Malagidris jugum

M. jugum nests in the ground and forages in the leaf litter, in rotten wood and on the surface of the ground; it has been recovered from litter samples and pitfall traps. The species also ascends low vegetation and workers have been discovered investigating Malaise traps. Most collection records are from tropical dry forest, but jugum also occurs in rainforest and littoral forest.

Identification
The worker of this large, slender, relatively heavily sculptured species most closely resembles Malagidris alperti in terms of habitus, relative dimensions and mesosomal sculpture. The main differences between them include the profile shape of the clypeus, indentation of the cephalic dorsum, and aspects of the pilosity. (Bolton and Fisher 2014)


 * Key to Eutetramorium group genera

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  jugum. Malagidris jugum Bolton & Fisher, 2014: 28, figs. 22-24, Map 130 (w.eq.m.) MADAGASCAR.

Unassociated male. Two specimens (CASENT0085227 and CASENT0085227-D01) (one badly damaged) are present in CASC (Madagascar: Prov. Antsiranana, P.N. Montaigne d’Ambre, MA-01-01D-04 (E.R. Harin’Hala)), that appear close to jugum but are specifically distinct. They contrast to the male of jugum as follows. Mandible with 8–9 sharp teeth. CI 84, SI 42, MfL 1.10. First funicular segment of antenna 0.40 times the length of the second segment. EL/HW 0.48. Peduncle of petiole with spiracles borne on tubercles, in dorsal view the tubercles large and strongly prominent, the width across them is greater than the width across the node. Postpetiole in dorsal view shorter and broader, 1.25 × longer than broad.

It is most likely that these two males represent a species whose worker remains undiscovered, but it is also possible that jugum, as presently envisaged, consists of two unrecognised siblings. A final, but much less probable, situation is that the males represent a socially parasitic form, but they show no characters attributable to the “inquiline syndrome.”

Worker
(holotype in parentheses). TL 5.5–7.7 (6.6), HL 1.30–1.56 (1.46), HW 0.86–1.12 (1.00), CI 66–73 (68), SL 1.55–1.98 (1.74), SI 164–192 (174), PW 0.73–0.98 (0.85), WL 1.86–2.28 (2.04) (20 measured).

Mandible with 10–13 teeth and denticles in total, finely longitudinally costulate. Median clypeal seta stout, in dorsal view usually arising from a small tubercle at the midpoint of a false anterior margin (tubercle may be effaced in smallest workers); below the seta there is a short, vertical or reflexed section of the clypeus that descends to the true anterior margin. In profile the clypeal setae appear to arise from a ridge that is well above the true anterior margin of the clypeus. Scapes long (SI > 160), with minute pubescence but lacking standing setae. Club segments of funiculus long and slender, distinctly longer than broad. EL 0.22–0.28 (EL/HW 0.24–0.26). With head in profile the dorsal outline above and behind the eye is more or less flat, or at most only extremely shallowly concave. With head in full-face view, sides behind the eyes elongate, shallowly convex and weakly convergent posteriorly, passing into the posterior margin through a short angle; posterior margin shallowly concave and the occipital carina raised into a translucent cuticular flange that is widest medially. Dorsum of head predominantly longitudinally rugose, with occasional anastomoses; posteriorly the rugae decreasing in strength and the number of anastomoses increasing. Spaces between the rugae finely punctulate, especially on the anterior half. Ventral surface of head with shallow, arched transverse costulae. Dorsum of mesosoma sharply rugose, the strongest rugae transverse; with some reticulation on the pronotum; spaces between the rugae mostly smooth, not reticulate-punctulate. In dorsal view the lower sides of the pronotum flared outward above the coxal articulations, so that the maximum pronotal width, across the flared portion, is 1.25–1.30 times greater than across the humeri. Propodeal spines long in profile (0.45–0.60). Propodeal declivity unsculptured, or at most with a vestige of transverse sculpture between the bases of the spines. Side of mesosoma rugose to reticulate-rugose. Metafemur long and slender, MfL 2.04–2.76 (MfL/HW 2.17–2.65, MfL/MfH 7.27–8.92). Peduncle of petiole long and slender, downcurved in profile and with a small, dentiform anteroventral process. Subpetiolar process not followed by a cuticular crest along the mid-ventral surface of the peduncle. Petiole node in profile narrowly conical, vertical to slightly inclined anteriorly; acute apically. In posterior view the sides of the petiole node approximately parallel in their lower halves, but in their upper halves convergent dorsally to a rounded apex that is usually narrowly rounded in larger, more broadly rounded in smaller, individuals. Petiole node with faint superficial punctulate sculpture, almost effaced in some. Postpetiole in profile shallowly convex dorsally, about 1.35–1.57 times longer than high; in dorsal view distinctly longer than broad; maximum dorsal width of postpetiole ca 0.36–0.43, about equal to its height. Dorsum of postpetiole node finely punctulate and with a few weak superficial rugulae. Base of first gastral tergite usually with short but obvious basigastral costulae, effaced in smaller workers; tergite otherwise unsculptured.

