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Overview

Brief Summary

Biology

Colonies of Dracula ants may contain as many as 10,000 workers, winged males and several wingless queens (4) (5). The workers go out each day to capture prey, which they stun using venom, to bring back to the colony for the larvae to feed upon. It is the unique and bizarre feeding habits of the queen and workers, however, which has fascinated researchers. Hungry Dracula ants scratch and chew holes into their larvae and suck out the hemolymph, the ant equivalent of blood (4). This practice has been described as a form of 'non-destructive cannibalism', since the larvae are not killed by it. Nevertheless, when hungry workers enter the chamber, the larvae have been observed attempting to flee and escape their fate (6). Winged males are thought to disperse by flying to other colonies before mating (4). However, the colonies reproduce by budding (fission), with colony fission in ants being synonymous with short-range dispersal on foot because the queens are wingless. This has dramatic consequences on both gene flow and colonisation patterns and thus Dracula ants may be more susceptible to habitat disturbance (8).
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Description

The recently discovered Dracula ant is a highly unusual species, so named because of its grisly feeding habits of drinking the blood of its young (2) (3). First described in 1994, these ants did not attract much scientific attention until the discovery of an entire colony in 2001 (4). The Dracula ant has since attracted widespread interest not only because of this curious behaviour, but also because of its seemingly ancestral morphology (5) (6). Unlike most ants, these orange coloured ants have abdomens that closely resemble those of wasps, from which ants are believed to have descended some 70 to 80 million years ago (2) (3). Thus, they have been described as a possible 'missing link' in ant evolution (5). Winged males are a darker orange than the workers, the queen is yellow and the larvae are white (3) (4).
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Comprehensive Description

Adetomyrma venatrix HNS sp. n. (Figs 1 - 7,12,13, 18, 24, 30,

36, 41)

Holotype worker. 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 ( MCZC ) .

Paratypes . Series of twenty workers, same data as holotype (to be deposited in ANIC , BMNH , LACM , MCZC , MNHN , PBZT , PSWC , UCDC ) .

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 <0.50 mm), pale and blind. Mandibles subfalcate, without distinct basal and masticatory margins (Fig. 12); inner margin with 3 or (more commonly) 4 teeth, equally spaced and lying in the same plane as the front of the head, followed by a gap (0.05 - 0.06 mm) 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 overlapping. Clypeus very short, its principal surface deflected vent rally, anterior margin broadly convex and furnished with a row of about 20 small, specialized, conical setae (Figs 7, 12). Frontal carinae short, low, expanded laterally as small frontal lobes that over no more than about a third of the 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 (Fig. 6), 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 dorsal view pronotum longer than broad, with convex sides, mesonotum very short and twice as wide as long (Fig. 4). 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 (Figs 1, 24). 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 dorsoventral height about two-thirds the length of the declivitous face of the propodeum. 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 (Fig. 2). 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 con- sulcuous punctalae preceded on the exposed portions or the interior 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 extension surfaces of the tibiae. Colour: light yellow-brown, with narrow darker bands at the posterior margins of abdominal segments 2 to 4 or 5.

Comments. Features of Adetomyrma venatrix HNS that are likely to be species-specific include the small size, man-dibular dentition, body sculpture, dense standing pilosity, size and density of clypeal setae, and shape of the antero-ventral petiolar tooth.

Larva. A single ant larva, recovered from the vial con-taining the workers, may be that of A. venatrix HNS . It is 2.46 mm long and essentially " leptanilloid " (Wheeler & Wheeler, 1976) in shape, i. e. long, slender, and club-shaped, widest neat the posterior end (at abdominal segments 8 and 9). The thorax is slender and curved ventrally. The body hairs are numerous, short and inconspicuous. No thoracic protuberances or specialized dorsal tubercles were detected.

Biology. 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 HNS 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 thai Adetomyrma venatrix HNS is a specialized

predator or ground-dwelling arthropods. The apparent group foraging behaviour is suggestive of the habits of leptanilline ants (Masuko. 1990) and true army arm (Got-wald. 1982) and leads to the prediction that the queen of Adetomyrma HNS will prove to be a morphologically specialized wingless female.

The collection took place after a period of exceptionally heavy rains on this part of the island that effectively broke a 2 - year drought. It seems likely that this ant is usually subterranean and elusive, and that its discovery was aided by the wet soil conditions. A Winkler litter sample taken at the same site faded to produce additional material of Adetomyrma HNS .

