Mesabolivar yucuma, Huber, 2018

Huber, Bernhard A., 2018, The South American spider genera Mesabolivar and Carapoia (Araneae, Pholcidae): new species and a framework for redrawing generic limits, Zootaxa 4395 (1), pp. 1-178 : 95-96

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 ).

Figures

FIGURES378–389. Live specimens,Mesabolivar iguazugroup.378–379.M.chapeco sp. n., male and female from Chapecó. 380–381. M. yucuma sp. n., male and female from Turvo. 382–383. M. iguazu Huber, 2000, males from Iguaçú. 384–385. M. charruaMachado etal., 2013, male andfemale from Serra Geral. 386–387.M.catarinensis sp. n., male and female from Serra Geral.388–389. M. bicuspis sp. n., male and female from St. Hilaire/Lange.

FIGURES 397–407. Mesabolivar chapeco sp. n. (397–399, ZFMK Ar 19175) and M. yucuma sp. n. (400–407, ZFMK Ar 19176). 397–402. Left procursi, prolateral, dorsal, and retrolateral views (arrows point at transversal ridges). 403–404. Male chelicerae, frontal and lateral views.405–406. Epigynum, ventral and lateral views.407. Cleared female genitalia, dorsal view. Scale lines:0.2 (397–402; all procursi at same scale); 0.5 (403–407).

FIGURES 433–446. Female epigyna in ventral and lateral views and cleared female genitalia in dorsal views, Mesabolivar iguazu group. 433.M. chapeco sp. n. (ZFMK Ar 19175). 434–436. M.yucuma sp. n. (ZFMK Ar 19176). 437–438. M.iguazu Huber, 2000 (ZFMK Ar 19181). 439–440. M. charrua Machado et al., 2013 (ZFMK Ar 19184). 441–442. M. argentinensis (Mello-Leitão, 1938) (MACN Ar 20050). 443–445. M. catarinensis sp. n. (ZFMK Ar 19189). 446. M. bicuspis sp. n. (ZFMK Ar 19194).

FIGURES 390–396. Mesabolivar chapeco sp. n. (ZFMK Ar 19175). 390–391. Left male palp, prolateral and retrolateral views.392–393.Male chelicerae, frontal and lateral views.394–395.Epigynum, ventral and lateral views.396.Cleared female genitalia, dorsal view.Scale lines:0.5.

FIGURES 736–737. Known distribution of the Mesabolivar iguazu group. TL, type locality. “?”: dubious northern records of M. uruguayensis in Machado et al. (2013) (cf. Huber 2015:60).