Pilosity: with head in full-face view the side in front of the eye with 0–1 projecting setae, the side behind the eye with 0–3 (usually 1) projecting setae, without setae that project outward from below the eye itself; with head in profile the dorsum behind the highest point with 3–4 pairs of setae that are inclined anteriorly, followed by a transverse row of 4–6 setae closest to the posterior margin (extremely rarely this row reduced to a single widely separated pair); pronotal dorsum with a 0–2 pairs of setae, when 2 pairs present one is at the humeri, the other is very close to the mesonotal junction, a count of 0 may be the result of abrasion; mesonotum usually with 1 pair anteriorly, but rarely a second, more posterior pair present, no setae at the metanotal groove; propodeal dorsum without setae; ventral surface of metafemur with 0–1 setae, when present close to the metatrochanter; petiole node with a pair of setae on its posterior face; postpetiole with 1–2 pairs of setae dorsally and with a transverse row of 4 posteriorly; gaster with numerous simple setae. Most of the differences in pilosity are the result of normal variation, but some may be due to abrasion. Full adult colour yellowish brown to brown.

Queen
(gyne). Ergatoid. TL 6.7, HL 1.34, HW 0.99, CI 74, SL 1.40, SI 141, WL 1.92, MfL 1.86, MfL/HW 1.88, MfL/MfH 6.64. EL 0.25 (EL/HW 0.25) (1 measured). Propodeal spine length 0.44, but the spines stouter than in the worker. Postpetiole length 0.56, width 0.59, height 0.59. Most dimensions are within the worker ranges, but the scape is relatively shorter, the metafemur is both absolutely and relatively shorter, and is somewhat deeper in posterior view. In general the ergatoid matches the worker description, but the pronotal sculpture is more sharply reticulate-rugose, and the humeral angles are more pronounced. Pilosity as worker but head without the posterior transverse row (this may have been abraded away in the single specimen available). Ocelli are absent.

Male
Mandible with 9–11 sharp teeth. CI 75–76, SI 45–48, MfL 1.80–1.90 (2 measured). First funicular segment of antenna less than 0.50 times the length of the second segment. EL/HW 0.44–0.45. With head in profile the dorsal outline behind the posterior ocelli slopes down gradually to the occipital carina, the surface not vertical immediately behind the ocelli. With mesosoma in dorsal view the pronotum forms a visible anterior arc in front of the mesoscutum. Notauli absent. Peduncle of petiole with spiracles borne on tubercles, in dorsal view the tubercles large and strongly prominent, the distance across them distinctly greater than the width of the node. Postpetiole in dorsal view long and narrow, 1.94–2.06 × longer than broad.

Type Material
Holotype worker, Madagascar: Antsiranana, Rés. Analamerana, 28.4 km. 99° Anivorano Nord, 12°44.80’S, 49°29.69’E, 60 m., 5–7.xii.2004, tropical dry forest, BLF 11400 (8), CASENT0054119, (B.L. Fisher). Paratypes. 5 workers with same data as holotype, but coded: BLF 11400 (9), CASENT0054164; BLF 11400 (10), CASENT0054165; BLF 11400 (11), CASENT0054167; BLF 11400 (LO), CASENT0054168; BLF 11400 (25), CASENT0054121 (CASC, )

References based on Global Ant Biodiversity Informatics

 * Bolton B., and B. L. Fisher. 2014. The Madagascan endemic myrmicine ants related to Eutetramorium (Hymenoptera: Formicidae): taxonomy of the genera Eutetramorium Emery, Malagidris nom. n., Myrmisaraka gen. n., Royidris gen. n., and Vitsika gen. n. Zootaxa 3791(1): 1-99.
 * Goodman S., Y. Anbdou, Y. Andriamiarantsoa, B. L. Fisher, O. Griffiths, B. Keitt, J. J. Rafanomezantsoa, E. Rajoelison, J. C. Rakotonirina, L. Ranaivoarisoa et al. 2017. Results of a biological inventory of the Nosy Ankao island group, Parc National de Loky-Manambato, northeastern Madagascar. Malagasy Nature, Association Vahatra, 2017, 11, 