Discothyrea dryad Hita Garcia & Lieberman, 2019

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, pp. 1-84 : 40-43

Discothyrea dryad Hita Garcia & Lieberman sp. n.

( Figs. 4G , 6G , 7G , 8G , 9G , 10G , 11G , 12G , 13D , 14G , 15H , 31 , 32 ; Supp. Video S7 [online only])

Type Material

HOLOTYPE, pinned worker, KENYA, Rift Valley Province , Mau Forest , between Mau summit and Kedowa, [-0.17, 35.59], ca. 2200 to 2400 m, collection code ANTC37525, litter sample, 7.XI.1974 (V. Mahnert) ( BMNH: CASENT0247374 ) . Paratypes, two pinned workers with same data as holotype ( MCZC: MCZ-ENT00593561; SAMC: CASENT0247373 ) .

Cybertype. Volumetric raw data (in DICOM format), 3D rotation video, still images of surface volume rendering, and 3D surface (in PLY format) of the physical holotype (CASENT0247374) 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 type. In addition to the cybertype data at Dryad, we also provide a freely accessible 3D surface model of the holotype at Sketchfab (Model 7).

Nontype Material

KENYA: Eastern Province, Embu, Irangi Forest Station , −0.3475, 37.485, 2000 m, 11.V.1977 (V. Mahnert & J.L. Perret); Eastern Province , Embu, Kirimiri Forest , W. of Runyenje , −0.41861, 37.54278, ca. 1550 m, 3.X.1977 (V. Mahnert & J.L. Perret); Rift Valley Province , Nadarua County, Mt. Aberdares National Park , [−0.38, 36.699], 2300 m, sifted leaf litter, 25.XI.1974 (V. Mahnert) .

Diagnosis

The following character combination distinguishes Discothyrea dryad from the remainder of the complex: larger species (WL 0.56–0.60); dense layer of standing pilosity present on dorsal surfaces of body; mesosoma thick but elongate (DMI2 87–91), in dorsal view clearly tapering posteriorly; in profile frontal lamella with anterodorsal corner angulate, with prominent, elongate elliptic basal fenestra; masticatory margin of mandible edentate; anterolateral corner of gena not sharply angled and not denticulate/dentate; Model 7. 3D surface model of D. dryad sp. n. holotype (CASENT0247374). An interactive version of this model is available in the HTML version of this article online and at https://sketchfab.com/3d-models/33779d9ea2884e729cc 6bddcb0375f5e.

mesosomal outline weakly to moderately convex; propodeum angulate to weakly dentate; mesotibia without apicoventral spur; AT4 around 1.2 to 1.3 times longer than AT3 (ASI 122–133); subpetiolar process shorter, blunt or rounded, not projecting anteroventrally; abdominal sternite 3 rounded and without any projecting lobe; anterior clypeal margin bearing only short curved setae.

Worker Measurements and Indices (n = 5)

EL 0.01–0.02; HL 0.52–0.57; HW 0.42–0.45; SL 0.29–0.32; PH 0.33–0.35; PW 0.33–0.34; DML 0.36–0.39; PrH 0.33–0.35; WL 0.56–0.60; HFL 0.31–0.36; PeL 0.08–0.09; PeW 0.19–0.21; PeH 0.22–0.23; LT3 0.31–0.34; LT4 0.44–0.46; OI 2–4; CI 79–81; SI 55–56; LMI 45–49; DMI 56–58; DMI2 87–91; ASI 122–133; HFI 54–60; DPeI 222–250; LPeI 244–288.

Worker Description

Head subrectangular, clearly longer than broad, (CI 79–81), posterior head margin more or less straight; posterodorsal corners of head rounded; in frontal view, sides of head slightly convex; eyes minute (OI 2–4), a simple pigmented spot or with a few tiny ommatidia, situated slightly anterad one-third of the way between anterolateral corner of gena and posterior head margin, sometimes just visible in frontal view; frontal lamella short, dentiform in profile, apex acute; lamella with well-defined, elliptical translucent basal fenestra; medial clypeus gently convex, lateral clypeus curving gently between antennal sockets and anterolateral corners of head, bearing short curved setae. Antenna with moderately long scape (SI 55–56), scape moderately incrassate, gently bent; pedicel campaniform, slightly longer than broad; true antennomere count nine; apparent antennomere count nine to eleven, flagellomeres basad apical club highly compressed, taken together only about as long as apical club. Ventral head with weakly developed postoccipital ridge without anteromedial carina; medial region of hypostoma strongly triangular, arms narrowed, slightly spatulate apicolaterally; palpal formula not examined. Mandible edentate except for relatively large, curved prebasal denticle; an indistinct preapical swelling sometimes present; ectal face with longtudinal carina confluent with masticatory margin for most of its length, leaving just preapical denticle offset in smooth depressed region.

