Key to Afrotropical Discothyrea

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This worker key is based on: Hita-Garcia, F., Lieberman, Z., Audisio, T.L., Liu, C., Economo, E.P. 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 (doi:10.1093/isd/ixz015).

For more information on Afrotropical Ants see: Afrotropical ant genera Identification resources for Afrotropical Ants including resources and keys and the Afrotropical Region Species List

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1

  • Frontal carinae produced as a broad, elevated rhomboid plate, roof-like in profile (Fig. 5A and B); antennal scrobes present, deep, extending from antennal insertions to just anterad the eye (Fig. 5E and F); eye present, well-developed with multiple silvery globose ommatidia protruding from head (even when eye small) (Fig. 6A and B); AT3 much longer than AT4, around 1.9 to 2.2 times (ASI < 60) (Fig. 2A). (D. oculata-complex). . . . . 2
  • Frontal carinae reduced to thin medial lamella, broadly lobate to acutely triangular in profile (Fig. 5E and F); antennal scrobes absent (Fig. 5E and F); eye variable: either absent, a simple pigmented spot, or if with multiple ommatidia, if the latter then eye small and ommatidia flattened, not protruding from head (Fig. 6C–T); AT3 never as long as above, usually AT3 equal in length or shorter than AT4, sometimes AT3 up to 1.2 times longer than AT4 (ASI 85–168) (Fig. 2B and C). [D. traegaordhi complex] . . . . . 3

2

return to couplet #1

  • Eyes small (OI 5–9), situated laterally on gena (Figs. 6A and 7A); propodeum angulate to dentate, angles subtended and medially joined by narrow carinulae such that propodeum laterally and dorsally marginate (Fig9A); propodeal declivity with median carina but without costae or rugae (Fig. 11A). [Angola, Cameroon, Central African Republic, Democratic Republic of Congo, Ghana, Ivory Coast, Kenya, Liberia, Mozambique, Tanzania, South Africa, Uganda]. . . . . Discothyrea mixta
Discothyrea mixta casent0178268 profile 1.jpg
  • Eyes large (OI 14–16), situated anterolaterally on gena (Figs. 6B and 7B); propodeum not angulate or dentate (though declivity concave), lacking carinulae and not marginate (Fig. 9B); propodeal declivity deeply costate to rugose. (Fig. 11B). [Cameroon, Democratic Republic of Congo, Ghana, Guinea, Ivory Coast, Kenya, Mozambique, Nigeria, Tanzania, Zimbabwe]. . . . . Discothyrea oculata
Discothyrea oculata sam-hym-c005413 profile 1.jpg

3

return to couplet #1

  • Mesotibia with conspicuous apicoventral spur (Fig. 13A–C). . . . . 4
  • Mesotibia without a conspicuous apicoventral spur; either apically unarmed or with small, distinct seta inserted in apicoventral pit (Fig. 13D–F). . . . . 6

4

return to couplet #3

  • Dense layer of appressed pubescence with numerous short, but conspicuously standing setae present on abdominal terga (Figs. 14H and 33A); mandible without prebasal angle or denticle (Fig. 8H). [Zimbabwe] . . . . . Discothyrea gaia
D gaia hal.jpg
  • Abdominal terga without any standing setae, only with appressed pubescence (Fig. 14P and R); mandible with small prebasal denticle (Fig. 8P) or prebasal irregularly shaped median carina (Fig. 8R). . . . . 5

5

return to couplet #4

  • Generally larger species (WL 0.67–0.84); antennal scapes longer (SI 61–68); legs longer (HFI 61–69); petiole exceptionally thick (DPeI 135–173; LPeI 152–194) (Figs. 50A, B, and 51L); mandible with small, sharp prebasal denticle (8P); sculpture shallow overall, especially smooth on clypeus, propodeal declivity, petiole, and AT3 (Figs. 6P, 9P, 10P, and 12P). [South Africa]. . . . . Discothyrea poweri
Discothyrea poweri sam-ent-0011509 profile 1.jpg
  • Generally smaller species (WL 0.51–0.57); antennal scapes shorter (SI 50–55); legs shorter (HFI 54–58); petiole thinner (DPeI 235–289; LPeI 236–313) (Figs. 54A, B, and 55L); mandible with broad prebasal irregularly shaped median carina (Fig. 8R); sculpture coarser overall, especially on clypeus, propodeal declivity, petiole, and AT3 (Figs. 6R, 9R, 10R, 12R). [South Africa] . . . . . Discothyrea traegaordhi
Discothyrea hewitti sam-hym-c000061a profile 1.jpg

6

return to couplet #3

  • Larger species (HW 0.57–0.61; WL 0.80–0.90); mesosoma high-rounded, profile extremely convex (Fig. 9C); propodeum rounded to weakly angulate; first mesotarsomere very elongated, about as long as remaining tarsomeres taken together (Fig. 24R). [Tanzania]. . . . . Discothyrea aisnetu
Aisnetu hal.jpg
  • Smaller species (HW 0.30–0.49; WL 0.38–0.59); mesosomal profile usually ranging from almost flat to weakly moderately convex (Fig. 9D, F, G, J–M, Q, and T); if mesosoma well rounded, then propodeum conspicuously dentate (Fig. 9O and S); first tarsomere variable in length but never as long as above, usually subequal to tarsomeres II–IV taken together (Figs. 26R, 28R, 32R, 36R, 38R, 40R, and 57R). . . . . 7

