Cylindromyrmex Mayr, 1870

Borowiec, Marek L., 2016, Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae), ZooKeys 608, pp. 1-280 : 93-97

Taxon classification Animalia Hymenoptera Formicidae

Cylindromyrmex Mayr, 1870

= Holcoponera Cameron, 1891

= Hypocylindromyrmex Wheeler, W. M., 1924a

= Metacylindromyrmex Wheeler, W. M., 1924a

Type-species.

Cylindromyrmex striatus , by monotypy.

Cylindromyrmex is a genus of mostly arboreal-nesting termite hunters, rarely encountered but distributed throughout New World tropics, including the Antilles.

Diagnosis.

Worker. With a combination of large eyes, conspicuously costate or striate sculpture, torulo-posttorular complex horizontal and concealing antennal sockets, two pectinate spurs on mid and hind tibiae, and simple pretarsal claws, the workers of Cylindromyrmex can be readily distinguished from all other dorylines. The only other genus with large eyes, conspicuously sulcate sculpture, and two tibial spurs is Chrysapace , but it has fully exposed antennal sockets, possesses toothed pretarsal claws, and occurs only in the Old World. The extinct Procerapachys , which can also have sulcate sculpturing, has a single pectinate spur on each mid and hind tibiae.

Male. The males of Cylindromyrmex are also easily differentiated from all other genera by two tibial spurs, simple pretarsal claws, no transverse groove on the mesopleuron, and well-developed wing venation with costal (C) vein present in fore wing, two submarginal cells and marginal cell closed. The only other genus with two tibial spurs and similar venation is the Old World genus Chrysapace , but it has a transverse groove on the mesopleuron and pretarsal claws armed with a tooth. Putative males of the extinct Procerapachys have only one spur on each mid and hind tibiae.

Description.

Worker.Head: Antennae with 12 segments. Apical antennal segment moderately enlarged, broader than and about equal in length to two preceding segments combined. Clypeus without cuticular apron. Lateroclypeal teeth absent. Parafrontal ridges absent. Torulo-posttorular complex horizontal. Antennal scrobes present. Labrum with median notch or concavity. Proximal face of stipes projecting beyond inner margin of sclerite, concealing prementum when mouthparts fully closed. Maxillary palps 3- or 2-segmented. Labial palps 2-segmented. Mandibles triangular, with teeth or edentate. Eyes present, always composed of more than 5 ommatidia and usually more than 20 ommatidia. Ocelli present or absent. Head capsule with differentiated vertical posterior surface above occipital foramen. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Posterior head corners dorsolaterally immarginate. Carina surrounding occipital foramen ventrally present. Mesosoma: Pronotal flange separated from collar by distinct ridge or not. Promesonotal connection with Pronotomesopleural suture completely fused. Pronotomesopleural suture visible, unfused up to notal surface. Mesometapleural groove deeply impressed, conspicuous. Transverse groove dividing mesopleuron absent. Pleural endophragmal pit concavity present. Mesosoma dorsolaterally immarginate. Metanotal depression or groove on mesosoma absent. Propodeal spiracle situated low on sclerite. Propodeal declivity with distinct dorsal edge or margin and rectangular in posterior view. Metapleural gland bulla visible or not visible through cuticle. Propodeal lobes present, well developed. Metasoma: Petiole anterodorsally marginate, dorsolaterally immarginate, dorsolaterally marginate, and laterally above spiracle marginate. Helcium in relation to tergosternal Pronotomesopleural suture placed at posttergite and supraaxial. Prora forming a V-shaped protrusion. Spiracle openings of abdominal segments IV–VI circular. Abdominal segment III anterodorsally immarginate and dorsolaterally immarginate. Abdominal segment III more than half size of succeeding segment IV, which is weakly constricted at presegmental portion (uninodal waist). Girdling constriction of segment IV present, i.e. pre- and postsclerites distinct. Cinctus of abdominal segment IV gutter-like, not sculptured. Abdominal segment IV not conspicuously largest segment. Abdominal tergite IV not folding over sternite, and anterior portions of sternite and tergite equally well visible in lateral view. Girdling constriction between pre- and posttergites of abdominal segments V and VI absent. Girdling constriction between pre- and poststernites of abdominal segments V and VI present or absent. Pygidium large, with impressed medial field and armed with modified setae. Hypopygium unarmed. Legs: Mid tibia with two pectinate spurs. Hind tibia with two pectinate spurs. Hind basitarsus not widening distally, circular in cross-section. Posterior flange of hind coxa not produced as raised lamella. Metatibial gland present as oval patch of whitish cuticle. Metabasitarsal gland absent. Hind pretarsal claws simple. Polymorphism: Monomorphic.