Mesosoma weakly to moderately convex, pronotum approximately at same level as propodeum; in dorsal view mesosoma moderately thick (DMI 56–58; DMI2 87–91) and narrowed posteriorly, pronotum wider than propodeum; pronotal humeri rounded; posterior propodeal margin concave; posterodorsal corners of propodeum denticulate to weakly dentate; declivitous face of propodeum distinctly concave in profile and oblique posterior view; propodeal spiracle small, inconspicuous, directed posterolaterally; propodeal lobes dorsoventrally broad but anteroposteriorly short, blunt-flangelike.

Legs short to intermediate in length (HFI 54–60); mesotibia without apicoventral spur; with small but distinct seta inserted in apical pit; mesobasitarsus relatively short, slightly longer than tarsomeres II–IV taken together.

Petiolar node not strongly attenuated dorsally, though peaked in profile, about 2.5 to 2.9 times as high as long (LPeI 244–288); in profile anterior face of node posterodorsally sloping, apex peaked, posterior face sloping posteroventrally; in dorsal view, petiole rectangular, sides subparallel to somewhat convex, about 2.2 to 2.5 times as broad as long (DPeI 222–250); in anterior view, petiolar outline roughly pentagonal, angles rounded but faces well defined; in oblique anterior view, anterior face flat; in ventral view, broadly rectangular, sides weakly diverging posteriorly; subpetiolar process relatively short, lobate to triangular with rounded apex; petiolar spiracles very large, elliptical to roughly reniform in ventral view.

Abdominal segment 3 roughly campaniform, tergite prolonged anteriorly past anterior sternal margin; sternite convex in profile; AS 3 with thick ridge broadening to lobe at about sternite’s midline; AS 3 without carinate prora, but still with anterior face distinctly depressed and anterior margin of ventral face concave in ventral view; AT4 around 1.2 to 1.3 times longer than AT3 (ASI 122–133); AT4 almost perfectly hemidemispherical; AS 4 with well-developed anterior lip, overlapping most of the width of AS 3, anterior margin straight to very weakly sinuate in ventral view; successive abdominal segments short, telescopic, often concealed.

Sculpture on head, mesosoma, petiole, and abdominal segment 3 regularly foveolate-reticulate, usually somewhat coarser on head than mesosoma; ventral head AT3 sometimes more sparsely punctate; sculpture becoming weak or absent posterad antennal sockets; ventral head surface punctate to finely punctulate-reticulate; mandible roughly sculptured with piligerous punctulae; AT4 distinctly smoother and shinier than AT3, with abundant but fine piligerous punctulae, becoming finely rugulose posteriorly.

Setation on head mostly fine, appressed, white pubescence; a few short erect hairs sometimes present on head; mesosomal, petiolar, and abdominal dorsa with fairly abundant standing pilosity, mostly subdecumbent or suberect, with scattered erect setae, in addition to appressed pubescence, longer and more abundant than on head; appressed pubescence on lateral mesosoma, sides of AT3, and abdominal sternite 3 very dilute and inconspicuous, that on AT4 longer and evenly distributed over entire tergite; successive abdominal segments with standing pilosity not significantly longer than that on AT4 though somewhat more conspicuous due to reduced sculpture; scape and legs with evenly distributed appressed pubescence; ectal face of mandible with relatively long, curved, appressed to decumbent setae; masticatory margin with row of straight setae.

Color dull testaceous orange, head and gastral dorsa sometimes lightly infuscated.

