Adetomyrma venatrix

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Adetomyrma venatrix
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Amblyoponinae
Genus: Adetomyrma
Species: A. venatrix
Binomial name
Adetomyrma venatrix
Ward, 1994

Adetomyrma venatrix casent0101400 profile 1.jpg

Adetomyrma venatrix casent0101400 dorsal 1.jpg

Specimen Label

"The twenty-one workers were collected from the lower surface of a rotten log, at the log/soil interface, in a tract of tropical dry forest in western Madagascar. The workers appeared to be foraging as a group, much in the manner of several small Cerapachys species that are characteristic of the dry forest of western Madagascar, although it is possible that they were recruiting to a prey item (not seen). Unfortunately time did not permit a detailed search for the colony. One of the workers stung my finger and this produced a noticeable stinging sensation (and later a slight swelling that persisted for several days) despite the minute size of the worker. It seems reasonable to surmise that Adetomyrma ventrix is a specialized predator or ground-dwelling arthropods." Ward (1994)

Identification

Ward (1994): (i) absence of a petiole in dorsal view (abdominal tergum 3 lacking a dorsally differentiated pretergite), (ii) gaster large and expanded posteriorly, all terga and sterna unfused and without constrictions, (iii) absence of eyes, and (iv) presence of a very large sting (larger, in relation to body size, than that of any other known ant).

Yoshimura and Fisher (2012) - The worker of Adetomyrma venatrix is easily distinguished from the other Adetomyrma species by the combination of two shorter hairs lateral to the longest hair on anterior margin of the clypeus, the lack of a small denticle on the basal portion of the mandibular subapical tooth, and the concave posterior margin of the head in full-face view. Males of A. venatrix are distinguished easily from other Adetomyrma males by their brown body color, the mesoscutum without notaulus, the relative closeness of the lateral ocellus to the eye, a clear parapsidal line, and a petiole with an anterior margin longer than its dorsal margin.

The male of Adetomyrma venatrix is relatively similar to that of Adetomyrma aureocuprea, although the former species can be separated from the latter by its brown body color and the clearly impressed parapsidal line. Morphological differences between these two species are relatively small, and A. aureocuprea shows large morphological variation. However, these two species have a sympatric distribution and the morphological differences in each sympatric site are consistent.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Habitat

Tropical forest - dry, montane and rainforest.

Abundance

Only known from a few collections.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • venatrix. Adetomyrma venatrix Ward, 1994: 161, figs. 1-7, 12, 13, 18, 24, 30, 36, 41 (w.) MADAGASCAR. Yoshimura & Fisher, 2012: 28 (m.).

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Yoshimura and Fisher (2012) - Although male specimens have not been collected with conspecific workers, males were determined to be conspecific by a comparison to the other Adetomyrma species known from the type locality of venatrix and through CO1 sequencing (Fisher unpublished data). Adetomyrma goblin, which has a known worker-male association, is the only other species known from the type locality of venatrix and their males are quite distinct.

Description

Worker

Worker measurements (n = 13). HW 0.40-0.49, HL 0.48-0.56, SL 0.29-0.34, PW 0.28-0.33, DPW 0.20-0.27, LHT 0.32-0.37. CI 0.83-0.90, SI 0.66-0.73.

