Research Article |
Corresponding author: Mac P. Pierce ( mac25252007@gmail.com ) Academic editor: Marek Borowiec
© 2019 Mac P. Pierce, Chi-Man Leong, Benoit Guénard.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Pierce MP, Leong C-M, Guénard B (2019) A new species and new record of the cryptobiotic ant genus Ponera Latreille, 1804 (Hymenoptera, Formicidae) from Hong Kong. ZooKeys 867: 9-21. https://doi.org/10.3897/zookeys.867.36139
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Despite its small size, Hong Kong hosts a surprising level of ant diversity. Through faunal studies on arthropods conducted in Hong Kong over recent years, a new record and species of the genus Ponera have been discovered, which are introduced here. Ponera guangxiensis Zhou, 2001 is reported for the first time from Hong Kong, and Ponera tudigong sp. nov. is here described as a new species, easily distinguishable from other Ponera species and unique within the genus for its four mandibular teeth.
Asia, biodiversity, description, Ponerinae, taxonomy
The cryptic ant genus Ponera Latreille, 1804, contains 59 valid species at present (
At present only one species of Ponera, P. sinensis Wheeler, 1928, is known from Hong Kong and the surrounding Guangdong province. Through faunal studies conducted in Hong Kong using pitfall traps and sifted leaf-litter, two newly recorded species have been found: P. guangxiensis Zhou, 2001, and P. tudigong sp. nov., newly described in this paper. We include here accounts of the two species, the description of P. tudigong sp. nov., and an update to the key to East Asian species of Ponera presented by
Twenty-nine individuals collected from Hong Kong were examined (Figure
Morphological measurements were done using a Leica S8AP0 stereomicroscope at 80 × magnification. Measurements used are detailed below and follow those used in
Specimen images were taken using a Leica DFC450 digital camera mounted on a Leica M205C dissecting microscope, and processed using Leica Application Suite V4 software.
ATL Abdominal tergum III length. Maximum length of 3rd abdominal tergum (= 1st gastral tergum), measured from the center of the anterior margin to the center of the posterior margin, in dorsal view.
ATW Abdominal tergum III width. Maximum width of the 3rd abdominal tergum (= 1st gastral tergum), measured as a straight line from one lateral margin to the other, in dorsal view.
HL Head length. Maximum length of the head, measured as a straight line between the center of the posterior cephalic margin and the center of the anterior clypeal margin, in full-face view.
HW Head width. Maximum width of the head, measured as a straight line from one lateral margin to the other, in full-face view.
MaL Mandible length. Maximum length of the mandible, measured as a straight line from the mandibular insertion to the tip of the apical tooth, with the mandible in dorsal view.
ML Mesosomal length. Maximum length of the mesosoma, measured as a straight line from the anterior-most point of the pronotum to the posterior basal angle of the metapleuron, in profile view.
PeH Petiole height. Maximum height of the petiole, measured as a straight line from the ventral margin of the subpetiolar process to the dorsal margin of the petiole, in profile view.
PeNL Petiole node length. Length of the node of the petiole, measured as a straight line from the anterior margin of the petiole immediately above the dorsal base of the anterior petiolar tubercle to the posterior margin of the petiole, in profile view.
PeW Petiole width. Maximum width of the petiole, measured as a straight line from one lateral margin of the petiole to the other, in dorsal view.
PrW Pronotal width. Maximum width of the pronotum, measured as a straight line from one lateral margin of the pronotum to the other, in dorsal view.
SL Scape length. Maximum length of the scape, measured as a straight line from the base of the scape (excluding the basal neck and condyle).
TL Total length. Maximum horizontal length of the specimen from the anterior-most extent of the mandibles to the posterior tip of the gaster, measured in profile view.
ATI Abdominal tergum III (= 1st gastral tergum) index. ATL/ATW × 100.
CI Cephalic index. HW/HL × 100.
DPeI Dorsal petiole index. PeW/PeNL × 100.
LPeI Lateral petiole index. PeNL/PeH × 100.
PeI Petiole index. PeW/PrW ×100.
SI Scape index. SL/HW × 100.
Holotype, worker: Hong Kong Special Administrative Region, Tai Lam Country Park, 22.38079N, 114.05378E, ± 45 m, 249 m above sea level (a.s.l.), 8 November 2017 (collection code Pi-MPP-43-07, pitfall) [
Queen: same data as holotype worker (collection code Pi-MPP-43-05, pitfall) [
Hong Kong S.A.R., China.
