Cryptopone

Cryptopone is a moderately large genus (25 described species and subspecies) with a cosmopolitan distribution, though the species diversity is centered in Asia. Cryptopone workers are well-adapted to a hypogeic lifestyle, with small body size, reduced or absent eyes, flattened scapes, and traction setae on the mesotibiae.

Identification
Schmidt and Shattuck (2014) - Cryptopone workers lack any obvious autapomorphic characters, but can be identified by the following characters (in combination): mandibles usually with a basal pit or fovea (absent in members of the former genus Wadeura, here newly synonymized with Cryptopone), frontal lobes small and closely approximated, scapes flattened, eyes vestigial to absent, propodeum with a distinct dorsal face which widens posteriorly, metabasitarsus with simple setae but lacking spiniform or peg-like traction setae, and mesotibiae with stout traction setae (sometimes small and reduced to a few, but always present). Workers of Cryptopone most closely resemble those of Pseudoponera (a close relative of Cryptopone), but differ most consistently in the presence of mesotibial traction setae. Similar traction setae occur in Centromyrmex, Feroponera, Promyopias, and Buniapone, but these genera all lack at least some portion of the Diagnosis given above. Several other ponerine genera have basal mandibular pits, including Brachyponera, Euponera, and Hagensia, but these genera all lack mesotibial traction setae and have larger eyes, among many other differences.

Distribution
Cryptopone has a virtually cosmopolitan distribution, occurring in every major biogeographic region, though the species diversity is centered in East and Southeast Asia (Brown, 1963; Bolton et al., 2006).

Biology
Schmidt and Shattuck (2014) - Very little is known about the habits of Cryptopone, but based on morphology and anecdotal observations they are clearly hypogeic (e.g., Wheeler & Gaige, 1920). Cryptopone workers exhibit many classic characters of hypogeic ants, including small size, depigmentation, flattened scapes, vestigial eyes, and traction setae on the mesotibiae (e.g., Wheeler, 1933a). Reported field observations and collection data indicate that Cryptopone species nest in a diversity of microhabitats including rotting wood, polypore fungi, under grass, in leaf litter, in soil, or even inside termitaria (Creighton & Tulloch, 1930; Forel, cited by Wheeler, 1933a; Smith, 1934; Weber, 1939; Wilson, 1958c; Terayama, 1999; Radchenko, 2005; Longino, 2013). Workers have been observed foraging in soil, leaf litter, and under moss or rocks (Wheeler & Gaige, 1920; Wilson, 1958c; Radchenko, 2005; Longino, 2013). Haskins (1931) observed workers of Cryptopone gilva in laboratory conditions foraging in exposed conditions for brief periods, suggesting that they are not strictly hypogeic. Wilson (1958c) reported that workers of Cryptopone butteli are timid and slow moving, and Wheeler & Gaige (1920) noted similar behavior in workers of C. gilva and observed that they feign death; Smith (1934) also noted sluggish behavior in C. gilva. Cryptopone are most likely generalist predators, though observations of Cryptopone food preferences are scant. Imai et al. (2003) reported that Cryptopone sauteri is a predator of beetle and fly larvae.

Almost nothing is known about the social organization of Cryptopone, but colonies are typically small (C. butteli: Wilson, 1958c; Cryptopone guianensis: Weber, 1939). Creighton & Tulloch (1930) observed a single colony of C. gilva with five dealate queens and stated that its colonies are small, and Smith (1934) similarly observed polygynous colonies of C. gilva but noted that its colonies could have as many as several hundred workers. Haskins (1931) also reported frequent polygyny in C. gilva. Nest emigrations are facilitated by social carrying in C. gilva (Haskins, 1931). Haskins (1931) gives many additional details of the habits of C. gilva, including the results of interesting experiments on its visual and auditory acuity.

