Ravavy goldmani, Boudinot & Perrichot, 2022

Perrichot, Vincent, Boudinot, Brendon E., Engel, Michael S., Fls, Xu, Chunpeng, Bojarski, Błażej & Szwedo, Jacek, 2022, Ants (Hymenoptera: Formicidae) from Miocene Ethiopian amber: filling gaps in the geological record of African terrestrial biota, Zoological Journal of the Linnean Society 196, pp. 775-791 : 782-785

RAVAVY GOLDMANI BOUDINOT & PERRICHOT

SP. NOV.

( FIGS 4–5 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 693FB2F0-817E-4BD6-B2E4-5585AFC99EA2.

Type material: Holotype NIGP180512, male, housed in the Nanjing Institute of Geology and Palaeontology (NIGPAS, China); paratype IGR.ET2015/001a, male, housed in the Geological Museum of the University of Rennes (IGR, France). In Early Miocene (16–23 Mya) amber from the North Shewa Zone, Amhara region, Ethiopia.

Etymology: The specific epithet honours Mr Yale Goldman (Bloomfield, Connecticut) who kindly facilitated access to the type specimens of the new species.

Diagnosis: Because of the limited knowledge of male ants at the global scale, this diagnosis is broken into four parts in order to establish the identity of the treated specimens: identification at the subfamilial, tribal, generic and species levels.

(I) Identifiable as Dolichoderinae by the following combination: (1) clypeal condyle large, rhomboidal (see note 1 below); (2) forewing cross-vein cu-a prefurcal, i.e. joining M+Cu proximad branching point of M and Cu; (3) helcium infraaxial; (4) abdominal segment III unpetiolated, i.e. not reduced in size relative to segment IV; (5) prora absent; (6) abdominal segment IV without cinctus; (7) gonostylus dorsoventrally short relative to gonocoxite, proximally constricted and not extending proximad gonocoxite (note 2); (8) basivolsellar process present (note 3).

(II) Identifiable as Bothriomyrmecini by the following combination (note 4): (9) clypeus not extending posteriorly between toruli; (10) medial hypostomal lamina absent; (11) forewing cross-vein 2rs-m absent.

(III) Identifiable as Ravavy by the following features, all of which are unique within Bothriomyrmecini (note 5): (12) mandible unidentate, spatulate with an apical spiniform tooth (vs. mandible multidentate, strapshaped to spiniform) (note 6); (13) palp formula 6,3 (vs. 6,4 or ≤ 4,3) (note 7); (14) pterostigma situated immediately proximad forewing midlength (vs. situated distad); (15) marginal cell extremely long, somewhat more than twice the length of submarginal cell 1; (16) Rf appendix, i.e. distalmost free abscissa of R, long, somewhat shorter than pterostigma; (17) discal cell subrectangular, longer proximodistally than wide anteroposteriorly and size small; (18) petiolar node broadly convex in profile view (vs. anteroposteriorly narrow and squamiform); (19) penite apices not downcurved, but rather being produced distally as long, linear processes.

(IV) Distinguished from Ravavy miafina by the following (note 8): (20) smaller, BL ~ 2.57–2.34, WL ~ 0.43–0.46, FWL ~ 2.17–2.52 (vs. larger, BL ~3.33–4.46, WL ~ 1.30–1.67, FWL ~ 3.85–3.99); (21) head somewhat broader, CI ~ 122 (vs. narrower, CI ~112–114, although 122 in one specimen); (22) malar space relatively long, MSI ~ 6 and space distinctly longer than proximal width of mandible in lateral view (vs. relatively short, MSI ~ 28–32 and distinctly shorter than proximal mandibular width); (23) eye relatively long, OI ~ 40–39 (vs. eye relatively short, OI ~ 14–18); (24) ocelli relatively small, OCI ~ 38 (vs. 44–62); (25) antennomere III but not IV slightly kinked (vs. both antennomeres kinked); (26) mesoscutum relatively long, MI ~ 80 (vs. short, MI ~ 104–131); (27) scutoscutellar sulcus distinctly broad (vs. short, almost line-like); (28) petiole relatively long, PI ~ 80 (vs. short, PI ~ 51–67); (29) bristle-like setae apparently not developed on gastral sternites (vs. such setae present on all gastral sternites except the first); (30) abdominal sternum IX posterior margin broadly convex (vs. broadly emarginate); (31) gonostyli relatively long, length ~ 2–3 × height (vs. short, length ~ 1 × height); (32) gonostylar apices narrowly pointed (vs. broadly rounded); (33) ventral margin of penite more-or-less linear from base to apex (vs. base produced ventrally as a dorsoventrally long, anteroposteriorly narrow, serrate lobe); and (34) apicoventral penite processes short, length from proximodorsal inflection point ~ 1 × height (vs. long, length ~ 4 × height).