Male.Head: Antennae with 13 segments. Clypeus without cuticular apron. Parafrontal ridges absent. Torulo-posttorular complex vertical. Maxillary palps 2-segment ed. Labial palps 3- or 2-segmented. Mandibles triangular, edentate. Ventrolateral margins of head without lamella or ridge extending towards mandibles and beyond carina surrounding occipital foramen. Carina surrounding occipital foramen ventrally present. Mesosoma: Pronotal flange separated from collar by distinct ridge or not separated. Notauli absent or present. Transverse groove dividing mesopleuron absent. Propodeal declivity with distinct dorsal edge or margin. Metapleural gland opening present. Propodeal lobes present. Metasoma: Petiole anterodorsally marginate, dorsolaterally immarginate, and laterally above spiracle marginate. Helcium in relation to tergosternal Pronotomesopleural suture placed at posttergite and supraaxial. Prora forming a U-shaped margin with median ridge. Spiracle openings of abdominal segments IV–VI circular. Abdominal segment III more than half size of succeeding segment IV; latter weakly constricted at presegmental portion (uninodal waist). Girdling constriction of segment IV present, i.e. pre- and postsclerites distinct. Cinctus of abdominal segment IV gutter-like, not sculptured or cross-ribbed. Girdling constriction between pre- and postsclerites of abdominal segments V and VI absent. Abdominal segment IV not conspicuously largest segment. Abdominal sternite VII simple. Abdominal sternite IX distally armed with two spines, with lateral apodemes about as long as medial apodeme, directed anteriorly (towards head). Genitalia: Cupula long relative to rest of genital capsule and shorter ventrally than dorsally. Basimere broadly fused to telomere, with sulcus discernable at junction, and ventrally with left and right arms abutting. Telomere gradually tapering toward apex. Volsella laterally flattened, at apex with dorsal lobe and hooked ventrally. Penisvalva laterally compressed, rounded at apex. Legs: Mid tibia with two pectinate spurs. Hind tibia with two pectinate spurs. Posterior flange of hind coxa not produced as raised lamella. Metatibial gland absent. Metabasitarsal glands absent. Hind pretarsal claws simple. Wings: Tegula present, broad, demiovate in shape. Vein C in fore wing present. Pterostigma broad. Abscissa R·f3 present, running toward distal wing margin and enclosing cell with Rs·f5. Abscissae Rs·f2-3 present, connecting with Rs+M&M·f2. Cross-vein 2r-rs present, differentiated from Rs·f4 by presence of Rs·f2-3. Abscissae Rs·f4-5 differentiated into Rs·f4 and Rs·f5 by 2rs-m. Abscissa M·f2 in fore wing contiguous with Rs+M. Abscissa M·f4 in fore wing present, reaching wing margin. Cross-vein 1m-cu in fore wing present. Cross-vein cu-a in fore wing present, arising from M+Cu and proximal to M·f1. Vein Cu in fore wing present, with both branches Cu1 and Cu2. Vein A in fore wing with abscissae A·f1 and A·f2 present. Vein C in hind wing absent. Vein R in hind wing present, extending past Sc+R but not reaching distal wing margin. Vein Sc+R in hind wing present. Abscissa Rs·f1 in hind wing present, shorter than 1rs-m. Abscissa Rs·f2 in hind wing present, not reaching wing margin. Cross-vein 1rs-m in hind wing fused with M·f1. Vein M+Cu in hind wing present. Abscissa M·f1 in hind wing present. Abscissa M·f2 in hind wing present. Cross-vein cu-a in hind wing present. Vein Cu in hind wing present. Vein A in hind wing with abscissae A·f1 and A·f2 present.

