Corresponding author: François Brassard (
Academic editor: Brian Lee Fisher
In the past few decades, sampling of leaf litter with Winkler extractors revealed how abundant and ubiquitous ants from the genus
Brassard F, Leong C-M, Chan H-H, Guénard B (2020) A new subterranean species and an updated checklist of
With a total of 851 described extant species (
Morphologically,
Macao is a special administrative region of China located on the south side of the Pearl River Delta. Despite being an under-sampled and heavily urbanized territory with a land area of ~30 km2, it nevertheless harbors a surprisingly high ant diversity (
In this study, we used specimens collected through a holistic sampling protocol done to assess the ant fauna of Coloane Island, Macao (Brassard et al. unpublished). In particular, we focus on the
The majority of specimens examined were collected in 2019 across multiple sites in Coloane Island, Macao (
Images were taken with a Leica DFC450 camera mounted on a Leica M205 C dissecting microscope. Image montages of the specimens were taken, stacked, enhanced and measured using the Leica Application Suite v. 4.5.
Macao SAR, China: Coloane Island, Coloane North East hiking trail,
Insect Biodiversity and Biogeography Lab (
(
Morphological measurements used. For definition of each abbreviation see Table
Morphological measurements used. Morphological terminology follows
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Mandibles in full-face view triangular, eyes with a single ommatidium, anterior margin of clypeus shallowly convex, clypeal margin fringed with a continuous row of appressed spatulate hairs incurved towards midline of head, conspicuous preocular carina, dorsoventrally flattened scape, spatulate to spoon-shaped hairs on leading edge of scape, pair humeral hairs present, dorsum of head behind clypeus reticulate-punctate, side of mesosoma and disc of postpetiole smooth, postpetiole with concave anterior margin and a projecting lobe on convex posterior margin, total dental count of eight, lack of propodeal spines, and propodeal declivity angular.
(Figs
However,
Comparison of five diagnostic characters for
|
|
||||
|
|
|
|
|
|
|
1 | 1 | 1 | 1 | 1 |
|
1 | 1 | 1 | 0 | 0 |
|
0 | 0 | 0 | 0 | 0 |
|
0 | 0 | 0 | 1 | 1 |
|
1 | 0 | 0 | 1 | 0 |
|
1 | 0 | 0 | 0 | 0 |
|
1 | 0 | 0 | 0 | 0 |
|
0 | 0 | 0 | 0 | 0 |
|
0 | 0 | 1 | 1 | 0 |
|
1 | 1 | 1 | 0 | 0 |
|
1 | 0 | 0 | 0 | 0 |
|
0 | 0 | 1 | 1 | 0 |
|
0 | 0 | 1 | 0 | 0 |
|
1 | 0 | 1 | 0 | 0 |
|
1 | 0 | 0 | 0 | 0 |
|
1 | 1 | 0 | 0 | 0 |
|
1 | 1 | 1 | 0 | 0 |
|
1 | 0 | 1 | 1 | 0 |
We found that the most peculiar characteristic of
The name of this new species refers to the stratum it was collected in and to its suggested subterranean ecology.
A single worker from this species has been collected so far, found within a subterranean trap; a 15 mL falcon tube placed at a depth of 12.5 cm below the ground surface. It contained ethanol 70% and was baited with tuna mixed with honey (see Suppl. material 1: Fig. S1 for sampling design). The trap was placed in young secondary forest and was operating continuously for a period of 21 days. Little is known about the ecology of this species. However, due to the extremely reduced eyes present on the specimen and its collection through a subterranean trap, it is here suggested that the species has subterranean habits. Further reinforcing this hypothesis is the fact that extensive sampling in Hong Kong and Macao over the past 6 years focusing on ground-dwelling and leaf-litter ants using Winklers and pitfall traps never yielded this species. Nevertheless, only a single worker was found within one out of 256 subterranean traps retrieved during our sampling on Coloane Island, which indicates this species is uncommon. Our data also suggests it cohabits within the same soil layer with other ant species, including other subterranean species. Indeed, we found within the same trap one worker of
China (Guangdong, Guangxi, Hong Kong, Macao, Taiwan), Thailand.