Ponera tudigong can be distinguished from the other species in the genus by the following characters: masticatory margin of the mandible with a small denticle and four enlarged teeth (Figure
Worker (n = 1): ATL 0.43, ATW 0.46, HL 0.59, HW 0.51, MaL 0.29, ML 0.82, PeH 0.39, PeNL 0.23, PeW 0.32, PrW 0.38, SL 0.43, TL 2.3. Indices: ATI 92, CI 85, DPeI 138, LPeI 60, PeI 85, SI 84.
Queen (n = 1): ATL 0.54, ATW 0.54, HL 0.65, HW 0.56, MaL 0.41, ML 1.03, PeH 0.43, PeNL 0.25, PeW 0.35, PrW 0.47, SL 0.48, TL 2.5. Indices: ATI 101, CI 85, DPeI 140, LPeI 59, PeI 75, SI 85.
Head. In full face view, head subrectangular (Fig.
Funicular segments of antennae incrassate, increasing in length and breadth distally.
Mesosoma. In profile view, mesosomal dorsum slightly convex. Promesonotal suture and metanotal groove both present and clearly incised. Mesopleuron distinct, separated from mesonotum by a clearly incised promesonotal articulation. In dorsal view, lateral margins of pronotum and mesonotum rounded, lateral margins of propodeum slightly concave. Propodeal corner in lateral view forming a blunt angle.
Metasoma. In profile view, petiole sub-rectangular and remarkably thick compared to other species in the genus (LPeI = 59.5), with anterior and posterior margins straight and parallel; anterodorsal corner nearly right-angled, posterodorsal corner blunt; anterodorsal corner higher than posterodorsal corner. Subpetiolar process sub-rectangular in shape, with a large and circular anterior fenestra, extending across the entire ventral margin of the petiole. Posterior portion of subpetiolar process with a well-developed pair of blunted teeth. In dorsal view, petiolar node sub-oval, clearly wider than long (DPeI = 138.1), with a slightly convex anterior margin and slightly concave posterior margin. In dorsal view, abdominal tergum III (= 1st gastral tergum) wider than long (ATI = 91.8), and in profile view with a bluntly rounded anterodorsal corner.
Sculpture. Entirety of head punctate, covered by closely and evenly spaced fine puncturing. Mandibles smooth. Sculpturing of mesosoma and metasoma relatively light, ranging from puncticulate to imbricate. Mesosomal and metasomal dorsum nearly smooth.
Pilosity. Head and antennae covered by fine golden-colored pubescence. Mandibles with sparse, short, erect to sub-erect filiform hairs. Pilosity of mesosoma consisting of a fine pubescence, similar to that of the head. Fine and sparse pubescence covering each metasomal segment, becoming sparser after the fourth abdominal segment (= 2nd gastral segment). Short, golden, sub-erect to erect filiform hairs present on all metasomal segments, becoming longer and denser posteriorly from the fifth abdominal segment (= 3rd gastral segment).
Color. Coloration of entire body of the individual, excluding the legs, ranging from light to dark reddish-brown. Legs light brown.
The description of the queen of P. tudigong follows that of the worker caste, with the following differences:
Body size larger than that of the worker caste, with large, sub-circular compound eyes, 0.15 mm in diameter, present on the anterior part of the head, roughly one-third the distance to the posterior margin. Three distinct ocelli present on the posterior part of the head. Mandibles similar to worker caste (Fig.
Sub-petiolar process of the queen with a subquadrate anterior fenestra, a low and blunt downward-projecting anterior angle, and a downward-projecting square medial tooth. Abdominal tergum III (= 1st gastral tergum) as long as wide (ATI: 101).
Sculpturing, coloration, and pilosity of the queen is similar to that of the worker caste, with sculpturing slightly more pronounced.
This new species is named in honor of Tudigong (土地公), the lord of the soil and the ground, a widely venerated Chinese deity.
Ponera tudigong is known from a single location in Tai Lam country park, Hong Kong SAR. The worker and queen were collected in separate pitfall traps 5 meters apart during the same sampling period. They were initially recognized as being distinct from the other local Ponera species, P. sinensis and P. guangxiensis, based on the mandible and shape of its petiole and the absence of eyes, and was later determined to be a new species. It is the only known Ponera species with four mandibular teeth, all other species having either three (most of Ponera species), five (P. pentodontos Xu, 2001), or seven (P. taylori Bharti & Wachkoo, 2012).
Nothing is known about the biology or life history of P. tudigong. Like most species of Ponera, it is likely cryptobiotic and subterranean, as the absence of eyes might suggest. The fact that our specimens were captured in surface pitfall traps may suggest that the species does come to the surface at least occasionally, maybe at night, and possibly to forage or for reproduction purposes, given that a wingless queen was captured in addition to the worker. Of course, soil disturbance during trap emplacement may also be responsible.
