Nanometa forsteri, Álvarez-Padilla & Kallal & Hormiga, 2020

Álvarez-Padilla, Fernando, Kallal, Robert J. & Hormiga, Gustavo, 2020, Taxonomy And Phylogenetics Of Nanometinae And Other Australasian Orb-Weaving Spiders (Araneae: Tetragnathidae), Bulletin of the American Museum of Natural History 2020 (438), pp. 1-107 : 1-107

Nanometa forsteri , sp. nov.

Figures 34–37

TYPE MATERIAL: Male holotype and female allotype from New Zealand, South Island, Arthur’s Pass National Park, Bridal Veil Track, 42° 55′ 49.6″ S, 171° 33′ 43.4″ E, 819 m. 4–5 February 2012, G. Hormiga, N. Scharff, J. Pedersen, voucher code GH1139. Both deposited at MONZ.

DIAGNOSIS: Nanometa forsteri can be differentiated by the following combination of characters: eyes arranged in two lines and subequal in size, with juxtaposed lateral eyes (figs. 36A, G, H). Males of N. forsteri can be distinguished from other small Nanometa species by having the CEBP apophysis longer than this process (figs. 34A–D, 35A–C), and from N. gentilis in particular by having this apophysis with its tip bent posteriorly. Both Nanometa forsteri and N. gentilis have conductor tips C-shaped, but in N. forsteri the basal apophysis is wider and with a blunt tip (figs. 34A, B, 35A). Females of N. forsteri can be separated from other small Nano- meta species by having ovate and deep genital openings, approximately half of the epigynum width, located on the posterior half of the epyginal plate and separated by a triangular septum, approximately half the size of these openings (figs. 35D, 36B).

DESCRIPTION: Female total length 3.3. Cephalothorax length 1.1, width 1.0. Clypeus height 1.0 AME diameter. Cephalothorax background pale yellow, light-gray coloration concentrated over the ocular area and the carapace lateral edges (fig. 36A). Endites and sternum color dark brown (fig. 36C). Cheliceral promargin and retromargin with three and two teeth respectively, cheliceral denticles present ca. 2. Abdomen dorsum background light gray, silvery guanine patches covering all abdomen dorsal surface, except the central line (fig. 36A), lateral surface covered with guanine patches over its dorsal half, ventral half with brown pattern (fig. 36E), ventral surface with a central brown rectangle, flanked by a line of silvery guanine patches (fig. 36C). Booklung stridulatory organ absent. Femur I length 1.8. FD

FIGURE 35. Nanometa forsteri . (GH1139). A. Pedipalp, ventral. B. Pedipalp, ectal. C. Pedipalp, dorsal. D. Epigynum, ventral. E. Epigynum, dorsal. Scale bars: A–D, 0.2 mm; E, 0.1 mm.

Trachea, spinnerets not observed with SEM. Internal genital structures not observed. Epigynum typical of the genus (figs. 35D, E, 36B). Description based on specimen (GH1139).

Male same as female except as noted. Total length 2.4. Cephalothorax length 1.72 width 1.0. Clypeus 0.6 AME diameter. Cephalothorax and abdomen coloration lighter than in female, silvery guanine patches less conspicuous. Cheliceral promargin and retromargin with three and two teeth respectively, cheliceral denticles present ca. 2. Stridulatory organ formed by a cuticular ridge highly sclerotized on the booklung anterior edge, coxa IV retrolateral not examined with SEM. Femur I length 1.8. CEBP tip with a small tooth (figs. 34D, 35A–C). CEMP square in shape and ca. 1/4 of the cymbium length (figs. 34B, 35C). Conductor distal apophyses surface smooth, tip C-shaped (figs. 34, 35A–C). Description based on specimen (GH1139).

VARIATION: Females (N = 2) total length 3.2– 3.3, cephalothorax length 1.1–1.2, width 0.9–1.0.

ETYMOLOGY: The specific epithet is a patronym honoring Raymond R. Forster (1922–2000) and his contributions to arachnology. Among his innumerable discoveries, he is credited with being the first arachnologist to identify nanometines as a natural group.

DISTRIBUTION: This species is found only on the New Zealand South Island (fig. 37E).

NATURAL HISTORY: Nanometa forsteri builds small horizontal orb webs on the lower vegetation.

MATERIAL EXAMINED: N = 9. NEW ZEA- LAND, South Island, Arthur’s Pass National Park, Bridal Veil Track , 42° 55′ 49.6″ S, 171° 33′ 43.4″ E, 819 m, G. Hormiga, N. Scharff, & J. Pedersen, 4–5 February 2012, 3 males, 5 females, MCZ (1 female, DNA voucher GH1139) ; Waimakariri Velley Road , forest close to campground, 43° 0′ 28.8″ S, 171° 34′ 22.7″ E, 655 m, G. Hormiga, N. Scharff, & J. Pedersen, 4 February 2012, sifted litter, 1 female, GWU ; Waitaha Rd., between Greymouth and Franz Josef Glacier, nr. Kakapotahi , 42° 58′ 49.253″ S, 170° 42′ 10.71″ E, 50 m, G. Hormiga, G. Giribet, M. Arnedo, R. Fernández, F. Álvarez-Padilla, R.J. Kallal, & C. Baker, 17 January 2016, GWU ; Woodside Glen Track, nr. Outram , 45° 51′ 14.274″ S, 170° 10′ 18.875″ E, 88 m, G. Hormiga, G. Giribet, M. Arnedo, R. Fernández, F. Álvarez-Padilla, R.J. Kallal, & C. Baker, 22 January 2016, 1 female GWU .

Figures

FIGURE 34. Nanometa forsteri (GH1139), pedipalps. A, Ventral. B, Dorsal. C, Mesal. D, Ectal. Scale bars: 0.2 mm.

FIGURE 36. Nanometa forsteri (GH1139; A–C, E, G, H), N. dutrorum (GH0128; D), and N. dimitrovi (QM S27687; F, I, J). A. Female, dorsal habitus. B. Epigynum, ventral. C. Female, ventral habitus. D. Epigynum, ventral. E. Female, lateral habitus. F. Epigynum, ventral. G. Female, frontal. H. Male, frontal. I. Female, frontal. J. Male, frontal. Scale bars: A, C, E, 1.0 mm; B, D, F–J, 0.2 mm.

FIGURE 37. Distribution of Nanometa in Australia, New Zealand, New Caledonia, and Papua New Guinea. A. Map of region with areas of importance indicated. B. Western Australia. C. Eastern Australia, Papua New Guinea, and New Caledonia. D. Southeastern Australia and Tasmania. E. New Zealand.