This is a new species record for Macao. Originally described from Taiwan, this species is more widespread within continental Asia since it has also been recorded in Hong Kong, Macao, Guangdong, Guangxi (China) as well as in Thailand. In both Macao and Hong Kong (
Macao SAR, China • 28 Workers; Macao, Coloane Island, Ka Ho;
Originally from Australia,
Macao SAR, China • 3 Workers; Macao, Coloane Island, Caesars Golf Macau,
Bhutan, China (Guangdong, Hong Kong, Jiangxi, Macao, Xizang, Yunnan), India, Japan, Nepal, Thailand.
This species, first recorded in Macao in 2017 (
Macao SAR, China • 3 Workers; Macao, Coloane Island, Coloane Park;
Cambodia, China (Hong Kong, Macao, Yunnan), Myanmar, Thailand, and Vietnam.
A single worker of
Macao SAR, China • 1 Worker; Macao, Coloane Island, Coastal Trail;
This species, originally from Africa, is associated with disturbed habitats. For instance, in Hong Kong it was collected near Disneyland and the Hong Kong Airport; two heavily disturbed localities (
Macao SAR, China • 1 Worker; Macao, Coloane Island, Coloane Trail (Near C3 information point);
China (Hong Kong, Macao, Taiwan), Japan (Ryukyu Islands).
In contrast to Hong Kong, where this species has been rarely collected (
Photos of
Macao SAR, China • 22 Workers; Macao, Coloane Island, Hac Sa Reservoir family trail near 1-05-12;
This species was first recorded in Macao in 2017 (
Macao SAR, China • 3 Workers; Macao, Coloane Island, Caesars Golf Macau;
China (Fujian, Guangxi, Hong Kong, Hunan, Macao, Taiwan, Yunnan), Japan (Ryukyu Islands), Thailand.
Although widely distributed in Hong Kong across multiple habitats, including shrublands, plantations, urban forest remnants, secondary forest and Feng Shui woods (
Macao SAR, China • 1 Worker; Macao, Coloane Island, Ka Ho;
The following key relies heavily on couplets elaborated by
1 | Mandibles relatively short, not kinetic, not forming a snapping mechanism (Fig. |
|
– | Mandibles relatively elongate, edentate along inner margin and forming a snapping mechanism (i.e., trap-jaw) (Fig. |
|
2 | Antenna with 4 segments (Fig. |
|
– | Antenna with 6 segments (Fig. |
|
3 | Vertexal corners prominent (Figs |
|
– | Vertexal corners less prominent (Figs |
|
4 | With head in full-face view, the leading edge of the scape with a row of conspicuous projecting curved hairs, of which one or more, distal to the subbasal bend, distinctly curved toward the base of the scape (Fig. |
|
– | With head in full-face view the leading edge of the scape lacking projecting hairs that curve toward the base of the scape (Fig. |
|
5 | Vertexal margin strongly concave (Figs |
|
– | Vertexal margin weakly concave (Fig. |
|
6 | Pilosity on head consisting of spatulate hairs. Eye composed of a single ommatidium (Fig. |
|
– | Pilosity on head consisting of small appressed simple hairs. Eye composed of more than one ommatidium (Figs |
|
7 | Two pairs of thin remiform hairs on the vertex, with one pair on the lateral portions of vertex and the other in posteromedial position (Fig. |
|
– | Pilosity on head consisting solely of appressed spatulate hairs (Fig. |
|
8 | Petiole node in profile long and relatively flat (Fig. |
|
– | Petiole node in profile short and with a dorsal protrusion (Fig. |
|
9 | Mesopleuron and metapleuron smooth and shiny (Figs |
|
– | Mesopleuron and metapleuron sculptured (Fig. |
|
10 | Dorsum of pronotum with distinct transverse striations and without a median long stria (see Zhou 2011) ( |
|
– | Dorsum of pronotum without transverse striations and with a median long stria (Fig. |
|
11 | Dorsal (outer) surfaces of middle and hind tibiae with one or more conspicuous freely laterally projecting long hairs that are at a right-angle or near right-angle to the long axis of the segment (Fig. |
|
– | Dorsal (outer) surfaces of middle and hind tibiae and basitarsi with small simple to spatulate decumbent or appressed hairs (Fig. |
|
12 | Cuticle on side of head within the scrobe smooth and shining. Dorsal part of mesosoma smooth and shining. Eye with a single ommatidium (Fig. |
|
– | Cuticle on side of head within the scrobe reticulate-punctate. Dorsum of mesosoma sculptured. Eye with more than one ommatidium (Fig. |
|
13 | With head in full-face view the entire dorsum clothed with ground pilosity of very conspicuous pale orbicular hairs (Fig. |
|
– | With head in full-face view the dorsum either without hairs or with ground pilosity of short hairs that are simple to narrowly spatulate and usually inconspicuous (Fig. |
