Vitsika tenuis 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 : 92-94

Vitsika tenuis Bolton & Fisher sp. n.

(Figs 117-119, Map 161)

WORKER (holotype in parentheses). TL 2.2-2.8 (2.7), HL 0.54-0.62 (0.61), HW 0.46-0.52 (0.50), CI 81-86 (82), SL 0.38-0.44 (0.44), SI 80-88 (88), PW 0.34-0.39 (0.39), WL 0.62-0.74 (0.74) (15 measured).

Eye with 5-6 rows of ommatidia, and with 6-7 ommatidia in the longest row; EL 0.13-0.14 (EL/HW 0.28-0.30). MfL 0.45-0.52 (MfL/HW 0.98-1.00). Dorsal outline of propodeum in profile, from approximate site of metanotal groove to dorsal base of spine, evenly curved or at most with a very low, obtuse angle anteriorly. Propodeal spines in profile usually distinctly downcurved along their length. Degree of curvature of the spines is variable: in most it is striking but in a few it is not as pronounced, and in the very smallest workers it may not be apparent. Diameter of annulus of propodeal spiracle is about equal to the thickness of the propodeal spine at its midlength. Petiole node in profile small, more or less erect with respect to the peduncle, the node not obviously inclined posteriorly; narrowly but bluntly rounded dorsally, and with the anterior and posterior faces converging toward the dorsum. Sculpture of petiole node faint to vestigial laterally, absent from posterior surface. Height of petiole node in posterior view (from midpoint of the dorsal margin of the foramen to the apex) 0.86-0.95 x its maximum width. In dorsal view postpetiole 1.20-1.38 x broader than long; maximum width of postpetiole 0.93-1.15 x the length of a propodeal spine; maximum width of postpetiole 0.82-0.92 x the distance between the apices of the propodeal spines. Length of postpetiole node in profile slightly less than the height of the segment. Disc of postpetiole entirely smooth. Full adult colour yellow.

QUEEN (gyne). Only alates known. HL 0.63-0.66, HW 0.54-0.59, CI 86-89, SL 0.44-0.46, SI 79-82, PW 0.49-0.54, WL 0.90-0.96, maximum width of mesoscutum 0.43-0.50, maximum length of mesoscutum 0.44-0.52, MfL 0.54-0.60 (3 measured). Propodeal spines stouter and relatively a little shorter than in workers, but characteristically downcurved along their length.

MALE: unknown.

Holotype worker, Madagascar: Prov. Antsiranana, Ampasindava, Ambilanivy, 3.9 km. 181° S Ambaliha, 600 m., 13°48'S, 48°10'E, 4-9.iii.2001, sifted litter, rainforest, BLF 3252(33), CASENT0464860 (Fisher et al.) (CASC).

Paratypes. 5 workers and 3 dealate queens, all BLF 3252: workers (31) CASENT0464846, (32) CASENT0464854, two numbered (42) CASENT0484907 and CASENT0464909, and (45) CASENT0464926; queens (32) CASENT0464853, (43) CASENT0464916, and (47) CASENT0464934 (CASC). [The eight paratype specimens have been selected from leaf litter series BLF 3252, which also contains another 14 workers and 5 dealate queens, all in CASC.]

The vast majority of tenuis specimens are instantly recognisable by their strongly downcurved propodeal spines. Some other species have propodeal spines that in profile are shallowly curved or weakly sinuate, but none are downcurved to the extent seen in tenuis . In addition, tenuis is a small yellow species (HW 0.46-0.52), with relatively few ommatidia in the eye, without a marked peak or crest in the propodeal dorsal outline, with an upright petiole node that lacks strong sculpture, and with the disc of the postpetiole smooth.

All material of this species was retrieved from litter samples in rainforest.

Non-paratypic material examined. Madagascar: Prov. Antsiranana, Ampasindava, Ambilanivy (Fisher et al.); Prov. Antsiranana, R.S. Manongarivo, SW Antanambao (B.L. Fisher); Prov. Toamasina, R.S. Ambatovaky (B.L. Fisher et al.); Galoka chain, Mont Galoka (B.L. Fisher et al.).