Discothyrea oculata

Discothyrea oculata has a wide distribution range.

Identification
Hita-Garcia and Lieberman (2019) - Distinguished from the only other member of the Discothyrea oculata species complex, Discothyrea mixta, by the following combination of characters: larger species (WL 0.75–0.90); narrower head (CI 84–87); larger eyes (OI 14–16); propodeum without strong angles, denticles, or margination; declivitous face of propodeum deeply costate to rugose; longer legs (HFI 73–79); AT4 smooth and unsculptured; scrobal area striate to strigulate, without punctate or alveolate sculpture.

In general, the separation of D. mixta from D. oculata is very easy and both are difficult to mistake for each other. They differ in body size, eye size, and location on the head, as well as the shape of the propodeum and the sculpture on the propodeal declivity.

Discothyrea oculata varies slightly in overall size (WL 0.75–0.90), which is neither surprising nor unusual considering its wide distribution range. There is also some moderate diversity in coarseness of sculpture and number of ommatidia, as well as in the length and abundance of pilosity. Again, as in D. mixta, this is considered as regular intraspecific geographical variation over a wide distribution range. The color ranges trivially from luteous-orange to ferrous red.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun, Central African Republic, Congo , Democratic Republic of Congo, Ghana, Guinea, Ivory Coast, Kenya, Mozambique, Nigeria, United Republic of Tanzania, Zimbabwe.

Biology
Discothyrea oculata appears to have a broad range throughout most of the Afrotropical region, even though it is represented by fairly sparse records. Preferred habitats are drier, more open, and usually at lower elevations than in Discothyrea mixta, including open patches of forest, dry coastal forest, and even grassland, while it is less often found in dense rainforests. The apparent rarity from museum collections is at odds with the results of Dejean and Dejean (1998) who studied this species extensively in the field and laboratory, suggesting that D. oculata may be rather common but difficult to collect with standard sampling methodology. Nearly 200 colonies in southern Cameroon were observed within oothecae of segestriid spiders of the genus Ariadna, while laboratory colonies provided with oothecae manipulated the silk to line and operculate their test-tube nests. Successful foundresses did not produce a generation of nanitics, leading the authors to term this highly derived form of colony foundation ‘claustral lestobiotic colony founding’. Similar to D. mixta, D. oculata only accepted spiderlings and eggs in foraging experiments, while ignoring all other potential prey items (Dejean and Dejean 1998).

Nomenclature

 * . Discothyrea oculata Emery, 1901a: 52 (w.q.m.) CAMEROON.
 * Type-material: lectotype worker (by designation of Hita Garcia, Lieberman, et al. 2019: 24), 5 paralectotype workers.
 * Type-locality: lectotype Cameroon: (no further data), 1895 (L. Conradt); paralectotypes with same data..
 * Type-depositories: MSNG (lectotype); MHNG, NHMB, NHMW (paralectotypes).
 * Status as species: Santschi, 1910c: 351; Emery, 1911d: 52; Santschi, 1914d: 312; Wheeler, W.M. 1922a: 761; Arnold, 1926: 197; Bernard, 1953b: 186; Smith, M.R. & Wing, 1955: 107; Brown, 1958g: 253, 340; Leston, 1971: 117; Bolton, 1995b: 171; Hita Garcia, Lieberman, et al. 2019: 24 (redescription).
 * Senior synonym of sculptior: Hita Garcia, Lieberman, et al. 2019: 24.
 * Distribution: Cameroon, Congo, Democratic Republic of Congo, Ghana, Guinea, Ivory Coast, Kenya, Mozambique, Nigeria, Tanzania, Zimbabwe.
 * sculptior. Discothyrea oculata var. sculptior Santschi, 1913c: 302 (w.) CONGO.
 * Type-material: 4 syntype workers.
 * Type-locality: Congo (“Congo français”): Brazzaville, 1907 (A. Weiss).
 * Type-depository: NHMB.
 * Subspecies of oculata: Wheeler, W.M. 1922a: 761; Smith, M.R. & Wing, 1955: 107.
 * Status as species: Brown, 1958g: 253; Bolton, 1995b: 171.
 * Junior synonym of oculata: Hita Garcia, Lieberman, et al. 2019: 24.

