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Stigmatomma pagei
| Stigmatomma pagei | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Amblyoponinae |
| Tribe: | Amblyoponini |
| Genus: | Stigmatomma |
| Species: | S. pagei |
| Binomial name | |
| Stigmatomma pagei Hamer, Pierce & Guénard, 2023 | |
The type locality of S. pagei, Tai Po Kau Headland, Hong Kong SAR, China, is unique as it is a typical lowland coastal woodland of exceeding quality which is now absent in Hong Kong. The headland, now a Site of Special Conservation Interest, owes its quality to a remnant pre-war Feng Shui relict woodland, post-World War II reforestation, and 60 years with little human disturbance (Kendrick & Barretto 2006). Stigmatomma pagei was collected within what is thought to be this remnant woodland site. Whether S. pagei is relic of lowland forests in Hong Kong pre-deforestation is unknown, however sampling from higher elevation secondary and other forests habitats in Hong Kong has thus far failed to reveal additional specimens. Moreover, Tai Po Kau Headland has produced numerous new species as well as rare genera and species in Hong Kong.
Photo Gallery
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Identification
Head longer than broad (CI 87.00). Mandibles shorter than head length (MI 67.19). Clypeus with a total of six clypeal denticles; four-minute rectangular denticles; two conical bilobed denticles. Metanotal groove weakly impressed. Mesepisternum divided into katepisternum and anepisternum. Dorsolateral margin of propodeum marginated; margin begins posterior to mesonotum and extends along the whole propodeum dorsolateral margin including its declivitous face. Metapleuron and anterior area of the lateral surface of the propodeum with long longitudinal striae. In dorsal view, pronotum and propodeum bisected longitudinally by smooth cuticle with scarce punctuation. Metanotal groove weakly impressed.
Within Hong Kong, S. pagei is most morphologically similar to Stigmatomma amblyops and, assuming the presence 12 segments to the antennae, would key to this species in Xu & Chu (2012). However, numerous morphological characters differentiate both species. Firstly, the different mandible tooth composition with each tooth pair being closer together in S. pagei but more evenly spaced along the masticatory margin in S. amblyops (Fig 3A; Fig. 9C; Fig. 10C). The mandible is also distinctly convex medially (between first and final tooth pair) within S. pagei but conspicuously more linear in S. amblyops (Fig 3A; Fig. 9C; Fig. 10C). The lack of a marginated dorsolateral propodeal margin and metanotal groove in S. amblyops differs with S. pagei (Fig. 10A; Fig. 10E). Stigmatomma amblyops has a conspicuous genal tooth which is inconspicuous in S. pagei (Fig. 3A; Fig. 9C; Fig. 10D). Moreover, the median clypeal denticles are longer and distinctly extending beyond the anterior clypeal margin in S. amblyops, while the median clypeal denticles hardly projecting forward at all in S. pagei (Fig. 3A; Fig. 9C; Fig. 10C). No other species resembles S. pagei in continental Asia and eastern Asian islands. A single specimen from Borneo (CASENT0280663; bmnh-f) on AntWeb does show close morphological similarities with S. pagei, including marginated dorsolateral propodeal margin and a distinctly striate propodeal lateral surface. Both differ in terms of sculpturing and setae density, however, this is particularly obvious on the mesosomal dorsum, as well as the degree to which the posterior head margin in full face is concave. Other characters such as the anterior clypeal denticle characters and mandibular dentition are difficult to differentiate in bmnh-f due to mandible and head positioning.