7

return to couplet #6

  • Masticatory margin of mandible with a prominent, well developed preapical tooth, clearly larger than prebasal denticle or acute basal angle (8E, I); head very broad, subquadrate (CI 87–92), anterolateral corners of gena angulate to denticulate (Fig. 6E and I). . . . . 8
  • Masticatory margin of mandible without preapical tooth, or if small preapical denticle or angle present, then not well-developed and not clearly larger than prebasal denticle or acute basal angle (Fig. 8D, F, G, J–M, O, Q, S, T); head not as above: usually not as broad (CI 77–89), and anterolateral corner of gena not angulate (Fig. 6D, F, G, J, L, M, O, Q, S, T); if gena somewhat angulate, then head especially elongate (CI 78) (Fig. 6K). . . . . 9

8

return to couplet #7

  • Dorsal surfaces and antennal scape without standing pilosity, with appressed or decumbent pubescence only (Figs. 14E and 27A); medial clypeus transverse in frontal view (Fig. 6E); eye larger (OI 6); preapical mandibular tooth exceptionally large, strongly curved; apical angle of mandible acute (Fig. 8E). [Tanzania]. . . . . Discothyrea chimera
D chimera hal.jpg
  • Standing pilosity present and abundant on all dorsal surfaces and antennal scape (Figs. 14I and 35A); medial clypeus emarginate in frontal view (Fig. 6I); eye absent or tiny (OI 0–4); preapical mandibular tooth smaller and not strongly curved; apical angle of mandible squared to notched (Fig. 8I). [Rwanda, Tanzania]. . . . . Discothyrea gryphon
D gryphon hal.jpg

9

return to couplet #7

  • AT4 conspicuously enlarged, bulbous, much larger and longer than AT3 (ASI 158–183) (Fig. 12S); posterior propodeum laterally and dorsally strongly concave; declivitous face of propodeum mostly smooth, ventral portion transversely substrigulate, clearly differently sculptured than remainder of mesosoma. [Angola, Cameroon, Ghana, Ivory Coast, Uganda] . . . . . Discothyrea venus
D venus hal.jpg
  • Character combination never as above; AT4 equal in length to AT3, or if longer then ratio smaller (ASI 100–142) (Fig. 12D, F, G, J–M, O, Q, and T); posterior propodeum variably shaped; declivitous face of propodeum variable, but usually entire surface well-sculptured or entire surface smooth . . . . . 10

10

return to couplet #9

  • Mesosomal and abdominal dorsa with standing pilosity (sometimes best seen in silhouette or on AT4 in dorsal view, but visible at low magnification) (Fig. 14G, M, Q, T, 31A, 43A, 52A, and 58A). . . . . 11
  • Usually mesosomal and abdominal dorsa without standing pilosity, sometimes abdominal dorsa with short, standing pilosity, but then no standing pilosity on dorsum of mesosoma (Figs. 14D, F, J–L, N, O, 25A, 29A, 37A, 39A, 46A, and 48A). . . . . 14

11

return to couplet #10

  • Propodeum strongly dentate with deeply concave declivity (Fig. 9M); abdominal sternite 3 with strong median ridge anteriorly surpassing prora, appearing distinctly rectangular in profile (Fig. 12M); petiolar outline rectangular with pointed dorsolateral angles, anterior face of petiolar node strongly impressed, appearing bilobed in oblique anterior view (Fig. 44M and N). [Tanzania]. . . . . Discothyrea michelae
D michelae hal.jpg
  • Propodeum denticulate to weakly dentate with only moderately concave declivity (Fig. 9G, Q, and T); abdominal sternite 3 without a median ridge or if ridge present, not anteriorly surpassing prora, sternite not rectangular in pofile (Fig. 12G, Q, and T); petiole pentagonal to hexagonal, never rectangular, anterior face of petiolar node flat to weakly impressed, never appearing bilobed in oblique anterior view (Figs. 32M, N, 53M, N, and 59M, N). . . . . 12

12

return to couplet #11

  • Mesosoma comparatively elongate and slender (DMI2 87–91; LMI 45–49) (Fig. 10G); frontal lamella bladelike, apex angulate in profile. [Kenya]. . . . . Discothyrea dryad
D dryad hal.jpg
  • Mesosoma comparatively robust and stocky (DMI2 93–100; LMI 49–57) (Fig. 10Q and T); frontal lamella disciform to lobate, apex rounded in profile. . . . . 13