The Zombitse Forest where Adetomyrma HNS was found (see illustration in Tattersall. 1982: 31). although falling within the bounds of what is considered tropical dry forest, is nevertheless more [[ ... ]] than most of the dry forests of western Madagascar. Moreover, the forest is under severe threat from human activities. Large swaths of the forest along Route Nationale 7 east of Sakaraha have been destroyed by slash-and-burn agriculture. After a few cycles of corn and other crops the land becomes a degraded savannah woodland. It seems certain that the collection site forAdetomyrma HNS which is located no more than 100 m from the main road will suffer the same fate unless urgent protective measures are taken.

Relationship to other formicids

Adetomyrma HNS presents something of a puzzle. At first glance it would appear to be unplaceable in any of the existing ant subfamilies since it possesses none of the derived traits that individually characterize them (Baroni Urbani et al.

incompleta HNS .

1992; Bolton, 1994), In Bolton's (1994) subfamily key, for example, it stalks at couplet 11 - a terminal couplet for Apomyrminae HNS and Ponerinae HNS (part) - because it dis-plays a mixture of features from both lugs of the couplet. The lack of tergosternal fusion of abdominal segment 4 would seem to preclude placement of Adetomyrma HNS in the Ponerinae HNS . At the same time Adetomyrma HNS exhibits almost none of the distinctive characteristics of the ' doryline section' of subfamilies (Bolton, 1990 b) such as a horizontal torulus. protruding helcial sternite specialized pygidium. reduction / loss of furcula, metatibial gland, or cuticular flap over the metapleural gland. The exposed spiracle on abdominal segment 5 is reminiscent of the greater exposure that occurs, presumably convergently, in the doryline section. Finally, the unfused condition of abdominal segment 3 inAdetomyrma HNS indicates that it does not even belong to the more inclusive ' poneroid group' (Bolton, 1990 b), i. e. that group of subfamilies, comprising Ponerinae HNS , Leptanillinae HNS , Apomyrminae HNS and the ' doryline section', whose workers show tergosternal fusion of abdominal segment 3 and all castes of which exhibit fusion of the presclerites of the same segment (Bolton, 1990 b; Ward, 1990; Baroni Urbani et al., 1992). Since Adetomyrma HNS has an apparently fused helcium (presclerites 3) this could imply that it is in a basal position, perhaps as a sister of the entire poneroid group.

A survey of additional character systems, beyond those used for subfamily characterization, became necessary for clarifying the phylogenetic affinities of Adetomyrma HNS . Focussing in particular on the morphology of the clypeal setae, metapleural gland, metacoxal cavities and petiolar sclerites, this survey revealed striking similarities (documented below) between Adetomyrma HNS and members of the ponerine tribe Amblyoponini HNS , but not between Adetomyrma HNS and any other ants. The results support placement of Adetomyrma HNS in this tribe, and hence in the subfamily Ponerinae HNS , despite the absence of tergosternal fusion.

  • Ward, P. S. (1994): Adetomyrma, an enigmatic new ant genus from Madagascar (Hymenoptera: Formicidae), and its implications for ant phylogeny. Systematic Entomology 19, 159-175: 161-167, URL:http://atbi.biosci.ohio-state.edu/HymOnline/reference-full.html?id=2959
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Taxonomic History

Adetomyrma venatrix Ward, 1994 PDF: 161, figs. 1-7, 12, 13, 18, 24, 30, 36, 41 (w.) MADAGASCAR. AntCat AntWiki

Taxonomic history

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Distribution

Range

Endemic to Madagascar (1).
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Physical Description