Notes on diagnosis:

1. A large, rhomboidal clypeal condyle is an apparent synapomorphy of the Dolichoderomorpha, i.e. Dolichoderinae + Aneuretinae. The clypeal condyle of Formicinae and other subfamilies is variable in shape, often anteroposteriorly narrow.

2. The form of the gonopod is an apparent synapomorphy of Dolichoderinae as it is not shared with Aneuretinae.

3. Most dolichoderines have a posteroventral (ventroapical) basivolsellar process, which may be short and triangular to elongate and digitate. The process is absent in Azteca Forel, 1878 and Gracilidris Wild & Cuezzo, 2006 (sister taxa), Ochetellus Shattuck, 1992 and some Dolichoderus Lund, 1831 . Formicines do not have a basivolsellar process; such a process is present convergently in the Amblyoponinae , which is a synapomorphy for that subfamily ( Yoshimura & Fisher, 2012; Boudinot, 2015).

4. In their recent phylogenetic revision of the Dolichoderinae, Ward et al. (2010) provided reduction or loss of the medial hypostomal lamina as a synapomorphy of the Bothriomyrmecini that occurs in both sexes. Subsequently, Boudinot et al. (2016) recognized loss of forewing cross-vein 2rs-m as another diagnostic condition. Here, we propose the ‘short’ condition of the clypeus as an additional synapomorphy of the tribe. The clypeus in both males and females extends posteriorly between the antennal toruli in the majority of dolichoderine genera with only a few exceptions ( Shattuck, 1992; Boudinot, 2015), such as the neotropicus and macro clades of Leptomyrmex Mayr, 1862 ( Lucky & Ward, 2010; Boudinot et al., 2016; Barden et al., 2017).

5. Males and queens of the Bornean genus Loweriella Shattuck, 1992 are unknown in contrast to the other three bothriomyrmecine genera ( Bothriomyrmex Emery, 1869a , Chronoxenus Santschi, 1919 , Ravavy ). Because Loweriella is the sister-group of Ravavy ( Ward et al., 2010) , a number of the diagnostic traits of the latter genus adduced here may be synapomorphies of the two genera.

6. Yoshimura & Fisher (2011) tentatively remarked that additional, vestigial denticles may be present in R. miafina and label a possible denticle on a dissected mandible imaged with a compound microscope. Because this apparent denticle is on the lateral mandibular margin, and as the apical tooth is a consistent feature of even ‘edentate’ mandibles ( Boudinot et al., 2021), we interpret the mandible of R. miafina as strictly unidentate.

7. The 6,3 palpomere count is an apparent synapomorphy of Ravavy within the Bothriomyrmecini . Loweriella has a plesiomorphic 6,4 count, while Bothriomyrmex and Chronoxenus share a derived, reduced count which is ≤ 4,3 ( Bolton, 2003; Fisher, 2009; Yoshimura & Fisher, 2011).

8. The fine anatomy and morphology of R. miafina is illustrated in Fisher (2009) and especiallyYoshimura & Fisher (2011). The latter work provided a revised diagnosis of this species plus a comparative analysis of genitalic form. Comparisons were made to the images in the literature, on AntWeb (2022), and to specimens examined at the California Academy of Sciences.