Ponera tudigong is known from only a single collection event, despite a significant amount of leaf-litter and pitfall-trap sampling done throughout Hong Kong in recent years. This suggests that the species is indeed quite rare. The habitat it was collected from is a restored secondary forest, and it was collected within one meter of a well-used hiking trail.
Ponera guangxiensis Zhou, 2001A: 37, 227, figs 33, 34 (w.) CHINA. Indomalaya.
China: Guangxi province, Hong Kong S.A.R (new record); Vietnam.
Worker (n = 6): ATL 0.38–0.44, ATW 0.48–0.51, HL 0.54–0.58, HW 0.49–0.53, MaL 0.31–0.36, ML 0.74–0.81, PeH 0.38–0.41, PeNL 0.19–0.22, PeW 0.31–0.32, PrW 0.38–0.40, SL 0.38–0.42, TL 2.19–2.38. Indices: ATI 79–91, CI 85–94, DPeI 143–167, LPeI 46–54, PeI 78–84, SI 75–86.
Queen (n = 1): ATL 0.50, ATW 0.57, HL 0.59, HW 0.53, MaL 0.34, ML 0.91, PeH 0.44, PeNL 0.21, PeW 0.38, PrW 0.46, SL 0.44, TL 2.55. Indices: ATI 88, CI 89, DPeI 182, LPeI 46, PeI 82, SI 85.
Hong Kong Special Administrative Region (HKSAR), Kam Shan Country Park, New Territories, 22.37089N, 114.14839E, 18 October 2017 (KS S1-R, Winkler sifter) [IBBL, ANTWEB1016325]. HKSAR, Tai Lam Country Park, New Territories, 22.37598N, 114.04713E, 3 November 2017 (TL S2-C (B), Winkler sifter) [IBBL, ANTWEB1016405]. HKSAR, Ngong Ping, Lantau Island, 22.25403N, 113.9105E, 9 November 2017 (NP S1-C, Winkler sifter) [IBBL, ANTWEB1016486]. HKSAR, Ngong Ping, Lantau Island, 22.26537N, 113.91491E, 9 November 2017 (NP S2-C, Winkler sifter) [IBBL, ANTWEB1016506]. HKSAR, Ngong Ping, Lantau Island, 22.27144N, 113.9103E, 9 November 2017 (NP S3-C, Winkler sifter) [IBBL, ANTWEB1016519] (1 worker, 1 dealate queen). HKSAR, Pak Sha O, New Territories, 22.44743N, 114.3082E, 17 November 2017 (PSO S1-R, Winkler sifter) [IBBL, ANTWEB1016555] (1 worker, 1 dealate queen). HKSAR, Ling Wui Shan, Lantau Island, 22.24333N, 113.86932E, 4 December 2017 (LWS S1-C, Winkler sifter) [IBBL, ANTWEB1016609]. HKSAR, Ling Wui Shan, Lantau Island, 22.24333N, 113.86932E, 4 December 2017 (LWS S1-R, Winkler sifter) [IBBL]. HKSAR, Ngong Ping, Lantau Island, 22.25403N, 113.9105E, 9 November 2017 (NP S1-R, Winkler sifter) [IBBL]. HKSAR, Ngong Ping, Lantau Island, 22.25403N, 113.9105E, 9 November 2017 (NP S3-R, Winkler sifter) [IBBL] (1 worker, 1 dealate queen). HKSAR, Tai Lam Country Park, New Territories, 22.37598N, 114.04713E, 3 November 2017 (TL S2-R, Winkler sifter) [IBBL]. HKSAR, Ngong Ping, Lantau Island, 22.25396499N, 113.910478E, 428 m a.s.l., 9 November 2017 (IAS-0162, hand collected) [IBBL, ANTWEB1009802; ANTWEB1009629; ANTWEB1009803] (3 workers). HKSAR, Tai Po Kau, New Territories, 22.42833N, 114.18273E, 171 m a.s.l., 2 June 2017 (IAS-0215, hand collected) [IBBL, ANTWEB1016982; ANTWEB1009685; ANTWEB1016939] (3 workers). HKSAR, Tai Po Kau, New Territories, 22.426138N, 114.181783E, 14 July 2015 (RHL-HK-TPK-T1WM, Winkler sifter) [IBBL, RHL00642]. HKSAR, Sunset Peak, Lantau Island, 22.263923N, 113.953762E, 3 June 2015 (RHL-HK-LSP-T3WM, Winkler sifter) [IBBL, RHL00758]. HKSAR, Tai To Yan, New Territories, 22.454795N, 114.118215E, 7 August 2015 (RHL-HK-TYF-T1WJ, Winkler sifter) [IBBL, RHL01441]. HKSAR, Tai To Yan, New Territories, 22.454795N, 114.118215E, 7 August 2015 (RHL-HK-TYF-T1WM, Winkler sifter) [IBBL, RHL01467]. HKSAR, Aberdeen Reservoir, Hong Kong Island, 22.26N, 114.162E, 26 June 2015 (RHL-HK-ABR-T4WM, Winkler sifter) [IBBL, RHL02059]. HKSAR, Kadoorie Farm and Botanical Garden, New