Unfortunately, the holotype specimen (the only known specimen of this species) of S. pagei was damaged upon collection. The specimen has lost all funicular segments on both antennae and the majority of palp segments (Fig. 9C). The left-hand mandible has also become dissociated at the point of articulation with the head (Fig. 9C). It is likely the specimen acquired this damage during its time in the collection liquid (70% ethanol). Due the long sampling period (7 days), water evidently entered the pitfall and diluted the ethanol, contributing to specimen decomposition. Here and within the key, we assume the funicular segment count is twelve due to the close resemblance to S. amblyops and bmnh-f, as well as it’s dissimilarity to eleven antennal segmented species within the former Bannapone genus (Guénard et al., 2013; Liu et al., 2017). The palps are also highly damaged, rending segment counting impossible. Moreover, the accumulation of organic matter within and between segments as well as between striae obscured the true sculpture of the anepisternum, the posterior sculpture of the pronotal lateral area and the posterior setae on the hypopygium.
Hamer et al. (2023), Fig. 10. Stigmatomma pagei (ANTWEB1010972) holotype morphological characters. A) mesosoma dorsum; B) petiole in lateral view; C) anterior clypeal margin and mandibles; D) minute genal teeth and anterior head region; E) mesosoma in lateral view; F) terminal gastral segments in lateral view.
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Keys including this Species
Distribution
Latitudinal Distribution Pattern
Latitudinal Range: 22.4° to 22.4°.
| North Temperate |
North Subtropical |
Tropical | South Subtropical |
South Temperate |
- Source: Hamer et al., 2023
Distribution based on Regional Taxon Lists
Palaearctic Region: China (type locality).
Hamer et al. (2023), Fig. 2. Distribution map of Amblyoponinae species in Hong Kong (SAR), iNat = iNaturalist. A) Prionopelta kraepelini; B) Stigmatomma amblyops, S. crypticum, S. draconis; C) Stigmatomma luyiae, S. pagei, S. zwaluwenburgi; D) Stigmatomma nr. quadratum. Dark green zones indicate greater tree cover.
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Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Countries Occupied
| Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species. |
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Estimated Abundance
| Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species. |
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Biology
Castes
Nomenclature
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- pagei. Stigmatomma pagei Hamer, Pierce & Guénard, 2023: 14, figs. 2C, 9A-C, 10A-F (w.) CHINA (Hong Kong SAR).
Description
Worker
(n=1): HL 0.823; HW1 0.716; HW₂ 0.687; SL 0.430; ML 0.553; WL 1.061; PPW 0.374; DPL 0.353; DPW 0.444; GL 1.526; TL 4.32; CI 87.00; SI 60.06; MI 67.19; PtI 125.78.
Head. In full face view, head longer than wide (CI 87). Head margins subparallel, weakly converging posterior to maximum head width. Posterior head margin subtly concave; posterior head corners rounded. Mandibles linear, shorter than head length (MI 67.19). Mandible dentition arrangement from base to apex as follow; one large triangular unpaired tooth; four sets of paired triangular small teeth; blunt preapical tooth; blunt apical tooth. Ventral tooth within pair always larger than dorsal counterpart. Mandible inside margin convex, reaching maximum convexity between second and third pair of teeth. Scapes short (SI 60.05) and thick, as large as the apical part of mandible. On specimen examined, antennomeres damaged and absent; total antennal segment and antennomere count unknown. Antennal scrobes absent. Anterior clypeal margin broadly convex; margin lined with a total of six reduced clypeal denticles; four-minute rectangular denticles positioned medially, two conical bilobed denticles positioned on each clypeal corners. Clypeus narrowly inserted between frontal lobes. Supraclypeal area concave; expanding laterally behind frontal lobes. Frontoclypeal sulcus acute and weakly impressed. Frontal carina short. Eye absent. Palp formulae unknown (see comments).
Mesosoma. In dorsal view, pronotum broadly rounded anteriorly; median part of mesonotum constricted; widest point of pronotum and propodeum equal in width. Promesonotal suture deeply impressed both dorsally and laterally. Metanotal groove weakly impressed in dorsal view. In lateral view, angle between the dorsoposterior and the declivitous faces of propodeum obtuse; angle not marginated. In lateral view, dorsolateral margin of pronotum gradually curve. Dorsolateral margin of propodeum marginated; margin begins immediately behind mesonotum and extends down propodeal declivitous face. In dorsal view, propodeum trapezoid in shape. Mesepisternum divided into katepisternum and anepisternum. Metathoracic spiracle circular, swollen with cuticle; positioned just ventral of the anterior most point of dorsolateral propodeal margin Propodeal spiracle circular, lacking cuticular swelling. Declivitous face of propodeum flat.