Description (worker ). Small (HW < 0.50mm), pale and blind. Mandibles subfalcate, without distinct basal and masticatory margins; inner margin with 3 or (more commonly) 4 teeth, equally spaced and lying in t h e same plane as the front of the head, followed by a gap (0.05-0.06mm) and two longer (subapical and apical) teeth which, as a consequence of the curvature of the mandibles, lie in the dorsoventral plane when the mandibles are closed. Closed mandibles with apices over- lapping. Clypeus very short, its principal surface deflected ventrally, anterior margin broadly convex and furnished with a row of about 20 small, specialized, conical setae. Frontal carinae short, low, expanded laterally as small frontal lobes that over n o more than about a third of t h e antennal insertions (dorsal view). Medial portion of the antennal sclerite (torulus) upturned and fusing with the frontal carinae. Scape notably shorter than head length (SL/HL 0.59-0.61); first funicular segment c. 2.3 times longer than broad, and approximately equal to the combined length of the next three funicular segments; funicular segments 2-8 broader than long, segments 8-11 becoming gradually enlarged but not forming a distinct club. Terminal funicular segment c. 2.5 times longer than penultimate segment, and about half the scape length. Head subquadrate, longer than wide (CI 0.83-0.90), widest near the mandibular insertions; sides slightly convex, converging posteriorly and rounding into the concave posterior margin. Mesosoma dorsum somewhat flattened in profile, lateral margins rounded; in dorsa1 view pro- notum longer than broad, with convex sides, mesonotum very short and twice as wide as long. Basal (= dorsal) face of propodeum narrower than pronotum, about 1.5 times longer than wide, with subparallel sides that converge slightly towards the mesonotum; basal face of propodeum about 2.5 times the length of the declivitous face, and rounding gently into the latter. Metapleuron fully fused with propodeum, the two not distinguishable in lateral view. Metapleural gland bulla conspicuous, manifested as a large circular patch on the lower posterolateral corner of the mesosoma, its dorso-ventral height about two-thirds the length of the declivitous face of the propodeurn. Inferior propodeal (‘metapleural’) lobes essentially undeveloped. Abdominal tergum 2 c. 1.4 times broader than long, in dorsal view. Abdominal sternum 2 with a conspicuous subpetiolar process, shaped like an irregular axe blade. Abdominal sternum 3 with anteroventral surface evenly convex, lacking protuberant ridges near the helcium.

Mandibles smooth with scattered punctures. Most of body smooth and shining; head and mesosoma dorsum with numerous piligerous punctures (c. 0.010-0.015 mm diameter) separated by one to several times their diameters, densest on the head (except for a smooth puncture- free median strip). A few scattered punctures on abdominal tergum 2, remainder of metasoma with small, less conspicuous punctulae, preceded on the exposed portions of the anterior margins of each sclerite by fine transverse reticulate-striolate sculpture. Sides of propodeum and metapleuron with weak reticulations. Body with a rather dense cover of pale, erect and suberect hairs; more than 30 standing hairs visible in profile on the mesosoma dorsum; anterior margin of clypeus with a row of long (up to 0.12 mm), slender, curved setae (dorsad of the specialized tooth-like setae) that exceed the closed mandibles; erect setae also present on the scapes, funiculi, and extensor surfaces of the tibiae. Colour: light yellow-brown, with narrow darker bands at the posterior margins of abdominal segments 2 to 4 or 5.

Yoshimura and Fisher (2012) - holotype. HL 0.54, HW 0.46, SL 0.32, HD 0.32, WL 0.73, PnW 0.32, MnW 0.2, PpW 0.25, PtW 0.24, CI 84.8, SI 70.2, MnI 43.9, PpI 127, PtI 94.5.

HL 0.47–0.55, HW 0.42–0.48, SL 0.28–0.33, HD 0.29–0.34, WL 0.63–0.73, PnW 0.28–0.31, MnW 0.18–0.21, PpW 0.23–0.26, PtW 0.22–0.27, CI 83.5–92.9, SI 63.7–69.7, MnI 39.4–45.1, PpI 123.2–134.9, PtI 91–103.5 (2 paratypes and 9 individuals measured).

