Discothyrea mixta Brown, 1958a: 343
D. mixta
Revision of the Highly Specialized Ant Genus Discothyrea (Hymenoptera: Formicidae) in the Afrotropics with X-Ray Microtomography and 3 D Cybertaxonomy
Hita-Garcia, Francisco
Lieberman, Ziv
Audisio, Tracy L.
Liu, Cong
Economo, Evan P.
Insect Systematics and Diversity
2019
2019-11-14
5
1
84
6CZPZ
Brown, 1958
Brown
1958
[818,1169,1631,1654]
Insecta
Formicidae
Discothyrea
Animalia
Hymenoptera
17
18
Arthropoda
species
mixta
( Figs. 2A, 4A, 5A–D, 6A, 7A, 8A, 9A, 10A, 11A, 12A, 14A, 15A, 15F, 15G, 17B, 17D, 17G, 18, 19; Supp Video S1 [online only])
Discothyrea mixta Brown, 1958a: 343.
Type Material HOLOTYPE,pinned worker, LIBERIA, Bolahun ( L. Bequaert) ( MCZ: MCZ_ Holotype_29872) [examined]. PARATYPES,three pinned workers with same data as holotype ( MCZ: MCZ_ Paratype_29872; MHNG: CASENT0911150; USNM) [examined except USNM] Fig. 14.Diagnostic plate showing differences in body pilosity. (A) D. mixta(CASENT0235473),(B) D. oculata(CASENT0235467),(C) D. aisnetu(CASENT0235475), (D) D.athene(CASENT0235476),(E) D.chimera(CASENT0235471),(F) D.damato(CASENT0247362),(G) D.dryad(CASENT0247371),(H) D.gaia(CASENT0247040), (I) D. gryphon(CASENT0247367), (J) D. hawkesi(CASENT0235470), (K) D. kalypso(CASENT0235468), (L) D. maia(CASENT0790541), (M) D. michelae(CASENT0235469), (N) D. patrizii(CASENT0235472), (O) D. penthos(CASENT0247383), (P) D. poweri(SAM-ENT-0011509), (Q) D. schulzei(CASENT0247370), (R) D. traegaordhi(CASENT0790122), (S) D. venus(CASENT0247017), (T) D. wakanda(CASENT0790326).With the exception of F, L, R,T, all other images are from https://www.antweb.org—photographers Michele Esposito and Will Ericson. Virtual dataset.Volumetric raw data (in DICOM format), 3D rotation video, still images of surface volume rendering, and 3D surface (in PLY format) of a nontype specimen (CASENT0285473) 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.3qm4183) and can be freely accessed as virtual representation of the species. In addition to the data at Dryad, we also provide a freely accessible 3D surface model at Sketchfab (Model 1). Nontype Material ANGOLA: Dundo, R. Mussungue, [ −7.3697, 20.813], ca. 630 m, gallery forest, 18.XII.1963( Luna-Carvalho); Dundo, R. Kahingo, [−7.39, 20.51], ca. 650 m, gallery forest, 20.VI.1964( Mwaoka); Route Dundo-Saurimokm 39, 23.XI.1963( Luna-Carvalho); Salazar, [−9.3, 14.916667], ca. 700 m, forest, 9.III.1972( P.M. Hammond); CAMEROON: Abona Mbana, 28.XI.1988( A. Dejean); Ebodjie, [2.63, 9.88], ca. 70 m, 28.X.1991( A. Dejean); Nkoemvon, [ 2.7517, 11.0814], ca. 630 m, 28.IX.1980( D. Jackson); Mbalmayo, [ 3.4597, 11.4714], ca. 600 m, XI.1993( N. Stork); South, Pan Pan, 1.IV.1990( A. Dejean); Ottotomo, [3.65, 11.3167], ca. 750 m, 12.IX.1988( A. Dejean); DEMOCRATIC REPUBLIC OF CONGO: Epulu, −1.38333, 28.58333, 750 m, 1.XI.1995( S.D. Torti); North Kivu, Kivu, Lubero Territory, Rte. Kimbulu, ruis. Kitagoha, [ -0.05311, 29.22183], 1760 m, tamisage de terreau, IV.1954( R.P.M.J. Celis); North Kivu, Massif Ruwenzori, Mt. Ngulingo, prés Nyamgaleke, [ 0.498, 29.883], 2500 m, ex P. N.A., 13.I.1954( H. Synave); GHANA: Ashanti, Ofinso, [6.93, −1.65], ca. 230 m, cocoa plantation, 2.XI.1992( R. Belshaw); Aiyaola River Forest Reserve, [ 6.1510, −0.945], ca. 210 m, primary forest, 