Description: Integument uniformly imbricate, apparently with a more-or-less even vestiture of extremely short and appressed pubescence; bristlelike setae not visible on body with exception of tarsi, gastral tergites and gonostyli, those of gastral tergites sparse. Head roughly rectangular, narrow anterad eyes and broader posteriorly; malar space relatively broad, being longer than proximal width of mandible in lateral view; posterior head margin emarginate. Compound eye bulging, length slightly less than half head-length, subreniform with subtle emargination occurring on along ventral eye margin and with> 175 ommatidia but probably not more than 200 (complete count not possible). Ocelli small; lateral ocelli relatively wideset, separated from one another by somewhat more than three lateral ocellar lengths. Frontal carinae poorly developed. Antenna 13-merous, scape about as long as compound eye and about 3 × as long as pedicel; pedicel about twice as long as wide and slightly more than half the length of antennomere III; antennomere III slightly kinked at about midlength; antennomeres III–XIII subequal in length and about 4 × as long as wide. Ocellar sensilla (setae) not visible. Anterior clypeal margin more-orless linear; clypeal setation not observable; posterior clypeal margin convex, portion of epistomal sulcus anterad and between toruli linear, weakly concave. Mandibles spiniform, tapering to their unidentate apices, thus appearing wedge-shaped in dorsal view. Labrum deeply notched apically, sides distinctly narrowing apicomediad. Palp formula 6,3; maxillary palp relatively long, exceeding hypostomal margin but not occiput; labial palp short, about one-fourth length of maxillary palp. Prementum elongate, diamond shaped. Stipes without transverse carina. Medial hypostomal lamina absent. Pronotum short, strap-like. Mesoscutum relatively long, with maximum length greater than maximum width; notauli absent; parapsides diverging anteriorly; scutoscutellar sulcus distinctly broad; lateral mesopectal sulcus sinuate. Upper metapleural region distinct, about 4 × as long as broad; lower metapleural region indistinct. Propodeum without distinct dorsal and posterior surfaces; propodeal spiracle small, circular, set slightly below metaphragmal pit. Femora puny, thin; metafemur and metatibia slightly sinuate. Tibial spur formula 1,1. Arolia small, barely visible. Petiole elliptical in lateral view, with broadly convex tergum and sternum; node not squamiform. Abdominal tergum III with broad but shallow concavity anteriorly above helcium. Abdominal segments III–VII similar in size, unmodified. Abdominal sterna VII–VIII broadly emarginate posteriorly. Abdominal sternum IX posterior margin convex, simple. Cerci not visible. Cupula not visible. Gonocoxite length uncertain; gonocoxital apex distinctly offset from gonostylar base. Gonostylus elongate, triangular; length about 2–3 × width; apex narrowly pointed. Volsellae incompletely visible; basivolsellar process present, acute; cuspis absent; lateropenite (= digitus) apex directed ventrad at nearly right angle relative to body of volsella; dorsal margin of digitus almost lobate; digital apices narrowing, almost rod-like and curved laterad. Ventral margins of penites moreor-less linear from base to apex; dorsal margins broadly convex in lateral view; apical processes directed posterad and relatively short, length from proximodorsal inflection point ~ 1 × height. Fore and hind wing venation virtually identical to R. miafina . Jugal lobe absent.

Measurements and indices: Dashes indicate metric could not be taken or calculated. Holotype: BL ~ 2.34, HL 0.54, HW 0.41, HWE 0.50, EL 0.21, MSL 0.09, FcW –, SL –, OLL –, OIL –, WL 0.91, ML 0.43, MW –, FWL 2.17, PL –, PW 0.09, PH 0.12, GL 0.86, GW 0.43, CI 92, HWI 122, MSI 6, SI –, OI 39, EPI –, OCI –, MI –, PI –. Paratype: BL ~ 2.57, HL 0.54, HW 0.41, HWE 0.48, MSL 0.09, EL 0.22, FcW 0.12, SL 0.22, OLL 0.04, OIL 0.011, WL 0.98, ML 0.46, MW 0.37, FWL 2.52, PL 0.12, PW –, PH 0.15, GL 0.93, GW 0.54, CI 90, HWI –, MSI 6, SI –, OI 40, EPI –, OCI 38, MI 80, PI 80.

Note: For comparison, see the metrics for R. miafina provided below.

Figures

Figure 4. Ravavy goldmani sp. nov., holotype male NIGP180512, photomicrographs. A, left lateral view, slightly anterioroblique orientation. B, ventral view, slightly left-lateral-oblique orientation. Scale bars: 0.5 mm.

Figure 5. Ravavy goldmani sp. nov., photomicrographs. A–B, holotype male NIGP180512, C–F, paratype male IGR. ET2015/001a. A, right lateral view, slightly posterodorsal–oblique orientation. B, oral view, slightly right–lateral–oblique orientation. C, dorsal view, slightly right lateral, anterior oblique orientation.D, ventral view, slightly right–lateral, posterior oblique orientation. E, right lateral, slightly ventral, anterior oblique view. F, caudal view of genitalia, slightly right lateral oblique. Scale bars: 0.5 mm for A, B, F; 1.0 mm for C–E.