Vitsika obscura Bolton & Fisher, sp. n.
Creators: name: Bolton, Barry
name: Fisher, Brian
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Vitsika
Vitsika obscura

description: Vitsika obscura Bolton & Fisher sp. n.
(Figs 108-110, Map 158)
WORKER (holotype in parentheses). TL 4.1 (4.1), HL 0.91-0.92 (0.91), HW 0.75-0.78 (0.75), CI 82-85 (82), SL 0.68-0.69 (0.69), SI 88-92 (92), PW 0.59-0.61 (0.59), WL 1.20-1.22 (1.20) (4 measured).
Eye with 9 rows of ommatidia, and with 10-11 ommatidia in the longest row; EL 0.20-0.23 (EL/HW 0.27-0.29). MfL 0.86-0.88 (MfL/HW 1.11-1.16). Antennal scape yellow, distinctly lighter in shade than the brown head capsule. In profile, the dorsal outline of the propodeum with a short, horizontal plateau immediately behind the mesonotal-propodeal junction that then slopes down to the upper base of the propodeal spine, without a distinct peak in its outline posterior to the mesonotal-propodeal junction. Propodeal declivity with 3-4 distinct transverse costulae. Diameter of annulus of propodeal spiracle about equal to the thickness of the propodeal spine at its midlength. Petiole node in profile highest at the anterodorsal angle, the short dorsal surface grades imperceptably into the posterior face. In posterior view the dorsal margin of the petiole node evenly shallowly convex, or almost flat medially. Sculpture of petiole node weak to vestigial laterally; posterior surface of petiole node mostly smooth, but with some sculptural remnants immediately above the foramen. Height of petiole node in posterior view (from midpoint of the dorsal margin of the foramen to the apex) 0.78-0.92 x its maximum width. In dorsal view postpetiole 1.25-1.36 x broader than long; maximum width of postpetiole ca 0.95-1.06 x the length of a propodeal spine; maximum width of postpetiole 0.90-1.00 x the distance between the apices of the propodeal spines. Postpetiole node in profile relatively short and high, its dorsum distinctly convex; the length of the node in profile is visibly greater than the height of the segment. Dorsum of postpetiole node smooth. The main suberect setae on the dorsal (outer) surface of the metatibia are all about the same length, and distinctly shorter than the maximum tibial width. Full adult colour brown to dark brown.
QUEEN (gyne) and MALE: unknown.
Holotype worker, Madagascar: 38 km. S Ambalavao [Prov. Fianarantsoa], Res. Andringitra, 22°12'S, 46°58'E, 1680 m., 23.x.1993, sifted litter (leaf mold, rotten wood), montane rainforest, BLF 820(10)-3, CASENT0192019 (B.L. Fisher) (CASC).
Paratype. 1 worker with same data as holotype but BLF 820(16)-2, no CASENT number (CASC).
This species is described as separate from miranda with some reservations. Only four specimens of obscura are known, but they are consistently larger and lighter in colour than miranda, and have fewer but more widely spaced longitudinal costulae on the mesopleuron. Both miranda and obscura are similar to the yellow astuta, but in that species some of the suberect setae on the dorsal (outer) surface of the metatibia are long and fine, at least as long as the maximum tibial width. In miranda and obscura all suberect setae on the dorsal (outer) metatibial surface are distinctly shorter than the width of the metatibia, and have a uniform, stubbly appearance.
V. obscura has been found in a litter sample and by beating low vegetation.
Non-paratypic material examined. Madagascar: Prov. Fianarantsoa, SSW Ambositra, Ankazomivady (B.L. Fisher).
description: Published as part of 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 .., pp. 1-99 in Zootaxa 3791 (1) on pages 87-89, DOI: 10.11646/zootaxa.3791.1.1