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Stigmatomma draconis
| Stigmatomma draconis | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Amblyoponinae |
| Tribe: | Amblyoponini |
| Genus: | Stigmatomma |
| Species: | S. draconis |
| Binomial name | |
| Stigmatomma draconis Hamer, Pierce & Guénard, 2023 | |
Stigmatomma draconis was collected via litter and soil sifting within the lowland-montane floristic transition zone (500-550 m) in a secondary forest on the slopes of Tai Mo Shan at 525 m a.s.l. Though not pristine, owing to clear historic anthropogenic disturbance (e.g. tea terraces), the habitat has had a long history of reforestation and lack of human disturbance post-WWII. Here the leaf litter layer is deep, and samples rich in ant diversity (unpublished data). Further sampling at the site, and surrounding site did not reveal additional specimens.
Photo Gallery
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Identification
Head quadrate, slightly wider than long (CI 106.71). Mandibles distinctly shorter than head (MI 52.75). Mandibular dentition asymmetrical; in full face view, left hand mandible with eight teeth, right hand mandible with nine teeth visible; pairs of teeth present; third tooth from apex short and recurved; preapical tooth blunt. Anterior clypeus margin with ten denticles; six median rectangular denticles; four-minute semi-rectangular denticles laterally. Supraclypeal area with confused sculpture. Total of eleven antennal segments. Lateral face of propodeum and declivitous face marginated. Mesepisternum divided into katepisternum and anepisternum. Hypopygium posteriorly with short stout setae.
Stigmatomma draconis is superficially similar to Stigmatomma pertinax, a species described from Northern India. The holotype specimen of S. draconis will key to S. pertinax within the key in Xu et al. (2012). Comparing both species, however, reveals clear morphological differences that we think provide adequate evidence to consider it as a separate species. Firstly, the third tooth from the apex is entirely differently shape in S. draconis: it is less apically protruding, recurved towards mandible base with a small acute apex (Fig. 7A-B). The preapical tooth is also differently shaped, being shorter, apically blunt and firmly attached to the mandible on its ventral margin (Fig 5C; Fig. 6D; Fig. 7A-B). Moreover, the S. draconis holotype has paired teeth, which the holotype of S. pertinax lacks (Fig 5C; Fig. 6D; Fig. 7B). It should be noted however that in S. draconis the left hand smaller, dorsal tooth in the first tooth pair, is absent, reducing the number of paired teeth on the left-hand mandible to eight. Baroni Urbani (1978) gave the number of mandibular teeth to be seven in the S. pertinax holotype. Interestingly, variation is seen in the mandibular teeth characters of other specimens determined to be S. pertinax (CASENT0172385 from India (CASENT0172395, CASENT0172385) and Nepal (CASENT0280668). Most variable is the third tooth from the apex, all which recurve towards the mandible base (unlike the holotype) but differ in length and overall size.
Additional differing morphological characters between S. pertinax and S. draconis include a less concave posterior head margin, more sculptured supraclypeal area and a less convex anterior clypeal margin. The anterior clypeal margin is also distinctly less convex than S. pertinax, and although, a less reliable character, the number of clypeal denticles is larger in S. draconis with a total of ten compared to eight in S. pertinax. In full face view it seems like a genal tooth is present in S. draconis. However, when seen in posterolateral and ventral view the extension originates from the posterolateral head capsule and is not an anterolateral extension of the gena (Brown 1960). In direct ventral view, minute teeth can also be seen (Fig. 6D). Baroni Urbani (1978) stated that the genal angles in the S. pertinax holotype were ‘well rounded’ and did not mention posterolateral cuticular extensions or minute ventral teeth. Unfortunately, these characters are not visible in the holotype image (CASENT0906831) but in full face view, such an extension seems absent unlike in S. draconis. Finally, both species are originating from two distant regions; the mid-eastern Himalayan foothills for S. pertinax and the lowland coastal region of Hong Kong for S. draconis.
Hamer et al. (2023), Fig. 6. Stigmatomma draconis (ANTWEB1010999) holotype morphological characters. A) mesosoma dorsum; B) petiole in lateral view; C) terminal gastral segments in lateral view; D) head in ventral view, showing minute posterolateral teeth, anterior clypeal denticles and mandibular teeth; E) mesosoma in lateral view; F) petiole dorsum.
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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.
- draconis. Stigmatomma draconis Hamer, Pierce & Guénard, 2023: 10, figs. 2B, 5A-C, 6A-F, 7B (w.) CHINA (Hong Kong SAR).