Worker
Hita-Garcia and Lieberman (2019) - (n = 10) EL 0.12–0.15; HL 0.83–0.93; HW 0.70–0.78; SL 0.58–0.70; PH 0.44–0.51; PW 0.55–0.65; DML 0.51–0.63; PrH 0.53–0.59; WL 0.75–0.90; HFL 0.58–0.69; PeL 0.15–0.21; PeW 0.36–0.45; PeH 0.37–0.41; LT3 0.71–0.81; LT4 0.38–0.48; OI 14–16; CI 84–87; SI 69–76; LMI 54–58; DMI 66–78; DMI2 102–108; ASI 53–60; HFI 73–79; DPeI 201–275; LPeI 195–258.

Head broader than long (CI 84–87), posterior head margin strongly convex, evenly curving into sides, such that posterodorsal corners of head indistinct; sides of head in frontal view converging anteriorly; eyes large and well developed, setose (OI 14–16), comprising around 30 ommatidia; ommatidia globose, silvery, eyes protruding from head, visible in frontal view; eyes situated anterolaterally on gena, slightly anterad halfway between anterolateral corner of gena and posterior head margin; frontal carinae produced as broad, elevated plate; rhomboid in frontal view, extending to around posterior third of head, widest point at around anterior eye margin, broad at posterior attachment to head, pointed anteriorly; in profile rooflike, forming broad, deeply depressed scrobal area extending to just anterad eye; anteromedially reduced to thin, translucent septum between antennal sockets; posterolateral portion of torulus flangelike, reduced posteromedially, thus confluent with deep, exposed antennal acetabulum; scrobe strigulate to laterally striate; medial clypeus rectangular, strongly projecting, anterior margin transverse, bearing very dense layer of appressed to decumbent white pilosity, sides of medial clypeus subparallel laterad antennal sockets. Antenna with long scape (SI 69–76), scape somewhat expanded apically, slightly bent; pedicel a short cylinder, broader than long; true antennomere count nine; apparent antennomere count nine to twelve; flagellomeres basad apical club highly compressed, taken together approximately as long as apical club. Ventral head surface with two low but prominent rounded tumuli situated laterally, slightly posterad midline (in profile); postoccipital ridge with small anteromedian carina, extending less than one-fourth of the way between occipital foramen and posteromedial extent of hypostoma; medial region of hypostoma triangular, hypostomal arms slightly narrowed, similar in width throughout their length; palpal formula 6,4 (Keller 2011). Mandible edentate; basal angle rounded; with blunt prebasal angle; ectal face with longitudinal carina extending from prebasal angle to apex, carina becoming confluent with masticatory margin slightly less than halfway along masticatory margin, leaving short comma-shaped to triangular, depressed, unsculptured medial region on masticatory margin.

Mesosoma robust, evenly convex, pronotum scarcely higher than propodeum; in dorsal view, mesosoma broad and stout (DMI 66–78; DMI2 102–108) and distinctly narrowed posteriorly, pronotum distinctly wider than propodeum; pronotal humeri obliquely rounded; posterior propodeal margin straight; posterodorsal corners of propodeum rounded, lacking denticles; declivitous face of propodeum slightly concave in profile and oblique posterior view; propodeal spiracle small but distinct, offset by unsculptured annulus around spiracular opening, directed posterolatearally; propodeal lobes rather short and rounded.

Legs quite long (HFI 73–79) and robust; mesotibia with short but distinct apicoventral spur.

