Mesabolivar yucuma Huber 2018, sp. n.
Creators: name: Huber, Bernhard A.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Pholcidae
Mesabolivar
Mesabolivar yucuma

description: Mesabolivar yucuma sp. n.
Figs 380–381, 400–407, 434–436
Diagnosis. Distinguished from similar congeners (M. uruguayensis, M. iguazu, M. chapeco) by short proximal processes on male chelicerae (Figs 403–404; similar in M. bicuspis); also by male procursus (Figs 400–402; with distinctive distal sclerotized and membranous elements, dorsal transversal ridge as in M. chapeco), and by shape of epigynum (Figs 405–406, 434–435; anterior plate slightly curved in lateral view, with pair of low processes and pocket on dark sclerotized process at posterior margin).
Etymology. The specific name is derived from the type locality; noun in apposition.
Type material. BRAZIL: Rio Grande do Sul: ♂ holotype, 1♀ paratype, UFMG (21522–23), 12♂ 13♀ paratypes, ZFMK (Ar 19176), Turvo National Park, near Salto do Yucumã (27.136°S, 53.882°W), 175 m a.s.l., 28.x.2014 (B.A. Huber, L.S. Carvalho).
Other material examined. BRAZIL: Rio Grande do Sul: 1♂ 4♀ in pure ethanol, ZFMK (Br 14-194), same data as types. 6♂ 2♀, ZFMK (Ar 19177–78), Turvo National Park, forest near Pousadas das Fontes (27.256°S, 53.877°W), 470 m a.s.l., 27.x.2014 (B.A. Huber, L.S. Carvalho). 2♂ 1♀, ZFMK (Ar 19179), Turvo National Park, Lagoas Trail near headquarters (27.231°S, 53.849°W), 400 m a.s.l., 29.x.2014 (B.A. Huber, L.S. Carvalho); 1♀ in pure ethanol, ZFMK (Br 14-200), same data. 1♂ 2♀, ZFMK (Ar 19180), Turvo National Park, near western entrance (27.244°S, 53.963°W), 400 m a.s.l., 29.x.2014 (B.A. Huber, L.S. Carvalho).
Description. Male (holotype)
MEASUREMENTS. Total body length 3.7, carapace width 1.45. Distance PME-PME 120 µm, diameter PME 120 µm, distance PME-ALE 120 µm, distance AME-AME 20 µm, diameter AME 50 µm. Sternum width/length: 0.95/ 0.55. Leg 1: 39.6 (10.3 + 0.5 + 9.9 + 16.7 + 2.2), tibia 2: 6.4, tibia 3: 4.9, tibia 4: 6.5; tibia 1 L/d: 71. Femora 1–4 width (at half length): 0.22, 0.25, 0.24, 0.21.
COLOR (in ethanol). Carapace pale ochre-yellow with large dark median mark including ocular area and brown lateral margins; clypeus not darker; sternum orange to light brown; legs dark brown, tips of femora and tibiae lighter, darker rings on femora (subdistally) and tibiae (proximally and subdistally); abdomen greenish gray, with darker internal marks dorsally and laterally, ventrally with orange to light brown area in front of gonopore and very indistinct plate in front of spinnerets.
BODY. Habitus as in Fig. 380; ocular area raised; carapace with distinct median furrow; clypeus unmodified; sternum unmodified.
CHELICERAE. With pair of small apophyses distally close to median line and pair of low processes proximally (Figs 403–404).
PALPS. In general very similar to M. chapeco (cf. Figs 390–391), coxa with same distinctive retrolateral apophysis; tarsus without retrolateral hump (in contrast to M. argentinensis); procursus weakly curved, with distinctive sclerotized and membranous distal elements (Figs 400–402), with transversal ridge as in M. chapeco.
LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium on tibia 1 at 2.5%; prolateral trichobothrium present on tibia 1; tarsus 1 with ~30 pseudosegments, distally fairly distinct.
Male (variation). Tibia 1 in 18 other males: 8.3–11.5 (mean 10.0). Some males with legs light brown, sternum ochre-yellow.
Female. In general similar to male. Tibia 1 in 16 females: 6.6–8.8 (mean 7.3). Epigynum as in Figs 405–406, 434–435; anterior plate with pair of low processes and pocket on protruding posterior margin; posterior plate large but indistinct. Internal genitalia as in Figs 407, 436, with pair of large pore-plates in lateral position.
Natural history. The webs were found among tree roots near the ground, under logs, and in other sheltered spaces. Parts of the webs often were exposed to direct sunlight. When disturbed, the spiders vibrated strongly and ran back into the protective shelter.
Distribution. Known from Turvo National Park in Rio Grande do Sul state (Brazil) only (Fig. 737).
description: Published as part of Huber, Bernhard A., 2018, The South American spider genera Mesabolivar and Carapoia (Araneae, Pholcidae): new species and a framework for redrawing generic limits, pp. 1-178 in Zootaxa 4395 (1) on pages 95-96, DOI: 10.11646/zootaxa.4395.1.1, http://zenodo.org/record/1202519