1.X.1992( R. Belshaw); Atewa Forest Reserve, near Kibi, [ 6.1747, −0.5861], ca. 400 m, primary forest, 26.II.1992( R. Belshaw); Kibi, 23.III.1970( D. Leston); Sui River Forest Reserve, [ 6.129, −2.731], ca. 220 m, primary forest, 6.X.1992( R. Belshaw); IVORY COAST: Abidjan, Banco Forest, [ 5.38694, −4.05275], ca. 20 m, I.1963( W.L. Brown); Abidjan, Banco National Park, [ 5.38694, −4.05275], ca. 20 m, primary forest, 3.III.1977( I. Löbl); Tai Forest, [5.75, −7.12], ca. 250 m, 14.V.1976( T. Diomande); Anyama, Teke Forest, [ 5.55194, −4.01111], ca. 80 m, 15.II.1974( T. Diomande); KENYA: Western Province, Kakamega Forest, Buyangu Nature Reserve, Buyangu Hill, 1570 m, 0.343, 34.863, 14.III.2002( R.R. Snelling); Western Province, Kakamega Forest, Buyangu Nature Reservenear Salazar Circuit, secondary rainforest, 0.33, 34.87, 1500 m, 21.IV.2001( R.R. Snelling& A. Espira); Western Province, Kakamega Forest, Mukangu Trail, 0.35328, 34.85886, 1623 m, primary rainforest, VII.2007( F. Hita Garcia); Western Province, Kakamega Forest, Salazar, 0.32667, 34.87083, 1650 m, primary rainforest, 21.VI.2007( M. Peters); MOZAMBIQUE: Sofala, Gorongosa National Park, Camp#1, −18.61865, 34.80866, 216 m, small forest, 18.IV.2013( L.E. Alonso); RWANDA: Kayove, -[ 1.876, 29.357], 2100 m, 12.VIII.1973( P. Werner); Rangiro, [ 2.39361, 29.18278], 1800 m, IX.1976( P. Werner); SOUTH AFRICA: KwaZulu-Natal, Ukilinga Research Farm, 10 kmSE of Pietermaritzburg, −29.6666, 30.4, 840 m, grassland, 31.XII.1991( B. Chambers); TANZANIA: Iringa, Kilolo, Ndundulu Forest Reserve, −7.78912, 36.48539, 1567 mprimary forest, 23.–26.X.2007( P. Hawkes, M. Bhoke& U. Richard); Lindi, Lindi, Ndimba Forest Reserve, −9.62695, 39.62964, 138 m, 25.–28.II.2008( P. Hawkes, Y. Mlacha& F. Ninga); Mkomazi Game Reserve, Kinondo Forest, −3.91667, 37.76667, 1270 m, montane forest, 9.V.1996( H.G. Robertson); Pwani, Mafia, Mlola Forest, Mafia Island, −7.89576, 39.82842, 20 m, primary forest, 9.–13.III.2008( P. Hawkes, Y. Mlacha& F. Ninga); South Pare Forest, −4.13056, 37.88389, 1650 m, montane forest, 29.XI.1995( H.G. Robertson); Tanga, Kilindi, Kilindi Forest Reserve, −5.57934, 37.57971, 1000 m, primary forest, 27.–30.VIII.2005( P. Hawkes, J. Makwati& R. Mtana); UGANDA: Kabarole, Kanyawara, Kibale National Park, 0.56427, 30.35876, 1510 m, montane wet forest, ex sifted leaf litter, collection code JTL7864-s, 8.VIII.2012( J. Longino); Kabarole, Kanyawara, Kibale National Park, 0.55906, 30.35954, 1510 m, montane wet forest, nocturnal foragers, 11.VIII.2012( J. Longino); Kabarole, Kanyawara, Kibale National Park, 0.55878, 30.35998, 1520 m, montane wet forest, nest in dead wood, collection code JTL7912, 13.VIII.2012( J. Longino); Kibale National Park, Kanyawara Biological Station, 0.56437, 0.56437, 1510 m, rainforest, 16.VIII.2012( G. Fischer).
Diagnosis Discothyrea mixtadiffers from D. oculataby the following combination of characters: smaller species (WL 0.59–0.72); broader head (CI 88–94); smaller eyes (OI 5–9); propodeum strongly angulate to denticulate; declivitious face of propodeum without costae or rugae; propodeum dorsally and laterally finely marginate; shorter legs (HFI 62–68); AT4 roughly sculptured, striate to punctate; scrobal area alveolate to punctate posterolaterally, becoming striulate to strigulate medially.