The following updated worker description is based largely on that in Ward (1994). Head subquadrate in full-face view, longer than wide; sides slightly convex, widening near the mandibular insertions, converging posteriorly, posterior margin concave. Clypeus short, principal surface deflected ventrally. Anterior margin of clypeus broadly convex, and furnished with a row of about 20 small, specialized, conical setae. Frontal carinae in full-face view short and low, expanded laterally as small frontal lobes covering more than about 0.33× of length of antennal insertions. Mandible subfalcate, without distinct basal and masticatory margins; inner margin with two apical teeth and four basal denticles; no denticle on base of subapical tooth (second tooth from apex); out of four denticles, apical two denticles larger (longer) than other two; apical two sometimes fused into one blunt, low denticle (observed in CASENT0129948). Palpal formula 3,3 (three maxillary and three labial). Antennal scape shorter than head length. Pedicel (second antennal segment) approximately equal to combined length of next three (third to fifth) antennal segments. Antenna gradually broadened from its third segment and not forming a distinct club. Dorsal outline of mesosoma in lateral view somewhat rounded, continuous; mesonotum not strongly raised from pronotal and propodeal dorsum. Pronotum in dorsal view longer than broad, with convex sides. Mesonotum in dorsal view short, 2× as wide as long. Metapleuron fully fused with propodeum, division of two plates not distinguishable in lateral view. Dorsal face of propodeum narrower than pronotum, about 1.5× longer than wide, with subparallel sides converging slightly toward mesonotum. Propodeum in lateral view, dorsal margin 2.5× length of declivitous margin, rounding gently into latter. Propodeal spiracle large, located distantly from propodeal dorsal margin in lateral view, partially visible in dorsal view. Subpetiolar process distinctly developed, variably shaped like an irregular axe blade. Shallow, sparse punctures covering dorsal head, mesosoma, abdomen, and ventral head; those on head dorsum denser than on other parts. Clypeus with two groups of hairs: mid clypeal hairs directed dorsally, and anterior clypeal hairs deflected anteriorly. Mid clypeal hairs consisting of one long hair and one or two shorter hairs around long one. With head in full-face view, anterior clypeal hairs consisting of one pair of long hairs and two shorter hairs laterally.

Queen

Undescribed.

Male

Yoshimura and Fisher (2012) - HL 0.56–0.63, HW 0.77–0.87, SL 0.15–0.17, EL 0.37–0.4, WL 1.32–1.58, MnW 0.89–1.02, CI 132.3–140.9, SI 19.1–20.1, EI 63.3–65.8, MnI 113.4–125 (5 individuals measured).

Eye well developed and prominent, posterior margin not exceeding posterior margin of mid ocellus in full-face view. Distance between lateral ocellus and eye slightly longer than diameter of lateral ocellus. Palpal formula 3,3 (three maxillary and three labial). Notaulus absent on mesoscutum. Parapsidal line clearly impressed with darker pigment. Anterior margin of petiole longer than dorsal margin in lateral view. Subpetiolar process poorly developed, without hairs ventrally.

Left and right parameres not overlapping or narrowly overlapping on dorsal small part of basimere. No distinct projection or lobe present on posterodorsal portion of paramere. Basal ring not reduced, covering whole anterior margin of paramere in lateral view. Basal projection on cuspis clear but not extraordinarily well developed. Aedeagus in lateral view: distal portion narrowed after ventral projection; apical margin relatively wide and dull; dorsal and ventral margins after basal projection almost symmetric; posteroventral portion without a broadly triangular projection; posteroventral margin of ventral projection convex in basal half and concave in distal half.

Hair on compound eyes short, about 0.25x diameter of mid ocellus. Mesofemur in dorsal view, anterior face covered with dense and short subdecumbent hairs, lacking hairs. Ventral margin of eye not edged with darker pigment or punctures. Body color uniform dark brown to brown.

Type Material

MADAGASCAR, Zombitse Forest, along Route Nationale 7, 15 km E Sakaraha, 760 m, 22°54’S, 44°41’E, 15 February 1993, P. S. Ward no.11932, ex rotten log, tropical dry forest. Holotype worker Museum of Comparative Zoology. Paratypes. Series of twenty workers, same data as holotype to be deposited in Australian National Insect Collection, The Natural History Museum, Los Angeles County Museum of Natural History, Museum of Comparative Zoology, Musee National d'Histoire Naturelle, Parc Botanique et Zoologique de Tsimbazaza, Phil Ward Collection, University of California, Davis.

Determination Clarifications

Adetomyrma venatrix corresponds to the following species code used in previous studies: mgm01: Yoshimura & Fisher 2012.

References