Discothyrea venus Hita-Garcia, Lieberman, Audisio, Liu, and Economo 2019
- Dataset
- Revision of the Highly Specialized Ant Genus Discothyrea (Hymenoptera: Formicidae) in the Afrotropics with X-Ray Microtomography and 3 D Cybertaxonomy
- Rank
- SPECIES
- Published in
- Hita-Garcia, Francisco, Lieberman, Ziv, Audisio, Tracy L., Liu, Cong, Economo, Evan P. (2019): Revision of the Highly Specialized Ant Genus Discothyrea (Hymenoptera: Formicidae) in the Afrotropics with X-Ray Microtomography and 3 D Cybertaxonomy. Insect Systematics and Diversity 5: 1-84, DOI: 10.1093/isd/ixz015
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Insecta
- order
- Hymenoptera
- family
- Formicidae
- genus
- Discothyrea
- species
- Discothyrea venus
description
(Figs. 2 C, 4 S, 6 S, 7 S, 8 S, 9 S, 10 S, 11 S, 12 S, 14 S, 56, 57; Supp. Video S 19 [online only])
description
Worker Measurements and Indices (n = 12) EL 0.00 – 0.01; HL 0.41 – 0.48; HW 0.33 – 0.40; SL 0.20 – 0.26; PH 0.20 – 0.25; PW 0.26 – 0.32; DML 0.24 – 0.30; PrH 0.25 – 0.29; WL 0.39 – 0.47; HFL 0.25 – 0.33; PeL 0.05 – 0.07; PeW 0.15 – 0.19; PeH 0.14 – 0.18; LT 3 0.19 – 0.24; LT 4 0.33 – 0.39; OI 0 – 3; CI 80 – 84; SI 48 – 55; LMI 51 – 55; DMI 62 – 69; DMI 2 95 – 107; ASI 158 – 183; HFI 63 – 74; DPeI 250 – 321; LPeI 233 – 300. Worker Description Head longer than broad (CI 80 – 84), posterior head margin slightly convex overall, with very weak impression medially; posterodorsal corners of head quite broadly rounded; in frontal view, sides of head convex; eyes absent or extremely minute (OI 0 – 3), a tiny pigmented spot situated about a third of the way between anterolateral corner of gena and posterior head margin, not visible in frontal view; frontal lamella lobate in profile, apex blunt to rounded; lamella with well-defined translucent basal fenestra; medial clypeus broad, convex, sides of medial clypeus subparallel laterad antennal sockets, lateral clypeus curving fairly strongly between antennal sockets and anteroalteral corners of head, entire clypeal margin bearing very short curved setae. Antenna with usually shorter scape (SI 48 – 55), scape moderately incrassate, gently bent; pedicel subglobose, width and length subequal or slightly broader than long; apparent antennomere count seven to eleven (usually seven to eight) but often not discernable and extremely difficult to count, flagellomeres basad apical club highly compressed, taken together only about as long as apical club. Ventral head with weakly sinuate preoccipital ridge with short but distinct anteromedial carina; median region of hypostoma rounded-triangular, arms distinctly narrowed, slightly spatulate apicolaterally; palpal formula not examined. Mandible edentate or with slight preapical swelling, without prebasal denticle; basal angle denticulate; ectal face with carina extending from base of basal denticle, becoming confluent with masticatory margin preapically, leaving narrow, comma-shaped depressed region. Mesosoma gently convex in profile, pronotum slightly higher than propodeum; in dorsal view, mesosoma conspicuously thick, robust and stocky (DMI 59 – 66; DMI 2 95 – 102), strongly narrowed posteriorly, pronotum much wider than propodeum; pronotal humeri rounded; posterior propodeal margin distinctly concave; posterodorsal corners of propodeum strongly angulate but lacking differentiated denticles; declivitous face of propodeum strongly concave in profile and oblique posterior view; propodeal spiracle directed posterolaterally, often relatively conspicuous due to small patch of shiny, polished sculpture offsetting spiracular opening from remainder of propodeum; propodeal lobes short, truncate. Legs relatively long (HFI 63 – 74) and slender; mesotibia without apicoventral spur; mesobasitarsus relatively short, subequal in length to tarsomeres II – IV taken together. Petiolar node moderately attenauted dorsally, about 2.3 to 3.0 times as high as long (LPeI 233 – 300); in