Worker Measurements and Indices ( n = 10) EL 0.04–0.07; HL 0.63–0.75; HW 0.57–0.68; SL 0.40–0.50; PH0.31–0.40; PW 0.43–0.53; DML 0.35–0.50; PrH 0.39–0.50; WL 0.59–0.72; HFL 0.38–0.49; PeL 0.10–0.13; PeW 0.30–0.33; PeH 0.28–0.35; LT3 0.54–0.79; LT4 0.27–0.41; OI 5–9; CI 88–94; SI 64–69; LMI 51–56; DMI 68–75; DMI2 107–121; ASI 46–58; HFI 62–68; DPeI 250–313; LPeI 240–313. Worker Description Headvery broad (CI 88–94), posterior head margin strongly convex, evenly curving into sides, posterodorsal corners of head indistinct; in frontal view sides of head convex, slightly concave between eye and anterolateral corner of gena; eyes small but well developed, setose (OI 5–9), comprising around ten small ommatidia; ommatidia globose, silvery, eyes protruding from head; eyes situated laterally 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 fused and reduced to thin, translucent septum between antennal sockets; posterolateral portion of torulus flangelike; torulus reduced posteromedially, thus confluent with deep, exposed antennal acetabulum; scrobe mostly strigulate, becoming punctate closer to eyes, merging with alveolate sculpture of head at scrobal margin; medial clypeus rectangular, short, anterior margin transverse, bearing very dense layer of appressed to decumbent white pilosity; sides of medial clypeus subparallel laterad antennal sockets. Antennawith moderately long scape (64–69), scape somewhat expanded apically, slightly bent; pedicel a short cylinder, broader than long; true antennomere count eleven; apparent antennomere count nine to eleven; flagellomeres basad apical club highly compressed, taken together approximately as long as apical club. Ventral headsurface with two low, somewhat indistinct rounded tumuli situated laterally, slightly posterad midline (in profile); postoccipital ridge with well-developed anteromedial carina, extending about a onethird of the way between occipital foramen and posteromedial extent of hypostoma; medial region of hypostoma semicircular to a low triangle, apex somewhat rounded, hypostomal arms somewhat narrowed, arms expanded slightly apicolaterally; palpal formula not examined. Mandibleedentate; basal angle rounded; with blunt prebasal angle; ectal face with longitudinal carina extending from prebasal angle to apex, carina becoming confluent with masticatory margin apically, leaving long comma-shaped, depressed, smooth medial region on masticatory margin. Fig. 15.Antennal anatomy showing flagellar fusion in Discothyrea. (A) D. mixta(CASENT0285473)—light microscopy, (B) D. traegaordhi(CASENT0790122) —light microscopy, (C) D. traegaordhi(CASENT0790122)—equivalent view to 15B but performed with surface volume rendering, (D) Zasphinctus sarowiwai Hita Garcia, 2017(CASENT0764654)—sagittal section of surface volume rendering, (E) D. traegaordhi(CASENT0790122)—sagittal section of surface volume rendering, (F) D. mixta(CASENT0790542)—surface volume rendering showing each antennomere in different color, (G) D. mixta(CASENT0790542)—equivalent view to 15F but sagittal section, (H) D. dryad(CASENT0247374)—sagittal section of surface volume rendering showing each antennomere in different color, (I) D. gryphon(CASENT0790103),sagittal section of surface volume rendering showing each antennomere in different color. Fig. 16.Shaded surface display of transparent volume renderings showing internal and external flagellar subsegmentation. (A) Discothyrea oculata(CASENT0195471), (B) Proceratium deelemaniPerrault, 1981(CASENT0790842), (C) Brachyponera sennaarensis(Mayr, 1862)(CASENT0790837), (D) Solenopsis invictaBuren, 1972(OKENT0011209). Mesosomarobust, evenly convex, pronotum scarcely higher than propodeum; in dorsal view mesosoma relatively broad and stout (DMI 68–75; DMI2 107–121) and distinctly narrowed posteriorly, pronotum distinctly wider than propodeum; pronotal humeri obliquely rounded; posterior propodeal margin straight; posterodorsal corners of propodeum strongly angulate to denticulate, angles subtended and medially joined by narrow carinulae, thus propodeum laterally and dorsally marginate; in posterior view, carinulae forming two arches, shaped like an inverted lowercase omega, medially joining as unpaired carina traversing declivitous face; declivitous face of propodeum distinctly concave in profile and oblique posterior