Gyne. Alate, similar to worker except for the mesosoma; known for several species. See descriptions in De Andrade (1998a).

Larva. Not described. Cocoons absent.

Distribution.

Cylindromyrmex is an exclusively Neotropical lineage with ten extant species and three extinct species known from Dominican amber ( De Andrade 1998a). Its distribution extends from the state of Veracruz, Mexico to Rio Grande do Sul in southern Brazil ( De Andrade 1998a, Quiroz-Robledo 2003). Known from Cuba and Hispaniola, Cylindromyrmex darlingtoni is also the only member of the Dorylinae endemic in the Antilles. Cylindromyrmex whymperi has been apparently introduced and established in Galapagos Islands ( De Andrade 1998a).

Taxonomy and phylogeny.

Cylindromyrmex has three generic synonyms: Holcoponera Cameron, Hypocylindromyrmex Wheeler, and Metacylindromyrmex Wheeler. Cameron’s Holcoponera has been considered a synonym since the end of 19th century ( Forel 1892 a), and the two other names were introduced as subgenera by Wheeler (1924a) but have not been used as valid since Brown’s (1975) work on the ' Cerapachyinae '. De Andrade (1998a) revised, illustrated, and keyed all the species of Cylindromyrmex , subsequently adding new records and a second fossil taxon from Dominican amber ( De Andrade 2001).

Cylindromyrmex is the sister genus to Acanthostichus ( Brady et al. 2006, Brady et al. 2014, Borowiec, in prep.). A morphology-based internal phylogeny is also available, inferred by De Andrade (1998a).

Biology.

Members of this lineage have been reported to be termite predators ( De Andrade 1998a). Some authors described Cylindromyrmex as termite inquilines based on records of workers from termite nests ( Wheeler 1936, Overal and Bandeira 1985). It seems possible, however, that these specimens represent raiding foragers of arboreal-nesting ants, as complete nest series containing brood and reproductives are so far known apparently only from wood ( Fernández and Escobar 1997, De Andrade 1998a, Mariano et al. 2004, Philip Ward pers. comm.).

A colony of Cylindromyrmex whymperi has been recently found in Peru and studied in captivity by Josh Richards, an ant keeper from Lima, Peru. He has observed that these ants readily pursue and sting termites, which are brought to the nest paralyzed but apparently not dead. When outnumbered in a confrontation, Cylindromyrmex workers first sting as many termites as possible before attempting to carry some of them back to the nest (Josh Richards pers. comm.).

Gobin et al. (2001) described a novel type of gland between sternites VI and VII in Cylindromyrmex whymperi and demonstrated that this species employs mass recruitment to termite prey. Morgan et al. (2008) chemically analyzed Dufour’s gland secretions of the same species. Three species of Cylindromyrmex ( Cylindromyrmex brasiliensis , Cylindromyrmex brevitarsus and Cylindromyrmex longiceps ) have been reported occurring in sympatry, collected in Malaise traps in a single locality in Bahia, Brazil. The flying males and gynes were present in samples from the end of August to beginning of December, with at least one of the samples containing all the three species ( Delabie and Reis 2000).

All known queens of Cylindromyrmex are winged and brood production is apparently synchronized ( Mariano et al. 2004, Josh Richards pers. comm.).

Species of Cylindromyrmex

† Cylindromyrmex antillanus De Andrade, 1998a: Dominican amber

Cylindromyrmex boliviae Wheeler, W. M., 1924a: Bolivia

Cylindromyrmex brasiliensis Emery, 1901a: Brazil

Cylindromyrmex brevitarsus Santschi, 1925: Brazil

Cylindromyrmex darlingtoni Wheeler, W. M., 1937: Cuba

† Cylindromyrmex electrinus De Andrade, 1998a: Dominican amber

Cylindromyrmex escobari De Andrade, 1998a: Colombia

Cylindromyrmex godmani Forel, 1899: Panama

† Cylindromyrmex inopinatus De Andrade, 2001: Dominican amber

Cylindromyrmex longiceps André, 1892: Brazil

Cylindromyrmex meinerti Forel, 1905: Venezuela

Cylindromyrmex striatus Mayr, 1870: Suriname

Cylindromyrmex whymperi (Cameron, 1891): Ecuador