profile, anterior face of node convex, apex peaked, posterior face sloping posteroventrally; in dorsal view, petiole subrectangular, sides diverging posteriorly, about 2.5 to 3.2 times as broad as long (DPeI 250 – 321); in anterior view, petiolar outline roughly pentagonal, edges poorly defined and angles rounded; in oblique anterior view, anterior face flat; subpetiolar process short, dentate, apex acute. Abdominal segment 3 short, broadly campaniform, widest point just anterad end of segment; sternite more or less evenly convex in profile; AS 3 without median ridge or lobe; prora finely carinulate, concave in ventral view; AT 4 around 1.6 to 1.8 times as long as AT 3 (ASI 158 – 183), AT 4 bulbous, swollen hemidemispherical, or more elongate, shaped as quarter of prolate ellipsoid; AS 4 with broad, well-developed anterior lip, overlapping most of the width of AS 3, anterior margin concave in ventral view; successive abdominal segments short, telescopic, often concealed, projecting strongly anteriorly due to size and shape of AT 4. Sculpture in general shallow and somewhat indistinct; head, dorsal mesosoma, and petiole similarly and evenly punctatereticulate, punctae often more pronounced on head than mesosoma; mandible fairly smooth except for small piligerous punctae; lateral mesosoma with punctae particularly indistinct, interspaces of punctae variably coalescent, forming weak rugulae; declivitous face of propodeum transversely substrigulate over around the ventral half; abdominal segment 3 weakly punctulate; AT 4 with even finer piligerous punctulae. Setation generally very fine and dilute, similar over all tagma and consisting entirely of short, appressed white pubescence; pubescence slightly longer on abdominal segment 3 and AT 4, slightly reduced on lateral mesosoma; ectal face of mandible with moderately long, curved, appressed to decumbent setae; masticatory margin with row of short straight setae; scape and legs with similarly short, velvety pubescence; abdominal segments 5 to 7 with standing setae, quite Model 20. 3 D surface model of D. wakanda sp. n. holotype (CASENT 0790326). An interactive version of this model is available in the HTML version of this article online and at https: // sketchfab. com / 3 d-models / 862743 aa 29 d 24113957 b 4 c 3 ca 277 d 82 a. long relative to setation on remainder of body (but rather short relative to that of segments 5 to 7 on most other Afrotropical species). Color testaceous-orange, sometimes lightly infuscated on dorsal surfaces.
diagnosis
Diagnosis The following character combination distinguishes D. venus from the remainder of the complex: masticatory margin of mandible edentate; anterolateral corner of gena not denticulate / dentate; propodeum laterally and dorsally strongly concave posteriorly; metatibae without apicoventral spur; lower portion of declivitous face of propodeum transversely substrigulate; AT 4 extremely enlarged, bulbous, and much longer than AT 3 (ASI 158 – 183).
discussion
Comments Discothyrea venus is a highly conspicuous species within the Afrotropical fauna. The character combination given in the diagnosis above discriminates it clearly from the remainder of the genus. To the best of our knowledge, the dramatically enlarged fourth abdominal tergite in particular (ASI 156 – 194) is not approximated by any other congener. Variation Considering the relatively broad distribution in West and Central Africa, it is surprising to see only very little variation. The eyes are entirely absent in some individuals, while in others they are present but minute, more like an indistinct pigmented spot. The length of the abdominal terga is somewhat variable but the fourth tergite is always significantly larger than the third. The development of sculpturation, particularly on the lateral mesosoma, is somewhat variable between individuals, with some possessing more pronounced punctae, but overall is similarly shallow and indistinct.