view; propodeal spiracle small and indistinct, directed posterolaterally; propodeal lobes very short and blunt. Legsquite long (HFI 62–68) and robust; mesotibia with short but distinct apicoventral spur. Petiolar nodethickly disciform, not attenuated dorsally, about 2.4 to 3.2 times higher than broad (LPeI 240–313); 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 2.2 to 3.2 times broader than long (DPeI 215–313); in anterior view, petiolar outline subcircular; in oblique anterodorsal view with weak median concavity; in ventral view, a narrow trapezoid, sides diverging strongly posteriorly; subpetiolar process short, lobate to subquadrate. Abdominal segment 3asymmetrically campaniform, tergite evenly convex, widest posteriorly; AS3 somewhat flat to bulging posteriorly, deepest posteriorly, with concave, mostly unsculptured anteromedial region bordered anteriorly by sharply carinate, laterally narrow prora; AT3 approximately 1.9 to 2.2 times longer than AT4 (ASI 46–58); AT4 hemidemispherical to semicylindrical, gently recurved, spiracle sometimes exposed, small but prominent; successive abdominal segments short, telescopic, often concealed. Sculptureon 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 weakest on lateral mesosoma; ventral head surface posteromedially unsculptured; scape densely punctate; declivitous face of propodeum smooth except for fine medial carina; AT4 densely punctate, punctae usually more distinct posterolaterally; mandibles with numerous piligerous punctae. Setationfairly consistent on dorsal surfaces of head, mesosoma, and petiole, a dense layer of appressed to erect white setae; gena and lateral mesosoma sometimes with sparser setation; density and length 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, fine appressed pubescence and dense dorsal layer of decumbent to erect pilosity; successive abdominal segments with dense, flocculent, erect yellowish setae; ectal face of mandible with fine, curved, appressed to decumbent setae; with row of stout, spatulate setae on mesal face of masticatory margin; legs with fairly dense but relatively fine and entirely appressed white pubescence. Colortestaceous- to luteous-orange; legs and abdominal segments III–VII often bright orange to yellowish, lighter than rest of body.
Distribution and Biology Discothyrea mixtais better represented in collections than D. oculataand most species of the traegaordhicomplex, which may suggest lifestyle differences, making them more amenable to discovery, or be indicative of truly greater abundance. The species is known from a variety of forest habitats at different elevations throughout most of the Afrotropical region ( Fig. 4A).
In foraging experiments, Dejean et al. (1999)found that D. mixtaonly accepted spiderlings and spider eggs as prey items. They rapidly consumed the spiderlings while often storing the eggs as a long-term resource. These findings are supported by unpublished observations made on a nest collection in KibaleForest, Uganda, which revealed a large number of unidentified, rounded eggs, presumably of spiders.
Comments The separation of D. mixtafrom D. oculatais 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. Something that we cannot rule out, despite considering it not very likely, is that the material here considered as D. mixtamight represent a complex of cryptic species. The observed variety (see below) is not very pronounced but the highly specialized lifestyle might constrain morphological diversity, which would hinder species recognition purely based on morphology. Future studies including molecular data from most populations of D. mixtashould revisit this question. However, on the basis of our study there is no evidence for cryptic species. Variation Discothyrea mixtavaries slightly in overall size (WL 0.59–0.72), number of ommatidia, and coarseness of sculpture. Frequently, the sculpture of the lateral mesosoma is somewhat reduced, and the propodeal carinulae can vary slightly in shape and distinctness. The length, abundance, and stature of pilosity are somewhat variable, forming a more or less distinct dorsal layer on the mesosoma and abdominal terga. Nevertheless, considering the extremely wide distribution of D. mixta, this observed intraspecific variation is not surprising and even lower than one might expect.