|
14 | Apical half of mandible with two preapical teeth, the proximal slightly longer than the distal. With alitrunk in profile posterior surface of mesonotum narrowly convex and weakly bulging, overhanging the metanotal groove. Posterodorsal corner of propodeum dentate. Head broader than long (Fig. |
|
– | Apical half of mandible with a single small inconspicuous preapical tooth, located very close to the spiniform apicodorsal tooth. With alitrunk in profile mesonotum meets propodeum at the metanotal groove, the former not narrowly convex nor bulging posteriorly, not overhanging the metanotal groove. Posterodorsal corner of propodeum rounded. Head slightly longer than broad (Fig. |
|
15 | With head in full-face view, the outer margins of the fully closed mandibles intersect the anterior clypeal margin mesad of the anterolateral clypeal angles, so that there is a section of the anterior clypeal margin that projects laterally beyond the outer line or the mandible (Fig. |
|
– | With head in full-face view, the outer margins of the fully closed mandibles intersect the anterior clypeal margin at the anterolateral clypeal angles, so that there is no section of the anterior clypeal margin that projects laterally beyond the outer line of the mandible (Fig. |
|
16 | Anterior clypeal margin shallowly transversely concave across its entire width (Fig. |
|
– | Anterior clypeal margin with a deep semicircular median impression, the anterolateral angles broadly convex on each side of the impression (Fig. |
|
17 | With head in full-face view, the fully closed mandibles triangular, with teeth present along entire length of exposed inner margin (Fig. |
|
– | With head in full-face view, the fully closed mandibles narrow or elongate-triangular, with teeth present only on distal half of exposed length of inner margin (Fig. |
|
18 | Antenna with 4 segments (Figs |
|
– | Antenna with 6 segments (Fig. |
|
19 | Fully closed mandibles in full-face view very broad proximally and strikingly tapered distally, obviously not linear or curvilinear (Figs |
|
– | Fully closed mandible in full-face view not very broad proximally nor strikingly tapered distally, linear (Fig. |
|
20 | Preapical dentition of each mandible with 2 preapical teeth (Fig. |
|
– | Preapical dentition of each mandible either absent or of a single article; when present with either a single tooth or a single denticle (9 spp.) |
|
21 | With head in full-face view mandible without preapical dentition (Figs |
|
– | With head in full-face view mandible with preapical dentition, a projecting preapical tooth (Fig. |
|
22 | With mesosoma in profile the propodeal declivity equipped with a broad and conspicuous spongiform lamella (Fig. |
|
– | With mesosoma in profile view the propodeal declivity equipped with a simple carina or at most a narrow cuticular flange (Fig. |
|
23 | Pronotal humeral hair stiff, straight, relatively short (Figs |
|
– | Pronotal humeral hair flagellate, long and slender (Fig. |
|
24 | Dorsal surface of petiole node and disc of postpetiole both smooth and shining, the two surfaces not contrasting. With petiole in dorsal view the node without a truncated anterior face. Smaller ant ( |
|
– | Dorsal surface of petiole node sharply punctate or reticulate-punctate, disc of postpetiole smooth or with very scattered faint sculptural vestiges, the two surfaces contrasting. With petiole in dorsal view the node with a short truncated anterior face; lateral margins not converging to a triangular anteromedian point. Larger ant ( |
|
25 | Preapical tooth of mandible spiniform and shallowly curved (Figs |
|
– | Preapical tooth of mandible varying from a denticle to a triangular tooth but not spiniform, the tooth shorter than the maximum width of the mandible, usually distinctly shorter (Fig. |
|
26 | Preapical tooth very small, in full-face view its length one-quarter or less of the width of the mandible at the point where the tooth arises (Figs |
|
– | Preapical tooth larger, in full-face view its length half or more of the width of the mandible at the point where the tooth arises (Fig. |
|
27 | In full-face view, external margin of mandibles straight (Figs |
|
– | In full-face view, external margin of mandibles curvilinear (Fig. |
|
28 | In full-face view, long appressed simple hairs abundant on head, antennae and mandibles (Fig. |
|
– | In full-face view, pilosity on head and antennae consisting mostly of relatively slender appressed spatulate hairs (Fig. |
|