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Description
Worker
(n=1); HL 0.477; HW1 0.509; HW₂ 0.490; SL 0.269; ML 0.385; WL 0.633; PPW 0.249; DPL 0.158; DPW 0.266; GL 0.735; TL 2.39; CI 106.71; MI 52.75; SI 80.71; PtI 168.35
Head. In full face view, head quadrate, slightly wider than long (CI 106.71). Lower and maximum head width approximately equal (HW1 0.509; HW₂ 0.490). Posterior head margin subtlety concave. In full face view, anterior half of lateral margins of head subparallel slightly increasing until mid-point, with posterior half narrowing progressively until posterior head corners. Posterior head corners margins broadly rounded. Mandibles long and linear; distinctly shorter than head (MI 52.75). Mandible tooth composition from base to apex as follows; two broadly based triangular teeth; two pairs of narrowly based teeth (see comments); short and recurved; preapical blunt tooth; acute apical tooth. Ventral most tooth in pair always larger than dorsal tooth. Genal tooth absent (see comments). Anterior clypeus margin evenly convex, with ten denticles; six median rectangular denticles and four-minute semi-rectangular denticles laterally. Clypeus narrowly inserted between frontal lobes. Frontal clypeal sulcus broadly rounded. Supraclypeal area concave. Frontal lobes concealing antennal foramen. Frontal carina short. Antennal scrobes absent. Scapes short, half the length of head (SI 80.71); eleven antennal segments; ten antennomeres; pedicle constricted distally. Eye absent. Palp formulae unknown, obscured by labrum. Genal tooth absent.
Mesosoma. In dorsal view, anterior part of pronotum acutely rounded. Mesosoma constricted medially behind pronotum. Pronotum just wider than propodeum. Promesonotal suture clearly distinct, metanotal groove absent. Angle between propodeal dorsum and declivitous surface blunt. Dorsolateral margins of pronotum and propodeal dorsum gradually curved. Lateral face of propodeum and declivitous face marginated. Mesepisternum divided into katepisternum and anepisternum. Metathoracic spiracle indistinct. Propodeal spiracle circular; cuticle swollen dorso-posteriorly. Declivitous face of propodeum subtlety concave.
Metasoma. In lateral view, petiole higher than long. Anterior face of petiole straight; anterodorsal angle blunt, only just obtuse. Petiole wider than long in dorsal view. Subpetiolar process present and thick; in lateral view, ventral margin convex, posterior margin straight. Subpetiolar process fenestration absent. Prora present. Gastral tergite one, wider than petiole in dorsal view; gastral segment two longer than all other tergites.
Sculpture. Mandibular dorsum costate, apical most surface smooth. Head dorsum costate-foveolate; foveolate only in posterior corners. Clypeus smooth medially, punctuate laterally. Supraclypeal area with confused sculpture. Dorsum of pronotum, mesonotum, propodeum costate-foveolate. Lateral surface of pronotum punctuate, weakly strigulate, with distinct smooth patches between sculpture. Katepisternum strigulate. Anepisternum punctuate. Lateral propodeal surface anteriorly strigulatepunctulate, posteriorly strigulate. Declivitous face of propodeum smooth. Subpetiolar process densely punctuate. Petiole dorsum punctuate, medially smooth with scarce punctuation. Lateral petiole tergite strigulate, scarcely punctuate. All gastral tergites punctuate; tergite one smooth medially; tergite two imbricate anteriorly. All gastral sternites punctuate.
Setae. Dorsum of mandible with fully erect and suberect setae on outer margin; inner masticatory margin with thick, inwardly projecting setae. Clypeus with two long setae projecting outwards over the mandibles set among numerous short setae. Scapes and funicular segments with sub-decumbent setae. Head, mesosoma, petiole and gastral tergites covered with sub-erect setae. Erect setae scattered across the mesosoma dorsum, petiole and gastral tergite among sub-erect setae; erect hairs more abundant on final three gastral tergites. Erect setae projecting posterolaterally on gastral tergites in dorsal view. Setae on gastral sternites less dense with a greater abundance of erect setae. Hypopygium with numerous erect setae anteriorly; posteriorly with short stout setae (too small to count).
Colour. Core body segments light orange, legs and antennae lighter yellow
Type Material
- Holotype worker from CHINA; Hong Kong SAR, New Territories, Tai Mo Shan Country Park, 22.42392803 114.129858, 525 m, 04 September 2022, Winkler of random leaf litter and soil, extracted over 6 days. Coll. M. T. Hamer & J. H. Park, det. M. T. Hamer & Benoit Guénard, Collection code; TMS1GC1-1, specimen code ANT-WEB1010999, ZRC.
Etymology
Stigmatomma draconis (draconis meaning of the dragon) is named for the superheated steam vents on Kwun Yam Shan mountain, near the collection locality, which is part of an inactive Jurassic volcano system. Local people call these superheated steam vents and resulting smoke like steam ‘dragon breath’. The phenomenon is particularly apparent when the surface temperatures are cold.