2451560258
MCZ
L. Bequaert
Liberia
LIBERIA
17
18
2
holotype
2451560254
MCZ, MHNG
L. Bequaert
Liberia
LIBERIA
17
18
CASENT0911150
2
paratype
2451560187
1963-11-23
1972-03-09
1963-11-23
Dundo, R & Luna-Carvalho & Mwaoka & Route Dundo-Saurimo & Salazar & P. M. Hammond
Angola
630
-7.3697
ANGOLA
55
20.813
18
19
1
2451560248
1980-09-28
1993-11
1980-09-28
A. Dejean & D. Jackson & N. Stork & South & Pan Pan & Ottotomo
Cameroon
Abona Mbana
70
19
20
3.4597
Nkoemvon
7
11.4714
Ebodjie
18
19
1
2451560171
1995-11-01
S. D. Torti
Democratic Republic of the Congo
750
-1.38333
Epulu
1
28.58333
19
20
1
2451560205
1954-04
R. P. M. J. Celis
Democratic Republic of the Congo
Lubero Territory
1760
-0.05311
Kitagoha
1
29.22183
Rte. Kimbulu
19
20
1
Nord-Kivu
2451560250
1954-01-13
N. Akkari & H. Synave
Democratic Republic of the Congo
Massif Ruwenzori
2500
0.498
Nyamgaleke
78
29.883
Mt. Ngulingo
19
20
1
Nord-Kivu
2451560200
1970-03-23
1992-11-02
1970-03-23
R. Belshaw & D. Leston
Ghana
Ofinso
230
6.129
Atewa Forest Reserve
78
-2.731
Aiyaola River Forest Reserve
19
20
1
Ashanti
2451560264
1963-01
W. L. Brown
Ivory Coast
20
5.38694
Banco Forest
1
-4.05275
19
20
1
Abidjan
2451560169
1974-02-15
1977-03-03
1974-02-15
I. Lobl & T. Diomande
Ivory Coast
Banco National Park
20
5.55194
Teke Forest
1
-4.01111
Tai Forest
19
20
1
Abidjan
2451560196
Kenya
Western Province
19
20
1
2451560164
2002-03-14
R. R. Snelling
Kenya
Forest
1570
0.343
Buyangu Hill
78
34.863
Buyangu Nature Reserve
19
20
1
Kakamega
2451560255
2001-04-21
R. R. Snelling & A. Espira
Kenya
Forest
1500
Salazar Circuit
Buyangu Nature Reserve
19
20
1
Kakamega
2451560176
2007-07
F. Hita Garcia
Kenya
Forest
1623
0.35328
Western Province
1
34.85886
Mukangu Trail
19
20
1
Kakamega
2451560259
2007-06-21
M. Peters
Kenya
1650
0.32667
Salazar
1
34.87083
Forest
19
20
1
Kakamega
2451560228
2013-04-18
L. E. Alonso
Mozambique
216
-18.61865
Camp
1
34.80866
Gorongosa National Park
19
20
1
Sofala
2451560244
1973-08-12
1976-09
1973-08-12
Werner & P. Werner
Rwanda
2100
2.39361
Rangiro
1
29.18278
Kayove
19
20
1
2451560233
1991-12-31
B. Chambers
South Africa
840
Ukilinga Research Farm
19
20
1
KwaZulu-Natal
2451560235
2007-10-23
2007-10-26
2007-10-23
P. Hawkes & M. Bhoke & Richard
Tanzania
1567
-7.78912
Ndundulu Forest Reserve
1
36.48539
Kilolo
19
20
1
Iringa
2451560267
1996-05-09
2008-02-28
1996-05-09
P. Hawkes & Y. Mlacha & F. Ninga & H. G. Robertson
Tanzania
Ndimba Forest Reserve
138
-3.91667
Kinondo Forest
1
37.76667
Mkomazi Game Reserve
19
20
1
Lindi
2451560276
1995-11-29
2008-03-13
1995-11-29
P. Hawkes & Y. Mlacha & F. Ninga & H. G. Robertson
Tanzania
Mafia
20
-4.13056
Mafia Island
1
37.88389
Mlola Forest
19
20
1
Pwani
2451560269
2005-08-27
2005-08-30
2005-08-27
P. Hawkes & J. Makwati & Mtana
Tanzania
1000
-5.57934
Kilindi Forest Reserve
1
37.57971
Kilindi
19
20
1
Tanga
2451560181
[1061,1372,413,433]
Kanyawara
Uganda
Kabarole
19
20
1
Kabarole
2451560221
2012-08-08
J. Longino
Uganda
1510
0.56427
National Park
1
30.35876
19
20
1
Kibale
2451560202
[818,1024,501,521]
Kanyawara
Uganda
Kabarole
19
20
1
Kabarole
2451560219
2012-08-11
J. Longino
Uganda
1510
0.55906
National Park
1
30.35954
19
20
1
Kibale
2451560257
[919,1126,560,580]
Kanyawara
Uganda
Kabarole
19
20
1
Kabarole
2451560185
2012-08-13
J. Longino
Uganda
1520
0.55878
National Park
1
30.35998
19
20
1
Kibale
2451560242
2012-08-16
G. Fischer
Uganda
1510
0.56437
Kanyawara Biological Station
1
0.56437
National Park
19
20
1
Kibale