Diagnostic Description

Taxonomic Treatment

Ward, P. S., 1994:
 Holotype worker. 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 ( MCZC ) .
 Paratypes . Series of twenty workers, same data as holotype (to be deposited in ANIC , BMNH , LACM , MCZC , MNHN , PBZT , PSWC , UCDC ) .
 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 <0.50 mm), pale and blind. Mandibles subfalcate, without distinct basal and masticatory margins (Fig. 12); inner margin with 3 or (more commonly) 4 teeth, equally spaced and lying in the same plane as the front of the head, followed by a gap (0.05 - 0.06 mm) 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 overlapping. Clypeus very short, its principal surface deflected vent rally, anterior margin broadly convex and furnished with a row of about 20 small, specialized, conical setae (Figs 7, 12). Frontal carinae short, low, expanded laterally as small frontal lobes that over no more than about a third of the 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 (Fig. 6), 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 dorsal view pronotum longer than broad, with convex sides, mesonotum very short and twice as wide as long (Fig. 4). 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 (Figs 1, 24). 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 dorsoventral height about two-thirds the length of the declivitous face of the propodeum. 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 (Fig. 2). 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 con- sulcuous punctalae preceded on the exposed portions or the interior 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 extension surfaces of the tibiae. Colour: light yellow-brown, with narrow darker bands at the posterior margins of abdominal segments 2 to 4 or 5.
  Comments. Features of Adetomyrma venatrix that are likely to be species-specific include the small size, man-dibular dentition, body sculpture, dense standing pilosity, size and density of clypeal setae, and shape of the antero-ventral petiolar tooth.
  Larva. A single ant larva, recovered from the vial con-taining the workers, may be that of A. venatrix . It is 2.46 mm long and essentially " leptanilloid " (Wheeler & Wheeler, 1976) in shape, i. e. long, slender, and club-shaped, widest neat the posterior end (at abdominal segments 8 and 9). The thorax is slender and curved ventrally. The body hairs are numerous, short and inconspicuous. No thoracic protuberances or specialized dorsal tubercles were detected.
  Biology. 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 thai Adetomyrma venatrix is a specialized
  predator or ground-dwelling arthropods. The apparent group foraging behaviour is suggestive of the habits of leptanilline ants (Masuko. 1990) and true army arm (Got-wald. 1982) and leads to the prediction that the queen of Adetomyrma will prove to be a morphologically specialized wingless female.
  The collection took place after a period of exceptionally heavy rains on this part of the island that effectively broke a 2 - year drought. It seems likely that this ant is usually subterranean and elusive, and that its discovery was aided by the wet soil conditions. A Winkler litter sample taken at the same site faded to produce additional material of Adetomyrma .
  The Zombitse Forest where Adetomyrma was found (see illustration in Tattersall. 1982: 31). although falling within the bounds of what is considered tropical dry forest, is nevertheless more [[ ... ]] than most of the dry forests of western Madagascar. Moreover, the forest is under severe threat from human activities. Large swaths of the forest along Route Nationale 7 east of Sakaraha have been destroyed by slash-and-burn agriculture. After a few cycles of corn and other crops the land becomes a degraded savannah woodland. It seems certain that the collection site for Adetomyrma which is located no more than 100 m from the main road will suffer the same fate unless urgent protective measures are taken.
 Relationship to other formicids
 Adetomyrma presents something of a puzzle. At first glance it would appear to be unplaceable in any of the existing ant subfamilies since it possesses none of the derived traits that individually characterize them (Baroni Urbani et al.
 incompleta .
  1992; Bolton, 1994), In Bolton's (1994) subfamily key, for example, it stalks at couplet 11 - a terminal couplet for Apomyrminae and Ponerinae (part) - because it dis-plays a mixture of features from both lugs of the couplet. The lack of tergosternal fusion of abdominal segment 4 would seem to preclude placement of Adetomyrma in the Ponerinae . At the same time Adetomyrma exhibits almost none of the distinctive characteristics of the ' doryline section' of subfamilies (Bolton, 1990 b) such as a horizontal torulus. protruding helcial sternite specialized pygidium. reduction / loss of furcula, metatibial gland, or cuticular flap over the metapleural gland. The exposed spiracle on abdominal segment 5 is reminiscent of the greater exposure that occurs, presumably convergently, in the doryline section. Finally, the unfused condition of abdominal segment 3 in Adetomyrma indicates that it does not even belong to the more inclusive ' poneroid group' (Bolton, 1990 b), i. e. that group of subfamilies, comprising Ponerinae , Leptanillinae , Apomyrminae and the ' doryline section', whose workers show tergosternal fusion of abdominal segment 3 and all castes of which exhibit fusion of the presclerites of the same segment (Bolton, 1990 b; Ward, 1990; Baroni Urbani et al., 1992). Since Adetomyrma has an apparently fused helcium (presclerites 3) this could imply that it is in a basal position, perhaps as a sister of the entire poneroid group.
  A survey of additional character systems, beyond those used for subfamily characterization, became necessary for clarifying the phylogenetic affinities of Adetomyrma . Focussing in particular on the morphology of the clypeal setae, metapleural gland, metacoxal cavities and petiolar sclerites, this survey revealed striking similarities (documented below) between Adetomyrma and members of the ponerine tribe Amblyoponini , but not between Adetomyrma and any other ants. The results support placement of Adetomyrma in this tribe, and hence in the subfamily Ponerinae , despite the absence of tergosternal fusion.
 