Metasoma. In lateral view, petiole longer than high. Anterior face straight. Anterodorsal angle bluntly curved. Subpetiolar process present; broadly rectangular; anteroventral margin convex; ventral margin straight, posteroventral margin concave; posteroventral angle a blunt right angle. Subpetiolar fenestration absent. In dorsal view, petiolar dorsum as long as wide. Prora present. First three gastral tergites of similar length.
Sculpture. Mandibular dorsum longitudinally costate. Clypeus anteriorly smooth; posteriorly and between frontal lobes longitudinally striate. Supraclypeal area smooth. Head dorsum areolate-rugose, posterior corners smoother with scarce areolae. Pronotum, mesonotum and propodeum dorsum densely punctuate on lateral margins; pronotum and propodeum bisected longitudinally by smooth cuticle with scarce punctuation. Mesonotum medially punctuate. Pronotal lateral area punctuate; posteriorly with short, dense longitudinal striae. Katepisternum striate; anepisternum mostly smooth. Propodeal dorsum smooth; scarcely punctuate laterally. Declivitous surface of propodeum smooth. Metapleuron and anterior area of the lateral surface of the propodeum with long longitudinal striae; beginning at katepisternum, extending to propodeal postero-lateral margin, not extending onto declivitous surface; striae absent immediately below dorsolateral margin, surface smooth and shiny instead. Dorsum of petiole punctuate, punctuation dense on dorsolateral margin. Lateral surface of petiole smooth with scarce punctuation on margins. Gastral tergites one and two with confused punctuation; subsequent tergites smoother. Sternites with similar sculptural patterning. Hypopygium anteriorly imbricate; posteriorly smooth other than setal punctuation.
Setae. Dorsal surface of mandible with decumbent simple setae; inner margin with long inward directed, stout, decumbent setae; immediate ventral margin of masticatory margin with inward directing long, stout, spatulate setae. Anterior clypeal margin with a pair of long, thin setae extending in front of mandibles. Scape with appressed short setae; occasional erect setae of same length also present. Cephalic dorsal and ventral surfaces with short sub-decumbent and suberect setae; setae dense on posterior head margin. Mesosoma dorsum with short sub-decumbent and suberect setae across all segments; setae dense laterally. Petiole dorsum with short sub-decumbent and suberect setae; laterally with fewer setae. Subpetiolar process mostly glabrous; few setae on posterior margin. Dorsum of tergites with short sub-decumbent to erect setae across all segments; third to fifth tergite segments with longer setae and larger glabrous areas. Sternites with short sub-decumbent to erect setae across all segments; erect setae longer than those on tergites. Hypopygium with long, erect and sub-erect setae; presence of stout, spiniform setae posteriorly uncertain.
Colour. Head dark brown, mesosoma lighter brown. Metasoma and legs amber, contrasting with the later darker metasomal segments.
Type Material
- Holotype worker from CHINA; Hong Kong SAR, New Territories (Tai Po), Tai Po Kau Headland, 22.43471 114.19264, 74 m, pitfall trap (70% ethanol), 7-day sample time, 18-24 August 2022. Coll. M. T. Hamer & T. S. R. Silva, Determined by M. T. Hamer and Benoit Guénard. Collection code; TPK4SQ4PF3-8; specimen code; ANT-WEB1010972, ZRC.
Etymology
Stigmatomma pagei is named after the guitarist of the rock band Led Zeppelin and acclaimed guitar hero, James Patrick Page, known as Jimmy Page. While Jimmy Page wanted to become a biologist as a child but turned into music instead, there is no doubt that he has inspired generations of biologists, including the authors of this work.