Examples of short, not kinetic, mandibles in
Examples of antenna with 4 segments in
Examples of prominent vertexal corners in
Examples of leading edge of scape with conspicuous hairs curving towards the base of the scape in
Examples of vertexal margin strongly concave in
Examples of spatulate hairs on head and eye with a single ommatidium in
Examples of long and relatively flat petiole in
Examples of smooth and shiny mesopleuron and metapleuron in
Examples of conspicuous laterally projecting hairs on middle and hind tibiae
Examples of head with dorsum clothed with ground pilosity of conspicuous pale orbicular hairs in
Examples of anterior clypeal margin projecting laterally beyond the outer line of the mandible in
Examples of antenna with 4 segments in
Examples of mandibles of different shape: linear mandibles in
Examples of mandible without preapical dentition in
Propodeal declivity equipped with a broad and conspicuous lamella (
Examples of relatively short and straight, stiff pronotal humeral hairs in
Examples of smooth dorsal surface of petiole node and disc of postpetiole in
Example of spiniform and shallowly curved preapical tooth in
Examples of small preapical tooth in
Examples of mandible with straight external margin in
Traditionally,
Subterranean ants have adaptations, such as specific morphological characteristics, to live within the particular environmental conditions that define the underground habitat (
To collect subterranean
Another sampling method that can potentially collect subterranean
Although cities and the nature parks within them (i.e., patches of secondary forests) are rarely viewed as a refuge for biodiversity, recent work using diverse sampling approaches have shown that urban habitats can host high numbers of both native and exotic ant species (
We thank Carly McGregor, Siu Yiu, Ka-Man Vu, Si-Nga Chek, and Maria Lo for their help with field and laboratory work. We also thank the Environmental Protection Bureau, Caesars Golf Macau and the Macau Golf and Country Club for allowing us to sample on their premises. FB was supported by the Instituto para os Assuntos Municipais, Macao SAR, China, CML was supported by the Macao Foundation and the Direcção dos Serviços do Ensino Superior, BG, CML, and FB were supported by The University of Hong Kong.
Figure S1. Map of Coloane Island showcasing the 21 sites sampled
occurrence
White dots mark sites where the full protocol was done (i.e., leaf litter extraction, ground baiting, ground nests, subterranean traps and arboreal traps), whereas grey dots mark preliminary sites where only ground baiting and leaf litter extraction were done. Hand collection was also opportunistically used at each site.
Figure S2. Schematic representation of the subterranean sampling protocol used in the study
measurement
For a site, 4 different quadrats each had four traps placed 1 m apart at each of their corners (n = 16). Within a quadrat, traps were distributed at four different depths: 12.5, 25, 37.5, and 50 cm (A). Traps consisted of a 15 mL falcon tube containing 70 % ethanol at its bottom (B). To attract ants, a bait consisting of tuna mixed with honey was placed at the top of the trap. To allow ants to enter the trap, four holes were drilled on the wall of the tube.
Figure S3. Schematic representation of ground nests used in the study
measurement
Four nests blocks, each containing two entrances of the same size (1.588, 1.984, 2.381 or 3.175 mm), were placed in a bundle. A nest bundle is represented with a top view in (A) and a sideview in (B). Details of the nest and an inside chamber are shown in (C). A zoomed in inset of a nest chamber containing a queen, a worker, a larva, eggs and pupae is shown in (D). For each site, 8 nests bundles (n = 64 nests) were placed.
Figure S4. Transect design used for ground baiting
measurement
Each bait (n = 11) were placed 5 m apart along a 50 m transect. The baits, placed for 45 to 60 minutes, consisted of a 4 mm-thick slice of sausage previously dipped in honey.
Table
species data
The date refers to the first sampling event made at a site, which corresponded to the leaf litter extraction and placement of subterranean traps. Sampling protocols are defined as follows: the letter (P) signifies a partial sampling protocol (i.e., leaf litter extraction, ground baiting and hand collection), whereas the letter (F) signifies a full protocol (i.e., leaf litter extraction, ground baiting, ground nests, subterranean traps, arboreal traps and hand collection).