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Holotype worker. 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 ( MCZC ) .

 

Paratypes . Series of twenty workers, same data as holotype (to be deposited in ANIC , BMNH , LACM , MCZC , MNHN , PBZT , PSWC , UCDC ) .

 

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 <0.50 mm), pale and blind. Mandibles subfalcate, without distinct basal and masticatory margins (Fig. 12); inner margin with 3 or (more commonly) 4 teeth, equally spaced and lying in the same plane as the front of the head, followed by a gap (0.05 - 0.06 mm) 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 overlapping. Clypeus very short, its principal surface deflected vent rally, anterior margin broadly convex and furnished with a row of about 20 small, specialized, conical setae (Figs 7, 12). Frontal carinae short, low, expanded laterally as small frontal lobes that over no more than about a third of the 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 (Fig. 6), 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 dorsal view pronotum longer than broad, with convex sides, mesonotum very short and twice as wide as long (Fig. 4). 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 (Figs 1, 24). 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 dorsoventral height about two-thirds the length of the declivitous face of the propodeum. 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 (Fig. 2). 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 con- sulcuous punctalae preceded on the exposed portions or the interior 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 extension surfaces of the tibiae. Colour: light yellow-brown, with narrow darker bands at the posterior margins of abdominal segments 2 to 4 or 5.

 

Comments. Features of Adetomyrma venatrix that are likely to be species-specific include the small size, man-dibular dentition, body sculpture, dense standing pilosity, size and density of clypeal setae, and shape of the antero-ventral petiolar tooth.

 

Larva. A single ant larva, recovered from the vial con-taining the workers, may be that of A. venatrix . It is 2.46 mm long and essentially " leptanilloid " (Wheeler & Wheeler, 1976) in shape, i. e. long, slender, and club-shaped, widest neat the posterior end (at abdominal segments 8 and 9). The thorax is slender and curved ventrally. The body hairs are numerous, short and inconspicuous. No thoracic protuberances or specialized dorsal tubercles were detected.

 

Biology. 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 thai Adetomyrma venatrix is a specialized

 

predator or ground-dwelling arthropods. The apparent group foraging behaviour is suggestive of the habits of leptanilline ants (Masuko. 1990) and true army arm (Got-wald. 1982) and leads to the prediction that the queen of Adetomyrma will prove to be a morphologically specialized wingless female.

 

The collection took place after a period of exceptionally heavy rains on this part of the island that effectively broke a 2 - year drought. It seems likely that this ant is usually subterranean and elusive, and that its discovery was aided by the wet soil conditions. A Winkler litter sample taken at the same site faded to produce additional material of Adetomyrma .

 

The Zombitse Forest where Adetomyrma was found (see illustration in Tattersall. 1982: 31). although falling within the bounds of what is considered tropical dry forest, is nevertheless more [[ ... ]] than most of the dry forests of western Madagascar. Moreover, the forest is under severe threat from human activities. Large swaths of the forest along Route Nationale 7 east of Sakaraha have been destroyed by slash-and-burn agriculture. After a few cycles of corn and other crops the land becomes a degraded savannah woodland. It seems certain that the collection site for Adetomyrma which is located no more than 100 m from the main road will suffer the same fate unless urgent protective measures are taken.

 

Relationship to other formicids

 

Adetomyrma presents something of a puzzle. At first glance it would appear to be unplaceable in any of the existing ant subfamilies since it possesses none of the derived traits that individually characterize them (Baroni Urbani et al.

 

incompleta .

 

1992; Bolton, 1994), In Bolton's (1994) subfamily key, for example, it stalks at couplet 11 - a terminal couplet for Apomyrminae and Ponerinae (part) - because it dis-plays a mixture of features from both lugs of the couplet. The lack of tergosternal fusion of abdominal segment 4 would seem to preclude placement of Adetomyrma in the Ponerinae . At the same time Adetomyrma exhibits almost none of the distinctive characteristics of the ' doryline section' of subfamilies (Bolton, 1990 b) such as a horizontal torulus. protruding helcial sternite specialized pygidium. reduction / loss of furcula, metatibial gland, or cuticular flap over the metapleural gland. The exposed spiracle on abdominal segment 5 is reminiscent of the greater exposure that occurs, presumably convergently, in the doryline section. Finally, the unfused condition of abdominal segment 3 in Adetomyrma indicates that it does not even belong to the more inclusive ' poneroid group' (Bolton, 1990 b), i. e. that group of subfamilies, comprising Ponerinae , Leptanillinae , Apomyrminae and the ' doryline section', whose workers show tergosternal fusion of abdominal segment 3 and all castes of which exhibit fusion of the presclerites of the same segment (Bolton, 1990 b; Ward, 1990; Baroni Urbani et al., 1992). Since Adetomyrma has an apparently fused helcium (presclerites 3) this could imply that it is in a basal position, perhaps as a sister of the entire poneroid group.

