Malagidris dulcis Bolton & Fisher

Bolton, Barry & Fisher, Brian, 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), pp. 1-99 : 24-26

Malagidris dulcis Bolton & Fisher sp. n.

(Figs 16-18, Map 128)

WORKER (holotype in parentheses). TL 4.7-5.4 (5.3), HL 1.04-1.28 (1.20), HW 0.75-0.90 (0.82), CI 68-74 (68), SL 1.12-1.38 (1.28), SI 147-160 (156), PW 0.62-0.75 (0.66), WL 1.40-1.70 (1.58) (10 measured).

Mandible with 10-12 teeth and denticles in total, finely longitudinally costulate. Scapes relatively short (SI 145-160), with minute pubescence but lacking standing setae. Club segments of funiculus long and slender, distinctly longer than broad. EL 0.20-0.25 (EL/HW 0.26-0.30). 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; posterior margin very shallowly concave, with a sharp occipital carina that is not raised into a translucent cuticular flange. Dorsum of head predominantly longitudinally rugulose, anastomoses absent or very sparse; posteriorly the rugulae decrease in strength. Spaces between the rugae finely reticulate-punctulate everywhere. Ventral surface of head with very weak, oblique transverse sculpture. Dorsum of mesosoma rugulose to reticulate-rugulose; spaces between the rugulae with weak punctulate ground-sculpture. Propodeal spines in profile variable in length (0.18-0.26) and degree of elevation. In the majority of specimens the spines short, stout and upcurved, with their ventral margins shallowly convex and dorsal margins shallowly concave; in others the spines are more or less straight. Propodeal declivity unsculptured. Side of mesosoma usually with scattered rugulae, but in some these are very reduced; superficial punctulae are present between the rugulae. Metafemur relatively short, MfL 1.28-1.58 (MfL/HW 1.70-1.83), relatively deep in posterior view, MfL/ MfH 4.60-5.10. Peduncle of petiole slender, more or less straight to extremely feebly 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 quite broad, bluntly rounded dorsally, not acute apically. Petiole node with very weak superficial punctulate sculpture, almost effaced in some. Postpetiole in profile shallowly convex dorsally, about 1.19-1.26 times longer than high; in dorsal view distinctly longer than broad; maximum dorsal width of postpetiole ca 0.34-0.43, about equal to its height. Dorsum of postpetiole node finely punctulate. Base of first gastral tergite usually with basigastral costulae effaced, but sometimes vestiges are visible; tergite otherwise unsculptured. Full adult colour yellow to yellow-brown.

Pilosity: with head in full-face view the side in front of the eye with 1-2 projecting setae, the side behind the eye with 4-5 projecting setae, and also with 1-2 setae that project outward from below the eye itself; with head in profile the dorsum behind the highest point with 4-5 pairs of setae that are inclined anteriorly, followed by a transverse row of 4-6 setae closest to the posterior margin; pronotal dorsum with a transverse row of 4 setae anteriorly and 1-2 pairs close to the mesonotal margin; mesonotum with 4 pairs, the posteriormost of which is at the metanotal groove; propodeal dorsum with 1 pair, uncommonly with a second pair also present; ventral surface of metafemur with 1-2 setae, located close to the metatrochanter; petiole node with a pair of setae on its dorsum, another on its posterior face, and another posterobasally; postpetiole with 4-6 setae dorsally and with a row of 4-6 posteriorly; gaster with numerous simple setae.

QUEEN (gyne): unknown.

PUTATIVE MALE. Mandible with 6-7 sharp teeth. CI 80, SI 58, MfL 1.10 (1 measured). First funicular segment of antenna 0.55 x the length of the second segment. EL/HW 0.50. With head in profile the dorsal outline behind the posterior ocelli descends vertically to the occipital carina, without a posteriorly projecting prominence or lobe behind the vertical surface. With mesosoma in dorsal view the arc of the pronotum is concealed medially by the anterior bulge of the mesoscutum. Notauli with anterior portions discernible, but shallow and almost effaced. Peduncle of petiole with spiracles not borne on tubercles, in dorsal view the maximum width of the petiole is across the node. Postpetiole in dorsal view 1.39 x longer than broad.

Based on a single male (CASENT0135071), Madagascar: Toamasina, P.N. Andrasibe, BLF 19394 (Fisher et al.) (CASC). Tentatively associated with the workers of dulcis as the structure of head and mesosoma in the male is very similar to the male of belti , the species whose workers most closely resemble those of dulcis .

Holotype worker, Madagascar: Antsiranana, Ampombofofo, 25 m., 12.09949°S, 49.33874°E, 21-22.xi.2007, littoral forest, BLF 18541(8), CASENT0141811 (Fisher et al.) (CASC).

Paratypes. 6 workers with same data as holotype, but coded: BLF 18541 (1), CASENT0141806; BLF 18541 (2), CASENT0141807; BLF 18541 (4), CASENT0141808; BLF 18541 (6), CASENT0141809; BLF 18541 (7), CASENT0141810; BLF 18541 (9), CASENT0141812 (CASC, BMNH).

Apart from M. belti , which has a much broader head, shorter scape, and shorter metafemur (CI> 80, SI <130, MfL/HW <1.50), the worker of dulcis is the most setose species of the genus. Its possession of the cephalic setal array described above, combined with 4 mesonotal pairs, including one at the metanotal groove, and at least one pair on the propodeum, render it immediately recognisable. In addition, it is the only species to have the metafemur relatively deep (MfL/MfH 4.60-5.10), a ratio matched only by belti (MfL/MfH 4.62-5.22), and far below those seen in the more attenuated species of the genus, where the collective MfL/MfH is 5.77 to> 12.00.

There is a possibility that dulcis , as presently constituted, includes more than one cryptic species. Of special interest is the variation seen in the degree of elevation of the propodeal spines, and also their length. In terms of elevation the spine in profile varies from about 45° to almost vertical. At present this is not being treated as significant, but the acquisition of more material may necessitate a re-examination. Whatever the elevation of the spine, most specimens have a propodeal spine length of 0.18-0.26. However, there is a single specimen in CASC, collected by P.S. Ward and with collection data noted below, which has a propodeal spine length of 0.38, well above the usual range. This specimen also has a slightly broader head (CI 74), slightly shorter scape (SI 145), deeper metafemur (MfL/MfH 5.50) and a broader postpetiole (length/height ratio 1.05) than is usual. As only one such specimen is available, and because its other characters match the dulcis material, it is retained within dulcis , but this should be re-assessed if similar material is ever rediscovered.

M. dulcis occurs under stones and in leaf litter samples in rainforest. It has also been discovered in littoral forest, and once in tropical dry forest where it was foraging on the ground.

Non-paratypic material examined. Madagascar: Prov. Antsiranana, Foret Andavakoera, ENE Amilobe (Fisher et al.); Prov. Antsiranana, Foret d’Ampombofofo (Fisher et al.); Prov. Antsiranana, Res. Ankarana, SE Matsaborimanga, PSW11031, CASENT0192051 (P.S. Ward).