A Fine Morphological Study of the Rare Anillidris bruchi Santschi (Hymenoptera: Formicidae: Dolichoderinae) Male and Queen

Abstract

Using optical and scanning electron microscopy, we describe the following new morphologically distinctive characters of the rare Neotropical ant Anillidris bruchi Santschi, 1936, male and queen: scattered setae inter-ommatidia, semicircular hypostomal notch, antennal cleaning, metatibial spurs, and the remnant of the M2 vein in the hindwings. In males, we show for the first time the morphology of maxillary and labial palpi, the absence of metapleural glands, and, in external genitalia, for the first time in ants, a new mechano-sensory area on the volsella that we called "volsella sensorium", composed of several spine-like sensilla. Additionally, we give an updated morphological diagnosis of the alate caste, which will be useful for future studies to clarify the phylogeny of the genus Anillidris.

Keywords: SEM; ant morphology; ant spurs; external genitalia; volsella sensorium; winged ants.

Figure 1

Anillidris bruchi male. (A) habitus; (B) forewing; (C) hindwing; and (D) external genitalia in posterior view. Abbreviations: A: Anal vein; C: Costal vein; Cu: Cubital vein; cu-a: cubital-anal cross-vein; di: digitus; M: Media vein; m-cu: media-cubtus cross vein; rs-m: radial sector-media cross vein; r-rs: radius-radial sector cross vein; R: Radius vein; Rs: Radial sector; SC: Subcostal vein; te: telomere.

Figure 2

Anillidris bruchi male. (A) head in dorsal view; (B) head in lateral view; (C) head in ventral view; and (D) head in anterior view. Abbreviations: atp: anterior tentorial pit; bu: bulbus; ca: cardo; dma: dorsal clypeal mandible articulation; es: epistomal sulcus; lo: lateral ocellus; mo: median ocellus; po: postmentum; pr: prementum; rsn: regular semicircular notch; sio: setae inter-ommatidia; to: torulus.

Figure 3

Anillidris bruchi male. (A) antenna; (B) mandibles in dorsal view; (C) maxillary palpi in ventro-anterior view; and (D) labial palpi in ventral view. Abbreviations: lms: long medial clypeal setae; lp: labial palpi; mp: maxillary palpi; tls: three long clypeal setae.

Figure 4

Anillidris bruchi male. (A) mesosoma in dorsal view; (B) mesosoma in lateral view; (C) mesosoma in ventral view; and (D) petiole in lateral view. Abbreviations: ane: anepisternum; as III: abdominal sternite III; at III: abdominal tergite III; ax: axilla; lmet: lower metapleuron; kat: katepisternum; med: mesodiscrimen; medl: mesodiscrimenal line; mes: mesoscutum; mesp: mesoprefurcal pit; mess: mesoscutellum; mesx: mesocoxal foramen; met: metascutellum; metx: metacoxal foramen; pax: preaxilla; pdl: petiolar dorsal lobe; pro: pronotum; prop: propodeum; ps: propodeal spiracle; pvl: petiolar ventral lobe; te: tegula; umet: upper metapleuron.

Figure 5

Anillidris bruchi male. (A) antennal cleaning; (B) metatibial spur; (C) pretarsal claw; and (D) mesotibiae without spur. Abbreviations: ar: arolium; bc: basitarsal comb; bss: basitarsal spatulate setae; bt: probasitarsal; cc: calcar comb; cf: cuticular fringes; cfp: cuticular fringes pectinate; cw: claw; ecf: external cuticular fringes; ma: manubrium; mbt: metabasitarsal; met: mesotibiae; mebt: mesobasitarsal mt: metatibiae; mts: metatibiae spur; pt: protibiae.

Figure 6

Anillidris bruchi male. (A) external genitalia in posterior view; (B) external genitalia in lateral view; (C) external genitalia in ventral view; and (D) external genitalia in ventro-lateral view. Abbreviations: adp: apicodorsal process of the digitus; as IX: abdominal sterinite IX; pr: proctiger; ba: basimere; bs: basivolsella; bvl: basimere ventral lobe; bvp: basivolsellar process; cu: cuspis; di: digitus; pv: penis valve; py: pygostyle; te: telomere; vl: valviceps lamina.

Figure 7

Anillidris bruchi male. (A,B,D) paramere and volsella in dorsal view; and (C) paramere and volsella in ventro-mesal view. Abbreviations: adp: apicodorsal process of the digitus; as IX: abdominal sterinite IX; ba: basimere; bvl: basimere ventral lobe; bvp: basivolsellar process; cu: cuspis; vs: volsella sensorium; te: telomere.

Figure 8

Anillidris bruchi queen. (A) habitus; (B) forewing; and (C) hindwing abbreviations: 2M: Media 2 vein.

Figure 9

Anillidris bruchi queen. (A) head dorsal view; (B) head ventral view; (C) head anterior view; and (D) head lateral view. Abbreviations: dma: dorsal clypeal mandibular articulation; ma: malar area; lb: labrum; lp: labial palpi; mp: maxillar palpi; rsn: regular semicircular notch; sio: setae intra-ommatidia.

Figure 10

Anillidris bruchi queen. (A) mesosoma in dorsal view; (B) mesosoma in lateral view; (C) metapleural gland orifice; and (D) petiole in lateral view. Abbreviations: ane: anepisternum; at III: abdominal tergite III; kat: katepisternum; lmet: lower metapleuron; mtcx: metacoxe; mes: mesoscutum; mess: mesoscutellum; met: metascutellum; mgo: metapleural gland orifice; pro: pronotum; prop: propodeum; ps: propodeal spiracle; pt: petiole; pvl: petiolar ventral lobe; umet: upper metapleuron.

Figure 11

Anillidris bruchi queen. (A) antennal cleaning in anterior view; (B) antennal cleaning in posterior view; (C) metatibiae spur; and (D) last abdominal tergites and sternites in posterior view. Abbreviations: bc: basitarsal comb; bss: basitarsal spatulate setae; bt: probasitarsal; c: calcar; cc: calcar comb; cf: cuticular fringes; cfp: cuticular fringes pectinate; ecf: external cuticular fringes; gtIV: gastral tergite IV; mbt: metabasitarsal; mt: metatibiae; mts: metatibiae spur; pt: protibiae.