsal edge longest, sloping dorsally; lamella thinner and more translucent basally but without distinct fenestra; medial clypeus convex, lateral clypeus curving fairly strongly between antennal sockets and anterolateral corners of head, bearing numerous short curved setae. Antenna with moderately long scape (SI 52–57), scape moderately incrassate, gently bent; pedicel subglobose, broader than long; true antennomere count eleven; apparent antennomere count nine to twelve; flagellomeres basad apical club highly compressed, taken together only about as long as apical club. Ventral head with well-developed, sinuate preoccipital ridge with short, triangular anteromedian carina; medial region of hypostoma rounded, arms wide, spatulate apicolaterally; palpal formula not examined. Mandible with a small subapical angle; basal angle rounded to angulate; ectal face with weak carina extending from subapical angle to basal angle, leaving narrow, curved, depressed region.

Mesosoma in dorsal view conspicuously thick, robust and stocky (DMI 62–65; DMI2 94–95); evenly convex, pronotum only slightly higher than propodeum; in dorsal view, mesosoma narrowed posteriorly, pronotum distinctly wider than propodeum, inclusive of laterally divergent propodeal dentae; pronotal humeri somewhat narrowly rounded; posterior propodeal margin strongly concave; posterodorsal corners of propodeum dentate, dentae large, triangular, laterally flattened, mostly opaque, subtended by narrow but darkly pigmented lamellulae outlining propodeal concavity, hence propodeum laterally marginate; declivitous face of propodeum strongly concave in profile and oblique posterior view; propodeal spiracle large, directed posterodorsally; spiracle conspicuous due to polished, unsculptured area posterodorsad spiracle, extending to base of propodeal tooth, strongly contrasting with surrounding foveolate sculpture; propodeal lobes well-developed, flangelike.

Legs moderately long (HFI 61–68) and slender; mesotibia without apicoventral spur or seta; mesobasitarsus relatively short, about as long as tarsomeres II–IV taken together.

Petiolar node strongly attenuated dorsally, but appearing thick in profile since attenuation strongest medially; node about 3.0 to 3.8 times higher than long (LPeI 300–383); in profile, anterior face of node convex, apex blunt to rounded, curving evenly into convex posterior face, hence posterior face indistinct; in dorsal view, petiole roughly trapezoidal, sides divergent posteriorly, anterior face concave, about 3.3 to 4.3 times broader than long (DPeI 329–429); in anterior view, petiolar outline roughly pentagonal, edges poorly defined, angles strongly rounded; in oblique anterodorsal view, anterior face concave; subpetiolar process broadly falcate, curved, apex rounded.

Abdominal segment 3 with tergite broadly campaniform, widest just anterad end of segment; sternite somewhat squared in profile; AS3 with wide median ridge extending anteriorly to prora, broadening to lobe posteriorly; prora well-defined, concave in ventral view; constriction between abdominal segments 3 and 4 distinct; AT4 weakly longer than AT3, about 1.1 times longer (ASI 105–112); AT4 bulbous, hemidemispherical; AS4 with well-developed, wide anterior lip, overlapping most of the width of AS3, anterior border weakly convex in ventral view; successive abdominal segments short, telescopic, often concealed.

Sculpture similarly foveolate on head, dorsal mesosoma, declivitous face of propodeum, petiole, abdominal segment 3 and AT4; foveolae becoming smaller on front of head; becoming foveolate-reticulate on lateral mesosoma; area posterodorsad propodeal spiracle smooth and unsculptured; mandible with numerous, fine piligerous punctulae.

Setation very dilute and inconspicuous, consisting entirely of appressed pubescence, slightly longer on abdominal terga; body appearing glabrous at lower magnification; metapleural gland bulla with distinctly longer but fine, yellowish guard setae; scape and legs with short, somewhat sparse velvety appressed pubescence; ectal face of mandible with relatively long, curved, appressed setae; masticatory margin with row of short, straight seate.

Color more or less uniformly bright luteous-orange to yellowish.

Type Material
Hita-Garcia and Lieberman (2019) - Despite an intensive search in the MCZC collection in collaboration with the curatorial staff, the holotype was not to be found and is presumably lost. Fortunately, however, the paratype was available for examination. In this case, we refrain from designating a neotype since the identity of D. patrizii is clear and stable.

See the beginning of this ("Nomenclature") section for detailed information about the specimen types. A cyber-type of a nontype specimen is also available. This includes: Volumetric raw data (in DICOM format), 3D rotation video, still images of surface volume rendering, and 3D surface (in PLY format) of a physical nontype specimen (CASENT0235472) in addition to stacked digital color images illustrating the head in full-face view, plus profile and dorsal views of the body. The data are deposited at Dryad and can be freely accessed as virtual representations of the species. There is also a Sketchfab 3D surface model of this nontype specimen. 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.