Ishakidris ascitaspis

The single known specimen of Ishakidris ascitaspis was recovered from a Winkler bag sample of previously sieved leaf litter collected at Camp 5 in Gunong Mulu National Park during the Royal Geographical Society expedition there in 1978. Camp 5 lay beside the Melinau River in lowland rainforest at the edge of the limestone outcrop which slopes up to the spectacular Limestone Pinnacles of the park. (Bolton 1984)

Identification
Bolton (1984) - Diagnostic characters which in combination isolate Ishakidris from the workers of all other myrmicine ant genera are as follows.

1. Form and dentition of the massive mandibles

2. Palp formula 2,2.

3. Labrum anteriorly with a pair of elongate digitate lobes.

4. Antennae with 9 segments, the two apical segments forming a strongly defined club.

5. Antennal scrobes deep and extensive, the eye situated ventrolaterally within the scrobal area.

6. Head shield-like, the frontal carinae very widely separated and greatly expanded anteriorly and laterally.

7. Frontal carinae flanking lateral portions of clypeus and forming the anterolateral corners of the head.

8. Mesopleural presumed glandular area present, with subtending open groove.

9. Petiole and postpetiole lacking spongiform or lamellate appendages.

10. Massive longitudinal basal carina present on first gastral sternite.

Distribution
Malaysia: Sarawak

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia.

Castes
Known from a single worker.

Nomenclature

 *  ascitaspis. Ishakidris ascitaspis Bolton, 1984: 375, figs. 1-4 (w.) BORNEO.

Description
Holotype TL 4.2, HL 1.14, HW 1.06, CI 93, ML 0.18, MI 16, SL 0.52, SI 49, PW 0.50, AL 1.00 (measurements in millimetres, as defined in Bolton, 1983).

Mandibles longitudinally costulate-rugose, with punctures between the longitudinal components, the mandibles more densely sculptured than any other part of the body. Dentition of apical (masticatory) margins partially obscured by a mesially directed row of yellowish hairs which arise at the base of the tooth-row down the length of the margin. Counting from the base of the mandible the first (=basal), third and fifth teeth are approximately the same length (c. 0.10) and are the largest teeth on the margin; teeth 2, 4 and 7 are about the same size (c. 0.08); teeth 8 and 10 are reduced to denticles whilst 6, 9 and 11 (preapical) are intermediate in size between 5 and 7; the apical tooth (12) is sharply pointed and is only slightly smaller than teeth 2 , 4 and 7. Outer margins of mandibles straight to shallowly concave when the blades are viewed so that the entire dental row is visible, basally passing through a narrow blunt curve to their insertions. Mandibles with fine appressed short hairs, the ventral margin on each side with a single very long fine hair close to the articulation; this is most probably a mandibular trigger hair. Anteromedian margin of labrum with a pair of elongate narrow digitate lobes which are fringed by narrow lanceolate hairs. Apices of lobes dorsally apparently with a fused mass of very fine hairs, but this may be an artefact. Dorsum of clypeus and of head proper mostly smooth, with minute shallow widely scattered punctures from which tiny inconspicuous appressed hairs arise. On the clypeus these tiny hairs are directed towards the anterior margin; on the anterior half of the head they are directed towards the midline and on the posterior half they are directed towards the highest point of the vertex. The semitranslucent expanded portions of the frontal carinae are longitudinally finely arched-costulate, some of the costulae extending on to the head proper on each side of the median convexity. Sides of head behind level of frontal carinae with 3 pairs of short acute laterally projecting hairs, otherwise the cephalic dorsum without standing pilosity of any description. Occipital margin bounded by a low but sharply defined carina which ends in a pair of translucent cuticular flanges or lugs running down the posterolateral occipital lobes. Ventrally these lugs are confluent with the ventrolateral longitudinal carinae which run forwards to the bases of the mandibles. Eyes small, with only 7 -8 ommatidia, the maximum diameter 0.06 (c. 0.06 ~ HW). Sides of head between eye and mandibular base finely irregularly rugulose with roughened to punctulate spaces between the rugulae. Above the eye the rugulae fading out and behind the eye the sides of the head mostly smooth. A secondary longitudinal rugule or weak carina runs from near the mandibular base to a point well behind the level of the eye, and is situated between the eye and the carinate ventrolateral cephalic margin. Bulging convex ventral surface of head smooth and shining. Antennal scapes and funiculi clothed with decumbent or appressed narrowly spatulate hairs. With the alitrunk in dorsal view the humeri rounded, the lateral marginations darker in colour than the dorsum proper, the surface lacking standing hairs except for a single pair on the transverse ridge separating the mesonotum and propodeum. A narrow arcuate ridge between the propodeal spines separates the dorsum from the declivity. Dorsum of alitrunk mostly unsculptured, with one or two faint longitudinal rugulae on each side of the mesonotum which run forward on to the posterior pronotum. Both pronotum and mesonotum with a few scattered minute appressed hairs arising from shallow pits, as on the head. Anteromedially the pronotum with a very short low carina. Propodeal declivity between the infradental lamellae exceedingly finely punctulate. Sides of alitrunk glossy and smooth, the propodeal infradental lamellae showing an internal fine reticular patterning. Petiole with sides and dorsum of node rugose, the rugae less well defined dorsally than laterally. Laminar ventral crest of petiole reticulate-punctate as is the area below the level of the spiracle. Dorsum of petiole node with one anterior and two posterior pairs of short narrowly spatulate hairs, and with another pair posterolaterally. On the postpetiole there is a similar pair of hairs anterodorsally, two pairs posterodorsally and two pairs laterally. Petiole node in dorsal view longer than broad, broadening from front to back; postpetiole broader than long, subrectangular, margined by thick rugae anteriorly and laterally and with a more dorsally situated pair of longitudinal rugae which weakly converge posteriorly. Laterosternites of postpetiole densely punctate. First gastral tergite finely superficially reticulate everywhere, without pilosity and with a few short but sharply defined basal costulae arising from the slightly thickened basal margin. First gastral sternite smooth and convex, the broad basal carina thin-walled and translucent close to the base of the sclerite; the true basal surface of the sternite concave and thickly sclerotized below the postpetiole. Apex of gaster with a few inconspicuous projecting hairs. Femora and tibiae of middle and hind legs with appressed narrowly spatulate hairs. Colour of head, alitrunk and pedicel segments glossy medium brown to reddish brown, the frontal carinae, antennae, legs and gaster lighter brown to yellowish brown. Mandibles darker in colour than head-shield; marginations of head ventrolaterally and of alitrunk laterally blackish.

Type Material
Holotype worker, East Malaysia: Sarawak, 4th Division, Gunong Mulu National Park, v-viii.1978, litter sample Camp (P. M. Hamrnond & J. E. Marshall).

The holotype is damaged, lacking its left middle and hind legs which were missing on collection.