Territories, 22.4302N, 114.1192E, 14 September 2015 (RHL-HK-KFBG-T1WM, Winkler sifter) [IBBL, RHL02550]. HKSAR, Mau Ping Wood, New Territories, 22.3844N, 114.241E, 20 October 2015 (RHL-HK-MTLW-T1W J, Winkler sifter) [IBBL, RHL02599]. HKSAR, Mai Po Nature Reserve, New Territories, 22.49N, 114.04E, 10 m a.s.l., 13 September 1993 [KFBG, ANTWEB1015483; ANTWEB1015484] (2 workers). HKSAR, Sunset Peak South, Lantau Island, 22.2573N, 113.9622E, 670 m a.s.l., 8 October 1996 (Winkler sifter) [KFBG, ANTWEB1016030]. HKSAR, Mai Po Nature Reserve, New Territories, 22.486N, 114.039E, 10 m a.s.l., 13 September 1993 (Pitfall and bait). HKSAR, Shing Mun Reservoir, New Territories, 22.39718N, 114.15273E, 230 m a.s.l., 6 July 2011 (PSW16625-05, Winkler sifter). HKSAR, Tai Mo Shan, New Territories, 22.41595N, 114.12722E, 775 m a.s.l., 5 July 2011 (PSW16616-03, Winkler sifter).
Ponera guangxiensis is relatively common in collections within Hong Kong. It is most commonly collected in native secondary forests, either in leaf litter samples or by searching under stones or rotting logs. It appears to be widespread in Hong Kong, though no observations on its biology or ecology have been made.
Ponera sinensis Wheeler, 1928c: 6 (w.) CHINA (Hong Kong). Indomalaya.
Guangxi province, Yunnan province, Taiwan, Hong Kong S.A.R.
See
To the best of our knowledge, the only confirmed specimen of P. sinensis from Hong Kong is the holotype, collected by Professor F. Silvestri from an unknown location, and described by
The following is an update to the identification key to East Asian species of Ponera originally provided by
1 | In lateral view, petiolar node very thick with convex posterior margin; with upper portion of posterior margin bulging | 2 |
– | In lateral view, petiolar node not as developed and presenting straight to convex posterior margin; with upper portion of posterior margin not bulging | 3 |
2 | Petiolar node in dorsal view with slightly convex anterior margin and slightly concave posterior margin. Smaller species, HW: 0.54–0.60 mm. Body color dark | P. rishen Terayama, 2009 |
– | Petiolar node in dorsal view with strongly convex anterior margin and strongly concave posterior margin. Larger species, HW: 0.65–0.75 mm. Body color reddish brown | P. takaminei Terayama, 1996 |
3 | Eye large, each consisting of 20 or more facets. Larger species, HW: ca. 0.68 mm | P. kohmoku Terayama, 1996 |
– | Eye small, each consisting of 10 or fewer facets. Size variable | 4 |
4 | Masticatory margin of mandible with 5 subequal large teeth. Smaller species, HW: 0.53–0.55 mm | P. pentodontos Xu, 2001 |
– | Masticatory margin of mandible with 3 or 4 enlarged teeth. Size variable | 4’ |
4’ | Masticatory margin of mandible with 4 enlarged teeth followed by a small denticle | P. tudigong sp. nov. |
– | Masticatory margin of mandible with 3 enlarged teeth followed by a series of small to indistinct denticles; the number of denticles variable | 5 |
We thank Dr. Zheng-Hui Xu, Dr. Shan-Yi Zhou, and Dr. Mamoru Terayama for providing images and specimens of Asian Ponera species for comparison. We thank Kit Lam Tang Wilfred for assistance in imaging and preparing the specimens. We thank members of the IBBL for general support and discussion. We also thank Jack Longino, Gabriela Camacho, and Peter Hawkes for helpful comments that improved the manuscript. This study was funded by the Environment and Conservation Fund of the Hong Kong SAR, ECF Project 32/2015.