Petiolar node thickly disciform, not attenuated dorsally, about 2.0 to 2.6 times higher than broad (LPeI 195–258); in profile anterior face of node distinctly convex, curving smoothly over dorsum, without distinct apex; posterior face of node vertical; in dorsal view, node roughly a rounded trapezoid, sides strongly diverging posteriorly, anterior margin convex, posterior margin concave, about 2.0 to 2.75 times broader than long (DPeI 201–275); in anterior view, petiolar outline subcircular; in oblique anterodorsal view anterior face convex; in ventral view, broad and roughly campaniform, sides weakly curved; subpetiolar process short, lobate to subquadrate.

Abdominal segment 3 asymmetrically campaniform, tergite evenly convex, widest posteriorly; AS3 somewhat flat to bulging posteriorly, deepest posteriorly, with moderatlely concave anteromedial region of reduced sculpture bordered anteriorly by strongly carinate, laterally broad prora; AT3 approximately twice as long as AT4 (ASI 53–60); AT4 hemidemipsherical to semicylindrical, gently recurved, spiracle sometimes exposed, small but prominent; successive abdominal segments short, telescopic, often concealed.

Sculpture on head, mesosoma, petiole, and abdominal segment 3 alveolate, alveoli giving rise to one or several setae; coarseness of sculpture somewhat variable, equivalently developed on all tagma, or often deeper on head and/or weaker on mesosoma; ventral head surface posteromedially with significantly reduced sculpture, only a few scattered foveae present; scape sparsely foveate; declivitous face of propodeum deeply costate to rugose; AT4 and succesive abdominal segments very smooth (unsculptured except for inconspicuous, microscopic piligerous punctulae, appearing polished relative to rest of body); mandible with numerous piligerous punctae.

Setation fairly consistent on dorsal surfaces of head, mesosoma, and petiole, a dense layer of appressed to decumbent white setae; gena and lateral mesosoma sometimes with sparser setation; density of setae somewhat variable between individuals; scrobal area glabrous and shining; AT3 evenly setose over its dorsal and lateral surfaces, setation shorter and less dense than on mesosoma, not forming distinct dorsal layer; AT4 with long, abundant, but fine appressed pubescence; successive abdominal segments with dense, flocculent, erect yellowish setae; ectal face of mandible with fine, curved, appressed to decumbent setae; masticatory margin with row of stout, spatulate setae on mesal face; legs with fairly dense but relatively fine and entirely appressed white pubescence.

Color iron-red, testaceous- to luteous-orange; legs and abdominal segments four through seven orange to yellowish, lighter than remainder of body.

References based on Global Ant Biodiversity Informatics

 * Arnold G. 1926. A monograph of the Formicidae of South Africa. Appendix. Annals of the South African Museum. 23: 191-295.
 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * Bernard F. 1953. La réserve naturelle intégrale du Mt Nimba. XI. Hyménoptères Formicidae. Mémoires de l'Institut Français d'Afrique Noire 19: 165-270.
 * CSIRO Collection
 * 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.
 * IZIKO South Africa Museum Collection
 * Leston D. 1971. The Ectatommini (Hymenoptera: Formicidae) of Ghana. Journal of Entomology. Series B 40: 117-120.
 * Lévieux J. 1972. Les fourmis de la savane de Lamto (Côte d'Ivoire): éléments de taxonomie. Bulletin de l'Institut Fondamental d'Afrique Noire. Série A. Sciences Naturelles 34: 611-654.
 * Santschi F. 1910. Formicides nouveaux ou peu connus du Congo français. Annales de la Société Entomologique de France 78: 349-400.
 * Santschi F. 1914. Formicides de l'Afrique occidentale et australe du voyage de Mr. le Professeur F. Silvestri. Bollettino del Laboratorio di Zoologia Generale e Agraria della Reale Scuola Superiore d'Agricoltura. Portici 8: 309-385.
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004
 * Yeo K., S. Konate, S. Tiho, and S. K. Camara. 2011. Impacts of land use types on ant communities in a tropical forest margin (Oumé - Cote d'Ivoire). African Journal of Agricultural Research 6(2): 260-274.