Liomyrmex

Workers of the single species of this genus are blind and have been found associated with termites. Rarely collected, little is known about their biology (see Liomyrmex gestroi).

Identification
From Rigato and Bolton (2001) - Blind workers with smooth, thick and yellow integument. The legs and antennae are short, and the insect has an elongate, yet robust appearance. The worker caste has the following combination of characters: mandibles short and 4-toothed; bicarinate clypeus; eyes absent; scapus short and somewhat club shaped (similar to that of Vollenhovia); promesonotum flat in profile and without dorsal suture; propodeal spiracle large; propodeum unarmed; bulla of the metapleural gland long and digitiform; petiole and postpetiole massive, the former with a well developed subpetiolar lobe.

Eguchi, Bui and Yamane (2011) - The worker of Liomyrmex is somewhat similar to eyeless worker (or minor) of Anillomyrma, Oligomyrmex, Parvimyrma and Solenopsis. However, frontal lobes are not so widely separated by the posteromedian portion of clypeus and antennal segmentation is not “11-segmented with distinct 3-segmented club” in the worker (minor) of the latter genera.

Distribution
Known from the Indo-Australian and Oriental zoogeographical regions (as defined by Bolton, 1994).

Nomenclature

 *  LIOMYRMEX [Myrmicinae: Liomyrmecini]
 * Liomyrmex Mayr, 1865: 23. Type-species: Myrmica caeca, by monotypy (junior primary homonym; replaced by Laparomyrmex gestroi, first available replacement name: Bolton, 1995b: 248).
 * Liomyrmex senior synonym of Laparomyrmex: Dalla Torre, 1893: 63.
 * Liomyrmex senior synonym of Promyrma: Forel, 1913k: 26.
 * LAPAROMYRMEX [junior synonym of Liomyrmex]
 * Laparomyrmex Emery, 1887b: 461. Type-species: Laparomyrmex gestroi, by monotypy.
 * Laparomyrmex junior synonym of Liomyrmex: Dalla Torre, 1893: 63.
 * PROMYRMA [junior synonym of Liomyrmex]
 * Promyrma Forel, 1912m: 764. Type-species: Promyrma butteli (junior synonym of Laparomyrmex gestroi), by monotypy.
 * Promyrma junior synonym of Liomyrmex: Forel, 1913k: 26; Emery, 1921f: 191.

The generic diagnosis by Rigato and Bolton (2001):

Worker
Monomorphic but size-variable, subterranean, maybe termitophilous (see below), myrmicine ant, with the following combination of characters:

1) Palp formula 2,2.

2) Mandibles with a short, 4-toothed, masticatory margin; the teeth increasing in size from the basalmost to the apical.

3) Clypeus with a distinct, raised median portion, margined at each side by a well defined carina. Clypeus longitudinally arched and widely inserted between the frontal lobes. Anterior c1ypeal margin straight in the middle. Two short, straight, anteriorly directed and slightly converging setae are present, one on each side of the mid point of the anterior margin.

4) Frontal lobes widely separated, convergent anteriorly and parallel posteriorly. Frontal carinae and scrobes absent.

5) Frontal triangle very faintly impressed; hardly visible.

6) Antenna 11-segmented and short, with a well defined 3-merous club. Scape club-shaped in dorsal view; in frontal view it appears somewhat flattened at the apex.

7) Eyes absent.

8) Promesonotum flat and without any trace of suture in dorsal view.

9) Metanotal groove impressed.

10) Propodeum unarmed; broadly arched between the flat dorsum and the moderately convex declivity.

11) Propodeal spiracle large.

12) Propodeal lobes well developed, not protruding posteriorly and continuing the curvature of the propodeal declivity.

13) Metapleural gland present, with a large, elongate, digitiform bulla directed upward and forward.

14) Petiole massive with a short peduncle and a distinct node. The latter is transverse in dorsal view and thick and squarish in profile. A large, flat subpetiolar process is also present.

15) Postpetiole massive, slightly wider than the petiole and with an anteroventrally projecting, but not compressed, sternite.

16) Sting well developed and long.

17) Mid and hind tibia with two small apical spurs. The anterior one (with the leg positioned perpendicularly to the body axis) shorter, smooth and straight; the posterior longer, slightly curved and weakly pectinate.

18) Integument thick and pale, mostly testaceous.