 

A survey of additional character systems, beyond those used for subfamily characterization, became necessary for clarifying the phylogenetic affinities of Adetomyrma . Focussing in particular on the morphology of the clypeal setae, metapleural gland, metacoxal cavities and petiolar sclerites, this survey revealed striking similarities (documented below) between Adetomyrma and members of the ponerine tribe Amblyoponini , but not between Adetomyrma and any other ants. The results support placement of Adetomyrma in this tribe, and hence in the subfamily Ponerinae , despite the absence of tergosternal fusion.

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Ward, P. S.

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Ecology

Habitat

Habitat and Ecology

Systems
  • Terrestrial
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Colonies have been found in rotting logs (4) and leaf litter (3) in tropical dry forest (7) in one of Madagascar's last remaining high plateau forests just outside the country's capital (5).
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Adetomyrma venatrix

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 5
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
B1+2c

Version
2.3

Year Assessed
1996
  • Needs updating

Assessor/s
Social Insects Specialist Group

Reviewer/s

Contributor/s
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Status

Classified as Critically Endangered (CR) on the IUCN Red List 2006 (1).
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Threats

The precise threats facing this recently discovered species are unknown, but the dramatic growth of Madagascar's human population and associated residential, agricultural and industrial development are known to be having a severe detrimental effect on the country's forest habitat (6). Thus, habitat loss is likely to play an important role in the decline of these ants, as it has with many of the island's other endemic fauna.
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Management

Conservation

Entomologist Dr. Fisher of the California Academy of Sciences, who first discovered an entire colony of Dracula ants in 2001, has moved a few colonies into a laboratory environment (6). This not only allows the species to be studied in greater depth, but also serves as a buffer against total extinction. Indeed, it is feared that these relics of an earlier stage of evolution may disappear from the wild completely in less than a decade (6).
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Wikipedia

Adetomyrma venatrix

Adetomyrma venatrix is an endangered species of ants endemic to Madagascar. Workers of this species are blind. The species was described as the type species of Adetomyrma in 1994, with the genus being an atypical member of its tribe.

Description[edit]

Head of a blind worker

Adetomyrma venatrix was described on the basis of specimens belonging to the worker caste collected from Zombitse Forest, in western Madagascar. The key characteristics of the species was the absence of a clear petiole when viewed from above due to the third abdominal tergite (the sclerite on the dorsal side) lacking a differentiated pretergite. The gaster is large and without constrictions. The ant is blind and has a long sting. It was placed with reservations in the tribe Amblyoponini as it lacks the typical characters of the group.[3] Later studies considered them as being close to the ancestral members of the Amblyoponinae and they share certain morphological features with Amblyopone pluto such as the presence of laterosclerite.[4][5]

References[edit]

  1. ^ Social Insects Specialist Group (1996). Adetomyrma venatrix. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 10 May 2009.
  2. ^ Ward, P. S. (1994). "Adetomyrma, an enigmatic new ant genus from Madagascar (Hymenoptera: Formicidae), and its implications for ant phylogeny". Systematic Entomology 19 (2): 159–175. doi:10.1111/j.1365-3113.1994.tb00585.x. 
  3. ^ Fisher, BL (1997). "Biogeography and ecology of the ant fauna of Madagascar (Hymenoptera: Formicidae)". Journal of Natural History 31 (2): 269–302. doi:10.1080/00222939700770141. 
  4. ^ Perrault, Gérard H. (2004). "Étude morphoanatomique et biométrique du métasoma antérieur des ouvrières. Contribution à la systématique et à la phylogénie des fourmis (Hymenoptera : Formicidae)". Ann. Soc. Entomol. Fr. (in French) 40 (3–4): 291–371. doi:10.1080/00379271.2004.10697428. 
  5. ^ Grimaldi, D; D Agosti; J M Carpenter. "New and Rediscovered Primitive Ants (Hymenoptera: Formicidae) in Cretaceous Amber from New Jersey, and Their Phylogenetic Relationships". American Museum Novitates 3208: 1–43. 
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