Etymology

In Greek mythology, the dryads were forest spirits that personified and protected their habitat. The species is named in recognition of the patchy and threatened status of the forests from which most Afrotropical Discothyrea originate.The specific epithet is given as an appositive noun.

Distribution and Biology

The new species is known from three Afromontane forest locations in Kenya ( Fig. 4G ), at elevations from around 1500 to 2300 m, where it seems to live in leaf litter.

Comments

Discothyrea dryad bears some similarity to D. athene , D. damato , D. wakanda , and D. schulzei based on the conspicuous elliptical basal fenestra on the frontal lamella and the absence of a mesotibial spur. Notably it differs from these species in the shape of the frontal lamella and the mesosoma. In D. dryad , the lamella has a distinctively angulate profile, while it is rounded in the others. The mesosoma of D. dryad is more elongate (LMI 51–57; DMI 56–58; DMI2 87–91 versus LMI 48–57; DMI 58–66; DMI2 102–103) and in dorsal view distinctly narrows posteriorly. The presence of standing pilosity on the mesosomal and abdominal terga separates D. dryad , D. wakanda , and D. schulzei from D. damato . Additionally, D. dryad is larger than D. schulzei (WL 0.56–0.60 vs. 0.47–0.56, respectively) and smaller than D. wakanda (WL 0.59–0.65). Nevertheless, based on their character sets and geographical distribution, these three species appear to be closely related.

Variation

Discothyrea dryad varies mostly in the number and arrangement of fully erect setae among the standing pilosity. This character is prone to distortion from the media and conditions of collection and preservation.

Figures

Fig. 4. Maps showing the known distribution ranges of Afrotropical Discothyrea species.

Fig. 6. Diagnostic plate showing still images from surface volume renderings of the head in full-face view (the remainder of the body virtually removed). All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation.Specimen codes are given inTable 1.

Fig. 7. Diagnostic plate showing still images from surface volume renderings of the head in profile (the remainder of the body virtually removed).All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation. Specimen codes are given inTable 1.

Fig. 8. Diagnostic plate showing still images from surface volume renderings of the right mandible in dorsal view (the remainder of the body virtually removed).All Afrotropical species are shown,species names are embedded in each particular image for better comparison and orientation.Specimen codes are given inTable 1.

Fig. 9. Diagnostic plate showing still images from surface volume renderings of the mesosoma in profile (the remainder of the body virtually removed). All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation.Specimen codes are given inTable 1.

Fig. 10. Diagnostic plate showing still images from surface volume renderings of the body in dorsal view with focus on mesosoma.All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation. Specimen codes are given inTable 1.

Fig. 11. Diagnostic plate showing still images from surface volume renderings of the posterior propodeum in posterior view (the remainder of the body virtually removed). All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation. Specimen codes are given inTable 1.

Fig. 12. Diagnostic plate showing still images from surface volume renderings of the petiole and gaster in profile (the remainder of the body virtually removed).All Afrotropical species are shown, species names are embedded in each particular image for better comparison and orientation.Specimen codes are given inTable 1.

Fig. 13. Diagnostic plate showing still images from surface volume renderings of mesotibiae and mesotarsi with mesotibial apicoventral spur, if present, colorized in green. (A) D. gaia, (B) D. poweri, (C) D. traegaordhi, (D) D. dryad, (E) D. maia, (F) D. wakanda.

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.

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. 31. Stacked digital color images of D. dryad sp. n. (CASENT0247371 - from https://www.antweb.org, photographer Michele Esposito). (A) body in profile, (B) body in dorsal view, (C) head in full-face view.

Fig. 32. Still images from shaded surface display volume renderings of D. dryad sp. n. holotype (CASENT0247374) showing virtually segmented body parts. (A) Body in dorsal view, (B) body in profile, (C) head in full-face view, (D) head in dorsal view, (E) head in anterodorsal view, (F) head in anterior view, (G) head in profile, (H) head in ventral view, (I) posterior propodeum in posterior view, (J) petiole in profile, (K) petiole and gaster in profile, (L) petiole in dorsal view, (M) petiole in anterior view, (N) petiole oblique anterior view, (O) gaster in dorsal view, (P) petiole in ventral view, (Q) abdominal sternite 3 in ventral view, (R) mesotibia and mesotarsus in anterior view.