distribution
Distribution and Biology This species is patchily but widely distributed throughout Equatorial Africa (Fig. 4 S). Currently, it is known from many localities in Ivory Coast and Ghana, some in Cameroon and Angola, and one in Western Uganda. With the exception of Kibale Forest in Uganda, which is situated at an elevation of around 1500 m, all other known localities are lowland rainforests ranging from 30 m to 650 m elevation. The highly disjunct distribution is likely due to a sampling bias, and we think it is highly probable that D. venus will also be found in more or even all countries of the Congo Basin.
etymology
Etymology Venus was the Roman goddess of love, beauty, and prosperity. Among her local epithets was Venus Kallipygos, ‘ she of the beautiful buttocks’; the species is named in reference to the hypertrophied fourth abdominal tergite. The specific epithet is given as an appositive noun.
materials_examined
Type Material HOLOTYPES, pinned worker, IVORY COAST, Abidjan, Banco National Park, [5.38694, − 4.05275], ca. 20 m, primary forest, dead trunk, collection code ANTC 42125, 3. II. 1977 (I. Löbl) (BMNH: CASENT 0790116). PARATYPES, six workers with same data as holotype (BMNH: CASENT 0790115; CASC: CASENT 0247017; HLMD: HLMD-Hym- 2397; MCZC: MCZ-ENT 00593559; MHNG: CASENT 0247013; SAMC: CASENT 0247016). Cybertype. Volumetric raw data (in DICOM format), 3 D rotation video, still images of surface volume rendering, and 3 D surface (in PLY format) of the physical holotype (CASENT 0790116) in addition to stacked digital color images illustrating head in full-face view, profile and dorsal views of the body. The data are deposited at Dryad (Hita Garcia et al. 2019, http: // doi. org / 10.5061 / dryad. 3 qm 4183) and can be freely accessed as virtual representation of the type. In addition to the cybertype data at Dryad, we also provide a freely accessible 3 D surface model of the holotype at Sketchfab (Model 19). Nontype Material ANGOLA: R. Kahingo, [− 7.39, 20.51], ca. 650 m, gallery forest, 20. VI. 1964 (Mwaoke); R. Mussungue, mouth, Route Turisme, [− 7.3697, 20.813], ca. 630 m, gallery forest, 8. XI. 1963 (L. Carvalho); CAMEROON: Ebolowa, [2.92, 11.13], 640 m, 22. VIII. 1940 (A. I. Good); Nkoemvon, [2.7517, 11.0814], ca. 630 m, 5. I. 1980 (D. Jackson); GHANA: Aiyaola Forest Reserve, Kade, [6.1510, − 0.945], ca. 210 m, primary forest, 6. X. 1992 (R. Belshaw); Ashanti, Ofinso, [6.93, − 1.65], ca. 230 m, cocoa plantation, 2. XI. 1992 (R. Belshaw); Atewa Forest Reserve, nr. Kibi, [6.1747, − 0.5861], ca. 400 m, 26. II. 1992 (R. Belshaw); Eastern, Bunso, nr. Tafo, [6.28761, − 0.46948], ca. 240 m, primary forest, 6. XI. 1992 (R. Belshaw); IVORY COAST: Abidjan, Banco National Park, [5.38694, − 4.05275], ca. 20 m, primary forest, 3. II. 1977 (I. Löbl); Adiopodoume, [5.335, − 4.131], ca. 30 m, 31. X. 1980 (V. Mahnert & J. L. Perret); Abidjan, Banco Forest, collection code A 50, [5.39, − 4.05], 79 m, 11. I. 1963 (W. L. Brown); Agboville, Yapo Forest, near Yapo-Gare, [5.77105, − 4.12376], ca. 80 m, 21. – 23. III. 1977 (I. Löbl); Man, ravine at foot of Mt. Tonkoui, [7.4014, − 7.5791], ca. 640 m, 9. III. 1977 (I. Löbl); Nzi Noua, N. of Ndouci, [6.03283, − 4.84893], ca. 60 m, degraded forest, 13. I. 1977 (W. L. & D. E. Brown); UGANDA: Kibale National Park, Kanyawara Biological Station, 0.56437, 30.36059, 1510 m, rainforest, 6. – 16. VIII. 2012 (G. Fischer).