Fernandes and Delabie (2019) Neotropical Cryptopone - All the Neotropical species of Cryptopone seem almost strictly cryptobiotic, but in rare cases, as already observed for Cryptopone gilva (Haskins 1931) and here for Cryptopone holmgreni, workers can forage for short periods on the ground. The Macoupa (French Guiana) specimens of C. holmgreni were found in soil samples (TSBF traps) during earthworm diversity studies. Although Cryptopone species are always rare and we have no natural history details about this series of specimens, the Macoupa material suggests that two species (Cryptopone guianensis and C. holmgreni) can live in sympatry. Due to its cryptobiotic habits, Cryptopone presents an important morphological convergence (mesotibial spiniform setae, Figure 2B-D) with several other Ponerinae genera (Feroponera, Promyopias, Buniapone and, especially, Centromyrmex). These setae seem well adapted to allow rapid circulation in narrow tunnels built by earthworms and other underground organisms, as any movement of the legs in contact with the oblique walls would facilitate ant locomotion. Furthermore, the morphological convergence with Centromyrmex suggests that some species of Cryptopone could be specialist predators of termites living in the ground (Delabie et al. 2000), including C. holmgreni.

Nomenclature

 *  CRYPTOPONE  [Ponerinae: Ponerini]
 * Cryptopone Emery, 1893a: cclxxv. Type-species: Cryptopone testacea, by monotypy.
 * [Cryptopone also described as new by Emery, 1893f: 240. Type-species not Amblyopone testacea, unjustified subsequent designation by Wheeler, W.M. 1911f: 161, repeated in Emery, 1911d: 88, Wheeler, W.M. 1922a: 780, Donisthorpe, 1943f: 636, Kempf, 1972a: 90 and Taylor & Brown, D.R. 1985: 28; see discussion in Wilson, 1958d: 360.]
 * Cryptopone junior synonym of Pachycondyla: Mackay & Mackay, 2010: 3.
 * Cryptopone revived from synonymy: Schmidt & Shattuck, 2014: 182.
 * Cryptopone senior synonym of Wadeura: Schmidt & Shattuck, 2014: 182.
 * WADEURA [junior synonym of Cryptopone]
 * Wadeura Weber, 1939a: 102. Type-species: Wadeura guianensis, by original designation.
 * Wadeura junior synonym of Pachycondyla: Snelling, R.R. 1981: 389; Hölldobler & Wilson, 1990: 11; Brown, in Bolton, 1994: 164.
 * Wadeura junior synonym of Cryptopone: Schmidt & Shattuck, 2014: 182.

Description
Schmidt and Shattuck (2014):

Worker
Very small to medium sized (TL 1.7–6.1 mm) ants with the standard characters of Ponerini. Mandibles triangular to subfalcate, usually with a small basal pit (absent in Wadeura) and without a basal groove. Anterior margin of clypeus broadly convex. Frontal lobes small and closely approximated. Scapes flattened. Apical segments of antennal funiculus often distinctly clubbed. Eyes greatly reduced or absent (in Wadeura). Metanotal groove reduced to a suture. Propodeum with a distinct dorsal face which widens posteriorly. Propodeal spiracles round to ovoid. Mesotibiae armed with stout traction setae. Metatibial spur formula (1p) or (1p, 1s). Petiole surmounted by a thick scale, its posterior face convex in dorsal view. Helcium sometimes projecting from near midheight of the anterior face of A3. Gaster with a moderate girdling constriction between pre- and postsclerites of A4. Head and body finely punctate, with some smooth and shining areas on the sides of the mesosoma, and with scattered to abundant short pilosity and dense pubescence. Color usually testaceous to orange, rarely black.

Queen
Similar to worker but slightly larger, alate, with ocelli and larger eyes, and with the other thoracic modifications typical of alate ponerine queens (Brown, 1963). See additional details in Ogata (1987).

Male
See descriptions by Brown (1963) and Ogata (1987).

Larva
Described for various species by Wheeler & Wheeler (1952, 1971a, 1986b).