13

return to couplet #12

  • Smaller species (WL 0.47–0.56; HW 0.39–0.44) with eyes smaller or absent (OI 0–3) (Fig. 7Q) and shorter legs (HFI 55–60); sculpture similarly coarse overall, not notably reduced on petiole or abdominal sternite 3 (Figs. 12Q and 59Q). [Rwanda, Uganda]. . . . . Discothyrea schulzei
D schulzei hal.jpg
  • Larger species (WL 0.59–0.65; HW 0.50–0.52) with larger eyes (OI 4–7) (Fig. 7T) and longer legs (HFI 63–68); sculpture on petiole and abdominal segment 3 reduced (Fig. 12T), abdominal sternite 3 very smooth medially (Fig. 59T). [Democratic Republic of Congo] . . . . . Discothyrea wakanda
D wakanda hal.jpg

14

return to couplet #10

  • Surface sculpture very reduced, entire body quite smooth with only minute, shallow punctulation (Fig. 9N); propodeum not strongly angulate or denticulate (Fig. 9N) [Kenya, Tanzania]. . . . . Discothyrea patrizii
Discothyrea patrizii type hal.jpg
  • Surface sculpture on head, mesosoma, and AT3 well-developed and coarse, predominantly punctate to foveolate-reticulate (Fig. 9D, F, J–L, and O); propodeum angulate to strongly denticulate (Fig. 9D, F, J–L, and O). . . . . 15

15

return to couplet #14

  • Mesosoma robust and stocky (DMI2 92–102; LMI 47–56) (Fig. 10D, F, and O); head broader (CI 79–89) (Fig. 6D, F, and O). . . . . 16
  • Mesoma more slender and elongate (DMI2 81–87; LMI 42–53) (Fig. 10J–L); head narrower and more elongate (CI 78–80) (Fig. 6J–L). . . . . 18

16

return to couplet #15

  • Propodeum dentate, teeth well-developed (Fig. 9O); lateral propodeum with smooth, unsculptured patch dorsad propodeal spiracle (Fig. 9O); abdominal sternite 3 with strongly developed, narrow median ridge, sternite squared in profile (12O); frontal lamella thick and platelike (Fig. 6O), in profile rhomboid with three clearly demarcated faces, lacking basal fenestra (Fig. 7O). [Ivory Coast]. . . . . Discothyrea penthos
D penthos hal.jpg
  • Propodeum angulate but without differentiated teeth (Fig. 9D and F); lateral mesosoma similarly sculptured over entire surface, without distinct smooth patch on propodeum (Fig. 9D and F); abdominal sternite 3 without a median ridge or ridge broad and rounded, sternite sloping to round in profile (12D, F); frontal lamella narrow (Fig. 6D and F), not rhomboid in profile, usually with well-defined basal fenestra (Fig. 7D and F) . . . . . 17

17

return to couplet #16

  • Petiolar outline in anterior view strongly pentagonal with dorsal faces well-defined and very tall triangular peak (Fig. 30M, N); eye absent to small (OI 0–4) (Fig. 7F); AT4 longer than AT3 (ASI 117–128) (Fig. 12F); petiole thicker, less strongly attenuated (DPeI 233–286; LPeI 243–314). [Kenya, Rwanda, Uganda, Democratic Republic of Congo]. . . . . Discothyrea damato
D damato hal.jpg
  • Petiolar outline in anterior view weakly pentagonal, dorsal faces poorly defined and with low, rounded peak (Fig. 26M, N); eye present, relatively large (OI 5–9) (Fig. 7D); AT4 somewhat shorter than or subequal to AT3 (ASI 85–103) (Fig. 12D); petiole thinner, more strongly attenuated (DPeI 300–500; LPeI 286–500). [Kenya, Mozambique, Rwanda, Tanzania, Uganda]. . . . . Discothyrea athene
D athene hal.jpg

18

return to couplet #15

  • Anterolateral corners of gena rounded, not sharply angulate (Fig. 6J); abdominal sternite 3 without narrow median ridge, sternite sloping in profile with poorly-defined anterior face (Fig. 12J); petiolar outline in anterior view roughly hexagonal, dorsal face flat (Fig. 38M and N). [Tanzania]. . . . . Discothyrea hawkesi
D hawkesi hal.jpg
  • Anterolateral corners of gena sharply angulate (Fig. 6K and L); abdominal sternite 3 with narrow median ridge, sternite truncate to squared in profile with clearly defined anterior face (Fig. 12K and L); petiolar outline in anterior view roughly pentagonal, dorsally peaked (Figs. 40M, N, and 42M, N). . . . . 19

19

return to couplet #18

  • Mesosomal profile more robust (LMI 53), dorsum convex, propodeal denticles larger, propodeal declivity more strongly concave (Fig. 9L); legs longer (HFI 65) and very slender, first mesotarsomere elongate, longer than tarsomeres II–IV taken together; antennal scape longer (SI 58). [Zimbabwe]. . . . . Discothyrea maia
D maia hal.jpg
  • Mesosomal profile more gracile (LMI 42), dorsum sloping posteriorly but not convex, propodeal denticles smaller, propodeal declivity more shallowly concave (Fig. 9K); legs shorter (HFI 51) and not exceptionally slender, first mesotarsomere short, about as long as tarsomeres II–IV taken together; antennal scape shorter (SI 51). [Tanzania]. . . . . Discothyrea kalypso
D kalypso hal.jpg