19) Body smooth with very sparse and tiny piligerous (bearing pubescence) pits. Some weak sculpture is present only on the frontal lobes (weak rugulae), peduncle and sternite of the petiole (reticulate), and especially around the metapleural gland (longitudinal fine rugulae).

20) Pubescence very sparse, short and appressed on the body; moderately abundant, long and decumbent on the appendages.

21) Hairs very sparse on the body. Usually there is a single pair of strong, long, tapered and slightly curved macrochetae in the following positions: a) on the clypeus, just outside of the carinae; b) close to the rim of the frontal lobes; c) on the ventral side of the head, quite close to the hypostomal bridge; d) on the pronotum, in front of the humeri; e) close to the posterior corners of the petiolar and postpetiolar nodes. Hairs are also present on the gaster: a pair on the sternites I, II and III; two laterally on the tergite III; the sternite and tergite IV have more than a single pair of hairs.

Queen
Black, much larger than the worker. Mandibles, antennae, legs, pubescence and pilosity about as in the worker. The rest as follows: 1) Clypeus with a median, bicarinate portion which is flat and gradually slopes towards the mandibles.

2) Eyes well developed, close to the middle of the sides of the head.

3) Ocelli small, their distance from one another greater than their maximum diameter.

4) Alitrunk distinctly elongate, a little narrower than the head. Parapsidal furrows weak. Axillae well separated, linked by a narrow strip; but the suture between axillae and scutellum is obliterated in the middle. Propodeum unarmed.

5) Propodeal spiracle of ordinary size: proportionally much smaller than in the worker.

6) Petiole with a very large ventral lobe and a transverse, dorsally flattened node. In dorsal view the latter has posteriorly divergent sides and prominent angles.

7) Postpetiole massive, wider than long; its node is deeply concave anteriorly.

8) Gaster elongate.

9) Integument not so smooth as in the worker. Piligerous pits are a little less sparse and more developed. Such pits are very evident on the katepisternum and on the propodeum. A series of thin rugulae run from the metapleural gland orifice to the posterior portion of the katepisternum.

10) Colour piceous black; mandibles, antennae, anterior margin of the head, and legs from the coxo-trochanteral articulation, ferrugineous.

11) Pubescence as in the worker; but quite abundant on the propodeum.

12) Pilosity sparse as in the worker. A pair of macrochetae occur on the scutellum.

13) Fore wing with closed radial and cubital cells; discoidal cell present and large. cu-a vein interrupted by the vannal fold. Wings appearing somewhat slightly infuscated.

Male
Black, winged and of the size of a large worker. 1) Mandibles short, overlapping and with three well developed teeth at the apical margin.

2) Clypeus with two lateral carinae, which are not so developed as in the female castes. A short transverse sulcus is present posteriorly.

3) Frontal lobes absent, toruli exposed.

4) Frontal triangle recognisable but with confused margins because of the small rugae present in that area.

5) Antenna with 12 segments. Scape short, as long as the second funicular segment. All of the funicular segments, excluding the pedicel, are longer than wide.

6) Eyes large, closer to the mandibles than to the vertex.

7) Ocelli quite large, distance from one another about equal to their maximum diameter.

8) Alitrunk narrow, yet not so elongate as in the queen. Notauli absent, parapsidal furrows present. Axillae separated in dorsal view, although closely approaching in the middle. Scutellum a little bulging in profile.

9) Propodeum obtusely tubercled at both sides between the dorsum and the declivity.

10) Propodeal spiracle relatively small.

11) Legs long and slender.

12) Petiole in profile with a rounded, triangular node.

13) Postpetiole distinctly wider than the petiole.

14) Gaster relatively small.

15) Fore wing with the same venation as in the queen; yet it is relatively distinctly shorter and wider and the radial cell appears open. Wings hyaline.

16) Pilosity (but see below) and pubescence sparse as in the females.

17) Sculpture more developed than in females. The head is mostly longitudinally rugulose and sublucid. The upper frons and vertex are finely reticulate punctate and nearly matt. Rest of the body smooth with a feebly developed reticulated sculpture. Side of the alitrunk with a stronger reticulum. Axillae and scutellum strongly, somewhat longitudinally, reticulate and subopaque; also, the scutellum has some distinct, although not deep, punctures.

18) Colour black. Mandibles and appendages brown.